• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.10
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• pp.1278-1285
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• 2018

For saving electricity bill, energy storage system(ESS) is being installed in factories, public building and commercial building with a Time-of-Use(TOU) tariff which consists of demand charge(KRW/kW) and energy charge(KRW/kWh). However, both of peak reduction and ESS special tariff are not considered in an analysis of initial cost payback period(ICPP) on ESS. Since it is difficult to reflect base rate by an amount of uncertain peak demand reduction during mid-peak and on-peak periods in the future days. Therefore, the ICPP on ESS can be increased. Based on this background, this paper presents the advanced analysis method for the ICPP on ESS. In the proposed algorithm, the representative days of monthly electricity consumption pattern for the amount of peak reduction can be found by the k­means clustering algorithm. Moreover, the total expected energy costs of representative days are minimized by optimal daily ESS operation considering both peak reduction and the special tariff through a mixed-integer linear programming(MILP). And then, the amount of peak reduction becomes a value that the sum of the expected energy costs for 12 months is maximum. The annual benefit cost is decided by the amount of annual peak reduction. Two simulation cases are considered in this study, which one only considers the special tariff and another considers both of the special tariff and amount of peak reduction. The ICPP in the proposed method is shortened by 18 months compared to the conventional method.

• Journal of Biosystems Engineering
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• v.8 no.2
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• pp.39-48
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• 1983

This study was performed to obtain the basic data which could be used for the modification of the manual center-burner-type rice-husk furnace into a small scale automatic type for the multi-purpose use in the farm. For this purpose, first, the utilization feasibility of the rice-husk furnace in the farm was analyzed briefly in aspects of available amount of rice-husk for the fuel, annual operation time and replaceble amount of residential heating energy with rice-husk in the farm. For the experiment a prototype furnace geared with an automatic feeding device was fabricated, and feed rate, mold size and chimney height were changed to investigate the combustion efficiency of rice-husk and thermal efficiency of the furnace. Also, optimum and limiting operational factors were observed in each treatments. The results obtained are summarized as follows. 1. If the rice-husk is intensively used for residential heating in the farm for winter season, on an average 51 percent of the total heating energy can be replaced with the rice-husk. Therefore, development of a small scale automatic rice-husk furnace was recognized to be feasible. 2. The operational condition depending on husk-feed rates was very important factor for successive steady burning operation of the given furnace. When the feed-rate was 1.5 kg/hr, the top of the burning zone should be kept at the position about 55 cm from the bottom of the combustion chamber with the periodic removal of ash (termed as steady state position), which was 18 cm above the mold waist. When the feed rates were 2.4 kg/hr and 3.0 kg/hr, the steady state position was at about 4 cm above the mold waist. 3. The mold size affected inflow rate of air into the furnace and consequently CO content in the exhaust gas. The relatively bigger mold gave positive effect on the air-inflow rate. 4. When the husk-feed rates were 1.5 kg/hr, 2.4 kg/hr, 3.0 kg/hr, the combustion efficiencies of the rice-husk were 98.5%, 97.4% and 95.0%, the thermal efficiencies of the furnace were 93.4%, 93.2% and 87.6%, and CO content in the exhaust gas were 1.21%, 1.03%, and 2.43%, respectively. The air-inflow rates were decreased with the increase of feed rates. When the amount of excess air was 30-40%, the CO content in the exhaust gas was at the minimum level. 5. When the chimney height was lowered from 260 cm to 96 cm, the air-inflow rate was slightly decreased, but the average temperature in the combustion chamber, CO content in the exhaust gas and combustion and thermal efficiencies were not changed significantly. 6. The incidental problems associated with the protytype furnace were accumulation of the ash inside the mold, accumulation of the cinder between the outer-drum of the furnace and the combustion chamber wall, and accumulation of the cinder in the chimney.

• Journal of Korea Water Resources Association
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• v.41 no.7
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• pp.711-723
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• 2008

In this study, Hydrologic regime alterations(magnitude, magnitude and duration of annual extreme, frequency and duration of high and low pulse, rate and frequency of water condition changes, Range of Variability Approach) were analyzed by using Indicators of Hydrologic Alterations at the 11 major multi-purpose dam. The analysis result of the magnitude of monthly water conditions during drought season, inflow was $6.38m^3/sec{\sim}39.84m^3/sec$ and outflow was $20.36m^3/sec{\sim}49.43m^3/sec$, was increased $1.84%{\sim}200.98%$. The analysis result of the magnitude of monthly water conditions during flood season, inflow was from $79.06m^3/sec{\sim}137.12m^3/sec$ and outflow was from $65.32m^3/sec{\sim}80.16m^3/sec$, was decreased from $18.19%{\sim}40.39%$. The analysis result of the magnitude and duration of annual extreme, 1-day minimum was increased $82.86%{\sim}2,950%$, but 1-day maximum was decreased $34.78%{\sim}83.96%$. The analysis result of the frequency and duration of high and low pulse, low pulse count was decreased $29.67%{\sim}99.07%$ and high pulse count was also decreased $4.6%{\sim}92.35%$ after dam operation. Hydrograph rise rate was decreased $15.84%{\sim}79.31%$ and fall rate was $1.97%{\sim}107.10%$. RVA of 1-day minimum was increased $0.60{\sim}2.67$, also RVA of 1-day maximum was decreased $0.50{\sim}1.00$.

• Journal of the Korean Society of Safety
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• v.32 no.3
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• pp.151-159
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• 2017

This study deals with characteristics and risk of a PM based on user survey result, road driving test and data analysis of PM accident. Text mining method is applied to extract PM accident data from Big Data, which are claim data of private insurance company. Road driving test and survey on safety, convenience, noise, overtake ability, steering ability, and climbing ability of PM are performed to evaluate user's safety and convenience considering domestic road condition. As the result of claim data analysis, annual average increase rate of PM accident is 47.4% and average compensation of personal mobility is higher than that of bicycle by maximum 1.5 times. 79.8% of PM accident is self-caused accident due to unskilled driving and age-specific diagnosis rate of driver over 60 is higher than that of under 60. Diagnosis rate of over 60 at lower limb, foot, rib and spine is especially higher than that of under 60. As the result of road driving test and user survey, satisfaction level on safety and convenience of PM is evaluated as close to that of bicycle and satisfaction level of PM is increased after boarding. Overtake ability, steering ability, and climbing ability of PM are evaluated as same or better than that of bicycle but warning equipment to pedestrian or bike such as horn is required because noise level of PM during driving is too low. Finally, user survey result shows that bicycle road is suitable for PM and safety standard, advance-education and insurance are required for PM. It is suggested that drivers' license for PM can be replaced by advance-education. Results of this study can be used to prepare safety measures and legal basis for PM operation.

• Journal of Korean Society of Rural Planning
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• v.26 no.2
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• pp.61-70
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• 2020

The purpose of this study is to calculate the annual carbon reduction of crops according to the carbon fixation method of agricultural land, therefore to analyze whether the economic inducement of farmers to switch from single cropping to double cropping if the amount of carbon reduction were traded on the Korea Exchange. The analysis targets were Gyeonggi Province, which was divided into four areas to compare the difference between agricultural income and carbon income by crop and cropping system. Agricultural profit was estimated by multiplying the prior data of 2012 by the change rate of the consumer price index, and carbon income was calculated through the carbon reduction for each crop and the average transaction price of KAU19 traded on the Korea Exchange. According to the analysis, the profit rate of double cropping in all areas is -110.4% to 23% compared to single cropping, when only agricultural profit is taken into account, with no economic inducement for farmers to change the cropping system. However, when carbon income is taken into account together, the profit rate of double cropping rises significantly from 122.5% to 238.9% over a single operation in all areas, resulting in an economic inducement to switch the cropping system. This research is meaningful in that farming households could raise their income by additional carbon income, and that carbon credits could be supplied at Korea Exchange to further boost the carbon emission exchange.

• Journal of Chest Surgery
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• v.35 no.11
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• pp.799-806
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• 2002

In spite of the establishment of chemotherapy and the gradual decrease in prevalence, pulmonary tuberculosis is still mainly treated with an operation. Through analyzing and examining some cases of surgical treatment, we hope to provide some help in treating of pulmonary tuberculosis in the future. Material and Method: By comparing four journals previously published in our department with 144 cases of lung surgery during ten years from January of 1991 to December of 2000 performed by the department of thoracic and cardiovascular surgery of the National Medical Center, we analyzed and reviewed the most recent trends and the results of the surgical treatment. Annual frequency of the operation, distribution of age, examination of sputum, adaptability and types of techniques, complications, and results of the postoperative follow-up were used as methods. Result: It was found that the annual frequency of operations had decreased. The ratio of men to women, 2:1 indicates that there are more incidences in men. Aging of patients could be speculated by the .results that the decrease in the incidence rate in the 20s age range and increase rate in the 50s age range. The range of preoperative lesions belonged mostly to far advanced and moderately advanced tuberculosis. By monitoring the period of use in preoperative antituberculosis drugs, cases for more than 3 years remarkably increased from 16.0 % to 55.6 %. The positive reactive rate for preoperative sputum examinations were drastically decreased from 91 % to 27 %. Total pulmonary destruction and partial destruction were the most common cases in terms of adaptability to the operations and there were significant increases in forming empyema accompanied by parenchymal lesions from 4.0 % to 20.1 %. Pneumonectomy and pulmonary lobectomy were the major type of operations. Especially, there were increases in the incident rate of empyema and recurrence of tuberculosis resulted. Post operative follow-up indicates that the rate of complete recovery was more than 70 % and the rate of gradual increase in treating with persistent antituberculosis drug was from 5.8 % to 18.0 %. Conclusion: In recent cases, there is an increasing number of patients showing tolerance to chemotherapy. Patients with pleural tuberculosis and severe lesions were typically increased. It is important to accurately analyze those complaints accurately that are mostly difficult to be treated medically. Surgical treatment is strongly recommended Before multiple drug resistance occurs.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.56 no.3
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• pp.258-264
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• 2020

This study aimed to analyze the economic feasibility of the reduction of working safety accidents in stow net fishery through the prevention education to fishing crews. The benefit was evaluated by estimating insurance payment amount that was reduced through prevention education. The decreasing rate of working safety accidents was presumed to follow the experience in Japan. The cost was assumed as the cost of textbook development. Results indicated that IRR was estimated to be 79.9% in case of scenario assuming no additional operating costs while IRR was 56.3% in case of scenario assuming 10% additional operating costs. In addition, the economic feasibility would be secured when annual operating costs increased to 274 million won according to the result of sensitivity analysis.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.13 no.3
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• pp.368-375
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• 2006

Purpose: The purpose of this study was to investigate the risk factors of exposure to blood and body fluid by clinical nurses. Method: The participants in this descriptive study were 276 clinical nurses involved in nursing care in a general hospital located in Seoul. The collected data were analyzed using a logistic regression model. Results: The annual exposure rate to blood and body fluid by clinical nurses was 66.3%, and the ratio was higher in the exposed group than in the non-exposed group for nurses under the age of 25, nurses who were unmarried, nurses with low clinical experience, and nurses who work night shifts more than six days a week. Clinical nurses who were unmarried were 1.9 times more likely to have been exposed compared to married nurses. Nurses whose work experience was less than 18 months were 2.7 times more at risk than nurses with more than 18 months of experience. Also, nurses whose fatigue scores were high had an increased chance of exposure (1.9 times). Conclusion: It is necessary to provide intensive training programs for clinical nurses who are in the early months of their career and are likely to be young and unmarried, in order to prevent exposure to blood and body fluid. Administrative supports to self-control and hospital ward operation measures to relieve nurses' fatigue should be provided.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.3
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• pp.54-60
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• 2015

There are 5 purification plants with the adopted advanced water purification treatment process in Korea. Annual operating costs were 8,990 million won including purchase cost of oxygen and power usage charges. We need research to optimize, in the future, when considering the direction of domestic water treatment continues to adopt advanced water treatment process. In this paper, calculate the optimal operating costs by injected the oxygen gas, used power cost. approximately 25% of the operating costs can be reduced when injected the ozone gas is 1.0ppm than 2.0ppm, the necessary amount of oxygen is increased then power is lower. so operating costs are decided according to oxygen costs. On the other hand, high ozone concentration 2.0ppm, the necessary power is increased then amount of oxygen is lower. Therefore, in the case of G purification plant, the controlling factor of the input ozone concentration 2ppm, PID control operation by setting the concentration of over 10Wt% is efficient. The installed capacity is the more little the more better when considering on Ozone injection rate in the process of water treatment.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.5
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• pp.1159-1166
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• 1994

This study presents the methodology for the performance analysis and prediction of small hydro power plants(SHP). Rainfall data are characterized to estimate the flow duration curve of SHP, using the cumulative density function of Weibull distribution. The model for the performance analysis of SHP is developed. Also, the performance characteristics of the existing Anheung Plant located in Han River basin are analyzed by using the developed model. As a result, it was found that the model is suitable to analyze the performance characteristics of existing SHP and to predict the primary design performance such as the design flowrate, capacity, rate of operation and annual electricity production of SHP.