• Journal of KIISE
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• v.43 no.2
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• pp.177-185
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• 2016

In this paper, we propose a hybrid write buffer architecture comprised of DRAM and NVRAM on SSD and a write buffer algorithm for the hybrid write buffer architecture. Unlike other write buffer algorithms, the proposed algorithm considers read pages as well as write pages to improve the performance of storage devices because most actual workloads are read-write mixed workloads. Through effectively managing NVRAM pages, the proposed algorithm extends the endurance of SSD by reducing the number of erase operations on NAND flash memory. Our experimental results show that our algorithm improved the buffer hit ratio by up to 116.51% and reduced the number of erase operations of NAND flash memory by up to 56.66%.

• Journal of Digital Contents Society
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• v.10 no.3
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• pp.395-400
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• 2009

The wide spread of the Internet service has brought in web GIS development. But, there are problems of the user access latencies, the network traffic, and the server overload in Internet Geographic Information System because spatial data are transferred in large volumes. In this paper, I propose a cache algorithm on client side to solve the above problems. The proposed algorithm demonstrates the performance improvement over known studies by utilizing unit time and spatial proximity. In addition, this paper conducts a performance evaluation to measure the improvement in algorithm efficiency and analyzes the results of the performance evaluation. When spatial data queries are conducted, according to our performance evaluation, hit rate has been improved over the existing algorithms.

• Spatial Information Research
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• v.12 no.4 s.31
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• pp.321-328
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• 2004

The purpose of this study is to describe 3-Dimensional technique to obtain spatial information automatically using PhotoModeler Pro. PhotoModeler Pro is excellent software with the three-dimensional measurement function used by a personal computer using Windows operating system However, it is not sufficient to carry out the automatic matching work with two stereo images. This is very large neck as a 3-D measurement software. In this study, the automatic stereo matching work using the self-making program and DDE interface within PhotoModeler Pro was tried. The experiment field is the hillside and stair zone of Tateyama region, Nagasaki City. The results of automatic stereo matching work were very good with $100\%$ hitting ratio of target.

• The Journal of the Convergence on Culture Technology
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• v.6 no.2
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• pp.25-31
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• 2020

We aimed to investigate the moderating effect of kindergarten teachers' resilience in the relation between job stress and psychological burnout. The subjects were 164 early childhood teachers in Metropolitan area, South Korea. We measured subjects' job stress, psychological burnout, and resilience using the questionnaires. The collected data were analyzed with descriptive statistics, Pearson correlation analyses, and the analyses of hierarchical regression using SPSS 21.0. As results, kindergarten teachers' job stress showed the significantly positive correlation with their psychological burnout, but resilience showed the significantly negative correlation with it. It was found that kindergarten teachers' resilience had the moderating effect in the relation between job stress and psychological burnout.

• Korean Journal of Ichthyology
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• v.20 no.4
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• pp.279-284
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• 2008

The feeding ecology of endangered Cottus hangiongensis was studied in the Hosan stream from September 2006 to August 2007 by collecting them seasonally. The stomach contents of C. hangiongensis consisted mainly of aquatic insects and Nematoda, small fish, fish eggs, snails (Semisulcospira libertina), and small stones were also observed. The main aquatic insects in the order of relative importance were Diptera, Trichoptera, Ephemeroptera and Plecoptera. The most important prey items were Chironomidae sp.1 and Hydropsyche kozhantschikovi. Change in the main prey organisms by season were Trichoptera in the spring and the summer, Diptera in the autumn, and Plecoptera in the winter by ratio of dry weight.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.6
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• pp.129-134
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• 2015

This paper analyzes file access characteristics of smartphone apps and finds that a large portion of file writes are performed only once. Based on this observation, we present a new buffer cache management scheme that considers this characteristics. Buffer cache improves storage performance by maintaining hot file data in memory thereby servicing subsequent requests without storage accesses. However, it should flush modified data to storage in order to resist system crashes. The proposed scheme evicts cache data that has been written only once upon flushes, thus improving cache space utilization. Simulation experiments show that the proposed scheme improves cache hit ratio by 5-33% and power consumption by 27-92%.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.1
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• pp.71-78
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• 2016

This paper proposes the new electric power demand forecast model which is based on an artificial neural network and considers time and weather factors. Time factors are selected by measuring the autocorrelation coefficients of load demand in summer and winter seasons. Weather factors are selected by using Pearson correlation coefficient The important weather factors are temperature and dew point because the correlation coefficients between these factors and load demand are much higher than those of the other factors such as humidities, air pressures and wind speeds. The experimental results show that the proposed model using time and seasonal weather factors improves the load demand forecasts to a great extent.

• Journal of KIISE:Computer Systems and Theory
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• v.34 no.4
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• pp.138-144
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• 2007

With recent proliferation of video-on-demand services, caching in a multimedia streaming server is becoming increasingly important. Previous studies have shown that request interval based caching and its extension for considering different video popularity performs well in various streaming environments. In this paper, we show that block level refinement of this existing scheme can further improve the performance of streaming servers. Trace driven simulations with real world VOD traces have shown that the proposed scheme improves the cache hit rate and the startup latency.

• Journal of Korea Multimedia Society
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• v.5 no.1
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• pp.47-56
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• 2002

Previous buffer cache schemes for multimedia storage systems only exploited the sequential references of multimedia files and didn't consider looping references. However, in some video applications like foreign language learning, users mark the scene as loop area and then application automatically playbacks the scene several times. In this paper, we propose a new buffer replacement scheme, called HBM(Hybrid Buffer Management), for multimedia storage systems that have both sequential and looping references. Proposed scheme assumes that application layer informs reference pattern of files to file system. Then HBM applies an appropriate replacement policy to each file. Our simulation experiments show that HBM outperforms previous buffer cache schemes such as DISTANCE and LRU.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.367-367
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• 2019

최근 기후변화로 인해 국지성 호우 및 태풍의 빈도가 빈발하고 및 규모가 커지고 있으며 그로 인한 홍수피해규모는 증가하고 있다. 본 논문에서는 도시 지역의 호우로 인한 침수유발 강우량을 산정하는 기법의 정확도를 산정하는데 목적이 있으며 이를 위해 ROC(Receiver Operation Characteristic Curve) 분석을 이용하였다. 본 논문에서는 분포형 홍수해석 모형인 S-RAT 모형과 2차원 침수해석 모형 FLO-2D을 커플링하여 호우로 인한 침수해석을 실시하였으며 강우시나리오는 설계 강우 200mm의 강우를 10% 간격으로 증가시켜 강우량 대비 침수심 자료를 모의하였다. 모의한 침수심 자료를 이용하여 유역 격자를 $1km{\times}1km$ 별 강우량-침수심 관계곡선식을 제시하였으며 개발된 곡선식을 이용하여 특정 침수심(20cm)을 유발시키는 강우량(한계강우량)을 산정하였다. 정확도 산정은 ROC(Receiver Operation Characteristic Curve) 분석 방법을 이용하여 침수 유무의 적중률에 따른 민감도와 특이도를 이용하여 AUC(Area Under the Curve)의 점수로 정확도를 판단하였다. 본 논문에서는 본 논문에서 제시한 한계강우량의 정확도를 판단하기 위하여 2011년 7월의 사당역 일대 침수사례를 이용하였다. 실제 침수정보가 없어 실제 호우사상과 실제 하수관망을 고려할 수 있는 SWMM 모형을 이용하여 침수분석을 실시하였다. 분석 결과 평균 ROC는 약 0.7로 나타났으며 5 단계의 구분에서 Fair 단계로 적정 수준의 정확도를 확보한 것으로 나타났다.