• Journal of the Korean Solar Energy Society
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• v.31 no.5
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• pp.91-98
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• 2011

연료전지 차랑용에 있어서 공기 가습 및 감습의 중요성은 매우 크다. 특히 PEM(Proton Exchange Membrane)연료전지에서 수분평형은 총괄시스템성능에 큰 영향을 미치는 요소인데, 이에 관한 중요한 연구가 지금까지 광범위하게 수행되고 있다. 또한 차량과 같이 동적부하 연료전지를 활용하는 분야에 있어서, 전류의 흐름은 차량용 파워 부하에 크게 영향을 받는다. 따라서 전기적 흐름이 발생하면, 이에 따라 수분이 발생하게 되는데, 이러한 응축 수분은 예측이 되며, 수관리 시스템에서 이를 중요한 제어 기준으로 활용한다. 그러므로 적절한 제어방법을 선택하면 유입공기의 온도와 습도의 최적값을 얻을 수 있다. 따라서, 본 논문에서는 PEM 연료전지의 수관리를 위하여 수분전달 모델과 유전알고리즘(genetic algorithm)을 사용하는 제어방법에 초점을 두고 있다.

• Journal of Energy Engineering
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• v.25 no.2
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• pp.45-51
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• 2016

The pool water management system, which is installed for purification of the coolant in the pools and the primary cooling system of a research reactor, removes the decay heat from the reactor core when the primary cooling system stops. It also removes the heat generated from the irradiated objects in the service pool and the spent fuels in the spent fuel storage pool to keep the temperature of the pools within a limited value. In this study, the heat exchanger of the pool water management system is designed by CFD method using a commercial code Flowmaster, and the temperature of the pools is estimated along the time to conclude the design and operation method of the pool water management system.

• Journal of Korean Society of Forest Science
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• v.89 no.2
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• pp.256-259
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• 2000

D.B.H., height, crown length, crown width, crown form, crown area, and crown volume of dead and live trees were measured and the discriminant analysis was conducted to assess individual tree risk-rating in the pine forest seriously infested by the pine needle gall midge. Thecodiplosis japonensis. Crown length, crown form, crown area, and crown volume of live tree were significantly higher than those of dead tree, while D.B.H. and tree height were not different significantly. These results represent that the trees with higher and wider crown and larger crown volume have relatively higher probability to survive from the infestation by the pine needle gall midge. Variables selected in the functions of discriminant analysis were crown area, ratio of crown length, crown form, ratio of crown volume to crown area, and ratio of crown width.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2018.05a
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• pp.187-188
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• 2018

2004년 체결된 평형수관리협약은 2016년 9월 비준되어 2017년 발효 예정이었다. 그러나 발효 직전, 물리적으로 모든 선박에 평형수 처리장치를 설치하기 어렵다는 의견에 따라 2년 유예되었다. 따라서 수만 척의 선박은 2024년까지 평형수 처리장치를 설치해야 하며, 해당 시장의 규모는 약 40조원까지 성장할 것으로 추정된다. 그러나 우리나라에서 개발한 현재 평형수 처리장치는 IMO 형식승인을 받은 제품만 있을 뿐 USCG 형식승인을 받은 제품이 없어 평형수 처리시장을 선점하기에 어려움이 있다. 따라서 본 연구에서는 USCG 성능기준을 만족하는 평형수 처리기술 개발을 위하여 IMO와 USCG 성능기준의 차이를 비교하고, 현재 사용되고 있는 선박평형수 처리장치의 국내 및 세계 기술 수준을 비교 분석하여 자외선 발광 다이오드 및 이산화티타늄을 이용한 평형수 처리장치 개발방향을 제시한다.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.3
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• pp.325-332
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• 2014

In installing ballast water treatment system, the cost of the system is high and many technical aspects are to be considered and also it takes significant time to retro-fitting on the existing ships. In addition, in the current circumstance which the Ballast Water Management Convention has not been entered into force, the 28th IMO Assembly adopted a resolution to mediate the implementation schedule of the treatment systems. In the mean time, California State and New York State have declared more stringent discharge requirements of ballast water and are planning to implement them earlier than the schedule of the Convention. In these circumstances, the implication in the difference between ballast water treatment system manufacturers and ship owners need to be considered. In this study, through the review on the considerations when installing the system onboard, stringent requirements of United States of America, and determent or mediated implementation schedules of Convention and California and New York States, the author would like to suggest the strategy of concerned parties for anticipated entrry into force of the Convention and implementation of the stringent requirements of United States of America.

• Transactions of the KSME C: Technology and Education
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• v.5 no.2
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• pp.135-143
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• 2017

The domestic unique research reactor, HANARO (Hi-flux Advanced Neutron Application ReactOr), has been constructed with the open-pool, the core is submerged in, for the multi-purpose neutron application. The reactor has a primary cooling system to remove the fission heat from the core and its connected fluidic systems. Since the works are required at the reactor pool top as a characteristic of the research reactor, the radiation shall be minimized with the operation of the hot water layer system to avoid unnecessary radiation exposure on the workers during work at the pool top. Moreover, the pool water management system is connected to the reactor pool to maintain the pool temperature below $50^{\circ}C$ to minimize the uprising radioactive gas or impurity from the colder pool bottom. For the efficient flow rate of the PWMS, the thermal capacity of heat exchanger is selected with 260 kW in the normal operation condition. In this paper, the modeling is formulated to figure out whether or not each pool temperature maintains below the temperature limit and the calculation results show that the designed PWMS heat exchanger has enough capacity with the design margin regardless of the reactor operation mode.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2012.06a
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• pp.202-202
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• 2012

• Journal of Korean Society of Forest Science
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• v.82 no.3
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• pp.283-291
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• 1993

These studies were carried out to investigate water yield from small forested watersheds at Choosan Stream-Gauging Stations in Chollanam-do province from May 11, 1991 to December 31, 1992. The purpose of these studies was to obtain useful informations as distribution of precipitation, canopy interception, stemflow, throughfall and run-off from the small forested watersheds. The precipitation at Choosan from May to December, 1991 was 1,306.6mm and at Choosan from January to December, 1992 was 1,143.4mm. The rate of canopy interception in Pinus taeda stand is 24.3% and 27% in Pinus densiflora stand. The run-off rate from the watershed was 48.87% at Bukmoongol small forested watershed and 41.19% at Baramgol small forested watershed.

• Journal of Korean Society of Forest Science
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• v.44 no.1
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• pp.1-25
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• 1979

Six natural populations of Pinus densiflora S. et Z. as shown in the location map (Flg 1) were studied during 1978. The numerial pouplation codes, 13 to 18. The results of populations 1 to 12 were reported in previous papers. Following the study methods described before, 20 trees were sampled from each population and morpological characteristics such as stem forms, branching habit needle and wood properties investigated. The results are summerized as follows; 1. The mean stand ages were ranged from 36 to 97 of years. The growth performances of trees of population 14. 15 and 18 was similar, but 13, 16, and 17 seemed to be inferior more or less. 2. The ratios of clear bole length were 0.70 in population 18 as the highest but 0.28 for population 16 as the lowest. 3. The population 17 was considered to be a stand of the coarser branching habit having the crown index (The maximum crown diameter/the crown height) 158 though the branching angles were almost horizontal. 4. The differences were observed in the clear bole length ratios and crown-indices between population as shown In Fig. 3 and 4. 5. As to the serration density, number of stomata row and resin duct; the significant differences exist between individual trees within population and also between populations. 6. Population 18 shown resin duct index 0.119 as the maximum. 7. The patterns of diameter growth, based on the width of 10-year-ring segment unit(for example, the 1st segment denotes the with between pith center and 10th year ring and the 2nd one is from 11th to 20th ring and so on.), were alike among populations as shown in Fig 9. 8. Significant differences between population in mean summer wood percentage as well as in wood specific gravity was observed. The values of wood specific gravity were increased with the increase of ages in population 14, 18 however vice versa in population 13, 15, and 17. 9. The fiber length was mereased with the increased of age but no differences between populations as shown in Fig. 12.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.35 no.1
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• pp.16-22
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• 1990

Four near-isogenic lines of growth habit derived from the breeders' seeds of Oweolbori and Jogangbori were obtained, respectively. From the analysis of pedigree charts, the genes for the pertinent growth habit in Oweolbori and Jogangbori seemed to be derived from the Milyang 6 and Hiproly, or Joshushirohadaka, respectively. The spring habit grades of the isogenic lines were classified: Oweolbori #1 and #2, Jogangbori #1 and #2 as I : Oweolbori #3 and #4, Jogangbori #3 and #4 as III, respectively. The spring habit of Oweolbori #1 and #2 might be controlled by one pair of recessive gene, shsh. The photoperiodic response, earliness in a narrow sense, and ratio of heading retardation significantly different in the isogenic lines with the same genetic backgrounds. The heading mature time differed in the isogenic lines sown in fall.