• Proceedings of the Korean Nuclear Society Conference
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• 1996.05a
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• pp.491-498
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• 1996

울진 3,4호기의 발전소컴퓨터계통(PCS)은 한국형 표준 원전의 컴퓨터 시스템으로 향후 완벽한 시스템으로의 구성을 위해서는 설계 개념의 재검토와 보완이 필요하다. 그 과정의 일환으로 국내 기술진에 의해 이미 상당부분의 기술을 습득한 월성 2,3,4호기의 발전소 제어 컴퓨터계통(DCCS)과 개념적인 비교를 통하여 PCS에서의 설계개선 사항을 구조적으로 제시하고자 하였다. 분석결과 PCS는 실시간 처리가 취약하였고, 몇몇 화면의 구성이 운전원의 요구를 만족시키기 위해 개선되어야 하였다. 또한, DCCS와의 공통적인 취약점으로는 개발환경의 낙후, 데이타 처리능력의 저조, 주변기기와의 데이터 통신에 많은 시간이 소요되며 호환성 및 확장성이 대체로 취약하였다. 이에 대한 대응방안으로는 시스템의 전격적인 교체보다는 부하 분산을 통한 실시간 처리와 점진적인 주변기기의 교체가 바람직하며, 이러한 점진적인 시스템의 교체시 고려사항과 운전원에게 제공되는 화면의 재구성 방안을 제시하였다.

• The Transactions of the Korea Information Processing Society
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• v.4 no.12
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• pp.3175-3184
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• 1997

To support large storage capacity and real-time characteristics of continuous media storage systems, we need to improve the performance of disk I/O subsystems. To improve the performance, we exploited buffer sharing scheme that reduces the number of disk I/Os. We utilized the advance knowledge of continuous media streams that is used to anticipate data demands, and so Promoting the sharing of blocks in buffers. In this paper, we proposed a buffer replacement algorithm that enables subsequent users requesting the same data to share buffer efficiently. The proposed algorithm manages buffers by utilizing reference interval information of blocks. In order to verify validity of the proposed algorithm, we accomplished simulation experiments and showed the results of performance improvements compared to traditional buffer replacement algorithms.

• Journal of the Korea Society of Computer and Information
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• v.19 no.11
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• pp.91-96
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• 2014

Since the sensors of Internet of Things (IOT) collect various data, the lifetime of sensor network is very important and the data should be aggregated efficiently. The contiguous collection by the certain sensors occurs an excessive battery consumption and successive transmission of same value of data should be avoided. To solve these things, we propose an weight-based cluster head replacement method that divides whole network into several grids and cluster head is selected by remaining energy, density of alive sensors and location of sensor. The aim of algorithm maximizes the lifetime of network. Our simulation results shows that the proposed method is very simple as well as balances energy consumption.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.4
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• pp.52-58
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• 2013

Replacement policy is one of the key factors determining the effectiveness of a cache. The LRU replacement policy has remained the standard for caches for many years. However, the traditional LRU has ineffective performance in zero-reuse line intensive workloads, although it performs well in high temporal locality workloads. To address this problem, We propose a new replacement policy; DCR(Dynamic Counter based Replacement) policy. A temporal locality of workload dynamically changes across time and DCR policy is based on the detection of these changing. DCR policy improves cache miss rate over a traditional LRU policy, by as much as 2.7% at maximum and 0.47% at average.

• KIISE Transactions on Computing Practices
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• v.21 no.1
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• pp.88-93
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• 2015

In modern computer systems, DRAM is commonly used as main memory due to its low read/write latency and high endurance. However, DRAM is volatile memory that requires periodic power supply (i.e., memory refresh) to sustain the data stored in it. On the other hand, PCM is a promising candidate for replacement of DRAM because it is non-volatile memory, which could sustain the stored data without memory refresh. PCM is also available for byte-addressable access and in-place update. However, PCM is unsuitable for using main memory of a computer system because it has two limitations: high read/write latency and low endurance. To take the advantage of both DRAM and PCM, a hybrid main memory, which consists of DRAM and PCM, has been suggested and actively studied. In this paper, we propose a novel page replacement algorithm for hybrid main memory. To cope with the weaknesses of PCM, our scheme focuses on reducing the number of PCM writes in the hybrid main memory. Experimental results shows that our proposed page replacement algorithm reduces the number of PCM writes by up to 80.5% compared with the other page replacement algorithms.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2009.04a
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• pp.213-216
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• 2009

유한요소모델개선기법은 계측된 동특성을 모사하는 구조해석모델을 구하는 방법으로서 손상탐지 및 구조건전도감시를 위해 효과적으로 이용될 수 있다. 유한요소모델개선기법에는 다양한 종류의 동특성데이터가 사용될 수 있는데, 본 연구에서는 고유진동수와 모드형상을 사용한 경우와 고유진동수와 주파수응답함수를 사용한 경우를 각각 사용해 실험실 규모의 구조물의 손상 위치 및 손상정도를 추정하였다. 4층 철골조의 골조구조물로서 진동대를 이용하여 원구조물에 백색잡음 가진실험을 실시한 후 손상의 모사를 위해 1층 부분의 보 부재를 작은 단면의 부재로 교체하고 동일한 실험을 반복하였다. 보 부재 교체 전 후에 계측된 데이터와 두 종류의 모델개선기법을 각각 적용하여 손상탐지를 실시한 후 그 정확도를 분석하였다.

• Proceedings of the Korean Information Science Society Conference
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• 2000.10a
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• pp.305-307
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• 2000

이 논문은 OGC에서 제안하는 3계층 구조의 웹 매핑 테스트베드(Web Mapping Testbed) 환경에서 각 계층간의 통신량과 데이터 변화량으로 인한 속도 저하 문제를 해결하고자 한다. 이를 위해, 다수의 클라이언트가 일정 시간 내에 공통으로 접근하는 지도 영역에 대한 미들웨어 컴포넌트들의 중복된 작업 수를 줄이기 위해 맵 서버 컴포넌트들 간에 공유 캐쉬를 사용하는 구조를 설계 및 구현한다. 이 논문에서 제시하는 미들웨어의 캐쉬 구조는 전체 데이터 세트의 영역을 일정 간격의 그리드 셀로 나누어 관리함으로써 캐쉬 단위의 관리 비용을 줄이고 캐쉬를 효율적으로 사용한다. 또한, 기존의 교체 전략 기법을 접목하여, 다수의 클라이언트의 관심 대상인 영역을 중심으로 캐쉬를 유지하기 위해 접근 빈도수와 최근 사용 시간을 고려한 교체 전략을 사용한다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.4
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• pp.61-68
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• 2017

Bridge decks are members that rapidly deteriorated due to various environmental factors such as heavy vehicle and deicing salt, etc. As the lifespan of bridges built in Korea increases, it is expected that the demand for replacing the deteriorated bridge decks will increase. In other countries, Accelerated Bridge Construction technology using precast decks is already actively being used as a countermeasure for replacement demand of deteriorated bridge decks. In this study, bridge decks deterioration models are proposed by collecting and analysing the condition index data of domestic bridge decks. Also, the future replacement demands of deteriorated bridge decks in terms of replacement time and replacement scale are predicted.

• Journal of the Korean Data and Information Science Society
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• v.22 no.4
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• pp.775-784
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• 2011

In this paper, we consider the periodic preventive maintenance model for repairable system following the expiration of non-renewing free replacement-repair warranty (NFRRW). Under this preventive maintenance model, we derive the expressions for the expected cycle length, the expected total cost and the expected cost rate per unit time. Also, we determine the optimal preventive maintenance period and the optimal preventive maintenance number by minimizing the expected cost rate per unit time. Finally, the optimal periodic preventive maintenance policy is given for Weibull distribution case.

• Journal of the Korea Society of Computer and Information
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• v.25 no.3
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• pp.11-17
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• 2020

In this paper, we propose practical results for cache replacement policy by measuring cache hit and search time for each replacement algorithm through cache simulation. Thus, the structure of each cache memory and the four types of alternative policies of FIFO, LFU, LRU and Random were implemented in software to analyze the characteristics of each technique. The paper experiment showed that the LRU algorithm showed hit rate and search time of 36.044% and 577.936ns in uniform distribution, 45.636% and 504.692ns in deflection distribution, while the FIFO algorithm showed similar performance to the LRU algorithm at 36.078% and 554.772ns in even distribution and 45.662% and 489.574ns in bias distribution. Then LFU followed, Random algorithm was measured at 30.042% and 622.866ns at even distribution, 36.36% at deflection distribution and 553.878ns at lowest performance. The LRU replacement method commonly used in cache memory has the complexity of implementation, but it is the most efficient alternative to conventional alternative algorithms, indicating that it is a reasonable alternative method considering the reference information of data.