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鄭泰旭,李泰煥 진주산업대학교 1999 산업과학기술연구소보 Vol.- No.6
Recently, a Switched Reluctance Motor(SRM) is researched on improvement of control scheme, optimization of magnetic structure, combination of motor and inverter, and reduction of torque ripple vibration, acoustic noise and vibration. Especially, one of the disadvantage of an SRM is the higher torque ripple compared with conventional drive system. In this viewpoint, Fully-pitch SRM has many versatilities, and acoustic noise and torque ripple can be reduced by optimal design of magnetic structure and proper switching controls. Fully-pitch SRM adopts the fully-pitch winding method and develops torque by mutual inductance and self inductance. In order to design motor structure, estimation of inductance and prediction of torque characteristics are indispensable. So this paper suggests the estimation method of inductance using permeance calculation method, and design appropriate magnetic structure which can be reduced torque ripple by using this method.
정태환 고려대학교 한국학연구소 2002 한국학연구 Vol.17 No.-
Since the liberation, Korea has experienced chronic socio-political conflict, and has been significantly influenced by foreign countries. Major issues raised by socio-political conflict events are right wing dictatorship economic problems, and political corruption. While the issues point to the immediate problems responsible for the conflict, an attempt is made to clarify how the issues mediate and influence Korean politics. Government performance in response to the issues seem to be the most important intervening variable in Korean political instability. Socio-political conflict has started out by mass effort to supplement the inadequacy of the exercise of government, to supplant legitimate ruling elites, and reorganize the existing socio-political order.
Ogive-Cylinder 형 첨두부를 갖는 유도무기 주위 고앙각 흐름에서의 비대칭 와류 특성과 이에 따른 측력발생에 대한 수치적 해석 연구
정성기,제상언,명노신,조태환 慶尙大學校 經營行政大學院 2004 工學硏究院論文集 Vol.20 No.-
The demand for continually increased performance of missiles and aircraft leads to considering flight at very high angle of attack where control is very difficult. This is mainly due to shedding of asymmetric vortices from the forebody, producing side forces even at zero sideslip. In this paper, Computational Fluid Dynamics(CFD) was used to analyze characteristic of asymmetric vortices and examine the effects of several cases for rising asymmetric vortices. There are asymmetric grid cluster, sideslip angle and roughness. As a result of the study, asymmetric vortices were sensitive at the areas of roughness and the analysis results coincided with the experiment results at the specified area.
콩 단백질/펙틴/몬모릴로나이트 나노복합 필름의 특성 및 산소 투과도 연구
정세환,김성철,조규순,신용섭,장상희,홍기헌,이태진,신부영 嶺南大學校 工業技術硏究所 2004 工業技術硏究所論文集 Vol.32 No.2
In this study, Mechanical property, thermal property, watervapor, and oxygen permeability of biodegradable Soy protein/Pectin-montmorillonite nanocomposite, prepared with Na^(+)-MMT, have been studied. X-ray diffraction and TEM experiments an polymer/silicate composite samples demonstrated that the intercalation of polymer chains leads to increase in the spacing between silicate layers. In addition, it were found that the intercalated Soy protein/Pectin/montmorillonite nanocomposite were prepared. It was found that the addition of only a small of clay was enough to improve the thermal stability and mechanical property of Soy protein/Pectin/montmorillonite nanocomposite. watervapor of Soy protein/Pectin/montmorillonite nanocomposite was generally lower than that of Soy protein/Pectin. oxygen permeability of Soy protein/Pectin/montmorillonite nanocomposite was generally lower than that of Soy protein/Pectin.
국내 하천 퇴적물 건강성평가를 위한 Microtox 독성시험 조건확립 연구
정홍배,박정규,문성환,류태권,김소정,배철한,황인영 한국환경독성학회 2001 환경독성보건학회지 Vol.16 No.4
1. 하천 퇴적물 공극수, 증류수 추출용액 및 유기용매 추출액을 pH6.0~6.5 범위로 조절한 후 Microtox 독성을 측정하는 것이 퇴적물내의 암모니아 독성이 배제된, 유해화학물질 오염에 의한 퇴적물 독성을 평가하는 방안임을 확인하였다. 2. 퇴적물에 대해 공극수, 증류수 추출물, 유기용매 추출물 구분하여 Microtox 독성을 구하는 것이 퇴적물 내 유해화학물질의 독성발현 특성을 예측할 수 있는 기법이라고 사료된다. 3. 조사정점 내 시료 채취 지점간 독성에 편차로 인하여, 동일 정점의 반경 50~100m 내에서 최소 4지점 이상의 퇴적물을 확보하는 것이 해당 정점의 독성 대표값을 산출할 수 있는 방안이 된다고 판단된다. 4. 한강수계인 남한강 지천인 복하천과 양화천, 금강수계인 청주 미호천, 대전 갑천, 낙동강수계인 대구 금호강, 영산강수계인 황룡강 그리고 익산 만경강을 대상으로 한 예비 조사한 결과, 집중연구대상 하천으로의 조건은 금호강이 가장 우수하였다. 5. 하천 퇴적물의 증류수 추출액과 유기용매 추출액의 Microtox 독성값 간의 상호 상관성이 높았다. 그러나, 농축 과정이 용이하므로 정점간 비교를 위한 독성 측정시 유기용매 추출액을 사용하는 것이 바람직하다고 사료되었다. Six rivers were selected as preliminary screening sites to determine the test conditions of Microtox in assessing the toxicity of the sediment. In addition, a pH range of 6.0--6.5 was established in testing pore water, aqueous extracts and organic extracts. Each extractable fraction of sediment showed different toxicities. Therefore, in order to properly examine the toxicity in the sediment, all extractable fractions of sediment samples needed to be tested with Microtox. Thus, sediment samples were additionally collected from at least 4 secondary sites within 50~100 m area of the primary sampling site to reduce any variation or deviation in toxicity assessment. From all sediment toxicity data that was collected from this study, it was concluded that the Keumho river was the most polluted with the highest sediment toxicity of all the rivers analyzed and needed further detailed research on its pollution problem.
Switched Reluctance Motor의 진동, 소음 특성해석에 관한 연구
정태욱,최태완,이태환 진주산업대학교 2000 산업과학기술연구소보 Vol.- No.7
Switched reluctance motor(SRM) drive system is to be compatible for wide range adjustable speed motoring system because it has the same driving characteristics of DC series motor, easy control principle and high efficiency characteristics. By this reason, SRM drive system will be applied to many commercial adjustable speed application that requires economic advantages and high performance abilities. But, SRM drives generate large vibration and acoustic noise because it is rotated by step pulse mmf and switching commutation mechanism. This disadvantage has been obstacles to applicate SRM drives as generalized motor drive system. The main origin of vibration and noise is caused by commutation method which applies step pulse waveform mmf to stator pole and removes the mmf suddenly. This sudden variation of stator flux vibrates stator frame by radial direction and excites natural vibration mode of stator. This paper analyzes the characteristics of vibration and acoustics noise of SRM from the viewpoint of natural mode and driving coidition, and consider the reduction strategy of that.