• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1998년도 춘계학술대회논문집
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• pp.224-230
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• 1998

Non-heat-treated type material has been investigated for formability compared to heat-treated material. It is very important in automation of metal forming, since it has difficulties of controlling heat treating system by the computer and has bottle neck problem related with heat treatment. In this paper, we have concerned about mechanical properties of non-heat-treated material after the forging. To compare the characteristics between heat-treated material and non-heat-treated material, tensile, compression and fatigue test has been performed. Considering results of mechanical properites of non-heat-treated material, it can replace heat-treated material. Therefore non-heat-treated material may be applied to cold forging.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2011년 춘계학술대회논문집
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• pp.183-186
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• 2011

There are numerous crashed deaths or near-miss accidents in everywhere. The outbreak place is not just developing countries such as India and Iran, but also leading countries including Japan and German. The crashed death of pedestrian seems to be an unavoidable accident. However, it was revealed in social psychology field that the accident can be treated as a kind of physical phenomenon. In this study, we apply discrete element method frequently used in the field of two-phase flow to pedestrian flow with collective behavior psychology. This approach is a field of social science and physics, called computational sociology. The acquired results show that emergency exit size can be related with the wall slope of the exit.

• 전기학회논문지
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• 제57권9호
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• pp.1652-1659
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• 2008

With the increase of huge amount of data in network systems, ultimate high-speed network has become an essential requirement. In such systems, the encryption and decryption process for security becomes a bottle-neck. For this reason, the need of hardware implementation is strongly emphasized. In this study, a mixed inner and outer round pipelining architecture is introduced to achieve high speed performance of ARIA hardware. Multiplexers are used to control the lengths of rounds for 3 types of keys. Merging of encryption module and key initialization module increases the area efficiency. The proposed hardware architecture is implemented on reconfigurable hardware, Xilinx Virtex2-pro. The hardware architecture in this study shows that the area occupied 6437 slices and 128 BRAMs, and it is translated to throughput of 24.6Gbit/s with a maximum clock frequency of 192.9MHz.

• Journal of Biosystems Engineering
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• 제25권1호
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• pp.11-18
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• 2000

In precision chemical application increment of biological efficacy with less chemical is the virtue. spraying rate and droplet size is closely related to biological efficacy. this study was performed to develope a spray-control-system that could control spraying rate and droplet size independently. Twin-fluid nozzles were selected and tested to certify if the nozzles were suitable for the objective of this study. Characteritics of the nozzles i.e., spraying rte and droplet size change u8nder the changes of spraying pressure and air pressure were statistically modeled. The model had I to 1 matching property between dependent variables and independent variables. Using the property and the model, inverse relationship could be determined between variables. A feedback spray control system was developed and tested with predetermined error of 5 % in pressure. The system showed 4 % error in spraying rate and 9 % error in droplets size. Performance of the system could be upgraded by fine tuning but, in practical sense keeping air pressure in the field sprayer was the bottle neck of commercialization of the spray system.

• 한국산업융합학회 논문집
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• 제2권2호
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• pp.147-153
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• 1999

An in-process extraction method of the ground surface roughness is a bottle-neck and essential field in conventional machining process. We define the D.A.R.F(Dimensionless Average Roughness Factor) that has a roughness characteristic of ground surface. D.A.R.F include the absolute average and the standard deviation values which are the analytic parameters of the AE(Acoustic Emission) signal generated during the grinding operation. The theoretical equation between the surface roughness and the D.A.R.F has been derived from the linear regressive analysis and verified its availability through the experimentation on the surface grinding machine.

• 소성∙가공
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• 제16권3호
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• pp.210-214
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• 2007

Manufacturing bulk nanostructured materials with least grain growth from initial powders is challenging because of the bottle neck of bottom-up methods using the conventional powder metallurgy via compaction and sintering. In the study, densification behavior of nano Cu powders during pressureless sintering was investigated using an in-situ optical dilatometer technique. The initial heating and steady temperature stages during the sintering of nano Cu powder compacts were observed. At the initial heating stage, the powder compact has many porosities and full densification needs high temperature and/or high pressure sintering. In the experimental analysis, changes in geometry and density were measured and discussed for optimal consolidation and densification by the in-situ optical dilatometer.

• 한국국방경영분석학회지
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• 제22권1호
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• pp.142-155
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• 1996

In this research, our objective is to develop a model which could evaluate the maintenance capability for a maintenance battalion in the mechanized division. To analyze the maintenance system, we obtained various data related to maintenance capability and described the maintenance process as a network type. This network type model is then translated to SLAM-II network model to simulate the system. The simulation model can be operated by using appropriate input data and simulation results are obtained. The simulation model can be applied in various way. Through the simulation we could find the bottle neck point in the maintenance process. Also the maximum capability of maintenance with on hand asset and the wartime supportability can be evaluated. The mode provides sensitivity analysis by changing various imput data such as the number of repairmen, repair time, failure rate and so on.

• 한국산학기술학회논문지
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• 제5권1호
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• pp.7-12
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• 2004

급액관리에 관련된 단계를 4단계로 나누었으며, 각 단계별 수분 이동 저항을 규명하고, 단계 중에서 급액 상황에 따라 관련 인자의 priority를 설정함으로써 펄라이트 자루재배할 경우 율속인자 중심의 적정 급액관리 기준을 제안하였다. 특히, 급액관리의 가장 중요한 율속인자인 뿌리까지의 수분도달거리를 최소한으로 하여 필요한 수분을 공급하는 과정과 역사성을 부여한 뿌리발달 조장이 가장 중요한 것으로 판명되었다.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.980-981
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• 2006

In this study, bottom-up type powder processing and top-down type SPD (severe plastic deformation) approaches were combined in order to achieve full density of Carbon nanotube (CNT)/metal matrix composites with superior mechanical properties by improved particle bonding and least grain growth, which were considered as a bottle neck of the bottom-up method using the conventional powder metallurgy of compaction and sintering. ECAP (equal channel angular pressing), the most promising method in SPD, was used for the CNT/Cu powder consolidation. The powder ECAP processing with 1, 2, 4 and 8 route C passes was conducted at room temperature.

• 한국시뮬레이션학회:학술대회논문집
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• 한국시뮬레이션학회 1998년도 추계학술대회 및 정기총회
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• pp.65-65
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• 1998

Manufacturing systems like a motor production process are analyzed using simulations than numerical analyses and/or heuristic methods due to their stochastic properties. The SME(small and medium enterprise) producing automotive motors that develop CIM systems to improve production performance is focused as an application site. We analyze and understand the system exactly using layout based simulation, and then we will suggest the initial feashible production-plan dependent on the layout to overcome weak-points of the current system(i.e., high WIPs, bottle-neck processes, due-date delays and etc.). And, solutions are suggested to increase performances of SMEs producing automotive motors in this paper. The simulation model built in this study is moedlled and analyzed with fully object-oriented methodology using SiMPLE++TM according to properties of production processes of the automotive motor. And, we will introduce ways to verify the model with developed templates for reusability when new needs will be occurred such as designing a new ship, extension or rearrangement of the system, change of production-plans, receiving urgent orders, and so on.