의학강좌 : 개원의를 위한 모범처방 ; 상부위장관 출혈의 치료: 소화성궤양 출혈을 중심으로

강기주 ( Ki Joo Kang ),이준행 ( Jun Haeng Lee ) 대한내과학회 2010 대한내과학회지 Vol.79 No.2

고온에서 박막의 기계적 거동 측정 방법

강기주(Ki-Ju Kang),임상채(Sang Chai Lim),이상신(Sang Shin Lee),전문창(Moon Chang Jeon),주재황(Jae Hwang Joo) 대한기계학회 2002 대한기계학회 춘추학술대회 Vol.2002 No.5

Recently, the authors have developed a new material test system for thin film at the high temperature. It is so compact and precise with sub micron resolution that it seems to be a useful tool for research of the oxide film growth, its mechanical behavior and failure mechanism. To this end, in this paper three methologies are described for in-situ monitoring of the displacement & strain and the temperature, the oxide thickness. These are the Laser Speckle analysis with digital image correlation technique, the two-color infra-red thermometer und the laser reflection interferometry respectively. The calibration results and some issues which should be addressed for practical application are presented.

준 카고메 트러스 심재를 갖는 최적화된 샌드위치 판재의 굽힘하중 하에서의 기계적 성능

임채홍,주재황,강기주,Lim, Chai-Hong,Joo, Jai-Hwang,Kang, Ki-Ju 대한기계학회 2007 大韓機械學會論文集A Vol.31 No.10

Three kinds of metallic sandwich panels with quasi-Kagome truss cores have been analyzed on their mechanical behaviors subjected to bending load. According to the results of previous work on the optimal design, they were designed to have similarly high strength per weight with the identical overall sizes, i.e., the total length, the width, the core height. Differences were in the face sheet thickness and/or the thickness of the metal sheet from which the core was fabricated through expanding and bending processes. Under the bending load, they performed well as designed, as far as the maximum load is concerned. However, after the maximum load, the load-displacement curves were different each other depending on the slenderness ratio of the truss elements composing the quasi-Kagome truss cores and the face sheet thickness. Namely, the slenderness ratio and the face sheet thickness governed stability of the elastic and plastic buckling. Therefore, if energy absorption characteristics or structural stability as well as the maximum load capacity are to be achieved, the sandwich panel with thick truss members and thick face sheet should be selected.

알루미늄 나선형 와이어로 직조된 다층 Kagome Truss PCM의 유동 및 열전달 특성에 관한 연구

주재황(Jai-Hwang Joo),강보선(Bo-Seon Kang),강기주(Ki-Ju Kang) 대한기계학회 2008 大韓機械學會論文集B Vol.32 No.1

Recently, ultra-lightweight materials with open, periodic cell structures take much attention owing to its potential for multi-functionality such as load bearing, thermal dissipation, and actuation. This paper presents experimental results on the fluid flow and heat transfer characteristics for the Wire-woven Bulk Kagome (WBK) composed of aluminum 1100 wires. The overall pressure drop and heat transfer of the WBK specimen was experimentally investigated under forced air convection condition. The pressure loss and heat transfer performance of the aluminum WBK were compared with other heat dissipation media. It was shown that heat transfer characteristics depended on relative density and surface area density. Comparison with metal foams and other heat dissipation media such as packed beds, lattice frame materials, louvered fins, and others suggests that the aluminum WBK competes favorably with the best available heat dissipation media in heat transfer performance.

부분충진된 WBK 트러스 다공질 금속의 압축 특성 평가

주재황(Jai-Hwang Joo),박종선(Jong-Sun Park),강기주(Ki-Ju Kang) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.5

Lightweight cellular metals combining load supporting capability and thermal management characteristics are required for multifunctional applications. Recently, a new technique for fabricating cellular metal, known as Wire-woven Bulk Kagome (WBK), has been introduced, which is used for fabricating multilayered Kagome truss-type cellular metal. The WBK is composed of helically formed wires and it has been proved that it has high strength-per-weight. In this work, a partially filled WBK with very high specific strength was devised to suppress the elastic buckling of struts which is a typical failure mechanism of truss type PCM (periodic cellular metals). First, theoretical studies using elementary mechanics of material are presented to estimate the strength under out-of-plane compression. And the results are compared with those measured by experiments which were performed with specimens with various slenderness ratios of struts. It has been found that the partially filled WBK exhibited high specific stiffness and strength, absorption of energy in comparison with ordinary WBK.

확장금속망 공정으로 제작된 옥테트 트러스 다공질 금속 : 제3보: 굽힘하중에서의 기계적 성능

주재황(Jai-Hwang Joo),강기주(Ki-Ju Kang) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5

Recently, a new idea was introduced for fabricating sandwich panels with tetrahedral truss cores by metal expanding and folding processes. The results from the three-point bending tests of sandwich panels were investigated. Specifically, the load capacity of the sandwich panel subjected to bending load was estimated by energy based approach for various failure modes. A failure map was constructed as functions of strut and face sheet thickness for a given core height, H<SUB>c</SUB>=16.33㎜ and for a given material parameter, ε<SUB>y</SUB>=0.00089. By using the map, three designs were chosen for maximum load per weight ratio. Namely, design variables for Design-1 specimen were based on the triple point of the face sheet buckling, face sheet yielding, and core shear-mode B plastic regime, whereas those of Design-2 and -3 specimens were based on the boundary between face sheet yielding and core shear-mode B plastic regime. Design-3 had the thickest truss struts and face sheets. In three-points bending tests, the critical loads and the corresponding failure modes were in good agreement with the estimated ones. However, Designs-1 was substantially inferior to Design-2 and -3 in terms of the energy absorption and deformation stability after the peak point.

한국인 신이식 환자에서 Interleukin-10과 Interferon-γ의 유전자 다형성이 이식신의 임상경과에 미치는 영향

박성훈 ( Sung Hoon Purk ),강기주 ( Ki Joo Kang ),송영림 ( Young Rim Song ),채동완 ( Dong Wan Chae ),오국환 ( Kook Hwan Oh ),김성균 ( Seong Gyun Kim ),노정우 ( Jung Woo Noh ),이영기 ( Young Ki Lee ),임춘수 ( Chun Su Lim ),김연수 ( 대한신장학회 2002 Kidney Research and Clinical Practice Vol.21 No.6

목 적 : Interleukin-10 (IL-10) 유전자 프로모터 (promoter)에 존재하는 3가지 단일 염기 다형성 (aingle nucleotide polymorphism : SNP)과 Interferon-γ (INF-γ) 유전자 첫 번째 인트론의 allele*C와 *A의 병렬적 반복횟수의 다형성 (variable numbers of tandem repeat : VNTR)은 각각 mitogen 자극에 의한 IL-10과 IFN-γ의 생성량에 영향을 주는 것으로 보고되고 있다. INF-γ와 IL-10은 각각 주된 Th1과 Th2 사이토카인으로 이식항원에 대한 개체의 면역반응에 중요한 역할을 한다. 따라서 이식 환자의 유전적 다형성에 따른 이식항원에 대한 IFN-γ와 IL-10의 생성양의 차이는 이식신에 대한 면역반응의 차이를 유발하고 궁극적으로 이식신의 임상경과에 영향을 미치리라 판단된다. 이에 연구자들은 신이식 수술을 받은 한국인 환자에서 IFN-γ와 IL-10의 유전자 다형성을 조사하고, 이들 사이토카인의 유전적 다형성이 이식신의 임상적 경과에 미치는 영향을 파악하고자 본 연구를 시행하였다. 방 법 : 1991년부터 2000년까지 강동성심병원에서 신이식 수술을 받고 5개월 이상 추적 관찰된 185명의 환자와 혈압이 정상이고 병력 및 검사소견에서 신질환의 증거가 없는 98명의 대조군을 대상으로 하였다. PCR과 특정 제한효소를 이용한 PCR -RFLP의 방법으로 IL-10 promoter의 세 가지의 SNP를 조사하였고, IFN-γ 유전자 첫 번째 인트론에 존재하는 CA 염기의 VNTR은 PCR 생성물의 크기에 따라 측정하였다. 유전적 다형성과 이식 환자의 임상적 경과의 관련성은 Chi-square test와 fisher`s Exact test 및 student t-test를 이용하여 평가하였다. 결 과 : IFN-γ에서는 신이식 환자와 대조군간의 allele*2와 allele*3의 분포의 차이는 없었다. 모든 연구 대상에서 IL-10 promoter의 전사시작부위에서 -592 위치의 allele*A와 *C은 각각 -819 위치의 allele*T와 *C과 연관 (ilnkeage)되었다. -1,082 위치의 *C/*A genotype은 신이식 환자에서 7.0%로 대조군의 17.3%에 비하여 낮았다(p=0.02). *C/*G genotype은 모든 대상 환자에서 관찰되지 않았다. IL-10와 IFN-γ의 유전적 다형성은 급성거부반응의 빈도나 중증조와는 관련이 없었고, 추적 관찰기간 중 혈청 크레아티닌 농도의 증가에도 영향을 주지 않았다. 결 론 : 한국인의 IFN-γ첫 번째 intron의 VNTR 다형성의 분포는 서양인에서의 보고와 유사하였으나 IL-10 promotor SNP 다형성은 서양인과 대단히 상이한 분포가 관찰되었고 -1,082 *G/*A genotype의 빈도가 신이식 환자에서 대조군에 비하여 낮았다. 한국인에서의 IL-10와 IFN-γ의 유전적 다형성은 이식신의 임상적 경과에 의미있는 영향을 주지 못하였다. Background : The single nucleotide polymorphism (SNP) of interleukin-10 and the variable number of tandem repeat (VNTR) of CA dinucleotide of Interferon-γ are reported to have an influence on the production of IL-10 and IFN-γ respectively. The aims of this study are to investigate the gene polymorphisms of IL-10 and IFN-γ in Korean renal transplant patients and to assess their impacts on the clinical courses of renal allografts. Methods : The one hundred eighty-five patients who received renal allografts and were followed for more than 5 months from 1991 to May 2000 in Kangdong Sacred Heart Hospital, and ninety-eight normal healty controls were investigated, Three SNPs in promoter region of IL-10 gene were assayed by PCR-RFLP. The (CA) dinucleotide repeat polymorphism of IFN-γwere assessed by evaluation of size of PCR products. Results : Allele*2 and allele*3 were major alleles of IFN-γ in our study and there was no significant difference of alleleic and genotypic distribution between recipient and control group. The -592*A and -592*C in the IL-10 promotor region were tightly linded to -819*T and -819*C, respectively. The frequency of -1082*G/*A genotype of recipent group was 7.0% and smaller than that of control group (17.3%, p=0.02). The *G/*G genotype (IL-10 high producer) was absent in all our study subjects, which was quite different from Western studies. IFN-7 and IL-10 gene polymorphisms had no impact on the incidence and severity of acute rejection, and long term graft fucntion after transplantation. Conclusion. Unlike IFN-γ the SNPs of IL-10 promoter were qua different from those in Western patients. The frequency of -1,082*G/*A genotype of IL-10 was smaller in recipient group. In conclusion, the polymorphisms of IL-10 and IFN-γ had no impact on the clinical courses of renal allografts under the current therapeutic strategies.

알루미늄 나선형 와이어로 직조된 다층 Kagome truss PCM의 유동 및 열전달 특성에 관한 연구

주재황(Jai-Hwang Joo),강보선(Bo-Seon Kang),강기주(Ki-Ju Kang) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.5

Recently, ultra-lightweight materials with open, periodic cell structures take much attention owing to its potential for multi-functionality such as load bearing, thermal dissipation, and actuation. This paper presents experimental results on the hydraulic and heat transfer characteristics for the Wire-woven Bulk Kagome(WBK) composed of aluminum 1100 wires. The overall pressure drop and heat transfer of the WBK specimen have been experimentally investigated under forced air convection condition. The pressure loss and heat transfer performance of the aluminum WBK are compared with other heat dissipation media. It was shown that heat transfer depended on relative density and surface area density. Comparison with metal foams and other heat dissipation media such as packed beds, lattice frame materials, louvered fins, and other materials suggests that the aluminum WBK competes favorably with the best available heat dissipation media in heat transfer performance.

확장금속망 공정으로 제작된 옥테트 트러스 다공질 금속

주재황(Jai-Hwang Joo),강기주(Ki-Ju Kang) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.10

Many studies have been performed on manufacture and optimization of truss PCM(periodic cellular metal) structures. The tetrahedral truss cores are manufactured through metal expanding and bending process and then brazed with solid face sheets. The new metallic sandwich plates with the tetrahedral truss cores subject to 3-point bending have been investigated. The equations of failure load corresponding to the eight failure modes are presented and then non-dimensional forms of the equations are derived. The maps of failure mechanism are constructed based on the analytical calculations in the non-dimensional parameters of geometry. The performance of modified octet truss sandwich plates are compared with similarly octet and honeycomb sandwich plates of the same materials.

확장금속망 공정으로 제작된 옥테트 트러스 다공질 금속 (Ⅰ)

주재황(Jai-Hwang Joo),이동석(Dong-Seok Lee),전인수(Insu Jeon),강기주(Ki-Ju Kang) 대한기계학회 2007 大韓機械學會論文集A Vol.31 No.11

This paper presents a new way for fabricating sandwich plates with tetrahedral truss cores. The tetrahedral truss cores are manufactured through metal expanding and bending process and then brazed with solid face sheets. The properties of sandwich plates with the tetrahedral truss cores composed of a wrought steel SS41 under compression and shear loading have been investigated. Good agreement is observed between the measured and predicted peak strengths. Comparisons with normalized compressive strength for other cellular metals have indicated that the tetrahedral truss structures outperform aluminum open cell forms and woven core sandwich plates.