• Journal of the Korea institute for structural maintenance and inspection
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• v.3 no.1
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• pp.137-146
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• 1999

Analysis of R/C columns requires modeling of the plastic hinge region, as well as nonlinear material characteristics. This becomes a challenging task in view of the nonlinearity of both steel and concrete. Furthermore, formation and progression of plasticity in the hinge is a difficult phenomenan to simulate, especially under reversed cyclic loading and decaying strength conditions. This research provide one analytical model employed in column analysis, including the analysis procedure for establishing inelastic force-deformation relationships. The analytical results show good correlation with experimental data. The employed procedure with the adopted analytical models can be used to compute inelastic displacements of concrete columns with welded reinforcement grids. The inelastic deformability beyond the peak was similar to those indicated by columns with conventional ties. The superior performance of columns with welded grids may be attributed to the improved confinement characteristics of grids associated with increased rigidity of welded ties.

• Journal of the KSME
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• v.17 no.1
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• pp.40-44
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• 1977

먼저번에는(대한기계학회지 제16권 제4호 1976) 유한요소법의 중심부를 통하는 기본로선을 따라 가면서 기초 개념을 해설하였다. 이 해설에서 앞으로 취급될 사항은 다음과 같다. 1. 트러스 구조물의 정역학적 문제를 예제로 다루며 방향변환에 따르는 "변환매트릭스"해설 2. 기둥의 탄성 안정 문제를 예제로 다루며 비 선형 문제에서 등장하는 "추가 강성매트 릭스 (Incremental Stiffness Matrix)[N]의 해설 3. 1차원 문제에 있어서의 여러 가지 유한요소 해설 4. 2차원 문제에 있어서 평면형을 갖는 여러 가지 유한요소 해설 5. 2차원 문제에 있어서 곡면형을 갖는 여러 가지 유한요소 해설 6. 유한요소법의 발전 전망 7. 전자계산기 프로그래밍에 있어서의 여러문제 해설의 대상자는 공과대학 기계계열의 상급학년 학생 또는 고체역학 부문에 경력을 갖는 기술자 들로서 이 부문의 기본지식을 갖고 있는 자로 한다. 이번회에는 유한요소의 자유도 즉 미지상 수로 다루어지는 자변수의 좌표축이 바뀔 때 부수적으로 등장하는 변환 매트릭스에 대하여 해 설한다.트릭스에 대하여 해 설한다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.6 no.4
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• pp.243-254
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• 2002

This study investigates the structural behavior of cracked or uncracked RC columns retrofitted with CFS and evaluates the shear retrofit performance through experiment. Experimental works were conducted for sixth specimens varied in the adhesion method of CFS, the ratio of shear reinforcement bar, and the existence of crack before retrofitting. Throughout cyclic test, the strength, stiffness, failure modes, and ductility are discussed. The test results show that the retrofitting method with CFS improve the shear strength and ductility. The crack width below 2mm, occurred before retrofitting, didn't reduce the shear strengthening effect.

• Journal of The Korean Society of Grassland and Forage Science
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• v.37 no.1
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• pp.68-79
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• 2017

The objective of study was to find the relationship in hilly pasture landscape expectancy and tourist's satisfaction on grassland facility. It was followed by literature reviews and visitors' survey in Daegwallyeong Yangtte Farm on 31, July, 2014. 367 respondents were analyzed by F-test, t-test, Chi-square and Fisher's Exact Test at 0.05 level after data screening process. Computing factors were sex, marital status, age, academic career and occupation. The results was as followed; First, major respondents group of survey were in oder of woman, forty years old group, married office worker, and university graduate. Second, the expectancy for grassland was significant difference in age, but pasture color expectancy was not significant difference in gender, age, educational background, marital status, and there was significant difference in favorite grassland type with age, marital status. Third, favorite fence type was not significant difference along with all group of participants. However, color and material of fence was significant difference in marital status. Fourth, preferred ranch road was significant difference with occupation and marital status. There was significant difference in favorite grassland type near ranch road along with age and occupation type. Fifth, the mean satisfaction was 3.6 point in 5.0. Therefore, all respondents were generally satisfaction in visited. Tourists were more interested in ranch landscape than experience or contacts to animal.

• Journal of the Earthquake Engineering Society of Korea
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• v.9 no.5 s.45
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• pp.53-61
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• 2005

In order to evaluate the limit earthquake resistance of multi-story steel frames influenced by the strength and stiffness ratios of members, a series inelastic response analysis were carried out. From the analysis results, the damage distribution rules of multi-story steel frames were proposed. Conclusions are summarized as follows; 1)As the stiffness ratios of beam and column becomes small, the damage concentrates on the lower end of columns of the first story. 2) Considering the strength and stiffness ratios of the beam and column with weak beam type mechanism, the equations predicting the damage distribution of multi-story steel flames were proposed. 3) Through the equation which was supposed in this study, it is speculated that the damage distribution of the rigid or semirigid beam collapse type multi-story steel structure building can be predicted.

• Journal of Advanced Navigation Technology
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• v.21 no.6
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• pp.614-619
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• 2017

In this paper, we optimize the wireless power transmission (WPT) coil, and then compare the EM simulation and measurement using magnetic coupling at 6.78 MHz. As transmission efficiency is affected by various factors such as the shape of the system, the size of the coils, the coil structure is proposed to consist of a helical resonant for transmission and a spiral resonant for reception. The size of the coil and the distance between the coils are determined to minimize the volume problem, and the shape of the coil are confirmed by EM simulation. A WPT system is designed with 860mm diameter top plate and cylindrical structure of column spaced 600mm apart, and the characteristics are simulated and measured. The simulation shows that ${\mid}S_{21}{\mid}$ is -0.53 dB with the efficiency of 88%, and the measurement result is that ${\mid}S_{21}{\mid}$ is -0.71 dB with the efficiency of 85%.

• Composites Research
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• v.34 no.4
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• pp.257-263
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• 2021

Composite materials have been widely applied for fabricating pressure vessels used for storing gaseous and liquid fuel because of their high specific stiffness and specific strength. Accordingly, the accurate measurement of their mechanical property, particularly the burst pressure or fracture strain, is essential prior to the commercial release. However, verification of the safety of composite pressure vessels using conventional test methods poses some limitations because it may lead to the deformation of the load transferring media or provoke an additional energy loss that cannot be ignored. Therefore, in this study, the segment-type ring burst test device was designed considering the theoretical load transferring ratio and applicable displacement of the vertical column. Moreover, to verifying the uniform distribution of pressure of the segment type ring burst test device, the hoop stress and strain distribution of ring specimens were compared with that of the hydraulic pressure test method via FEM. To conduct a simulation of the fracture behavior of the composite pressure vessel, a Hashin failure criterion was applied to the ring specimen. Furthermore, the fracture strain was also measured from the experiment and compared with that of the result from the FEM.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.5
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• pp.111-118
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• 2020

The U-shaped composite beam used in this study consist of a reinforced concrete structure, a beam steel structure supporting the slab, a reinforced concrete structure, and a U-shaped steel plate. The U-shaped composite beam was developed for the purpose of using it as a parking lot because it is highly constructible and has low floor height and long span. For the improvement of constructivity, the U-shaped composite beam ends are planned with standardized H-shaped steel and connected directly to the columns, and the middle of the U-shaped composite beam consists of U-shaped steel plates folded in U-shaped form using thin steel plates (t=6) instead of H-shaped steel. In the middle of the composite beam, where U-shaped steel plates are located, the depth of U-shaped beam may be planned to be small so as to satisfy the height limit of the parking lot. It is important to grasp the structural performance according to the change of depth because low beam depth is advantageous for the reduction of the floor height, but it is a inhibitor to the structural behaviors of U-shaped composite beam. In addition, since U-shaped composite beams are a mixture of steel frame structures, reinforced concrete structures and U-shaped steel plates, securing unity has a great influence on securing structural performance. Therefore, in this study, a structural experiment was conducted to understand the structural performance according to the depth change for U-shaped composite beam. A total of three specimens were planned, including two specimens that changed the depth using a criteria specimen planned for a general parking lot. The results of the experiment showed that the specimens who planned the depth greatly had better structural performance such as yield strength, maximum strength, and energy than the standard specimen.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.21 no.6
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• pp.253-258
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• 2011

Electro-mechanical coupling performance ($k_t$) of a 1-3 type Piezo-composite was analyzed numerically using FEM. The calculated physical properties of the PZT ceramics were compared with the experimental data and the accuracy of the numerical method was verified. Also the $k_t$ of the composite was analyzed with the vol% and the material properties of the constitutional parts, and the aspect ratio of the PZT rod. As the simulated results, the $k_t$ increased rapidly when the vol% of the PZT ceramics increased up to 30 vol% and saturated the constant value in the above region. And the composite using the soft matrix polymer than the hard one have the superior $k_t$ characteristics. The $k_t$ was greatly influenced by the aspect ratio of the PZT rod up to 30 vol% of PZT ceramics. To improve the $k_t$ characteristics, it is useful that the composite consist of the relatively flexible polymers and the PZT material having the excellent piezoelectric characteristics.

• Journal of the Korean earth science society
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• v.28 no.1
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• pp.54-63
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• 2007

The sedimentary sequence of the non-marine Cretaceous Jinju Formation from Sacheon, Korea, contains a number of rod-shaped stromatolites (RSS) characterized by concentric lamination with curd-shaped, stratiform, and small columnar stromatolites. Unlike the world trend, a massive distribution of rod-shaped stomatolite was discovered in the region. The mineral composition, diagenetic alteration, and weathering process of the kind were analyzed by EPMA. The gross morphology of RSS is almost identical to broken plant twigs or stems formed by microbial activity onto which it grew. RSSs are interpreted as stromatolitic algae over plant twigs, which formed through concentric carbonate precipitation by epiphytic algal photosynthesis. The distribution of localities and horizons of the stromatolite imply that RSS is allochthonous and autochthonous. Two types of cyanobacterial filaments and one type of peen algal filament were discovered. The size frequency distribution of calcified filamentous microfossils found in stromatolite was $2.2{\mu}m\;and\;7.8{\mu}m$ in mean diameter of the former, $32.3{\mu}m$ in mean diameter of the latter. The cyanobacterial fossils played a key role in the formation of stromatolite, while the green algal filament was auxiliary stromatolite-builder stromatolites. The filamentous microfossils including trichome were found within the stromatolitic laminae.