• 한국환경과학회지
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• 제24권11호
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• pp.1451-1461
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• 2015

The purpose of this study is to describe how nature-based ecotourism motivation of ecotourists influences destination image and satisfaction of ecotourists. In order to achieve the above purposes, the study carried out a literature study and an empirical analysis. Based on the obtained data through the literature study, the study designed a model for the empirical study. The results of this study are as follows. First, returns to nature, knowledge. fitness and escape as ecotourism motivation of ecotourist had a positive effect on each ecotourism destination image, such as cognitive and affective image. However, effect of novelty on cognitive image for destination had not significant results. Second, ecotourism destination image, such as cognitive and affective image, had a positive effect on ecotourism satisfaction of ecotourists. The results of the article provide implications for strategies for promoting ecotourism destination and suggest some guidelines for the eco-education of tourists.

• 혜화의학회지
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• 제22권2호
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• pp.143-154
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• 2014

Objective : The purpose of this study is to establish a concept called as 'medical service' newly and to develop an reliable and valid scale that measures medical service. Methods : In order to accomplish these objectives, both conceptual study and empirical study were performed. In a conceptual study, 5 core factors(doctor, medical team, medical facilities, medical process, and hospital) and 24 sub factors were extracted with assistant by 7 experts, based on antecedent studies about components of medical service. In an empirical study, data was taken from 244 adults living in Seoul and Daejeon with the conceptually founded medical service scale. Results : Results of empirical study showed reliability and validity of the medical service scale. Internal consistency coefficient showed high score of .97 and, in accordance with the conceptual study, "medical treatment factor", "appearance factor", "personal factor", "trust factor" and "dissatisfaction factor" were extracted from the data as the five main factors. Conclusions : Finally, limitations of this study and directions for further studies are discussed. Acknowledgement : This work was supported by the Daejeon University Research Grant.

• 터널과지하공간
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• 제13권4호
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• pp.260-269
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• 2003

In order to introduce to engineers the suitable calculation techniques of TBM advance rate (ad.) and ultimately promote to understand the designing process, this study was carried out. We analyzed the 17 bored data of TBM which applied to the roadway and water supply tunnels in Korea. From this analysis, it was able to how that the average utilization is 30.83% md the correlation equation of Ad and TBM´s diameter (D) is Ad(m/month) = 506.05ㆍ $e^{-0.1162}$$\times$D than the correlation coefficient ($R^2$) is 0.76. In the object of the W tunnel of Seoul-Busan highspeed railway, the Ad of TBM 5.0mø was analyzed by the variety of empirical models and upper correlation equation. Average Ad of the empirical models was calculated to be larger than one of the upper equations. But considering only the results of 3.0~5.0mø TBM in the 17 bored data, the average Ad by the models belongs to the similar range of bored data. Therefore, when the reliability and representative of parameters are decreased, a reliability test should be carried out through the comparison a variety of empirical models with the upper correlation equation.

• Structural Engineering and Mechanics
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• 제68권2호
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• pp.247-259
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• 2018

In this study (Part I), an advanced empirical formulation was proposed to predict the ultimate strength of initially deflected steel plate subjected to longitudinal compression. An advanced empirical formulation was proposed by adopting Initial Deflection Index (IDI) concept for plate element which is a function of plate slenderness ratio (${\beta}$) and coefficient of initial deflection. In case of initial deflection, buckling mode shape, which is mostly assumed type in the ships and offshore industry, was adopted. For the numerical simulation by ANSYS nonlinear finite element method (NLFEM), with a total of seven hundred 700 plate scenarios, including the combination of one hundred (100) cases of plate slenderness ratios with seven (7) representative initial deflection coefficients, were selected based on obtained probability density distributions of plate element from collected commercial ships. The obtained empirical formulation showed good agreement ($R^2=0.99$) with numerical simulation results. The obtained outcome with proposed procedure will be very useful in predicting the ultimate strength performance of plate element subjected to longitudinal compression.

• 한국철도학회논문집
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• 제12권3호
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• pp.357-363
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• 2009

본 논문에서는 도시철도 운행으로 발생하는 지반진동의 예측을 위하여 서울지하철 현장 계측을 실시하였다. 현장 계측 결과와 뉴욕지하철의 예측식과 동경지하철의 예측식으로 산정된 값과 비교한 결과, 국내 지반의 지반진동레벨은 뉴욕지하철의 예측식보다 크게 산정되었으며, 동경지하철의 예측식보다는 다소 작게 산정되었다. 또한, 계측현장 지반의 전파경로에 따라 토사지반과 암반지반으로 구분하여 국내 지반특성에 적합한 지반진동 예측식을 제안하였다.

• 한국도로학회논문집
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• 제16권1호
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• pp.57-62
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• 2014

PURPOSES : Capacity is a main factor of determining the number of lane in highway design or the level of service in road on operation. Previous studies showed that breakdown may occur before capacity is reached, and then it was concluded that capacity is a stochastic value rather than a deterministic one. In general, estimating capacity is based on average over maximum traffic volume observed for capacity state. This method includes the empirical distribution method(EDM) and would underestimate capacity. This study estimated existing empirical methods of estimating stochastic highway capacity. Among the studied methods are the product limit method(PLM) and the selected method(SM). METHODS : Speed and volume data were collected at three freeway bottleneck sites in Cheonan-Nonsan and West Sea Freeway. The data were grouped into a free-flow state or capacity state with speeds observed in the bottlenecks and the upstream. The data were applied to the empirical methods. RESULTS : The results show that the PLM and SM estimated capacity higher than EDM. The reason is that while the EDM is based on capacity observations only, the PLM and SM are based on free-flow high volumes and capacity observations. CONCLUSIONS : The PLM and SM using both free-flow and capacity observations would be improved to enhance the reliability of the capacity estimation.

• 공업화학
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• 제29권6호
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• pp.789-798
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• 2018

고분자전해질 연료전지(PEMFC)의 성능을 예측할 수 있는 empirical equation의 역할이 중요하게 대두되고 있다. 본 연구에서는 polarization curve에서 activation loss, ohmic loss, mass transfer loss 영역을 분리하였고, 현재까지 개발된 model 중 Kim의 model과 Hao의 model을 선정하여 각 영역의 fitting을 시행하였다. 온도, 압력, 산소 농도 및 막 두께를 운전변수로 설정하여 조건 변화에 대한 각 loss의 변화를 비교하였다. 기존 model은 전반적으로 좋은 fitting 정확도를 보였지만, 분리된 loss 영역에서는 부정확한 fitting 결과를 보이기도 하였다. 연료전지 성능 예측의 정확도를 개선하기 위하여 converge coefficient를 도입한 새로운 model을 제안하였다. 본 연구에서 제안한 model을 연료전지 성능 예측에 적용한 경우에 신뢰도 평가에서 개선된 결과를 얻을 수 있었다.

• Computers and Concrete
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• 제26권6호
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• pp.533-546
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• 2020

The prediction of spall response of reinforced concrete members like columns and slabs have been attempted by earlier researchers with analytical solutions, as well as with empirical models developed from data generated from physical or numerical experiments, with different degrees of success. In this article, compared to the empirical models, more versatile and accurate models are developed based on model-free approach of artificial neural network (ANN). Synthetic data extracted from the results of numerical experiments from literature have been utilized for the purpose of training and testing of the ANN models. For two concrete members, namely, slabs and columns, different sets of ANN models were developed, each of which proved to have definite advantages over the corresponding empirical model reported in literature. In case of slabs, for all three categories of spall, the ANN model results were superior to the empirical models as evaluated by the various performance metrics, such as correlation, root mean square error, mean absolute error, maximum overestimation and maximum underestimation. The ANN models for each category of column spall could handle three variables together: namely, depth, spacing of longitudinal and transverse reinforcement, as contrasted to the empirical models that handled one variable at a time, and at the same time yielded comparable performance. The application of the ANN models for spall prediction of concrete slabs and columns developed in this study has been discussed along with their limitations.

• 한국방재안전학회논문집
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• 제15권1호
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• pp.35-46
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• 2022

본 연구에서는 토석류 피해 발생지역에 대해 토사유출량 산정에 많이 사용되고 있는 RUSLE와 NILIM 그리고 Marchi의 경험식을 통해 토사유출량을 산정하였으며, 토사유출량 산정 방법의 국내 적용성을 검토하기 위해 정밀측량 및 현장조사를 통해 측정된 토사유출량을 비교하였다. RUSLE 방법은 실측 토사유출량에 비해 평균 2.13배 과다 산정되었으며, Marchi의 경험식은 평균 2.83배, NILIM 경험식의 경우 평균 1.26배로 세 가지 경험식 중 가장 낮은 오차가 발생하였다.

• Nuclear Engineering and Technology
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• 제54권11호
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• pp.4159-4169
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• 2022

Hydrogen mitigation using Passive Autocatalytic Recombiners (PARs) has been widely accepted methodology inside reactor containment of accident struck Nuclear Power Plants. They reduce hydrogen concentration inside reactor containment by recombining it with oxygen from containment air on catalyst surfaces at ambient temperatures. Exothermic heat of reaction drives the product steam upwards, establishing natural convection around PAR, thus invoking homogenisation inside containment. CFD models resolving individual catalyst plate channels of PAR provide good insight about temperature and hydrogen recombination. But very thin catalyst plates compared to large dimensions of the enclosures involved result in intensive calculations. Hence, empirical correlations specific to PARs being modelled are often used in integral containment studies. In this work, an experimentally validated CFD model of PAR has been employed for developing an empirical correlation for Indian PAR. For this purpose, detailed parametric study involving different gas mixture variables at PAR inlet has been performed. For each case, respective values of gas mixture variables at recombiner outlet have been tabulated. The obtained data matrix has then been processed using regression analysis to obtain a set of correlations between inlet and outlet variables. The empirical correlation thus developed, can be easily plugged into commercially available CFD software.