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전자빔 조사가 ZnO 박막의 전기적 특성 변화에 미치는 영향
최준혁,조인환,김찬중,전병혁,Choi, Jun Hyuk,Cho, In Hwan,Kim, Chan-Joong,Jun, Byung-Hyuk 한국전기전자재료학회 2017 전기전자재료학회논문지 Vol.30 No.1
The effect of low temperature ($250^{\circ}C$) heat treatment after electron irradiation (irradiation time = 30, 180, 300s) on the chemical bonding and electrical properties of ZnO thin films prepared using a sol-gel process were examined. XPS (X-ray photoelectron spectroscopy) analysis showed that the electron beam irradiation decreased the concentration of M-O bonding and increased the OH bonding. As a result of the electron beam irradiation, the carrier concentration of ZnO films increased. The on/off ratio was maintained at ${\sim}10^5$ and the $V_{TH}$ values shifted negatively from 11 to 1 V. As the irradiation time increased from 0 to 300s, the calculated S. S. (subthreshold swing) of ZnO TFTs increased from 1.03 to 3.69 V/decade. These values are superior when compared the sample heat-treated at $400^{\circ}C$ representing on/off ratio of ${\sim}10^2$ and S. S. value of 10.40 V/decade.
측정된 기상 조건 데이터를 이용한 지상물체의 표면온도 특성 연구
최준혁,박태원,김태국,Choi, Jun-Hyuk,Park, Tae-Won,Kim, Tae-Kuk 한국군사과학기술학회 2010 한국군사과학기술학회지 Vol.13 No.3
This paper is a part of developing a program that predicts the surface temperature and the IR images of ground objects by considering solar irradiation and atmospheric convection. The thermal modeling is essential for identifying objects on the scenes obtained from the remote sensing. And the temperature distribution on the objects is necessary to obtain their infrared images in contrast to the background. We considered the composite heat transfer modes including conduction, convection and spectral solar radiation incident on the objects within a scene to calculate the surface temperature distribution. The surface temperatures obtained by using the S/W developed in this study(Silhouette) and a commercial S/W(SE-Workbench-IR) are computed and compared each other. Results obtained by using the S/W developed in this study(Silhouette) show fairly good agreement with those obtained by the SE-Workbench-IR.
Design of Secure Information Center Using a Conventional Cryptography
최준혁,김태갑,고병도,류재철,Choi, Jun-Hyuk,Kim Tae-Gap,Go, Byung-Do,Ryou, Jae-Cheol 한국정보보호학회 1996 정보보호학회논문지 Vol.6 No.4
World Wide Web is a total solution for multi-media data transmission on Internet. Because of its characteristics like ease of use, support for multi-media data and smart graphic user interface, WWW has extended to cover all kinds of applications. The Secure Information Center(SIC) is a data transmission system using conventional cryptography between client and server on WWW. It's main function is to support the encryption of sending data. For encryption of data IDEA(International Data Encryption Algorithm) is used and for authentication mechanism MD5 hash function is used. Since Secure Information Center is used by many users, conventional cryptosystem is efficient in managing their secure interactions. However, there are some restrictions on sharing of same key and data transmission between client and server, for example the risk of key exposure and the difficulty of key sharing mechanisms. To solve these problems, the Secure Information Center provides encryption mechanisms and key management policies.
거제도 해양의 여름 및 겨울철 환경에서 거리에 따른 대기투과도를 고려한 함정의 적외선 신호 특성 분석
최준혁,김정호,정인화,이필호,김태국,Choi, Jun-Hyuk,Kim, Jung-Ho,Jung, In-Hwa,Lee, Phil-Ho,Kim, Tae-Kuk 한국군사과학기술학회 2010 한국군사과학기술학회지 Vol.13 No.2
The IR signature data of a ship is mainly affected by location, meteorological conditions(atmosphere temperature, wind direction and velocity, humidity etc.), atmospheric transmittance, solar position and ship surface temperature etc. The IR signatures received by a remote sensor at a given temperature and wavelength region is consisted of the self-emitted component directly from the object surface, the reflected component of the solar irradiation at the object surface, and the scattered component by the atmosphere without ever reaching the object surface. Computer simulations for prediction of the IR signatures of ships are very useful to examine the effects of various sensor positions. In this paper, we have acquired the IR signature for different sensor positions by using computer program for prediction of the IR signatures. The numerical results show that the IR signature contrast as compared to the background sea considering the meteorological conditions, solar and sky irradiations.
대학교 기숙사 생활 만족도에 영향을 미치는 요인: G대학 외국인 학생을 중심으로
최준혁,장영,정화흠,주설군,Choi, Jun Hyuk,ZHANG, YING,ZHENG, HUAXIN,ZHU, XUEJUN 서비스사이언스학회 2012 서비스연구 Vol.2 No.2
많은 대학에서 해외 유학생을 유치하기 위해 노력하고 있다. 우리나라의 외국 유학 중에는 지리적으로 가까운 중국학생이 가장 많은 상황이며, 향후에도 지속적으로 증가할 가능성이 있기 때문에 이를 충족시켜 줄 수 있는 다양한 서비스 제공이 필요한 시점이다. 본 연구는 대학 기숙사를 대상으로 하여, 소음요인, 음식요인 및 시설요인이 유학생들의 기숙사 생활만족도에 어떠한 영향을 주는지에 알아보기 위하여, G대학교 중국유학생을 대상으로 실증 연구를 수행하였다. 분석 결과 음식요인과 시설요인은 기숙사 생활 만족도에 유의한(+) 영향을 미치는 것으로 나타났으며, 소음요인은 유의한 영향을 미치지 않은 것으로 나타났다. 연구 결과를 토대로 외국 유학생을 유치하는 대학에서는, 기숙사에 대한 차별화 전략을 사용할 경우 시설 및 음식 요인에 초점을 맞추는 것이 좀 더 효과적이라고 판단된다. Government and many universities have been trying to get the more international students. Foreign students in university are increasing remarkably in Korea. So these authorities have to consider their service competency for new foreign student's living satisfaction. In this paper, we described about the living satisfaction degree on the university dormitory's service in Korea. After reviewing and summarizing the related literatures, our hypotheses are established which the satisfaction be affected by some service factors such as facility, foods, and noise factors in university dormitory's environments. The 99 Chinese students living in G-university dormitory responded to our study. Empirical analysis was performed among a university in Sungnam city named as G-university by using questionnaires sheets. Analysis results are show that satisfaction degree on the university dormitory's service is affected significantly by facility and foods service factors respectively. However noise factor was not the significant variable.
대기온도 및 풍속 변화에 따른 함정의 적외선 신호 특성 분석
최준혁,이지선,김정호,이성호,김태국,Choi, Jun-Hyuk,Lee, Ji-Sun,Kim, Jung-Ho,Lee, Sung-Ho,Kim, Tae-Kuk 한국군사과학기술학회 2008 한국군사과학기술학회지 Vol.11 No.5
The spectral radiance received by a remote sensor at a given temperature and wavelength region is consisted of the self-emitted component directly from the object surface, the reflected component of the solar irradiation at the object surface, and the scattered component by the atmosphere without ever reaching the object surface. The IR image of a ship is mainly affected by location, meteorological condition(atmosphere temperature, wind direction and velocity, humidity etc.), atmospheric transmittance, solar position and ship surface temperature etc. Computer simulations for prediction of the IR signatures of ships are very useful to examine the effects of various meteorological conditions. In this paper, we have acquired the IR signature for different meteorological conditions by using two different computer programs. The numerical results show that the IR image contrast as compared to the background sea considering the atmosphere temperature and wind velocity.
Cell Disruption of Two Microalgae by Low-frequency Sonication Device
Jun Hyuk Choi(최준혁),Gwang Ho Kim(김광호),Jong Rak Park(박종락),Sang Hwa Jeong(정상화) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.11
The continuous use of fossil fuels along with the development of mankind causes problems related to resource depletion and environmental pollution. Microalgae as one of the alternative energy sources to solve these problems has been studied. Microalgae use inorganic compounds to produce organic matter, and a cell disruption process is required to extract the produced organic matter. Various cell disruption methods exist, among which cell destruction by sonication has been studied. In this study, the disrupting efficiency of Chlorella sp. and Dunaliella salina was compared after sonication. Cell membrane disruption experiments were performed using a low-frequency non-focused ultrasonicator. The experiment conditions were conducted based on the initial optical density of the microalgae. Cell reduction according to time during cell disruption using sonication was fitted by a logistic model, and appropriate conditions for the most efficient cell disruption were determined through three-step experiments.