• 전기학회논문지
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• 제57권5호
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• pp.748-754
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• 2008

The general capacitor placement problem is a combinatorial optimization problem having an objective function composed of power losses and capacitor installation costs subject to bus voltage constraints. In this paper, a global optimization technique, which employing the chaos search algorithm, is applied to solve optimal capacitor placement problem with reducing computational effort and enhancing global optimality of the solution. Chaos method in optimization problem searches the global optimal solution on the regularity of chaotic motions and easily escapes from local or near optimal solution than stochastic optimization algorithms. The chaos optimization method is tested on 9 buses and 69 buses system to illustrate the effectiveness of the proposed method.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 A
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• pp.403-405
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• 2003

In this paper, we applied a chaos search method for feeder reconfiguration problem in unbalanced distribution system. Chaos method, in optimization problem, searches the global optimal solution on the regularity of chaotic motions and more easily escapes from local or near optimal solution than stochastic optimization algorithms. The chaos search method applied to the IEEE 13 unbalanced test feeder systems, and the test results indicate that it is able to determine appropriate switching options for global optimum configuration.

• 생명과학회지
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• 제17권8호통권88호
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• pp.1068-1074
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• 2007

파브알부민(pa π albumin)은 망막의 다양한 세포타입에서 분포하고 있다. 본 연구팀은 이전연구에서 박쥐 망막의 내핵층에서의 파브알부민의 분포를 보고하였다. 현재 연구에서 본 연구팀은 한국관박쥐 (Rhinolophus ferrumequinum) 망막의 신경절세포층에 존재하는 파브알부민을 함유하는 신경세포를 규명하였고, 이들 세포의 분포양상을 조사하였다. 실험 결과,파브알부민의 면역반응성은 신경절세포층의 다수 세포에서 발견되었으며, 이들 세포는 주로 중간형 이상 크기의 세포체를 가지고 있었다. 조사된 세포체의 직경은 12.35 - 19.12 ${\mu}m$ 의 범위를 가지며 (n=166), 신경섬유층의 섬유 역시 염색되는 것으로 보아, 파브알부민을 함유하는 신경절세포는 대부분이 중간형이상 크기의 신경절세포임을 뒷받침하고 있다. NND (nearest neighbor distance) 분석을 통해서 본, 평균 NND는 59.57 에서 62.45 ${\mu}m$ 로 나타났으며, 평균 RI (regularity index) 는 2.95 ${\pm}$ 0.3 (mean${\pm}$s.d., n=4) 으로 계산되었다. 이를 종합해보면, 파브알부민은 한국관박쥐 망막의 신경절세포층에서 중간형이상 크기의 신경절세포에서 주로 발현하고 있으며, 이들은 규칙적인 배열을 가진 채 잘 조직화된 분포양상을 보여주고 있음을 알 수 있었다. 이러한 결과들은, 아직까지 명확하게 규명되어 있지 못한 박쥐의 시각에 대한 이해에 중요하게 적용될 수 있을 것이라고 사료된다.

• Steel and Composite Structures
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• 제44권5호
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• pp.619-632
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• 2022

There are numerous structural details (Longitudinal beam, web plate, U-ribs and I-ribs) in the top and bottom plates of steel box girders, which have significant influences on the longitudinal stress (normal stress) distribution. Clarifying the influence of these structural details on the normal stress distribution is important. In this paper, the ultra-wide steel box girder with large cantilevers of the Jinhai Bridge in China, which is the widest cable-stayed bridge in the world, has been analyzed. A 1:4.5 scale laboratory model of the steel box girder has been manufactured, and the influence of structural details on the normal stress distribution in the top and bottom plates for four different load cases has been analyzed in detail. Furthermore, a three-dimensional finite element model has been established to further investigate the influence regularity of structural details on the normal stress. The experimental and finite element analysis (FEA) results have shown that different structural details of the top and bottom plates have varying effects on the normal stress distribution. Notably, the U-ribs and I-ribs of the top and bottom plates introduce periodicity to the normal stress distribution. The period of the influence of U-ribs on the normal stress distribution is the sum of the single U-rib width and the U-rib spacing, and that of the influence of I-ribs on the normal stress distribution is equal to the spacing of the I-ribs. Furthermore, the same structural details but located at different positions, will have a different effect on the normal stress distribution.

• 대한영양사협회학술지
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• 제10권3호
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• pp.364-374
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• 2004

This Study was carried out to investigate dietary life and recognition of diet related factors in elemantary, middle and high school students. This study was surveyed by questionnaires and data were analyzed by SPSS program. Comparative analysis was conducted according to three school student groups(elementary childrens, middle school students, high school students). The subjects were 1,886 school students(female 893, male 959) of 51 schools in nationalwide region. The Distribution of subjects was elementary school childrens 544, middle school students 661 and high school students 681. The results are summarized as follows. Only Sixty percent of the subjects had breakfast regularly. About one forth of the subjects had the habit of skipping breakfast or eating 2-3 times per week. Pricipal reasons of skipping breakfast were 'busy'(50.7%) and 'not delicious or poor appetite'(31.0%). Regularity of having breakfast and reasions of skipping breakfast were significant differences according to school student groups(p<0.001 respectively). About half of the subjects didn't have sufficient amounts in breakfast. Most subjects(92.1%) had lunch regularly by virtue of school lunch service. One forth of the subjects had dinner irregularly. Pricipal reasons of skipping dinner were 'not delicious'(41.7%), 'busy'(15.1%) and 'weight loss'(14.3%). Regularity of having dinner and reasons of skipping dinner were significant differences according to school student groups(p<0.01, p<0.001 respectively). The most delicious meal was dinner in 56.7% of the subjects and lunch in 37.1% of the subjects. There was significant difference in recognition of most delicious meal according to school student groups(p<0.001). Only ten percent of the subjects thought that nutrition education was not needed. Diettitian was recognized as nutrition educator in sixty percent of the subjects. Only 5 percent of the subject recognized teacher as nutrition educator. There were not significant differences in most delicious meal and nutrition educator according to operation type of school lunch service. The findings suggested continuous attention and guidance for healthy dietary life and necessity of nutrition education for both school students and their parents.

• 대한의용생체공학회:의공학회지
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• 제19권6호
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• pp.585-593
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• 1998

퓨리에 자기공명영상 기법의 경우 촬영시간 단축 및 적절한 신호대잡음비 유지를 위해 phase-encoded 신호의 개수를 감소시키는 경우가 종종 있다. 그러나, 이는 재구성된 영상에 번짐과 물결무늬 형태의 truncation artifact를 초래한다. 본 논문에서는 이러한 truncation artifact를 감소시키기 위해 Bayesian 방법에 근거한 새로운 정칙화기법을 제안한다. Truncation artifact는 phase 방향으로만 형성되므로 종전의 상호 대칭형태의 주변화소를 고려한 piecewise smoothness 사전정보를 사용할 경우 read 방향으로의 미세한 영상정보가 유실되기 쉽다. 따라서, 본 연구에서는 종전의 단순대칭형 보다 개선된 형태로서 자기공명영상의 공간정보를 포착할 수 있는 정교한 사전정보의 형태를 제안한다. 본 연구진의 실험결과 새롭게 제안된 방법으로 적용할 경우 truncation artifact가 감소될 뿐 아니라 종전의 미세정보유실 현상이 감소됨으로써 tissue regularity와 경계가 한층 더 향상됨을 확인할 수 있었다.

• 한국식품영양학회지
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• 제19권4호
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• pp.502-514
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• 2006

This Study was carried out to find out regional differences about dietary life and factors associated with meal of school children and adolescents between urban and rural area. Forty students from each of the nationwide 51 schools of three different levels(elementary, middle and high school) were surveyed by self-developed questionnaires. Total of 1,886 questionnaires (1,243 from urban and 681 from rural) were collected and distribution of subjects was 544 from elementary school, 661 from middle school, and 681 from high school. The results were summarized as follows. BMI and degree of satisfaction on body weight of elementary and middle school subjects were not significantly different between urban and rural area. But there were significant regional differences in $BMI(urban\;21.2{\pm}3.0,\;rural\;20.5{\pm}2.8,\;p<0.05)$ and degree of satisfaction on body weight of high school subjects(p<0.001). Elementary(p<0.01) and middle school(p<0.05) subjects in urban area had exercised more frequently than those in rural area. Regularity of having breakfast was not significantly different between urban and rural area at each of three different levels of school. Most subjects(urban 92.2%, rural 92.1%) had lunch regularly by virtue of school lunch service. Regularity of having dinner of elementary(p<0.01) and high school subjects (p<0.01) was significantly different between urban and rural area. Reason for skipping dinner of high school subjects was significantly different between urban and rural area (p<0.05). The most delicious meal was dinner for 51.8% of the urban high school subjects and lunch for 51.7% of the rural subjects. Only one third had intention of participating in school breakfast program regardless of region and levels of school. The findings suggested that nutrition education programs for school children and adolescents include different strategy according to region and levels of schools.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권4호
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• pp.1866-1883
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• 2019

As the youngest branch of information hiding, network covert timing channels conceal the existence of secret messages by manipulating the timing information of the overt traffic. The popular model-based framework for constructing covert timing channels always utilizes cumulative distribution function (CDF) of the inter-packet delays (IPDs) to modulate secret messages, whereas discards high-order statistics of the IPDs completely. The consequence is the vulnerability to high-order statistical tests, e.g., entropy test. In this study, a rich security model of covert timing channels is established based on IPD chains, which can be used to measure the distortion of multi-order timing statistics of a covert timing channel. To achieve rich security, we propose two types of covert timing channels based on nested lattices. The CDF of the IPDs is used to construct dot-lattice and interval-lattice for quantization, which can ensure the cell density of the lattice consistent with the joint distribution of the IPDs. Furthermore, compensative quantization and guard band strategy are employed to eliminate the regularity and enhance the robustness, respectively. Experimental results on real traffic show that the proposed schemes are rich-secure, and robust to channel interference, whereas some state-of-the-art covert timing channels cannot evade detection under the rich security model.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 추계종합학술대회 논문집(4)
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• pp.9-12
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• 2000

This paper proposes an improved image illumination estimation method based on the conventional color constancy algorithm. The most important process of color constancy algorithm is the estimation of the spectral distributions of illuminant of an input image. To estimate of the spectral distributions of illuminant of an input image, we use the brightest pixel values and the values of surface reflectance of an input image using a principal component analysis of the given munsell chips. We estimate a CIE tristimulus values of an input image using the estimated .spectral distribution of illuminant and recover an image by scaling it regularity. From the experimental results, the proposed method was effective in estimating the image illumination

• Journal of Advanced Marine Engineering and Technology
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• 제30권1호
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• pp.140-149
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• 2006

Characteristics of a laminar diffusion flame placed near wall in microgravity have been numerically analyzed in a two-dimension. The fuel for the flame is $C_2H_4$. The flame is initiated by imposing a high temperature ignition source. The flow field, temperature field, and flame shape in microgravity diffusion flame are detailed. Especially, effects of surrounding air velocity and fuel injection velocity on the microgravity diffusion flame have been discussed accounting for standoff distance. And, the effect of curvature rate has been also studied. The results showed that velocities in a diffusion flame were overshoot because of volumetric expansion and distribution of temperature showed regularity by free-buoyancy This means that the diffusion flame in microgravity is very stable, while the flame in normal gravity is not regular and unstable due to buoyancy. Standoff distance decreases with increase in surrounding air velocity and with decrease in fuel injection velocity. With increasing curvature rate, the position of reaction rate moves away the wall.