• 한국강구조학회 논문집
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• 제29권6호
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• pp.435-442
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• 2017

모듈러 건축물을 중고층화하기 위해 횡력저항시스템은 반드시 필요한 구조 요소로 10~20층 규모에서 콘크리트 코어는 가장 전형적인 횡력저항시스템으로 알려져 있다. 습식 공법인 콘크리트 코어 공사는 모듈의 오염과 파손 가능성으로 모듈 적층과의 동시 작업이 곤란하다. 이에 모듈 적층과 콘크리트 코어의 동시 시공이 가능한 복합 PC 패널 공법을 개발하였다. 복합 PC 패널은 일정 간격을 두고 웨브가 마주보는 한 쌍의 C형강을 콘크리트 벽체의 상부와 하부에 결합한 구조 부재로 볼트로 접합하여 적층하는 건식 공법으로 콘크리트 코어를 구축할 수 있다. 이 연구에서는 복합 PC 패널이 콘크리트 벽체와 동등한 성능을 갖도록 해석을 통해 상세 개선 과정을 제시하였다.

• 한국농공학회지
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• 제39권4호
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• pp.90-97
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• 1997

Field inspections and laboratory tests for 31 agricultural reservoirs in Kyungki province were performed to provide basic data for maintenance and rehabilitation of agricultural reservoirs and to evaluate structural degradation of agricultural reservoirs Results of the study are as follows : 1) From survey's results of embankments, signs of settlement and lateral movement are appeared in 17 reservoirs. Crest settlement of 20~80cm, downstream settlement of 10~90cm, and 20~160cm lateral movement of embankments are detected from settlement and movement analysis of 17 reservoirs. Crest and downstream settlements and lateral movement are greatly occurred in 20 ~ 40 years after embankment construction. 2) About 39% of total reservoirs shows seepage problems occurred in the lower part of berm and retaining wall located between embankment and spillway. Probability of seepage problems is higher at retaining wall than others. 3) Concrete strength estimated by Schmidt hammer in structures of reservoirs is a range of 100~l50kgf/$cm^2$ and average deviation of concrete strength is about l0kgf/$cm^2$. Strength difference$({\delta}S)$ between compressive strength estimated by Schmidt hammer and uniaxial compressive strength of concrete core is about $\pm$100kgf/$cm^2$. This difference is due to absence or presence of reinforced bar in concrete core, variable length of concrete core and limitation of Schmidt hammer. 4) About 68% of total reservoirs shows leaching, 58% alkali-aggregate reaction and 71 % abrasion/frost. Leaching, alkali-aggregate reaction and abrasion/frost occurred in most reservoirs when passed 10 years after construction of structure parts.

• 비파괴검사학회지
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• 제24권6호
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• pp.566-572
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• 2004

금속성 도선 뿐 아니라 기상 또는 액상의 직류전류를 계측하기 위해서는 비접촉으로 전류를 측정할 필요가 있다. 본 논문은 직류전류를 비접촉으로 계측하기 위한 방법 중 하나로써 패러데이효과와 누설자속을 이용하는 방법을 제안하고, 이론적 고찰 및 실험적 검증결과를 보고한다. 공극을 가진 강자성체 코어를 1차 코일에 의하여 자화하면, 공극 주위에는 누설자속이 발생한다. 이러한 누설자속의 수직성분에 의하여 자기광학소자의 자구는 자화되어, 공극의 중심과 자벽은 평행하게 된다. 한편, 2차 코일에 의하여 자기광학소자에 수직한 방향으로 자장을 인가하면, 누설자속분포는 공극의 중심을 기준으로 좌우 대칭이었던 자구의 분포에 편향이 발생한다. 이때 금속, 기체 또는 액체상태의 전류가 코어를 통과하면 자기광학소자의 자벽이 이동하게 된다. 이러한 원리에 의하여 자구 또는 자벽의 이동량을 측정하면, 코어를 통과하는 직류전류의 세기를 알 수 있다.

• Journal of Advanced Marine Engineering and Technology
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• 제28권6호
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• pp.922-930
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• 2004

An experimental investigation was performed to study on the generation of air bubble and air core with swirling flow in a horizontal cicular tube. To determine some characteristics of the flow, 2D PIV technique is employed for velocity measurement in water. The experimental rig is manufactured from an acryl tube. The test tube diameter of 80mm, and a length of 3000mm. The used algorithm is the gray leve cross-correlation method(Kimura et al. 1986). An Ar-ion laser is used and the light from the laser(500mW) passes through a probe to make two-dimensional light sheet. In order to make coded images of the tracer particles on one frame, an AOM(Acoustic-Optical Modulator) is used. The maximum axial velocities showed near the test tube wall at y/D =0.1 and y/D =0.9 along the test tube. The higher Reynolds number increase, the lower axial velocities are showed in the center of the test tube. The air bubbles are generated from Re =10,000 and developed into air core from the recirculating water pump rpm equal 30Hz. The pressure and temperature are measured across the test tube at X/D=3.33.

• 한국자원식물학회:학술대회논문집
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• 한국자원식물학회 2018년도 추계학술대회
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• pp.68-68
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• 2018

A total of 47 core collections of pepper (Capsicum chinense Jacq.) conserved in National Agrobiodiversity Center (NAC) were studied under field condition at Jeonju. All accessions were characterized for their 14 qualitative and 16 quantitative characters. Results revealed that both qualitative and quantitative characters exhibited wide variation among the studied germplasm. Distribution of fruit characters (fruit length, width, and fruit wall thickness) among the accessions was positively skewed. Of the 47 accessions evaluated, 38.3% accessions had conical shaped fruits and mature fruit color was predominantly red (51.1%), orange (21.3%) and yellow (14.9%). Principal component analyses revealed that (i) 56.64% of the qualitative (fruit shape, color and fruit surface) variation and (ii) 89.42% of the quantitative (plant width, height and fruit maturity days) variation were explained by the first two components. Clustering revealed two groups and dendrogram revealed morphological variation among accessions. The phenotypic diversity exists in this core collections provide valuable information to improve agronomic traits in pepper breeding program.

• 국제초고층학회논문집
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• 제3권1호
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• pp.9-19
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• 2014

In this study the seismic performances of reinforced concrete apartment buildings with Y- and box-shaped plans having central core are investigated. Three types of model structures are designed for each shape depending on the amount of shear partition walls: structures with all shear walls, structures with all columns except the core walls, and structures with shear walls and columns combined. The required amount of concrete to satisfy the specified design loads is the largest in the all shear wall structures, and decreases as more and more shear walls are replaced with columns. The amount of re-bars increased significantly in the flat plate structures. According to nonlinear static and dynamic analysis results, the structures with all shear walls and all columns turn out to have the largest and the smallest strengths, respectively. However it is observed that even the all-column structures with shear core have proper load resisting capacity for design level seismic load.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 춘계학술대회논문집
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• pp.268-271
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• 2008

If a reactor vessel is failed to retain a molten corium in a postulated severe accident, the molten corium is released outside the reactor vessel into a reactor cavity. The molten corium would attack the concrete wall and basemat of the reactor cavity, which may lead to inevitable concrete decompositions and possible radiological releases. In the OECD/MCCI project, a series of tests were performed to secure the data for cooling the molten corium spread out at the reactor cavity and for the long-term CCI (Core Concrete Interaction). Also, a MCCI (Molten Core Concrete Interaction) analysis code, CORQUENCH was upgraded at Argonne National Laboratory with embedding the new models developed for the tests. This paper deals with analyses of MCCI at plant scale under the conditions of top flooding using the upgraded CORQUENCH code. The modeling approach is briefly summarized first, followed by presentation of a validation calculation that illustrates the predicative capability of the modeling tool. With this background in place, the model is then used to carry out a parametric set of scoping calculations that define approximate coolability envelopes for the LCS (Limestone Common Sand) concrete that has been evaluated in the OECD/MCCI project.

• 한국지진공학회논문집
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• 제25권6호
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• pp.251-259
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• 2021

Current seismic fragility functions for buildings were developed by defining damage state threshold based on story drift concerning foreign references and using the capacity spectrum method based on spectral displacement. In this study, insufficient details and dependence on the core location of piloti-type buildings were not reflected in the fragility function because it was developed before the Pohang earthquake. In order to develop an improved one for piloti-type buildings, several types of core were selected, damage state threshold was determined based on the capacity of structural members, and three-dimensional analyses were utilized. As a result, seismic fragility functions based on spectral acceleration were developed for various core locations and different shear strengths of the column stirrup. The fragility of piloti-type buildings significantly varied according to core location, an additional single wall, and whether the contribution of column stirrup was included or not. To estimate fragility more reasonably, it is necessary to prepare the parameters to reflect actual state well.

• 한국공간구조학회논문집
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• 제22권1호
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• pp.17-24
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• 2022

Currently, the construction trend of high-rise structures is changing from a cube-shaped box to a free-form. In the case of free-form structures, it is difficult to predict the behavior of the structure because it induces torsional deformation due to inclined columns and the eccentricity of the structure by the horizontal load. For this reason, it is essential to review the stability by considering the design variables at the design stage. In this paper, the position of the weak vertical member was analyzed by analyzing the behavior of the structure according to the change in the core position of the twisted high-rise structures. In the case of the shear wall, the shear force was found to be high in the order of proximity to the center of gravity of each floor of the structure. In the case of the column, the component force was generated by the axial force of the outermost beam, so the bending moment was concentrated on the inner column with no inclination.

• Structural Engineering and Mechanics
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• 제83권4호
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• pp.465-473
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• 2022

In this research, a numerical study has been provided for examining the nonlinear stability behaviors of sandwich beams having a cellular core and two face sheets made of nanocomposites. The nonlinear stability behaviors of the sandwich beam having geometrically perfect/imperfect shapes have been studied when it is subjected to a compressive buckling load. The nanocomposite face sheets are made of epoxy reinforced by graphene oxide powders (GOPs). Also, the core has the shape of a honeycomb with regular configuration. Using finite element method based on a higher-order deformation beam element, the system of equations of motions have been solved to derive the stability curves. Several parameters such as face sheet thickness, core wall thickness, graphene oxide amount and boundary conditions have remarkable influences on stability curves of geometrically perfect/imperfect sandwich beams.