• 대한수학회보
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• 제37권4호
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• pp.743-753
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• 2000

In the space $C_1(X)$ of real-valued continuous functions with $L_1-norm$, every bounded set has a relative Chebyshev center in a finite-dimensional subspace S. Moreover, the set function $F\rightarrowZ_S(F)$ corresponding to F the set of its relative Chebyshev centers, in continuous on the space B[$C_1(X)$(X)] of nonempty bounded subsets of $C_1(X)$ (X) with the Hausdorff metric. In particular, every bounded set has a relative Chebyshev center in the closed convex set S(F) of S and the set function $F\rightarrowZ_S(F)$(F) is continuous on B[$C_1(X)$ (X)] with a condition that the sets S(.) are equal.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 하계종합학술대회 논문집(2)
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• pp.197-200
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• 2001

Novel Enhanced Inductively Coupled Plasma is applied to etch $SiO_2$. Effect of $O_2$ or Ar addition to $C_{4}F_{8}$ gas is monitored by Optical Emission Spectroscopy and Quadrupole Mass Spectrometer. It is fund that Ar or $O_2$ dilution to $C_{4}F_{8}$ increases F emission intensity and decreases $CF_2$ intensity. However, the ac frequency to the Helmholtz coil decreases the F intensity and thus increases $CF_2$/F ratio. By adjusting the ac frequency, the optimum etch rate and PR to $SiO_2$ selectivity can be obtained in E-lCP.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 봄 학술발표회 논문집
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• pp.533-538
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• 2000

In R.C. flat slab system, a brittle punching failure is a very fatal problem. But there is no generally well-defined answer to the problem and there are wide differences in current practical design codes. therefore, in this study, the factors affecting to punching failure mechanism have been studied to find out the punching shear behavior in R.C. flat slabs by comparing other investigations and practical design codes. Therefore, In this study, the factors affecting to punching failure mechanism have been studied to find out the punching shear behavior in R.C. flat slabs by comparing other investigations and practical design codes. The conclusions in this study are summarized as follows; 1) The factors affecting to punching shear are concrete strength ($f_\alpha$), ratio of column side length to slab depth (c/d), ratio of distance from column center to radial contraflexure (l/d), yield strength of steel ($f_y$), flexural reinforcement ratio ($\rho$) and size effects. 2) It is shown that th use of $\surd{f_{ck}}$in applying($f_\alpha$ to punching shear strength estimation may be more sensitive in high concrete strength. 3) The effects of l/d, ($f_y$, size are no clear in the punching failure mechanism, so in the future, it should be investigated with the effects of various composed load.

• 한국양식학회지
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• 제13권4호
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• pp.295-301
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• 2000

1996년 2월 24일 전남 진도에서 채집한 넓은둥근돌김을 엽상체기와 사상체기의 생장, 성숙에 미치는 온도, 광량, 광주기의 영향을 구명하고 둥근돌김과의 생리특성을 비교하고자 수행하였다. 넓은둥근돌김의 엽상체와 사상체는 장.단일하의 5~$25^{\circ}C$에서 생장하며 엽상체는 장일하의 15$^{\circ}C$와 단일하의 10, 15$^{\circ}C$에서 생장과 성숙이 이루어졌고 엽형은 단일하의 1$0^{\circ}C$에서 천연의 조체와 비슷한 폭이 넓은 둥근형으로 되었다. 사상체의 생장은 양광주기하의 2$0^{\circ}C$이상, 40~80${\mu}$mol m$^{-2}$s$^{-1}$의 광량조건에서 빨랐으며, 광주기는 단일조건에 비하여 장일조건이 더 빨랐다. 각포자낭의 형성은 장, 단일하의 15~$25^{\circ}C$에서 나타났으며 각포자낭 형성시기 및 형성률은 단일하의 $25^{\circ}C$에서 빠르고 높게 나타났다. 이상의 결과에서 넓은둥근돌김은 엽상체 및 사상체기에 있어서 둥근돌김과는 다른 생리특성을 갖는 것으로 밝혀졌다. 따라서 넓은둥근돌김은 장일, 고온하의 조건이 5월 이후에도 천연에서 생육 가능성이 높은 것으로 추정되며 하기에도 유아 상태로 여름을 지날 수 있는 가능성이 높은 것으로 시사되었다.

• 센서학회지
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• 제3권2호
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• pp.40-49
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• 1994

$CaF_{2}$ 불화물 고체전해질을 모물질로하는 저온동작용($300^{\circ}C{\sim}$500^{\circ}C) 산소센서를 제조하였다. $CaF_{2}$ 산소센서는 수축률과 SEM사진의 결과를 토대로 $850^{\circ}C$-3hr 동안 열처리 하였다. 디스크형 산소 센서는 기준전극으로 Air($O_{2}:21%$)|Pt를, 전해질로는 $CaF_{2}$, 감지전극으로 Pt를 사용하였으며, 기준전극 내장형 산소센서는 기준전극으로 NiO/Ni (30:70)을 사용하였다. 디스크형 산소센서의 경우 측정온도 $400^{\circ}C$에서 산소농도($0.1 %{\sim}10%$)로 변화시 45mV 정도의 기전력 변화를 보였으며, 기준전극 내장형의 경우는 40mV의 변화를 보였다.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 1993년도 Fifth International Fuzzy Systems Association World Congress 93
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• pp.842-844
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• 1993

We present a F.L.C. (Fuzzy Logic Controller) to control of the oscillation frequency of a V.C.X.O. (Voltage Controled Crystal Oscillator). This F.C.X.O. maintains stable its oscillation frequency inside a range of 1 ppm (one part per millon), with temperature between -55$^{\circ}C$ to＋75$^{\circ}C$.

• ETRI Journal
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• 제36권3호
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• pp.510-513
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• 2014

A Q-band pHEMT image-rejection low-noise amplifier (IR-LNA) is presented using inter-stage tunable resonators. The inter-stage L-C resonators can maximize an image rejection by functioning as inter-stage matching circuits at an operating frequency ($F_{OP}$) and short circuits at an image frequency ($F_{IM}$). In addition, it also brings more wideband image rejection than conventional notch filters. Moreover, tunable varactors in L-C resonators not only compensate for the mismatch of an image frequency induced by the process variation or model error but can also change the image frequency according to a required RF frequency. The implemented pHEMT IR-LNA shows 54.3 dB maximum image rejection ratio (IRR). By changing the varactor bias, the image frequency shifts from 27 GHz to 37 GHz with over 40 dB IRR, a 19.1 dB to 17.6 dB peak gain, and 3.2 dB to 4.3 dB noise figure. To the best of the authors' knowledge, it shows the highest IRR and $F_{IM}/F_{OP}$ of the reported millimeter/quasi-millimeter wave IR-LNAs.

• 한국수산과학회지
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• 제45권5호
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• pp.493-498
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• 2012

We derived biological reference points for Pacific cod Gadus macrocephalus in southeastern Korean waters by applying a yield-per-recruit analysis based on a daily simulation that adopted size-dependent fecundity, growth, and natural mortality functions. This showed that the yield per recruit of Pacific cod can be maximized at an instantaneous rate of fishing mortality (F)=0.37 $yr^{-1}$ under the current regulations, where the minimum catch size ($L_c$)=30 cm in total length (TL). The maximum economic yield was estimated to be attained at $L_c$=35-45 cm TL, if F>1 $yr^{-1}$ but at $L_c$=35-40 cm TL, if F<1 $yr^{-1}$. Despite great uncertainty in the stock assessment, to develop fisheries management plans for the sustainable exploitation of Pacific cod in southeastern Korean waters, it is necessary to estimate F using capture-recapture or other expedient methods.

• 약학회지
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• 제46권2호
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• pp.137-142
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• 2002

Caesalpinia sappan L. has long been commonly used as emmenagogue, analgesic, and a cure for contusion and sprain as well as a remedy for thrombosis in the Oriental medicine. The main constituent of C. sappan is brazilein, which is an antioxidative substance that has a flavonoid structure. In this study, we examined the effect of butanol extract of C. sappan on proliferation and melanogenesis in B16/F10 melanoma cells. After 48h treatment of cells with various concentrations of butanol extract, the cells exhibited a dose-dependent inhibition in their proliferation without apotosis. Therefore, the growth retardation by the extract may be due to the cell arrest, not due to the cell death induced by cytotoxicity. We also estimated total melanin contents as a final product and activity of tyrosinase, a key enzyme, in melanogenesis of B16/F10 melanoma cells. Our result showed that the melanin contents and tyrosinase activity were decreased in butanol extract-treated cells in a dose dependent manner compared to control group. In conclusion, it was observed that butanol extract of C. sappan inhibited melanization of these cells and therefore butanol extract could be developed as skin whitening components of cosmetics.

• 대한수학회논문집
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• 제32권4호
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• pp.827-833
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• 2017

In this paper, we define a set including of all $f_a$ with $a{\in}R$ generalized derivations of R and is denoted by $f_R$. It is proved that (i) the mapping $g:L(R){\rightarrow}f_R$ given by g (a) = f-a for all $a{\in}R$ is a Lie epimorphism with kernel $N_{{\sigma},{\tau}}$ ; (ii) if R is a semiprime ring and ${\sigma}$ is an epimorphism of R, the mapping $h:f_R{\rightarrow}I(R)$ given by $h(f_a)=i_{{\sigma}(-a)}$ is a Lie epimorphism with kernel $l(f_R)$ ; (iii) if $f_R$ is a prime Lie ring and A, B are Lie ideals of R, then $[f_A,f_B]=(0)$ implies that either $f_A=(0)$ or $f_B=(0)$.