• Proceedings of the Korean Information Science Society Conference
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• 2000.10a
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• pp.364-366
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• 2000

컴포넌트 기반의 개발과 컴포넌트 개발에 대한 관심이 높아지면서 이를 위하 개발 방법론과 개발 도구들의 도입이 확산되고 있다. 또한 컴포넌트의 재사용 범위를 확장시키기 위해 컴포넌트 개발 시 나타나는 Hot Spot 처리를 위한 분석, 설계 기법에 대한 관심이 높아지고 있다. 따라서 본 논문에서는 이러한 분석, 설계기법을 이용하여 융통적인 계층적 접근 권한에 대한 분석, 설계 모델을 제시한다. 본 논문에서는 다지인 모델링을 위한 표기법으로서 객체지향 모델링 기법인 UML(Unified Modeling Language)를 이용하여 모델링 한다.

• Proceedings of the Korean Information Science Society Conference
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• 1998.10b
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• pp.632-634
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• 1998

기존의 객체기술은 재사용성과 유지보수 측면에서 많은 문제를 안고 있다. 해결책으로 여러 가지가 제시되었으나 그 중 객체지향 프레임웍을 기반으로 하여 시스템의 복잡도와 급증하는 크기 그리고 개방형 시스템의 구축 시에 발생하는 여러 가지 난제를 해결하고자 하였다. 그러나 프레임웍 연구는, 대부분 컴포넌트나 객체단위의 재사용성을 극대화하는데 초점이 맞추어져 있어서 소프트웨어의 유연성(flexibility)에 관한 문제는 별로 다루어지지 않고 있는 것이 현실이다. 따라서 본 논문은 소프트웨어 시스템 아키텍쳐 수준에서와 유지보수 차원의 유연성을 확보하는 방안으로 '핫 스팟 어댑터 모델'을 제안하고자 한다.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.8
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• pp.15-21
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• 1996

This paper describes data placement schemes that provide uniform and balanced to multiple disks load for retrievals of VBR (variable bit rate) video at varying retrieval speeds. To support maximum concurent users at arbitrary-speed playbacks in a disk-arry based system, the hot spot disks should be carefully avoided. In this paper, we extend the proposed scheme, prime round-robin(PRR), for VBR video. In addition, we have compared the performance of PRR and PRR (PRR extension).

• Information and Communications Magazine
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• v.31 no.3
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• pp.79-84
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• 2014

무선 통신 데이터 사용량은 꾸준히 증가하고 있는데, 주파수 자원이 한정되어 있어서 무선 통신망의 용량을 키우려면 셀(cell)을 작게 하여 동일 면적에 더 많은 셀을 구축해야 한다. 이를 효율적으로 구축하기 위한 방안으로 C-RAN 개념이 도입되었다. 본고에서는 C-RAN 아키텍쳐에 대해 소개하고, C-RAN의 특장점을 성능 관점, 설치 운용 관점 및 3GPP Release 10 이후의 기술 적용 관점에서 살펴보고, Super Hot Spot에서의 C-RAN 응용 사례와 향후 발전 전망에 대해 논의한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2001.04a
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• pp.535-538
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• 2001

본 논문은 작은 fanout에 대한 불공정성과 hot-spot의 문제를 해결하기 위해 공정하게 입력포트에 접근하여 복사망으로 들어갈 수 있는 멀티캐스트 스위치를 제안하고자 한다. 제안된 스위치는 큰 fanout에 대한 작은 fanout을 가진 입력포트에 도착한 패킷의 불공정한 대우를 해결하여 시스템 전체 지연시간을 줄여 산출량을 극대화할 수 있다.

• Proceedings of the Korean Information Science Society Conference
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• 1999.10a
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• pp.460-462
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• 1999

소프트웨어의 경제성, 시장 경쟁력 확보를 위한 소프트웨어의 재사용은 소프트웨어 공학의 주요 이슈가 되고 있다. 그중 컴포넌트와 컴포넌트 기반의 소프트웨어 개발은 재사용성을 확보할 수 있는 가장 주목 받는 방안으로 제시되고 있으며 많은 기법이나 지침들이 제안되고 있다. 본 논문에서는 컴포넌트 개발에서 UML에 기반하여 컴포넌트의 인터페이스를 추출하는 기법을 제시하고자 한다. 분석 단계에서 컴포넌트의 식별이 이루어졌다고 가정하고 분석 단계에서 나온 산출물 중, Use Case 모델과 클래스 다이어그램을 이용하여 컴포넌트의 메소드들을 식별하고, 인터페이스로 정의한다. 그리고 사용자요구사항에 근거하여 Hot Spot을 식별한 후, 컴포넌트의 커스터마이즈를 위한 메소드와 인터페이스를 정의한다.

• Journal of Advanced Marine Engineering and Technology
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• v.18 no.1
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• pp.114-122
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• 1994

A cold temperature control system for the BAF(batch annealing furnace) has been established in order to reduce energy consumption to imrpove productivity and stabilize the properties of products. Therefore we confirmed a relation between annealing cycle time and atmospheric gas, changing annealing cycle time according to BAF temperature with time during heating and actual temperature measurements cold spot during soaking. The results of the temperature variation effect on the batch annealing are as follows. 1) Cooling rate is increasing gradually with increasing atmospheric gas flow, but heating rate is hardly increasing without atmospheric gas component. Heating time is reduced to one half with increasing atmospheric gas flow rate and changing of atmospheric gas component from HNx to Ax gas and annealing cycle time is reduce to 2.7 times. 2) With enlarging the difference between furnace temperature and soaking temperature at the HNx BAF, heating time becomes short, but cooling time is indifferent. 3) If temperature difference of 300.deg. C in the temperature change of cold spot according to the annealing cycle control temperature, Hi-CON/H2BAF is interchanging at each other at 26hours, but HNxBAF at 50 hours. 4) Soaking time at batch annealing cycle determination is made a decision by the input coil width, and soaking time for quality homogenization of 1219 mm width coil must be 2.5 hours longer then that of 914mm width coil for the same coil weight at Hi-CON/H2BAF. But, it is necessary to make 2 hours longer at HNxBAF.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.483-488
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• 2003

Frictional heating in brakes causes thermoelastic distortion of the contacting bodies and hence affects the contact pressure distribution. The resulting thermo-mechanical coupling can cause thermoelastic instability (TEI) if the sliding speed is sufficiently high, leading to non-uniform heating called hot spots and low frequency vibration known as hot judder. The vibration of brakes to the known phenomenon of frictionally-excited thermoelastic instability is estimated studying the interface temperature and pressure evolution with time. A simple model has been considered where a layer with half-thickness ${\alpha}$ slides with speed V between two half-planes which are rigid and non-conducting. The advantage of this properly simple model permits us to deduce analytically the critical conditions for the onset of instability, which is the relation between the critical speed and the growth rate of the interface temperature and pressure. Symmetrical component of pressure and temperature distribution at the layer interfaces can be more unstable than antisymmetrical component. As the thickness ${\alpha}$ reduces, the system becomes more apt to thermoelastic instability. Moreover, the evolution of the system beyond the critical conditions has shown that even if low frequency perturbations are associated with low critical speed, it might be less critical than high frequency perturbations if the working sliding speed is much larger than the actual critical speed of the system.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.1
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• pp.114-121
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• 2004

Frictional heating in brakes causes thermoelastic distortion of the contacting bodies and hence affects the contact pressure distribution. The resulting thermo-mechanical coupling can cause thermoelastic instability (TEI) if the sliding speed is sufficiently high, leading to non-uniform heating called hot spots and low frequency vibration known as hot judder. The vibration of brakes to the known phenomenon of frictionally-excited thermoelastic instability is estimated studying the interface temperature and pressure evolution with time. A simple model has been considered where a layer with half-thickness$\alpha$slides with speed V between two half-planes which are rigid and non-conducting. The advantage of this properlysimple model permits us to deduce analytically the critical conditions for the onset of instability, which is the relation between the critical speed and the growth rate of the interface temperature and pressure. Symmetrical component of pressure and temperature distribution at the layer interfaces can be more unstable than antisymmetrical component. As the thickness $\alpha$ reduces, the system becomes more apt to thermoelastic instability. For perturbations with wave number smaller than the critical$m_{cr}$ the temperature increases with m vice versa for perturbations with wave number larges than $m_{cr}$ , the temperature decreases with m.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.10
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• pp.1179-1185
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• 2011

Cold and hot-rolled carbon steel sheets are commonly used in railroad cars or commercial vehicles such as the automobile. The sheets used in these applications are mainly fabricated by spot welding, which is a type of electric resistance welding. However, the fatigue strength of a spot-welded joint is lower than that of the base metal because of high stress concentration at the nugget edge of the spot-welded part. In particular, the fatigue strength of the joint is influenced by not only geometrical and mechanical factors but also the welding conditions for the spot-welded joint. Therefore, there is a need for establishing a reasonable criterion for a long-life design for spot-welded structures. In this thesis, ${\Delta}P-N_f$ relation curves have been used to determine a long-life fatigue-design criterion for thin-sheet structures. However, as these curves vary under the influence of welding conditions, mechanical conditions, geometrical factors, etc. It is very difficult to systematically determine a fatigue-design criterion on the basis of these curves. Therefore, in order to eliminate such problems, the welding residual stresses generated during welding and the stress distributions around the weld generated by external forces were numerically and experimentally analyzed on the basis of the results, reassessed fatigue strength of gas welded joints.