• Journal of Hydrogen and New Energy
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• v.31 no.4
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• pp.372-379
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• 2020

Ammonia-hydrogen dual-fuel engine is a way to reduce greenhouse gas emission because ammonia and hydrogen are carbon-free fuels. In ammonia-hydrogen dual-fuel engine, hydrogen is supplied to improve the combustion characteristic of ammonia. In this study, an ammonia reformer was developed to supply hydrogen for 10 kW class ammonia-hydrogen dual-fuel engine. Thermodynamic characteristic and catalyst were investigated for ammonia reforming. Heat transfer was important for high ammonia conversion of ammonia reformer. 99% of ammonia conversion was obtained when 10 LPM of ammonia and 610℃ of hot gas were supplied to the ammonia reformer.

• Korean System Dynamics Review
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• v.9 no.2
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• pp.77-103
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• 2008

In order to respond dynamic changes in the global distribution system, the City of Pyeongtaek hope to expand port facilities and its hinterlands. In specific, it plans to designate these areas as free economic zones(FEZ), synthesizing the whole procedures from the development proposals to the operation and management. This paper examines the proposed urban development strategies focused on Pyeongtaek port which still reveals critical weakness as a gateway port backed up by the Seoul Metropolitan Areas. In order to enhance the global competitiveness of Pyeongtaek port, theoretically it depends on Geo Coyle's ACTIFELD methods. In addition to the traditional quantitative data, Coyle's ACTIFELD methods emphasize qualitative approaches, all of which would facilitate structural and systemic analyses of complex social phenomena. Applying ACTIFELD methods, this paper proposes that the City of Pyeongtaek should focus on three alternatives. That is, Pyeongtaek's policy priority should be given to ts he port city based on the key concepts of Supply Chain Management(SCM), Co-opetition supporting city, and waterfront-initiated urban development.

• Journal of Applied Tourism Food and Beverage Management and Research
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• v.9
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• pp.15-32
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• 1998

This experiment was carried out to evaluated biological availability of calcium inthe sea mustard, sea tangle and sea lettuce in the rats. Standard diets were made to supply 0.3% of Ca from CaCO3. Consequently, levels each test ingredients to be added were sets by their Cacontents. The ingredients such as sea mustard, sea tangle and sea lettuce wereadded to basal diet at levels of 15.23%, 12.66% and 23.42% respectively. Ingredients of the basal diet were soybean protein, corn oil, alpha-cellulose, methionine, choline cholride and vitamin and mineral premix. Dextrose was added at level up to 100%. Amount of soybean protein was adjustable to make all the diets isontrogenous. Rats were fed ad libitum the diets for 13 days. The results were summarized as follow: 1. Serum calcium levels of the sea mustard group(15.23%) were higher than those of the other group, but rats fed sea lettuce diets appeared to have the lowest value. 2. Ca concentration in tibia were lower in rats fed with sea lettuce, rather than in those with standard diet. 3. Ca concentration in femur of the rats fed seaweeds did not show any significant difference among groups. 4. In the liver weight in groups fed on the all experimental groups were decreased more than that in the case of the standard diet groups.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.6
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• pp.885-890
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• 2015

LLC resonant converter has been widely used because of its high efficiency and high energy density. In this paper, we designed a LLC resonant converter as the main power supply of the Nd:YAG pulse laser. First harmonic approximation (FHA) is used to model the LLC resonant converter. FHA equivalent circuit model and the transfer function of the LLC resonant converter is proposed. Soft start technology is also used to suppress the surge current. The laser output simulation test result is identical with the practical test, the laser energy of every pulse can reach up to 2.5J, and the pulse per second (PPS) can be adjusted from 6 to 18. The power system is verified stable and reliable by both of the simulation and experiment results.

• IE interfaces
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• v.24 no.3
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• pp.187-195
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• 2011

The automatic radiopharmaceutical module consists of several 2-way valves, couple of syringes, gas supply unit, heating(cooling) unit and sensors to control the chemical reagents as well as to help the chemical reaction. In order to control the actuators of radiopharmaceutical module, the process is tabulated using spread sheet as like excel. Unlike the common program, a trivial error is too critical to allowed in the process because the error can lead to leak the radioactive reagent and to cause the synthesis equipment failure during synthesizing. Hence, the synthesis process has been validated using graphic simulation while the operator checks the whole process visually and undergoes trial and error. The verification of the synthesis process takes a long time and has a difficulty in finding the error. This study presents a methodology to verify the process algebraically while the radiopharmaceutical module is converted to the network model. The proposed method is validated using actual synthesis process.

• Plant Journal
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• v.11 no.4
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• pp.28-37
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• 2015

본 논문에서는 2012년 시행된 신재생에너지공급의무화제도(RPS)에 따른 민간발전사들의 RPS 의무이행 현황을 알아보고 신재생에너지 공급인증서의 발급량 부족 및 거래시장에서의 심한 가격변동을 발전사업자들의 RPS 이행시 장애요인으로 분석하였다. RPS시행 이전에 추진하여 최근 준공한 동두천복합발전소에 대한 RPS이행방안 구성결과 연평균 약 334억원의 의무이행비용이 산출되었으며, 해당비용을 당초 사업타당성 검토 기초자료에 반영한 결과 내부수익률이 계획대비 31.8% 저하됨을 알 수 있었다. 신재생에너지 의무공급량의 비율이 해마다 증가하여 2024년부터는 전년도 발전량의 10%를 신재생에너지로 공급해야 하는데 RPS 의무공급 대상자로의 편입 초기부터 10%의 의무공급량을 이행해야 하는 신규 발전소의 경우 의무이행비용 과다로 사업성은 더욱 낮아지므로 의무공급량의 비율을 기존의 12단계에서 17단계로 완화하는 방안을 제시하였다. 즉, 동두천복합발전소의 이행비용을 기준으로 최초 2%부터 매년 0.5%씩 점진적으로 10%까지 높였을 때 내부수익률은 6.23%로써 처음부터 10%의 비율로 공급할 경우 산출한 내부수익률 4.18%보다 약 49%의 사업성 향상 효과를 얻을 수 있어 제도개선이 민간발전사업 촉진에 기여할 것으로 판단된다.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.2
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• pp.97-103
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• 2004

CHP system supplies electricity and heating together with high efficiency. Current utility's CHP system uses electric power by itself and sells thermal energy to KDHC(Korea District Heating Corporation). CHP's operation cost except sales revenue of heating was covered by the sale revenue of electricity. Thus Electric generation cost in district Heating CHP system has close relationship with the level of heating price. However, after the restructuring of electricity industry, the operation cost could not be covered by sales revenue of heating and electricity. This loss was compensated by energy subsidy program in the electric power industry infrastructure fund. This paper suggests reasonable evaluation and improvement methods of the loss calculation of CHP system utilizing the infrastructure fund efficiency In terms of the direction of support by the fund, it provides the methods to prevent inefficient operation through setting up the upper limit of subsidy and to improve the loss calculation. Moreover, it suggest fixed rate support by heating supply level and reducing subsidy gradually for an efficient operation of CHP system.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.4
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• pp.617-621
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• 2016

In addition to the energy storage facilities based on high power technologies, Electric double layer capacitors(EDLC) are today's candidate for power quality stabilization. However, its low energy density is often inhibiting factor for application of electric power industry. Hybrid supercapacitor is an promising energy storage device that positioned between conventional EDLC and Li-ion battery. This paper describes the preparation and characteristics of a hybrid supercapacitor and module for power quality stabilization. A cylindrical 3200F hybrid supercapacitor ($60{\times}74.5mm$) was assembled by using the $Li_4Ti_5O_{12}$ electrode as an anode and activated carbon as a cathode. It shows 2.5 times higher energy density than conventional EDLC with the same volume. In order to determine the characteristics of the hybrid supercapacitor Module for uninterruptible power supply (UPS), hybrid supercapacitor cells were connected in series with active balancing circuit. At even the high current density of 14A(10C), Module prepared by 18 cells showed the capacitance of 170F at 30~50V, suggesting the applicability for UPS.

• International journal of advanced smart convergence
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• v.9 no.1
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• pp.132-140
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• 2020

It is very important to use appropriate nutrition water for crop growth in hydroponic farming facilities. However, in many cases, the supply of nutrition water is not designed with a precise plan, but is performed in a conventional manner. We proposes a forecasting technique for nutrition water requirements based on a data analysis for optimal strawberry production. To do this, the proposed forecasting technique uses linear regression for correlating strawberry production, soil condition, and environmental parameters with nutrition water demand for the actual two-stage strawberry production soil. Also, it includes predicting the optimal amount of nutrition water requires according to the heterogeneous cultivation environment and variety by comparing the amount of nutrition water needed for the growth and production of different kinds of strawberries. We suggested study uses two types of section beds that are compared to find out the best section bed production of strawberry growth. The dataset includes 233 samples collected from a real strawberry greenhouse, and the four predicted variables consist of the total amounts of nutrition water, average temperature, humidity, and CO₂ in the greenhouse.

• Plant Journal
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• v.7 no.2
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• pp.44-51
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• 2011

Given the fact that the entire bituminous coal used for a boiler is imported, the supply of coal is often affected by the rise of international coal price. Moreover, coal suppliers have been diversified due to the competition among power generation companies for reducing costs and inexpensive sub-bituminous coal is used. As a result, boilers combustion conditions have been deviated from the initial boiler design. This requires the selection of adequate excessive air ratio for different combustion conditions to enhance the efficiency of boiler operation. The boiler efficiency has been identified through an examination on the change of excessive air ratio by mixed fuel in unit 8 of Dangjin power plant complex. In addition, an excessive air ratio was calculated based on the examination result. According to the study result, the adequate excessive air ratio was 13% when Macquarie and Powder river were mixed at a ratio of 5:5 and when Sonoma and Megaprima persada were mixed at a ratio of 5:5. When BHP Billiton and Powder river were mixed at a ratio of 4:6 and Centennial and Batubara were mixed at a ratio of 3:7, the adequate excessive air ratio was 11%.