• Proceedings of the KIEE Conference
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• 2008.10a
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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.

• Proceedings of KOSOMES biannual meeting
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• 2009.06a
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• pp.157-158
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• 2009

Phytoplankton plays an important part as indicator and primary producer in marine ecosystem. Therefore, phytoplankton community appeared variously according to marine environment, so the data of nutrients, chlorophyll a, temperature, salinity, and DO were analyzed in seagrass bed of Yeoja Bay. Consequently, the phytoplankton community structures were associated with investigation time and place, and seen difference according to the existence and nonexistence of seagrass bed.

• Communications of the Korean Mathematical Society
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• v.10 no.4
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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 $p \leq q \leq p^* - 1$.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.6
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• pp.2214-2218
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• 2010

Association rule is one of meaning and useful extraction methods from large amounts of data, and furnish useful information to user for data describing a pattern or similarity among attributes in database. Association rule have been studied about existence and nonexistence rule in boolean database. In this paper, we propose an intelligent query system using fuzzy association rule by extraction association rule changing a quantitative attribute data to a nominal attribute value.

• Bulletin of the Korean Mathematical Society
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• v.32 no.2
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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.

• Bulletin of the Korean Mathematical Society
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• v.46 no.5
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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.

• Journal of the Korean Mathematical Society
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• v.47 no.6
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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.

• Journal of Environmental Health Sciences
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• v.16 no.2
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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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• v.7 no.4
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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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• 2000.12a
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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.