• 한국신뢰성학회지:신뢰성응용연구
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• 제5권3호
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• pp.381-391
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• 2005

The level of reliability attained largely depends upon the investment in reliability growth programs during development phase. In order to find the relationship between reliability growth test time and BRTE(basic reliability tasks effectiveness) in a reliability improvement program that minimizes LCC in which contains the reliability growth cost, repair and replacement costs, and spare parts ordering costs in service with given service rate in management policy, the growth rate has been suggested proper LCC versus growth rate. This model employs the reliability growth projection with delayed fixes in avionic equipment based on AMSAA.

• 대한임베디드공학회논문지
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• 제7권3호
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• pp.129-134
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• 2012

The objective of cache is to reduce I/O access of physical storage device so that user accesses their data faster. Traditionally, the most important metric to measure the performance of cache is hitratio. Thus, when the cache maintains hitratio high, it is regarded as a good cache replacement policy. However, the cache miss latency is different when the storages are heterogeneous. Though the cache hitratio is high, if the cache often misses with low performance disk, then the user experiences low performance. To address this problem we proposed eviction cost estimation based cache management. In our result, the eviction cost estimation based cache management has 10~30% throughput improvement compared with LRU cache management.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 추계종합학술대회 논문집(3)
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• pp.51-54
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• 2000

Due to the emerging of high-speed network, lots of interests of access to remote data have increased. Those interests motivate using of Cooperative Caching that uses remote cache like local cache by sharing other clients' cache. The conventional algorithm like GMS(Global Memory Service) has some disadvantages that occurred bottleneck and decreasing performance because of exchanges of many messages to server or manager. On the other hand, Hint-based algorithm resolves a GMS's server bottleneck as each client has hint information of all blocks. But Hint-based algorithm also causes some problems such as inaccurate information in it, if it has too old hint information. In this paper, we offer the policy that supplement bottleneck and inaccuracy； by using file identifier that can search for the lookup table and by exchanging oldest block information between each client periodically.

• 산업경영시스템학회지
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• 제23권58호
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• pp.17-27
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• 2000

In FMS where tool movement policy is adopted, a mathematical model has been developed which determines the selection of a tool type for each operation and tool loading-part assignment simultaneouly. The objective is to minimize the total cost of operation including machining time cost, tool cost, tool replacement and loading time cost, and tool change time cost. Due to the complexity of the problem, an approximate solution procedure has been developed utilizing the special structure of the model. Tool selection was determined first to allocate one tool type to each operation considering more than one tool type alternatives for each operation. Tool loading-part assignment was determined to minimize tile total number of tool changes due to part mix based on the tool selection.

• 대한임베디드공학회논문지
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• 제9권1호
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• pp.25-32
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• 2014

In this paper, we proposed a partial-way set associative cache memory with an effective memory access time and low energy consumption. In the proposed set-associative cache memory, it is allowed to access only a 2-ways among 4-way at a time. Choosing ways to be accessed is made dynamically via the least significant two bits of the tag. The chosen 2 ways are sequentially accessed by the way selection bits that indicate the most recently referred way. Therefore, each entry in the way has an additional bit, that is, the way selection bit. In addition, instead of the 4-way LRU or FIFO algorithm, we can utilize a simple 2-way replacement policy. Simulation results show that the energy*delay product can be reduced by about 78%, 14%, 39%, and 15% compared with a 4-way set associative cache, a sequential-way cache, a way-tracking cache, and a way cache respectively.

• 한국경영과학회지
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• 제10권2호
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• pp.54-64
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• 1985

Biomass conversion processes have the potential for satisfying approximately 25% of the national demand for methane gas. At the current time very littel analytical work has been done to optimally design and operate the production facilities associated with these processes. This study was motivated by the high cost of these proposed systems. The biomass in storage decays (exponentially) with time while the batch methane production rate decreases (exponentially) over time. The basic problem is to determine the optimal residence times for batches in the anaerobic degester to maximize total production over a fixed planning horizon. The analysis characteries the form of the optimal policy and presents efficient algorithm for obtaining this solution.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2001년도 가을 학술발표논문집 Vol.28 No.2 (3)
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• pp.643-645
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• 2001

인터넷이라는 환경이 우리의 생활의 일부로 자리잡으면서, 급속히 늘어난 사용자들의 요구는 그 만큼 네트워크의 현저한 부하증가를 일으키고 네트워크의 성능저하를 유발하며 속도 면에서도 빠른 응답을 원하는 사용자들의 욕구를 충족시키지 못하게 된다. 이에 대한 하나의 대응책이, 프락시 서버를 사용함으로써 네트워크 대역폭을 효과적으로 절약하고 서버 측의 부하를 감소시키며 사용자의 요청에 대한 빠른 응답이 가능하게 하는 것이다. 그러나 프락시 서버는 제한된 캐시용량 때문에 새 개체를 위한 공간확보를 위해 기존 개체를 제거해야 하는데, 캐시의 성능을 최대화하도록 하는 효율적인 캐시대체 정책이 필요하다. 기존의 대체정책이 캐시성능판단의 두 기준인 히트율(Hit Rate)과 바이트히트율(Byte Hit Rate)을 만족시키지 못하던지 흑은 불필요한 개체에 공간을 낭비하는 등 최대한치 공간활용을 못하는 단점을 가지고 있다. 본 논문에서는 캐시를 상위층과 하위충의 2단계로 나누어 운용하면서, 상위층은 분할된 여러개의 파티션으로 관리하여 히트율과 바이트율을 높게 유지하고 하위층은 상위의 각각의 파티션들에 추가적으로 필요한 캐시공간을 제공함으로서 동적인 파티션공간분할 효과를 제공하는 프락시 서버의 캐시구조와 캐시대체정책을 제안한다.

• Smart Structures and Systems
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• 제6권9호
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• pp.1041-1056
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• 2010

This paper investigates the possibility of a strategy for an automatic full recover of a structural component undergoing loading-unloading (fatigue) cycles: full recover means here that no replacement is required at the end of the mission. The goal is to obtain a material capable of self healing earlier before the damage becomes irreversible. Attention is focused on metallic materials, and in particular on shape memory alloys, for which the recovering policy just relies on thermal treatments. The results of several fatigue tests are first reported to acquire a deep understanding of the physical process. Then, for cycles of constant amplitude, the self-healing objective is achieved by mounting, on the structural component of interest, a suitable microcontroller. Its input, from suitable sensors, covers the current stress and strain in the alloy. The microcontroller elaborates from the input the value of a decisional parameter and activates the thermal process when a threshold is overcome.

• 디지털융복합연구
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• 제3권2호
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• pp.131-142
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• 2005

Under the internet age, the competition among recruiting intermediaries including online and offline players has been intensified for several years. Therefore, their business processes or business models have also been transformed to be able to earn the competitive advantages. For these reasons, the traditional players like offline-based recruiting companies have willingly or unwillingly experienced the competitive disadvantages on the recruit battle ground. The online recruiting intermediaries, who newly participated in this industry and based on the internet environment, however, seized on the competitive advantages with the richness and the reach traits of online media. Under this context, the offline traditional intermediaries, who have been threatened by new online entries, must make a replacement of traditional trading mechanisms with alternative trading mechanisms like IT-enabled intermediaries. In this study by exploratory approach, we investigate the phases of transformation of the traditional recruiting intermediaries, changes in business strategies of offline-based firms, and impacts of online media in e-recruiting industry.

• Journal of Computational Design and Engineering
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• 제2권2호
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• pp.119-127
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• 2015

In the case of a high-valuable asset, the Operation and Maintenance (O&M) phase requires heavy charges and more efforts than the installation (construction) phase, because it has long usage life and any accident of an asset during this period causes catastrophic damage to an industry. Recently, with the advent of emerging Information Communication Technologies (ICTs), we can get the visibility of asset status information during its usage period. It gives us new challenging issues for improving the efficiency of asset operations. One issue is to implement the Condition-Based Maintenance (CBM) approach that makes a diagnosis of the asset status based on wire or wireless monitored data, predicts the assets abnormality, and executes suitable maintenance actions such as repair and replacement before serious problems happen. In this study, we have addressed several aspects of CBM approach: definition, related international standards, procedure, and techniques with the introduction of some relevant case studies that we have carried out.