• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.329-332
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• 2008

The member deflection is one of the most important considerations for the serviceability evaluation of reinforced concrete structures, and the concept of the effective moment of inertia has been generally used for the estimation of beam deflections. The KCI design code adopted Branson's equation for the calculation of the effective moment of inertia, which was formulated based on the results of beam tests subjected to uniformly distributed loads. Therefore, it is worthwhile to check the applicability of the code approach on the estimation of the effective moment of inertia for the cases of beams under different loading conditions. In this study, an experimental investigation has been conducted on six beams, where primary variables were concrete compressive strengths and loading distances from supports. The test results were compared with various approaches proposed by Branson and others as well. The test results indicated that the effective moment of inertia was somewhat influenced by the moment distribution shape. Despite the different moment distribution shapes for specimens, however, the effective moment of inertia of all test beams were closely predicted by the existing methods considered in this study.

• Journal of Korean Society of Steel Construction
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• v.17 no.4 s.77
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• pp.431-438
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• 2005

A steel-concrete composite column is a recently developed composite system in which the two opposite flanges of the H-shape section are connected by welded links, and the vacant space enclosed by the flanges, web, and links is filled with concrete. Previous experiments on the SC composite column were performed to evaluate its compression and bending and shear strengths, respectively, and they showed fairly good results. In addition to thesestudies, it may be necessary to evaluate the flexural-axial capacity of an SC composite column, because itscolumn members are generally subjected to axial force and bending moment at the same time. In this study, the bending strength of an SC composite column subjected to axial compression force was investigated experimentally. The results of the study showed that the AISC-LRFD provisions representedexcessively low values compared with those of the ACI, Eurocode-4, and Japan Code provisions. The Eurocode-4 provisions represented reasonable evaluations of the strength of the SC composite column composed of a non-compact section.

• Magazine of the Korea Concrete Institute
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• v.5 no.1
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• pp.103-113
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• 1993

일반적으로 스터럽이 없는 철근콘크리트 보의 전단강도는 콘크리트 압축강도, 주철근비, 전단스팬비 및 보 유효깊이에 좌우된다는 것이 많은 연구를 통하여 밝혀지고 있다. 따라서, 본 연구에서는 고강도 콘크리트를 사용한 철근콘크리트 보의 거동 및 전단강도 특성을 분석하기 위하여 주철근비, 전단스팬비 및 보 유효깊이를 변수로 두고 총 22개의 단철근 보 실험체를 제작하여 실험을 수행하였다. 실험결과는 ACI규준식, Zsutty식 및 Bazant & Kim식의 예측값들과 함께 비교, 분석되었는데, ACI 규준식은 주철근비 및 전단스팬비의 효과를 과소평가할 뿐만 아니라 유효깊이가 915mm인 큰 보의 경우 안전측이 아니어서 이에 대한 고려가 필요할 것으로 판단된다. Zsutty식은 주철근비의 효과를 적절하게 평가하는 것으로 나타났으며, Bazant & Kim 식은 유효깊이 증가에 따른 전단강도 감소 경향을 잘 예측하는 것으로 나타났다. 또한, 다른 연구자들의 실험치와 비교, 분석해본 결과 주철근비 및 전단스팬비의 효과는 콘크리트 압축강도 수준에 따라 큰 변화가 없는 것으로 판단된다.

• Journal of Advanced Marine Engineering and Technology
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• v.20 no.4
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• pp.59-69
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• 1996

냉동.공조 및 각종 화학공업에 널리 사용되는 열교환기인 응축기의 고성능화 및 합리적인 설계를 위해서는 냉매의 정확한 응축열전달률 예측과 그 메카니즘 규명이 필수 요건이다. 본 연구에서는 내경 9.7mm, 외경 12.7mm, 길이 1200mm의 수직 이중관 응축기의 압력강하 및 응축열전달특성을 실험적으로 밝혔다. 실험으로부터 Lockart-Martinelli의 상관 관계식을 이용한 수직 응축관내 압력강하 특성을 종래의 실험식들과 비교.검토하고 새로운 압력강하식을 제안하였다. 그리고 종래의 해석방법과는 달리 비환상류 모델을 가정한 해석결과로부터 전 유동양식에 걸쳐 적용할 수 있는 새로운 응축열전달 예측식을 제안하였다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.1
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• pp.1-8
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• 2017

A new empirical correlation was developed for application to the tandem tubes for saturated water at atmospheric pressure. The correlation was obtained by using experimental data and the least square method to calculate the bundle effect. A statistical analysis was performed to identify the suitability of the correlation. The correlation predicted the experimental data within ${\pm}8%$. The applicable ranges of the correlation correspond to a tube pitch of 28.5~114 mm, an elevation angle of $0^{\circ}{\sim}90^{\circ}$, an inclination angle of $0^{\circ}{\sim}90^{\circ}$, and heat fluxes of $0{\sim}120kW/m^2$ of the lower and upper tubes.

• Journal of the Korean Society of Hazard Mitigation
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• v.11 no.1
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• pp.93-99
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• 2011

In this study, a series of laboratory experiments are carried out to analyze fluid behaviors around multi-arranged (2 pieces) floating breakwaters with various parameters such as distance between structures, wave periods and steepness. The rate of wave transmission is shown to be affected directly by wave periods of incident waves and the breakwaters with multi-arranged structures show the highest rate of wave protection compared with other cases. The velocity fields around the breakwaters are measured by using the Laser Doppler Velocimetry system. The transmission coefficients are also measured in laboratory experiments. Finally, laboratory observed data are compared with numerical experimental results and analyzed in detail.

• Magazine of the Korea Concrete Institute
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• v.6 no.1
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• pp.111-119
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• 1994

The strength of vertical joints of precast concrete large panel structures depends on the many factors, such as the bond strength of grout concrete (or mortar), the interlocking of the shear keys, the dowel action of horizontal bars. Many experimental studies have been conducted to in vestigate the shear strength of the vertical joints. In domestic, a few design formulas to predict shear strength of the vertical joint were proposed by some investigators, but formulas were based on limited experimental results. The objective of this paper is to propose a suitable formula for the shear strength of vertical joints with 94 vertical joints experimental data using the modified Mohr-Coulomb's 4ield theory and regression analysis. From the comparison of the proposed formula with others, it is shown that the proposed formula can be used economically for the design of vertical joints.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.8
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• pp.606-616
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• 2011

The objectives of this study were to evaluate the applicability of adsorption models for adsorption properties of adsorbents. For this study, adsorption experiment of $NO_3^-$ ion using anion exchange resin has been investigated under adsorption equilibrium and kinetic in bach process. Adsorption equilibrium experiment were carried out that two conditions is change of adsorbate concentration and change of adsorbent weight. Experiment results have been analyzed by adsorption isotherm models, energy models and kinetic models. Under the condition of change of adsorbate concentration was best described by Sips and Redlich-Perterson isotherm models. However case of change of adsorbent weight was described by Langmuir isotherm models. It seems reasonable to assume that isotherm model was dominated by multiple mechanism according to experiment condition.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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• pp.753-757
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• 1996

연전식 제습기는 제습판과 발열판, 열전식 열펌프, 팬과 모타, 직류 전원공급 장치로구성되어 있으며, 열전식 열펌프에 직류전원을 공급하면 고온면과 저온면이 발생하는 데 저온면의 온도룰 로점온도 이하로 냉각하여 공기중에 있는 수분을 제거하는 원리를 이용한 것이다. 초기 단계로 개발된 열전식 열펌프를 이용한 열전식 제습기(TED-92)는 기계식 제습기에 비하 여 제습효율이 너무 낮기 때문에, 본 연구에서는 여러 문제점을 개선하는 방법으로 열전식 열펌 프의 선정, 핀 설계, 제습기의 설계 등을 중점적으로 개선하여열전식 제습기 (TED-95)를 개발하 였다. 여러가지 방법으로 실험한 결과, 열전식 열펌프 CP1.4-127-045L 2개를 사용하여 발열판의 크기를 300 mm로 하여 단열재를 사용하지 않고 입력 전류를 4A를 입력하였을 때 단위전력당 제 습량이 가장 많았다. 열전식 제습기와 기계식 제습기를 비교실험 해본 결과, 열전식 제습기가 기 계식 제습기에 비해 약 21%의 제습효율을 나타 내었다. 그러므로 초기의 열전식 제습기 (TED-92) 보다 약 2배의 제습효율을 높였다.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.1123-1127
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• 2005

종방향 유속의 연직분포 흐름 특성을 파악하기 위해서 중심각이 $180^{\circ}$인 단일 만곡부에서 실험을 수행하였다. 실험결과를 분석한 후 종방향 유속의 연직분포 흐름특성을 재현하기 위해서 원주형 종방향 운동 방정식에 와점성 개념을 도입하였다. Rozovskii의 종방향 그리고 연직방향 유속식들을 도입하여 이론식을 개발하였다. 이론식의 수리학적 변수들은 원심력 항, Chezy 계수, 그리고 전단유속 항들로 구성되어 있다. 이론식은 곡률반경을 따라 변화하는 만곡부 내에서 종방향 유속의 연직분포가 변형되는 현상을 재현하고 있다. 이론식은 본 연구에서 실험을 통해 취득한 관측자료와 비교한 결과 잘 일치함을 보여주고 있다.