• 한국도로학회논문집
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• 제8권4호
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• pp.115-124
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• 2006

본 논문의 목적은 Falling Weight Deflectometer 처짐값을 이용하여 아스팔트 포장체의 구조적 상태 평가기법을 개발하고, 이를 이용하여 포장체 각 층의 구조적 상태 평가기준을 제시함에 있다. 유한요소해석 아스팔트 포장체 구조해석 프로그램을 이용하여 가상적 데이터베이스를 구축하여 포장체의 표면처짐값과 포장체 내부반응과의 상관관계를 도출하였다. FWD 처짐값과 포장체 두께를 이용하여 직접적으로 포장체 내부반응을 계산할 수 있는 아스팔트 포장체의 내부반응 모델을 통계적 회귀분석을 통하여 개발하였다. 개발된 반응모델을 토대로 아스팔트 포장체 각 층의 구조적 상태를 평가하기 위한 절차를 제시하였다. 본 연구에서 제시한 평가 절차를 검증하기 위하여 국도 11개와 지방도 8개 노선에서 FWD와 동적관입시험을 수행하였으며, 현장에서 채취한 코어는 아스팔트 시편의 삼축압축반복재하시험을 수행하였다. 연구결과, 아스팔트층의 경우 아스팔트층 하부의 인장변형률값과 회복탄성계수값이 아스팔트 층의 강성 특성을 평가하는 중요한 인자로 판단되었다. 보조기층에서는 BDI값과 보조기층 상부의 압축변형률이 보조기층의 지지력 평가에 적합하였으며, 하부층의 경우 BCI값과 하부층 상부의 압축변형률값이 노상토의 지지력 및 상태를 판단하는데 적절한 인자로 선정되었다. 아스팔트층과 보조기층은 3단계, 하부층은 2단계로 구분하여 아스팔트 포장체의 구조적 상태를 평가 할 수 있는 기준을 제시하였다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2021년도 봄 학술논문 발표대회
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• pp.100-101
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• 2021

Facilities with high risk of a disaster or requiring continuous safety management are designated as class-III facility. In order to designate a class-III facility, it is evaluated based on the safety status of the facility, the risk to the building users, and the number of years elapsed of the facility, etc. and this shall be referred to the actual condition survey for the designation of a class-III facility. In the actual condition survey conducted to designate the safety status is calculated by the checklist based on the evaluation scores consisting of five stages each item, and is evaluated in three stages by 'good', 'careful observation', and 'designated review' through the average of the combined scores. Currently, the actual condition survey being conducted applies only structural stability, and the risk factors such as damage to the finish, the risk of cracking, and the type and weight of major structures are not included in the checklist for the actual condition survey, so even if experts think it is dangerous, scores cannot be reflected. Therefore, this study aims to analyze the problems of checklist of the actual condition survey for the designation of class-III facility and to propose an improvement plan for the checklist for the actual condition survey.

• International Journal of Concrete Structures and Materials
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• 제9권4호
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• pp.427-438
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• 2015

The present work proposes a new image analysis method for the evaluation of the multi-walled carbon nanotube (MWNT) distribution in a cement matrix. In this method, white cement was used instead of ordinary Portland cement with MWNT in an effort to differentiate MWNT from the cement matrix. In addition, MWNT-embedded cement composites were fabricated under different flows of fresh composite mixtures, incorporating a constant MWNT content (0.6 wt%) to verify correlation between the MWNT distribution and flow. The image analysis demonstrated that the MWNT distribution was significantly enhanced in the composites fabricated under a low flow condition, and DC conductivity results revealed the dramatic increase in the conductivity of the composites fabricated under the same condition, which supported the image analysis results. The composites were also prepared under the low flow condition (114 mm < flow < 126 mm), incorporating various MWNT contents. The image analysis of the composites revealed an increase in the planar occupation ratio of MWNT, and DC conductivity results exhibited dramatic increase in the conductivity (percolation phenomena) as the MWNT content increased. The image analysis and DC conductivity results indicated that fabrication of the composites under the low flow condition was an effective way to enhance the MWNT distribution.

• 대한인간공학회지
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• 제29권1호
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• pp.121-128
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• 2010

The purpose of this study is to confirm the impact of noise on subject accomplishment as well as physical/mental load, and evaluates the effects of noise-masking and earplug. 15 college students participate in the test, and the comparison is performed by executing four projects according to conditional categories of noise environments; control condition, noise condition, earplug condition, and noise-masking condition. Noise in the field site of the H manufacturer was used as the noise source, the general job aptitude test which consist of linguistic ability, math ability, perception ability, reasoning ability was used as the task of this project. To estimate physical/mental load evaluation, we used the heart rate R-R interval, Criteria flicker fusion frequency(CFF) and measured NASA-TLX workload for subjective evaluation. As the research outcome, it is shown that there is a meaningful difference for the project task score, dropping rate of CFF, the heart rate, and NASA-TLX subjective evaluation score according to conditions of noise environment. Therefore, the impact of noise on capability of subject accomplishment as well as physical/mental load was confirmed along with the effects of using earplug and noise-masking.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2005년도 전기학술대회논문집
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• pp.382-387
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• 2005

An electrochemical evaluation on the corrosion resistance for heavy anticorrosive paint was carried out for 5 kinds of heavy anticorrosive paints such as High solid epoxy(HE), Solvent epoxy(SE), Tar epoxy(TE), Phenol epoxy(PE), and Ceramic epoxy(CE) as parameters of DFT(Dry Film Thickness, 25${\mu}m$50${\mu}m$, solution condition(Flow of Nonflow). Corrosion current density of HE(DFT 50${\mu}m$ in case of flow condition was larger than that of nonflow condition. However, their values of the other anticorrosive paints were decreased compared to the nonflow condition. The values of AC impedance were increased with increasing of DFT regardless of kinds of anticorrosive paints. And the polarization resistance of cyclic voltammogram showed a good tendency to correspond with well the values of AC impedance measurement. HE and CE had a relatively good corrosion resistance than other heavy anticorrosive paint.

• 한국환경복원기술학회지
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• 제8권6호
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• pp.45-58
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• 2005

The objective of this study is to the integrated evaluation of the present condition and satisfaction of visitors of rooftop greening area using quantitative and qualitative method. The thirteen green roofs were selected to investigate environmental variables as like building structure, soil, water, atmosphere and climate environment and questionnaire survey for investigate the satisfaction of visitors was conducted. The results of this study are as follows : remove of the hazardous inflow of species, install rain water recycling facility, install outdoor unit of air condition where not to affect plants in green roof, install safety facilities in the case of making resting place, plant variable vegetation and so on. The result of questionnaire survey are that visitors want to make more comfortable resting space. The more bigger the resting space and privacy, the more satisfaction of visitor became high. In conclusion, green roofs implementation should be considered reduction of temperature and delay of runoff, insulation effect and ecological restoration as well as rooftop greening is focused on the development of resting space nowadays.

• 한국정보통신학회논문지
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• 제17권12호
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• pp.3030-3037
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• 2013

위성통신설비의 수명은 설비별 사용빈도와 운영환경에 따라 상이하나, 설비 개대체시 내용년수만을 고려하고 있는 실정이다. 따라서, 설비의 성능분석을 통한 상태평가 및 의사결정에 따른 과학적 근거를 기초로 한 경제적인 자산관리가 필요하다. 본 연구에서는 K-water에서 사용하고 있는 위성통신설비에 대하여 물리적 평가, 성능분석 평가, 경제성 평가, 내용년수 평가를 통한 과학적인 상태평가표를 제안하였으며, 이를 통한 합리적인 개대체 방안을 수립하였다.

• 한국안전학회지
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• 제30권5호
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• pp.131-137
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• 2015

For the evaluation of safety margin of a nuclear power plant using a conservative methodology, the influence of applied assumptions such as initial conditions and boundary conditions needs to be assessed deliberately. Usually, a combination of the most conservative initial conditions is determined, and the safety margin for the transient is evaluated through the analysis for this conservative conditions. In existing conservative methodologies, a most-conservative condition is searched through the analyses for the maximum, minimum, and nominal values of the major parameters. In the present study, we investigates a new approach which can be applied to choose a most-conservative initial condition effectively when a best-estimate computer code and a conservative evaluation methodology are utilized for the evaluation of safety margin of transients. By constituting the band of various initial conditions using the random sampling of input parameters, the sensitivity study for various parameters are performed systematically. A method of sampling the value of control or operation parameters for a certain range is adopted by use of MOSAIQUE program, which enables to minimize the efforts for achieving the steady-state for various different conditions. A representative control parameter is identified, which governs the reactor coolant flow rate, pressurizer pressure, pressurizer level, and steam generator level, respectively. It is shown that an appropriate distribution of input parameter is obtained by adjusting the range and distribution of the control parameter.

• 한국안전학회지
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• 제32권2호
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• pp.98-104
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• 2017

The ultrasonic pulse velocities of pressure, shear, and Rayleigh waves ( P-, S-, and R- waves) have been used for the condition evaluation of various concrete structures, but the statistical distribution according to the wave type has not been studied clearly in view of data reliability and validity. Therefore, this study analyzed the statistical distribution of P-, S-, R-wave velocities in concrete wide beams of $800{\times}3100mm$ (width ${\times}$ length) with a thickness of 300 mm. In addition, we investigated an experimental consistency by the Kolmogorov-Smirnov goodness-of-fit test. The experimental data showed that the R-, S- and P- wave velocities in order have better statistical stability and reliability for in situ evaluation because R- and S-waves are less sensitive to confinement and boundary conditions. Also, good correlations between wave velocities and strength and modulus of elasticity were found, which indicate them as appropriate techniques for estimating the mechanical properties.

• 에너지공학
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• 제17권4호
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• pp.212-217
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• 2008

본 연구는 이동식 부탄연소기에 사용되는 1회용 부탄캔의 변형 및 폭발을 방지하기 위하여, 캔에 안전밸브를 장착한 폭발방지 부탄캔에 대한 사용 중 안전성을 평가하였다. 실제 사용환경에서 설계압력의 오차 범위 내에서 안전밸브가 작동하는지, 안전밸브의 분출유량은 캔의 변형 및 폭발을 방지하기에 적정하게 설계되었는지, 그리고 안전밸브 작동으로 인하여 가스가 누출되었을 때 주변의 점화원에 의한 화재 및 폭발의 위험성 등을 평가하였다. 본 연구를 통해 개발제품이 외부열원에 의한 부탄캔의 내압상승을 방지하여 캔의 폭발을 방지하는 것으로 평가되었다.