• Journal of Fisheries and Marine Sciences Education
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• v.27 no.2
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• pp.488-504
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• 2015

The purposes of this research are to analyze and compare curriculum of vocational high schools. In order to complete the purposes, the method of curriculum document analysis was used. Analysis subjects are Meister high schools, Technical high schools and Electronic high schools operating electron-related departments in Daegu and Gyungsangbuk-do. The conclusions of this research are as follows: Firstly, the educational goals of the vocational high schools were largely to educate professional men. The educational goals of vocational high school need to be improved in terms of high school's general educational goals and character education. Secondly, curriculum of vocational high schools consists of general subjects and specialized subjects and the rates of them vary according to region and school type. Thirdly, there were various general subjects by region and school type. Each school needs to organize the subjects to suit the progress of their students and graduates. Finally, there is a need to review the scope and sequence of specialized subjects.

• Journal of Microbiology and Biotechnology
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• v.26 no.1
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• pp.110-119
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• 2016

High-solid anaerobic digestion of sewage sludge achieves highly efficient volatile solid reduction, and production of volatile fatty acid (VFA) and methane compared with conventional low-solid anaerobic digestion. In this study, the potential mechanisms of the better performance in high-solid anaerobic digestion of sewage sludge were investigated by using 454 high-throughput pyrosequencing and real-time PCR to analyze the microbial characteristics in sewage sludge fermentation reactors. The results obtained by 454 highthroughput pyrosequencing revealed that the phyla Chloroflexi, Bacteroidetes, and Firmicutes were the dominant functional microorganisms in high-solid and low-solid anaerobic systems. Meanwhile, the real-time PCR assays showed that high-solid anaerobic digestion significantly increased the number of total bacteria, which enhanced the hydrolysis and acidification of sewage sludge. Further study indicated that the number of total archaea (dominated by Methanosarcina) in a high-solid anaerobic fermentation reactor was also higher than that in a low-solid reactor, resulting in higher VFA consumption and methane production. Hence, the increased key bacteria and methanogenic archaea involved in sewage sludge hydrolysis, acidification, and methanogenesis resulted in the better performance of high-solid anaerobic sewage sludge fermentation.

• Journal of Power Electronics
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• v.12 no.1
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• pp.58-66
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• 2012

SRMs(Switched Reluctance Motors) are much interested in high speed applications due to the mechanical robustness, simple structure and high efficiency. In spite of many advantages of SRMs, a higher torque ripple discourages the adoption of SRMs in a high speed application. This paper presents a simple negative torque of tail current compensation scheme using a modified TSF(Torque Sharing Function) for the high speed SRMs. Because of the short commutation in the high speed region, the negative torque from the tail current makes the high torque ripple. In order to reduce and compensate the negative torque from tail current, the proposed control scheme produces an additional compensating torque with a reference torque in the active phase winding. And the compensating value is dependent on the tail current of the inactive phase winding. Furthermore, the switching signals of the outgoing phase are fully turned off to restrict the extended tail current, and the torque error of the outgoing phase is compensated by the incoming phase. The proposed modified TSF control scheme is verified by the computer simulations with 30,000[rpm] high speed 4/2 SRM. The simulation and experimental results show the effectiveness of the proposed control scheme.

• Journal of Auto-vehicle Safety Association
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• v.10 no.3
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• pp.38-44
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• 2018

Conventional brake system was used for passenger cars and SUV for a long time. However, the high performance brake system has strongly required because of increase of engine power and customer's favorites etc. In this paper, a new high performance brake system for Europe was proposed. For this system, the high performance caliper and disc were newly developed. The superiorities of the developed high performance brake system were verified via heat capacity, hydraulic stiffness, corrosion and harsh braking mode test. Also, the high performance caliper and disc for the light-weight were applied to AL-Alloy and can obtain the weight reduction effect of 2.9 kg per vehicle. Finally, a developed high performance brake system is expected to be used for realization of the high performance at the same platforms.

• Magazine of the Korea Concrete Institute
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• v.6 no.6
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• pp.135-142
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• 1994

The quality characteristics of concrete using super plasticizer in dornestlc rnarket are evaluat ed in order to put to practical use of high performance concrete with high mobility. high strength ard high durability. For this purpose, rune kmds of super plasticizer are compared and analyzed for the slump, air content. unit weight, water reducing percent and ratios of compressive strength wth admixture content. As a result, the optimum quantity of admixture content were obtained for ordinary and high strength concrete using super plasticizer.

• Proceedings of the KIEE Conference
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• 2006.04b
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• pp.278-280
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• 2006

In this paper, a novel type of auxiliary active snubbingcircuit assisted quasi-resonant soft-switching pulse width modulation inverter is proposed for consumer induction heating equipments. The operation principle of this high frequency inverter is described using switching modes and equivalent circuits. This newly developed series resonant high frequency inverter can regulate its high frequency output AC power under a principle of constant frequency active edge resonant soft- switching commutation by asymmetrical PWM control system. The high frequency power regulation and actual power conversion efficiency characteristics of consumer induction heating (IH) products using the proposed soft-switching pulse width modulation (PWM) series load resonant high frequency inverter evaluated. The practical effectiveness and operating performance of high frequency inverter are discussion on the basis of simulation and experimental results as compared with the conventional soft-switching high frequency inverter.

• Proceedings of the KIEE Conference
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• 1997.07f
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• pp.2246-2248
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• 1997

This paper presents a high-frequency inverter type high-voltage power supply for X-ray equipments. The high-voltage generator consist of an inverter unit including the SR(Series Resonance) type PSC(Phase-Shifted Control) PWM circuit adopting IGBT as the switching power device and high-voltage unit including the CW(Cockcroft Walton) circuit. When the X-ray equipment is radiographing at large power for a short time, this generator operates through feedback voltage mode control to obtain a high speed leading edge and low ripple. The operating modes and design consideration of the proposed power supply are given. Issues in the design of high-voltage divider for high voltage measuring. Experimental results are presented to verify the performance of the designed power supply for varying load conditions. The proposed apparatus has several advantages, e.g., the fast rising time of tube voltage, accuracy and reduced component size etc.

• Journal of Advanced Marine Engineering and Technology
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• v.30 no.1
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• pp.42-49
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• 2006

In this research. the diesel cycle was thermodynamically interpreted to evaluate the possibility of high efficiency by converting diesel engines to the high expansion diesel cycle, and general cycle features were analyzed after comparing these two cycles. Based on these analyses. an experimental single cylinder a long stroke with high expansion-diesel engine. of which S/B ratio was more than 3, was manufactured. After evaluating the base engine through basic experiments, a diesel engine was converted into the high expansion diesel engine by establish VCR device and VVT system Accordingly, the high expansion diesel cycle can be implemented when the quantity of intake air is compensated by supercharge and the effective compression ratio is maintained at its initial level through the reduction of the clearance volume. In this case, heat efficiency increased by $5.0\%$ at the same expansion-compression ratio when the apparent compression ratio was 20 and the fuel cut off ratio was 2. As explained above, when the atkinson cycle was used for diesel cycle, heat efficiency was improved. In order to realize high expansion through retarding the intake value closing time, the engine needs to be equipped with variable valve timing equipment, variable compression ratio equipment and supercharged pressure equipment. Then a high expansion diesel cycle engine is realized.

• Journal of Sericultural and Entomological Science
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• v.9
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• pp.7-13
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• 1969

This experiment was carried out to know how to cut of the mulberry branches, formed by multi-stemmed pruning, which is together with the correlation between the leaf yield and total length, total diameter, or total length X total diameter of branches. The results are as follows: 1. In case of spring pruring, cutting off 5 cm high uniformly, cutting off thick one 10 cm high and cutting off slender one 5 cm high were best. 2. In case of summer pruning, cutting off upper part one 5 cm high and cutting off lower part one 10 cm high, cutting off thick one 10 cm high, slender one 5 cm high, 5 cm high uniformly were best. 3. As the result of this experiment, cutting off all the branches 5 cm high uniformly was available.

• The Korean Journal of Food And Nutrition
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• v.23 no.4
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• pp.562-569
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• 2010

This study was conducted to investigate the hypocholesterolemic effects of porphyran and insoluble dietary fiber isolated from laver in rats fed high fat diet containing 1% cholesterol, 0.25% sodium cholate and 12% lard. Rats were fed, ad libitum, diets containing 5% diet fiber as cellulose(normal control or high fat control), porphyran or insoluble dietary fiber for 4 weeks. Among the groups fed high fat diet, liver weight was significantly lower in high fat porphyran group than high fat control. Plasma GOT, GPT, total cholesterol, cholesteryl ester, LDL-cholesterol and liver total cholesterol concentration were significantly lower in high fat porphyran group than high fat control. The feeding of porphyran significantly increased fecal cholesterol and bile acid excretion. The feeding of insoluble dietary fiber had no significant effect on either plasma or liver cholesterol levels, although fecal cholesterol level in the insoluble dietary fiber group was significantly higher than that in the high fat control. The results indicate that porphyran isolated from the laver may exert their hypocholesterolemic effect by increasing excretion of fecal bile acid and cholesterol.