• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.6
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• pp.1289-1300
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• 2011

In recent computer systems with high-performance, users execute programs needing large memory and programs intensively accessing files simultaneously. Such a large memory requirement makes virtual memory systems access swap spaces in disk, and intensive file accesses require file systems to access file system partitions in disk. Executing the two kinds of programs at once incurs large disk seeks between swap spaces and file system partitions frequently. To solve the problem, this paper proposes a new scheme called SAF to create several swap spaces in a file system partition, where pages to be paged out are stored. When a page is paged out, the scheme stores the page to one of the swap spaces close to a disk location where the most recently accessed file is located. The chosen swap space in the file system partition is closer to the disk location than the traditional swap space, so that our scheme can reduce the large disk seek time spent to move to the traditional swap space in paging out a page. The experiment of our scheme implemented in FreeBSD 6.2 shows that SAF reduces the execution time of several benchmarks over FreeBSD ranging from 14% to 42%.

• Proceedings of the Korean Information Science Society Conference
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• 2002.10c
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• pp.376-378
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• 2002

가상 메모리 관리에서 가장 근 문제점은 느린 보조기억 장치의 속도와 빠른 주기억장치의 속도 차이에서 나타나는 성능 저하라고 할 수 있다 요구 페이징 기법에서 Page Fault가 일어나면 페이지 교체 정책에 의해 필요 없는 page들을 swap device로 이동을 시킨다. 이때 느린 보조기억장치의 접근 속도로 인한 응답시간의 지연은 전체적인 시스템 성능의 저하를 초래한다. 그래서 Swap Device로의 접근 횟수와 페이지의 크기를 줄일 수 있다면 Page Out되는 응답시간을 높일 수 있을 것이다. 따라서 본 논문에서는 가상 메모리 압축 시스템을 설계하여 Swap Out 되는 시간을 줄여 시스템의 전체적인 성능 향상을 위한 시스템을 구현한다.

• Proceedings of the KIPE Conference
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• 2018.11a
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• pp.177-178
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• 2018

본 논문에서는 직렬형 Hot-Swap ESS(Energy Storage System)를 구성하는 전력 변환 시스템에서 전류 센서의 옵셋 오차가 제어 성능에 미치는 영향에 대해 살펴보았다. 양방향 DC-DC 컨버터와 DC-AC 인버터에서 전류 센서 옵셋 오차의 영향에 대해 분석하고, 컴퓨터 모의 시험을 진행하여 그 특성을 파악하였다.

• Proceedings of the KIEE Conference
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• 2005.10b
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• pp.237-239
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• 2005

In this paper PLC Power Circuit with Hot-Swap Function is proposed for stable power supplies. The power modules of the proposed devices are implemented by CRM flyback converter using new synchronous rectifier circuit for high efficiency. By a variable switching frequency controller, this converter is operated with a reduced turn-on switching loss. Also, the load current in these power modules are shared by auto master / slave method using Outer loop. The proposed devices are analyzed in detail and optimized for high performance. Experimental results for a 100W power module at the variable switching frequency of 30$^{\sim}$70kHz were obtained to show the performance of the proposed device.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.2
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• pp.255-262
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• 2015

In the absence of a deterministic algorithm for economic load dispatch optimization problem (ELDOP), existing algorithms proposed as solutions are inevitably non-deterministic heuristic algorithms. This paper, therefore, proposes a balance-and-swap algorithm to solve an ELDOP. Firstly, it balances the initial value to ${\Sigma}P_i=P_d$ by subsequently reducing power generation for each adult-step and baby-step and selects the minimum cost-generating method. Subsequently, it selects afresh the minimum cost-generating method after an optimization of the previously selected value with adult-step baby-step swap and giant-step swap methods. Finally, we perform the $P_i{\pm}{\beta}$, (${\beta}=0.1,0.01,0.001,0.0001$) swap. When applied to the 3 most prevalently used economic load dispatch problem data, the proposed algorithm has obtained improved results for two and a result identical to the existing one for the rest. This algorithm thus could be applied to ELDOP for it has proven to consistently yield identical results and to be applicable to all types of data.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.2
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• pp.61-66
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• 2023

As the use of smartphones expands to various areas and the level of multitasking increases, the support of swap is becoming increasingly important. However, swap support in smartphones is known to cause excessive storage traffic, resulting in memory thrashing. In this paper, we analyze how the thrashing of swaps that occurred in early smartphones has changed with the advancement of smartphone hardware. As a result of this analysis, we show that the swap thrashing problem can be resolved to some extent when the memory size increases. However, we also show that thrashing still occurs when the number of running apps continues to increase. Based on further analysis, we observe that this thrashing is caused by some hot data and suggest a way to solve this through an NVM-based architecture. Specifically, we show that a small size NVM with judicious management can resolve the performance degradation caused by smartphone swap.

• The Korean Journal of Financial Management
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• v.24 no.2
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• pp.113-145
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• 2007

In this paper, we examine whether the poor performance of distressed firms where banks take equity may occur due to agency problems in banks. By adopting the debt-equity swap, the bank can effectively postpone the occurrence of bad loans form the failure of the distressed firm. As a result, firms with more debt will be more likely to obtain debt-equity swap, regardless of their probabilities of revival. This is not because they are more profitable, but because they have more debt and thus it poses greater risk to the bank. We empirically look into these predictions with the data of 44 workout firms and find the following results. First, debt-equity swap appears to be more applicable especially when the distressed firms are large and when BIS of related banks is low. Specifically, the conditional probability of 'large firms' based on debt-equity swap is 65.52% and the conditional probability of 'bad banks' based on debt-equity swap is 75.86%. Also, as predicted, the performance of these debt-equity firms is poorer than that of non debt-equity firms. The conditional probability of 'large firms' based on posterior failure is 84.62% and the conditional probability of 'bad banks' based on posterior failure is 84.62%. This is consistent with our predictions and is also confirmed through results of the logit regression analysis. Second, when the restructuring is led by 'good banks', the performance of equity-swap firms is superior to that of non equity-swap firms. This result is consistent with that of James(1995). Hence, we can conclude that there may be some agency problems in restructuring distressed firm-especially when distressed firms are large and banks are bad. And these agency problems can reconcile the difference between James' results and Park, Lee, and Jang's.

• Journal of Korea Water Resources Association
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• v.54 no.11
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• pp.925-932
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• 2021

A drought-flood abrupt alternation event is an overlapping extreme event that is harder to cope with than a single event of drought and flood. It is also expected to have a significant adverse impact on ecosystems as well as industries and agriculture. However, there has not yet been a comprehensive study that characterizes the drought-flood abrupt alternation events in Korea. Therefore, this study employed a standard weighted average precipitation (SWAP) index, which is efficient to analyze not only individual events of drought and flood but also the drought-flood abrupt alternation events considering various time scales. The SWAP standardized the weighted average precipitation (WAP) by adding temporal weights to the precipitation. The SWAP indices were calculated for middle-sized watersheds of the Han River basin using the area average precipitation during 1966 and 2018. The severity K was calculated to represent the relative regional severity considering normal rainfalls, and used to characterize the drought-flood abrupt alternation in the study areas. The results indicated that 20 of the 30 middle-sized watersheds in the Han River basin were confirmed to increase the severity of drought-flood abrupt alternation over time. Considering the frequency and severity of drought-flood abrupt alternation events in each watershed, vulnerable areas and dangerous areas due to drought-flood abrupt alternation were identified, for example, the Upstream Namhan River (#1001).

• JSTS:Journal of Semiconductor Technology and Science
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• v.15 no.1
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• pp.68-76
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• 2015

Phase-change memory (PCM) is a promising technology that is anticipated to be used in the memory hierarchy of future computer systems. However, its access time is relatively slower than DRAM and it has limited endurance cycle. Due to this reason, PCM is being considered as a high-speed storage medium (like swap device) or long-latency memory. In this paper, we adopt PCM as a virtual memory swap device and present a new page replacement policy that considers the characteristics of PCM. Specifically, we aim to reduce the write traffic to PCM by considering the dirtiness of pages when making a replacement decision. The proposed replacement policy tracks the dirtiness of a page at the granularity of a sub-page and replaces the least dirty page among pages not recently used. Experimental results with various workloads show that the proposed policy reduces the amount of data written to PCM by 22.9% on average and up to 73.7% compared to CLOCK. It also extends the lifespan of PCM by 49.0% and reduces the energy consumption of PCM by 3.0% on average.

• Journal of Microbiology and Biotechnology
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• v.15 no.6
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• pp.1377-1383
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• 2005

In a cDNA microarray experiment using Cy3 and Cy5 as labeling agents, particularly for the direct design, cDNAs from some genes incorporate one dye more efficiently than the other, which is referred to as the gene-specific dye bias. Dye-swaps, in which two dyes are switched on replicate arrays, are commonly used to control the gene-specific dye bias. We developed a simple procedure to extract the gene-specific dye bias information from a partial dye swap experiment. We detected gene-specific dye bias by identifying outliers in an X-Y plane, where the X axis represents the average log-ratio from two sets of dye swap pairs and the Y axis exhibits the average log ratio of four forward labeled arrays. We used this information for detecting differentially expressed genes, of which the additionally detected genes were validated by real-time RT-PCR.