• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.6
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• pp.789-795
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• 2010

In order to set up an accurate quality criteria for the Boraginaceae that have been traditionally used for medical purposes and food colorant, and to assess its viability as functional food ingredient, antioxidant tests were conducted on the wild and cultivated plants. Variety of indicators including total contents of phenol, DPPH, SOD-liked effect, hydroxy radical-scavenging effect, lecithin oxidation inhibitory effect, etc were analyzed. Wild and cultivated gromwell's total contents of phenol in their methanol extracts were 0.14% and 0.13%, while they were most active in ethyl acetate extracts and n-hexane extracts, respectively. $IC_{50}$ values of methanol extract of the wild and cultivated plants were 794.41 ${\mu}g$/mL and 971.86 ${\mu}g$/mL, indicating that the wild plant is more responsive (p<0.05) to low concentration. Also the wild and cultivated plants were most active in ethyl acetate fraction and n-hexane extracts when their $IC_{50}$ values were measured by each solvent extracts. SOD-liked effects of both plants were concentration dependent while methanol extracts were more active (p<0.05) in 500 ${\mu}g$/mL than other solvent extracts. Hydroxy radical-scavenging effect of both plants showed less than 50% activity in concentration of 1,000 ${\mu}g$/mL except in chloroform fraction and n-hexane fraction. Lecithin oxidation inhibitory effects of the wild and cultivated plants were active in methanol and solvent extracts of 200~1000 ${\mu}g$/mL. Especially it showed 90% of high inhibitory effect in 1,000 ${\mu}g$/mL of chloroform fraction. Hence, both wild and cultivated Boraginaceae were analyzed to be viable as functional food ingredient.

• Bulletin of the Korean Mathematical Society
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• v.34 no.2
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• pp.185-191
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• 1997

The notions of implicative semigroup and ordered filter were introduced by M. W. Chan and K. pp. Shum [3]. The first is a generalization of implicative semilattice (see W. C. Nemitz [6] and T. S. Blyth [2]) and has a close relation with the implication in mathematical logic and set theoretic difference (see G. Birkhoff [1] and H. B. Curry [4]). For the general development of implicative semilattice theory the ordered filters play an important role, which is shown by W. C. Nemitz [6].

• Electric Engineers Magazine
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• s.274
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• pp.22-28
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• 2005

최근 일부 선진국을 중심으로 대용량 전력제어용 반도체 소자와 제어기술의 발달로 인해 전력전자 반도체 소자인 IGBT(Insulated Gate Bi-polar Transistors) 등을 사용한 승강압형 컨버터 방식으로 동기발전기 계자전류를 제어하는 특이한 모델이 발전기 출력전압을 보다 속응성 있게 제어함은 물론, 신뢰성 있고 안정적으로 제어 할 수 있는 방법으로 등장함에 따라 이에 대한 기술적 연구가 진행되고 있다. 이에따라 본 고에서는 발전기 제어시스템의 개요, 국내외 기술개발 동향과 개발시스템의 구성, 주요기능 그리고 발전소 현장 적용 전에 시스템의 신뢰도 확보를 위해 전동발전기(M-G Set)를 이용한 시스템의 모의시험 결과와 향후 발전기 제어시스템의 발전 전망 등을 9회에 걸쳐 기술한다.

• Electric Engineers Magazine
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• s.273
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• pp.32-36
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• 2005

최근 일부 선진국을 중심으로 대용량 전력제어용 반도체 소자와 제어기술의 발달로 인해 전력전자 반도체 소자인 IGBT(Insulated Gate Bi-polar Transistors) 등을 사용한 승강압형 컨버터 방식으로 동기발전기 계자전류를 제어하는 특이한 모델이 발전기 출력전압을 보다 속응성있게 제어함은 물론, 신뢰성 있고 안정적으로 제어 할 수 있는 방법으로 등장함에 따라 이에 대한 기술적 연구가 진행되고 있다. 이에 따라 본 고에서는 발전기 제어시스템의 개요, 국내외 기술개발 동향과 개발시스템의 구성, 주요기능 그리고 발전소 현장 적용 전에 시스템의 신뢰도 확보를 위해 전동발전기(M-G Set)를 이용한 시스템의 모의시험 결과와 향후 발전기 제어시스템의 발전 전망 등을 그회에 걸쳐 기술한다.

• Proceedings of the KIEE Conference
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• 1993.11a
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• pp.135-138
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• 1993

The Modelling, design and analysis of the steady state and performance characteristic of the constant switching frequency P.W.M controlled LLC and LLCC-type P.R.C are presented continuous conduction mode of operation. A set of characteristic frequency are plotted which design parameters can be obtained.

• East Asian mathematical journal
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• v.23 no.1
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• pp.83-101
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• 2007

In this paper the concept of somewhat pairwise fuzzy continuous functions and somewhat pairwise fuzzy open functions are introduced. Some interesting properties of these functions are investigated besides giving some characterizations of these functions.

• Proceedings of the KIEE Conference
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• 1987.07a
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• pp.820-823
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• 1987

교류전동기의 속도조절과 전력절감에 이용되는 인버터는 그 응용분야에 따라 요구되는 출력특성이 다르게 된다. 본 연구에서는 전동기-발전기 셋트와 반환용 인버터를 이용하여 인버터가 응용되는 환경을 임으로 구현할 수 있는 부하장치를 구성하고, 이때 소모되는 전력을 전원에 반환하여 전력소모를 줄었다.

• Bulletin of the Korean Mathematical Society
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• v.58 no.3
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• pp.573-591
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• 2021

We study the equivariant Gromov-Witten theory of ℙ^r-1 for all r ≥ 2. We prove a polynomiality property in r of the Gromov-Witten classes of ℙ^r-1. Using this polynomiality property, we define a set of polynomial valued classes in $H^*({\bar{M}}_{g,n})$ which generalize the limit of Witten's s-spin classes studied by Pandharipande, Pixton and Zvonkine.

• Journal of Astronomy and Space Sciences
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• v.34 no.3
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• pp.183-197
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• 2017

We present simulations of the optical-band images of high-redshift galaxies utilizing 845 near-ultraviolet (NUV) images of nearby galaxies obtained through the Galaxy Evolution Explorer (GALEX). We compute the concentration (C), asymmetry (A), Gini (G), and $M_{20}$ parameters of the GALEX NUV/Sloan Digital Sky Survey r-band images at z ~ 0 and their artificially redshifted optical images at z = 0.9 and 1.6 in order to quantify the morphology of galaxies at local and high redshifts. The morphological properties of nearby galaxies in the NUV are presented using a combination of morphological parameters, in which early-type galaxies are well separated from late-type galaxies in the $G-M_{20}$, $C-M_{20}$, A-C, and $A-M_{20}$ planes. Based on the distribution of galaxies in the A-C and $G-M_{20}$ planes, we examine the morphological K-correction (i.e., cosmological distance effect and bandshift effect). The cosmological distance effect on the quantitative morphological parameters is found to be significant for early-type galaxies, while late-type galaxies are more greatly affected by the bandshift effect. Knowledge of the morphological K-correction will set the foundation for forthcoming studies on understanding the quantitative assessment of galaxy evolution.

• Solar Energy
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• v.19 no.3
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• pp.43-51
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• 1999

Axisymmetric circular water jet impinges against rectangular heated surface with uniform hear flux and wire-mesh screens are set up in the nozzle-to-heater space to augment heat transfer. In the free jet region to be used them, pressure drop and intensive turbulence flow was brought up. When water jet system is not used wire-mesh screens, maximum heat transfer appears in the stagnation point and the secondary maximum appears X/D=4 but it disappears when they are is used. In the low velocity(Vo<6.0m/s), coarse mesh-screen enhanced heat transfer but fine mesh-screens inpeded heat transfer. In the high velocity(Vo>6m/s), all of them enhanced heat transfer. Average Nusselt number of experimental system to be used wire-mesh screens was promoted $4{\sim}6$times than that of simple water jet system. The stagnation heat transfer of experimental system to be used wire-mesh screens was augmented 6times that of simple water jet system.