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김교한,허만수,김형일,황운석,高田 雄京,奧野 攻 대한치과기재학회 1999 대한치과재료학회지 Vol.26 No.4
One of the fields in which titanium(Ti) is becoming increasingly valuable is the field of biomaterials. Ti had shown its good corrosion resistance, high strength to weight ratio, and compatibility with human tissues. Such applications of Ti in this area involve replacing stainless steel and cobalt-chromium alloy implant which are used in skull, shoulder joint, spine, and dental implant. In dental field, titanium has been used as dental implant, so it becomes necessary to examine and estimate the anti-corrosion ability of Ti and its alloys at the severe conditions such as crevice corrosion and galvanic corrosion. The purposes of this study was to examine the corrosion mechanisms of the pure Ti showing good corrosion resistance under an oral corrosion environment when it is coupled with dental casting Type Ⅱ and Type Ⅳ gold alloys. These coupling corrosion mechanisms were studied in three conditions. First was by measuring the resting potential of pure Ti, when it was uncoupled and coupled with Type Ⅱ and Type Ⅳ alloys. Second was by measuring anode polarization behavior of pure Ti, Type Ⅱ and Type Ⅳ alloys, and third was by detecting dissolved ions from the pure Ti, uncoupled and coupled with Type Ⅱ and Type Ⅳ gold alloys which were immersed in 0.9% NaCl solution for 7 days. The resting potential showed a low potential value at the initial stage but increasing into a high value (to 0.18 V) with time elapse and reached a stable value. On the contrary, the potentials of Type Ⅱ and Type Ⅳ gold alloys were in their values at the initial stage of immersion, then decreased with the time and reached stable values, being higher than the value of pure Ti. When pure Ti coupled with Type Ⅱ and Type Ⅳ gold alloys, the resting potential of coupled one was between the values of each one. When Type Ⅱ and Type Ⅳ gold alloys were coupled with pure Ti, there was an increase in Ag, Cu, and Zn. Also, Zn ions released the high potential precious metal alloys, compared to the uncoupled case. Ti ion was not detected at any cases of pure Ti or coupled with gold alloys. It was thought that one of the causes of the increase in Ag, Zn, and Cu ions when Ti was coupled with dental gold alloys was that Ag, Zn, and Cu ions were selectively dissoluted from the Ag rich regions around grain boundary and the casting defects. In conclusions, the results of this study suggest that the pure Ti was very stable when coupled with the gold alloys in oral cavity.
광학적 투명성을 가진 ITO를 에미터 전극으로 사용한 InP/InGaAs HPT's의 DC 특성 분석
강민수,한교용 영남대학교 공업기술연구소 2001 工業技術硏究所論文集 Vol.29 No.1
InP/InGaAs Heterojunction phototransistors(HPT's) with an optically transparent ITO emitter electrode were fabricated and characterized. At the same time, heterojuntion transistors(HBT's) having the same device layout were fabricated. By comparison with InP/InGaAs HBT's, the dc characteristics of InP/InGaAs HPT's showed the similar electrical characteristics of HBT's. The model parameters of the device were extracted and compared.
농작물 해충 및 진균류 방제를 위한 방선균의 분리 및 동정
이은정,강경돈,황교열,김두호,김신덕,성수일 한국잠사학회 1998 한국잠사곤충학회지 Vol.40 No.1
Twenty seven out of ca. 5,000 actinomycete strains, which were isolated from soil collected throughout the country, showed antimicrobial effects against fungi, Rhizopus stronifer (ATCC6227a), Rhizoctonia solani (KCCM 11271) and yeast, Candida albicans(ATCC10231). From these antifungal microorganisms, we further selected seven strains which seemed to produce insecticidal substances with in vivo test, using silkworm, Bombyx mori and beet armyworm, Spodoptera exigua. Morphological and biochemical experiments revealed that three strains out of seven were streptomyces. Further investigations on the physical and chemical properties of these antifungal and insecticidal substances are now in progress.
이필호,이구연,전철수,연규석,이윤수,인교진 강원대학교 부설 석재복합신소재 제품연구센터 2000 석재연 논문집 Vol.5 No.-
본 연구는 1993년부터 춘천시 신동면 형돌리 산 62번지 내에서 흑운모 화강암 및 편마암 암석을 원자재로 사용하여 건설기초재료인 쇄설골재 및 인공모래를 생산하는 업체로부터 제품 생산 후 발생하는 토양 스러치 케익이 연간 약 10만 입방정도 발생한다는 사실에 기초하여 석산에서 채취된 페잔토(석분)의 화학적, 물리적, 역학적 특성을 조사하여 석분의 이용 가능성을 확인하기 위한 실험으로 단위 시멘트량을 400kg, 잔골재율을 45% 그리고 물-시멘트비를 65%로 고정하고 잔골재 중 석분을ㄹ 0%, 10%, 20%, 30%, 40%, 50% 및 60%로 치환하여 제조된 콘크리트의 기초적 성질을ㄹ 시험하였다. 그 결과 석분의 치환율이 높을 수록 공기량은 증가하고 슬럼프값이 감소하였는데 이는 미세한 입자인 석분을 잔골재의 일부로 치환함으로써 비표면적이 증가하였기 때문인 것으로 사료된다. 압축강도와 휨강도는 모두 석분의 치환율이 증가할수록 압축강도와 휨강도는 다소 감소하는 경향을 나타냈으나 큰 성능차이는 보이지 않는 다는 것을 알 수 있었다. 이상의 실험을 통해 석분을 시멘트 콘크리트에 사용했을 경우 약간의 성능저하는 있지만 잔골재로의 활용이 가능하다는 것을 알 수 있었다. 그러므로 앞으로 건조수축, 균열, 크리이프 특성 및 내구성에 과한 연구가 더욱 심도있게 이루어져야 폐자원인 석분의 이용이 가능하리라 판단된다. This study aims to make cement concrete using crushed stone fines which are produced at Chuncheon city, Hyuldongri and find it's applications. According to the experimental results, when ratio of crushed stone fines was increased, air contents were increased and slump values were decreased. Also, the compressive strength and flexural strength were decreased when ration of crushed stone fines was increased. Although these strengths are decreased, the crushed stone fines can be used to construction materials because the decreased amounts are not so much.
( Su Bin Park ),( Kyo Hwa Kang ),( Hyo Jin Park ),( Jong Soon Park ),( Su Hak Heo ),( Hong Kim ),( Young Bin Choy ),( Chan Yeong Heo ) 한국조직공학·재생의학회 2011 조직공학과 재생의학 Vol.8 No.4
Bioabsorbable plates and screws for bone fixation system have been used owing to many advantages over conventional metallic devices. This study investigated the effects and safety of recently developed modifiable bioabsorbable plate and screw made of 100% poly (L-lactic acid) in the healing process of mandible fracture in arabbit model. In vitro extract test for cytotoxicity and bacterial reverse mutation test for genotoxicity were carried out. Any cytotoxicity caused by extract from experiment sample was not observed. In genotoxicity test, increase in the number of revertants was not observed. As an in vivo test, plates and screws were used for rigid fixation of exper-imental mandible fracture in twenty rabbits. Tissue specimens with plate were taken from the rabbits after 4, 6, 8,10 weeks and histological analysis was studied. After 4 weeks, the plate was covered by connective tissue and severe chronic active inflammation in soft tissue was observed. After 6 weeks, absorbed part in plate and new bone forma-tion around periostium and decrease in inflammation were detected. After 10 weeks, new bone formation was observed in all samples and the thickness of bone increased. The remodeling was not complete yet. This study dem-onstrates that recently developed biodegradable plate and screw system made of poly(L-lactic acid) was effective in mandible fracture regions known as high load-bearing areas. This indicates that bioabsorbable poly (L-lactic acid) plates and screws are available for most of bone fractures, although the adjustment process and long-term follow-up study are necessary for clinical application.
Reliability-Based Optimum Tolerance Design for Industrial Electromagnetic Devices
Su-Gil Cho,Junyong Jang,Su-Jin Lee,Kyu-Seob Kim,Jung-Pyo Hong,Woo-Kyo Jang,Tae Hee Lee IEEE 2014 IEEE transactions on magnetics Vol.50 No.2
<P>Principle of tolerance design is receiving increased research focus to determine the optimal tradeoff between manufacturing cost and quality. However, current tolerance designs are not suitable for products such as electromagnetic devices that require high reliability, i.e., a very low failure rate. In this paper, a new tolerance design named as reliability-based optimum tolerance design is formulated and performed to guarantee the high reliability of the products while maximizing manufacturing tolerances. The proposed method quantifies the reliability using reliability analysis, which reflects the tolerance in the tolerance design. To validate the proposed method, tolerance design is applied to two examples: 1) a magnetic circuit ( C -core) and 2) a mass-produced interior permanent magnet motor that contains manufacturing tolerances of permanent magnet.</P>
Isolation and Purification of Polyhydroxylated Alkaloids from Silkworm (Bombyx mori L.)
( Hyun Su Kim ),( Hyun Jung Ko ),( Yong Seak Cho ),( Jae Yeon Lee ),( Kyo Yeol Hwang ),( Jin Won Kim ),( Heui Sam Lee ),( Ik Soo Kim ),( Kang Sun Ryu ),( Young Ho Kim ),( Su Il Seong ) 한국잠사학회 2003 International Journal of Industrial Entomology Vol.7 No.2