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생체의학 임플란트재료로서 Ti-Nb계 합금의 조직과 기계적 성질에 미치는 HEMM의 영향
우기도,최갑송,이현범,김인용,Woo, Kee-Do,Choi, Gab-Song,Lee, Hyun-Bum,Kim, In-Yong,Zhang, Deliang 한국재료학회 2007 한국재료학회지 Vol.17 No.11
Al-42wt%Nb powder was prepared by high-energy mechanical milling(HEMM). The particle size, phase transformation and microstructure of the as-milled powder were investigated by particle size distribution (PSD) analyzer, scanning electron microscopy (SEM), X-ray diffractometery (XRD), transmission electron microscopy (TEM)and differential thermal analysis (DTA). The milled powders were heated to a sintering temperature at 1000C with under vaccum with vaccum tube furnace. Microstructural examination of sintered Ti-42wt%Nb alloy using 4h-milled powder showed Ti-rich phases (${\alpha}$-Ti) which are fine and homogeneously distributed in the matrix (Nb-rich phase: ${\beta}$-Ti). The sintered Ti-42wt%Nb alloy with milled powder showed higher hardness. The microstructure of the as quenched specimens fabricated by sintering using mixed and milled powder almost are same, but the hardness of as quenched specimen fabricated by using mixed powder increased due to solution hardening of Nb in Ti matrix. The aging effect of these specimens on microstructural change and hardening is not prominent.
Cu , Mg을 함유한 Al-Li 합금의 기계적 성질과 전기저항 변화에 미치는 기본 및 추가 강화상들의 역할
정동석,송기호,우기도 ( D . S . Chung,K . H . Song,K . D . Woo ) 한국열처리공학회 1994 熱處理工學會誌 Vol.7 No.2
Roles of fundamental and additional hardening precipitates on the changes of mechanical properties and electrical resistivity during precipitation decomposition in binary Al-Li, ternaty Al-Lieu and multi-Li-Cu-Mg-Zr alloys have been investigated by the detailed measurement of electrical resistivity, hardness and tensile strength and the observation of transmission electron micrographs. Peek hardness and tensile strength in multi-component Al-Lieu-Mg-Zr Alloy had higher than that of the other alloys and the results of measurement of hardness, strength and electrical resistivity in each alloys aged at 90 and 190℃ precipitation behaviors and mechanical properties in binary, ternary and multi component Al-Li alloys were contributed to the δ`, precursory phase of δ`, T₁, G.P.B. zone and S`phases, respectively.
송기호,정동석,우기도 ( K . H . Song,T . S . Cheong,K . D . Woo ) 한국열처리공학회 1992 熱處理工學會誌 Vol.5 No.4
A study of the precipitation process of Al-Li binary alloy at low ageing temperature has been carried by electrical resistivity measurement. Two types of G.P. zones were formed during ageing at low temperature. G.P.(1) zone and G.P.(2) zone have been formed primarily at ageing temperature below 60℃ and at ageing temperature range of 80℃ to 100℃, respectively. Therefore the precipitation process of Al-Li binary alloy was as follows ; G.P.(1) zone→G.P.(2) zone→δ`→δ G.P.(1) zone might be affected by excess vacancies, but G.P.(2) zone might be affected by secondary defects, clusters and Li-vacancy pairs. The activation energy for formation of G.P.(2) zone is 0.87eV. It is lower than that of Al-Cu alloy.
스테인레스 430 소재의 전처리에 따른 고온 산화거동에 관한 연구
문민석(MinSeok Moon),우기도(KeeDo Woo),송준혁(JoonHyuk Song),오제하(JeHa Oh),강신재(ShinJae Kang) 한국자동차공학회 2009 한국자동차공학회 지부 학술대회 논문집 Vol.2009 No.10
Solid Oxide Fuel Cell (SOFCs) was high temperature operating Fuel cell system. Normally, this system operating temperature is approximately at 800~ 1000C. Fuel cell's efficiency was related with operating temperature. Operating temperature is increased that fuel cell efficiency is increased. Generally, SOFC was used to Bipolar plate material that Ceramic material with doped on the surface. Because SOFC was exposed high temperature atmosphere, ceramic material has stratified properties at the high temperature. At recent times, SOFC investigated focus on reduced operating temperature, IT SOFC (operation temperature at 600~800C) and LT SOFC (operation temperature at 400~600C). The aim of this study, apply to 430 stainless steels with different surface pre-treatment 3types, As-polished, As-Received and Sand Blast on the surface and no thermal satisfied coating treatment on the surface. 430 materials was exposure in the box furnace, at 800C with high temperature oxidation environment. And it observed to oxidation behavior with different exposures time. Oxidation behavior was analysis by SEM, EDS and XRD inspection.
나주 복암리 유적 출토 단조박편의 미세조직을 통한 단야 공정 기술체계 연구
송정일 ( Jung Ii Song ),우기도 ( Kee Do Woo ) 대한금속재료학회 ( 구 대한금속학회 ) 2012 대한금속·재료학회지 Vol.50 No.8
The microstructure of a hammer scale excavated from the Bogam-ri was examined in an effort to understand the iron technologies applied in the manufacturing of an iron forging process technology. The microstructures of oxide layer in the hammer scale were found to have crucial information about the ancient iron forging process treatment. The microstructure observed in the hammer scale can be distinguished by the forging process. First, the microstructure of the oxide layer in the hammer scale created by the forging process is Wstite (FeO) in the form of leaves. Latterly, the microstructure of the Wustite (FeO) in the hammer scale is observed to be in the form of a flat shape formed by a repeating forging process.
중온용 SOFC 분리판에 적용하기 위한 스테인레스 304 소재의 전처리에 따른 고온 산화거동에 관한 연구
문민석(MinSeok Moon),우기도(KeeDo Woo),송준혁(JoonHyuk Song),김원태(WonTae Kim),오제하(JeHa Oh),강신재(ShinJae Kang) 한국자동차공학회 2008 한국자동차공학회 지부 학술대회 논문집 Vol.2008 No.11
Solid oxide fuel cells (SOFCs) have many attractive features for widespread applications for Generation system. Recently investigation for bipolar plate is focus on the Metallic bipolar plate. Solid Oxide Fuel Cell was operated to high temperature than other Fuel cell system, approximately at 800~1000C. Presently day was investigated reduced operation temperature at 600~800C, that is Intermediate temperature SOFC. Solid Oxide Fuel Cell has required of low cost and high-temperature corrosion resistance during the operation. In this case, apply to 304 stainless steels with different pre-surface treatment with no coating treatment on the surface, As-polished, As-Received and Sand Blast on the surface. And 304 was exposure to high temperature oxidation environment, in the box furnace at 800C, and review to oxidation behavior with each material during the different exposures time.(100hrs, 400hrs). Oxidation behavior was measured by SEM, EDS and XRD inspection.
반도체 공정을 고려한 유한요소해석에 의한 MEMS 압전 작동기의 동특성 해석
김동운(Dong Woohn Kim),송종형(Jonghyeong Song),안승도(Seungdo An),우기석(Kisuk Woo) 한국소음진동공학회 2013 한국소음진동공학회 학술대회논문집 Vol.2013 No.4
For the purpose of rapid development and superior design quality assurance, sophisticated finite element model for SOM(Spatial Optical Modulator) piezo actuator of MOEMS device has been developed and evaluated for the accuracy of dynamics and residual stress analysis. Parametric finite element model is constructed using ANSYS APDL language to increase the design and analysis performance. Geometric dimensions, mechanical material properties for each thin film layer are input parameters of FE model and residual stresses in all thin film layers are simulated by thermal expansion method with psedu process temperature. 6<SUP>th</SUP> mask design samples are manufactured and 1<SUP>st</SUP> natural frequency and 10V PZT driving displacement are measured with LDV. The results of experiment are compared with those of the simulation and validate the good agreement in 1<SUP>st</SUP> natural frequency within 5% error. But large error over 30% occurred in 10V PZT driving displacement because of insufficient PZT constant d31 measurement technology.
1999년도 한국 신생아외과 현황 -대한소아외과학회 회원대상 전국조사(제 2 차)-
김우기,김상윤,김신곤,김인구,김재천,김현학,박귀원,박우현,송영택,오수명,유수영,이두선,이명덕,이성철,이석구,서정민,정상영,정성은,정을삼,정풍만,Kim, W.K.,Kim, S.Y.,Kim, S.K.,Kim, I.K.,Kim, J.C.,Kim, H.H.,Park, K.W.,Park, W.H.,Song, Y.T.,Oh, S.M.,Yoo, Y.S.,Lee, D.S 대한소아외과학회 2001 소아외과 Vol.7 No.1
To understand the current status of neonatal surgery in Korea, a survey was made among the 36 members of the Korean Association of Pediatric Surgeons. The response rate was 75 % (26 surgeons in 20 hospitals). Five hundred fifty three neonatal surgical patients treated in 1999 were analyzed. Regional numbers of patients were closely related to the regional population in most areas. Ano-rectal malformations (17 %), pyloric stenosis (16 %), Hirschsprung's disease (13 %), atresia/stenosis of the gut (11 %), esophageal atresia (8 %) were the most common anomalies treated. The majority of operations were done within the first week of life. Seventy one per cent of cases were major life threatening or so-called neonatal index cases. Over-all mortality was 8 per cent. Higher mortality was observed in patients with diaphragmatic hernia (26 %), gastro-intestinal perforation (18 %), NEC (18 %), and esophageal atresia(14 %). Higher mortality was observed in patients with extremely low birth weight (33%) and low birth weight (18 %). Associated anomalies were observed in 20 %. Prenatal ultrasound was performed in 36 per cent with sensitivity of 20 %. Result of this study was compared to the previous report (1994) and that of Japan (1998).
1994년도 한국신생아외과의 현황 - 대한소아외과학회 회원대상 전국조사 -
김우기,김상윤,김신곤,김인구,김재천,박귀원,박영식,박우현,박주섭,송영택,오수명,이두선,이명덕,이성철,장수일,정을삼,정풍만,주종수,최순옥,허영수,황의호,Kim, W.K.,Kim, S.Y.,Kim, S.K.,Kim, I.K.,Kim, J.C.,Park, K.W.,Park, Y.S.,Park, W.H.,Park, J.S.,Song, Y.T.,Oh, S.M.,Le 대한소아외과학회 1996 소아외과 Vol.2 No.1
To understand the current status of neonatal surgery in Korea, a survey was made among the 27 members of Korean Association of Pediatric Surgeons. Response rate among surgeons was 78 percent, eighteen hospitals participated in this study. Five hundred and three cases of neonatal surgical patients were analyzed. In Korea, about 50% of cases were treated at the hospital in the capital city area. Regional number of patients were closely related to the regional population. Imperforate anus(19%), atresia/stenosis of gut(12%), and Hirschsprung's diseases(12%) were sitting at the top in the list. Majority of operation was done within the first week of life, especially during the first 24 hour period. Eighty per cent was major or so called index cases. Mortality in so-called index cases was 17%. High mortality was observed in patients with diaphragmatic hernia(47%), gastrointestinal perforation(65%) and esophageal atresia(28%). Low birth weight babies showed higher mortality in gastrointestinal perforation, esophageal atresia and abdominal wall defect. These were compared to 1993 survey of Japanese Society of Pediatric Surgeons.
Hirschsprung's Disease의 진단과 치료 : 1992년도 현황 -대한소아외과학회 회원대상 선호도 설문조사-
유수영,김상윤,김우기,김인구,김재억,박귀원,박우현,박주섭,송영택,오수명,이두선,이명덕,이성철,장수일,정상영,정을삼,정풍만,주종수,최금자,최순옥,최승훈,허영수,황의호,Yeo, S.Y.,Kim, S.Y.,Kim, W.K.,Kim, I.K.,Kim, J.E.,Park, K.W.,Park, W.H.,Park, J.S.,Song, Y.T.,Oh, S.M.,Lee, 대한소아외과학회 1996 소아외과 Vol.2 No.1
This report present the result of the national survey of pediatric surgeons' preferences on diagnosis and treatment of Hirschsprung's disease(HD) carried out in 1993. The questionnaires were sent to twenty-seven members of the Korean Association of Pediatric Surgeons (KAPS) working in twenty-four institutions. The questionnaires were designed to determine the individual surgeon's preference for the methods of diagnosis and treatment of the disease. Twenty-three pediatric surgeons from twenty institutions returned completed forms. The total number of patients diagnosed with HD in 1992 was 190 in this group. The estimated incidence of HD was 1/3,900. The most important symptom was delayed meconium passing and the most preferred diagnostic procedure was barium study. Anorectal manometric examination was carried out by 13 pediatric surgeons and 19 confirmed the diagnosis before operation by rectal biopsy, 12 with full-thickness biopsy and 7 with suction. Frozen section biopsy during operation was done by 22 surgeons. Eight surgeons did one stage operation if the age of the patient is suitable. Definitive operation was usually done at the age of 6 to 11 months. The most preferred operation was Duhamel procedure done by 19. Enterocolitis was the most serious complication of HD. Most of patients had normal continence within 6 to 12 months after operation. The follow-up period was less than 6 years in 16 surgeons. The results were presented at the 9th annual meeting of KAPS in June of 1993. This is the first national survey of HD and it can provide guidelines of diagnosis and treatment of Hirschprung's disease even though it is not a detailed study of patient data.