• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.4
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• pp.568-574
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• 2020

Recently, the installation of energy storage systems (ESSs) that have a range of functions, such as power stabilization of renewable energy sources, demand control, and frequency regulation, has been increasing annually. On the other hand, since the fire accident of ESS occurred at Gochang Power Test Center in August 2017, 29 fire accidents with significant property losses have occurred, including the Gyeongsan substation and Kunsan PV power plant. Because these fire accidents of ESS are arisen regardless of the season and capacity of ESS, an analysis of the fault characteristics in ESS is required to confirm the causes of the fire accidents accurately and ensure the safety of the ESS. This paper proposes the modeling of ESS using PSCAD/EMTDC S/W to identify the fault characteristics and ensure the safety of the ESS. From the simulation results of fault characteristics based on various scenarios, it is clear that the insulation of ESS may be breakdown due to the largely occurring CMV (common mode voltage). Furthermore, the CMV between the PCS and battery can be reduced, and the insulation breakdown of ESS can be prevented if an SPD (surge protect device) is installed in the battery and PCS sides, respectively.

• Journal of Environmental Health Sciences
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• v.50 no.1
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• pp.25-35
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• 2024

Background: There are concerns about the health effects of various environmental pollution exposures among residents living near coal-fired power plants (CFPP). Objectives: This study attempted to compare the concentrations of heavy metals in blood and urine and those of urinary volatile organic compound (VOC) metabolites according to the residential separation distance. Methods: Participants in the study totaled 334 people who have lived for more than 10 years in areas within 10 km of a CFPP. The separation distance was analyzed in quartiles by dividing it into Q1 (88 people), Q2 (89 people), Q3 (89 people), and Q4 (68 people). We explained the purpose of this study to the participants and collected blood and urine after obtaining signatures on a participation agreement. Results: The study participants were 102 males (30.5%) and 232 females (69.5%), with an average age of 71. The average length of residence and distance were 43.8 years and 4,800 meters. The geometric mean concentrations of Pb, Cd, and Hg in blood and As and Cd in urine were respective 1.35 ㎍/dL, 1.43 ㎍/L, 3.16 ㎍/L. They were 167.88 ㎍/g for creatinine and 1.58 ㎍/g creatinine. The metabolite concentrations of VOCs were 50.67 ㎍/g creatinine in t, t-muconic acid (t, t-MA), 10.73 ㎍/g creatinine in benzyl mercapturic acid, 317.05 ㎍/g creatinine in phenylglyoxylic acid, 123.55 ㎍/g creatinine in methylhippuric acid, and 190.82 ㎍/g creatinine in mandelic acid. The concentration of Pb in the blood and Cd and t, t-MA in the urine of residents within affected area of the CFPP showed statistically significant differences among distance groups. Conclusions: The concentration of urinary VOCs metabolites, especially t, t-MA, differed according to the distance groups of residents within the affected area of CFPP (p<0.05).

• Journal of the Korean institute of surface engineering
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• v.42 no.6
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• pp.267-271
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• 2009

Multicomponent transparent conducting oxide films were deposited on glass substrates at 150 by dual magnetron sputtering of AZO and ITO targets. In the case of mixing a limited amount of ITO (10W), resistivity of TCO films was significantly increased compared to the AZO film; from $3.5{\times}10^{-3}$ to $9.7{\times}10^{-3}{\Omega}{\cdot}cm$. Deterioration of the electrical conductivity is attributed to the decreases in carrier concentration and Hall mobility. Improvement of the conductivity could be obtained for the films prepared with ITO powers larger than 40 W. The lowest resistivity ($\rho$) of $7.3{\times}10^{-4}{\Omega}{\cdot}cm$ was achieved when ITO power was 100 W. Effects of $H_2$ incorporation on the electrical and optical properties of AZO-ITO films were investigated in this work. Addition of small amount of hydrogen resulted in the increase of carrier concentration and the improvement of electrical conductivity. It is apparent that the roughness of AZO-ITO films decreases dramatically after the transition of microstructure from polycrystalline to amorphous phase, which gives practical advantages such as an excellent uniformity of surface and a high etching rate. AZO-ITO films grown at sputtering ambient with hydrogen gas are expected to be applicable to optoelectronic devices such as organic light emitting diodes and flexible displays due to their sufficient electrical and structural properties.

• Journal of the Society of Disaster Information
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• v.16 no.2
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• pp.223-236
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• 2020

Purpose: In this study, a strong wind damage prediction function was developed in order to be used as a contingency during disaster management (preventive-preventive-response-recovery). Method: The predicted strong wind damage function proposed in this study took into account the re-enactment boy power, weather data and local characteristics at the time of damage. The meteorological data utilized the wind speed, temperature, and damage history observed by the Korea Meteorological Administration, the disaster year, and the recovery costs, population, vinyl house area, and farm water contained in the disaster report as factors to reflect the regional characteristics. Result: The function developed in this study reflected the predicted weather factors and local characteristics based on the history of strong wind damage in the past, and the extent of damage can be predicted in a short time. Conclusion: Strong wind damage prediction functions developed in this study are believed to be available for effective disaster management, such as decision making by policy-makers, deployment of emergency personnel and disaster prevention resources.

• Journal of the Korean Institute of Landscape Architecture
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• v.28 no.2
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• pp.18-27
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• 2000

The importance of constraints has been one of major issues in recreation for prediction of choice behavior; however, traditional conjoint choice model did not consider the effects of these variables or fail to integrate them into choice model adequately. The purposes of this research are (a) to estimate the effects of constraints in theme park choice behavior by the constraints-induced conjoint choice model, and (b) to test additional explanatory power of the additional constraints in this suggested model against the more parsimonious traditional model. A leading polling agency was employed to select respondents. Both alternative generating and choice set generating fractional factorial design were conducted to meet the necessary and sufficient conditions for calibration of the constraints-induced conjoint choice model. Th alternative-specific model was calibrated. The log-likelihood ratio test revealed that suggested model was accepted in the favor of the traditional model, and the goodness-of-fit($\rho$$^2$) of suggested and traditional model was 0.48427 and 0.47950, respectively. There was no difference between traditional and suggested model in estimates of attribute levels of car and shuttle bus because alternatives were created to estimate the effects of constraints independently from mode related variables. Most parameters values of constraints had the expected sign and magnitude: the results reflected the characteristics of the theme parks, such as abundance of natural attractions and poor accessibility in Everland, location of major fun rides indoor in Lotte World, city park like characteristics of Dream Land, and traffic jams in Seoul. Instead of the multinomial logit model, the nested logit model is recommended for future researches because this model more reasonably reflects the real decision-making process in park choice. Development of new methodology too integrate this hierarchical decision-making into choice model is anticipated.

• The Journal of the Korea Contents Association
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• v.14 no.5
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• pp.8-17
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• 2014

Petascale systems(so called supercomputers) have been mainly used for supporting communication-intensive and tightly-coupled parallel computations based on message passing interfaces such as MPI(HPC: High-Performance Computing). On the other hand, computing paradigms such as High-Throughput Computing(HTC) mainly target compute-intensive (relatively low I/O requirements) applications consisting of many loosely-coupled tasks(there is no communication needed between them). In Korea, recently emerging applications from various scientific fields such as pharmaceutical domain, high-energy physics, and nuclear physics require a very large amount of computing power that cannot be supported by a single type of computing resources. In this paper, we present our HTCaaS(High-Throughput Computing as a Service) which can leverage national distributed computing resources in Korea to support these challenging HTC applications and describe the details of our system architecture, job execution scenario and case studies of various scientific applications.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.291-295
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• 2007

FTL(Fuel Test Loop) is a facility that confirms performance of nuclear fuel at a similar irradiation condition with that of nuclear power plant. FTL consists of In-Pile Test Section (IPS) and Out-Pile System (OPS). FTL construction work began on August, 2006 and ended on March, 2007. During Construction, ensuring the worker's safety was the top priority and installation of the FTL without hampering the integrity of the HANARO was the next one. Task Force Team was organized to do a construction systematically and the communication between members of the task force team was done through the CoP(community of Practice) notice board provided by the Institute. The installation works were done successfully overcoming the difficulties such as on the limited space, on the radiation hazard inside the reactor pool, and finally on the shortening of the shut down period of the HANARO. Without a sweet of the workers of the participating company of HEC(Hyundae Engineering Co, Ltd), HDEC(HyunDai Engineering & Construction Co. Ltd), equipment manufacturer, and the task force team, it is not possible to install the FTL facility within the planned shutdown period. The Commissioning of the FTL is on due to check the function and the performance of the equipment and the overall system as well. The FTL shall start operation with high burn up test fuels in early 2008 if the commissioning and licensing progress on schedule.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.6
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• pp.2698-2706
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• 2011

This paper deals with the optimal operation algorithm of SVR(Step Voltage Regulator) which is located with primary feeders and proposes the optimal operation system to evaluate customer voltage. The existing algorithm of SVR adapts the constant sending voltage method, which may cause the power quality problems such as overvoltage and under voltage variations in case where the distributed generations are interconnected with the primary feeders. Therefore, this paper proposes the optimal algorithm of LDC method for SVR using least square method to obtain the optimal setting values. Also, this paper presents the optimal evaluation system based on the former algorithm. The simulation results according to the types and capacities of distributed generations shows the effectiveness.

• 한국초전도학회:학술대회논문집
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• v.9
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• pp.210-213
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• 1999

Magnetoresistance and magnetization of Sr$_{l-x}K_xBiO_3$ were both measured as functions of temperature and magnetic field. Resistivity goes to zero at T=10.1K and the overall superconducting transition behavior under applied magnetic fields is similar to that of other BiO based superconductors. Also, below T<5K we have observed the reappearance of finite resistivity with a power law temperature dependence( ${\rho}$ ${\sim}$T$^1$); the reentrant superconducting transition of resistivity. Contrary to the Josephson weak link effect in polycrystalline samples, which gives the depression of the superconducting state with increasing electrical current or magnetic field, the superconducting state for T<5K is resumed by applying a higher current or magnetic field. Magnetic susceptibility( ${\chi}$ ) of Sr$_{l-x}K_xBiO_3$ for T<5K also shows similar trends to that observed in transport measurements: increase of ${\chi}$ (paramagnetic-like behavior) at a low magnetic fields(B=50 Oe) and, the resumption of perfect diamagnetism at high fields.

• Nuclear Engineering and Technology
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• v.52 no.3
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• pp.508-519
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• 2020

During transients or accidents, the reactor core is uncovered, and droplets entrained above the quench front collides with the uncovered fuel rod surface. Droplet impact cooling can reduce the peak cladding temperature. Besides zirconium-based cladding, versatile accidental tolerant fuel (ATF) claddings, including FeCrAl, have been proposed to increase the accident coping time. In order to investigate the effect of surface properties on droplet impact cooling of cladding surfaces, the droplet impact phenomena are photographed on the FeCrAl and zircaloy-4 (Zr-4) surfaces under different conditions. On the oxidized FeCrAl surface, the Leidenfrost phenomenon is not observed even when the surface temperature is as high as 550 ℃ with We > 30. Comparison of the impact behaviors observed on different materials shows that nucleate and transition boiling is more intensive on surfaces with larger thermal conductivity. The Leidenfrost point temperature (LPT) decreases with the solid thermal effusivity (${\sqrt{k{\rho}C_p}}$). However, the CHF temperature is relatively insensitive to the surface oxidation and Weber number. Droplet spreading diameter is analyzed quantitatively in the film boiling stage. Based on the energy balance a correlation is proposed for droplet maximum spreading factor. A mechanistic model is also developed for the LPT based on homogeneous nucleation theory.