(A) study of tissue reactions to calcium phosphate ceramics on subperiosteal implants in dogs

치의학과/석사[한글] 치과 이식용 calcium phosphate ceramics제재를 조성과 거대기공 유무에 따라 porous hydroxyapapatite, dense hydroxyapatite, porous tricalcium phosphate 및 dense tricalcium phosphate로 분류하여 실험군으로, 외과용 Vitallium(Howmedica Inc., New York, N.Y .)을 비교군으로 하여 골막하 이식체로서의 적합성을 조사하기 위하여 성견 5마리의 상악 협점막 골막하에 이식한 후, 주위조직에 미치는 반응을 3일, 1주, 2주, 4주 및 8주째에 관찰하여 다음과 같은 결론을 얻었다. 1. 모든 실험군과 비교군에서 3일째에는 심한 급만성 염증세포의 침윤이, 1주째에는 염증소견의 현저한 감소와 결체조직의 피개 및 치조골 흡수소견이 관찰되었다. 2. 비교군에서는 2주째에 두꺼운 섬유성 막의 피개와 급, 만성염증세포의 침윤 및 골흡수 소견이 보였으며, 4주째에는 섬유성 막의 피개와 골수강 내의 조골세포의 침윤 및 골흡수 소견이, 8주째에는 섬유성 막의 피개만 관찰되었다. 3. Porous hydroxyapatite와 dense hydroxyapatite군에서, 2주와 4주째에는 염증소견없이 얇은 섬유성 막의 피개가, porous hydroxyapatite군에서는 4주째에 탐식세포의 침윤과 골흡수 소견의 감소도 보였으며, 두군 모두에서 8주째에는 탐식세포 및 염증세포와 조골세포 및 파골세포의 침윤이 관찰되었다. 4. 2주째에서 porous tricalcium phosphate군에는 염증소견이 없었고, dense tricalcium phosphate군에는 탐식세포와 만성염증세포의 침윤이 보였으며, 두군 모두에서 4주째에는 탐식세포의 침윤과 골흡수 소견이, 8주째에는 탐식세포 및 염증세포와 조골세포 및 파골세포의 침윤이 관찰되었다. A STUDY OF TISSUE REACTIONS TO CALCIUM PHOSPHATE CERAMICS ON SUBPERIOSTEAL IMPLANTS IN DOGS Soon Ho Hong, D.D.S. Department of Dental Science, The Graduate School, Yonsei University (Directed by Prof. Ho Yong Lee, D.D.S., M.S.D., Ph.D.) The purpose of this study was to observe the tissue reactions to four experimental groups of calcium phoshpate ceramics, which are porous hydroxyapatite, dense hydroxyapatite, porous tricalcium phosphate and dense tricalcium phosphate implants, and to the control group of surgical grade Vitallium(Howmedica Inc., New York, N.Y.) after 3 days, 1 week, 2 weeks, 4 weeks and 8 weeks from subperiosteal implantation on maxillary buccal mucosa of 5 dogs. The results were obtained as follows : 1. In all experimental and control groups, marked infiltration of acute and chronic inflammatory cells were observed after 3 days, and resorption of alveolar bone, covering of connective tissue with marked decrease in inflammatory reaction were observed after 1 week. 2. In control group, the following were observed covering of the thick fibrous tissue wall and infiltration of acute and chronic inflammatory cells as well as resorption of alveolar bone after 2 weeks, and covering of fibrous tissue wall, infiltration of osteoblasts and resorption of alveolar bone after 4 weeks, but after 8 weeks only the covering of the fibrous tissue wall. 3. After 2 and 4 weeks, covering of thin fibrous tissue wall without any inflammatory reaction were observed from porous hydroxyapatite and dense hydroxyapatite groups, with additional infiltration of macrophage and resorption of alveolar bone from dense hydroxyapatite groups after 4 weeks, and after 8 weeks, infiltration of macrophages and inflammatory cells as well as osteoblasts and osteoclasts were observed in both groups. 4. After 2 weeks no inflammatory reaction from porous tricalcium phosphate group, and infiltration of macrophage and chronic inflammatory cells from dense tricalcium phosphate group, but after 4 weeks resorption of alveolar bone with infiltration of macrophages, and after 8 weeks, infiltration of macrophages and inflammatory cells as well as osteoblasts and osteoclasts were observed in both groups. [영문] The purpose of this study was to observe the tissue reactions to four experimental groups of calcium phoshpate ceramics, which are porous hydroxyapatite, dense hydroxyapatite, porous tricalcium phosphate and dense tricalcium phosphate implants, and to the control group of surgical grade Vitallium(Howmedica Inc., New York, N.Y.) after 3 days, 1 week, 2 weeks, 4 weeks and 8 weeks from subperiosteal implantation on maxillary buccal mucosa of 5 dogs. The results were obtained as follows : 1. In all experimental and control groups, marked infiltration of acute and chronic inflammatory cells were observed after 3 days, and resorption of alveolar bone, covering of connective tissue with marked decrease in inflammatory reaction were observed after 1 week. 2. In control group, the following were observed covering of the thick fibrous tissue wall and infiltration of acute and chronic inflammatory cells as well as resorption of alveolar bone after 2 weeks, and covering of fibrous tissue wall, infiltration of osteoblasts and resorption of alveolar bone after 4 weeks, but after 8 weeks only the covering of the fibrous tissue wall. 3. After 2 and 4 weeks, covering of thin fibrous tissue wall without any inflammatory reaction were observed from porous hydroxyapatite and dense hydroxyapatite groups, with additional infiltration of macrophage and resorption of alveolar bone from dense hydroxyapatite groups after 4 weeks, and after 8 weeks, infiltration of macrophages and inflammatory cells as well as osteoblasts and osteoclasts were observed in both groups. 4. After 2 weeks no inflammatory reaction from porous tricalcium phosphate group, and infiltration of macrophage and chronic inflammatory cells from dense tricalcium phosphate group, but after 4 weeks resorption of alveolar bone with infiltration of macrophages, and after 8 weeks, infiltration of macrophages and inflammatory cells as well as osteoblasts and osteoclasts were observed in both groups.restrictio

(A) study of tissue reactions to Pt-Co magnets embedded in hydroxyapatite ceramic implants in the alveolar bone of dogs

치의학과/박사[한글] 저자는 Pt-Co자석이 매몰된 hydroxyapatite ceramics 이식체의 의치 유지력 향상을 위한 임상적 응용가능성을 관찰하기 취하여 골과 유착되는 hydroxyapatite ceramics만으로 된 이식체를 대조군, 이식체에 자석이 매몰된 것을 실험군 Ⅰ, 이식후1 2주부터 보철물에 부착된 자석과의 상호인력 (attractive force)에 의하여 6주간 기능을 받은 이식체를 실험군Ⅱ로 하여, 각각의 시편이 이식된 5마리의 성견 치조골에서 주위조직 반응을 광학 현미경적 및 형광 현미경적으로 검경하여 다음과 같은 결론을 얻었다. 1. 대조군의 상단면은 섬유성 결체조직에 의한 피복과 일부에서는 골양조직의 형성을 보였고, 측면 및 하단면은 골조직에 의한 유착을 보였으며 국소적으로는 결체조직이 잔존되어 있었다. 2. 실험군 Ⅰ, Ⅱ에서 상단면은 섬유성 결체조직의 피복과 신생골 형성이 있고, 측면 및 하단면은 대조군과 유사한 소견을 보였다. 3. 대조군, 실험군Ⅰ, Ⅱ 모두에서 이물반응은 관찰할 수 없었다. 4. 형광 현미경적 소견상 대조군의 상단면에서 미만성의 대(band)상 또는 점(dot)상 형광과, 측면에서 동심원상의 대상 형광, 그리고 하단면에서는 감소된 대상의 형광을 보였다. 5. 형광 현미경적 소견상 실험군 Ⅰ, Ⅱ에서 상단면에 대상 및 점상형광과, 측면에서는 동심원상의 형광대를 하단면에서는 측면에 비해 현저히 감소된 형광을 보여 대조군과 유사하였다. A STUDY OF TISSUE REACTI0NS TO Pt-Co MAGNETS EMBEDDED IN HYDROXYAPATITE CERAMIC IMPLANTS IN THE ALVEOLAR BONE OF DOGS Soon Ho Hong, D.D.S., M.S.D. Department of Dental Science, The Graduate School, Yonsei University. (Directed by Professor Ho Yong Lee, D.D.S., M.S.D., Ph. D.) The purpose of this study is to evaluate the clinical feasibility of Pt-Co magnets embedded in hydroxyapatite ceramic implants for the retention of dentures. The auther investigated the tissue reactions to three groups of implants in the alveolar bone of each dog. The hydroxyapatite ceramics without magnets were the control group. The Pt-Co magnets embedded in hydroxyapatite ceramics were experimental group Ⅰ. The Pt-Co magnets embedded in hydroxyapatite ceramics (as experimental group Ⅱ) attracted the magnets attached prostheses which had been fixed until the sacrifice of the dogs after the 12th week after implantation. 5 mongrel dogs (weighing about 15kg) were used in this study. The tissue reactions of the three groups were observed under light microscopic and fluorescence microscopic examination. The results were obtained as follows: 1. In the control group, fibrous and some osteoid tissues formed on the upper surface, and bone trabeculae were fused to the lateral and basal surface. Fibrous tissue appeared on some parts of the basal surface. 2. In experimental group Ⅰ, Ⅱ, fibrous encapsulation and new bone formation appeared on upper surface and findings on lateral and basal surfaces were similar to those in the control group. 3. In control and experimental group Ⅰ, Ⅱ, no foreign body reactions were observed. 4. On the fluorescene microscopic examination in the control group, diffuse fluorescent bands and dots on the upper surface, and concentric fluorescent bands on the lateral surface, as well as diminished fluorescent granules and bands on the basal surface were observed. 5. On the fluorescence microscopic examination in experimental group Ⅰ, Ⅱ, their findings were similar to those in the control group. [영문] The purpose of this study is to evaluate the clinical feasibility of Pt-Co magnets embedded in hydroxyapatite ceramic implants for the retention of dentures. The auther investigated the tissue reactions to three groups of implants in the alveolar bone of each dog. The hydroxyapatite ceramics without magnets were the control group. The Pt-Co magnets embedded in hydroxyapatite ceramics were experimental group Ⅰ. The Pt-Co magnets embedded in hydroxyapatite ceramics (as experimental group Ⅱ) attracted the magnets attached prostheses which had been fixed until the sacrifice of the dogs after the 12th week after implantation. 5 mongrel dogs (weighing about 15kg) were used in this study. The tissue reactions of the three groups were observed under light microscopic and fluorescence microscopic examination. The results were obtained as follows: 1. In the control group, fibrous and some osteoid tissues formed on the upper surface, and bone trabeculae were fused to the lateral and basal surface. Fibrous tissue appeared on some parts of the basal surface. 2. In experimental group Ⅰ, Ⅱ, fibrous encapsulation and new bone formation appeared on upper surface and findings on lateral and basal surfaces were similar to those in the control group. 3. In control and experimental group Ⅰ, Ⅱ, no foreign body reactions were observed. 4. On the fluorescene microscopic examination in the control group, diffuse fluorescent bands and dots on the upper surface, and concentric fluorescent bands on the lateral surface, as well as diminished fluorescent granules and bands on the basal surface were observed. 5. On the fluorescence microscopic examination in experimental group Ⅰ, Ⅱ, their findings were similar to those in the control group.restrictio

Automatic control of growth environment for plant factory

학위논문(박사)--서울大學校 大學院 :農工學科 農業機械專攻,1995.Docto

Hong, Soon-Ho

학위논문(박사)--아주대학교 일반대학원 :건설교통공학과,2008. 8본 연구에서는 보편적으로 국내 교량 시공분야에서 빈번히 시공되는 교량 형식인 Steel BOX 거더교, PC BOX 거더교에 대해 탄성받침과 고감쇠 고무 받침을 적용하여 지진시 거동에 대한 분석하였다. 고감쇠 고무 받침에 대한 역학적 거동 특성을 알아보고 또한 감쇠효과 및 이력특성에 대한 고찰을 하였다. 고감쇠 고무받침을 적용할 경우 지진시 변위를 감소시키고 교각 기둥에 작용하는 모멘트와 전단력을 감소시켜 경제적인 교량설계가 이루어지는데 기여하는 효과가 큰 것으로 분석되었고 연구내용을 요약하면 다음과 같다. 1) 지진격리장치의 설계 교량 받침의 재료로 사용되는 고무에 대한 거동특성을 조사하여 기술하고 기존의 내진설계시 많이 사용되는 탄성받침의 특성을 고찰하며 설계방법을 소개하였다. 탄성받침을 재료적으로 개선하여 감쇠효과를 갖도록 최근 국내에서 개발되어 상용화 준비중인 고감쇠 고무받침의 성능시험과정과 역학적 거동 특성을 고찰하였다. 또한, 교량분야에서 주로 연구된 지진격리장치에 대한 원리 및 거동 특성을 소개하고 지진격리설계에 대한 국내설계기준을 기술하였고 지진해석에 필요한 경계 비선형 해석 기법에 관한 이론적 배경을 설명하였다. 2) 수치해석 수치해석을 위해 대상교량에 대해 교량받침별(탄성받침, 10% 감쇠성능을 가진 HDRB, 15% 감쇠성능을 가진 HDRB, 20% 감쇠성능을 가진 HDRB), 교각 높이별(10m, 20m, 30m, 40m, 50m, 60m)로 지진해석 모델을 구축하고 비선형 시간이력해석을 수행하였다. 각각의 경우별로 교량 받침에 작용하는 수평전단력, 수평변위와 교각의 기둥에 작용하는 단면력을 비교 분석하였다. 지진격리장치인 고감쇠 고무받침을 적용한 경우 받침변위 제어 및 교각 기둥 단면력 감소에 매우 효과적인 것으로 분석되었다. 3) 지진해석결과를 반영한 교량설계 수치해석에서 구한 받침 전단력을 기초로 교량형식별, 받침 종류별로 용량검토를 수행하여 받침 규격을 재산정하였고, 받침변위 응답을 고려하여 지진시 거더간 충돌을 방지하기 위한 여유거리를 산정하고 이를 신축이음 규격 결정시 고려하였다. 교량별로 지진해석에서 구한 단면력과 상시 조건에서의 작용하중을 기초로 P-M상관 분석을 하여 교량 형식별, 교각 높이별로 적정한 교각 기둥의 직경을 재산정하였다. 결과적으로 고감쇠 고무받침을 적용한 경우 신축이음 장치의 규격을 현저히 줄일 수 있었다. 또한 기둥직경이 크게 줄어 탄성받침 적용시에 비해 소성설계 적용빈도 및 중공형 교각 적용빈도를 크게 줄일 수 있었다. 4) 경제성 분석 및 가치 평가 최근의 물가자료를 바탕으로 교량 형식별, 교각 높이별로 재산정한 교각제원과 지진시 받침 전단력 및 받침 변위를 고려하여 받침의 용량과 신축이음 규격을 재산정하였다. 또한, 교량하부 공사비를 산출하고 이를 근거로 교량형식별로 교각 높이를 고려한 생애주기비용을 구하는 경제성 분석을 실시하였다. 생애주기비용을 바탕으로 경제성, 하부 조망권에서의 경관성, 시공성, 유지관리 효율성, 구조안전성, 기능성 및 편의성을 고려한 가치분석을 수행하였다. 5) 연구결과 탄성받침을 고감쇠 고무받침으로 대체할 경우 신축이음의 규격이 작아져서 주행성 및 유지관리에서 유리하고, 교각 기둥의 직경이 축소되어 교량의 균형미가 우수하고 시공이 양호하며, 특히 하부 공간 활용성 측면에서 많은 이점을 제공한다. 결국 가치공학 측면에서 볼 때 비용은 절감하며 가치를 향상시키는 가치혁신형 유형이다.1. 서론 = 1 1.1 연구배경 및 목적 = 1 1.2 연구동향 = 4 1.3 연구범위 및 방법 = 5 2. 지진격리장치의 설계 = 10 2.1 고무재료의 특징 = 10 2.2 탄성받침의 특성 = 11 2.3 고감쇠 고무받침의 특성 및 설계 = 12 2.4 고감쇠 고무받침의 특성 시험 = 15 2.4.1 고무받침 시험의 방법 및 절차 = 15 2.4.2 시제품의 특성 시험결과 = 15 2.5 구조물의 내진설계와 지진격리설계 = 19 2.5.1 개요 = 19 2.5.2 지진격리시스템의 원리 = 19 2.5.3 지진격리시스템의 종류 = 21 2.5.4 지진격리장치의 경계비선형 시간이력해석 = 32 2.6 지진격리교량에 대한 국내설계기준 = 36 3. 가치공학과 생애주기비용 = 39 3.1 생애주기비용의 정의 = 39 3.2 가치공학의 정의 = 39 3.3 생애주기비용 분석 기법 = 39 3.4 생애주기비용의 구성 = 40 3.4.1 초기투자비용 = 40 3.4.2 유지관리비용 = 41 3.4.3 해체 및 폐기비용 = 47 3.5 분석기간 = 49 3.6 할인율 = 49 3.7 화폐의 시간가치 측정방법 = 51 3.8 가치공학(VE)의 방법론 = 51 3.9 계층분석법(AHP 기법) = 54 3.9.1 쌍비교행렬의 구성 = 54 3.9.2 고유벡터법 = 56 3.9.3 일관성측정 = 58 3.10 성능 평가항목 선정 = 59 3.10.1 경제성 = 59 3.10.2 경관성 = 59 3.10.3 안전성 = 60 3.10.4 기능성 = 60 3.10.5 유지관리 효율성 = 60 3.10.6 시공성 = 61 3.10.7 편의성 = 61 4. 수치해석 = 62 4.1 수치해석 대상 교량 선정 = 62 4.1.1 ST. BOX 거더교 현황 = 62 4.1.2 PC. BOX 거더교 현황 = 64 4.2 설계조건 및 받침제원 = 65 4.3 유한요소모델링 = 68 4.3.1 ST. BOX 거더교 모델링 = 68 4.3.2 PC. BOX 거더교 모델링 = 69 4.4 해석 절차 및 방법 = 71 4.5 수치해석결과 = 72 4.5.1 시간이력해석결과 = 72 4.5.2 받침전단력 응답 = 75 4.5.3 받침변위 응답 = 83 4.5.4 기둥모멘트 응답 = 91 5. 지진해석결과를 반영한 교량설계 = 95 5.1 받침규격 재산정 = 95 5.2 신축이음 규격 재산정 = 98 5.3 교각 기둥 직경 재산정 = 110 6. 생애주기비용(LCC) 산출 = 118 6.1 ST. BOX 거더교 = 118 6.1.1 초기공사비 = 118 6.1.2 유지관리비 = 122 6.1.3 해체 및 폐기물 처리비 = 123 6.1.4 생애주기비용(LCC) = 124 6.2 PC. BOX 거더교 = 130 6.2.1 초기공사비 = 130 6.2.2 유지관리비 = 134 6.2.3 해체 및 폐기물 처리비 = 135 6.2.4 생애주기비용(LCC) = 136 7. 가치 평가 = 142 7.1 경제성 평가 = 142 7.2 대안의 속성평가 = 143 7.3 쌍비교 및 중요도 산정 = 143 7.3.1. 쌍비교행렬 구성 = 143 7.3.2 일관성 검토 = 144 7.4 대안 선정 = 145 8. 결론 = 155 참고문헌 = 157 ABSTRACT = 162 부록 = 165 감사의 글 = 211MasterIn this study it applied Elastic Rubber Bearing(RB) and High-Damping Rubber Bearing(HDRB) in about Steel BOX girder bridges which area bridge type which is constructed frequently from domestic bridge constructive field and PC BOX girder bridges when earthquake this coming in about conduct, it analyzed. HDRB it examined an mechanical conduct quality in about RB and also it investigated in about damping effect and historical characteristic. HDRB thecase which willapply RB it decreases the displacement which operate to the piercolumn a momentand the shearforce which and it decreases the bridge plan which is economic becomes accomplished to be analyzed with the fact that the effect which it contributes is big when the study contents it summarizes, as followings. 1)Design of seismic isolation device It investigated a conduct quality in about the rubber which is used with the material of the bridge support and it described and when doing the seismic design of existing, are used plentifully RB qualities which a plan method and it investigated it introduced. RB material in order to have a damping effect, it was developed recently from domestic and HDRB performance test process which is in the process of commercial business preparing and an mechanical conduct quality it investigated. Also, it introduced a principle and a conduct quality to about the seismic isolation device which is mainly researched from bridge field a domestic design size in about seismic design and it described. It explained a theoretical background in about the guard nonlinear boundary analysis technique which is necessary to an seismic analysis. It respected a numerical analysis and in about the objective bridge at bridge support by and pier height by to construct the seismic analysis model it accomplished nonlinear time history analysis technique. 2)Numerical analysis It respects a numerical analysis at bridge support by (RB ,10% damping ratio HDRB, 15% damping ratio HDRB, 20% damping ratio HDRB) and pier height by (10m, 20m, 30m, 40m, 50m and 60m)it constructed the seismic design model in about the objective bridge and it accomplished a nonlinear time history analysis. In the case support displacement control which applies HDRB where it is an seismic isolation device and pier column sectional power decrement very it was analyzed with the fact that it is effective. 3)Bridge design which reflects an seismic analysis result The bearing shear force which buys from numerical analysis with foundation it investigated a dosage in bridge type and by and bearing type by property really it did a bearing size. It considers a bearing displacement answer back and when earthquake this coming, a girder between collision it prevents the superstructure to do the surplus distance for, this when deciding a size of expansion joint, it considered. Action load from the section power which with the bridge by buys from seismic analysis and regular condition it analyzed P-M interrelation with foundation and diameterthe piercolumn which is proper at bridge type by and pier height by property really. The possibility of reducing the size of the case expansion joint which resultantly applies HDRB remarkably it was. Also, the column diameter will decrease on a large scale and when RB applying, it will compare and the possibility which a laughter plan application frequency and a hollow type pier application frequency on a large scale it will reduce it was. 4)Analysis of economy and value evaluation Sensitive data of recent times bridge type by, when property really one pier man power and earthquake this coming at pier height by, the dosage and a expansion joint size of the support it considered a support shear force and a support displacement with character and property really it did. Also, it produced the bridge lower part construction cost and the analysis of economy which buys the life periodic expense which with the ground which will reach considers a pier height in bridge type by it executed. Life cycle cost it accomplished the value analysis which considers the viewable characteristic, a maintenance effectiveness, a structural safety, a functional characteristic and a usability from economical efficiency and lower part view character. 5)Study conclusion When RB substitute with HDRB, the size of expansion joint which comes to be small, it improve traffic character and a maintenance, the diameter of the pier column is abridged and balanced sight of the bridge it is excellent and the construction is good. A specially it provides many advantage from the under-bridge space application characteristic side. Finally, when seeing from the value engineering side, the cost reduces and the value renovation style type which improves a value it makes

Cell surface display of Neurospora crassa glutamate decarboxylase on Escherichia coli for extracellular Gamma-aminobutyric acid production from high cell density culture

GABA is produced from the decarboxylation of glutamate by glutamate decarboxylase enzyme (GadB). Various hetrologous GadB enzymes has been indentified and introduced in Escherichia coli to improve the productivity of GABA. In this study, cell surface display strategy was employed by displaying Neurospora crassa glutamate decarboxylase (GadB) on the surface of Escherichia coli using OmpC as an anchoring motif. To construct the display system, the GadB was fused to truncated C-terminus of OmpC and expressed in E. coli. The recombinant E. coli displaying GadB has produced 3.03 g/L of GABA from 10 g/L glutamate within 12 h of culture period. When the GadB display system was cultured at high cell density, 100% GABA yeild was achieved from 50 g/L of glutamate. The results suggest that the GadB expression on the E. coli surface is stable and effective on GABA production. The surface display strategy can be applied on other potential enzyme candidates and used in Industry for bulk chemical production

잡음 영상에 대한 영상경계 추출 기법의 개발에 관한 연구

학위논문(석사) - 한국과학기술원 : 전기 및 전자공학과, 1981.2, [ [iii], 78 p. ]The necessities of pattern recognition systems are much increased in many applications. According to their applications, they may be divided into two major groups; speech \& speaker recognition and image-based recognition. Image-based pattern recognition systems, we called image understanding systems, are widely used. In these systems, edge extraction is indispensible in order to classify the given input images. There has been a number of edge extraction techniques. Most of existing edge extraction techniques have some problems, especially for noisy images. We propose a new technique which works well for noisy images. It is based on statistical testings and edge searching procedure. It has additional capability of detecting lines as well as step edges, and can be applicable to various types of Images. Its algorithm is rather complex compared with several existing techniques such as method of using simple edge operators; however, these techniques requires some preprocessing \& postprocessing to have good results. On a while, this proposed technique won``t use any preprocessing and does not need postprocessing, for example edge thinning, etc., which makes computing time to be much saved. Also, most of existing edge extraction techniques have difficulties in selecting a threshold value, whereas for this proposed technique its selection is very easy and it has been found experimentally that the resulting edges are rather insensitive to the particular choice of threshold value, regardless of types of images and amount of noise.한국과학기술원 : 전기 및 전자공학과

재조합 대장균에 의한 숙신산 생산의 대사회로 분석

학위논문(석사) - 한국과학기술원 : 화학공학과, 1999.2, [ vi, 44 p. ]In this study, the possibility of constructing a nonnatural metabolic pathway was evaluated by expression of the malic enzyme in a host which lost fermentation ability. The sfcA gene (1.7 kb) encoding E. coli malic enzyme was cloned by PCR from E coli XL1-Blue. Flask cultures were carried out in LB medium and induced with 0.01 mM IPTG. Higher IPTG concentration resulted in no production of succinic acid. E. coli strain NZN111 harboring pTrcML produced 8 g/L of succinic acid in flask culture. It is 6 times higher than that produced by wild type E. coli. Fermentation studies were carried out at various temperatures and pH. When NZN111 cultured at 30℃ and pH 6.7, 9.5 g/L of succinic acid was produced. Metabolic flux analysis showed that there exist a cyclic pathway among phosphoenolpyruvate carboxylase, pyruvate kinase, and malic enzyme. Overexpression of malic enzyme caused bottle neck, and reduced expression of malic enzyme somewhat resolved the bottleneck problem.한국과학기술원 : 화학공학과

A Novel Strategy for the Microbial Removal of Heavy Metals: Cell-surface Display of Peptides

Cell surface engineering is a rapidly developing technology of microorganism that achieves modification of cell surface function by joining external functional peptides with surface anchoring proteins, for example, Outer Member Protein (OMP). On account of these proteins possessing metal responsive motifs, they can be specifically used for metal adsorption and dissociation. To elucidate the problems caused by heavy metals and develop various technologies for their removel or recovery, various metalbinding proteins/peptides fused on microorganism cell surface have been applied as novel methods. During the past few years, bacterial cell surface display strategy has received growing attention for their availability to eliminate heavy metals. In this paper, the existing problems, progress, and suggestions for furture of the peptide displaying system are summarized

Production of Bacteriorhodopsin by Halobacterium halobium in the Internal Membrane Bioreactor

Bacteriorhodopsin in the purple membrane(PM) of halobacteria has recently been attracting much attention to be used as a component of molecular electron device and optical computers. In order to increase the productivity of bacteriorhopsin in high cell density cultures of Halobacterium halobium R1, an internal membrane cell-retention bioreactor system was emplyed. As a result, the production of cell mass at OD660 of 12 and of Bacteriorhodopsin at 125-130mg/L were obtained using the internal membrane bioreactor system at a dilution rate of 0.066hr. The productivity achieved by the internal membrane system (0.7mg/L hr) was 3.5-fold higher than that obtained by the corresponding batch cultivations(0.2mg/L hr).본 연구는 삼성종합기술원의 96년도 멀티미디어 미래연구과제의 일부로 수행되어 재정적 지원을 받았음을 감사드립니다

Whole-cell display of Pyrococcus horikoshii glutamate decarboxylase in Escherichia coli for high-titer extracellular gamma-aminobutyric acid production

We investigated the effect of cell-surface display of glutamate decarboxylase (GadB) on gamma-aminobutyric acid (GABA) production in recombinant Escherichia coli. We integrated GadB from the hyperthermophilic, anaerobic archaeon Pyrococcus horikoshii to the C-terminus of the E. colt outer membrane protein C (OmpC). After 12 hr of culturing GadB-displaying cells, the GABA concentration in the extracellular medium increased to 3.2 el, which is eight times that obtained with cells expressing GadB in the cytosol. To further enhance GABA production, we increased the temperatures of the culture. At 60 degrees C, the obtained GABA concentration was 4.62 g/I after 12 hr of culture, and 5.35 g/l after 24 hr, which corresponds to a yield of 87.7%