• 한국환경과학회지
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• 제26권2호
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• pp.221-230
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• 2017

To determine the effect of air pollution reduction policies, the long-term trend of air pollutants should be analyzed. Kolmogorov-Zurbenko (KZ) filter is a low-pass filter, produced through repeated iterations of a moving average to separate each variable into its temporal components. The moving average for a KZ(m, p) filter is calculated by a filter with window length m and p iterations. The output of the first pass subsequently becomes the input for the next pass. Adjusting the window length and the number of iterations makes it possible to control the filtering of different scales of motion. To break down the daily mean $PM_{10}$ into individual time components, we assume that the original time series comprises of a long-term trend, seasonal variation, and a short-term component. The short-term component is attributable to weather and short-term fluctuations in precursor emissions, while the seasonal component is a result of changes in the solar angle. The long-term trend results from changes in overall emissions, pollutant transport, climate, policy and/or economics. The long-term trend of the daily mean $PM_{10}$ decreased sharply from $59.6ug/m^3$ in 2002 to $44.6ug/m^3$ in 2015. This suggests that there was a long-term downward trend since 2005. The difference between the unadjusted and meteorologically adjusted long-term $PM_{10}$ is small. Therefore, we can conclude that $PM_{10}$ is unaffected by the meteorological variables (total insolation, daily mean temperature, daily mean relative humidity, daily mean wind speed, and daily mean local atmospheric pressure) in Busan.

• 대한전기학회논문지
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• 제41권9호
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• pp.994-1002
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• 1992

With regard to price elasticity and cross elasticity of electricity, optimal generation expansion planning method including load management effect is suggested. In addition, optimal peak time price can be determined simultaneously, and we adopt peak time tariff as load management strategy. Instead of using hourly marginal demand curves where we can get customer surplus, we used chronological load curve with constraints to preserve social welfare. This method is proved useful in short-term generation expansion planning.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 D
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• pp.1177-1179
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• 1997

In this paper, short-term power demand forecast using exclusion of week periodicity presented. Week periodicity excluded from weekday change ratio. Forecast term of five and multiple regression model of the three form was composed. Forecast result was good. Therefore, It Could be the power demand forecast of special day(weekend). This method may contribute improvement of forecast accuracy.

• 전기학회논문지
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• 제62권4호
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• pp.482-488
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• 2013

Load forecasting is essential to the economical and the stable power system operations. In general, the forecasting days can be classified into weekdays, weekends, special days and special light-load periods in short-term load forecast. Special light-load periods are the consecutive holidays such as Lunar New Years holidays, Korean Thanksgiving holidays and summer special light-load period. For the weekdays and the weekends forecast, the conventional methods based on the statistics are mainly used and show excellent results for the most part. The forecast algorithms for special days yield good results also but its forecast error is relatively high than the results of the weekdays and the weekends forecast methods. For summer special light-load period, none of the previous studies have been performed ever before so if the conventional methods are applied to this period, forecasting errors of the conventional methods are considerably high. Therefore, short-term load forecast for summer special light-load period have mainly relied on the experience of power system operation experts. In this study, the trends of load profiles during summer special light-load period are classified into three patterns and new forecast algorithms for each pattern are suggested. The proposed method was tested with the last ten years' summer special light-load periods. The simulation results show the excellent average forecast error near 2%.

• Journal of Electrical Engineering and Technology
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• 제12권1호
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• pp.64-71
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• 2017

Considering the volatility, intermittent and random of photovoltaic (PV) generation systems, accurate forecasting of PV power output is important for the grid scheduling and energy management. In order to improve the accuracy of short-term power forecasting of PV systems, this paper proposes a prediction model based on environmental factors and support vector machine optimized by genetic algorithm (GA-SVM). In order to improve the prediction accuracy of this model, weather conditions are divided into three types, and the gray correlation coefficient algorithm is used to find out a similar day of the predicted day. To avoid parameters optimization into local optima, this paper uses genetic algorithm to optimize SVM parameters. Example verification shows that the prediction accuracy in three types of weather will remain at between 10% -15% and the short-term PV power forecasting model proposed is effective and promising.

• 상하수도학회지
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• 제26권6호
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• pp.907-914
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• 2012

Flexible pipes take advantage of their ability to move, or deflect, under loads without structural damage. Common types of flexible pipes are manufactured from polyethylene (PE), polyvinyl chloride (PVC), steel, glass fiber reinforced thermosetting polymer plastic (GFRP), and aluminum. In this paper, we present the result of an investigation pertaining to the short-term behavior of buried polyethylene pipe. The mechanical properties of the polyethylene pipe produced in the domestic manufacturer are determined and the results are reported in this paper. In addition, vertical ring deflection is measured by the laboratory model test and the finite element analysis (FEA) is also conducted to simulate the short-term behavior of polyethylene pipe buried underground. Based on results from soil-pipe interaction finite element analyses of polyethylene pipe is used to predict the vertical ring deflection and maximum bending strain of polyethylene pipe.

• 무역상무연구
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• 제69권
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• pp.427-451
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• 2016

With WTO system starting since 1995, the international trade business has been getting more competitive and fairer especially with the agreement on subsidies and countervailing measures. The export credit insurance, as the only institution of supporting export business under WTO system, is getting more significant in major economies as an indirect means to support export business. In China, SINOSURE has been monopolizing its export credit insurance market for a long time. Since January 2013, however, the Chinese government permitted several commercial insurers to compete in the market and they include PICC, PING AN, CPIC, China Re. This study is to discuss how to improve the Chinese export credit insurance after analyzing performance of privatization of short-term credit insurance and real cases of success and failures. With the 'Go Global' and 'One Belt, One Road' policy of Chinese government, the role of export credit insurance is expected to be more significant. Thanks to the Korea-China FTA since December 2015, international trade between the two countries will be greater especially in finance and insurance area. Because Korean insurance industry is very much interested in getting into Chinese export credit insurance market, they need to study carefully the performance of privatization of Chinese short-term export credit insurance. For their policy decision makings the Korean authorities need to get lessons from the privatization of Chinese short-term export credit insurance business.

• 한국통신학회논문지
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• 제18권3호
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• pp.348-354
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• 1993

본 논문에서는 음성의 short-term 계수 추출에 대한 새로운 방식을 제안하였으며, 데이타량 9.6Kbits/sec의 멀티 트리 부호기를 실현하였다. 이 트리 부호기는 총 지연시간 2.5msec을 (6.4KHz 샘플링 주파수에서 16샘플) 가지며, 좋은 출력 음질을 가지며, bit 오욜 (BER) $10^{-3}$에서도 견실한 상태를 유지한다. 이 견실성은 short-term 계수 추출을 위해 수신된 여기 신호를 smoothing 하여, 병렬 구성과 함께 사용하므로 가능 하였다. 이 부호기의 출력 음성은 SNR, SNRSEG, 그리고 듣기 시험으로 평가 되었다.

• 한국양식학회지
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• 제10권3호
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• pp.273-279
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• 1997

자주복(Takifugu rubripes) 정자의 액상보존을 위한 기초자료를 얻고자, 수조사육한 전장 43.5-45.1 cm, 체중 1.7-2.0 kg의 2-3년생 자주복 수컷을 재료로 하여, 정자의 액상보존 효과를 연구하였다. 희석액으로 marine fish ringer solution과 1% NaCl을 사용하여 7일간 보존하였을 때, SAI와 정자의 생존율이 각각 1.7과 $59.0\pm1.5%,\;1.6$과$\;56.7\pm6.2%$로 가장 높았다. 정자를 3-5배로 희석하여 보존하였을 때, 가장 높은 SAI와 정자의 생존율을 보였으며, 보존온도로는 0- 5$^{\circ}C$가 적절하였다. SAI와 정자의 생존율을 높이기 위한 항생제로는 neomycin (800 ppm)이 효과적이었다.

• Ocean and Polar Research
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• 제34권2호
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• pp.185-195
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• 2012

This paper focused on forecasting a short-term production of oysters, which have been farmed in Korea, with distinct periodicity of production by year, and different production level by month. To forecast a short-term oyster production, this paper uses monthly data (260 observations) from January 1990 to August 2011, and also adopts several econometrics methods, such as Multiple Regression Analysis Model (MRAM), Seasonal Autoregressive Integrated Moving Average (SARIMA) Model, and Vector Error Correction Model (VECM). As a result, first, the amount of short-term oyster production forecasted by the multiple regression analysis model was 1,337 ton with prediction error of 246 ton. Secondly, the amount of oyster production of the SARIMA I and II models was forecasted as 12,423 ton and 12,442 ton with prediction error of 11,404 ton and 11,423 ton, respectively. Thirdly, the amount of oyster production based on the VECM was estimated as 10,425 ton with prediction errors of 9,406 ton. In conclusion, based on Theil inequality coefficient criterion, short-term prediction of oyster by the VECM exhibited a better fit than ones by the SARIMA I and II models and Multiple Regression Analysis Model.