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Anatase TiO$_2$박막의 미세조직이 광촉매 효과에 미치는 영향
최용락,김선화,Choe, Yong-Rak,Kim, Seon-Hwa 한국재료학회 2001 한국재료학회지 Vol.11 No.7
$TiO_2$광촉매릉 반응성 스퍼터링법을 이웅하여 박막으로 제조하고 유기물 및 살균실험을 통하여 미세조직이 광촉매 효율에 미치는 영향을 조사하고자 하였다. 광촉매 효율측정을 위하여 페놀분해실험 및 E.coli 078을 이용한 살균실험을 행하였다. $TiO_2$박막에 의한 페놀분해실험 시, 전자수용체인 산소의 공급에 의하여 분해효율이 2배까지 증가하였다. E.coli 078분해실험의 경우, 광촉매 $TiO_2$박막을 사웅하여 살균하였을때 UV만 조사하여 살균하였을 경우 보다 분해효율이 최고 70% 이상 증가하였다. 페놀분해실험과 E.coli 078 살균실험 결과 저결정성 박막의 경우 분해능이 매우 미약하였으며, 표면조도가 높고 결정성이 우수한 박막의 경우에 높은 광촉매 효율을 나타내어$TiO_2$박막의 광촉매 효과는 표면형상과 결정성이 매우 중요한 인자로 작용하였다. Anatase $TiO_2$thin films as a photocatalyst were prepared by the reactive magnetron sputtering process. The $TiO_2$thin films were deposited on Si substrates under the various conditions : oxygen partial pressure, working pressure, sputtering time, and D.C. power. The photocatalystic degradation of $TiO_2$thin film have been studied to examine the contribution of surface morphology and crystallinity. The thin films with a good crystallinity or a rough surface showed a high photocatalytic degradation rate on phenol and E.coli 078 experiment. Compared with that of only UV radiation, the photocatalytic efficiency of $TiO_2$thin film under the UV radiation and the $O_2$ flow increased. We found that the crystallity and the morphology were the important factors on the photocatalytic efficiency of TiO$_2$thin film.
최용락,고병수,박명찬,Choe, Yong-Rak,Ko, Byong-Su,Park, Meong-Chan 대전대학교 군사연구원 2003 군사학연구 Vol.1 No.-
While the social activities using Internet become generalized, the side effect of the information security violation is increasing steadily and threaten the countries which is not ready to prevent from offensive penetration such as the Information-fighter or Cyber-military. In this paper, we define the concept and characteristics of the modern Information-Warfare and analyze various kinds of threatened elements and also examine the recent trend in other countries. And introducing Computer Forensics raised recently for the confrontation against the security violation in the future, we will show the developing strategies and the necessity in order to response cyber attacks. These developing strategies can be used to ensure and re-trace the technical evidence for the security violation and to achieve the disaster relief effectively. So we hope that can apply them to the actual preparation through developing cyber trial test of the defense and attack for the Information-Warfare.
최용락,김창희,이재범,최원재,승홍민,박노철,하종문 한국비파괴검사학회 2023 한국비파괴검사학회지 Vol.43 No.4
Research on vibration-based gearbox fault diagnosis using artificial intelligence (AI) has been actively conducted in recent years. However, a problem exists whereby the performance of AI models that have been optimized to solve certain problems such as classification based on the pattern analysis of training data can be significantly degraded when the characteristics of the measured vibration signals are varied by the various changes in the operating environments. In this study, a physics-based kernel that can extract fault-related features based on physical information on the defect characteristics is designed. Unlike typical AI model kernels, the proposed physics-based kernel was fixed to prevent it from being learned, allowing physical information to be reliably extracted. This allows the development of a robust gearbox fault diagnosis in various domains, including non-stationary operating conditions that occur in actual industrial settings. The proposed idea was the validated on a gearbox testbed operated under various operating conditions. Consequently, the proposed method outperforms the conventional method, while retaining its physical robustness and capability for accurate gearbox fault diagnosis. 최근 인공지능을 활용한 진동 기반 기어박스 고장진단에 대한 연구가 활발히 진행되어왔다. 하지만학습용 데이터의 패턴을 분석하여 분류 등의 주어진 문제를 해결하도록 최적화되는 인공지능 모델의 특성상, 운용환경 변화에 따라 측정되는 진동신호의 특성이 달라지는 경우 성능이 크게 저하될 수 있다는 문제가제기되어 왔다. 본 연구에서는 기어박스 결함으로 인해 발생할 수 있는 현상의 물리적 특성을 고려하여 인공지능의 성능을 향상시킬 수 있는 방법론을 제안한다. 이를 위해 결함 특성에 기반한 물리 정보를 통해 특성인자를 추출할 수 있는 물리 기반 커널을 설계하였다. 제안된 물리 기반 커널은 일반적인 인공지능 모델의커널과는 다르게 학습이 불가하도록 고정되어 보다 강건하게 물리 정보를 추출할 수 있다. 이를 통해, 실제산업 현장에서 발생하는 비정상 운용조건 등의 다양한 도메인 변화 문제에 대해 강건한 기어박스 고장진단을 수행할 수 있도록 하였다. 제안된 기법의 검증을 위해 다양한 운용조건에 대한 기어 테스트베드 실험을수행한 결과, 제안 방법을 통해 운용조건 변화에 무관하게 물리적으로 유의미한 결함 인자가 추출되며 이에따라 강건한 기어박스 고장진단이 가능함을 확인하였다.
반응성 스퍼터링법으로 제조된 anatase TiO$_2$박막의 미세조직에 관한 연구
최용락,김선화,이건환,Choe, Yong-Rak,Kim, Seon-Hwa,Lee, Geon-Hwan 한국재료학회 2001 한국재료학회지 Vol.11 No.9
Anatase $TiO_2$ thin films as a photocatalyst were prepared by the D.C reactive magnetron sputtering process. The $TiO_2$ thin films were deposited on Si(100) substrates under the various conditions : oxygen partial pressure, working pressure, substrate temperature, D.C power, and deposition time. The morphology of the TiO$_2$ thin films showed an island structure. At early stages of film growth, amorphous phase formed. However, during the further growth, columnar crystalline $TiO_2$grains evolved. The crystallinity of the thin films depended on the oxygen partial pressure, the working pressure and the D.C. powers.
분산 시스템 환경의 인증 서비스 및 실체 인증 메커니즘 분석
최용락 大田大學校 産業技術硏究所 1996 산업기술연구소 論文集 Vol.7 No.2
A distributed system is susceptible to a variety of security threats mounted by intruders as well as legitimate users of the system. This paper deals with authentication services in a distributed system. By reviewing some basic authentication requirements and comparing several authentication schemes, we can make the consideration of main design issues for a complete cryptographic-based authentication mechanism. In this paper, the various types of masquerade and replay attacks among the communication entities are analyzed in the related authentication mechanism such as Kerberos, X.509, Difffie&Hellman, PGP and SPX.
催龍洛 大田大學校 産業技術硏究所 1994 산업기술연구소 論文集 Vol.1994 No.8
This thesis studies on the period transformation algorithm. Rate-monotonic algorithm was proved to be the optimal static priority scheduling algorithm for periodic process. Under dynamic environment, both earliest deadline and least laxity scheduling algorithm were proven to be optimal dynamic proirty scheduling algorithm. In spite of the optimality, property none of these algorithm are widely used in practice. This is, is part, because a direct application of these algorithm leads to many practical problems which have not been fully addressed in the literature. But, by the period transformation on the basis rate monotonic algorithm, this problem was solved easily. Though this algorithm has low efficiency, simulation result was proven that nonperiodic deadline was guranteed all.