• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.4
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• pp.355-360
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• 2012

Cold drawn(CD) bars feature superb surface roughness, dimensional precision, and straightness. They are used in the manufacture of automotive parts and home electrical appliances. Two cross-roll straighteners have been used to manufacture CD bars for these industries. This study investigated the variation of the gap size between the two cross-rolls. It was found that changes in the gap size have a large influence on the residual stress and plastic deformation. Finite element method(FEM) simulations were performed to study the influence of the gap size on the residual stress in CD bars, and experiments were performed to verify the FEM results. The residual stresses were measured with X-ray diffraction in both the axial and the hoop directions.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.4
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• pp.2401-2406
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• 2015

Pipelines are used by large heavy industries to deliver various types of fluids. Since this is important to maintain the performance of large systems, it is necessary to accurately predict remaining life of the corroded pipeline. However, predicting the remaining life is difficult due to uncertainties in the associated variables, such as geometries, material properties, corrosion rate, etc. In this paper, a statistical method for predicting corrosion remaining life is proposed using Bayesian inference. To accomplish this, pipeline failure probability was calculated using prior information about pipeline failure pressure according to elapsed time, and the given experimental data based on Bayes' rule. The corrosion remaining life was calculated as the elapsed time with 10 % failure probability. Using 10 and 50 samples generated from random variables affecting the corrosion of the pipe, the pipeline failure probability was estimated, after which the estimated remaining useful life was compared with the assumed true remaining useful life.

• Journal of Fashion Business
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• v.22 no.2
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• pp.1-13
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• 2018

3D printing technology, which is expected to play a leading role within the Fourth Industrial Revolution, is becoming distinguished not only in the space, automotive, medical and engineering industries, but also in the area of design. The fashion and textile structures created by 3D printing technology were classified into three types - basic structure, unified structure, and a new physical structure. When traditional weaving, knitting, and stitching was reinterpreted through 3D printing, there were apparent limitations in reproducing the characteristics of fabric structures due to differences in the materials and structures of traditional textiles. New physical structures are being developed to break away from merely reproducing traditional textile structures, and to bring out the characteristics of 3D printing technology. As examples of new physical structures, there are the kinematics structure which utilizes the hinge method, mesostructure cellular material, and the N12 disk structure. Such techniques potentially open a new paradigm of fashion and textile structures. Some innovative aspects of 3D printing technology may result in changes in the methods of collaboration, manufacturing, and distribution. Designers are receiving help from specialists of various backgrounds to merge 3D printing technology to create original works. Also, 3D printing not only makes personalized custom designs available, but shortens the distribution channels, foretelling a change within the fashion and textile industry.

• Polymer(Korea)
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• v.37 no.2
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• pp.184-195
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• 2013

Acrylic pressure sensitive adhesive (PSA) tapes were used for the automotive, the electrical and the electronic industries and the display module junction. In this study, the manufacture of high-strength structural tape used 2-ethylhexyl acrylate (2-EHA) and acrylic acid (AAC), and UV irradiation for photo-polymerization, and the semi-structural properties of acrylic PSA tape with the AAC content and inorganic filler $SiO_2$ content were investigated. The initial adhesion strength was lowered by the rigidity of molecule chains due to the use of AAC, and the adhesion strength increased with increasing wetting time. The wetability, contact angle, and SEM images of PSA tapes with various contents of AAC were determined. Without filler, the peel strength and dynamic shear strength of PSA tape showed inverse correlation but the peel strength and dynamic shear strength increased with increasing filler content. From these correlations the PSA tapes could be optimized for the applications requiring high performance.

• Korean Chemical Engineering Research
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• v.46 no.5
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• pp.945-948
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• 2008

Nanocomposite materials provides efficient reinforcement, thermal endurance, and many other advantages depending on the additives used, with applications in the aerospace, automotive, and biomedical industries. Here, epoxy based nanocomposites were synthesized in the presence of Cloisite 15A and characterized with TEM, XRD, TGA, and DMA. To determine the effect of the clay d-spacing, Cloisite 20A was also used to synthesize the nanocompostes. In addition to the traditional hot plate method, an ultrasonicator was used to investigate the effect of different types of mixing on the properties of the nanocomposite; no significant effect was found. An examination of the nanocomposite morphology revealed that all the nanocomposites synthesized yielded an intercalated structure. When 5 wt% of Cloisite 15A was used with 20 min sonication time, the storage modulus increased 10% over the neat(no clay) nanocomposite. In general, the presence of Cloisite 15A produced a better storage modulus than Cloisite 20A.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.433-439
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• 2017

This research investigates the manufacturing process and characteristics analysis of $BKNO_3$ (Boron Potassium Nitrate) as pyrotechnic are commonly found in the aerospace, defense, and automotive industries. A solid pyrotechnic mixture is composed of an oxidizing agent, fuel, and binder. Precipitation process was used to uniformly mix the raw material. Through the analysis of the material characteristics and thermal response is designed optimum ratio by NASA CEA program. It was compared by performing the evaluation of these size/shape/sensitivity/calorimetry characteristics.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.2
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• pp.155-158
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• 2017

With the help of technical development in the electronic industries, the electronic devices employing the cutting-edged technology are spread in all the area requiring electromagnetic communications. Especially, because of the presence of electronic devices in a variety of research fields like automotive vehicle, train, and aircraft, the research area such as the malfunction and critical damage of the internal system and microwave devices due to the unexpected radiated high-powered EM effects are very important even for the possible occurrence of human damage. In this paper, the effects of electromagnetic fields into the cable connecting the electronic devices and many sensors inside the target structure is treated because of potential malfunction or hardware disorders. In addition, correlation function and transmission line theory have been employed for the analysis of the induced current on the cable inside an electrically large resonant structure.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2005.10a
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• pp.283-288
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• 2005

Application of semiconductor sensors has widely spreaded into various industries because those have several merits like easy miniaturization and batch production comparison with previous mechanical sensors. But external conditions such as thermal and repetitive load have a bad effect on sensors's lifetime. Especially, this paper was focused on fatigue life of a interconnect made by various materials. Firstly we implemented the stress analysis for interconnect under thermal load and wording pressure. And the fatigue lifetime of each material was induced by Manson & Coffin Equation using the plastic stress-strain curve obtained by the plastic-elastic Finite Element Analysis.

• Journal of Information Processing Systems
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• v.10 no.1
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• pp.103-118
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• 2014

Over the last couple of years, traditional VANET (Vehicular Ad Hoc NETwork) evolved into VANET-based clouds. From the VANET standpoint, applications became richer by virtue of the boom in automotive telematics and infotainment technologies. Nevertheless, the research community and industries are concerned about the under-utilization of rich computation, communication, and storage resources in middle and high-end vehicles. This phenomenon became the driving force for the birth of VANET-based clouds. In this paper, we envision a novel application layer of VANET-based clouds based on the cooperation of the moving cars on the road, called CaaS (Cooperation as a Service). CaaS is divided into TIaaS (Traffic Information as a Service), WaaS (Warning as a Service), and IfaaS (Infotainment as a Service). Note, however, that this work focuses only on TIaaS and WaaS. TIaaS provides vehicular nodes, more precisely subscribers, with the fine-grained traffic information constructed by CDM (Cloud Decision Module) as a result of the cooperation of the vehicles on the roads in the form of mobility vectors. On the other hand, WaaS provides subscribers with potential warning messages in case of hazard situations on the road. Communication between the cloud infrastructure and the vehicles is done through GTs (Gateway Terminals), whereas GTs are physically realized through RSUs (Road-Side Units) and vehicles with 4G Internet access. These GTs forward the coarse-grained cooperation from vehicles to cloud and fine-grained traffic information and warnings from cloud to vehicles (subscribers) in a secure, privacy-aware fashion. In our proposed scheme, privacy is conditionally preserved wherein the location and the identity of the cooperators are preserved by leveraging the modified location-based encryption and, in case of any dispute, the node is subject to revocation. To the best of our knowledge, our proposed scheme is the first effort to offshore the extended traffic view construction function and warning messages dissemination function to the cloud.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.12
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• pp.5412-5419
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• 2011

The need is growing for high-speed spindle because various equipment are becoming more precise, miniaturization and high speed with the development of industries. Air-lubricated dynamic bearings are widely used in the optical lithographic manufacturing of wafers to realize nearly zero friction for the motion of the stage. Air-lubricated dynamic bearing can be used in high-speed, high-precision spindle system and hard disk drive(HDD) because of its advantages such as low frictional loss, low heat generation, averaging effect leading better running accuracy. In the paper, numerical analysis is undertaken to calculate the performance of air-lubricated dynamic bearing with herringbone groove. The static performances of herringbone groove bearings which can be used to support the thrust load are calculated. Electrochemical micro machining($EC{\mu}M$) which is non-contact ultra precision machining method has been developed to fabricate the air-lubricated dynamic bearing and optimum parameters which are inter electrode gap size, concentration of electrolyte, machining time are simulated using numerical analysis program.