• Journal of the Optical Society of Korea
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• v.13 no.1
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• pp.15-21
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• 2009

High-order harmonic generation from a solid surface affected by the contrast of a laser pulse was studied using an oscillating mirror model. High-order harmonics generated from solid surfaces have unusual properties such as spectral redshift, and an intensity difference between even- and odd-order harmonics which is not reported for high-order harmonics generated by a gas medium. We confirmed that high-order harmonics from solid surfaces have selectivity of polarization as well as cut-off extension and the enhancement of conversion efficiency proportional to laser intensity. And the principle of operation and the characteristics of a plasma mirror system developed for achieving high contrast laser pulses to pursue the experimental realization of high-harmonic generation from solid surfaces are reported. Energy fluence on the plasma mirrors is tunable between $10\;J/cm^2$ and $1000\;J/cm^2$ and around 1000 shots are available before the plasma mirrors require replacement.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.231-235
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• 2004

High performance 42 inch XGA PDP with high luminance of 1,000 cd/$m^2$ has been developed using high efficient electrode structure, discharge gas and closed barrier ribs. For high speed addressing with single scan technique, address discharge time lag was reduced over 40% with FAST driving scheme and new materials. High dark room contrast ratio of 5,000 : 1 was achieved and picture quality was improved using new algorithm for eliminating false contour and improving gray level linearity.

• Archives of Pharmacal Research
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• v.25 no.2
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• pp.178-183
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• 2002

A high molecular ar weight water-soluble chitosan (WSC) with an average molecular weight of 300 kD and a deacethylation level of over 90% was produced using a simple multi-step-membrane separation process. It is known that WSC prevents obesity induced by a high-fat diet. Consequently, this study investigated whether or not WSC improved the ovarian dysfunction caused by obesity in mice. The mice were fed a high density protein and lipid diet for weeks, followed by the administration of WSC at 480 mg/kg body weight per day for 4 days. Thereafter, the changes in body weight, ovulation rate, in vivo and in vitro fertilization and emboryonic development were measured . WSC markedly reduced the body weight of obese mice fed with a high-fat diet, but not in mice fed with a normal diet. WSC had siginificant effects on the ovulation rate, both the in vivo and in vitro fertilization rates and embryonic development. These results indicate an improvement in the ovarian and oviduct dysfunction caused by obesity, and suggest an adjustment in the internal secretions and metabolic functions.

• Journal of Applied Biological Chemistry
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• v.54 no.3
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• pp.197-205
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• 2011

This study was carried out to investigate the dietary effects of Monascus pilosus mycelial extract on obesity in high-fat with cholesterol-induced obese rat models. It was observed that M. pilosus mycelial extract contains $25.85{\pm}1.98mg%$ of total monacolin K without citrinin by highperformance liquid chromatography (HPLC). The rats were randomly divided into 2 groups; normal control and a high-fat with cholesterol diet group. The high-fat with cholesterol diet group was fed a 5L79 diet with an added 15% lard and 1% cholesterol supplemented diet for 3 weeks for induction of obesity. After induction, obesity was confirmed by checking obesity indexes, the animals were divided into 4 groups (n=5); first, the normal control (NC), and then taken from the obese model of rats, a high-fat with cholesterol diet obesity control group (HF), 0.5% M. pilosus mycelial extract supplemented high-fat with cholesterol diet group (MPMs), 2% conjugated linoleic acid supplemented high-fat with cholesterol diet group (CLA) for 7 weeks. Body weight gains, obesity indexes, and body fat contents in the experimental groups (MPMs and CLA) were decreased compared with HF group. Feed Efficiency Ratio (FER) in MPMs was significantly lower than that of HF without change of feed intake. These results suggested that the anti-obesity effects of the M. pilosus mycelial extracts (MPMs) could prevent obesity induced by high-fat with cholesterol diet possibly via inhibition of lipid absorption.

• Journal of the Korean Ceramic Society
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• v.55 no.6
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• pp.527-555
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• 2018

High-temperature thermal insulation materials challenge extensive oxide candidates such as porus $SiO_2$, $Al_2O_3$, yttria-stabilized zirconia, and mullite, due to the needs of good mechanical, thermal, and chemical reliabilities at high temperatures simultaneously. Recently, porous rare earth (RE) silicates have been revealed to be excellent thermal insulators in harsh environments. These materials display attractive properties, including high porosity, moderately high compressive strength, low processing shrinkage (near-net-shaping), and very low thermal conductivity. The current critical challenge is to balance the excellent thermal insulation property (extremely high porosity) with their good mechanical properties, especially at high temperatures. Herein, we review the recent developments in processing techniques to achieve extremely high porosity and multiscale strengthening strategy, including solid solution strengthening and fiber reinforcement methods, for enhancing the mechanical properties of porous RE silicate ceramics. Highly porous RE silicates are highlighted as emerging high-temperature thermal insulators for extreme environments.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.616-620
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• 2005

The technology of high-speed electrical machines is particularly relevant to applications involving electrical power generation and high-speed motors with high power density and high efficiency. Due to the development of improved materials for electrical machines, power electronic elements and design technology, the high-speed electrical machines are being rapidly introduced into industrial applications. The introduction of high-speed electrical machines has created a new market for electrical machines and will, as an application, contribute to the development of modern electrical machines. This paper deals with applications and market trends and KERI's activities in high-speed electrical machines.

• Proceedings of the KIEE Conference
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• 2006.10d
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• pp.125-128
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• 2006

This paper presents a novel type soft switching PWM power frequency AC-AC converter using bidirectional active switches or single phase utility frequency AC-high frequency AC matrix converter. This converter can directly convert utility frequency AC (UFAC, 50Hz/60Hz) power to high frequency AC (HFAC) power ranging more than 20kHz up to 100kHz. A novel soft switching PWM prototype of high frequency multi-resonant PWM controlled UFAC-HFAC matrix converter using antiparallel one-chip reverse blocking IGBTs manufactured by IXYS corp. is based on the soft switching resonance with asymmetrical duty cycle PWM strategy. This single phase UFAC-HFAC matrix converter has some remarkable features as electrolytic capacitor DC busline linkless topology, unity power factor correction and sine-wave line current shaping, simple configuration with minimum circuit components, high efficiency and downsizing. This series load resonant UFAC-HFAC matrix converter, incorporating bidirectional active power switches is developed and implemented for high efficiency consumer induction heated food cooking appliances in home uses and business-uses. Its operating performances as soft switching operating ranges and high frequency effective power regulation characteristics are illustrated and discussed on the basis of simulation and experimental results.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.857_858
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• 2009

On account of small size and light weight, a high-speed machine is regarded as a key technology for many future applications of drive systems. In high-speed applications, permanent magnet (PM) synchronous motors have a number of merits such as high efficiency and high power density. Accordingly, they are suitable for driving the air-blower of a fuel cell electric vehicle (FCEV) where space and energy savings are critical. Particularly, a surface-mounted PM motor of them is mainly used as a high-speed machine. However, the motor has a fatal flaw owing to a retaining can to maintain the mechanical integrity of a rotor assembly. The can results in the increase of magnetic air-gap length in the surface-mounted PM motor. Thus, in this paper, an interior PM motor is designed in order to drive the air-blower of FCEV instead of the surface-mounted PM motor, and the experimental results of two models are compared to verify the capability of the interior PM motor for a high-speed machine.

• Journal of environmental and Sanitary engineering
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• v.24 no.4
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• pp.90-101
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• 2009

The purpose of this study was to identify the factors influencing hope in female high school students. The participants were 207 female high school students who were selected from 2 schools located at Province J. The data was collected from September, 2 to 24 in 2009, by self report questionnaires. The data was analyzed using descriptive statistics, t-test, one-way ANOVA, Duncan, Pearson's correlation coefficients and stepwise multiple regression, with the SPSS /WIN 13.0 program. Hope in female high school students differed by economic state and school record. Hope in female high school students positively correlated to task difficulty preference, self-regulatory efficacy, self-confidence, teacher support and peer support. Self-regulatory efficacy, peer support and self-confidence accounted for 34.7% of hope in female high school students. This study showed that self-regulatory efficacy, peer support and self-confidence should be considered in developing a practical nursing intervention program to increase hope in female high school students.

• Corrosion Science and Technology
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• v.2 no.1
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• pp.53-57
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• 2003

The MarM247 based superalloy (8wt.%Cr- 9wt.%Co- 3wt.%Ta- 1.5wt.%Hf- 5.6%wt.Al- 9.5wt.%W- Bal. Ni) specimens were diffusion aluminized by for types of pack cementation methods, and their coating structure and their high temperature oxidation resistance were investigated. The coated specimens treated at 973K in high aluminum concentration pack had a coating layer containing large hafunium rich precipitates, which were originally included in substrate alloy. After the high temperature oxidation test in air containing 30 vol.% $H_2O$ at 1273K ~ 323K, the deep localized corrosion which reached to the substrate were observed along with these hafnium rich precipitates. On the other hand, the coated specimens treated at 1323K using low aluminum concentration pack showed the coating layer without the large hafunium rich precipitates, and after the high temperature oxidation test at 1273K for 1800 ksec, it did not show the deep localized corrosion. The nickel electroplating before the aluminizing forms thick hafnium free area, and its high temperature oxidation resistance were comparable to platinum modified aluminizing coatings at 1273K.