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朴炳柱(Byoungju Park),李漢相(Hansang Lee),張吉洙(Gilsoo Jang) 대한전기학회 2006 전기학회논문지A Vol.55 No.1
The interest for harmonic problems has been increasing due to the increment of nonlinear loads. The loads such as DC power system, personal computers, UPS system, inverters and converters operate as harmonic current sources. In this paper, a new type of the passive filter, Hybrid Harmonic Filter (HHF) is suggested to mitigate harmonic problems in power systems. The HHF is developed for reducing harmonic current, especially on the system that includes 6-pulse bridge rectifiers. Also, it is expected to prevent the overheating of transformers and feeders due to overcurrent and to correct the power factor.
장승호(Seungho Jang),고효인(Hyoin Koh),박병주(Byoungju Park) 한국철도학회 2013 한국철도학회 학술발표대회논문집 Vol.2013 No.5
철도소음으로 인한 환경공해 문제를 예방하고 대책을 수립하기 위해서는 정확한 소음 예측 모델이 필요하다. 국내에서는 총합 소음도의 거리별 경험식에 기초한 철도소음 예측모델이 이용되고 있으나 다소 많은 오차를 내고 있어 개선이 요구된다. 본 논문에서는 소음원의 옥타브 밴드 주파수별 음향 파워와 지형 특성을 고려한 소음 전파 모델을 이용한 철도소음 예측모델을 제안하였다. 본 예측모델은 높이별로 위치한 소음원 음향 파워와 속도 계수, 궤도 및 교량 조건에 따른 보정값으로 구성되었다. 본 모델과 기존 모델로 예측한 속도별 소음도를 비교하였다. In order to solve the problem due to the railway noise, an accurate noise prediction model is required. Domestic prediction model based on the overall sound pressure level has resulted in relatively large errors. In this paper, a noise prediction model considering the octave band source powers and the various ground effects has been proposed. In the model the sources are presumed as being located at different heights and the speed parameters, correction values for the track and bridge condition are utilized. The noise levels at different running speeds predicted by the present model are compared with the existing model.
장승호(Seungho Jang),장은혜(Eunhae Jang),손정곤(Jung Gon Son),박병주(Byoungju Park) 한국소음진동공학회 2013 한국소음진동공학회 학술대회논문집 Vol.2013 No.10
An accurate railway environmental noise prediction model is required to make the proper solution of the railway noise problems. In this paper, an engineering model for predicting the noise of conventional passenger cars is presented considering the acoustic source strength in octave-band frequencies and the propagation over grounds with varying surface properties. Since the formation of a train can be variable, the source strength of each locomotive and passenger car was estimated by measuring the pass-by noise and analysing the wheel-rail rolling noise. Some validation cases show on the average small differences between the predictions of the present model and the measurement results.