원자로 하부구조의 온도상승에 따른 열화를 완화하기 위한 외벽보강 최적설계

김기풍,김현섭,허훈,박재홍,이종인,Kim, Kee-Poong,Kim, Hyun-Sup,Huh, Hoon,Park, Jae-Hong,Lee, Jong-In 대한기계학회 2000 大韓機械學會論文集A Vol.24 No.11

This paper is concerned with the optimum design for external reinforcement of a nuclear reactor pressure vessel(RPV) in a severe accident. During the severe reactor accident of molten core, the temperature and the pressure in the nuclear reactor rise to a certain level depending on the initial and subsequent condition of a severs accident. The reis of the temperature and the internal pressure cause deterioration of the load carrying capacity and could cause failure of the RPV lower head. The deterioration of failure can be mitigated by the external cooling or the reinforcement of the lower head with additional structures. While the external cooling forces the temperature of an RPV to drop to the desired level, the reinforcement of the lower head can attain both the increase of the load carrying capacity and the temperature drop. The reinforcement of the lower head can be optimized to have the maximum effect on the collapse pressure and the temperature at the inner wall. Optimization results are compared to both the result without the reinforcement and the result with the designated reinforcement.

External reinforcement of hydrocarbon membranes by a three-dimensional interlocking interface for mechanically durable polymer electrolyte membrane fuel cells

Yuk, Seongmin,Yuk, Jinok,Kim, Tae-Ho,Hong, Young Taik,Lee, Dong-Hyun,Hyun, Jonghyun,Choi, Sungyu,Doo, Gisu,Lee, Dong Wook,Kim, Hee-Tak Elsevier 2019 Journal of Power Sources Vol.415 No.-

<P><B>Abstract</B></P> <P>Although, the use of hydrocarbon membranes is one of the ways to reduce the cost of polymer electrolyte membrane fuel cells, it cannot be practically adopted due to its low mechanical durability under a dynamic wet/dry operation. Here, we present an externally-reinforced hydrocarbon membrane achieved by a three dimensional interlocking interfacial layer which forms a strong interfacial bonding between the hydrocarbon membrane and the catalyst layers. Although a conventional hydrocarbon membrane is easily delaminated from gas diffusion electrodes, the use of the three dimensional interlocking interfacial layer, prepared with a polystyrene nanoparticle template method, enhances the interfacial adhesion by 207 times. The hydrocarbon membrane, tightly connected to the gas diffusion electrodes by the three dimensional interlocking interfacial layers, has a humidity cycling durability that is 1.9 times higher in the membrane electrode assembly level by restricting the dimensional change of the membrane. Furthermore, due to the proton conducting property of the three dimensional interlocking interfacial layer, the external reinforcement does not cause any power performance losses.</P> <P><B>Highlights</B></P> <P> <UL> <LI> An externally-reinforced hydrocarbon (HC) membrane is demonstrated. </LI> <LI> 3D interlocking interface tightly binds the HC membrane and gas diffusion electrode. </LI> <LI> The mechanical stability of the HC membrane is improved by 3D interlocking interface. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

대형 축조블록을 이용한 보강토옹벽의 안정성 평가

한중근(Jung-Geun Han),김민우(Min-Woo Kim),홍기권(Kikwon Hong),윤중만(Jung-Mann Yun) 한국지반신소재학회 2014 한국지반신소재학회 논문집 Vol.13 No.4

본 연구에서는 대형 축조블록과 지오그리드 보강재를 이용한 보강토 옹벽의 안정성을 검토하였으며, 이를 바탕으로 구조물의 적용에 대하여 평가하였다. 안정성은 옹벽높이, 뒤채움 흙의 강도 및 지오그리드 보강재의 강도 조건에 따른 외적 및 내적안정성을 검토하였다. 외적안정성 분석 결과, 보강재의 길이는 전면벽체 저면으로부터 산정된 옹벽높이의 0.7H와 보강재 수직 간격을 1m로 설치하였을 때, 뒤채움 흙의 내부마찰각 및 옹벽 높이에 관계없이 모든 해석조건에서 기준안전율을 만족하였다. 내적안정성의 경우에는 뒤채움 흙의 내부마찰각이 25°인 경우에도 일부 옹벽 높이에서 파단 및 인발에 대한 안정성이 확보할 수 있는 것으로 나타났다. 특히, 내적안정성 평가결과를 바탕으로 대하여 구조적 안정성 및 경제성을 고려할 수 있는 구조물로의 적용이 가능할 것으로 확인되었다. This paper describes external and internal stability of reinforced earth wall using large-scale modular block and geogrid reinforcement. The evaluation for external and internal stability was conducted to analyze effect of wall height, reinforced soil (or backfill soils) and reinforcement strength. The external stability showed that the analysis cases were satisfied with design criteria, when the required minimum length and vertical spacing of reinforcement were 0.7H and 1m, respectively. The internal stability conformed that some cases were satisfied with design criteria in 25° of internal friction angle of reinforced soil. Expecially, it will be applicable as wall structure considering a structural stability and economic efficiency based on evaluation of internal stability.

외부보강된 밀봉 상태가 다른 Bi-2223테이프의 가압 LN₂하에서 임계전류의 굽힘변형률 의존성

신형섭,박정수,Shin, Hyung-Seop,Dizon, John Ryan C,Park, Jeong-Soo,Rolley, Bonifacio 한국전기전자재료학회 2007 전기전자재료학회논문지 Vol.20 No.6

The critical current degradation behaviors of multifilamentary Bi-2223 superconducting tapes under pressurized liquid nitrogen were investigated using a r-shaped sample holder which gives a series of bending strains to tape. Three kinds of externally-reinforced Bi-2223 tapes with different hermeticity were used as samples. The tape with the thicker reinforcement layer had a better bending strain tolerance of $I_c$, but when the bending strain was calculated at the outermost filament, the $I_c$ degradation behavior became identical. For all samples, $I_{c0}$ decreased with the increase of applied pressure, but the $I_c$ degradation behavior with bending strain at each pressure level was similar. Furthermore, after depressurization from 1 MPa to atmospheric pressure, $I_c$ was completely recovered to its initial values. When the samples were warmed up to room temperature after pressurization tests, the ballooning damage occurred at lower bending strain regions. The region where ballooning was observed was identical to the one where the significant $I_c$ degradation occurred.

주식투자자의 행동이 투자자의 만족에 미치는 영향에 관한 연구

윤재희,송동근 동중앙아시아경상학회 2011 동중앙아시아연구 Vol.22 No.2

본 연구에서는 주식시장에서 주식투자를 하고 있는 주식투자자들의 만족정도에 미치는 영향요인들을 주식투자자 행동요인과 주식투자자 특성요인으로 구분하고, 주식투자자 행동요인은 위험선호도, 정보신뢰성, 내외통제성, 증권사서비스로 구분하고 주식투자자 특성요인은 투자규모와 투자경력으로 구분하여 이들 요인들과 주식투자자의 만족간의 영향관계를 알아보았다. 분석결과에 의하면, 위험선호도는 주식투자자의 만족과 유의한 정(+)의 영향관계가 나타났고 증권사서비스와 주식투자자의 만족과도 유의한 정(+)의 영향관계가 나타났다. 따라서 증권사서비스수준이 높을수록 투자자의 만족수준이 높아진다고 할 수 있다. 또한 투자경력기간과 투자자의 만족수준간의 관계를 알아본 회귀분석결과에 의하면 투자규모만 유의한 정(+)의 영향관계가 나타나 투자 규모가 클수록 만족수준도 높다고 할 수 있다. 본 연구의 유용성은 설문조사를 통해 우리나라 주식투자자의 만족수준의 영향요인인 주식투자자의 행동요인과 주식투자자의 특성요인이 주식투자자의 만족에 미치는 영향을 알아보았다는데 의의가 있다. 하지만 조사대상 범위가 한정되고, 정량적 자료를 이용하지 못하였다는 점 등이 한계로 지적할 수 있다. This study is intended to find out how much impact is given on the stock investor's satisfaction by various factors affecting investor satisfaction at the stock market. These factors are classified into investors' behavior and their characteristics. The relationship between these factors and investor satisfaction is researched in this study. More concretely, the behavior of stock investor is categorized into risk preference, information credibility, service by securities company, and the internal versus external control of reinforcement. The investors' characteristic factors are divided into factors such as investment amount and investment experience etc. According to this analysis, among stock investors' behaviors, the risk preference has a meaningful (+) relationship with investor satisfaction. The service of securities company also has a firm (+) relationship with investor satisfaction. According to the relationship between the investors' characteristics and investor satisfaction, only the investment amount has a meaningful (+) relationship with satisfaction of investor. This means that the investors with more investment amount in market tend to have higher level of satisfaction. The usefulness of this study is found in the process of knowing how much the satisfaction factors of Korean stock investor could give impacts to the investor satisfaction through a field research. The limitation of this study, however, can be indicated that the boundary of the field research was limited. In the future, the additional effort is needed to the generalization of the theory by more in-depth and longer term field research and subdivision of factors affecting on investor satisfaction.

FRP-알루미늄 유공 복합보로 보강된 철근콘크리트 부재의 성능평가에 관한 연구

이상현,최열,박춘옥 대한건축학회지회연합회 2007 대한건축학회지회연합회 학술발표대회논문집 Vol.2007 No.1

RC보의 부착보강공법과 외부강선보강공법의 유효응력에 관한 연구

박용걸,최정열,최준혁 한국철도학회 2007 한국철도학회논문집 Vol.10 No.2

This study was performed to compare the load-carrying capacities of the reinforced concrete structure between the carbon fiber adhesion reinforcement method and the external post-tensioning method and further estimate the effective stress of the reinforced material by analyzing the experimental reinforcing effect of each method and the behavior resulting from each method. As a result, it was found out that the effective stress of the carbon fiber reinforcement according to the carbon fiber adhesion reinforcement method had an unexpected value, and also, bearing of the stress was found to be far from sharing thereof. That is to say, while the carbon fiber was bearing the whole stress to some limits, it got to be momentarily ruptured as soon as it went beyond such limits. On the other hand, the external post-tensioning method has the advantage of inducing an initial effective stress by introducing a strain, and thus, it was found that behavior or bearing of the stress was also found to be a solid behavior of the steel wire. This method was also found to be more efficient and excellent than the carbon fiber adhesion reinforcement method in the reinforcing effect or securing the effective stress. Accordingly, we were to discuss the effective stress as comparatively examined, focusing on deriving of the more enhanced reinforcing effect on the basis of the experiment to which the field characteristic is added.

강봉으로 보강된 RC 사각기둥의 내진 성능 평가

이동민,이성철,신동호,오창국 한국전산구조공학회 2023 한국전산구조공학회논문집 Vol.36 No.5

최근 국내에서 연간 지진 발생 횟수가 꾸준히 증가함에 따라 공공시설물에 대한 내진 보강의 필요성이 더욱 대두되고 있다. 이 연구에서는 사각 단면을 가진 철근콘크리트 기둥에서 강봉보강의 유무에 따른 내진 성능 개선 효과를 분석하기 위해 비선형 유한요소해석을 수행하였으며, 검증을 위해 구조실험결과와 비교하였다. 분석 결과, 이 연구에서 수행한 유한요소해석이 실제 강봉보강공법을 적용한 철근콘크리트 기둥의 구조 거동을 합리적으로 잘 묘사하는 것으로 나타났다. 또한, 해석 및 실험 모두 강봉보강공법 적용으로 인해 파괴모드가 취성파괴에서 연성파괴로 전환되었으며, 강도와 연성도 모두 증가하는 것으로 나타났다. 따라서, 강봉보강공법 적용을 통해 기존 철근콘크리트 기둥의 내진 성능을 효과적으로 증진시킬 수 있는 것으로 판단된다. 이 연구의 주요 결과는 향후 설계 방안 마련 등 관련 연구에 유용할 것으로 기대된다. With the steady increase in the annual number of earthquakes in South Korea, the need to apply seismic reinforcement on public facilities has recently increased. To reinforce seismic capacity, spaced full-column-height steel bars are attached to column faces. In this study,nonlinear finite element analysis was conducted to analyze the effect of external reinforcement steel bars on the seismic capacity of RC columns with a square or rectangular cross-section. For verification, the analysis results were compared with test results. Results showed that the finite element analysis reasonably predicted the actual structural behavior of RC columns with steel bars. In addition, both the analysis and the test results showed that the failure mode was converted from brittle failure to ductile fracture, owing to the external reinforcement steel bars. Both loading capacity and ductility were increased as well. Therefore, the external reinforcement steel bar can effectively enhance the seismic capacity of existing RC columns. This study is expected to contribute to relevant research areas such as the development of design methods.

Reinforcement design for the anchorage of externally prestressed bridges with “tensile stress region”

C. Liu,B. Jung,G. Morgentha,D. Xu 사단법인 한국계산역학회 2013 Computers and Concrete, An International Journal Vol.11 No.5

Two-dimensional tensile stresses are occurring at the back of the anchorage of the tendons of prestressed concrete bridges. A new method named “tensile stress region” for the design of the reinforcement is presented in this paper. The basic idea of this approach is the division of an anchor block into several slices, which are described by the tensile stress region. The orthogonal reinforcing wire mesh can be designed in each slice to resist the tensile stresses. Additionally the sum of the depth of every slice defined by the tensile stress region is used to control the required length of the longitudinal reinforcement bars. An example for the reinforcement design of an anchorage block of an external prestressed concrete bridge is analyzed by means of the new presented method and a finite element model is established to compare the results. Furthermore the influence of the transverse and vertical prestressing on the ordinary reinforcement design is taken into account. The results show that the amount of reinforcement bars at the anchorage block is influenced by the layout of the transverse and the vertical prestressing tendons. Using the “tensile stress region” method, the ordinary reinforcement bars can be designed more precisely compared to the design codes, and arranged according to the stress state in every slice.

Different strengthening designs and material properties on bending behavior of externally reinforced concrete slab

Najafi, Saeed,Borzoo, Shahin Techno-Press 2022 Structural monitoring and maintenance Vol.9 No.3

This study investigates the bending behavior of a composite concrete slab roof with different methods of externally strengthing using steel plates and carbon fiber reinforced polymer (CFRP) strips. First, the concrete slab model which was reinforced with CFRP strips on the bottom surface of it is validated using experimental data, and then, using numerical modeling, 7 different models of square-shaped composite slab roofs are developed in ABAQUS software using the finite element modeling. Developed models include steel rebar reinforced concrete slab with variable thickness of CFRP and steel plates. Considering the control sample which has no external reinforcement, a set of 8 different reinforcement states has been investigated. Each of these 8 states is examined with 6 different uncertainties in terms of the properties of the materials in the construction of concrete slabs, which make 48 numerical models. In all models loading process is continued until complete failure occurs. The results from numerical investigations showed using the steel plates as an executive method for strengthening, the bending capacity of reinforced concrete slabs is increased in the ultimate bearing capacity of the slab by about 1.69 to 2.48 times. Also using CFRP strips, the increases in ultimate bearing capacity of the slab were about 1.61 to 2.36 times in different models with different material uncertainties.