• Journal of the Korean Society for Heat Treatment
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• v.20 no.4
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• pp.175-180
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• 2007

The hardness of cold-forged products is in close relationship with its effective strain. This study presented the estimating method of hardness for cold-forged SKH9 products without hardness tests in view of resistance to plastic deformation using finite element code, DEFORM$^{TM}$. The flow stress equation obtained from the compression test was only used as a basic data to estimate the relationship between effective strain and hardness. In addition, this new estimating method was applied to the cold-forged product which was widely used in industrial field to show the feasibility. As a result, the predicted hardness numbers through FE simulation showed good agreement with the measured hardness numbers. It is possible to estimate the hardness not by hardness tests, but by only computer simulations for the deformed products. Also, effective strain values were possibly estimated by measuring hardness numbers, and vice versa.

• Composites Research
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• v.27 no.6
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• pp.231-235
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• 2014

Autoclave processing has a good quality of product, but manufacturing cost is expansive. After curing of composite, the unwanted deformation and distortion increase the manufacturing cost by redesign of tool parts. Therefore, manufacturing cost down is a big issue in processing level. For the reduction of tool costs, it is important to investigate the effects of tool materials and tool surface conditions. In this paper, we organized user subroutine in ABAQUS to consider the thermal effects of part and tool, and the results are compared with commercial code, COMPRO. And this paper suggests reference point for the selection of tool materials to reduce manufacturing costs.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.10a
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• pp.879-886
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• 2007

EPC (Electronic Product Code) tags and RFID (Radio Frequency IDentification) technology are said to have potential to change the ways individuals, organizations and societies operate on the everyday basis. In the near future, it is expected that every major retailer will use RFID and EPC systems to track the movement of products from suppliers to warehouses, store backrooms and eventually to points of sale. Recent efforts in EPC tags and RFID technology attempt to achieve an appropriate kind of interaction between technical and business areas. In this paper, we explore the fundamental characteristics of RFID and EPC applications and then review the different research studies of RFID technology and EPC system that have been proposed new theories and concepts that have emerged and utilized in different business fields of manufacturing and logistics. It provides an overview of the study achievements within the domain and critically evaluates the various approaches through the use of a case study and the construction of its comparison framework. The different research studies indicated that RFID and EPC systems will become more pervasive in the future and the changes that occur over the next few years will make for a further fascinating research area.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.9
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• pp.1309-1316
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• 2003

A premixed-compression-ignition engine has been studied to improve the efficiency and to decrease exhaust emissions. However those systems have some difficulties for controlling combustion process. Radical is an activated chemical species formed by a chemical chain reaction between reactant and product. When the chain reactions occur, the energy bond of species is broken easily by the released radicals. The combustion chamber of the premixed-compression-ingnition engine is consist of a main chamber with lean premixture and a subchamber with rich premixture. Those are connected by narrow cylinderical connections. With ignition start in the subchamber, many different kinds of radical is jetted into the main chamber. The premixed gas in main chamber is quickly burned up by the radical ignition in multi-pionts. In this paper, the combustion phenomena in a constant volume combustor having a radical injector are numerically analyzed. The some constants in the reaction rate equation are adjusted by the experimental results tested in the same geometrical chamber. The code is applied on the two combustors in a wide range of equivalence ratio. The results show that the burning time is much shorter in the combustor having radical injector.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.4B
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• pp.599-609
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• 2010

Korean government has recently abrogated WIPI policy to open domestic mobile phone market to the world, which may result in the influx of foreign smart phones. This circumstance has given users more wide range of choices to buy a product and also has brought benefit to buy mobile phone cheaply. On the other hands, this change might have brought potential danger of mobile malware incidents which have only occurred in foreign countries. There are standardized analysis methods and response guides for computer malwares, not but for mobile malwares in our country. In this paper, we introduce existing mobile malwares and available tools for their analysis. Considering domestic circumstances which might not be properly protected against mobile malwares, we propose analysis methods and response guide of mobile malwares.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1997.06a
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• pp.5-15
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• 1997

It is the objective of this study that by conducting the serni-solid extrusion using A12024, the effect of various process variables on the quality of extruded product and extrusion force is understood. The results of experiment are compared with those of finite element simulation in order to verify the effectiveness of the developed FE-simulation code. In order to simulate densification in the deformation of serni-solid material, the semi-solid material is assumed to be composed of solid region as porous skeleton following compressible visco-plastic model and liquid region following Darcy's equation for the liquid flow saturated in the interstitial space. Then the flow and deformation of the semi-solid alloy are analyzed by coupling the deformation of the porous skeleton and the flow of the eutectic liquid. It is assumed that initial solid fraction is homogeneous. Yield and plastic potential function presented by Kuhn and constitutive model developed by Gunasekera are used for solid skeleton.

• Transactions of Materials Processing
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• v.21 no.8
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• pp.493-498
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• 2012

A wheel nut wrench is one of the hand tools used to loosen and tighten lug nuts on automobile wheels and it has generally a solid-type geometry for commercial vehicles. However, the solid-type wheel nut wrenches manufactured by hot forging processes exhibit several drawbacks such as heavy weight and rough surface finish. Thus, many efforts have been devoted to change the part geometry and improve the manufacturing process. For this purpose, the weight of the final product can be reduced drastically using a hollow tube as the initial stock, which can be manufactured by the more economical manufacturing process of cold forging. In this study, the cold forging of a hollow-type wheel nut wrench for commercial vehicles was designed based on the results of fundamental experiments and CAE analyses using the commercial finite element code DEFORM-3D. In addition, cold forging experiments were conducted on a special-purpose forming machine for hollow wheel nut wrenches in order to validate the designed process sequence. As results, it was found that the final products with a weight reduction of 39% and better surface appearance can be manufactured without any defect with the newly designed cold forging process.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.5 s.182
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• pp.51-58
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• 2006

The necessities for heightening fuel efficiency as well as lightweight design, lead to an increase of the use of aluminum alloys in the automobile industry. Extruded aluminum profile channels are used widely for the design of frame parts as lightweight assemblies, especially if a high stiffness is needed. While many applications can be realized with forming of hollow square-sectioned extruded profiles such as a stretch bending and a hydro-forming, some applications demand the use of a press bending which can be hardly found in the previous study. In this study, by introducing the use of a press bending into car sub-frames, the demands for higher accuracy as well as higher flexible method than the conventional methods will be satisfied. With respect to the design of sub-frames, the process planning was performed from the shape of a sub-frame product. The designed processes were analyzed by the commercial FEM code, DEFORM-3D. Forming dies for the each process were designed and prototypes of sub-frames were manufactured by the verified farming process. In addition, some of the important features of design parameters in the press bending were reviewed.

• Journal of the Institute of Convergence Signal Processing
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• v.1 no.1
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• pp.89-96
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• 2000

In this paper, we propose a vision algorithm for the inspection of very small RF-chip inductor which is used in mobile-communication terminal. The proposed method divides coil part from the inductor body by local adaptive thresholding and integral projection method. After dividing work, the coil components are extracted by thinning and labelling techniques. The test items are the number of turns, the intervals in coil, and the measure of uniformity between the extracted lines. If the values of these are more than the specific value a tested product is decided bad one. In the simulation, the proposed method has a good performance.

• Proceedings of the Korean Information Science Society Conference
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• 2007.10c
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• pp.179-184
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• 2007

EPCglobal 네트워크란 EPC(Electronic Product Code)와 RFID(Radio Frequency Identification) 기술을 바탕으로 제품에 식별번호를 부여하고 정보를 저장할 수 있는 공간을 네트워크로 연동하여 공급자, 수요자, 소비가 제품에 관련된 정보를 알 수 있게 해주는 시스템을 말한다. 또한 EPCglobal 네트워크 아키텍처 프레임워크(EPCglobal network architecture framework)는 EPC를 사용하여 공급과 유통망 강화라는 업체간의 공동 목표를 위한 서비스하는 것이다. EPCglobal 네트워크 아키텍처 중 EPCIS(EPC Information System) 수집 애플리케이션, EPCIS 접근 애플리케이션에서 이벤트 정의 시 공통적인 의사소통을 위한 표준 어휘 정의가 필수적이며, 그 어휘 종류에는 표준 어휘(standard vocabulary)와 사용자어휘(user vocabulary)가 있다. 이 논문은 이 가운데 EPCglobal 네트워크 아키텍처의 표준 어휘 정의에 초점을 두고, 사용자 어휘는 부분적으로 정의하고자 한다. 따라서 이 논문은 EPCglobal 네트워크 프레임 아키텍처의 이벤트 정의 시 사용될 표준 어휘를 제안하고, XML 구현을 통해 실제 사용 가능한 환경을 제공할 것이다.