폴리우레탄 스프링 복원형 디스크 받침의 동적거동에 대한 실험 및 해석적 연구

박형기,이유인,정대유 한국지진공학회 2011 한국지진공학회논문집 Vol.15 No.2

이 논문에서는 근래에 널리 사용되는 면진 장치인 폴리우레탄 스프링 복원형 디스크 받침의 동적거동에 영향을 미치는 구성재료의 인자에 대한 분석을 수행한 후, 그 결과를 이용하여 받침의 거동을 예측하여 거동 시험결과와 비교하였다. 여기서 동적거동에 영향을 미치는 인자로는 속도와 접촉압력에 따라 변하는 불소수지판(PTFE, PolyTetraFluoroEthylene, 폴리테트라플루오로에틸렌)의 마찰계수와 변형률에 따라 변화하는 폴리우레탄 스프링의 탄성계수가 고려되었다. 불소수지판은 W-PTFE virgin 제품을 사용하였고, 폴리우레탄 스프링은 직접 제작한 것을 사용하였다. 접촉압력, 속도에 따른 마찰계수 변화와 변형률에 따라 변하는 폴리우레탄 스프링의 탄성계수를 모사하는 식은 각각의 시험결과로부터 역추정 하여 사용하였다. 동특성 영향인자를 고려한 거동의 예측 결과는 동특성이 고려되지 않고 정적 인자만을 고려한 예측 결과보다 시험결과와 더 적절한 일치성을 보여주었다. In this paper, the factors affecting the dynamic characteristics of a polyurethane spring restoring disk bearing are analysed to predict the dynamic behavior of the bearing. The prediction results and the test results are compared. The Young's modulus of the polyurethane spring, which varies according to strain of spring and the friction coefficient, of PTFE (PolyTetraFluoroEthylene), which varies according to the velocity and pressure of PTFE, are considered as the factors influencing the dynamic characteristics. W-PTFE virgin products are used and polyurethane springs are produced for the tests. The equation related to changing the friction coefficient and the modulus of elasticity are obtained through an inverse estimation of the test results. The estimation results, considering the factors affecting the dynamic characteristics, simulate the test results more appropriately than the estimation without the consideration of those factors.

해외 제조공장의 품질보증 및 고장분석을 통한 신뢰성 성장 설계

박형기 국제차세대융합기술학회 2023 차세대융합기술학회논문지 Vol.7 No.12

본 논문은 해외 공장에서 제조된 부품의 품질 수준을 파악하고 시장 불량에 직결되는 위험인자를 발굴, 불량 발생원인 파악 및 고장 분석을 개선된 프로세스로 수행한다. 또한 전기 제품내의 요소부품을 규정, 고질불량 문제 해결을 위해 TFT(Task Force Team)를 구성하는 방법과 절차를 소개한다. 특히 해외공장은 간단하고 명료 한 품질 시스템이 요구되므로 국내공장에서 확실하게 검증된 방법을 적용해야 만이 실수가 없다. 해외공장의 특수 성 때문에 지역별 품질경영 시스템이 동반되어야 하고 품질지수를 높일 수 있는 신뢰성 성장 설계를 하도록 노력 해야 한다. 개발 단계별 차기 진행여부에 대한 결정이 필요하고 중요도, 시장상황에 맞게 판정해야한다. 최고의 제 품은 사람으로부터 나오게 되므로 협력업체와의 부품 품질관리는 양 사간 공동의 관심이 필요하고 불량품 개선 후 재발되지 않는 유지관리 시스템을 명문화하여 정착시킬 필요가 있다. This paper identifies the quality level of parts manufactured in overseas factories, discovers risk factors directly linked to market defects, identifies the cause of defects, and conducts fault analysis with an improved process. It also introduces methods and procedures for configuring a TFT (Task Force Team) to define elemental parts in electrical products and solve chronic defect. In particular, overseas factories require a simple and clear quality system, so there is no mistake only when a method that has been reliably verified in domestic factories is applied. Due to the specificity of overseas factories, regional quality management systems should be accompanied, and efforts should be made to design reliable growth that can increase the quality index. It is necessary to decide whether to proceed in the next stage of development, and it should be determined according to its importance and market situation. Since the best product comes from humans, component quality management with partner companies requires joint attention between the two companies and needs to be established by stipulating a maintenance system that does not recur after improving defective products.

돼지고기는 장수식품

박형기,Park, Hyeong-Gi 대한양돈협회 1990 養豚 Vol.12 No.1

지반-구조물 연계모델의 등가감쇠값에 관한 연구

박형기,Park, Hyung Ghee 대한토목학회 1987 대한토목학회논문집 Vol.7 No.3

지반-구조물 상호작용 효과가 큰 경우의 동적문제를 모드중첩법으로 해결하기 위하여 여러 가지 등가모드감쇠값 결정 방법에 대한 이론적 배경을 검토하였다. 또한 component mode synthesis method에 의하여 감쇠행렬을 구하고 이를 이용한 직접적분법으로 지반-구조물의 연계모델의 응답을 계산하여 각 등가모드감쇠값 결정 방법으로 구한 등가모드감쇠값을 사용한 모드 중첩법의 해석 결과와 비교 분석하였다. 해석모델로는 2종류의 상부구조와 4종류의 지반조건을 고려하고 이를 조합한 경우를 채택하였다. 본 연구 결과로 소멸에너지법으로 얻은 등가모드감쇠값이 직접적 분법의 결과에 가장 근사적인 결과를 주는 것을 알 수 있었다. 고정지반모델인 경우에는 강도가중법을 제외한 다른 방법으로 구한 등가모드감쇠값은 직접적분법의 결과와 거의 일치되는 응답을 주었다. The theoretical backgrounds of the several methods were surveyed and reviewed to fin out the adequate one to determine equivalent modal damping values in solving the dynamic problem of soil-structure interaction by mode superposition method. Furthermore the rigorous damping matrix of equation of motion was obtained through component mode synthesis technique and used in direct integration of the equation. The analytical results by direct integration method were compared with those of mode superposition approach using the various sets of equivalent modal damping values calculated by the methods to be reviewed. Two types of superstructures and four kinds of subsurface conditions were considered and combined to make soil-structure coupled models. It was realized that dissipating energy method gives the equivalent modal damping values which lead the most similar results to direct integration ones. In case of fixed base, the responses of all methods except stiffness weighted approach are almost equal to those of direct integration method.

構造解析用 프로그램 STARDYNE의 紹介

朴滎基(박형기) 대한토목학회 1980 대한토목학회지 Vol.28 No.4

해석(解析)모델의 구조변수(構造變數) 변동(變動)이 동적응답에 미치는 영향(影響)

박형기,임부영,Park, Hyung Ghee,Lim, Boo Young 대한토목학회 1993 대한토목학회논문집 Vol.13 No.3

부분구조법(部分構造法)으로 프리스트레스드 콘크리트 원자로격납건물(原子爐格納建物)의 지진에 대한 확률위험도분석이나 내진 안전여유평가시 상부구조에 관한 입력자료(入力資料)가 되는 구조물(構造物)의 고유전동수와 구조물 상부에서의 최대가 속도값의 구조변수(構造變數)에 대한 변동성이 연구되었다. 본 연구는 먼저 구조모델의 고유진동수에 가장 큰 영향을 미치는 구조변수를 결정하기 위하여 각 구조변수(構造變數)의 상대적(相對的) 민감도(敏感度)를 분석(分析)하였고, 각 변수의 결정에 포함될 수 있는 불확실성(不確實性)의 정도를 고려하여 Monte Carlo 수치모형실험을 수행하였다. 최대 가속도값의 변화는 직접적분(直接積分)에 의한 시간이력곡선법으로 분석되었다. 연구결과로 첫번째모드의 고유 진동수와 건물 정상부의 최대가속도값은 각 변수중 탄생계수의 영향을 가장 크게 받으며, 결정론적 방법으로 구한 값과 비교할 때 확률론적 방법으로 구한 값(평균+표준편차)은 (+)12% 정도 변함을 알 수 있다. 또한 휨강성의 불확실성을 고려하면 동적응답은 (-)4%~(+)14% 정도 달라진다. The variations of the natural frequencies and the peak response acceleration at the top of prestressed concrete reactor building due to random variability and/or model uncertainty of structural parameters are studied. The results may be used as essential input parameters in seismic probabilistic risk assessment or seismic margin assessment of the reactor building. The sensitivity test of each structural parameter is first performed to determine the most influential parameter upon the natural frequency of structure model. Then Monte Carlo simulation technique is applied to evaluate the effect of parameter variation on the natural frequencies and the peak response acceleration. The acceleration time history is obtained by direct integration scheme. As the study results, it is found that the fundamental natural frequency and the peak response acceleration at the top of the building are most strongly affected by Young's modulus among the structural parameters, in which the value of mean plus one standard deviation obtained by probabilistic approach deviates up to about (+)12% from the result of deterministic method. Considering the uncertainty of flexural rigidity, the structural responses vary in range of (-)4%~(+)14%.

현수교 PWS 및 CFRC 행어로프의 내풍안정성 실험 평가

박형기,강선진,Park, Hyung-Ghee,Kang, Seon-Jin 한국방재학회 2008 한국방재학회논문집 Vol.8 No.6

In this study, to evaluate the aerodynamic stability of suspension bridge hanger ropes, the wind tunnel tests are carried out. It is found that the vortex induced vibration is detected only in single PE-coated PWS cable case. And the wake galloping is occurred in twin cables spaced $3\sim6$ cable diameters of cable center to center when the incidence angle of wind is only zero degree. In case of other incidence angles of wind except zero degree, the wake galloping or the wake flutter are showed in twin cables even outside range of the bounds of $3\sim6$ cable diameters. CFRC cable shows very stable for the twin cables regardless of the distance between two cables, and also for various incidence angles of wind. Thus the characteristic of CFRC rope overwhelms one of PWS cable in aerodynamic stability. 이 연구에서는 현수교 PWS 및 CFRC 행어로프의 바람에 의한 내풍안정성 평가을 위한 풍동실험을 수행하였다. 풍동실험결과, PE관으로 피복된 PWS 케이블은 단일 케이블에서 와류진동이 발생하고 복수 케이블에서는 중심간격이 $3\sim6D$일때 웨이크갤로핑이 발생하였다. 진동이 발생하지 않는 복수 케이블에서도 풍향각이 달라지면 웨이크갤로핑이나 웨이크플러터가 발생함을 알 수 있었다. CFRC 케이블은 케이블 중심간격 및 풍향각에 관계없이 PWS 케이블에 비해 안정된 내풍성능을 보였다.

만성 B형 간염 환자의 간조직내 HBs Ag 및 HBc Ag 출현에 관한 면역조직화학적 연구

박형기 고려대학교 의과대학 1987 고려대 의대 잡지 Vol.24 No.3

To evaluate correlation of HBs Ag and HBc Ag in the liver with histologic activity and diagnostic implication, the author has investigated expression patterns of HBs Ag and HBc Ag in 88 biopsied liver tissue from chronic hepatitis B. with indirect immunohistochemical method HBs Ag and HBc Ag were detected and classified as focal, patchy and diffuse patterns. The above results were compared with several serologic profiles and histologic activity which was arbitrarily established. The results are as followings. 1. HBs Ag in the liver was dectected in 97% and HBc in 72%, HBc Ag was found in the nucleus (47%) or in the cytoplasm (48%) or in both (33%). 2. Comparing to several serologic profiles, HBs Ag in the liver tissue was detected in 97% Of the cases with seropositive HBs Ag and HBe Ag, with expression patterns of focal 36%, patchy 28% And diffuse 34%. In cases with seropositive HBs Ag and Anti-HBe Ab, HBs Ag in the liver tissue was detected in 100% With patterns of focal 67%, patchy 16.5% and diffuse 16.5%, and in cases with seropositive HBs Ag and Anti-HBe Ab, HBs Ag in the liver tissue was noted in 90% With patterns of focal 30%, patchy 40% And diffuse 20%. 3. Comparing several serologic profiles, HBc Ag in the nucleus was detected in 53% With seropostive HBs Ag and HBe Ag and Anti-HBs Ab, nuclear HBc Ag was noted in 40%, with patterns of focal 30% And patchy 10%. 4. HBs Ag in the liver according to histologic activity showed 98% In grade Ⅰ, with patterns of focal 40%, patchy 28% And diffuse 30%, In grade Ⅱ HBs Ag in the liver was detected in 94%, with patterns of focal 55%, patchy 27% And diffuse 13% And in grade Ⅲ HBs Ag in the liver showed 95% With patterns of focal 22%, patchy 30% And diffuse 43%. 5. HBc Ag in the nucleus according to histologic activity showed in 44% in grade Ⅰ, with expression patterns of focal 21%, patchy 18% And diffuse 5%. In grade Ⅱ HBc Ag was detected in 45% With patterns of focal 31%, patchy 5% And diffuse 9% And in grade Ⅲ, HBc Ag was detected in 52% With patterns of focal 48%, patchy 4% And diffuse 0%. With above results, it is thought that HBg Ag in the liver is signficantly reated with HBs Ag antigenemia and HBc Ag in the liver is colosely related with serum HBe Ag or Anti-HBe Ab in chronic hepatitis B. The expression patterns of HBs Ag and HBc Ag in the liver are so variable that they could not access the diagnostic implication. But in chronic active hepatitis, the more abundant HBs Ag in the liver, the more histologic activity is found, in contrary the more abundant HBc Ag in the liver, the less histologic activity is noted.

차량재하시험에 의한 구조물 동특성 평가에 웨이블렛변환의 이용

박형기 한국구조물진단유지관리공학회 2005 한국구조물진단유지관리공학회 논문집 Vol.9 No.2

반데르발스 소재 기반의 태양전지 적용에 관한 최신 연구동향 리뷰

박형기,이재현,허근 대한금속·재료학회 2024 대한금속·재료학회지 Vol.62 No.2

In recent years, the exploration of van der Waals materials has taken center stage in the fieldof advanced materials research. Studies have delved deeply into the multifaceted characteristics of thesematerials, and in particular their potential applications in solar cell technology. Van der Waals materials,named after the unique forces binding their layers, are of high interest because of their unparalleledphysical and chemical properties. Their two-dimensional (2D) nature offers a plethora of advantageousfeatures, including a high surface-to-volume ratio, which is crucial to enhanced light absorption andelectron transport. The tunable electronic properties of these materials also offer a versatile platform forcustomizing behavior to meet the specific requirements of solar cell applications. Their distinctive opticalcharacteristics can also be enhanced to improve light absorption and reduce energy losses, therebyincreasing overall solar cell efficiency. Recent research has not only investigated the inherent propertiesof van der Waals materials but also explored various techniques to combine and stack them. Suchmethodologies aim to exploit and optimize the synergistic effects of different materials, paving the wayfor next-generation solar cells with improved performance metrics. A comprehensive examination of theoperating principles of these materials provides insights into their interaction with light and theirsubsequent electrical behavior. The study concludes with a forward-looking perspective, emphasizing howthe integration of van der Waals materials could very well revolutionize the solar cell industry. Theirpotential to significantly boost the efficiency and stability of solar cells positions them as promisingcandidates for future sustainable energy solutions.