• 대한수학회논문집
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• 제20권3호
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• pp.427-436
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• 2005

Let (R, m) be a 2-dimensional regular local ring with algebraically closed residue field R/m. Let K be the quotient field of R and v be a prime divisor of R, i.e., a valuation of K which is birationally dominating R and residually transcendental over R. Zariski showed that there are finitely many simple v-ideals $m=P_0\;{\supset}\;P_1\;{\supset}\;{\cdotS}\;{\supset}\;P_t=P$ and all the other v-ideals are uniquely factored into a product of those simple ones. It then was also shown by Lipman that the predecessor of the smallest simple v-ideal P is either simple (P is free) or the product of two simple v-ideals (P is satellite), that the sequence of v-ideals between the maximal ideal and the smallest simple v-ideal P is saturated, and that the v-value of the maximal ideal is the m-adic order of P. Let m = (x, y) and denote the v-value difference |v(x) - v(y)| by $n_v$. In this paper, if the m-adic order of P is 2, we show that $O(P_i)\;=\;1\;for\;1\;{\leq}\;i\; {\leq}\;{\lceil}\;{\frac{b+1}{2}}{\rceil}\;and\;O(P_i)\;=2\;for\;{\lceil}\;\frac{b+3}{2}\rceil\;{\leq}\;i\;\leq\;t,\;where\;b=n_v$. We also show that $n_w\;=\;n_v$ when w is the prime divisor associated to a simple v-ideal $Q\;{\supset}\;P$ of order 2 and that w(R) = v(R) as well.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2015년도 제46회 하계학술대회
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• pp.1173-1174
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• 2015

내연 발전기(50 MW, 13.8 kV) 출력단자에서 차단기까지 연결된 13.8 kV XLPE(cross-linked polyethylene) 케이블에서 운전중에 절연파괴로 인해 지락이 발생하였다. XLPE 케이블의 건전성을 확인하기 위해 절연저항과 절연진단 시험을 수행하였다. 교류전압을 1~10 kV까지 증가하면서 XLPE 케이블의 유전정접 측정결과 A상과 C상은 0.1%로 일정하게 측정되었다. 반면에 B상의 유전정접은 1 kV에서 0.54%, 2 kV에서 0.68%, 3 kV에서 0.82%, 4 kV에서 1.12%로 증가하였다. 그리고 교류전압을 약 4.3 kV 인가 중에 진단장비가 차단되었다.

• 한국컴퓨터정보학회논문지
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• 제20권1호
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• pp.227-235
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• 2015

본 논문은 NP-완전으로 알려진 최대 클릭의 정확한 해를 선형시간으로 찾는 알고리즘을 제안하였다. 먼저, 주어진 그래프 G=(V,E)에서 최대 차수 ${\Delta}(G)$ 정점 $v_i$를 클릭의 대표 정점으로 결정한다. $v_i$ 인접 정점 $N_G(v_i)$에서 ${\Delta}(G)$ 정점 $v_j$를 선택하여 $N_G(v_i){\cap}N_G(v_j)$를 후보 클릭 w와 $v_k$로 결정한다. $d_G(v_k)$ 내림차순으로 $w=w{\cap}N_G(v_k)$를 얻는다. 마지막으로, $G{\backslash}w$그래프에서 동일한 절차를 수행하여 얻은 클릭이 기존에 얻은 클릭과 동일하거나 크면 이 클릭을 선정하는 검증과정을 거쳤다. 이와 같은 방법으로 독립된 다수의 클릭도 얻을 수 있는 장점이 있다. 제안된 알고리즘을 다양한 정규와 비정규 그래프에 적용한 결과 모든 그래프에 대해 선형시간 O(n)으로 정확한 해를 구하였다.

• 전기학회논문지
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• 제58권4호
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• pp.788-794
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• 2009

To assess the condition of stator insulation, nondestructive tests were performed on twenty five coil groups and twenty six motors. The stator windings has nominal ratings of 6.6kV and are classified into five coil groups ;one group with healthy insulation and four groups with four different types of artificial defects. After completing nondestructive tests, the AC voltage applied to the stator windings was gradually increasing until insulation failure in order to obtain the breakdown voltage. No.1, No.2 and No.6 of 6.6kV motors failed near rated voltage of 14kV, 8.7kV and 14kV, respectively. The breakdown voltage of three motors was lower that expected for good quality coils(14.2kV) in 6.6kV motors. No.3 and No.6 of 4.16kV motors failed near rated voltage of 5.6kV and 4.2kV, respectively. Almost all of failures were located in a line-end coil at the exit from the core slot. The breakdown voltages and the types of defects showed strong relation to the stator insulation tests such as in the case of AC current, dissipation factor(tan${\delta}$) and partial discharge magnitude.

• 한국방사선학회논문지
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• 제14권4호
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• pp.353-360
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• 2020

본 연구는 CBCT 장비의 표준 노출 조건(80 kV, 7 mA)을 기준으로 관전압과 관전류를 낮추어 촬영하면서 표준 노출 조건의 물리적 화질 요소값을 유지할 수 있는 노출 조건의 제시를 목표로 두고자한다. 영상의 물리적 화질 요소값의 측정을 위해 변조전달함수(MTF)가 분석되었고 선량 측정을 위해 선량-면적 곱(DAP)을 이용하였다. 관전압(80, 78, 76 kV)과 관전류(7, 6, 5, 4, 3 mA)의 15가지 조합의 노출 조건에서 Sedent ex IQ 팬텀 (Leeds Test Objects Ltd., Boroughbridge, UK)의 CBCT 영상을 얻었고 MTF 10이 각 조건에서 계산 되었다. 표준 노출 조건과 비교시 80 kV-6 mA, 80 kV-5 mA 노출 조건은 MTF 10에 있어 유의한 차이를 보이지 않았기에 본 연구에서 사용된 CBCT 장비의 경우, 80 kV-5 mA로 낮춘 노출 조건에서 물리적 화질요소값을 유지하면서 선량을 감소시킬 수 있는 것으로 판단되어진다.

• 식물분류학회지
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• 제48권3호
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• pp.206-217
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• 2018

The nucleotide sequences of the chloroplast rbcL, matK, and psbA-trnH and nuclear internal transcribed spacer (ITS) regions were determined from all species of Viburnum in Korea with multiple accessions to reconstruct the phylogeny and to evaluate the utility of the DNA sequences as DNA barcodes. The results of phylogenetic analyses of the cpDNA and ITS data are consistent with the findings of previous studies of Viburnum. Four morphologically closely related species, V. dilatatum, V. erosum, V. japonicum, and V. wrightii, were included in a strongly supported sister clade of V. koreanum and V. opulus. Viburnum odoratissimum is suggested to be sister to the V. dilatatum/V. koreanum clade in the cpDNA data, while V. odoratissimum is a sister to V. furcatum in the ITS data. Viburnum burejaeticum and V. carlesii are strongly supported as monophyletic. Our analyses of DNA barcode regions from multiple accessions of the species of Viburnum in Korea confirm that six out of ten species in Korea can be discriminated at the species level. The V. dilatatum complex can be separated from the remaining species according to molecular data, but the resolution power to differentiate a species within the complex is weak. This study suggests that regional DNA barcodes are useful for molecular species identification in the case of Viburnum when flowering or fruiting materials are not available.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 C
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• pp.831-833
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• 1998

It is getting more difficult to construct new transmission lines, due to the increase of people's demand resulting from the change of social environment and people's consciousness. In order to solve these complicated conditions. we developed a computer system to support the route selecting and surveying of a transmission line. This paper introdouces the methodology for route selecting, designing, surveying of a transmission line and tower designing process using a computer system.

• 충청수학회지
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• 제9권1호
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• pp.77-87
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• 1996

For any map $v:X{\rightarrow}Y$, the generalized Gottlieb set $G({\Sigma}A;X,v,Y)$ with respect to v is a subgroup of $[{\Sigma}A,Y]$. If $v:X{\rightarrow}Y$ has a left homotopy inverse $u:X{\rightarrow}Y$, then for any $f{\in}G({\Sigma}A;X,v,Y)$, $g{\in}G({\Sigma}A;X,u,Y)$, the function spaces $L({\Sigma}A,X;uf)$ and $L({\Sigma}A,X;g)$ have the same homotopy type.

• Journal of Microbiology and Biotechnology
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• 제16권7호
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• pp.1120-1124
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• 2006

Supplementation with rice oil and its major components (oleic acid and linoleic acid) was found to have a significant influence on cephalosporin C (CPC) production and cell growth by A. chrysogenum M35 in shake flask cultures. Five percent (v/v) rice oil had the most robust effect and 5% (v/v) oleic acid was the second most efficient on cell growth, whereas 3% (v/v) linoleic acid was found to be optimal for CPC production. Rice oil, oleic acid, and linoleic acid also significantly improved the rates of glucose consumption. When glucose was almost consumed, CPC production was initiated and, on the addition of rice oil, lipase activity increased steadily to 1.56 U/ml for 4 days. These results suggest that rice oil and fatty acids are used as carbon source to produce CPC by A. chrysogenum M35. Moreover, a mixture, composed of 40% (v/v) oleic acid and 60% (v/v) linoleic acid, had the strongest stimulatory effect on CPC production, due to a synergistic effect of the two fatty acids. Consequently, the maximum CPC titer (7.44 g/l) was improved about 4.5-fold.

• 대한화학회지
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• 제30권1호
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• pp.19-26
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• 1986

공기산화와 수증기 산화법에 의하여 Ti$O_{2-x}$박막을 만들었고, 알곤 기체속에서 $TiO_2$단결정을 환원하였다. Ti$O_{2x}박막의 전극 특성은 환원된 단결정 rutile의 특성과 거의 같았다. 산소가 용해된 전해질용액에서 측정된 Ti$O_{2-x}$전극들의 전류-전압 곡선으로 부터 음극전류의 peak는 -0.8V ~ -1.0V에서 나타났으며, 영볼트 근처의 Ti$O_{2-x}$전극들의 음극전류는 공기로 포화된 용액에서 보다 질소로 포화된 용액에서 더 크게 나타났다. 시간에 따르는 전류 (i)의 변화는 $i_0e^{-kt}$식에 의존하였고 이때의 속도상수(k)는 $k_0{[H^+]}^nexp(A{\eta}+\frac{E_a}{RT})$로 나타낼 수 있었다. 여기서 활성화에너지 Ea는 0.035~0.145V의 과전압에서는 4.6~4.8kcal/mole, 0.2~0.5V의 과전압에서는 1.6kcal/mole이고, 위식중의 n과 A는 0.035~0.145V에서 0.1과, 5.4~5.6/V, 0.2~0.5V에서는 0.04와 1.3/V이었다. 산소의 환원반응은 전체적으로 비가역 반응임을 알았다.