• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.12
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• pp.6081-6088
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• 2012

An unequal clustering method in wireless sensor networks is the technique that forms the cluster of different size. This method decreases whole energy consumption by solving the hot spot problem. In this paper, I propose a layer-based dynamic unequal clustering using the unequal clustering model. This method decreases whole energy consumption and maintain that equally using optimal cluster's number and cluster head position. I also show that proposed method is better than previous clustering method at the point of network lifetime.

• Food Industry
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• s.15
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• pp.47-50
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• 1973

정부의 식생활개선정책에 발맞추어 우리들의 식생활구조는 점차 쌀위주의 고정관념에서 잡곡의 혼식, 분식의 패턴으로 현저한 변화를 가져여오고 유다. 그러나 식량소비패턴은 량과 질의 두가지 면에서 결정되어야 할 것이며, 현재의 식생활구조는 량과 질의 불균형한 소비 패턴을 보여주고 있다.

• Journal of Intelligence and Information Systems
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• v.28 no.4
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• pp.157-177
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• 2022

Investors are trading stocks by keeping a close watch on the order information submitted by domestic and foreign investors in real time through Limit Order Book information, so-called price current provided by securities firms. Will order information released in the Limit Order Book be useful in stock price prediction? This study analyzes whether it is significant as a predictor of future stock price up or down when order imbalances appear as investors' buying and selling orders are concentrated to one side during intra-day trading time. Using classification algorithms, this study improved the prediction accuracy of the order imbalance information on the short-term price up and down trend, that is the closing price up and down of the day. Day trading strategies are proposed using the predicted price trends of the classification algorithms and the trading performances are analyzed through empirical analysis. The 5-minute KOSPI200 Index Futures data were analyzed for 4,564 days from January 19, 2004 to June 30, 2022. The results of the empirical analysis are as follows. First, order imbalance information has a significant impact on the current stock prices. Second, the order imbalance information observed in the early morning has a significant forecasting power on the price trends from the early morning to the market closing time. Third, the Support Vector Machines algorithm showed the highest prediction accuracy on the day's closing price trends using the order imbalance information at 54.1%. Fourth, the order imbalance information measured at an early time of day had higher prediction accuracy than the order imbalance information measured at a later time of day. Fifth, the trading performances of the day trading strategies using the prediction results of the classification algorithms on the price up and down trends were higher than that of the benchmark trading strategy. Sixth, except for the K-Nearest Neighbor algorithm, all investment performances using the classification algorithms showed average higher total profits than that of the benchmark strategy. Seventh, the trading performances using the predictive results of the Logical Regression, Random Forest, Support Vector Machines, and XGBoost algorithms showed higher results than the benchmark strategy in the Sharpe Ratio, which evaluates both profitability and risk. This study has an academic difference from existing studies in that it documented the economic value of the total buy & sell order volume information among the Limit Order Book information. The empirical results of this study are also valuable to the market participants from a trading perspective. In future studies, it is necessary to improve the performance of the trading strategy using more accurate price prediction results by expanding to deep learning models which are actively being studied for predicting stock prices recently.

• Journal of the Korea Society of Computer and Information
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• v.12 no.3
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• pp.51-58
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• 2007

The shared-nothing multiprocessor architecture has advantages in scalability, this architecture has been adopted in many multiprocessor database system. But, if the data are not uniformly distributed across the processors, load will be unbalanced. Therefore, the whole system performance will deteriorate. This is the data skew problem, which usually occurs in processing parallel hash join. Balancing the load before performing join will resolve this problem efficiently and the whole system performance can be improved. In this paper, we will present an algorithm using merit of very large memory to reduce disk access overhead in performing load balancing and to efficiently solve the data skew problem. Also, we will present analytical model of our new algorithm and present the result of some performance study we made comparing our algorithm with the other algorithms in handling data skew.

• Journal of the Korean Association of Geographic Information Studies
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• v.15 no.2
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• pp.126-138
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• 2012

The purpose of this study is to evaluate the imbalance of green space using various spatial analysis methods and to establish the management zone for green space with service supply in the aspect of its use in Daegu. The total green space of Daegu is 48,936.1ha which is the second among 7 metropolitan cities of Korea. According to the imbalance analysis of green space, the Gini's coefficient based on the area was not high, on the other hand, the Gini's coefficient based on the population was high by above 0.6. According to an evaluation of service supply of green space in Dalseo-gu, the area within about 100m around large green space was supplied with green spaces of above $25m^2$/pop. On the other hand, the area such as Sangin, Jukjeon, and Yongsan was not almost supplied with green space. Finally, 'Rich zone', 'Fair zone', 'Poor zone', and Broken zone' could be established based on the service supply for the management direction of green space. The findings from this study can be used as the basic data for selecting the construction priority of new green spaces.

• Proceedings of the KIEE Conference
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• 2003.11a
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• pp.358-360
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• 2003

원자력과 같은 대용량 발전기의 갑작스런 탈락이나 하루 중 아침시간이나 점심시간과 같이 급격한 부하변동이 발생하는 특수 시간대에는 계통의 발전량과 부하량간에 심한 불균형이 발생하게 된다. 이 경우 계통 주파수가 변하여 발전량과 부하량이 자동으로 조절되어 수급의 균형이 이루어지게 되므로 계통이 안정하게 유지된다. 본 논문에서는 실계통 사고사례를 통하여 우리나라 계통에서 대용량 발전기 탈락시 주파수변동에 따른 발전량 및 부하량의 조절특성과 고장당시 계통 발전기들의 응동특성을 소개한다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.11
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• pp.861-871
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• 2020

Raising the speed of the momentum wheel in the CMG increases the unintended force and torque caused by mass imbalance. This unintended force and torque should be minimized to get the better quality of satellite SAR image because they lead to the vibration of the output image. This paper shows the works on compensating the static imbalance and couple mass imbalance in the CMG wheel. First, the force and torque at the center of mass generated by the mass imbalance were predicted through M&S analysis. Second, the force and torque were estimated similarly through the M&S analysis when the measurement point was moved from the rotation center. Third, the measurement configuration for the force and torque by the mass imbalance was described. Fourth, the change of the force and torque by adding the specified mass to the momentum wheel was observed after comparing the measurements with the results of the M&S. And finally, the effect of the compensation was analyzed by comparing the force and torque before and after the correction while 24Nm class CMG was running in the standby mode.

• Journal of Nutrition and Health
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• v.36 no.9
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• pp.898-907
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• 2003

Antioxidative function of uncooked powdered food (Sangsik) was evaluated in rats consuming nutritionally unbalanced diet including 1％ cholesterol, high proportion of animal lipids (lard : soybean oil : 8 . 2) , sub-optimal levels of vitamin and mineral mixture along with 0.5% ethanol in drinking water. The uncooked powdered food tested in the present study was a mixture composed of 42 kinds of plant foods (cereals, legumes, seaweeds, vegetables, and fruits) supplemented with vitamins and minerals, and dietary fiber. Control rats were fed the semi-purified diet based on the AIN-93G composition, and nutritionally unbalanced rats were divided into 3 groups, and fed one of the following diets with 0.5% ethanol in drinking water for 5 weeks : unbalanced control diet (UC) ,20% Sangsik powder supplemented diet (S20), and 40% Sangsik powder supplemented diet (S40) . Food efficiency ratio was significantly higher in rats fed S40 compared to the value for rats fed UC (p < 0.05). Hepatic level of thiobarbituric acid reactive substances (TBARS) was significantly lower in rats fed UC compared to that for control rats (p < 0.05) , and was not influenced by dietary supplementation of the Sangsik powder. Hepatic superoxide dismutase (SOD) activity was significantly higher in rats fed UC compared to that for control rats (p < 0.05) , and significantly reduced in rats fed S20 or S40 compared to the value for unbalanced control rats. Feeding unbalanced control diet significantly reduced the ratio of hepatic GSH-Px ＋ catalase/SOD activities compared to the value for control rats, and this decrease in the ratio of antioxidant enzyme activities was reversed by adding the Sangsik powder to the diet at 20% (p <0.05) . Based on the results of antioxidant enzyme activities, feeding uncooked powdered diet appears to provide a favorable environment for body's antioxidative defense mechanism. Serum levels of Fe and Cu were significantly lower in rats fed the Sangsik powder supplemented diets compared to the value for unbalanced control rats (p < 0.05) , and levels of Se, Mn, and Zn were also tended to be decreased by dietary supplementation of the Sangsik powder. These results postulate the possibility that ingredients used in the uncooked powdered food may decrease the bioavailability of trace elements in rats.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1998.04a
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• pp.194-199
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• 1998

축어긋남이 있는 회전체-볼베어링계에 대한 동적모델을 이용하여, 각축어긋남에 의한 2x 축진동현상을 조사하였다. 이때 유효베어링강성계수를 정의하여 축어긋남과 불균형량에 의해 발생되는 강성계수의 평균과 동기 변화성분을 운동방정식에 도입하였다. 수치해석과 실험결과는 각축어긋남에 의한 바나나 형태의 선회궤적이 회전체계 임계속도의 1/2이 도는 속도영역에서 뚜렷이 나타나는 것을 보여주었다.

• Journal of the Korean Data and Information Science Society
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• v.4
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• pp.121-130
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• 1993

For the One-way random effects model with unbalanced data, the AOV and MINQUE estimates of variance components are frequently found to be negative. The primary objective of present study is placed on the computation of the probability of the main effect variance component, being negative. The probability of negative estimators from AOV and MINQUE can be obtained by theoretical computation under the normality assumption. It is, however, difficult to compute the probability of negative estimates for these estimators under arbitrary distributions, and hence their probabilities of being negative were computed by simulation experiment in this study. It was shown that there was no significant difference between the theoretical probability under normality and calculated probability by simulation experiment, and that probability of negative estimates decreases as sample size, number of levels and the value of increase.