• Proceedings of the KSR Conference
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• 2000.11a
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• pp.712-719
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• 2000

This paper presents a new algorithm to analyze a train voltages of multi-trains in auto-transformer-fed AC railway systems, using electrical equivalent change. The train current will be divided into circulation and return currents, and these current values are the same. By evaluating each current independently, the result will be more precise. The train current flows through the all auto-transformer corresponding to track impedance. In analyzing the railway system, the algorithm is based on the K.C.L, K.V.L, superposition and circuit separation method. Multi-train's voltages are determined by calculating the catenary voltage at each train's position and adding up these train's voltage drop. Case studies use a field operational data, show that tile proposed method is easily applied.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.39 no.2
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• pp.149-156
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• 1990

In DC electric railway systems, the feeding currrnt is not permitted to flow backward in almost all the substations and the pantograph voltages at the regenerating cars rise extremely by the voltage drop of the resistance of the feeder line. In order to prevent the overrise of the pantograph voltage in power regenerating cars, the squeezing circuits for the regenerative current are equipped and this leads to double losses, which are an extra worn-out of the brake-shoes and an ineffective use of regenerative power. In this study, the insertion of resistors in the feeder line system is proposed as a possible method for the effective utilization of the regenerative power in the electric railways. Also it is investigated how the output voltages of substations affect the effective use of regenertive capability. The investigation results show that the energy savings and the reduction of the worn-out of the brake-shoe can be achieved at the same time by the insertion of resistors in the feeder line system.

• Animal cells and systems
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• v.14 no.4
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• pp.297-303
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• 2010

To document the basic ecological aspects of Chaoborus species, which has never been reported in Korea, we attempted to identify the species, to monitor seasonal and vertical dynamics, and to elucidate trophic relations of the species in Sang-Chun reservoir. Using morphological characteristics, we identified the collected samples as C. flavicans. Also, we compared the distribution of C. flavicans, Daphnia rosea and chlorophyll a to observed seasonal dynamics. The increase of C. flavicans was observed 1-2 weeks after the increase of D. rosea. Survey of diel vertica migration patterns in the summer season showed that C. flavicans were in hypolimnion at daytime, but moved to the epilimnion at night. Finally, to determine trophic relationships in Sang-Chun reservoir, additional studies on the food web were undertaken by stable isotope analysis. Chaoborus flavicans I-II instars appear to be filter feeders based on carbon isotope values. Trophic levels of C. flavicans III-IV instars were shown to be higher than other zooplankto based on nitrogen isotope values.

• Journal of the Korean Society of Propulsion Engineers
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• v.4 no.3
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• pp.74-82
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• 2000

The concept and characteristics of the propulsion systems for the next generation flight vehicles are described in this paper, where Hey are grouped into air breathing engine, rocket engine and combined cycle engine according to the feeding system of oxidizer. Air breathing engine has its good reusability and superior performance at low altitude, but its usage is limited at high altitude due to the decreased air density. Rocket engine can be used over the wide range of altitude, but it has disadvantages in low specific impulse and high cost. The several types of combined cycle engine, which are being developed by the leading countries in the aerospace, are highlighted as a remarkable candidate for the next generation propulsion system.

• Asian-Australasian Journal of Animal Sciences
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• v.22 no.1
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• pp.57-71
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• 2009

Crop-livestock mixed farming systems depend on the efficiency with which nutrients are conserved and recycled. Home-grown forage is used as animal feed and animal excretions are applied to cultivated crop lands as manure. The objective of this study was to develop a mixed farming system model for dairy cattle in Japan. The model consisted of four sub-models: the nutrient requirement model, based on the Japanese Feeding Standards to determine requirements for energy, crude protein, dry matter intake, calcium, phosphorus and vitamin A; the optimum diet formulation model for determining the optimum diets that satisfy nutrient requirements at lowest cost, using linear programming; the herd dynamic model to calculate the numbers of cows in each reproductive cycle; and the whole farm optimization model to evaluate whole farm management from economic and environmental viewpoints and to optimize strategies for the target farm or system. To examine the model' validity, its predictions were compared against best practices for dairy farm management. Sensitivity analyses indicated that higher yielding cows lead to better economic results but higher emvironmental load in dairy cattle systems integrated with forage crop production.

• Journal of The Korean Society of Grassland and Forage Science
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• v.24 no.1
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• pp.43-52
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• 2004

This study was carried out to determine the effect of corn silage and roughage feeding systems on milk yield and milk compositions. The experimental design was allotted into 3 treatments according to the feeding systems of rice straw(rice straw＋concentrate: T1), corn silage(corn silage ＋ concentrate: T2) and TMR treatment(Total mixed rate : roughage ＋ concentrate: T3). This research was carried out from Oct. 1988 to Mar. 1999 at Kimcheon Kyungbook. The results obtained were summarized as follows: 1. The milk yield increased upon T2(31.9$\pm$3.2kg) ＞ T3(29.6$\pm$3.8kg) ＞ T1 treatment(22.5$\pm$2.0kg)(P<0.05), but cows with T2 and T3 produced the highest at third parity while T1 at forth parity. 2. The milk fat percentage was the highest at T3 treatment(3.79$\pm$0.31%), and on the other hand T1 treatment appeared the lowest percentage. Cow at 2nd parity produced the highest milk fat contend over the other parity. 3. There was no significant difference in protein content between treatments and parity, but T2 and T3 were higher than T1 4. Treatment did not affact content of SNF even though T2 and T3 of the SNF revealed to higher than T1. T5 was T3(12.51$\pm$0.57%)>T1(11.71$\pm$0.62%)>T2 treatment(11.52$\pm$0.55%). These were not significant. 5. Somatic cell counts were the highest at T1(39.6 ${\times}$ $10^4$cell/ml), but T2 treatment was the lowest as 28.7 ${\times}$ $10^4$ cell/ml. These results indicates that com silage(T2) and TMR treatment(T3) could be recommended

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.3
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• pp.463-472
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• 2003

Cassava (Manihot esculenta, Crantz), an annual tropical tuber crop, was nutritionally evaluated as a foliage for ruminants, especially dairy cattle. Cultivation of cassava biomass to produce hay is based on a first harvest of the foliage at three months after planting, followed every two months thereafter until one year. Inter-cropping of leguminous fodder as food-feed between rows of cassava, such as Leucaena leucocephala or cowpea (Vigna unculata), enriches soil fertility and provides additional fodder. Cassava hay contained 20 to 25% crude protein in the dry matter with good profile of amino acids. Feeding trials with cattle revealed high levels of DM intake (3.2% of BW) and high DM digestibility (71%). The hay contains tannin-protein complexes which could act as rumen by - pass protein for digestion in the small intestine. As cassava hay contains condensed tannins, it could have subsequent impact on changing rumen ecology particularly changing rumen microbes population. Therefore, supplementation with cassava hay at 1-2 kg/hd/d to dairy cattle could markedly reduce concentrate requirements, and increase milk yield and composition. Moreover, cassava hay supplementation in dairy cattle could increase milk thiocyanate which could possibly enhance milk quality and milk storage, especially in small holder-dairy farming. Condensed tannins contained in cassava hay have also been shown to potentially reduce gastrointestinal nematodes in ruminants and therefore could act as an anthelmintic agent. Cassava hay is therefore an excellent multi-nutrient source for animals, especially for dairy cattle during the long dry season, and has the potential to increase the productivity and profitability of sustainable livestock production systems in the tropics.

• Asian-Australasian Journal of Animal Sciences
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• v.23 no.12
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• pp.1614-1625
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• 2010

Two experiments were conducted to evaluate the use of fish silage prepared from Indian oil sardines, Sardinella longiceps, as partial replacement of soybean meal as a sole source of protein for growing broiler chickens. The main objective of Experiment 1, an ileal digestibility assay, was to assess the nutritional value of fish silage compared with soybean meal for feeding broiler chickens. The two test ingredients, soybean meal and dried fish silage, were incorporated into semi-synthetic diets, as the only component containing protein. The ileal digestibility coefficients of amino acids of fish silage were considerably higher than those of soybean meal (p<0.001). The lower digestibility of amino acids from soybean meal was related to the presence of anti-nutritional factors such as trypsin inhibitors. Fish silage had higher levels of sulphur-containing amino acids than soybean meal. The objective of Experiment 2, a growth study, was to evaluate the effect of feeding fish silage on performance and meat quality characteristics of broiler chickens raised under closed and open-sided housing systems. Four diets containing various levels of fish silage (0, 10, 20 and 30%) were evaluated. Daily feed intake, body weight gain and feed conversion ratio were measured. At the end of Experiment 2, 96 birds were randomly selected and slaughtered to evaluate meat quality characteristics. Housing type had significant effects on feed intake and body weight gain (p<0.01). Birds in the open-sided house consumed 4.7% less amount of feed and gained 10.6% less than their counterparts in a closed house. Birds in both houses fed diets containing 10 and 20% fish silage gained more than birds fed 30% fish silage. The current study produced evidence that fish silage can replace up to 20% of soybean meal in broiler diets without affecting either growth performance or the sensory quality of broiler meat.

• The Journal of Society for e-Business Studies
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• v.18 no.1
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• pp.71-95
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• 2013

This study aims to validate the cost of building the infrastructure to commercialize online electric vehicles. For that purpose, we probe the cost to construct the necessary infrastructure for online electric vehicles regarding Seoul area public bus transit. OLEV and PEV are considered as alternative electric vehicle schemes, and each of them has their own cons and pros in terms of rechargeable battery cost and charger cost. An optimization model which minimizes the cost to install online electric bus feeding devices is proposed in order to compare the total costs of the two alternative schemes. We developed a Mixed Integer Programming model to locate the feeding devices of several different lengths at each bus stops. Furthermore, we implemented a computer simulator to obtain the parameters which will be used in the MIP model and a Web-based system which determines the optimal location of infrastructure for the whole city area from a result of the MIP model. The cost comparison result shows that the total cost of OLEV is cheaper than that of PEV considering the real data of Seoul area public transit, and, as a result, confirms the feasibility of the commercialization of OLEV.

• 한국생물공학회:학술대회논문집
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• 2000.04a
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• pp.550-553
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• 2000

The polymeric matrices made with poly(D,L-lactide-co-glycolide) were prepared using copolymer of poly(D,L-lactide) and poly(ethylene glycol) for application of drug delivery systems. Catalyst made use of stannous actoate. Particle size were differ greatly$(435.3{\pm}11.2{\sim}2284.1{\pm}188.5)$ that nanoparticle made use of according to solvent of various kinds. Polymer could a sharp distinction with copolymerized among LE-1, LE-2 and LE-3 of PLA and PEG of content that to examine $^1H-NMR$ of copolymer make refine and reprecipitation. Drug delivery effect at PLGA nanoparticle : PLA amount more then proved highly drug delivery amount that each LE-1, LE-2, LE-3, drug and solvent was 40mg, 20mg and 10mg. Drug delivery effect proved higher 20mg that change(10mg, 20mg, 40mg) at drug feeding amount with LE-2. The first a lot of drug proved delivery. LE-3 most lactide content proved much delivery since biodegradable on PLGA copolymer result from lactide. Also biodegradable rate was highest at LE-3 much of lactide content, because influence at biodegradable effect of lactide by inclusive of soft PEG.