• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1998년도 춘계학술발표회논문집(1)
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• pp.264-270
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• 1998

This research broadens the prime concern of nuclear power plant operations from safe performance to both economic and safe performance. First emergency diesel generator is identified as one of main contributors for the lost plant availability through the review of plants forced outage records. The framework of an integrated architecture for performing modern on-line condition for operational availability improvement is configured in this work. For the development of the comprehensive sensor networks for complex target systems, an integrated methodology incorporating a structural hierarchy, a functional hierarchy, and a fault-system matrix is formulated. The second part of our research is development of intelligent diagnosis and maintenance advisory system, which employs Bayesian Belief networks (BBNs) as a high level reasoning tool incorporating inherent uncertainty use in probabilistic inference. Our prototype diagnosis algorithms are represented explicitly through topological symbols and links between them in a causal direction. As new evidence from sensor network development is entered into the model especially, our advisory of system provides operational advice concerning both availability and safety, so that the operator is able to determine the likely modes, diagnose the system state, locate root causes, and take the most advantageous action. Thereby, this advice improves operational availability

• 한국컴퓨터정보학회:학술대회논문집
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• 한국컴퓨터정보학회 2008년도 제38차 하계학술발표논문집 16권1호
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• pp.217-224
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• 2008

본 논문에서는 기술자격시스템에 대한 관리 운영상의 효율성을 향상시키기 위하여 내부관리시스템을 설계하고 구현하였다. 비정기성 기술자격시스템은 정보처리 관련기업에 개발 및 구현에 대한 전체적인 사항을 위탁업무로 수행하고 처리 결과에 대한 자료를 시행기관에서 인수하여 내부업무를 처리한다. 이러한 관리체계는 추가적 요구정보에 대한 재처리에 많은 문제점을 내포한다. 부가적인 추가적 요구사항에 대하여 재개발 절차가 필요하며 효율적인 업무처리와 관리체계를 수행하는데 불안정한 요소들을 가지고 있는바, 이러한 문제점을 해결하기 위한 방안으로 특수 자격 분야에 시범적으로 적용한 내부관리시스템을 제안하였다. 제안된 내부관리 시스템의 기능 평가는 시뮬레이션 방식으로 최소 규모의 파일럿시스템에서 구현 기술을 적용하고 검증 한 후 실시간 기술자격 시험에 시범 적용한 결과 처리 과정상의 안정성과 실용성이 인증되어 대단위 자격시스템에 확대 적용할 계획이다. 위탁기관과 연계하여 부가적 요구정보 처리 시 발생되는 추가 개발기간에 대한 문제점을 해결하였으며 안정적인 시스템 운영상태와 최대의 효율성을 보여주었다. 특히 내부관리시스템을 사용하는 전문가와 비전문가그룹으로 이루어진 자격시행기관의 시스템 평가에서 사용자 편리성과 확장성 부문에 탁월한 평가를 도출하였다. 본 논문에서 설계 및 구현한 내부관리 시스템은 다양한 방식과 구성요소를 통합하여 공통영역을 표준화 한 후, 체계적으로 실시간 자격관리시스템에 적용 될 수 있을 것으로 분석되었다.

• 태양에너지
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• 제19권4호
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• pp.11-20
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• 1999

The study on ice thermal storage system is to improve total system performance and increase the economical efficiency in actual air-conditioning facilities. To obtain the high charging and discharging efficiencies in ice thermal storage system, the improvement of thermal stratification is essential, therefore the process flow must be piston flow in the cylindrical type. In the influence of the inlet port type, the inflowing water in the distributor type diffuses through the whole storage tank more than in the slot type. In case of the flow process in the ice storage tank, the upward flow type in the charging process and the downward flow type in the discharging process make the stratification well, thereby the loss of energy wored be smaller. The influence of the inlet temperature difference and the change of the inlet flow rate is intensive when the temperature difference is larger, the flow rate is smaller in case of charging and the results are opposite in case of discharging with the reason that the good coduction condition. The total effeciency of the ice thermal storge system is 73% on condition that the porosity in the thermal storage tank is 0.55. This result shows that cylinderical ice storage tank has better storage capacity than rectangular type in case of the same porosity.

• 한국컴퓨터정보학회논문지
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• 제22권9호
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• pp.1-8
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• 2017

In this paper, we propose a file system for flash memory which remedies shortcomings of existing flash memory file systems. Besides supporting large block size, the proposed file system reduces time in initializing file system significantly by adopting logical address comprised of erase block number and bitmap for pages in the block to find a page. The file system is suitable for embedded systems with limited main memory since it has small in-memory data structures. It also provides efficient management of obsolete blocks and free blocks, which contribute to the reduction of file update time. Finally the proposed file system can easily configure the maximum file size and file system size limits, which results in portability to emerging larger flash memories. By conducting performance evaluation studies, we show that the proposed file system can contribute to the performance improvement of embedded systems.

• 마케팅과학연구
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• 제8권
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• pp.375-402
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• 2001

본 연구는 통합물류정보시스템(물류정보시스템의 기능별 활용 수준, 물류활동 연계, 물류조직구조, 물류전략 유형)이 물류성과에 미치는 영향 요인에 대해 실증적으로 조사하였다. 이를 위하여 조사한 결과 다음과 같은 시사점을 얻을 수 있었다. 기업적인 측면에서 물류정보시스템을 운영은 하고있으나 기능별 활용 수준이 낮고 각 시스템을 독립적으로 운영하고 있으며, 사내와 고객 그리고 공급자 연계가 잘 이루어지지 못 하고 있는 실정이다. 그리고 대부분의 기업들은 시스템 기기들이 도입 초기 단계 또는 기능별 정착 단계에 있다. 장기적인 관점에서 물류합리화를 위해 기업경쟁력을 강화시키기 위해서는 물류 각 기능별로 독립적으로 구축된 시스템보다는 전사적인 차원에서 기능간 연계가 이루어지는 통합적인 물류정보시스템이 구축되어야 하고 이러한 통합적 관점에서 또한 공급 사슬관리가 이루어져야 한다. 이를 통하여 물류운영의 효과성과 효율성을 크게 개선할 수 있고 구매비용, 수송비용, 재고 및 창고 관리 비용간의 상층관계를 원활하게 해결할 수 있다. 그리고 공급사슬 네트워크상의 파트너들과의 긴밀한 상호협조를 통하여 최종 고객에게 제공하는 서비스를 제고시킬 수 있으며 공급사슬상의 물류비용을 절감시킬 수 있다.

• 산업경영시스템학회지
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• 제24권69호
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• pp.13-22
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• 2001

The efficient quality assurance system to prevent mixed assembly in introduced in this paper, It supports JIT(Just-In-Time) based Kanban and demand pull system. A new system is designed for the synchronized production and quality assurance using barcode and production kanban card, And the performance improvement method for the stable and fast response of the proposed system is suggested in this paper also. As the result of the proposed system, we improved production status visibility and quality traceability.

• 한국전산유체공학회지
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• 제17권4호
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• pp.56-68
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• 2012

Nowadays, Unmanned Combat Air Vehicle(UCAV) has become an important aircraft system for the national defense. For its efficiency and survivability, shape optimization of UCAV is an essential part of its design process. In this paper, shape optimization of UCAV was processed for aerodynamic performance improvement and Radar Cross Section(RCS) reduction using Multi Objective Genetic Algorithm(MOGA). Lift and induced drag, friction drag, RCS were calculated using panel method, boundary layer theory, Physical Optics(PO) approximation respectively. In particular, calculation applied Radar Absorbing Material(RAM) was performed for the additional RCS reduction. Results are indicated that shape optimization is performed well for improving aerodynamic performance, reducing RCS. Further study will be performed with higher fidelity tools and consider other design segments including structure.

• 대한기계학회논문집
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• 제18권11호
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• pp.2817-2824
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• 1994

A torque split type multi-pass CVT(MPC) system consiting of CVT and planetary gear train with 4 clutches was suggested to overcome the inherent inferior acceleration performance of CVT. Also, a shifting algorithm of MPC was suggested for the two driving modes : (1) power mode and (2) economy mode. By using the shifting algorithm and the MPC vehicle dynamic model, numerical simulations were performed to estimate the performance of the MPC vehicle. Simulation results showed that comparing the performance of the conventional 4-speed automatic transmission, an improvement in acceleration can be obtained by MPC for the power mode and 31% improvement in fuel economy for the economy mode.

• International Journal of Automotive Technology
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• 제1권2호
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• pp.89-94
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• 2000

As a promising catalyst reducing cold start emissions of automobiles, a photocatalyst systems has been studied. Since the photocatalyst is only activated by UV wavelength light, it needs no heat energy like a conventional TWC, therefore no light-off time. However, as a cold temperature catalyst to treat cold start emissions of a vehicle, previous studies on characteristic of photocatalyst have room for improvement in terms of performance and durability investigated from the viewpoints of performance and durability improvement. Eleven different coating samples were prepared with the combination of six kinds of additives and two kinds of photocatalyst materials. Then these samples were aged with a hydrothermal aging process. The performance of these samples was measured on a model gas apparatus with simulated exhaust gases. The durability was also analyzed with X-ray diffraction meter.

• 한국인터넷방송통신학회논문지
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• 제10권5호
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• pp.121-125
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• 2010

본 논문에서는 T-DMB 워터마킹 시스템에 길쌈 부호화기를 적용하여 부가 정보를 전송하는 알고리즘의 성능을 개선하는 방법에 알아보았다. 길쌈 부호화기를 제안된 기법에 적용함으로써 오류 성능을 개선할 수 있었고, 그로 인해 부가 정보 전송량이 증가하는 효과를 가져왔다. 모의실험을 통하여 채널 부호화기가 적용된 제안 기법의 성능을 분석하였고 유용성을 확인하였다.