• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.385-392
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• 2008

Modern city have had a lot of high-rise building in high standards and multi-level performance. Using of city space reach better stages by using integration. These skyscraper have increased working load on ground. that building is efficiently designed for that soil capacity is well applied. With material side, big size pile, high strength concrete and high strength steel is used for that getting enough lobby space and resisting load increased of high-rise building. limit load test and load transmitted test can make soil capacity optimized. By the way, method of measuring pile capacity is more advanced and bigger. pile type applied by high rise building have underground excavation space, also reflect regional soil property and have some fact reviewed. A lot of high rise building recently is built as land mark in Seoul, Busan and Incheon. about method of measuring capacity of foundation pile, example of construction field is compared and reviewed.

• Proceedings of the KIPE Conference
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• 2006.06a
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• pp.200-202
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• 2006

In this paper, a novel type of auxiliary active snubbing circuit 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 KIPE Conference
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• 2005.07a
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• pp.754-757
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• 2005

액정 디스플레이 (LCD: Liquid Crystal Display)의 광원은 주로 냉음극 방전램프 (CCFL: Cold Cathode Fluorescent Lamp)가 사용되고 있으며, 19인치급 이하의 LCD 백라이트 인버터의 램프 구동방식은 가장 일반적인 램프 구동방식인 H-L(High-Low) 방식을 채택하여 사용하고 있다. 그러나 21인치 이상의 중 ${\cdot}$ 대형 LCD 백라이트 인버터는 소형 LCD 에 비해 보다 높은 구동 전압 ${\cdot}$ 전류가 필요함에 따라 기존의 H-L(High-Low) 방식이 아닌 H-H(High-High) 방식 사용하고 있다. 본 논문에서는 대형 LCD 백라이트 인버터에 주로 사용되고 있는 H-H(High-High) 방식을 압전 인버터(Piezoelectric Inverter)에 적용하여 H-L(High-Low) 램프구동 방식과 비교 하였으며, H-H(High-High) 램프구동방식을 통한 멀티램프 구동과 효율, 휘도가 우수함을 검증하였다.

• Journal of Fisheries and Marine Sciences Education
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• v.25 no.2
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• pp.393-404
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• 2013

In order to improve the employment rate of graduates in maritime and fisheries high schools, we investigated the employment situations of the those graduates for the last 8 years. The results were as follows, The ratio of graduates in maritime and fisheries high schools to total graduates of on-board departments are 69.1% and 30.9% respectively. The on-board employment rate of maritime high schools and fisheries high schools graduates are 63.2% and 26.7% respectively. Nearly all of the maritime high schools students were employed to merchant ship and fisheries high schools students were employed to merchant ship 77.2% and only 22.8% of them got a job on fisheries ship. The ratio of getting a job in maritime high schools to ocean-going ship was 76.7%, that was the highest ratio and the ratio of fisheries high schools got a job to ocean-going ship was 55.1%. The on-board career of maritime high schools graduates was 1~5 years, which took 86.4% of all careers and that of fisheries high schools was less than 1 year, which took 60.0% of all careers. We should make the various efforts to improve the employment rate of getting job to fisheries ship in the fisheries high school graduates.

• International Journal of High-Rise Buildings
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• v.3 no.3
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• pp.215-221
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• 2014

Ultra-high strength concrete and high tensile steel are becoming very attractive materials for high-rise buildings because of the need to reduce member size and structural self-weight. However, limited test data and design guidelines are available to support the applications of high strength materials for building constructions. This paper presents significant findings from comprehensive experimental investigations on the behaviour of tubular columns in-filled with ultra-high strength concrete at ambient and elevated temperatures. A series of tests was conducted to investigate the basic mechanical properties of the high strength materials, and structural behaviour of stub columns under concentric compression, beams under moment and slender beam-columns under concentric and eccentric compression. High tensile steel with yield strength up to 780 MPa and ultra-high strength concrete with compressive cylinder strength up to 180 MPa were used to construct the test specimens. The test results were compared with the predictions using a modified Eurocode 4 approach. In addition, more than 2000 test data samples collected from literature on concrete filled steel tubes with normal and high strength materials were also analysed to formulate the design guide for implementation in practice.

• Asian-Australasian Journal of Animal Sciences
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• v.14 no.10
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• pp.1409-1418
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• 2001

Two trials were carried out during two different grazing seasons to evaluate effect of grass silage supplementation, when amount of pasture is limited on dry matter intake (DMI), milk production, and gross energetic efficiency (GEE) of grazed lactating cows on a high forage-based diet. Fifty-one Holstein cows were randomly assigned to one of two dietary treatments: high pasture group or high silage group. In the spring flush, pasture and silage DMI, milk yield, milk fat percentage, and GEE were not different between the dietary groups. After the spring flush, pasture and silage DMI were higher for the high silage group than for the high pasture group. After the spring flush, although these were the higher total DMI of the high silage group than the high pasture group, milk yield was significantly (p<0.05) higher for the high pasture group than the high silage group. Milk fat percentage tended to be higher for the high silage group than the high pasture group. The GEE was significantly (p<0.05) higher for the high pasture group than the high silage group during after the spring flush. This study indicated that supplementation of grass silage, especially after the spring flush, can have a significant effect of increasing of forage intake and maintenance of the milk fat percentage; but not increase milk yield and GEE.

• Journal of Electrical Engineering and Technology
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• v.12 no.4
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• pp.1503-1510
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• 2017

In this paper, a thermal analysis of a high speed induction motor with a PWM voltage source was performed by considering harmonic loss components. The electromagnetic analysis of the high speed induction motor was conducted using the time-varying finite element method, and its thermal characteristics were carried out using the lump-circuit method. Harmonic losses from tests in the high frequency region were divided into core loss and conductor loss components using various ratios, in order to determine the loss distributions for the thermal analysis. The results from both the calculations and experiment were validated using a high speed induction motor prototype operating at 20,000rpm.

• 한국초전도학회:학술대회논문집
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• v.9
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• pp.38-42
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• 1999

We prepared hish T$_c$ Josephson junctions that have different I$_c\;'s$ and R$_n\;'s$ and studied their microwave properties. We measured the current-voltage characteristics of the junctions under the irradiation of 22 GHz electromagnetic wave at various temperatures. from the Shapiro steps, we calculated the maximum detectable frequency and the microwave received power of the junctions. Increasing critical current values increase both maximum detectable frequency and sensitivity. However, increasing temperature increase sensitivity but decrease maximum detectable frequency.

• Journal of Information Display
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• v.4 no.4
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• pp.25-32
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• 2003

One of the important problems in ac PDP in recent years is the misfiring of ac PDP at high ambient temperatures which consequently degrades the image quality of the ac PDP. This may be due to the change of working gas pressure and/or MgO surface characteristics at high ambient temperatures. This paper deals with the effect of working gas pressure on the misfiring of ac PDP at high ambient temperature. From this study, we found that the main cause of the misfiring at high ambient temperature is the increase in discharge firing voltage induced by increased working gas pressure

• Proceedings of the KIEE Conference
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• summer
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• pp.630-632
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• 2004

본 논문에서는 전력 계통에서 보호기기로 사용되는 차단기의 50/60Hz 공용주파수 정격의 시험방법에 대하여 기술하였다. 그 과정으로 차단기의 개발시험 항목에 대한 시험목적, 전류투입차단시 차단기에 미치는 영향 및 국제적으로 적용되고 있는 관련 적용규격을 고찰하고 50 Hz 및 60 Hz 공용정격으로서 성능을 검증할 수 있는 방안을 제시한다.