• Journal of Korea Water Resources Association
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• v.37 no.10
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• pp.857-868
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• 2004

Since the self-purification capacity of rivers in Korea is significantly controlled by environmental maintenance flow supplied by upstream reservoirs during drought season, it is obviously important to operate the river and reservoir systems considering not only water quantity aspect but also conservation of downstream water quality and ecosystem. In this study, an unsteady river water quality model KORIVl- WIN was developed as a tool for evaluating the impact. of reservoir operations on the downstream water quality. The model parameters were calibrated and verified using field data obtained in Geum River on September and October of 2002, respectively. Intensive data sampling was performed on November 22, 2003 to investigate the effect of a short-term flushing discharge of Daecheong Reservoir, which increased outflow from 30 $m^3$/s to 200 $m^3$/s for 6 hours, on downstream water quality. The model performance was evaluated by comparing simulated results with observed data including hydraulics, biochemical oxygen demand(BOD$_{5}$), nitrogen and phosphorus species during the flushing event. It showed very good performance in predicting the travel time of flushing flow and water quality variations of dissolved forms of nitrogen and phosphorus species, while revealed large deviations for BOD$_{5}$ possibly due to missing the effect of organic matters resuspension from river bottom sediment during the wave front passage.

• Journal of Preventive Medicine and Public Health
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• v.22 no.3 s.27
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• pp.355-367
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• 1989

This study examined the physical and mental health factors affecting the industrial accidents of 142 injured and 1,212 uninjured workers in the shipbuilding industry from 1986 to 1988. The results acquired from the Todai Health Index (THI) and from analysis of the health examination were as follows: 1. Among the personal characteristics of the workers, the educational level of injured workers was significantly lower than that of the uninjured workers. 2. Among the physical characteristics, vision and $R\ddot{o}hrer$ Index of the injured workers were lower than those of the uninjured workers, and the difference was statistically significant. On the other hand, the differences in height, weight, hearing function, hematocrit, blood pressure, urine test, and X-ray findings were not statistically significant between the injured and uninjured workers. 3. The score of the THI questionnaire on the physical and mental health of the injured workers was higher than that of the uninjured workers, and the difference was statistically significant. 4. Form the THI score, the industrial workers had complained more about mental health than physical health and there was a statistically singinficant relation with the industrial accidents. 5. The relative risk expressed in terms of the odds ratio was 2.9 for poorer vision, 2.7 for a lower educational level, 2.2 for a higher THI score and 1.6 for overdrinking. 6 Educational level, vision, and the THI score were selected as significant factors influencing industrial accidents based on a log-linear model. According to the results of this model by logistic analysis, the odds ratio of industrial accidents was 1.8 for a lower educational level, 1.7 for poorer vision, and 1.6 for a higher THI score. 7 By event history analysis with the dependent variable as the duration of work at the time of the industrial accident, educational level, age, $R\ddot{o}hrer$ Index and THI score were the statistically significant variables selected, and the hazard rate of industrial accident occurrence was 0.24 for a lower educational level, 0.92 for age, 0.99 for a lower $R\ddot{o}hrer$ Index and 2.72 for a higher THI score. As we have seen, educational level and THI score were the most significant factors affecting the hazard rate of industrial accidents. Vision, $R\ddot{o}hrer$ Index, age, and drinking behavior were also statistically significant variables influencing industrial accidents. Therefore, in order to prevent industrial accidents, it is necessary to establish a health management plan for industry which can objectively evaluate not only the physical but also the mental health of the workers. If we use this type of study as a prospective study design, we can determine the relative risk of physical and mental health factors on industrial accidents. Furthermore, it is expected that this type of study will provide workers at high risk with more precise basic data for a health managment plan for industrial accident prevention.

• The Journal of Korean Medical History
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• v.26 no.1
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• pp.41-53
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• 2013

In this paper, King Kyung-Jong's strange diseases which had been exacerbated by the Sinim-Sahwa(辛壬士禍) are researched and discussed. The subject will be described mostly based on health and medical records from "The Daily Records of Royal Secretariat of Chosun Dynasty(承政院日記)" and "The Annals of the Choson Dynasty(朝鮮王朝實錄)". Sinim-Sahwa had occurred for two years. It is thought that the beginning of it was 'a controversy on a proclamation of a crown prince, Yeon Ing Goon'. At the first year of Kyung-Jong's ruling, August 21, the No-Ron demanded a king's heir be decided as soon as possible, the king asked Yeon Ing Goon as his successor because of his 'strange diseases'. In October of the same year, the conflict between No-Ron and So-Ron parties reached its peak after a dispute about 'regency from behind the veil for the crown prince' at that time. Kyung-jong added that he had a mysterious and heavy disease and there was little hope to recover from it. Some opposing courtiers emphasized the king was in his good health and there weren't any actual diseases he suffered. But Kyung-Jong stubbornly persisted the diseases he had were so heavy that he couldn't get well readily. In detail, he announced his disease had so deeply rooted in internal organs that he could feel some kind of heat and fire arousal form his heart, then rage and resent soaring. Eventually, on 16th, the No-Ron party followed the king's demand, thus the king's health and illness condition itself was gradually getting off the subject. It seems that Kyung-jong's strange diseases was hwa-byung(火病). His symtoms are similar to the symtoms of hwa-byung. Environment he lived, was enough to cause hwa-byung. as a result, Sinim-Sahwa was the event what his hwa(火) was erupted.

• Journal of the Korean Society for Nondestructive Testing
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• v.21 no.1
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• pp.80-90
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• 2001

The aim of this study is to develop the methodology which enables to identify the mechanical properties of element such as stress intensity factor by using the AE parameters. Considering the multivariate and nonlinear properties of AE parameters such as ringdown count, rise time, energy, event duration and peak amplitude from fatigue cracks of machine element the principal component regression(PCR) and artificial neural network(ANN) models for the estimation of stress intensity factor were developed and validated. The AE parameters were found to be very significant to estimate the stress intensity factor. Since the statistical values including correlation coefficients, standard mr of calibration, standard error of prediction and bias were stable, the PCR and ANN models for stress intensity factor were very robust. The performance of ANN model for unknown data of stress intensity factor was better than that of PCR model.

• Journal of Navigation and Port Research
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• v.32 no.6
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• pp.499-503
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• 2008

As the conference result of MEPC in IMO, development of ballast water management system corresponding to newly established ballast water management standard (D2 regulation) of shipping is being made an active progress over the whole world. The ballast water management system should treat particular material of more than $10{\mu}m$ in high capacity of more than 500t per hour in the event of filtration process. Also, it is very difficult to develop a practical management system since a limited element which a narrow space of the ship should be designed in the minimal volume is assumed. Therefore, the study promoted a study on the next generation auto back wash media filter to overcome such a limited element. Also, the study performed pressure and flux measurement test followed by thickness of each filter medium for filtration by each size to grasp a relation between absorption and pressure at the time of vacuum filtration and mechanical analysis and turbidity change observation of filtered water after vacuum filtration.

• Journal of the Korean Regional Science Association
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• v.37 no.4
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• pp.33-47
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• 2021

In urban declining areas, the population is decreasing, and drying environments such as buildings and facilities are aging. Therefore, it is vulnerable in the event of disaster, and recovery takes a lot of time and money. The purpose of this study is to develop an evaluation technique for comprehensively diagnosing disasters in declining areas and to present implications through case analysis. Evaluation indicators were selected to calculate the comprehensive diagnosis index of disasters, and weights were calculated for each class, including disaster types, components, and evaluation indicators, through Analytic Hierarchy Process analysis. The comprehensive diagnoses index for each type of disaster was calculated with the calculated weight, and the risk according to the level of urban decline was analyzed. As a result of analyzing Seoul as a case area, it was analyzed that the overall risk of disasters was high in southern regions such as Seocho-gu, Dongjak-gu, Geumcheon-gu, and Gangseo-gu, and relatively low in downtown and northern Seoul, parks and green areas. The results of this study are of academic significance in that they presented a comprehensive diagnostic index evaluation system and technique for each type of disaster, including natural and social disasters.

• Journal of the Korean Institute of Gas
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• v.23 no.4
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• pp.1-9
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• 2019

Large-scale industrial boilers operating at high temperature and high pressure, have a large amount of water, and a large amount of energy is released at the time of explosion. Currently, most industrial boilers use gas fuel such as LNG and LPG, etc. and fuel exists in the same space as equipment, so there is a high possibility of secondary damage such as fire or explosion in the event of a boiler accident. Both special care and management are required to operate the very dangerous equipment that causes casualty 2.51 per accident. For boilers of a certain size or more, the Korea Energy Agency conducts inspections in accordance with the Energy Usage Rationalization Act, KS, and public notice of the Ministry of Industry, Trade and Resources. In this research, based on the results of the inspection, the hazard factorss are configured, and a questionnaire is conducted to the inspector, the equipment manager, the maintenance person, and the person in charge of the manufacturer. We analyzed the results by using AHP (Analytic Hierarchy Process). As a result of analysis, generally recognized hazard factorss are not good management, measurement failure, specification failure, water leak, leak analysis, but connection, welding, scale, and corrosion, etc. are relatively less important. It is judged that the adverse factors that are recognized to be highly important among all groups and careers are already well managed, but less important and adverse factors should be well managed to ensure that the safe usage of the boiler.

• Land and Housing Review
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• v.13 no.4
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• pp.1-12
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• 2022

Clean water is an essential urban infrastructure in human daily life, and water plays a vital role in public health. Due to restrictions on outdoor activities during COVID-19, time staying at home has increased. Therefore, it is plausible to assume that large-scale disaster incidences such as COVID-19 will affect water consumption. In this regard, this research aims to explore the factors that influence household water use during COVID-19. The analysis period of the study is 2020, and the geographical scope covers Seoul and Incheon. A dependent variable was water consumption in the autonomous districts of Seoul and Incheon, and the factors reflecting urban characteristics were used as independent variables. Multiple regression was used for analysis, and the unit of analysis was the autonomous district in Seoul and Incheon. The finding confirmed that the pandemic situation caused an increase in water consumption. In addition, it supports policy for the elderly so that they can use water without financial difficulty. It implies that a stable supply of clean water is essential for managing infectious diseases. The findings of this study are expected to provide some implications for efficient water supply policies and efficient water supply management in the event of the spread of infectious diseases such as COVID-19.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.6
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• pp.1069-1074
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• 2020

Since DC has no zero point, an arc occurs when the DC circuit breaker performs a shutdown operation. In this case, a fatal accident may occur in the circuit breaker or in the grid, depending on the magnitude of the arc. Therefore, the shutdown performance and the reliability of the circuit breaker are important in the commercialization of HVDC. In this study, a superconducting LC circuit breaker was proposed to improve the performance and the reliability of the DC circuit breaker. The superconducting LC circuit breaker applied a superconducting coil to the inductor of the existing LC circuit breaker. Other than limiting the initial fault current, it also creates a stable zero point in the event of a fault current. To verify this, simulation was performed through EMTDC/PSCAD. Furthermore, the superconducting LC circuit breaker was compared with the LC circuit breaker with a normal coil. As a result, it was found that the LC circuit breaker with the superconducting coil limited the initial fault current further by approximately 12 kA compared to the LC circuit breaker with a normal coil. This reduced the arc extinguish time by approximately 0.16 sec, thereby decreasing the elctrical power burden on the circuit breaker.

• Korean Journal of Remote Sensing
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• v.38 no.6_1
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• pp.1069-1080
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• 2022

The tropospheric ozone is a pollutant that causes a great deal of damage to humans and ecosystems worldwide. In the event that ozone moves downwind from its source, a localized problem becomes a regional and global problem. To enhance ozone monitoring efficiency, geostationary satellites with continuous diurnal observations have been developed. The objective of this study is to derive the Tropospheric Ozone Movement Vector (TOMV) by employing continuous observations of tropospheric ozone from geostationary satellites for the first time in the world. In the absence of Geostationary Environmental Monitoring Satellite (GEMS) tropospheric ozone observation data, the GEOS-Chem model calculated values were used as synthetic data. Comparing TOMV with GEOS-Chem, the TOMV algorithm overestimated wind speed, but it correctly calculated wind direction represented by pollution movement. The ozone influx can also be calculated using the calculated ozone movement speed and direction multiplied by the observed ozone concentration. As an alternative to a backward trajectory method, this approach will provide better forecasting and analysis by monitoring tropospheric ozone inflow characteristics on a continuous basis. However, if the boundary of the ozone distribution is unclear, motion detection may not be accurate. In spite of this, the TOMV method may prove useful for monitoring and forecasting pollution based on geostationary environmental satellites in the future.