• Korean Journal of Construction Engineering and Management
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• v.24 no.6
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• pp.74-80
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• 2023

This study examines the characteristics of architectural review opinions as unstructured data, focusing on the most challenging risk for developers of small and medium-sized apartment projects in response to the increasing number of single-person households in Korea. Using multidimensional analysis methods, the study analyzes the review opinions of 25 projects in B City. Correspondence analysis and MDS (Multidimensional Scale) analysis show that, consistent with prior research, the keywords related to 'structure' and 'planning' dominate architectural review opinions in B City. While the MDS model's stress is very poor at 34.4%, correspondence analysis reveals that this is due to the characteristics of unstructured data in architectural reviews. In addition, the non-structured data analyzed in this study, such as architectural review opinions, exhibited a probability distribution with low kurtosis and high skewness, as they involved various combinations and occurrences of data depending on the discretion of the review committee members and the specific formats of different local governments. This often led to the emergence of keywords that differed significantly from commonly mentioned terms. Although the study has some limitations, it provides a foundation for future detailed analysis by identifying the characteristics of architectural review opinions as unstructured data.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.6 no.4
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• pp.245-255
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• 2008

Korea Hydro and Nuclear Power Company(KHNP) conducted site investigations for a low and intermediate-level nuclear waste repository in the Gyeong Ju site. The site characterization work constitutes a description of the site, its regional setting and the current state of the geosphere and biosphere. The main objectives of hydogeological investigation aimed to understand the hydrogeological setting and conditions of the site, and to provide the input parameters for safety evaluation. The hydogeological characterization of the site was performed from the results of surface based investigations, i.e geological mapping and analysis, drilling works and hydraulic testing, and geophysical survey and interpretation. The hydro-structural model based on the hydrogeological characterization consists of one-Hydraulic Soil Domain, three-Hydraulic Rock Domains and five-Hydraulic Conductor Domains. The hydrogeological framework and the hydraulic values provided for each hydraulic unit over a relevant scale were used as the baseline for the conceptualization and interpretation of flow modeling. The current hydrogeological characteristics based on the surface based investigation include some uncertainties resulted from the basic assumption of investigation methods and field data. Therefore, the reassessment of hydrostructure model and hydraulic properties based on the field data obtained during the construction is necessitated for a final hydrogeological characterization.

• Journal of Energy Engineering
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• v.27 no.4
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• pp.27-35
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• 2018

The passive containment cooling system (PCCS) has been designed to remove the released decay heat during the accident by means of the condensation heat transfer phenomenon to guarantee the safety of the nuclear power plant. The heat removal performance of the PCCS is mainly governed by the condensation heat transfer of the steam-air mixture. In this study, the heat removal performance of the PCCS was evaluated by using the MARS-KS code with a new empirical correlation for steam condensation in the presence of a noncondensable gas. A new empirical correlation implemented into the MARS-KS code was developed as a function of parameters that affect the condensation heat transfer coefficient, such as the pressure, the wall subcooling, the noncondensable gas mass fraction and the aspect ratio of the condenser tube. The empirical correlation was applied to the MARS-KS code to replace the default Colburn-Hougen model. The various thermal-hydraulic parameters during the operation of the PCCS follonwing a large-break loss-of-coolant-accident were analyzed. The transient pressure behavior inside the containment from the MARS-KS with the empirical correlation was compared with calculated with the Colburn-Hougen model.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.151.2-151.2
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• 2010

우리나라는 "제 3차 신재생에너지 기술개발 및 이용 보급 기본계획"을 통해 2030년까지 111.5조 원을 투자하여 전체 에너지의 11%를 신재생에너지로 공급한다는 목표를 설정하였다. 그러나 신재생에너지는 기존의 원자력이나 화석에너지에 비하여 생산비용이 높아 보조나 융자 등의 정부지원에 의존하여 보급이 이루어져왔다. 신재생에너지 보급확대 및 산업발전을 위한 보급정책의 일환으로 정부는 2012년부터 RPS(Renewable Portfolio Standard, 신재생에너지 공급의 무화제도)를 도입키로 확정하였다. RPS의 도입은 일정규모 신재생에너지 시장수요를 창출함과 동시에 신재생에너지원간 가격경쟁 구도 형성의 유인이 될 수 있다. 이는 전력가격 일괄상승 및 녹색가격제도(Green Pricing) 등의 정책적 논의로 이어질 수 있다. 따라서 소비자 측면에서 신재생에너지 전력의 가치를 어떻게 평가하는지를 분석하여 RPS 시행제반의 정책적 논의의 기초자료를 마련할 필요가 있다. 특히 RPS는 신재생에너지원 간의 경쟁을 가능하게 하므로 개별 신재생에너지원에 따라 소비자 선호의 차이가 어떻게 나타나는지 연구되어야 한다. 이에 본 연구는 환경재 혹은 비시장재화의 가치추정에 가장 널리 활용되고 있는 조건부가치평가법(Contingent Valuation Method; CVM)을 적용하여 풍력, 태양광, 수력으로 생산한 전력에 대한 소비자의 지불의사액(Willingness to Pay; WTP)을 분석하는 모형을 수립하였다. 이를 위해 Zografakis et al.(2010), Yoo and Kwak(2009), 이창훈 황석준(2009), Nomura and Akai(2004), Bately et al.(2001) 등의 선행연구를 참조하여 신재생에너지 전력 가치의 설문에서 고려되어야 하는 요인들을 선정하였다. 이를 토대로 설문 시나리오를 작성하여 각 요인들이 신재생에너지 전력에 대한 지불의사액 결정에 어떠한 영향을 미치는지 분석가능한 모형을 설정하였다. 뿐만 아니라 기존 연구들이 신재생에너지로 생산된 일반적인 전력에 대한 지불의사액을 질문하는데 그쳤다면, 본 연구에서는 각 원별로 지불의사액의 차이를 도출할 수 있는 설문모형을 구축하는데 중점을 두었다. 본 연구결과는 향후 설문수행을 통하여 신재생에너지원별로 소비자의 선호를 분석할 수 있는 연구로 발전될 수 있으며, 이는 RPS 도입으로 인한 전력가격 정책 수립의 기초 연구자료로 활용될 수 있다 하겠다.

• Journal of Energy Engineering
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• v.26 no.3
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• pp.64-70
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• 2017

The concept of Hybrid Safety Injection Tank (Hybrid SIT) proposed by the Korea Atomic Energy Research Institute (KAERI) has been introduced for the purpose of application to the Advanced Power Reactor Plus (APR+). In this study, the SBO situation of the APR+ was analyzed by using the MARS-KS code in order to evaluate whether the operation of the Hybrid SIT has an effect on the cooling performance of the Reactor Coolant System (RCS). According to the analysis, when the actuation valve on the pressure balancing line (PBL) is opened, the Hybrid SIT's pressure rises rapidly, forming equilibrium with the RCS pressure; subsequently, a flow is injected from the Hybrid SIT into the reactor vessel through the direct vessel injection (DVI) line. The analysis showed that it is possible to keep the core temperature below melting temperature during the operation of a Hybrid SIT.

• Nuclear Engineering and Technology
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• v.26 no.1
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• pp.126-139
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• 1994

Best-estimate thermal-hydraulic codes, CATHARE2 V1.2 and RELAP5/MOD3, hate been assessed against the BETHSY 6.2 tc six-inch cold leg break loss-of-coolant accident (LOCA) test. Main objective is to analyze the overall capabilities of the two codes on physical phenomena of concern during the small break LOCA i.e. two-phase critical flow, depressurization, core water level de-pression, loop seal clearing, liquid holdup, etc. The calculation results show that the too codes predict well both in the occurrences and trends of major two-phase flow phenomena observed. Especially, the CATHARE2 calculations show better agreements with the experimental data. However, the two codes, in common, show some deviations in the predictions of loop seal clearing, collapsed core water level after the loop seal clearing, and accumulator injection behaviors. The discrepancies found from the comprision with the experimental data are larger in the RELAP5 results than in the CATHARE2. To analyze the deviations of the two code predictions in detail, several sensitivity calculations have been performed. In addition to the change of two-phase discharge coefficients for the break junction, fine nodalization and some corrections of the interphase drag term are made. For CATHARE2, the change of interphase drag force improves the mass distribution in the primary side. And the prediction of SG pressure is improved by the modification of boundary conditions. For RELAP5, any single input change doesn't improve the whole result and it is found that the interphase drag model has still large uncertainties.

• Environmental and Resource Economics Review
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• v.18 no.2
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• pp.217-239
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• 2009

As gas hydrate is recently emerging as a new energy source to solve environmental and exhaustion problems caused by fossil energy, Korea is working on a gas hydrate development project under a 10-year plan from 2005 to 2014. Gas hydrate is expected to have a big effect on the economy and society of Korea, which is largely depending on energy imports besides water energy and atomic energy. However, it is uncertain whether the project will produce successful results. Thus, it is very important to improve its validity and to propose effective execution strategies by evaluating the value of the project in advance. Thus, this study intended to include new information, which had not been evaluated in existing methods, and to reduce biases or errors in value evaluation results by applying a fuzzy risk analysis to the real option model in order to evaluate the value of a gas hydrate development project. It is advantageous that the real option model based on the fuzzy risk analysis modelizes the vagueness and inexactness of intangible element judgment into an appropriate language scale so as to evaluate these elements clearly and integrate them with estimated financial performance results. The application of the fuzzy risk analysis makes it possible to conduct an analysis by dissolving a decision-making issue with complicated and various attributes into several simplified problems. With the continuing high oil prices and today's demand of clean energy, the necessity of energy resources and technology development projects keeps growing. Amid this situation, it is expected that these study results will contribute to proposing a guideline not only for gas hydrate projects but also for policy decision-making related to future energy industries.

• Nuclear Engineering and Technology
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• v.22 no.1
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• pp.20-28
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• 1990

In this study the migration experiment using packed column with crushed tuff was conducted as a basic research to develop migration model of radionuclides through geologic media. The main emphasis was put on evaluating the validity of migration models. For this, two models were introduced: one is the model which is based on the assumption of instantaneous equilibrium reaction and the other the model based on kinetic process such as intraparticle diffusion. The coefficient of hydrodynamic dispersion in packed column was determined using iodine as nonsorbing tracer. The hydrodynamic dispersion coefficient, D$_{L}$ was shown to be 0.11$\times$10$^{-2}$ $\textrm{cm}^2$/min under the condition of the column porosity of 0.483 and the average water velocity of 0.915$\times$10$^{-2}$ cm/min. The distribution coefficient, Kd of Cs-137 on crushed tuff was 11.3 cc/g at the concentration of 2$\times$10$^{-6}$ M and the temperature of 2$0^{\circ}C$. The breakthrough curve of Cs-137 through packed column was shown to have an asymmetric curve in which long trailing tail appears at the end part of the curve. The results obtained from the comparison of introduced models with experimental data indicated that the mass transfer model with intraparticle diffusion as rate-controlling step simulated the behaviors of Cs-137 migration more adequately, when compared with the bulk reaction model in which the assumption of instantaneous equilibrium reaction was maded. Consequently, the intraparticle diffusion was found to be an important factor in the migration of Cs-137 through packed column.n.

• Journal of Digital Convergence
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• v.17 no.7
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• pp.131-138
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• 2019

The world's electricity production ratio is 40% for coal, 20% for natural gas, 16% for hydroelectric power, 15% for nuclear power and 6% for petroleum. Fossil fuels also cause serious problems in terms of price and supply because of the high concentration of resources on the earth. Solar energy is attracting attention as a next-generation eco-friendly energy that will replace fossil fuels with these problems. In this study, we test the charge-operation plan and the discharge operation plan for peak-cut operation by applying the maximum power demand reduction simulation. To do this, we selected the electricity usage from November to February, which has the largest amount of power usage, and applied charge / discharge logic. Simulation results show that the contract power decreases as the peak demand power after the ESS Peak-cut service is reduced to 50% of the peak-target power. As a result, the contract power reduction can reduce the basic power value of the customer and not only the economic superiority can be expected, but also contribute to the improvement of the electric quality and stabilization of the power supply system.

• Journal of Korea Water Resources Association
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• v.53 no.12
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• pp.1159-1172
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• 2020

This study applied deep convolution neural network based on U-Net and SegNet using long period weather radar data to very short-term rainfall prediction. And the results were compared and evaluated with the translation model. For training and validation of deep neural network, Mt. Gwanak and Mt. Gwangdeoksan radar data were collected from 2010 to 2016 and converted to a gray-scale image file in an HDF5 format with a 1km spatial resolution. The deep neural network model was trained to predict precipitation after 10 minutes by using the four consecutive radar image data, and the recursive method of repeating forecasts was applied to carry out lead time 60 minutes with the pretrained deep neural network model. To evaluate the performance of deep neural network prediction model, 24 rain cases in 2017 were forecast for rainfall up to 60 minutes in advance. As a result of evaluating the predicted performance by calculating the mean absolute error (MAE) and critical success index (CSI) at the threshold of 0.1, 1, and 5 mm/hr, the deep neural network model showed better performance in the case of rainfall threshold of 0.1, 1 mm/hr in terms of MAE, and showed better performance than the translation model for lead time 50 minutes in terms of CSI. In particular, although the deep neural network prediction model performed generally better than the translation model for weak rainfall of 5 mm/hr or less, the deep neural network prediction model had limitations in predicting distinct precipitation characteristics of high intensity as a result of the evaluation of threshold of 5 mm/hr. The longer lead time, the spatial smoothness increase with lead time thereby reducing the accuracy of rainfall prediction The translation model turned out to be superior in predicting the exceedance of higher intensity thresholds (> 5 mm/hr) because it preserves distinct precipitation characteristics, but the rainfall position tends to shift incorrectly. This study are expected to be helpful for the improvement of radar rainfall prediction model using deep neural networks in the future. In addition, the massive weather radar data established in this study will be provided through open repositories for future use in subsequent studies.