연구원 활동 : 발표논문요약 < 재료공학분야 >

류준욱,임대순 고려대학교 공학기술연구소 1995 생산기술연구소보 Vol.2 No.-

복합 레진 세멘트의 두께에 따른 라미네이트용 도재와의 결합강도

류준욱 慶北大學校 齒科大學 1994 慶北齒大論文集 Vol.11 No.2

라미네이트용 도재와 복합레진 세멘트의 두께에 따른 전단결합강도를 알아보기위해, 발거된 48개의 소구치를 법랑-백아질 경계선상에서 치아장축에 수직되게 절단한 후 치관을 아크릴릭 레진에 묻고 법랑질면을 편평하게 노출시켰고 라미네이트용 도재를 통법에 따라 소성하여 편평하게 하였다. 그후 레진세면트로 Micrometer를 이용하여 Ⅰ군에서 30μm, Ⅱ군에서 60μm, Ⅲ군에서 90μm, Ⅳ군에서 120μm,의 두께가 되도록 법랑질면에 도재시편을 합착하였다. 인스트론 만능시험기에 Holding jig를 이용하여 시편을 거상하고 분당 0.5mm cross head speed로 전단결합강도를 측정하고 시편의 파단면을 주사전자현미경을 사용해서 관찰한 결과 다음과 같은 결과를 얻었다. . 각 군의 평균전단결합강도는 Ⅲ군에서 18.85±3.84Mpa, Ⅳ군에서 16.82±2.53Mpa, Ⅱ군에서 15.30±2.58Mpa, Ⅰ군에서 12.44±3.52Mpa의 순으로 나타났다. . Ⅲ군은 Ⅰ군과 Ⅱ군에 비해 통계적으로 유의성 있는 차이를 나타내었다(p<0.01) The purpose of this study was to evaluate the shear bond strength of composite resin cement bonded to porcelain laminates with various cement film thickness. Fouty-eight recently extracted, intact premolars were used and stored in a physiologic saline solution from the time of extraction. The crown of each tooth was cut with a water-cooled diamond disk at the cemento-enamel junction. Then, the crown parts of teeth were embedded with acrylic resin and enamel surfaces were exposed flat. Laminate porcelain(Ceramco Ⅱ Veneer porcelain, Ceramco Inc., U.S.A.) was condensed in metal ring and baked according to the manufacturer's recommendations. Each surface was flatted on the diamond disk and smoothed with No.1200 grit paper. All porcelain specimens were sandblasted and ultrasonically cleaned in distilled water for 3 minutes. Then, all porcelain specimen were etched with 8% hydrofluoric acid for 5 minutes. Fourty-eight specimens were then randomly divided into four groups and bonded with composite resin cement(Choice Porcelain Veneer System, Bisco Inc., U.S.A.). The film thickness of each group were:group Ⅰ, 30μm; group Ⅱ, 60μm;group Ⅲ, 90μm;group Ⅳ, 120μm. The combined length of two specimens were meansured with micrometer apparatus prior to bonding, and the masking tape with 3.5mm hole was attached to each specimen. Composite resin cement was mixed according to the manufacturer's directions. Excess resin cement was applied to the test end of tooth specimen. Micrometer device secured the specimens in a rigid position during bonding and assured a controlled film thickness for each group. The failure loads of the specimens were measured by Instron universal testing machine. The mean values of failure loads for the groups were statistically compared by Duncan's multiple range test. The results were as follows; 1. Mean shear bond strengths of each group were 18.85±3.84Mpa in group Ⅲ, 16.82±2.53Mpa in group Ⅳ, 15.30±2.58Mpa in group Ⅱ, 12.44±3.52Mpa in group Ⅰ. 2. There was a statistically significant difference between group Ⅲ & group Ⅰ and Ⅱ(p<0.05).

레진 세멘트와 포스트의 길이가 근관 치료된 치아의 포스트 유지력에 미치는 영향

류준욱,권정애 慶北大學校 齒科大學 1993 慶北齒大論文集 Vol.10 No.2

근관치료를 한 치아에 포스트를 해야할 경우 세멘트의 종류나 세멘트되는 포스트 길이가 포스트의 유지에 어떠한 영향을 주는지 알아보기 위하여, 하악 절치 30개를 이용하여 법랑-백악질 경계 선상에서 치아장축에 수직되게 절단한 후 근관치료 및 근관충전을 하였다. 기성품의 parallel Para-post를 샌드브라스팅하여 Ⅰ군에서는 깊이 4mm에 Z.P.C., Ⅱ군에서는 깊이 8mm에 Z.P.C., Ⅲ군에서는 깊이 4mm에 All-Bond, Ⅳ군에서는 깊이 8mm에 All-Bond로 세멘트 하였다. 3일이 경과후 인스트론 만능시험기에 retention jig를 사용하여 포스트가 세멘트된 시편을 거상하고 cross head speed 1mm/min으로 인장력을 가하여 유지력을 측정하고 포스트 공간 형성 후, All-Echant처리 후 파절된 Ⅲ군과 Ⅳ군의 치근내면 및 포스트와 레진의 접합면을 주사전자현미경을 사용해서 관찰하여 다음과 같은 결과를 얻었다. 1. 각 군의 평균 파단 하중은 Ⅳ군에서 23.80±4.17kg, Ⅱ군에서 17.99±5.5kg, Ⅲ군에서 16.68±5.13kg, 그리고 Ⅰ군에서 10.20±4.08kg의 순으로 나타났다. 2. Z.P.C.를 사용한 Ⅰ군과 Ⅱ군 사이에는 Ⅱ군이 높게 나타났으며(P<0.05), All-Bond를 사용한 Ⅲ군과 Ⅳ군 사이에도 Ⅳ군이 높게 나타났다(P<0.05) 3. 포스트의 길이에서 4mm의 Ⅰ군과 Ⅲ군 사이에는 Ⅲ군이 높게 나타났고(P<0.05), 8mm의 Ⅱ군과 Ⅳ군 사이에는 Ⅳ군이 높게 나타났다(P<0.05) 4. 주사전자현미경 관찰에서 All-Bond를 사용한 군에서 치경부 부위에 많은 레진 tag를 관찰할 수 있었으나 치근단 부위로 갈수록 레진 tag를 관찰할 수 없었다. The purpose of this study was to evaluate the effect of various cements & the length of post to retention of post in the endodontically treated teeth. Thirty three mandibular incisors were used. The coronal portion of the teeth were removed at the cemento-enamel junction. Every tooth was endodontically treated. After 2 days, post space preparation was made with Para-post drill(P-42-1) to depth of 4mm & 8mm. The teeth were divided into four groups. Group Ⅰ was composed of 8 mandibular incisors and posts were cemented with zinc phosphate cements to depth of 4mm. Group Ⅱ was composed of 8 mandibular incisors and posts were cemented with zinc phosphate cements to depth of 8mm. Group Ⅲ was composed of 8 mandibular incisors and posts were cemented with All-Bond to depth of 4mm. Group Ⅳ was composed of 8 mandibular incisors and posts were cemented with All-Bond to depth of 8mm. Special retention jig was made. After 3 days,teeth with cemented post were mounted on retention jig and failure load of the specimens were measured by an Instron Universal Testing Machine. And,scanning electron microscopy was examined on the internal surface of root after post space preparation, treatment of All-echant, internal surface of fractured group Ⅲ & group Ⅳ, and interfacial surface of post & resin. The results were as follows. 1. Mean failure loads of each group was 23.80±4.17kg in group Ⅳ,17.99±5.5kg in group Ⅱ,16.68±5.13kg in group Ⅲ,and followed by 10.20±4.08kg in group Ⅰ. 2. There was a statistically significant difference between group Ⅰ & group Ⅱ and between group Ⅲ & group Ⅳ(P<0.05). The score of group Ⅰ was higher than group Ⅱ(P<0.05). And,that of group Ⅳ was higher than group Ⅲ(P<0.05). 3. In post length, group Ⅲ was statistically higher than group Ⅰ and group Ⅳ was statistically higher than group Ⅱ(P<0.05). 4. In examination of scanning electron microscopy, groups Ⅳ used All-Bond was examed many resin tags in cervical portion, but there was no resin tag in apical portion and group Ⅲ was examed many rsin tags. J. Kyungpook Nat. Univ. Sch Dent Vol10, NO.2,

엔진유의 물성이 자동차연비에 미치는 영향

문우식(W.S.Moon),류준욱(J.W.Ryoo),조연근(Y.G.Cho),정홍석(H.S.Chung),정범서(B.S.Cheong) 한국자동차공학회 1998 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1998 No.5_1

Automotive fuel consumptions with different engine oils are determined according to the EPA FTP-75 method in this study. The results of fuel economy are discussed correlating with the properties of engine oils. To improve automotive fuel economy with engine oils, it is necessary to use VHVI base oils in formulating engine oil. The engine oils formulated with a VHVI base oil has better viscometric properties, resulting in better fuel economy. The temporary viscosity loss at 150℃ also affects automotive fuel economy.<br/>

Glutathione S-transferases (GSTM1, GSTT1 and GSTP1) and N-acetyltransferase 2 Polymorphisms and the Risk of Gastric Cancer

홍수형,김정완,김호각,박인규,류준욱,이창형,손윤경,이종영,Hong, Su-Hyung,Kim, Jung-Wan,Kim, Ho-Gak,Park, In-Kyu,Ryoo, Jun-Wook,Lee, Chang-Hyeong,Sohn, Yoon-Kyung,Lee, Jong-Young The Korean Society for Preventive Medicine 2006 예방의학회지 Vol.39 No.2

Objectives : Polymorphisms of genes from glutathione Stransferases (GSTs) and N-acetyltransferase 2 (NAT2) have been associated with increased susceptibility to various cancers. Previous results showed that East Asians such as Koreans, Japanese and Chinese have a much higher frequency of the GSTM1 and GSTT1 null genotypes and NAT2 rapid acetylator type. Therefore, we investigated the association between the polymorphic types of GSTs (GSTM1, GSTT1, GSTP1) and NAT2 and the incidence of gastric cancer which is one of the most prevalent cancers among the East Asians. Methods : It was performed in a case-control study consisting of 238 healthy subjects and 108 cancer patients (54 distal and 54 proximal carcinomas). We also evaluated the association between GSTs and NAT2 and the risk factors for gastric cancer such as alcohol consumption, smoking, H. pylori infection, family history of gastric cancer, and tumor location. Results : In our study, the percentage of cases whose hometown was rural was higher than those of controls (odds ratio (OR) =2.88; 95% CI=1.72-4.76), and the frequency of the lower socio-economic status increased significantly in patients (OR=2.53; 95% CI=1.59-4.02). There was no significant difference in the GST polymorphic types between the cases and controls. However, NAT2 rapid or intermediate acetylator types were frequently detected in the cases with family history of gastric cancer (OR=1.92; 95% CI=1.79-26.0). Conclusions : These results suggest that the hometown and socio-economic status are important environmental factors for gastric carcinogenesis, and NAT2 polymorphic types could be associated with familial gastric carcinoma.