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이창선,김용진,김상수,Lee, Chang-Sun,Kim, Yong-Jin,Kim, Sang-Sao 대한기계학회 2000 大韓機械學會論文集B Vol.24 No.6
Photoelectric charging is a very efficient way of charging small particles. This method can be applied to combustion measurement, electrostatic precipitator, metal separation and control of micro-contamination. To understand the photoelectric charging mechanism, particle charging of silver by exposure to ultraviolet is investigated in this study. Average charges and charge distributions are measured at various conditions, using two differential mobility analyzers, a condensation nucleus counter, and an aerosol electrometer. The silver particles are generated in a spark discharge aerosol generator. After that process, the generated particles are charged in the photoelectric charger using low-pressure mercury lamp that emits ultraviolet having wavelength 253.7 nm. The results show that ultra-fine particles are highly charged by the photoelectric charging. The average charges linearly increase with increasing particle size and the charge distribution change with particle size. These results are discussed by comparison with previous experiments and proposed equations. It is assumed that the coefficient of electron emission probability is affected by initial charge. The results also show that the charge distribution of a particle is dependent on initial charge. Single changed particle, uncharged particle and neutralized particle are compared. The differences of charge distribution in each case increase with increasing particle size.
이창선,강희모,심송용,Lee, Chang-Sun,Kang, Hee-Mo,Sim, Song-Yong 한국데이터정보과학회 2012 한국데이터정보과학회지 Vol.23 No.1
많은 조사에서 표본 크기는 유의수준 또는 제1종 오류확률만을 고려하여 결정하였으나 최근에는 다양한 분야를 중심으로 제1종 오류확률뿐만 아니라 제2종 오류확률 또는 검정력을 함께 고려하여 표본 크기를 결정하는 경우가 늘어나고 있다. 이런 경향은 표본을 많이 얻을 수 없는 연구에서 더욱 뚜렸하다. 본 연구에서는 모평균과 모비율에 대한 검정에서 제1종 오류뿐만 아닌 제2종 오류를 고려한 경우 필요한 표본 크기를 결정하는 과정을 살펴보고 이를 웹사이트를 통해 공개하였다. 또한 주어진 표본 크기와 유의수준에 의한 검정력 계산도 함께 공개하였다. There are cases when the sample size is determined based not only on the significance level but also on on the power or type II error. In this paper, we implemented the sample size and the power calculation when both the significance level and power for testing means in normal distributions and proportions in binomial distributions. The implementation is available on a web site. Alternately, we also calculate the power for a given effect size, type I error probability and sample size.
대전된 입자의 영상효과에 의한 필터효율 향상에 관한 실험적 연구
이창선,정해영,김상수,Lee, Chang-Sun,Jeong, Hae-Young,Kim, Sang-Soo 대한기계학회 2000 大韓機械學會論文集B Vol.24 No.6
Filter efficiency of electrically charged particle in uncharged fibrous filter was measured. In previous studies, the effect of charged particle on filter efficiency was investigated but there was difficulty in measuring of image effect that is appeared at the charged small particle. We could easily measure the image effect with charging small particles by photoelectric charging. The spark discharge aerosol generator and a differential mobility analyzer (DMA) were used to generate sub-micron monodisperse particles (${\leq}200$ nm). The generated particles were charged in photoelectric charging process using ultraviolet lamp and electric field. The filter efficiency of the charged particles, classified by another DMA, was measured in filter tester using a condensation nucleus counter (CNC) as function of particle diameter, particle charge and airflow velocity. It is shown that the filter efficiency increases with increasing charge number of the particle and is affected by particle size and flow velocity. Single fiber filter efficiency mainly depends on image force parameter and peclet number. The peclet number was not considered at previous other papers. We propose a modi fied experimental correlation as function of image force parameter and peclet number.
GIS와 통계분석기법을 활용한 제주지역 급경사지재해 예측 및 평가
이창선(Lee Chang Sun),이병걸(Lee Byung Gul),권혁춘(Quan He Chun),고정우(Ko Jung Woo) 대한공간정보학회 2010 한국공간정보학회 학술대회 Vol.2010 No.1
본 연구에서는 급경사지재해 발생구간에 따른 토질특성을 분석하고 통계적분석을 GIS 기법에 적용하여 급경사지재해를 예측해 보고자 하였다. 이를 위하여 사람의 발길이 많은 사라봉, 별도봉 지역과 송악산 지역의 지형 및 토질공학적 사면 붕괴 유발 인자들을 이용하여 로지스틱회귀분석기법을 GIS에 적용한 예측지도를 작성하고 급경사지재해지역을 예측 및 평가해 보고자 하였다.
이창선 ( Lee Chang-sun ),최현호 ( Choi Hyun-ho ),오홍섭 ( Oh Hong-sub ),조효남 ( Cho Hyo-nam ) 한국구조물진단유지관리공학회 2007 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.11 No.1
In this paper, Annual Frequency of collapse(AP) of bridge pier is estimated through the realistic material modeling and structural modeling based on the description of applied bridge. An analysis of AF is carried out as following the AASHTO Guide Specification(1991) then, barge and small ship collision analysis using detail finite element analysis is carried out with respect to longitudinal and lateral impact assessment in order to verify the safety of bridge pier. Also, reliability index according to estimated failure probability is calculated.