• 한국지반공학회논문집
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• 제27권5호
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• pp.17-31
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• 2011

본 연구에서는 흙막이 굴착 공사시 지하수저하에 의한 주변 지반의 공학적 거동에 관한 수치해석 연구내용을 다루었다. 먼저 2차원 간극수압-응력 연계해석을 통하여 굴착공사가 지반침하 거동에 미지는 영향을 알아보았으며 그 결과를 토대로 벽체 수평변형, 벽체배변 변형, 소성변형률 분포, 유효응력분포 및 버팀보 축력분포 등을 분석을 수행하였다. 한편 다양한 지층조건과 초기 지하수위 조건에 대한 매개변수 연구를 통하여 주변지반 및 버팀보의 거동을 분석하였으며 해석 결과를 토대로 특정조건의 최대 지반변형범위를 제안하였다.

• Steel and Composite Structures
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• 제26권3호
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• pp.361-373
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• 2018

This paper presents the development of finite element (FE) models to simulate the behavior of diagonally stiffened steel plate shear wall systems (SPSWs) with differently shaped openings subjected to a cyclic load. This walling system has the potential to be used for shear elements that resist lateral loads in steel-framed buildings. A number of $\text\tiny{^1/_2}$-scale one-story buildings that were un-stiffened, stiffened and stiffened with opening SPSWs are modeled and simulated using the finite element method based on experimental data from previous research. After validating the finite element (FE) models, the effects of infill plate thickness on the cyclic behavior of steel shear walls are investigated. Furthermore, triple diagonal stiffeners are added to the steel infill plates of the SPSWs, and the effects are studied. Moreover, the effects of a number of differently shaped openings applied to the infill plate are studied. The results indicate that the bearing capacity and shear resistance are affected positively by increasing the infill plate thickness and by adding triple diagonal stiffeners. In addition, the cyclic behavior of SPSWs is improved, even with an opening in the SPSWs.

• 정보저장시스템학회논문집
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• 제2권3호
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• pp.201-207
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• 2006

Information storage devices have been studied to increase the storage capacity and the data transfer rate as well as to decrease the access time and their physical sizes. Optical information storage devices have been achieved high-capacity by reducing optical spot size remarkably due to the development of Blue-ray technology. Optical information storage devices usually use 1.2mm-thick polycarbonate(PC) media to get high enough stiffness. However, it would be better if we can decrease the thickness of a disk for achieving thinner device while keeping the capacity as large as possible. Decreasing the thickness of the storage media makes it difficult to read and write data because it increases the transverse vibration of the rotating disk due to the interaction with surrounding air and the vibration characteristics of thin flexible disk itself, Therefore, a special design based on the fluid mechanics is required to suppress the transverse vibration of the disk in non-contact manner so that the optical pickup can read/write data successfully. In this study, a curved wall is proposed as a stabilizer to suppress the transverse vibration of a $95{\mu}m$-thick PC disk. The characteristics of disk vibration due to a curved wall have been studied through numerical and experimental analysis from the fluid mechanics point of view. The proposed shapes are possible candidates as stabilizers to suppress the transverse vibration of a flexible disk which rotates at high speed.

• Earthquakes and Structures
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• 제23권1호
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• pp.59-73
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• 2022

In this study, the seismic behavior of an all-steel buckling-restrained (AB) steel plate shear wall (SPSW) with incline slits under fire and cyclic loading was investigated. ABSPSW was composed of two thin steel infill plates with a narrow distance from each other, which were embedded with incline slits on each plate. These slits were in opposite directions to each other. The finite element (FE) numerical model was validated with three test specimens and after ensuring the modeling strategy, the parametric study was performed by considering variables such as wall plate thickness, slit width, strip width between two slits, and degree of temperature. A total of 256 FE numerical models were subjected to coupled temperature-displacement analysis. The results of the analysis showed that the high temperature reduced the seismic performance of the ABSPSW so that at 917℃, the load-bearing capacity was reduced by 92%. In addition, with the increase in the temperature, the yield point of the infill plate and frame occurred in a small displacement. The average decrease in shear strength at 458℃, 642℃, and 917℃ was 18%, 46%, and 92%, respectively, compared to the shear strength at 20℃. Also, with increasing the temperature to 917℃, ductility increased by an average of 75%

• 한국지반공학회논문집
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• 제35권12호
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• pp.101-109
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• 2019

버켓작업대는 새롭게 개발되는 해상 구조물로서 교량기초 등의 시공을 위한 장비 및 인력의 임시 작업공간을 제공하는데 이용된다. 버켓작업대는 작업하중의 편심, 파도 및 바람의 수평하중 등에 의해 모멘트 하중이 작용한다. 그러므로, 본 연구에서는 3차원 유한요소 수치해석을 수행하여 버켓작업대의 모멘트 지지력을 산정하였다. 우선, 버켓에 대한 현장실험 결과와 비교하여 수치모델링의 적용성을 분석하였다. 그리고, 흙의 밀도, 버켓의 직경과 지중 근입깊이 등 다양한 조건에 대한 변수연구를 수행하였다. 지반조건은 균질한 사질토 조건을 적용하였으며 모멘트 하중은 지지대 상판의 중앙지점 회전각을 증가시켜면서 재하하였다. 모멘트-회전 해석결과로부터 모멘트 지지력을 산정한 결과 지지력이 버켓의 직경과 근입깊이에 영향을 받는 것으로 나타났다. 최종적으로 해석결과를 종합하여 버켓작업대의 예비설계를 위한 모멘트 지지력 예측식을 제안하였다.

• 자원환경지질
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• 제25권3호
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• pp.283-296
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• 1992

The Keumryeong deposits is a low grade copper deposits in which copper minerals form disseminated grains and thin veinlets in felsic volcanics seem to be dacite. Alteration of the volcanics consists mainly pervasive propylitization and silicification. Potassic alteration characterized by biotite developed locally adjacent to southwestern contact of granodiorite body. Principal sulfide minerals in altered zone are mainly pyrite and lesser chalcopyrite. Chalcopyrite content in potassic zone is relatively higher than that of surrounding propylitized zone. Pyrite and chalcopyrite accompanies magnetite, molybdenite, sphalerite, pyrrhotite, arsenopyrite, pentlandite, marcasite, hematite, ilmenite, rutile, bismuthinite and native Bi as disseminations, veinlets and knots. Granodiorite body is propylitized and contains veinlets of pyrite, chalcopyrite and molybdenite. Fluid inclusions in sulfide-bearing quartz veinlets and quartz grains of felsic volcanics and granodiorite in altered zone consist of liquid-rich, vapor-rich, $CO_2-bearing$ and halite-bearing inclusions. These four types of inclusion intimately associated on a microscopic scale and indicate condensing or boiling of ore fluid during mineralization. Homogenization temperature of coexisting fluid inclusions are mostly in the range of 350 to $450^{\circ}C$. High salinity fluid contains 28.6 to 48.4 weight percent NaCI equivalent and moderate salinity fluid cotains 0.5 to 12.5 weight percent NaCl equivalent. Pressure estimated from $CO_2$ mole fraction of $CO_2-bearing$ inclusion range 160 to 375 bars. The Kigu copper deposits is a fissure filling copper vein developed 500 m south from the Keumryong deposits. Mineralogy and fluid inclusion data of the Kigu deposits are similar to that of the Keumryeong deposits. Homogenization temperature of fluid inclusions from the Kigu deposits are reasonable agreement with temperature estimated from sulfidation curve of cubanite-chalcopyrite-pyrite-pyrrhotite and pyrite-pyrrhotite mineral assemblages. Not only mineral occurrence and wall rock alteration in the Keumryeong deposits but also fluid inclusion data such as temperature, salinity, pressure and boiling evidences are similar to those of porphyry copper deposits.

• Journal of the Korean Wood Science and Technology
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• 제37권6호
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• pp.524-530
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• 2009

기둥-보 구조와 경골목구조가 혼합된 공법은 경골목구조가 심벽 또는 평벽 요소로써 구조내력성능의 대부분을 차지하고 있다. 경골목구조의 수평전단내력성능은 면재에 대한 못접합부의 전단성능으로부터 예측할 수 있으며, 못접합부는 못의 휨내력성능을 이용하여 예측할 수 있다. 못접합에 의한 내력벽의 항복내력과 벽체 강성을 예측하기 위한 기초 연구로써 못의 휨내력성능을 이용한 못접합부의 항복내력 및 접합계수(초기강성)를 검토하였다. 못접합부 내력성능 예측에는 각각의 주부재에 대해 일반 지압내력 및 지압강성을 이용하고, 파스너인 나선형 철선못의 휨시험에 의한 휨항복내력성능을 이용하였다. 홈가공부의 지름에 의한 항복내력은 예측 정밀성이 우수하였으나, 접합계수는 낮게 예측되었다. 그 원인으로 주부재에서는 비중의 영향, 측면부재에서는 못머리지름에 의한 인발, 접합부에서는 못머리부의 지압 및 모멘트저항 등이 영향을 끼침을 알 수 있었으며, 이에 대한 차후 검토가 요구된다.

• Earthquakes and Structures
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• 제16권3호
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• pp.295-310
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• 2019

This study attempts to develop new simplified approximate formulas to predict the fundamental natural periods of vibration (T) for bearing wall systems engaged with special reinforced concrete shear walls (RCSW) under seismic loads. Commonly, seismic codes suggested empirical formulas established by regression analysis of measured T for buildings during earthquake motions. These formulas depend on structure type, building height, number, height and length of SW, and ratio of SW area to base area of structure. In this study, a parametric investigation is performed for T of 110 selected models of bearing RCSW systems with varying structural height, configuration of horizontal plans including building width, number and width of bays, presence of middle corridors and core SWs. For this purpose, a 3D non-linear response time history (TH) analysis is implemented using ETABS v16.2.1. New formulas to estimate T are anticipated and compared with those obtained from formulas of IBC 2012 and ASCE/SEI 7-10. Moreover, the study examines responses of an arbitrarily two selected test model of 60 m and 80 m in height with presence of SWs having middle corridors. It is observed that the performance of the tested buildings is different through arising of considerable errors when using codes' formulas for estimating T. Accordingly, using the present proposed formulas exhibits more reasonable and safer design compared to codes' formulas. The results showed that equitable enhancement is promising to improve T formulas approaching enhanced and accurate estimation of T with reliable analysis, design, and evaluation of bearing RCSW systems.

• Steel and Composite Structures
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• 제30권5호
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• pp.405-416
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• 2019

Profiled composite slab has been widely used in civil engineering due to its structural merits. The extension of this concept to the bearing wall forms the profiled composite wall, which consists of two external profiled steel plates and infill concrete. This paper investigates the structural behavior of this type of wall under axial compression. A series of compression tests on profiled composite walls consisting of varied types of profiled steel plate and edge confinement have been carried out. The test results are evaluated in terms of failure modes, load-axial displacement curves, strength index, ductility ratio, and load-strain response. It is found that the type of profiled steel plate has influence on the axial capacity and strength index, while edge confinement affects the failure mode and ductility. The test data are compared with the predictions by modern codes such as AISC 360, BS EN 1994-1-1, and CECS 159. It shows that BS EN 1994-1-1 and CECS 159 significantly overestimate the actual compressive capacity of profiled composite walls, while AISC 360 offers reasonable predictions. A method is then proposed, which takes into account the local buckling of profiled steel plates and the reduction in the concrete resistance due to profiling. The predictions show good correlation with the test results.

• Earthquakes and Structures
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• 제22권6호
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• pp.539-548
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• 2022

Steel plate shear walls (SPSWs) are one of the most important and widely used lateral load-bearing systems. The reason for this is easier execution than reinforced concrete (RC) shear walls, faster construction time, and lower final weight of the structure. However, the main drawback of SPSWs is premature buckling in low drift ratios, which affects the energy absorption capacity and global performance of the system. To address this problem, two groups of SPSWs under cyclic loading were investigated using the finite element method (FEM). In the first group, several series of circular rings have been used and in the second group, a new type of SPSW with concentric circular rings (CCRs) has been introduced. Numerous parameters include in yield stress of steel plate wall materials, steel panel thickness, and ring width were considered in nonlinear static analysis. At first, a three-dimensional (3D) numerical model was validated using three sets of laboratory SPSWs and the difference in results between numerical models and experimental specimens was less than 5% in all cases. The results of numerical models revealed that the full SPSW undergoes shear buckling at a drift ratio of 0.2% and its hysteresis behavior has a pinching in the middle part of load-drift ratio curve. Whereas, in the two categories of proposed SPSWs, the hysteresis behavior is complete and stable, and in most cases no capacity degradation of up to 6% drift ratio has been observed. Also, in most numerical models, the tangential stiffness remains almost constant in each cycle. Finally, for the innovative SPSW, a relationship was suggested to determine the shear capacity of the proposed steel wall relative to the wall slenderness coefficient.