치과주조용 Ag-Pd-Zn-Sn-In 합금의 시효경화 특성

이재호,김명진,이희경,김형일,설효정 大韓齒科器材學會 2004 대한치과재료학회지 Vol.31 No.1

Cu가 첨가되어 있지 않고, 대신에 상대적으로 많은 양의 Zn 그리고 소량의 Sn과 In이 첨가된 치과주조용 Ag-Pd-Zn-Sn-In 합금의 시효경화 특성을 경도 시험, X선회절 실험, 주사전자현미경 관찰, 전자탐침 미소분석법으로 조사하여, 다음과 같은 결과를 얻었다. 1. 950℃에서 용체화처리된 시편을 500℃와 550℃에서 등온시효처리하면, 시효 초기에 경도가 완만히 상승하여 최고 경도에 도달하였고 최고 경도를 일정 기간 유지하고 나서 서서히 하강하였다. 2. 용체화처리된 시편은 Pd 원자가 고용된 Ag-rich α1상, Pd3Sn인 α2상, Pd2Zn인 α3상의 3상 공존이었고, 등온시효처리함에 따라 Ag-rich α1상에서 Pd-rich 상으로 추정되는 β상이 석출하였다. 3. 시효 초기의 경화는 Ag-rich 기지에서 Pd-rich 상의 석출로 인한 격자변형에 기인하는 것으로 추정된다. 4. 시효처리 시간을 연장함에 따른 과시효 연화는 입계에 Ag-rich α1상과 Pd-rich β상으로 된 층상조직의 석출과 조대화에 기인하였다. 5. Pd3Sn인 α2상과 Pd2Zn인 α3상은 시효경화에 기여하지 않았다. Age-hardening characteristics of a dental casting Ag-Pd-Zn-Sn-In alloy without copper (52.0 wt% Ag - 39.9 wt% Pd - 4.0 wt% Zn - 2.0 wt% Sn - 2.0 wt% In - 0.1 wt% Ir) was investigated by means of hardness test, X-ray diffraction study, scanning electron microscopic observations and electron probe microanalysis. The specimen solution-treated at 950℃ was three phases of the Ag-rich α1 phase containing Pd element, the α2 phase based on Pd3Sn and the α3 phase based on Pd2Zn, and the Pd-rich β phase was precipitated from the Ag-rich α1 phase by the isothermal ageing,. The initial hardening seemed to be attributed to coherency strains which were formed in the Ag-rich matrix by the precipitation of Pd-rich phase. Overageing with softening was due to the formation and coarsening of the lamella precipitates at grain boundaries, which were composed of the Ag-rich α1 and Pd-rich β phases. The α2 phase based on Pd3Sn and the α3 phase based on Pd2Zn did not contribute to the age-hardening of this alloy.

2-(N, N- dimethylamino) phenyl triisopropoxy titanium 화합물의 카르보닐 화합물에 대한 첨가 반응 연구

이근설,김희정 상명대학교 기초과학연구소 1992 기초과학연구 Vol.7 No.-

카르보음이온 화학은 탄소-탄소 결합을 형성하는 유기합성분야에서 가장 중요한 부분중의 하나이다. 고전적인 카르보음이온, 예를들어 알킬리튬 또는 Grignard시약은 카르보닐 화합물에 대해 높은 반응성을 나타내는 반면 낮은 선택성을 갖는다. 반면에 RTiX₃(R=methyl, allyl)로 표현되는 유기티타늄 화합물은 카르보닐 화합물에 대해 화학적이고 입체적인 선택성이 높은 것으로 알려졌다. 본 연구에서는 2-(N, N-dimethylamino phenyl) triisopropoxy titanium을 합성하여 이것의 카르보닐 화합물에 대한 반응성을 본 결과 다른 유기티타늄 화합물과 같이 알데히드 화합물에 선택적인 반응성을 나타내는 것을 알수있었다. Carbanion chemistry is one of the most important field in organic synthesis, expecially for the formation of C-C bond. Though the classical carbanions, for example alkyllithium or Grignard reagent, Show high reactivity for the carbonyl compounds, but they react with low selectivity. On the other hand, it is well known that organotitanium compounds generally expressed as RTiX₃(R=methyl, allyl) have high chemo-and stereoselectivity. In this study 2-(N, N-dimethylamino phenyl) triisopropoxy titanium was prepared in situ from 2-(N, N-dimethylamino) phenyllithium and chloridetriisopropoxytitanium and was added to carbonyl compounds in order to investigate its reactivity. As a result this reagent was proved to have the same aldehyde reactivity as the other organotitanium compounds.

카르보닐화합물에 대한 유기티타늄화합물의 화학선택성에 대한 연구

이근설,김희정 상명대학교 기초과학연구소 1992 기초과학연구 Vol.6 No.-

카르보음이온 화학은 탄소-탄소 결합을 형성하는 유기합성분야에서 가장 중요한 부분중의 하나이다. 고전적인 카르보음이온, 예를 들어 알킬리튬 또는 Grignard 시약은 카르보닐화합물에 대해 높은 반응성을 나타내는 반면 낮은 선택성을 갖는다. 반면에 RTiX3로 표현되는 유기티타늄 화합물은 카르보닐 화합물에 대해 화학적이고 입체적인 선택성이 높은 것으로 알려졌다. 본 연구에서는 trichlorophenyltitanium을 합성하여 이것의 카르보닐 화합물에 대한 반응성을 본 결과 다른 유기티타늄 화합물과 같이 알데히드 화합물에 선택적인 반응성을 나타내는 것을 알 수 있었다. Carbanion chemistry is one of the most important field in organic synthesis, expecially for the formation of C-C bond. Though the classical carbanions, for example alkyllithium or Grignard reagent, show high reactivity for the carbonyl compounds, but they react with low selectivity. On the other hand, it is well known that organotitanium compounds generally expressed as RTiX₃(R=methyl, allyl) have high chemo-and stereoselectivity. In this study trichlorophenyltitanium was prepared in situ from phenyllithium and titaniumtetrachloride and was added to carbonyl compounds in order to investigate its reactivity. As a result this reagent was proved to have the same aldehyde reactivity as the other organotitanium compounds.

경동맥 내막 절제술 후 발생한 과관류 증후군 1예

송희정,박광열,정진상,조수진,이순정,허승,김동익,이광호,이병붕 대한신경과학회 1999 대한신경과학회지 Vol.17 No.2

구멍이 있는 공작물의 가공시 형상특성

이종선,원종진,안운상,홍석주,윤희중 한국공작기계학회 2002 한국생산제조학회지 Vol.11 No.5

This study is to investigate the characteristics of the surface around a hole and outlet of product which are manufactured by face mill or end mill cutting with a hole or a pocket in its surface. Furthermore, experiments for optimization of process conditions to minimize the change of characteristics of milling cut surface after a hole cutting operation are implemented. This result is apply manufacture of mold products and metal products by diecasting.

모델 리파지토리를 이용한 기업지식경영 : P사 적용 사례를 중심으로 P Company Case

정재우,이희석 한국경영과학회 1999 經營 科學 Vol.16 No.2

The management of enterprise knowledge has been increasingly important because knowledge emerges as the new basis of competition in postcapitalist society One of the key issues in knowledge management is to put knowledge into a repository where it can be easily stored, reused, and recreated This paper proposes a model repository and the corresponding knowledge management framework The emphasis of model repository is on abstracting knowledge in the form of schematic models Two major benefits are model independence and model integration A metascherma is constructed according to six conceptual components separate unit, external link, internal link, separate unite descriptor, link descriptor, and composite descriptor, which can be applied for a variety of models A prototype system with a case illustrates the practical usefulness of model repository for knowledge management

폐농양 및 복부농양을 일으킨 Eikenella corrodens 감염 2예 : Two Case Reports and Review

정용희,류미숙,김영식,이우인,이희주,서환조 대한화학요법학회 2000 대한화학요법학회지 Vol.18 No.1

Eikenella corrodens is a slowly growing, facultative anaerobic gram-negative bacillus. It is a normal inhabitant of the human upper respiratory tract, and it is recognized as an infrequent cause of invasive disease. To date, a few cases of E. corrodens infection were noted from all other organ. We report herein two cases of E. corrodens infection. In one case E. corrodens was isolated in the lung abscess and in the other case it was in the appendiceal abscess. The patients were treated empirically with penicillin G. The results of the bacterial culture and sensitivity test were available with it. The patients were discharged 15 days later with marked improvement after treatment. Our report clearly demonstrates that E. corrodens can be the pathogen of lung abscess and intraabdominal abscess. We reviewed descriptions from the literature of infections caused by E. corrodens.

食餌中의 Sucrose와 冠狀心臟病과의 關係

이정원,정영진,이주희 충남대학교 자연과학연구소 1980 學術硏究誌 Vol.7 No.2

Diet has been convinced to be an influential environmental factor of the development of coronary heart disease (CHD), though it is still on debate. The related dietary components include total fat, saturated fat, cholesterol, animal protein, fiber, and sugar. During last 50 years, most of the dietary studies concerning atherosclerosis and CHD have emphasized the role of fats. In recent years, however, the effect of sucrose on the development of CHD has received considerable attentions. In 1957 a significant positive association of sugar consumption with the coronary mortality was first pointed out by Yudkin in London. Since then, various epidemiologic and experimental studies have been carried out upon their relationships and have suggested the hyperlipidemic effect of sucrose as a possible etiologic factor of CHD In order to learn to what extent dietary sugar influences the development of CHD in man, the evidences were reviewed under three headings. First, interrelations between the intake of sucrose and the CHD incidence: second, experiments in man and in animals: finally, suggested possible metabolic mechanisms.

CMS에서 전력제어를 위한 AGC의 성능 개선에 관한 연구

이원구,이철희,천종훈,박수봉,박종안,신용길 조선대학교 동력자원연구소 1996 動力資源硏究所誌 Vol.18 No.1

CDMA 시스템에서는 이동국이 Open-loop 전력제어 및 Close-Loop 전력제어를 할 때 비 선형적인 AGC의 특성으로 인해 수신기의 감도가 현저히 낮아진다. 본 논문에서는 AGC의 비선형적인 특성 곡선값을 S/W로 선형화 시켜 RAS RAMDATA를 생성하고 이를 RAS RAM에 넣어 선형적으로 보상된 AGC특성을 얻는 알고리즘을 제안하였다. 그리고 실험을 통하여 그 유효성을 증명한다. In CDMA system, the sensitivity of receivers is lowered significantly due to characteristics of non-linear AGC when the mobile station implements open-loop power control and closed-loop power control. In this paper, We propose a algorithm that obtains linearly conpensated AGC characteristic by inserting the RAS RAM DATA in RAS RAM, which linearizes the value of non-linear characteristic graph in AGC by S/W, and the experimental results shows the validity.

보강된 복합적층 원통형패널의 좌굴거동

이종선,원종진,홍석주,윤희중 한국공작기계학회 2003 한국생산제조학회지 Vol.12 No.5

Bucking behavior of stiffened laminated composite cylindrical panel was studied using linear and nonlinear deformation theory. Various buckling load factors are obtained for stiffened laminated composite cylindrical panels with rectangular type longitudinal stiffeners and various longitudinal length to radius ratio, made from Carbon/Epoxy USN150 prepreg and are simply-supported on four edges under uniaxial compression. Buckling behavior design analyses are carried out by the nonlinear search optimizer, ADS.