• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.3
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• pp.513-521
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• 2017

Robust optimal operation of a microgrid is required since the increase of the penetration level of renewable generators in the microgrid raises uncertainty due to their intermittent power output. In this paper, an application of probabilistic optimization method to economical operation of a microgrid is studied. To simplify the treatment of the uncertainties of renewable generations and load, the new 'band of virtual equivalent load variation' is introduced considering their uncertainties. A simplified robust optimization methodology to generate the scenarios within the band of virtual equivalent load variation and to obtain the optimal solution for the worst scenario is presented based on Monte Carlo method. The microgrid to be studied here is composed of distributed generation system(DGs), battery systems and loads. The distributed generation systems include combined heat and power(CHP) and small generators such as diesel generators and the renewable energy generators such as photovoltaic(PV) systems and wind power systems. The modeling of the objective function for considering interruption cost by the penalty function is presented. Through the case study for a microgrid with uncertainties, the validity of proposed robust optimization methodology is evaluated.

• Archives of Pharmacal Research
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• v.22 no.2
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• pp.213-218
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• 1999

The antioxidant activity of Eriobotrya japonica was determined by measuring the radical scavenging effect on DPPH (1,1-diphenyl-2-picrylhydrazyl) radical and lipid peroxidation produced when mouse liver homogenate was exposed to the air at $37^{\circ}C$, using 2-thiobarbituric acid (TBA). The methanol extract and its factions of Eriobotrya japonica leaves showed strong antioxidant activity. The antioxidant activity of EtOAc and n-BuOH soluble fractions were stronger than the others, and were further purified by repeated silica gel, MCl gel CHP-20P, and Sephadex LH-20 column chromatography. Antioxidant chlorogenic acid, quercetin-3-sambubioside from n-BuOH fraction and methyl chlorogenate, kaempferol- and quercetin-3-rhamnosides, together with the inactive ursolic acid and$ 2{\alpha}$-hydroxyursolic acid from EtOAc fraction were isolated. Antioxidant flavonoids and chlorogenic acid also showed prominent inhibitory activity against free radical generation in dichlorofluorescein (DCF) method.

• Journal of the Korea Society of Computer and Information
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• v.24 no.3
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• pp.29-39
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• 2019

In this study, we introduce a model that satisfies energy efficiency and economical efficiency by introducing and demonstrating cogeneration generators in industrial complexes using various actual data collected at the site. The proposed model is composed of three scenarios, ie, full - time operation, scenario operated according to demand, and a fusion type. In this study, the power generation profit and surplus thermal energy are measured according to the operation of the generator, and the thermal energy is traded according to the demand of the customer to calculate the profit and loss including the heat and evaluate the economic efficiency. As a result of the study, it is relatively profitable to reduce the generation of the generator under the condition that the electricity rate is low and the gas rate is high, while the basic charge is not increased. On the contrary, if the electricity rate is high and the gas rate is low, The more you start up, the more profit you can see. These results show that even a cogeneration power plant with a low economic efficiency due to a low "spark spread" has sufficient economic value if it can sell more than a certain amount of heat energy from a nearby customer and adjust the applied power through peak management.

• Food Science and Preservation
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• v.30 no.3
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• pp.395-404
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• 2023

Essential oil (EO) was extracted from the peel of Citrus hystrix DC. originating from Tinh Bien, An Giang province (Vietnam), using steam distillation. The study aimed to determine some physicochemical properties of Citrus hystrix peel EO (ChpEO), including the acid value (AV), saponification value (SV), ester value (EV), density, specific gravity, and freezing point. The chemical composition was also analyzed by gas chromatography-mass spectrometry (GC-MS). Compounds like β-pinene (30.19%), D-limonene (22.15%), and sabinene (21.37%), with antioxidant and antibacterial properties, had a relatively high content. The EO was also capable of inhibiting the growth of both Gram-positive and Gram-negative bacteria, including Pseudomonas aeruginosa (ATCC 27853), Staphylococcus aureus (ATCC 25923), Salmonella typhimurium (ATCC 13311), and Bacillus cereus (ATCC 11778) specifically.

• Transactions of the Korean hydrogen and new energy society
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• v.26 no.6
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• pp.638-644
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• 2015

This paper describes the continuing effort to analysis and design on dynamic and electrical behavior of gamma-type free piston Stirling engine/generator with dual-opposed linear generator for domestic micro-CHP (Combined Heat and Power) system. The double acting Stirling engine/generator has one displacer and two power piston which are supported by flexure springs. Two power pistons oscillate with symmetric sinusoidal displacement and are connected with moving magnet type linear generators for power generation. To operate Stirling engine/generator, combustion heat of natural gas is supplied to hot-end and heat is rejected from cold-end by cooling water. The temperature difference across the displacer induces the oscillating motion, and it can be explained with mass-spring vibration system. The purpose of this paper is to describe the design process of linear generator for the double acting free-piston Stirling engine.

• Journal of Korean Public Health Nursing
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• v.8 no.1
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• pp.73-83
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• 1994

This study was conducted to investigate rural residents' health status and lifestyle before inputing the health promotion services in CHP post juridiction area. For the survey. questionaire survey was done during the period from September 1993 to October 1993. Questionare was composed 14 items of general characteristics and 12 items of health age. Respondents were 119 residents among 300 residents in a rural area. For the analysis. descriptive statistics were used by calculating frequencies. percentages and $x^2-test$ Were employed to test the differences and the statistical significance. The major results are as follows; 1. Characteristics of the objects: The sex $61.0\%$ of female. the age was $36.0\%$ of over the fifties. the educational background was $47.4\%$ of elementary graduation. the marital status was $94.9\%$ of married and the monthly income was $35.3\%$ of less than 600,000 won. 2. Health status of the objects; Hepatitis antibody was possessed only $6.2\%$. hypertension was $27.3\%$. pulse rate and disease status were. for the most part, normal. 3. Health care status of the objects: They didn't use $74.1\%$ of medical services for the two weeks and regular health check-up. 4. Health behavior of the objects: The diet was $78.1\%$ of intaking meats and fish below 4 times for 1 week, no smoking was $66.1\%$. drinking was $70.83\%$ below two and half times for 1 week, life satisfaction was $21.8\%$. stress management was $41.5\%$ and exercise for health was $25.2\%$. 5. Experience of common cold for 3 years was $46.2\%$. hypertention by sex was $8.7\%$ of males and $19.4\%$ of females and diabetus was $1.7\%$ 6. Helth behavior by educational background didn't do in low educational background. 7. Health age of the objects was $62.3\%$ of $+1\~+4$ than actual age.

• Journal of Korean Academy of Rural Health Nursing
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• v.4 no.2
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• pp.110-119
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• 2009

Purpose: This study was done to identify Community Health Practitioner's (CHP's) perception of barriers to research utilization Method: Participants were 153 CHPs working in Chungbuk Province. Modified Barriers Scale was utilized in the research, and 4 sub-scales were nurse factor, organization factor, research factor and communication factor. Data was analyzed by using SPSS/WIN12.0. Results: Research factor showed the highest barrier score among four sub-scales, and nurse factor was the lowest. CHPs with membership in any nursing academic society showed lower scores on the four sub-scales. Those who had taken a course related to research were less likely to see the research factor or communication as barriers. Barriers to research utilization were not associated with work experience years or to demographics. Conclusion: It is highly recommended that CHPs be trained in research methods and evidence-based practice and that research articles be written more clearly.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.361-364
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• 2009

KEPRI has studied planar type SOFC stacks using anode-supported single cells and kW class co-generation systems for residential power generation. A 1kW class SOFC system consisted of a hot box part, a cold BOP part and a water reservoir. A hot box part contains a SOFC stack made up of 48 cells with $10{\times}10cm^2$ area and ferritic stainless steel interconnectors, a fuel reformer, a catalytic combustor and heat exchangers. Thermal management and insulation system were especially designed for self-sustainable operation. A cold BOP part was composed of blowers, pumps, a water trap and system control units. When a 1kW class SOFC system was operated at $750^{\circ}C$ with hydrogen, the stack power was 1.2kW at 30 A and 1.6kW at 50A. Turning off an electric furnace, the SOFC system was operated using hydrogen and city gas without any external heat source. Under self-sustainable operation conditions, the stack power was about 1.3kW with hydrogen and 1.2kW with city gas respectively. The system also recuperated heat of about 1.1kW by making hot water. Recently KEPRI developed stacks using $15{\times}15cm^2$ cells and tested them. KEPRI will develop a 5 kW class CHP system using $15{\times}15cm^2$ stacks by 2010.

• Korean Chemical Engineering Research
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• v.48 no.1
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• pp.39-44
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• 2010

Economic feasibility of power generation system using waste woody biomass in a circulating fluidized bed combustor has been investigated. Effects of important variables such as capital investment, cost of waste wood, certified emission reduction(CER), system marginal price(SMP) on the benefit of business have been analyzed. Internal rate of return(IRR) was predicted as 16.67%, which implicates the business is promising based on the assumptions such as SMP of 99 Won/kWh, capital cost of 10.65 billion won, and complimentary providing of waste wood. Major factors affecting the benefit of business were as follows; system marginal price, operational rate, capital investment, expenditure of waste wood, certified emission reduction. In addition, it must be necessary to consider CHP power plant providing steam as one of the means to diversify sales network, for the management of the business risk.

• Journal of Acupuncture Research
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• v.19 no.5
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• pp.10-27
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• 2002

연구목적 : 면역억제와 활성 작용을 지닌 것으로 알려진 녹용약침(CPH)을 type II collagen 유발 관절염 (CIA) 백서와 인산이온 유발 연골세포의 세포사에 있어 보호활성 효과를 연구하였다. 연구방법 : 7주된 암컷 Sprague-Dawley 쥐를 collagen으로 관절염을 유발시킨 후 CPH의 효과를 관절염 점수, 체중감소 등의 평가기준으로 검정하였다. CPH는 일주일에 5번씩 각각 10, 20, 30 및 $100{\mu}g/kg/day$의 용량으로 양측 신수혈에 주입하였다. 연구결과 : 1. 300 mg/kg/day CPH처리로 관절염점수의 감소를 기초로 한 collagen 유발 관절염의 발생을 완전히 억제하였으며 관절염 점수상에서 CPH의 효과작인 용량은 64 mg/kg이었다. 2. CHP는 쥐의 간에 있는 DHO-DHase 활성을 $Ki=843{\pm}43{\mu}g/ml$의 비교적 높은 비활성으로 억제하였다. 3. 관절염관련 세포의 증식억제활성을 검정한 결과 CPH의 항 증식효과는 세포주기 S기에서 정지시키는 활성을 나타내었다. 4. 쥐의 늑연골로부터 완전히 최종 분화된 비대연골세포를 분리 배양하여 3~5mM/L Pi를 첨가함으로서 세포사멸을 측정하였다. $10{\mu}g/ml$ CPH 처리에 의한 보호(억제) 효과가 Pi-유발 연골세포의 세포사에 대한 Na-Pi cotransport의 경쟁적 저해제로 알려진 phosphonoformic acid(PFA)의 억제활성과 상응하는 수준으로 CPH의 활성을 확인하게 되었다.