• Korean Journal of Mathematics
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• v.21 no.4
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• pp.463-471
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• 2013

Let R be a ring with identity 1, $I(R){\neq}\{0\}$ be the set of all nonunit idempotents in R, and M(R) be the set of all primitive idempotents and 0 of R. We say that I(R) is additive if for all e, $f{\in}I(R)$ ($e{\neq}f$), $e+f{\in}I(R)$. In this paper, the following are shown: (1) I(R) is a finite additive set if and only if $M(R){\backslash}\{0\}$ is a complete set of primitive central idempotents, char(R) = 2 and every nonzero idempotent of R can be expressed as a sum of orthogonal primitive idempotents of R; (2) for a regular ring R such that I(R) is a finite additive set, if the multiplicative group of all units of R is abelian (resp. cyclic), then R is a commutative ring (resp. R is a finite direct product of finite field).

• Journal of applied mathematics & informatics
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• v.16 no.1_2
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• pp.221-229
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• 2004

It is known that the parametric boundary equation for the main component in the Mandelbrot set represents a cardioid. We derive an epicy-cloidal boundary equation of the main component in the degree-n bifurcation set by extending the parameter which describes the cardioid in the Mandelbrot set. Computational results as well as some useful properties are presented together with the programming source codes written in Mathematica. Various boundaries are displayed for $2\leqn\leq7$7 and show a good agreement with the theory presented here. The known boundary equation enables us to significantly reduce the construction time for the degree-n bifurcation set.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.37 no.3
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• pp.232-239
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• 2001

For the purpose of providing the basic data on the improved fishing gear and the man power saving, which contribute to enhance fishing efficiency of set net in the coast of Jeju Island, this study analyzed the catch of two fishing place for the past 3 years in order to compare the fishing efficiency between rectngular set net and pound net, which have been used for fishing with being attached to the set net fishing place in coast of Jeiu Island, Thereby the result is as follows ; 1. When using pound net, the total amount of catch during 1997 to 1999 was 2 times more than that of when using rectangular set net. 2. When using Pound net, the catch of squid, mackerel, rabbit fish and Yellow tail during 1997 to 1999 was 1.8 times more than that of when using rectangular set net.. 3. In case of rectangular set net, CPUE marked 10.1㎏ with horse amckerel, 20.5㎏ with squid, 18.0㎏ with rabbit fish and 2.2㎏ with Yellow tail, and in case of pound net, CPUE marked 57.5 ㎏ with horse mackerel, 30.0㎏ with squid, 25.0 with rabbit fish and 4.7㎏ with yellow tail, and on the whole CPUE of poind net marked higher. 4. In case of rectangular set net, the catch ratio for fishing operation marked 64% with horse mackerel, 79% with squid, 39% with rabbit fish and 14% with yellow tail, and in case of pound net, the catch ratio fishing operation marked 18% with horse mackerel, 85% with souid 40% with rabbit fish and 14% with yellow tail, and accordingly it showed the result that the catch ratio for fishing operation was higher with the case of rectangular set net, but higher with the case of pound net.

• Journal of Bio-Environment Control
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• v.24 no.1
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• pp.27-33
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• 2015

High temperature stress in summer season at plastic house is a limiting factor for tomato fruit set and yield. This study was performed to assess the effects of gibberellic acid ($GA_3$) and 2,4-Dichlophenoxy acetic acid (2,4-D) spray on fruit set, yield, and quality of tomato cv. 'Adoration'(Enza Zaden Co., Ltd.) under the plastic house in Hwacheon, 2011. Four concentrations (0-, 5-, 10- and $15mg{\cdot}L^{-1}$) of $GA_3$, and three concentrations (0-, 5- and $10mg{\cdot}L^{-1}$) 2,4-D were sprayed in early flowering of tomato in the plastic house, and fruit set, yield and quality characters were observed. The results showed that spray of $10mg{\cdot}L^{-1}$ $GA_3$ significantly increased the fruit set by 14.2% than unsprayed. The spray of $GA_3$ significantly increased the marketable fruit number, fruit weight, and yield. The spray of 2,4-D on blossoms significantly affected the fruit set percentage, fruit weight, marketable fruit weight and yield, and the highest fruit set observed as 62.5% in combined spray of $GA_3$ and 2,4-D at each $5mg{\cdot}L^{-1}$. Fruit size and total soluble solids significantly varied with the concentrations of $GA_3$ sprayed. The result indicates that the spray of $10mg{\cdot}L^{-1}$ $GA_3$ and $5mg{\cdot}L^{-1}$ 2,4-D can be more economic and effective to increase the fruit set, and yield in tomato under high temperature condition in plastic house.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.782-786
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• 2003

It requires protection technologies to permit consumer to store a digital broadcasting content and at the same time to protect the intellectual property from illegal action. There is content encryption as one of protection technologies. In this paper, we proposed a protection scheme for digital broadcasting content that broadcasting server. Multiplexes the encryption key into MPEG-2 TS(transport stream) to be able to encrypt received TS at set top box. The proposed method is to modify PMT(program map table) for the information related encryption key and to multiplex key as TS packets. After then the encryption key is extracted from TS stream which is encrypted in set top box.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.392-395
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• 2017

본 연구에서는 일 증발접시 증발량 산정을 위한 딥러닝 (deep learning) 모형의 적용성을 평가하였다. 본 연구에서 적용된 딥러닝 모형은 deep belief network (DBN) 기반 deep neural network (DNN) (DBN-DNN) 모형이다. 모형 적용성 평가를 위하여 부산 관측소에서 측정된 기상자료를 활용하였으며, 증발량과의 상관성이 높은 기상변수들 (일사량, 일조시간, 평균지상온도, 최대기온)의 조합을 고려하여 입력변수집합 (Set 1, Set 2, Set 3)별 모형을 구축하였다. DBN-DNN 모형의 성능은 통계학적 모형성능 평가지표 (coefficient of efficiency, CE; coefficient of determination, $r^2$; root mean square error, RMSE; mean absolute error, MAE)를 이용하여 평가되었으며, 기존의 두가지 형태의 ANN (artificial neural network), 즉 모형학습 시 SGD (stochastic gradient descent) 및 GD (gradient descent)를 각각 적용한 ANN-SGD 및 ANN-GD 모형과 비교하였다. 효과적인 모형학습을 위하여 각 모형의 초매개변수들은 GA (genetic algorithm)를 이용하여 최적화하였다. 그 결과, Set 1에 대하여 ANN-GD1 모형, Set 2에 대하여 DBN-DNN2 모형, Set 3에 대하여 DBN-DNN3 모형이 가장 우수한 모형 성능을 나타내는 것으로 분석되었다. 비록 비교 모형들 사이의 모형성능이 큰 차이를 보이지는 않았으나, 모든 입력집합에 대하여 DBN-DNN3, DBN-DNN2, ANN-SGD3 순으로 모형 효율성이 우수한 것으로 나타났다.

• Journal of the Chungcheong Mathematical Society
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• v.28 no.4
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• pp.635-645
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• 2015

We will show the general solution of the functional equation $$\begin{eqnarray}f(x+ay)+f(x-ay)+2(a^2-1)f(x)\\=a^2f(x+y)+a^2f(x-y)+2a^2(a^2-1)f(y)\end{eqnarray}$$ and investigate the Hyers-Ulam stability of the quartic set-valued functional equation.

• Journal of the Chungcheong Mathematical Society
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• v.16 no.1
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• pp.7-14
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• 2003

Let $P_c(z)=z^n+c$ be a complex polynomial with an integer $n{\geq}2$. We derive a criterion that the critical orbit of $P_c$ escapes to infinity and investigate its applications to the degree-n bifurcation set. The intersection of the degree-n bifurcation set with the real line as well as with a typical symmetric axis is explicitly written as a function of n. A well-defined escape-time algorithm is also included for the improved construction of the degree-n bifurcation set.

• Journal of the Chungcheong Mathematical Society
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• v.9 no.1
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• pp.107-113
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• 1996

For continuous maps f of the circle to itself, we show that (1) the set of ${\omega}$-limit points is contained in the set of nonwandering points of $f^n$ for all $n{\geq}1$. (2) if the set of turning points of f is finite, then the set of accumulation points of non wandering set is contained in the set of non wandering points of $f^n$ for all $n{\geq}1$.

• The Pure and Applied Mathematics
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• v.23 no.4
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• pp.377-383
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• 2016

The set of priors in the representation of coherent risk measure is expressed in terms of quantile function and increasing concave function. We show that the set of prior, $\mathcal{Q}_c$ in (1.2) is equal to the set of $\mathcal{Q}_m$ in (1.6), as maximal representing set $\mathcal{Q}_{max}$ defined in (1.7).