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엇갈린 격자를 이용한 3차원 유한차분 시간영역 전자탐사 모델링
장한길로,남명진,조성오,김희준,Jang, Hangilro,Nam, Myung Jin,Cho, Sung Oh,Kim, Hee Joon 한국지구물리물리탐사학회 2017 지구물리와 물리탐사 Vol.20 No.3
Interpretation of time-domain electromagnetic (TEM) data has been made mostly based on one-dimensional (1-D) inversion scheme in Korea. A proper interpretation of TEM data should employ 3-D TEM forward and inverse modeling algorithms. This study developed a 3-D TEM modeling algorithm using a finite difference time-domain (FDTD) method with staggered grid. In numerically solving Maxwell equations, fictitious displacement current is included based on an explicit FDTD method using a central difference approximation scheme. The developed modeling algorithm simulated a small-coil source configuration to be verified against analytic solutions for homogeneous half-space models. Further, TEM responses for a 3-D anomaly are modeled and analyzed. We expect that it will contribute greatly to the precise interpretation of TEM data. 국내에서 시간영역 전자탐사(time-domain/transient electromagnetic, TEM) 자료의 해석은 1차원 알고리듬에 주로 의존하고 있는 실정이기 때문에 정밀한 해석을 위하여 3차원 모델링 및 역산 해석 프로그램의 개발이 필요한 상황이다. 이 연구에서는 엇갈린 격자를 이용한 시간영역 유한차분(staggered-grid finite-difference time-domain, FDTD)법에 기초하여 3차원 TEM 반응 모델링 알고리듬을 개발하였다. 시간영역 전자탐사의 모델링을 위해 맥스웰 방정식을 현시적 중앙점 FDTD법을 이용하여 이산화하였으며 수치 안정성을 높이기 위해 가상 변위전류항을 도입하였다. 일반적으로 많이 활용되는 소형 코일 송신원을 수치적으로 구현하여 균질 반무한 공간에서의 해석해와 비교 검증하고 3차원 이상체에 대한 반응을 분석하였다. 이 연구에서 개발된 모델링 프로그램은 향후 TEM 전자탐사 자료의 정밀 해석에 기초가 될 것으로 기대한다.
김선규,허성환,조성오,Kim, Seon-Kyu,Heo, Sung-Hwan,Cho, Sung-Oh 한국진공학회 2005 Applied Science and Convergence Technology Vol.14 No.4
고휘도 마이크로빔 X-선원에 사용할 고휘도 전자빔원을 탄소나노튜브를 이용하여 설계, 제작하였다. 전자빔원은 탄소나노튜브 팁을 이용한 음극, 전자빔 인출용 그리드, 전자빔 가속용 양극으로 이루어진 삼극관 형태의 구조를 가진다. 설계된 휘도 값을 얻기 위하여 X-선 발생부에서의 전자빔 직경이 5 $\mu$m 이하, 빔전류가 약 30 $\mu$A 이상이 요구된다 이러한 요구조건을 만족시키기 위하여, EGUN Code를 이용하여 전자빔의 궤적 및 공간분포 등을 계산함으로써, 탄소나노튜브 팁 및 전자빔원의 구조 등을 최적화 하였다. 제작된 탄소나노튜브 팁은 직경 200 $\mu$m 의 텅스텐 와이어를 전기화학적으로 에칭하여 그 끝을 뽀족하게 만든 뒤 텅스텐의 끝 부분에 탄소나 노튜브를 화학기상법으로 증착하여 제작하였다. 제작된 탄소나노튜브를 이용하여 전자빔 인출실험을 수행하였다. 개발 중인 탄소나노튜브 팁을 이용한 고휘도 전자빔원의 설계 특성 및 기초 실험결과를 보고한다. A high-brightness electron beam source for a microfocus X-ray tube has been fabricated using a carbon-nanotube (CNT) field emitter. The electron source consists of cathode that includes a CNT field emitter, a beam-extracting grid, and an anode that accelerates that electron beam. The microfocus X-ray tube requires an electron beam with the diameter of less than 5 $\mu$m and beam current of higher than 30 $\mu$A at the position of the X-ray target. To satisfy the requirements, the geometries of the field emitter tips and the electrodes of the gun was optimized by calculating the electron trajectories and beam spatial profile with EGUN code. The CNT tips were fabricated with successive steps: a tungsten wire with the diameter of 200 $\mu$m was chemically etched and was subsequently coated with CNTs by chemical vapor deposition. The experiments of electron emission at the fabricated CNT tips were performed. The design characteristics and basic experimental results of the electron source are reported.
약국의 서비스 품질과 특성이 고객만족과 재이용 의도에 미치는 영향
이정승 ( Jung Seung Lee ),조성오 ( Sung Oh Cho ) 한국경영공학회 2011 한국경영공학회지 Vol.16 No.1
Although there is previous research that investigates service quality theory related to hospitality, telecommunication, and financial industries, little research focuses on the service quality and characteristics of the retail pharmacy industry. The objective of this study is to identify the factors on which influence customer satisfaction and intention to reuse by service quality and characteristics in the pharmacy industry. To do so, we analyzed service quality and characteristics in pharmacy and explored how they influence customer satisfaction and intention to reuse. We developed a structural model regarding the impact of customer satisfaction and intention to reuse toward pharmacy. Based on an experimental analysis and LISREL, we found that results of this study supported most our hypotheses in that service quality such as tangibles, reliability, responsiveness, diversity and characteristics such as fame directly influenced customer satisfaction and intention to reuse, and customer satisfaction to pharmacy directly influenced intention to reuse as results. Managerial implications were discusses on the basis of the results of this study.
김빛나래,유희은,조아현,송서영,조성오,정인석,남명진,Kim, Bitnarae,Caesary, Desy,Yu, Huieun,Cho, AHyun,Song, Seo Young,Cho, Sung Oh,Joung, Inseok,Nam, Myung Jin 한국지하수토양환경학회 2020 지하수토양환경 Vol.25 No.2
Analyzing and monitoring environmental contaminants based on geophysical exploration techniques have become important and it is now widely applied to delineate spatial distribution geophysical characteristics in wide area. Among the techniques, induced polarization (IP) method, which measures polarization effects on electrical potential distribution, has drawn much attention as an effective tool for environmental monitoring since IP is sensitive to changes in biochemical reactions. However, various reactions stemming from the presence of multiple contaminants have greatly enhanced heterogeneity of polluted sites to result in highly variable electrical characteristics of the site. Those contaminants influence chemical and physical state of soil and groundwater to alter electrical double layer, which in turn influences polarization of the media. Since biochemical reactions between microbes and contaminants result in various IP effects, IP laboratory experiments were conducted to investigate IP responses of the contaminated soil samples under various conditions. Field IP surveys can delineate the spatial distribution of contamination, while providing additional information about electrical properties of a target medium, together with DC resistivity. Reviewing IP effects of contaminants as well as IP surveys can serve as a good starting point for the application of IP survey in site assessment for environmental remediation.
전자빔 조사에 의한 방향성 전기강판의 철손 감소를 위한 소형 전자빔 조사장치 설계
김민(Min Kim),조경재(Kyeng-jai Cho),차인수(In-Su Cha),조성오(Sung-Oh Cho),이종민(jong-Min Lee) 전력전자학회 2000 전력전자학술대회 논문집 Vol.2000 No.11
A nonconstact technique for reducing the core loss of a grain oriented silicon steel has been developed by the use of mechanical scribing, Q-switched laser, plasma jet or electron beam irradiation.<br/> Among these methods electron beam irradiation has advantages of domain refining without any deformation or damage of insulating film on the surface of a grain oriented SI- Fe.<br/> Over the past years, this processing was performed in vaccum of 10-4 Torr or below causing the problem of high cost and difficulty of continuous works.<br/> In this paper, a miniature electron permeable window through which electron beam energy 40-80keV and average current 0.1-2mA were obtained for electron beam Irradiating on air was designed and manufactured