• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 Techno-Fair 및 추계학술대회 논문집 전기물성,응용부문
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• pp.95-96
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• 2008

We constructed an on-line PD monitoring system for the 380kV U/G Cable project at the Riyad 9012 substation in Saudi-arabia. The system will be monitoring the termination of the two 380kV XLPE Cables to prevent unexpected failure of the cable insulation. The system had been tested in the laboratory and on-site for detection of various PD signals and reliability of operation. The system distinguish the existence and nonexistence of the partial discharge and then judge the source of partial discharge using automatic PD pattern recognition software.

• 해양환경안전학회:학술대회논문집
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• 해양환경안전학회 2009년도 춘계학술발표회
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• pp.157-158
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• 2009

식물플랑크톤은 해양생태계 내에서 일차 생산자로서 먹이그물의 기초를 이루며 해양환경의 특성을 파악하는데 지표생물로서 중요한 역할을 한다. 그리고 연안에서 식물플랑크톤의 종조성은 해양환경의 시공간 변화에 따라 다양하게 나타난다. 그러므로, 여자만에 생육하는 해초 생태계에서 식물플랑크톤의 변동 특성을 파악하고, 환경요인인 영양염, 클로로필, 수온, 염분과 용존산소를 측정하였다. 그 결과 식물플랑크톤의 군집구조는 조사시기 및 장소와 해초의 유무에 따라 차이를 보였다.

• 대한수학회논문집
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• 제10권4호
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• pp.925-929
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• 1995

Consider the problem $-div($\mid$\bigtriangledown_u$\mid$^{p-2}\bigtriangledown_u) = $\mid$u$\mid$^{p^*-2}u + \lambda$\mid$u$\mid$^{q-2}u$ in B, u = 0 on $\partial B$; where $B \subset R^n$ is a ball, $\lambda < 0, 1 < p < n$ and $p^* = \frac{np}{n-p}$ is the critical Sobolev exponent. For given $\lambda > 0$, we show that there exists $k = k(\lambda) \in N$ such that any radial solutions to this problem have at most k noda curves when $p \leq q \leq p^* - 1$.

• 한국산학기술학회논문지
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• 제11권6호
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• pp.2214-2218
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• 2010

대용량 데이터에서 의미있고 유용한 지식을 추출하는 기법 중의 하나인 연관규칙은 데이터베이스에 존재하는 속성들 사이에 유사성 또는 패턴을 기술하여 사용자에게 데이터에 관한 유용한 정보를 줄 수 있다. 기존에 연구되어 온 연관규칙은 이진(boolean) 데이터베이스에 존재하는 유무에 대한 규칙으로 발견하는 것에 대해서 주로 연구되어왔다. 본 논문에서는 정량적 속성의 데이터를 기호적 속성 값으로 바꾼 후 연관규칙을 추출함으로써, 퍼지개념을 사용한 퍼지 연관규칙을 이용한 지능적 질의 처리 시스템을 제안하고자 한다.

• 대한수학회보
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• 제32권2호
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• pp.211-214
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• 1995

Let M and N be compact Riemannian manifolds and $f : M \to N$ be a smooth map. Following J. Eells, f is exponentially harmonic if it represents a critical point of the exponential energy integral $$ E(f) = \int_{M} exp(\left\$\mid$ df \right\$\mid$^2) dM $$ where $(\left\ df $\mid$\right\$\mid$^2$ is the energy density defined as $\sum_{i=1}^{m} \left\$\mid$ df(e_i) \right\$\mid$^2$, m = dimM, for orthonormal frame $e_i$ of M. The Euler- Lagrange equation of the exponential energy functional E can be written $$ exp(\left\$\mid$ df \right\$\mid$^2)(\tau(f) + df(\nabla\left\$\mid$ df \right\$\mid$^2)) = 0 $$ where $\tau(f)$ is the tension field along f. Hence, if the energy density is constant, every harmonic map is exponentially harmonic and vice versa.

• 대한수학회보
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• 제46권5호
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• pp.823-833
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• 2009

It is well-known that if a convex hyperbolic polygon is constructed as a fundamental domain for a subgroup of the modular group, then its translates by the group elements form a locally finite tessellation and its side-pairing transformations form a system of generators for the group. Such hyperbolically convex polygons can be obtained by using Dirichlet's and Ford's polygon constructions. Another method of obtaining a fundamental domain for subgroups of the modular group is through the use of a right coset decomposition and we call such domains standard fundamental domains. In this paper we give subgroups of the modular group which do not have hyperbolically convex standard fundamental domain containing only inequivalent cusps.

• 대한수학회지
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• 제47권6호
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• pp.1317-1328
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• 2010

In this paper, we study the properties of positive solutions for the reaction-diffusion equation $u_t$ = $\Delta_u+{\int}_\Omega u^pdx-ku^q$ in $\Omega\times(0,T)$ with nonlocal nonlinear boundary condition u (x, t) = ${\int}_{\Omega}f(x,y)u^l(y,t)dy$ $\partial\Omega\times(0,T)$ and nonnegative initial data $u_0$ (x), where p, q, k, l > 0. Some conditions for the existence and nonexistence of global positive solutions are given.

• 한국환경보건학회지
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• 제16권2호
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• pp.127-133
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• 1990

The purpose of the study was to identify the characteristics of the pathogenic microorganism Actinobacillus actinorayceteracomitans. The experiments of this study consist of the decision of existence or nonexistence of Actinobacillus actinorayceterncoraitans in the air of dental clinics, the effect of sugar on the growth of Actinobacillus actinorayceteracoraitans, and the sensitivity of Actinobacillus actinoraycetemcoraitans to Fluorine and antibiotics. The results of the experiments are as follows. 1. Actinobaeillus actinornyceteracornitans did not exist in the air of 4 dental clinics in Seoul 2. The growth of Actinobacillus actinornycetemcornitans in the media containing glucose or sucrose was faster than in the media without these, and glucose was more effective than sucrose. 3. Actinobacillus actinomyceteracoraitans was not susceptible to Fluorine at concentration between 0 ppm and 300 ppm. 4. Order of sensitivity of Actinobacillus actinomycetemcomitans to antobiotics was as follows: Tetracycline > Kanamycin > Ampicillin.

• KIEAE Journal
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• 제7권4호
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• pp.39-44
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• 2007

The purpose of this research is to study security of $CO_2$ exhaust at night in indoor air quality purifying system using plants. For this purpose, two same units for experiment were built, and difference of $CO_2$ exhaust by existence and nonexistence of plantation were measured. To reduce error by entrance of people, automatic measurement system were developed and used. At first, baseline were measured to check standard value, and next, $CO_2$ exhaust by plantation were measured. As a result, in baseline experiment, values of all spaces were steady as 400~500 ppm. When plantation was set-up, value of $CO_2$ at night was measured high as 150 ppm, and maximum value was around 600 ppm. This result is a lot lower than maximum standard of $CO_2$, 1000 ppm.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2000년도 유체기계 연구개발 발표회 논문집
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• pp.219-225
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• 2000

Primary function of a centrifugal compressor volute is to serve the flow from the impeller and diffuser to pipe system. But losses in volutes at off-design lead to poor stage efficiency and reduction of operating range. This is largely caused by the interaction between the impeller and volute flow fields. The magnitude of distortion is increased as the operating point is away from the design point and, as a result, the interaction between the impeller and volute is stronger. The objective of present study is to find the characteristics of tile flow in the diffuser and volute of the centrifugal compressor with rectangular cross-sectional volute. The measurements are carried out in two cases with the existence and nonexistence of the volute casing. The detailed pressure is presented by comparing the experimental results obtained at two cases with each others.