Dong Won Jung

Jeju National University | jejunu · Faculty of Mechanical and System Engineering

Fractals in nature follows the Fibonacci series and shows angular rotation mostly in anticlockwise direction. The recent study suggests that fluids especially water stores its molecules in a series. The chirality of water molecules can allow vortex generation only in counter clockwise direction. If both these properties are combined, any viscoelast...

Single point incremental forming process, which is also known as SPIF, that forms from one direction. SPIF process was used for milling an aluminum metallic sheet. In this paper, an aluminum (A5052) sheet was formed in a conical shape by the SPIF process. The A5052 sheet was deformed by the computer numerical control (CNC) technology in the T60 ser...

Forming a metallic sheet along with the consideration of computer simulation and experiment had benefited the milling industry for a long time. The ideal forming, without an error, is a concerning topic. So, the computer simulation had the advantage then direct forming. To observe the results before doing the real experiments simulation comes handy...

The single point incremental forming (SPIF) process is a high-trend method for forming a metal in a desirable shape. Forming parameters is an important part of deforming metal sheets. So, while reshaping a metal sheet parameters like tools, toolpath, material properties, sheet thickness, and lubricant were considered. Since the Aluminum sheet is us...

Tensile tests on AA5005 alloy were conducted on model MTS-810 tensile test machine during temperature 633-773 K and strain rate 0.0003-0.03 s ⁻¹ . The flow stress–true strain curves were obtained. In order to analyze the flow stress behavior of aluminum AA5005 alloy, the phenomenological Fields-Backofen equation based on the fitting regression anal...

As an intelligent global optimization method, the genetic algorithm has tremendous potential for improving flow behavior modeling and analysis. Based on flow stress-true strain curves of Al-Mg AA5005 alloy under temperature 563∼773 K and strain rate 0.0003∼0.03s−1, a phenomenological model named Arrhenius-type (A-T) was established to describe the...

A reverse-offset printed temperature sensor based on interdigitated electrodes (IDTs) has been investigated in this study. Silver nanoparticles (AgNPs) were printed on a glass slide in an IDT pattern by reverse-offset printer. The sensing layer consisted of a sucrose film obtained by spin coating the sucrose solution on the IDTs. The temperature se...

Recently, developing flexible and economical sheet forming processes and technologies is very important. Incremental forming is one of the promising sheet forming processes and it can be valid for these purposes. Especially, single-point incremental forming (SPIF) becomes popular because of its low expenses and rapidly adaption to customers’ needs....

Due to the continuous emergence of new alloys and the improvement of basic research requirements for aluminum alloy, researchers need to further study the flow constitutive relationship of new aluminum alloys. This paper used Model MTS-810 tensile machine to conduct tensile tests on AA5005 aluminum alloy at temperature of 360°C and strain rate of ....

On the worldwide tendency of wight reduction of automobile, aluminum is drawing a large number of researcher’s sights because it’s advantages of low weight, corrosion resistance, flexible and so on. Aimed at understanding high-temperature flow behavior of aluminum alloy A5005, tensile tests were conducted at temperatures 360°C, 430°C, 500°C and str...

A high performance flexible temperature sensor for environmental and health monitoring has been fabricated using various combinations of composite blend of poly vinylidene fluoride / poly (3,4-ethylenedioxythiophene)-poly (styrenesulfonate) (PVDF/PEDOT:PSS). The response curves and working principle were investigated and sensors were then fabricate...

In the multi-stage incremental forming of straight-wall parts based on the extrusion from the forward and reverse side of the sheet, different forming area zoning will have different effects on the part thickness. The larger the area of the sheet metal participating in forming is, the better the thickness distribution is. However, the forming area...

In order to realize the CNC incremental forming of the straight wall parts, a CNC incremental forming method with the sheet metal posture adjustment in multiple directions based on the model partition and the non-steep surface was proposed in this paper. With the help of the non-steep surface, the sheet metal posture is adjusted to reduce the formi...

To realize the purpose of energy saving, materials with high weight are replaced by low-weight materials with eligible mechanical properties in all kinds of fields. Therefore, conducting research works on lightweight materials under specified work conditions is extremely important and profound. To understand the relationship of aluminum alloy AA500...

In this paper the issues of modeling the process of forming sheet materials using method of incremental forming for the manufacture of thin-walled non-axisymmetric parts. The proposed method of forming implemented by deformation of sheet material by providing the required trajectory of movement of the working tool in order to obtain the surface of...

Single point incremental forming (SPIF) process is used to deform complex shapes. Through SPIF process metallic sheet is formed. The formability of a AA5052 is evaluated using SPIF method for industry level product. The utility of SPIF is broad in industries because of the simple operating system of manufacturing and designing metal substances thro...

The liquid flow inside the Hele-Shaw cell can be used to explain the shape of snowflake, rupture nucleation shape in bubble, shape of leaf, shape of cells in Plants and Animals, etc. When the pressure is applied on the thin layer of liquid, the liquid flow happens only in the edges. In addition to this, the liquid flow inside the Hele-Shaw will sto...

In the current report, characteristics of the propagated wave in a sandwich structure with a soft core and multi-hybrid nanocomposite (MHC) face sheets are investigated. The higher-order shear deformable theory (HSDT) is applied to formulate the stresses and strains. Rule of the mixture and modified Halpin–Tsai model are engaged to provide the effe...

Wave propagation simulation in a multi-hybrid nanocomposite (MHC)-reinforced doubly curved open shell covered with piezoelectric actuator is examined for the first time. The third-order shear deformation theory (third-order SDT) is applied to formulate the stress–strain relations. Rule of the mixture and modified Halpin–Tsai model are engaged to pr...

Remanufacture the used product saves money along with maintaining waste material. Trash material are concern and need to reuse. So remanufacturing technologies is important. Big companies are interested in producing product from reusable materials. Remanufactured products are increasing because it has a benefit for environment as an eco-friendly an...

Forming a sheet in a normal room temperature is a famous method of reshaping a metal. To avoid the fracture, proper selection of a metal, sheet thickness and purity of metal are considered. So, research considering the parameters along with spring back are discussed throughout the paper. A 0.5mm thickness sheet is being formed by using Single point...

In order to study the influence of the pitch of the spiral toolpath on the forming quality in the single-point incremental forming, three kinds of spiral toolpath with pitch of 0.2 mm, 0.5 mm and 1 mm were generated by using the UG software, and the thickness distribution, contour dimensional accuracy and equivalent stress of the formed parts based...

This paper examines the forming of sheet materials by incremental forming. Proposed and researched methods of deformation and the tool path based on which choice is the most appropriate circuits and paths for receiving the hemispherical parts. Abaqus software package is used to develop a method to model incremental forming. All simulation results a...

The Single point incremental sheet forming process known as a SPIF process. Which got a great attraction among other existed sheet metal forming processes because of their flexibility to manufacture complex products. The aluminum alloy material mechanical properties are adopted and integrated into the finite element (FE) code. The tool paths for th...

View Video Presentation: https://doi.org/10.2514/6.2022-0783.vid Study of the laminar jets is vital because of its usage in propulsion unit. The carburetors need the jets to be streamlined for the better mixing of fuel with the air. There is a limited study on the behavior of laminar jets in contact, especially multiple jets. In this paper, we para...

The single-point incremental forming process has witnessed significant advantages in automobiles, aerospace, and medical applications in recent years because of its flexibility in manufacturing complex shapes. In detail, the components are produced only using the toolpath, which is guided by computer-aided manufacturing software. However, during th...

The object of research is geometric models of the process of incremental forming of parts from sheet material. The subject of research is a graphical model for finding the optimal values of the parameters of the forming process based on multidimensional descriptive geometry. The author of the article discusses the main optimizing factors and proces...

The existing double sided incremental forming (DSIF) mostly uses two tools with the same diameter as the upper/lower tools, which is not conducive to improve the forming quality and forming efficiency. In this paper, the influence of the different combination of the upper and lower tool head diameters on the thickness distribution and the contour d...

View Video Presentation: https://doi.org/10.2514/6.2021-3553.vid Study of the laminar jets is vital because of its usage in propulsion unit. The carburetors need the jets to be streamlined for the better mixing of fuel with the air. There is a limited study on the behavior of laminar jets in contact, especially multiple jets. In this paper, we para...

Single point incremental forming (SPIF) is a die-less forming method in which the sheet is incrementally formed using the forming tool with predefined contour paths of the desired shape. Moreover, any complex parts can be manufactured using this method by modifying the tool paths and the forming tool dimensions because of its flexibility. This pape...

Single point incremental forming (SPIF) is a choice of interest in many manufacturing industries due to its wide range of applications. Materials such as copper, aluminum, steel, and many others formed various complex shapes through this process. However, the forming process could sometimes result in process defects, which could strongly influence...

The engineering field's main issues are often identified to be estimating the deformation and the strain measurements of the working material. Gauging displacements until the fracture more accurately is crucial in experimental procedures for assessing the chosen material properties. This research paper investigates the commercial magnesium alloy (A...

Nanocomposites are the upgraded form in which the reinforcement, matrix, and filler all play a key role in the provision of properties and their enhancement. Computationally, the controlled procedures are described as follows: conceptual design of a test specimen, finite element model of a test specimen, description of structural analysis used, bou...

The single-point incremental forming process (SPIF) is one of the emerging manufacturing methods because of its flexibility in producing the desired complex shapes with higher formability at low-cost compared to traditional sheet forming methods. In this research work, we experimentally investigate the forming process to determine the influence of...

The cold roll forming process is broadly used to produce a specific shape of cold-roll formed products for their applications in automobiles, aerospace, shipbuilding, and construction sectors. Moreover, a proper selection of strip thickness and forming speed to avoid fracture is most important for manufacturing a quality product. This research aims...

Flying fish has the capability of gliding in the air for more than 200 m. The biological design of the Flying fish is quite impressive which allows the fish to swim and fly efficiently. An attempt is made to use this bioinspired design of this fish to conceptually design an Unmanned Amphibious Vehicle (UAV). Keeping the payload for surveillance as...

In this article, amplitude, and vibrational characteristics of a rotating orthotropic piezoelectric nanodisk are presented. The centrifugal and Coriolis effects due to the rotation are considered. The strains and stresses can be determined via the higher-order shear deformable theory (HSDT). For accessing to size effects, the nonlocal strain gradie...

In this paper, wave propagation analysis of multi-hybrid nanocomposite (MHC) reinforced doubly curved panel embedded in the viscoelastic foundation is carried out. Higher-order shear deformable theory (HSDT) is utilized to express the displacement kinematics. The rule of mixture and modified Halpin–Tsai model are engaged to provide the effective ma...

Bird strike analysis is of great importance because of the loss it can create. Since there are many factors which influences the level of damage, the computational cost for determining the strong factor is high. Usage of the optimization techniques will give the significant reduction of computational cost. Taguchi method is used to find out the str...

Most of the cells in living things is in polygonal shape. The reason behind it is the molecular structure of the water. Snowflake under similar environment has different shape because of the density of water and its chemical property. The similar arrangement is found in cells of living things. Thus, our study is all about the molecular structure of...

The author wishes to make the following corrections to this paper [...]

In this article, amplitude, and vibrational characteristics of a rotating laminated cantilever microdisk are presented. The centrifugal and Coriolis effects due to the rotation are considered. The strain and stress relations can be determined via the higher-order shear deformable theory (HSDT). For accessing to size-effects, the nonlocal strain gra...

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Honeycomb structures have the geometry of the lattice network to allow the minimization of the amount of used material to reach minimal material cost and minimal weight. In this regard, this article deals with the frequency analysis of imperfect honeycomb core sandwich disk with multiscale hybrid nanocomposite (MHC) face sheets rested on an elastic...

In this study, the vibrational characteristics of a rotating multi-hybrid nanocomposite reinforced (MHCR) cantilevered disk (MHCRCD) are presented. The centrifugal and Coriolis effects due to the rotation are considered. The strains and stresses can be determined via the high-order shear deformable theory (HSDT). For access to various mass densitie...

This article presents the axial buckling analysis of polymer-CNT-fiber nanocomposite annular system (PCFCAS) resting on Winkler-Pasternak substrates under various temperature gradients. With the aid of Hamilton’s principle and the higher-order shear deformation theory (HSDT), the governing equations are derived. For developing an accurate solution...

Mechanical systems especially annular disks have many applications in different fields such as engineering, agriculture, and medicine. In this regard, the large amplitude vibrations of multi-scale hybrid nanocomposite annular system (MHCAS) under hygrothermal environment and subjected to mechanical loading. Also, the structure is covered with elast...

Shape of cell in Plants and Animals

The frequency characteristics of circular/annular plates reinforced with multi-scale hybrid laminates nanocomposite (MHLN) are presented via the state-space formulation based on three-dimensional (3D)-elasticity theory. The circular/annular plate is under initial lateral stress and composed of multilayers with carbon nanotubes (CNTs) uniformly disp...

This article deals with the vibrational characteristics of a laminated composite annular microplate using a non-classical continuum theory called modified couple stress theory (MCST). The structure is covered with a viscoelastic foundation that is simulated via the Kelvin-Voight model. The non-classical governing equations and boundary conditions o...

Theory of shape is explained in the work based on thin flow inside the thin geometry.

In this article, a mathematical derivation is made to develop a nonlinear dynamic model for the nonlinear frequency, and chaotic responses of the graphene nanoplatelet (GPL) reinforced composite (GPLRC) doubly-curved panel subject to an external harmonic load. Using Hamilton's principle and the Von-Karman nonlinear theory, the nonlinear governing e...

Interest in studying of the shell arises from the fifties of twentieth century. Assemblies which contains thin shells, find wide use in the modern engineering especially in ships, aircraft and spacecraft industry. In today’s aerospace and aircraft industries, structural efficiency is the main concern. In this paper the shell vibrations and buckling...

In the field of engineering, automobile and aerospace components are manufactured based on the desired applications from the metal forming process. For producing better quality of both symmetry and asymmetry mechanical parts, understanding the material deformation and analytical representation of the material ductility behavior for the working mate...

In the present study, based on 12-unknown higher order shear deformation theory (HSDT), buckling and vibration analysis of FG-CNTRC rectangular plate are investigated for various types of temperature distribution and boundary conditions. Implementing Hamilton’s principle, the equations of motion are derived and solved by adopting the Navier solutio...

Due to the remarkable progress in the field of the manufacturing process, smart composites have become the desired target for high-tech engineering applications. Accordingly, for the first time, thermal buckling, critical voltage and vibration response of a thermally affected graphene nanoplatelet reinforced composite (GPLRC) microdisk in the therm...

Over the last few years, some novel researches in the field of medical science made a tendency to have a therapy without any complications or side-effects of the disease with the aid of prognosis about the behaviors of the substructure living biological cell. Regarding this issue, nonlinear frequency characteristics of substructure living biologica...

In this article, size-dependent vibrations and stability of moving viscoelastic axially functionally graded (AFG) nanobeams are investigated numerically and analytically, aiming at stability enhancement of translating nanosystems. Also, a parametric investigation is presented to elucidate the influence of various key factors such as axial gradation...

In this article, vibration of viscoelastic axially functionally graded (AFG) moving Rayleigh and Euler-Bernoulli (EB) beams are investigated and compared, aiming at performance improvement of translating systems. Also, a detailed study is performed to elucidate the influence of various factors such as rotary inertia factor and axial gradation of ma...

This study presents the frequency analysis of a size-dependent laminated polymer composite microtube using a nonlocal strain-stress gradient (NSG) model. By applying energy methods (known as Hamilton’s principle), the motion equations of the laminated micro tube composites are developed. The thermodynamic equations of the laminated microtube are ba...

This research work is focused on the cold roll forming process to produce U-channel from the flat sheet. The mechanical properties of aluminum alloy was obtained from the tensile test and subsequently, the properties were incorporated into LS-DYNA to define the material plastic region. The forming process involves the progressive sheet deformation...

Even though New materials are coming into the market Aluminum Alloy is still widely used in Aerospace, Automobile and defense industries. The main reason is these alloys are light weight, high strength and easy to recycle. Many traditional methods like punching, shearing and blanking has been widely used previously to deform these sheets in differe...

Isothermal tensile test of medium carbon steel material was conducted on a computer controlled servo-hydraulic testing machine at the deformation temperatures (923 to 1223 K) and the strain rates (0.05 to 1.0 s ⁻¹ ). Using the experimental data, the artificial neural network (ANN) model with a back-propagation (BP) algorithm was proposed to predict...

The isothermal tensile test of medium carbon steel material was conducted at deformation temperatures varying from 650 to 950 ∘ ∘ C with an interval of 100 ∘ ∘ C and strain rates ranging from 0.05 to 1.0 s −1 −1 . In addition, the scanning electron microscopy (SEM) procedures were exploited to study about the surface morphology of medium carb...

Fossil fuel, especially oil, represents the engine of nowadays life. Oil companies work hard in order to extract it from subsurface hydrocarbon reservoirs. The operations at which oil is being extracted from these reservoirs are referred to as drilling operations. Drilling operations are per-formed with the means of drilling rigs. However, due to t...

In materials processing, practical understanding of materials behavior at elevated temperatures and high strain rates is necessary for modeling the real system behavior. The tensile deformation behavior of AISI-1045 steel material is investigated at deformation temperatures (923−1223 K) and strain rates (0.05−1.0 s⁻¹). This paper proposes a detaile...

Consistent and reasonable characterization of the material behavior under the coupled effects of strain, strain rate and temperature on the material flow stress is remarkably crucial in order to design as well as optimize the process parameters in the metal forming industrial practice. The objective of this work was to formulate an appropriate flow...

The study of cavitation is of topical interest in both physical and biological sciences. The surface roughness changes the effect of cavitation on a material surface. Due to cavitation, the material with low surface roughness value has relatively more damage, when compared to the one with higher value. In this paper, preliminary numerical studies a...

To machine materials for dies, complex cavities & intricate jobs, a non-conventional machining process called electrical discharge machining is used. Areas like aeronautics, die & mold manufacturing, Injection molding etc. find a wide range of applications in this process. Improving the MRR, reducing the tool wear rate & surface roughness is the ma...

Washing machine has greatly influenced people’s life styles by providing easy means of washing clothes and drying them out to a considerable extent. This not only saves time and amount of water used but also helps the user to wash and dry clothes with a lot of ease due to its fully automatic nature. But taking advantage of fully automated technolog...

Incremental sheet metal forming, is a non-conventional machining process which offers higher formability, flexibility and low cost of production than the traditional conventional forming process. Punch or tool used in this forming process consecutively forces the sheet to deform locally and ultimately gives the target profile. Various machining par...

Aiming at the problem of the springback in the CNC incremental forming, a method for predicting the springback and generating the compensated forming trajectory was proposed based on the explicit and implicit finite element analysis. First, the middle surface of the simulated sheet metal part was reconstructed after the springback simulation with t...

Injection molding is the most effective process for the mass production of plastic parts. However, there are various plastic part surface defects which occur during the injection molding process. Sink marks are among the most difficult surface defects to improve. The sink marks usually appear as depressions on the surface of a molded part. These de...

In manual transmission systems the shifting of power from input shaft to output shift is the key feature for achieving better efficiency in manual automobiles. During running of automobile under different load condition the possibility of efficiency loss is very high especially in heavy vehicles. The main agent which affects the efficiency of manua...

This study was carried out to evaluate a new roll forming process involving pre-heating using a gas torch. The temperature distribution for the formed sheet was observed using a 3D-IR graph generated from a thermal imaging camera. The appropriate distance between the formed sheet and the butane gas torch was also determined based on the results of...

The bi-layer materials have been used widely during past decades due to their specific characteristics like lighter weight, more corrosion resistance, and insulation features in comparison with mono-layers which consisting them. In this research the aim is achieving to best combination of bi-layer material (Al3105-St14) to satisfy two objectives of...

A brief review of the mechanical characterization of viscoelastic materials under uniaxial, biaxial and multiaxial stress condition is carried out in this paper. Parametric analytical studies have been done in a simulated tubular specimen with different internal pressure loadings at various material properties. We observed that the relaxation modul...

Conservative Coulomb method indicates steady constant of rub in thin metal panel making that appears or feels close to the real thing. It contributes to describing attainable future event too high shear pressure in making ahead in the position of high R-value steel (AHRS). The study is conducted by pretend the making and spring back of a specific p...

Roll forming is a continuous profile production process to form sheet metal progressively into the desired shape with closer tolerances. The process offers several advantages such as complex geometrical shapes, high strength, dimensional accuracy, closer tolerances, better quality and consistency, high production rate, improved conformity, and good...

The roll forming is one of the simplest manufacturing processes for meeting the continued needs of various industries. The roll forming is increasingly used in the automotive industry to form High Strength Steel (HSS) and Advanced High Strength Steel (AHSS) for making structural components. In order to reduce the thinning of the sheet product, trad...

The aim of the project is to manufacture a welding machine which simplifies the work and improve the accuracy. The working principle of this machine is different other that of other welding machine. The aluminum work piece is held in the vice. The two pieces of aluminum work piece is welded with the help high speed drilling head with friction tool....

Ultra Violet (UV) pulse are widely used for micromachining in the research and development of Information Technology (IT), Nano Technology (NT), and Bio Technology (BT) products because due to short wavelength of the laser it not only allows micro drilling, micro cutting and micro grooving with high accuracy, but acts also as high penetrating coeff...

Roll forming process, due to increased product performance, higher quality, and lower cost with other advantages, has been made suitable process to form any shapes in the sheets. In this paper stress, strain and thickness distribution in the steel galvanized hot coil commercial (SGHC) sheet with Round shape ribs formed by roll forming process was i...