• Advances in Energy Research
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• 제3권3호
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• pp.143-155
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• 2015

The Nile blue has been used as a photosensitizer with Arabinose as a reductant in photogalvanic cell for optimum conversion efficiency and storage capacity. Reduction cost of the photogalvanic cell for commercial utility. The generated photopotential and photocurrent are 816.0 mV and $330.0{\mu}A$ respectively. The maximum power of the cell is $269.30{\mu}W$ where as the observed power at power point is $91.28{\mu}W$. The observed conversion efficiency is 0.6095% and the fill factor 0.2566 has been experimentally found out at the power point of the photogalvanic cell, whereas the absolute value is 1.00. The photogalvanic cell so developed can work for 120.0 minutes in dark if it is irradiated for 200.0 minutes that is the storage capacity of photogalvanic cell is 60.00%. The effects of different parameters on the electrical output of the photogalvanic cell have been observed. A mechanism has also been proposed for the photogeneration of electrical energy.

• Steel and Composite Structures
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• 제22권1호
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• pp.141-159
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• 2016

Commonly in steel frames, steel beam and concrete slab are connected together by shear keys to work as a unit member which is called composite beam. When a composite beam is subjected to positive bending, flexural strength and stiffness of the beam can be increased due to "composite action". At the same time despite these advantages, composite action increases the strain at the beam bottom flange and it might affect beam plastic rotation capacity. This paper presents results of study on the rotation capacity of composite beam connected to Rectangular Hollow Section (RHS) column in the steel moment resisting frame buildings. Due to out-of-plane deformation of column flange, moment transfer efficiency of web connection is reduced and this results in reduction of beam plastic rotation capacity. In order to investigate the effects of width-to-thickness ratio (B/t) of RHS column on the rotation capacity of composite beam, cyclic loading tests were conducted on three full scale beam-to-column subassemblies. Detailed study on the different steel beam damages and concrete slab damages are presented. Experimental data showed the importance of this parameter of RHS column on the seismic behavior of composite beams. It is found that occurrence of severe concrete bearing crush at the face of RHS column of specimen with smaller width-to-thickness ratio resulted in considerable reduction on the rate of strain increase in the bottom flange. This behavior resulted in considerable improvement of rotation capacity of this specimen compared with composite and even bare steel beam connected to the RHS column with larger width-to-thickness ratio.

• 한국구조물진단유지관리공학회 논문집
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• 제2권3호
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• pp.205-211
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• 1998

The purpose of this study is to evaluate shear strengthening effects of R/C beams with carbon fiber sheets. The major variables are shear reinforcement ratios, CFS strengthening ratios and strengthening methods of CFS. Following conclusions can be extracted. The shear capacity of beam strengthened with CFS is about 32~87% higher than that of beams without shear reinforcement. The strengthening effects of patch type is larger than those of strip type. The strain distribution in CFS intersected with shear crack is similar to that in stirrup and larger strain is observed in the middle of the shear span. It can be estimated that shear strength reduction factor ${\alpha}$=0.3 is appropriate for peeling effect of CFS.

• 한국산학기술학회논문지
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• 제17권12호
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• pp.730-736
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• 2016

이전 연구에서 기존의 재하실험을 통한 교량의 공용 중 내하력 평가방법을 개선하기 위하여 충격계수 응답스펙트럼과 그에 따른 내하성능 변화 추정 방법이 제안되었다. 본 논문에서는 제안된 방법의 적용성을 검증하기 위하여 공용 중인 단순지지 단경간 교량에 대한 현장 동적특성 평가 실험을 수행하였다. 실험을 통해 상시 교통하중 상태에서 무선 가속도계를 이용하여 교량의 고유진동수 도출이 가능한 수준의 동특성 응답을 획득할 수 있었다. 대상 교량의 가속도 데이터로부터 동적거동은 1차 모드에 지배되며 준공 당시에 비해 공용 기간의 증가로 인해 고유진동수가 감소한 것으로 나타났다. 충격계수 응답스펙트럼으로부터 대상 교량의 발생 가능한 최대 충격계수를 추정하였다. 도출된 이전 및 현재의 고유진동수와 충격계수를 바탕으로 성능감소계수를 적용한 내하력 평가방법을 이용하여 성능변화를 추정하였다. 이전에 비해 공용내하력이 감소하였으나 설계 활하중을 상회하여 내하성능에는 문제가 없는 것으로 나타났다. 상시 교통하중 하에서의 가속도 계측 데이터와 충격계수 응답스펙트럼을 이용하는 제안된 내하성능 변화 추정 방법은 실제 교량에 적용 가능할 것으로 판단된다.

• 한국지반환경공학회 논문집
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• 제16권9호
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• pp.33-41
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• 2015

사질토 지반에 설치된 버킷기초의 수직지지력은 주면마찰력과 선단지지력의 합으로 산정할 수 있다. 하지만 수직하중 작용 시 나타나는 주면마찰력 감소와 선단지지력 증가의 특징을 정확하게 고려할 수 있는 설계식이 없으며, 실제와 같은 사질토 지반의 비관련흐름 특성이 반영되어야 한다. 본 연구에서는 2차원 축대칭 유한요소해석으로 사질토 지반에 설치된 원형 버킷기초의 수직지지력을 다양한 지반 마찰각과 기초 크기에 대하여 산정하였다. 해석 결과의 극한지지력을 주면마찰력과 선단지지력으로 분리하여 특징을 분석한 후 각각의 설계식을 도출하였다. 버킷기초의 주면마찰력은 선단지지력에 비해 크기가 매우 작고 말뚝 설계식과 차이가 근소하므로 이를 동일하게 사용하였다. 주면마찰력의 영향으로 얕은기초의 지지력보다 증가하는 버킷기초의 선단지지력은 기존의 설계식을 수정하여 적용할 수 있도록 해석 결과를 토대로 새로운 형상-깊이계수($s_q{\cdot}d_q$)를 제안하였다. 또한 관련흐름법칙을 적용하여 제안된 기존의 얕은기초 형상계수와 깊이계수는 실제 사질토 지반에서의 지지력을 과대예측하므로 비관련흐름 특성을 반영한 형상-깊이계수를 사용하여 지지력을 예측해야 한다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 봄 학술발표회 논문집
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• pp.845-850
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• 2001

The primary objective of this study is to develop the new equation that can predict the flexural strength of irregular walls by applying the concept of the effective width which is used in current codes. Results obtained from this data analysis are as follows : 1. It is conservative to use PCI provision and ACI code as the effective width for evaluating the flexural capacity of irregular walls 2. The result of this study shows that the Paulay & Priestley's proposition is available for more exactly and safely predicting flexural capacity of irregular walls throughout a reduction factor.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.347-348
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• 2006

Among various gear system, planetary gear system has the best characteristics in high efficiency, excellent strength capacity, easy convertible speed control, and compact design aspect. Strength of gear is considered as the most important design factor. We have studied tooth form and the planetary gear system that have high reduction gear ratio is created by using the involute curve.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 봄 학술발표회논문집(II)
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• pp.433-438
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• 1998

Design lateral strength calculated by current seismic design code is prescribed to be much lower than the force level required for a structure to respond elastically during design level earthquake ground motion. Present procedures for calculating seismic design forces are based on the use of elastic spectra reduced by a strength reduction factor known as "response modification factor, R". This factor accounts for the inherent ductility, overstrength, redundancy, and damping of a structural system. This study considers ductility and overstrength of the wall-type structure for investigating R factor. This means that R factor is determined from the product of "ductility-based R factor($R_$\mu$$) and overstrength factor($R_s$). $R_$\mu$$ factor is calibrated to attain the targer ductility ratio (system ductility capacity) and produced in the from of $R_$\mu$$ spectra considering the influence of target ductility, natural period, and hysteretic model. On the other hand, $R_s$ is more difficult to quantify, since it depends on both material and system-dependent uncertain parameters. In this study Rs factor was determined from the result of push-over analysis.-over analysis.

• 설비공학논문집
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• 제20권5호
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• pp.321-326
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• 2008

This paper presents and analyzes the effects of on-grid electricity cost, fuel price and initial capital cost of a CHP system, on the optimum DG and AC capacity and NPV, by using the ORNL CHP Capacity Optimizer, which was applied to a library in a university. By considering the current domestic energy cost and initial capital cost, it is shown that the installation and operation of the CHP system is not economical. However, with the current domestic CHP installation cost and fuel price, the NPV achieved by the installation of CHP system is greater when the on-grid electricity price is a factor of ${\times}1.5$ the present value. Regarding the initial capital cost of the CHP system, the reduction of the DG cost is much more economical than that of the AC cost, with respect to NPV. Electricity cost and fuel price have opposite effects on NPV, and NPV is more sensitive to an increase of the electricity cost than an increase of the fuel price.

• Nuclear Engineering and Technology
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• 제53권4호
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• pp.1331-1344
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• 2021

This study is to evaluate the seismic capacity of the fire-damaged cabinet facility in a nuclear power plant (NPP). A prototype of an electrical cabinet is modeled using OpenSees for the numerical simulation. To capture the nonlinear behavior of the cabinet, the constitutive law of the material model under the fire environment is considered. The experimental record from the impact hammer test is extracted trough the frequency-domain decomposition (FDD) method, which is used to verify the effectiveness of the numerical model through modal assurance criteria (MAC). Assuming different temperatures, the nonlinear time history analysis is conducted using a set of fifty earthquakes and the seismic outputs are investigated by the fragility analysis. To get a threshold of intensity measure, the Monte Carlo Simulation (MCS) is adopted for uncertainty reduction purposes. Finally, a capacity estimation model has been proposed through the investigation, which will be helpful for the engineer or NPP operator to evaluate the fire-damaged cabinet strength under seismic excitation. This capacity model is presented in terms of the High Confidence of Low Probability of Failure (HCLPF) point. The results are validated by the proper judgment and can be used to analyze the influences of fire on the electrical cabinet.