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Boronizing처리된 STS403 스테인리스강의 표면특성
김광석,이상율 한국 항공대학교 항공산업기술연구소 1999 航空宇宙産業技術硏究所 硏究誌 Vol.9 No.-
STS403강을 pack cementation법에 의해 보로나이징 처리를 실시한 시편의 단면구조는 침붕층(boron diffusion layer), 중간층(intermedium layer), 그리고 기지조직(matrix)으로 구성된다. 침붕층의 표면에서는 주로 FeB가 형성되었으며, 내부로 들어 갈수록 확산되는 보론의 양이 적어져서 Fe₂B가 형성된다. 중간층에서는 국부적으로 Cr의 함량이 매우 높게 나타나는데, 이는 보로나이징 처리시 내부로 확산하는 Cr로 외부로 확산하는 탄소와의 결합으로 형성된 크롬탄화물(Cr23C₃)에 의해 나타난 결과로 사료된다. 보로나이징 처리에 의해 형성된 침붕층의 경도는 Hv1800-2000정도로 매우 높게 나타났는데 이로 인해 고온마모성질이 매우 개선 되었으며, 층붕층에 의해 내부식 특성 또한 향상되었다. STS403 stainless steel substrate was treated by boronizing. Metallographic cross sections of the treated specimens were consisted of boron diffusion layer, intermedium layer, and matrix. Microstructure of boron diffusion layer formed on STS403 was examined by OM, SEM, EDS, XRD and surface properties of boron diffusion layer was evaluated by micro-vickers hardness tester, wear tester and corrosion tester. From the XRD analysis of the boron diffusion layer, phases such as FeB, Fe₂B were identified. The result from EDS analysis showed that intermedium layer contained much more Cr than any other layers. The activation energy for the diffusion of boron in the STS403 steel was calculated to be approximately 160kJ/mole. Microhardness of boron diffusion layer was measured to be approximately Hv1800∼2000(50gf). On high temperature wear testing at 600˚C, boronizing treated specimen exhibited an excellent wear resistance, showing that the wear volume of the boronizing treated specimen was approximately five times smaller than that of untreated specimen. From the result of anodic polarization curves in 1M, H₂SO₄solution, boronizing treated specimen showed an excellent corrosion resistance than the STS403 stainless steel. From the result of anodic polarization curves in 1M, H₂SO₄solution, boronizing treated specimen showed an excellent corrosion resistance than the STS403 stainless steel.
朴鍾烈,趙光濟 경북대학교 교육대학원 1987 논문집 Vol.19 No.-
Systems Analysis Models have been recognized as most effective tools which can analyze and examine the complex educational Systems. The purpose of this study is to examine the System Analysis Models of Educational Administration, and to construct the Comprehensive Systems Analysis Models of Educational Administration which can analyze and describe Korean Educational Administration System it terms of organizational level. The Educational Administration System as hierarchy may be divided into four subsystem such as Educational Policy System, Educational Management System, School Management System, and Classroom Management System. The Contents of 4 Systems Analysis Models of Educational Policy were developed by Easton, Campbell, Dror, and Sharkansky, 3 Systems Analysis Models of Educational Management, by Kaufman, Owens, and Kim Jong-Chul, 3 Systems Analysis Models of School Management, by Kimbrough, Hoy & Miskel, Lipham & Hoeh, and 2Systems Analysis Models of Classroom Management, by Lemlech, and Kim Se-Kee, respectively, were examined in this study. On the basis of examined contents of above Systems Analysis Models, These writers attempted to construct a Systems Analysis Model of Educational Administration in terms of organizational level. (See figure 14) The model, Comprehesive Model for Systems Analysis of Educational Administration, may be used as an useful Systems Analysis Model in order to adapt and analyze for Korean Educational Administration System.
권광일,윤민혁,윤희열,박희찬,권준택,심희옥,김동출 충남대학교 약학대학 의약품개발연구소 2004 藥學論文集 Vol.19 No.-
A reversed phase HPLC method was developed and validated for the determination of primidone in human plasma. Propylthiouracil was used as an internal standard. Calibration curves were linear in the concentration range of 10-120 ng/㎖. The coefficient of variation of the intra- and inter-day precision were below 15%. The coefficient of variation of the accuracy were below 15% in the concentration range investigated. A bioavailability study was performed using the validated HPLC method. Twenty four healthy human male volunteers were orally administered 20 mg of primidone. The pharmacokinetic parameters were calculated using WinNonlin. The mean values of AUC_(LAST) was 85.0±17.7 ㎍ hr/㎖, C_(max) was 4.22±1.04 ㎍/㎖, T_(max) was 1.85±1.13 hr, t_(1/2) was 17.7±2.4 hr. The pharmacokinetic parameters and the HPLC method can be used for the desigm of bioequivalence study of primidone.
전기충격요법후 혈중 Prolactin에 대한 Methysergide의 영향
유태열,방승규,박원명,한진희,이수정,김광수 대한신경정신의학회 1991 신경정신의학 Vol.30 No.2
Recently it has been shown in numerous experimental studies that a series of electroconvulsive therapy(ECT) affects neurohormonal function in man, though its mechanism was yet unknown. To investigate effects of methysergide on serum prolactin response after ECT, the authors studied the change of the serum levels of prolactin before ECT(the day before ECT) and after ECT, with and without methysergide pretreatment by RIA method in 11 psychiatric patients. ECT was given with the electrodes placed in the bitemporal position using a pulse current delivering device(Thymatron). The results were as follows; 1) Compared with the day before ECT, serum prolactin levels were increased significantly at 15, 30, 60 minutes after ECT(P〈0.01). 2) Compared with ECT alone, serum prolactin levels were attenuated significantly at 15,30,60 minutes after ECT with methyserigide(P〈0.05. P〈0.01). Hormonal responses of this study in terms of the knowledge availakle on the neurotransmitter control of prolactin release suggests that the responses of prolactin to ECT may be mediated by the activation of serotonergic system in central nervous system.
김광우,이문섭,김중렬,이순제 강원대학교 부설 석재복합신소재 제품연구센터 2002 석재연 논문집 Vol.7 No.-
본 연구는 정하중하에서 아스팔트 혼합물의 소성변형 저항특성을 측정할 수 있는 새로운 시험방법을 개발하기 위하여 수행되었다. 2가지 골재(편마암, 화강암)와 6가지 아스팔트(일반아스팔트, 5가지 개질 아스팔트)를 사용하여 총 12개의 밀입도 혼합물을 제작하였다. 마샬 배합설계를 통해 최적아스팔트 함량을 구하고, 결정된 최적아스팔트 함량으로 마샬공시체(S=10 cm)와 자이레토리 공시체(S=15cm)를 제작하여 마샬안정도시험, 휠 트랙킹 시험, 개발된 김테스트(Kim -test)를 수행하였다. 김테스트는 공시체와 하중봉을 지지할 수 있는 김시험장치(Kim tester)를 이용하여 하단이 반경(r) 0.5 또는 1.0cm로 원형절삭한 직경(D) 3cm, 4cm의 하중봉을 사용한다. 또한 재하는 마샬 하중재하 장치를 사용하여 공시체를 60℃ 수조에 30분동안 수침시킨 후 실시되었다. 정하중은 공시체의 직경방향이 아닌 축 방향으로 50 mm/min가 가해졌고, 최대하중(P_max)과 수직변형(y)이 측정되었다. 마샬안정도시험과 간접인장강도시험에서 얻어지는 것과 유사한 곡선이 각각의 시험에서 얻어졌다. 강도값은 P_max, r, y 및 H(=D-2r)을 이용한 K_D=4P_max/π(H+2√(2ry-y^2))^2식을 통하여 계산하였고, 이를 변형강도(kgf/㎠)로 정의하였다. 실험결과, 공시체 직경이나 골재종류보다는 하중봉과 하중봉 하단의 원형처리 여부가 K_D와 P_max 값에 영향을 미치는 것으로 나타났다. 통계분석결과에서 K_D가 소성변형 깊이와 동적 안정도에 높은 상관성을 보였다. 향후 연구를 통해 K_D의 유효성이 검증된다면, Kim-test는 아스팔트 혼합물의 소성변형 저항성을 판단할 수 있는 시험방법으로 사용될 수 있을 것이다. This study dealt with developing a new approach for finding properties which might represent rut resistance characteristics of asphalt mixture under static loading. Two aggregates, a normal asphalt (pen 60-70) and 5 PMAs were used in preparation of 12 dense-grade mixtures. Marshall mix design was used in determination of the optimum asphalt content (OAC) and each mixture at the OAC was prepared for a newly-developed Kim test on Marshall specimen (S=10 cm) and gyratory specimen (S=15cm), and for wheel tracking test. Kim test used Marshall loading frame and the specimen was conditioned for 30min at 60℃ before loading through Kim tester, and apparatus consisting of a loading column and a specimen and column holder. Diameter (D) of column was 3cm and 4cm with each column having different radius (r) of round cut at the bottom. The static load was applied at 50mm/min in axial direction of the specimen, not in diameteral direction, and the maximum load (P_max) and vertical deformation (y) at the maximum load point were measured. A curve, similar to the one from a Marshall test or static indirect tensile strength test was obtained from each test. A strength value was calculated based on the P_max, H(=D-2r). r and y by using the equation K_D=4P_max/π(H+2√(2ry-y^2))^2 and is defined as deformation strength (kgf/㎠). The values of P_max/y and K_I=K-D/y were also calculated to see if these have any correlation with rutting. In general, D and r were significant factors affecting K_D, while specimen size was not. The statistical analyses results showed the K_D had the best correlation with rut depth and dynamic stability. The next best correlation was found from P_max which was followed by P_max/y and K_I in order. Therefore, K_D can be used for selecting the highly resistable asphalt mixture against permanent deformation.
정신분열증 환자의 전산화 단층촬영상 대뇌 비대칭성과 대뇌 위축과의 관계
유태열,한진희,채영래,김광수,노왕구 大韓神經精神醫學會 1991 신경정신의학 Vol.30 No.3
Since the advent of computed tomography(CT). there have been growing evidences of cerebral structural abnormalities in schizophrenics. Among them. reversed hemispheric asymmetry has been regarded as impaired cerebral lateralization of schizophrenics representing another pathology different from brain atrophy. To investigate the pattern and frequency of reversed cerebral asymmetry and their relationship with brain atrophy. we analyzed widths of frontal and occipital region on the brain CT scans of right-handed 56 schizophrenics and 52 normal controls by a manual method. Brain atrophies were assessed using fixed arm planimetry and visual lineat measurements. Compared to normal controls. the schizophrenics show significantly increased frequency of reversed occipital asymmetry. Dividing the schizophrenics into group according to the evidences of atrophy revealed more reversed occipital asymmetry than those with brain atrophy. These findings suggest that reversed cerebral asymmetry might be unrelated to brain process and would be a neuroanatomic evidence of abnormal asymmetry of schizophrenices.