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반응고 주조공정에서 평면도 증대를 위한 공정변수의 최적설계
김현구(Hyungoo Kim),정성종(Sung-Chong Chung) 한국생산제조학회 2008 한국생산제조학회지 Vol.17 No.6
Mg alloy is widely used for the IT, auto and consumer electronics industries. Semi-solid casting(SSC) of magnesium alloys is used to produce high quality components. SSC process is analogous with the injection molding of plastics. The high strength and low weight characteristics of magnesium alloys render the high-precision fabrication of thin-walled components with large surface areas. To produce thin-walled magnesium alloy parts, SSC process parameters on the quality of the finished product should be clearly studied. In this paper, to select optimal process parameters, Taguchi method is applied to the optimal design of the process parameters in the SSC process. The die temperature, injection velocity and barrel temperature of the SSC process are selected for the process parameters. The effectiveness of the optimal design is verified through the CAE software.
한반도 바람지도 구축에 관한 연구 (I. 원격탐사자료에 의한 종관 바람지도 구축)
김현구(Kim, Hyungoo),최재우(Choi, Jaeou),이화운(Lee, Hwawoon),정우식(Jung, Woosik) 한국신재생에너지학회 2005 신재생에너지 Vol.1 No.1
To understand general status of the national wind environment and to distinguish potential areas to be developed as a largescale wind farm, a synoptic wind map of the Korean Peninsula is established by processing remote sensing data of the satellite, NASA QuikSCAT which Is deployed for the SeaWinds Project since 1999. According to the validation results obtained by comparing with the measurement data of marine buoys of KMA(Korea Meteorological Administration), the cross-correlation factor Is greatly Improved up to 0.87 by blending the sea-surface dat3 of QuikSCAT with NCEP/NCAR CDAS data. It is found from the established synoptic wind map that the wind speed in winter is prominent temporally and the South Sea shows high energy density up to the wind class 6 spatially. The reason is deduced that the northwest winds through the yellow Sea and the northeast winds through the East Sea derived by the low-pressure developed in Japan are accelerated passing through the Korea Channel and formed high wind energy region in the South Sea; the same trends are confirmed by the statistical analysis of meteorological observation data of KMA.
ARIMA와 SARIMA 시계열 분석기법을 이용한 대전지역 초단시간 일사량 선행예보모델 구축
김동희(Kim DongHee),김유정(Kim YooJung),김창기(Kim ChangKi),김현구(Kim HyunGoo),이영섭(Lee YungSeop) 한국태양에너지학회 2022 한국태양에너지학회 논문집 Vol.42 No.6
Solar irradiance is a major meteorological factor affecting solar energy generation. In this study, we develop a short-term solar irradiance forecasting model with a high time resolution to accurately predict the amount of solar energy generated and apply it to the real-time energy trade market. Two types of irradiance (Global Horizontal Irradiance and Direct Normal Irradiance) data observed at Daejeon, South Korea, are predicted using two time series analysis models (the ARIMA model, which does not consider seasonality, and SARIMA model which considers seasonality), which we compared to determine the model that is better suited to performing predictions. Comparing the prediction errors from 15 to 120 minutes, using RMSE and nRMSE as evaluation indices, GHI was better predicted using the ARIMA model from 15 to 75 minutes, while the SARIMA model performed better from 90 to 120 minutes. For DNI, the ARIMA model showed higher accuracy than the SARIMA model during the entire prediction period.