• Journal of Power Electronics
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• 제16권2호
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• pp.666-674
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• 2016

In this paper, a high efficiency satellite electrical power supply system is proposed. The increased efficiency of the power supply system allows for downscaling of the solar array and battery weight, which are among the most important satellite design considerations. The satellite power supply system comprises two units, namely a generation unit and a storage unit. To increase the efficiency of the solar array, a maximum power point tracker (MPPT) is used in the power generation unit. In order to improve the MPPT performance, a novel algorithm is proposed on the basis of the hill climbing method. This method can track the main peak of the array power curve in satellites with long duration missions under unpredicted circumstances such as a part of the array being damaged or the presence of a shadow. A lithium-ion battery is utilized in the storage unit. An algorithm for calculating the optimal rate of battery charging is proposed where the battery is charged with the maximum possible efficiency considering the situation of the satellite. The proposed system is designed and manufactured. In addition, it is compared to the conventional power supply systems in similar satellites. Results show a 12% increase in the overall efficiency of the power supply system when compared to the conventional method.

• 전기학회논문지
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• 제64권5호
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• pp.708-717
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• 2015

This paper proposes a new reduction scheme of circulating current when two units of BESS (Battery Energy Storage System) are operated in parallel with conventional droop control. In case of using conventional droop, the terminal voltage of each BESS are not equal due to the unequal line impedance, which causes the circulating current. The operation performance of BESS is critically dependant on the circulating current because it increases system losses which causes the increasement of required system rating. This paper introduces a new reduction scheme of circulating current in which the terminal voltage difference of each BESS is compensated by adding feed-forward path of line voltage drop to the droop control. The feasibility of proposed scheme was first verified by computer simulations with PSCAD/EMTDC software. After then a hardware prototype with 5kW rating was built in the lab and many experiments were carried out. The experimental results were compared with the simulation results to confirm the feasibility of proposed scheme. Two parallel operating BESS with proposed scheme shows more accurate performance to suppress the circulating current than those with the conventional droop control.

• Nuclear Engineering and Technology
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• 제55권6호
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• pp.2288-2297
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• 2023

Current designs of both large reactor units and small modular reactors utilize a nuclear fuel with increasing enrichment. This increasing demand for better nuclear fuel utilization is a challenge for nuclear fuel handling facilities. The operation with higher enriched fuels leads to reduced reserves to legislative and safety criticality limits of spent fuel transport, storage and final disposal facilities. Design changes in these facilities are restricted due to a boron content in steel and aluminum alloys that are limited by rolling, extrusion, welding and other manufacturing processes. One possible solution for spent fuel pools and casks is the burnup credit method that allows decreasing very high safety margins associated with the fresh fuel assumption in spent fuel facilities. This solution can be supplemented or replaced by an alternative solution based on placing the neutron absorber material directly into the fuel assembly, where its efficiency is higher than between fuel assemblies. A neutron absorber permanently fixed in guide tubes decreases system reactivity more efficiently than absorber sheets between the fuel assemblies. The paper summarizes possibilities of fixed neutron absorbers for various nuclear fuel and fuel handling facilities. Moreover, an absorber material was optimized to propose alternative options to boron. Multiple effective absorbers that do not require steel or aluminum alloy compatibility are discussed because fixed absorbers are placed inside zirconium or steel cladding.

• Asian-Australasian Journal of Animal Sciences
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• 제28권6호
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• pp.807-815
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• 2015

The present study aimed at evaluating the intensity of Tifton 85 conditioning using a mower conditioner with free-swinging flail fingers and storage times on dehydration curve, fungi presence, nutritional value and in vitro digestibility of Tifton 85 bermudagrass hay dry matter (DM). The dehydration curve was determined in the whole plant for ten times until the baling. The zero time corresponded to the plant before cutting, which occurred at 11:00 and the other collections were carried out at 8:00, 10:00, 14:00, and 16:00. The experimental design was randomised blocks with two intensities of conditioning (high and low) and ten sampling times, with five replications. The high and low intensities related to adjusting the deflector plate of the free iron fingers (8 and 18 cm). In order to determine gas exchanges during Tifton 85 bermudagrass dehydration, there were evaluations of mature leaves, which were placed in the upper middle third of each branch before the cutting, at every hour for 4 hours. A portable gas analyser was used by an infrared IRGA (6400xt). The analysed variables were photosynthesis (A), stomatal conductance (gs), internal $CO_2$ concentration (Ci), transpiration (T), water use efficiency (WUE), and intrinsic water use efficiency (WUEi). In the second part of this study, the nutritional value of Tifton 85 hay was evaluated, so randomised blocks were designed in a split plot through time, with two treatments placed in the following plots: high and low intensity of cutting and five different time points as subplots: cutting (additional treatment), baling and after 30, 60, and 90 days of storage. Subsequently, fungi that were in green plants as well as hay were determined and samples were collected from the grass at the cutting period, during baling, and after 30, 60, and 90 days of storage. It was observed that Tifton 85 bermudagrass dehydration occurred within 49 hours, so this was considered the best time for drying hay. Gas exchanges were more intense before cutting, although after cutting they decreased until ceasing within 4 hours. The lowest values of acid detergent insoluble nitrogen were obtained with low conditioning intensity after 30 days of storage, 64.8 g/kg DM. The in vitro dry matter of Tifton 85 bermudagrass did not differ among the storage times or the conditioning intensities. There was no fungi present in the samples collected during the storage period up to 90 days after dehydration, with less than 30 colony forming units found on plate counting. The use of mower conditioners in different intensities of injury did not speed up the dehydration time of Tifton 85.

• 한국식품과학회지
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• 제39권4호
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• pp.380-385
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• 2007

수확직후 흙이 묻은 수삼을 저장${\cdot}$유통시키는 기존방식을 개선키 위한 기초연구로 표면을 세척한 수삼의 저장 중 품질변화를 흙이 묻어 있는 수삼과 비교하였다. 이를 위하여 수확직후 수삼과 이를 불과 솔로 세척한 후 표변의 수분을 제거한 수삼을 각각 0.05 mm 두께의 PE 필름으로 MA 포장한 후 0, 5, 10, $20^{\circ}C$에서 저장하면서 중량감소, 변질률 , 관능적 품질, 호흡률, 경도 및 미생물의 변화를 조사하였다. $0^{\circ}C$에서 45일간 저장 시 세척수삼의 중량 감소율은 대조구의 수삼과 거의 유사하였으나 $5^{\circ}C$ 및 $10^{\circ}C$에서 저장하였던 경우 세척수삼이 대조구의 수삼에 비해 각각 46% 및 37% 정도 낮았다. 변질률도 세척 수삼이 대조구에 비해 낮았는데 $10^{\circ}C$에 저장한 대조구의 수삼이 세척 처리하여 $20^{\circ}C$에서 동일기간 저장하였던 수삼에 비해 변질이 빨랐다. $10^{\circ}C$에서 45 일간 저장하였던 세척수삼의 항목별 관능적 평점은 6.8-8.2점 범위이었던 반면 대조구는 5.7-6.9점 범위를 나타내었다. 호흡률은 세척수삼이 저장 초기 대조구에 비해 약간 높았지만 저장 중에는 차이를 보이지 않았다. 세척수삼은 대조구에 비해 생균수는 0.87 log unit, 곰팡이 및 효모는 1.55 log unit, 대장균군의 경우 0.95 log unit 낮은 값을 보였으며 이러한 경향은 저장 기간 동안 유지되었다.

• 한국축산식품학회지
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• 제32권1호
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• pp.84-90
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• 2012

본 연구는 인산염의 첨가와 침지가 저지방 소시지의 저장기간에 따른 품질 및 저장성을 평가하기 위해 실시하였다. 저지방 소시지에 0.4% STPP를 첨가하고, 10% TSP 용액에 침지함에 따라 pH값이 증가하였다. STPP의 첨가에 따라 적색도가 감소하는 반면, 10% TSP 침지구의 황색도는 증가하였다(p<0.05). 저장기간이 경과함에 따라 명도는 유의적으로 감소한 반면 적색도는 유의적으로 증가하였다(p<0.05). 약 5 Log CFU/g로 접종된 Listeria monocytogenes(LM) 균수는 저장기간이 경과함에 따라 4주에 8.03-8.22 Log CFU/g로 나타났고 8주에는 7.89 Log CFU/g로 약간 감소했다. 접종된 저지방 소시지의 저장 중 총균과 LM균의 성장은 10%의 TSP 침지에 의해 pH의 증가로 유의적으로 더 촉진된 것으로 판단된다. 이와 같은 결과를 종합하면 인산염 첨가 및 침지는 pH와 색도(명도와 황색도)에 영향을 주었으며 저장기간 중 뚜렷한 항균 및 항산화 효과는 없었다.

• 한국축산식품학회지
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• 제35권6호
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• pp.807-814
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• 2015

This study investigated the effect of added freeze-dried mulberry fruit juice (FDMJ) (1, 3 and 5%) on the antioxidant activity and fermented characteristic of yogurt during refrigerated storage. A decrease in pH of yogurt and increase in acidity was observed during fermentation. The yogurts with FDMJ exhibited faster rate of pH reduction than control. Initial lactic acid bacteria count of yogurt was 6.49-6.94 Log CFU/g and increased above 9 Log CFU/g in control and 1% in FDMJ yogurt for 24 h. The total polyphenol and anthocyanin content of FDMJ yogurt was higher than that of control due to the presence of phytochemical contents in mulberry. Moreover, antioxidant activity such as DPPH and reducing power was highest 5% FDMJ yogurt. During cold storage, pH decreased or remained constant in all yogurts with values ranging from 4.08 to 4.78 units. In sensory evaluation, the score of 1% FDMJ yogurt was ranked higher when compared with other yogurts. It is proposed that mulberry fruit juice powder can be used to improve sensory evaluation and enhance functionality of yogurt.

• 한국생활과학회지
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• 제14권2호
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• pp.321-330
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• 2005

PHB/chitosan 필름의 항균성 실험에서는 chitosan 필름이 실험에 사용한 세균과 곰팡이 모두에 대해 가장 높은 항균력을 나타내었고 PHB(L)도 Fusarium solani KCTC 6636와 Penicillium citreonigrum KCTC 6927에 대해 높은 항균성을 나타내었다. 식빵포장 실험에서는 chitosan이 첨가된 필름으로 포장된 식빵이 저장기간 중 수분 보유율이 좋은 것으로 나타났으며, 식빵의 색도에 있어서는 포장 필름의 종류에 관계없이 $L^*$과 $b^*$는 저장기간 동안 증가하였고 $a^*$는 저장기간 동안 거의 변화하지 않았다. Chitosan 필름과 PHB(L) 필름으로 포장한 식빵의 TBA가는 저장기간 중 적게 증가하여 이들 식빵에서 지질의 산화가 크게 일어나지 않았음을 확인할 수 있었다. 식빵의 질감특성 분석에서는 PHB(M), PHB(L), chitosan 필름으로 포장한 식빵이 PHB, PHB(H)로 포장한 식빵보다 유의적으로 탄력성이 큰 것으로 나타났다. 식빵 저장 중 미생물 수의 변화에서는 chitosan의 항균력으로 chitosan이 함유된 필름으로 포장된 식빵에서 미생물 수가 적게 나타났다. 따라서 전체적으로 볼 때 식빵 포장용으로 PHB(M), PHB(L), chitosan 필름이 PHB(H), PHB 필름보다 더 적합한 것으로 판단되었다.

• 한국비블리아학회지
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• 제5권1호
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• pp.85-105
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• 1981

Information is an essential factor leading the rapid progress which is one of the distinguished characteristics in modem society. As more information is required and as more is supplied by individuals, governmental units, businesses, and educational institutions, the greater will be the requirement for efficient methods of communication. One possibility for improving the information dissemination process is to use computers. The capabilities of such machine are beginning to be used in the process of Information storage, retrieval and dissemination. An important problems, that must be carefully examined is whether one technique for information retrieval is better for worse than another. This paper examines problem of how to evaluate an information retrieval system. One specific approach is a cost accounting model for use in studying how to minimize the cost of operating a mechanized retrieval system. Through the use of cost analysis, the model provides a method for comparative evaluation between systems. The general cost accounting model of the literature retrieval system being designed by this study are given below. 1. The total cost accounting model of the literature retrieval system. The total cost of the literature retrieval system = (the cost per unit of user time X the amount of user time) + ( the cost per unit of system time X the amount of system time) 2. System cost accounting model system cost = (the pre-search system cost per unit of time X time) + (the search system cost per unit of time X time) + (the post search system cost per unit of time X time) 1) Pre-search system cost per unit of time = cost of channel per unit time + cost of central processing unit per unit time + cost of storage per unit time 2) Search system cost per unit of time = comparison cost + document representation cost. 3) Post-search system cost per unit of time. = cost of channel per unit time + cost of central processing unit per unit time + cost of storage per unit time 3. User cost accounting model Total user cost = [pre-search user cost per unit of time X (time + additional time) ] + [search user cost per unit of time X (time + additional time) ] + [post-search user cost per unit of time X (time + additional time) ].

• 한국축산식품학회지
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• 제30권4호
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• pp.603-608
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• 2010

This study investigated the effects of electron beam irradiation on pathogens, quality, and functional properties of shell eggs during storage. A 1st grade 1-d-old egg was subjected to electron beam irradiation at 0, 1, 2, and 3 kGy, after which the number of total aerobic bacteria, reduction of inoculated Escherichia coli and Salmonella Typhimurium, egg quality, and functional properties were measured. Electron beam irradiation at 2 kGy reduced the number of E. coli and S. Typhimurium cells to a level below the detection limit (<$10^2$ CFU/g) after 7 and 14 d of storage. Egg freshness as measured by albumen height and the number of Haugh units was significantly reduced by 1-kGy irradiation. The viscosity of irradiated egg white was also significantly decreased by increased irradiation, whereas its foaming ability was increased. Electron beam irradiation also increased lipid oxidation in egg yolks. These results suggest that electron beam irradiation reduces the freshness of shell eggs while increasing the oxidation of egg yolk and improving important functional properties such as foaming capacity. Electron beam irradiation can also be applied to the egg breaking process since the irradiation reduces the viscosity of egg white, which can allow egg whites and yolks to be separated with greater efficiency.