• Journal of Korean Institute of Industrial Engineers
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• v.22 no.4
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• pp.619-631
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• 1996

This paper describes an approach for the incorporation of maintenance times into a hierarchical scheduling for a failure prone flexible manufacturing system. The maintenance should not be performed too often because of the resulting reduction of capacity. Most manufacturing systems are large and complex. It is natural to divide the control into a hierarchy consisting of a number of different levels. Each level is characterized by the length of the planning horizon and the kind of data required for the decision making process. The goal of the analysis reported here is to calculate the production requirements while the machines fail and are repaired at random times. The machine failure and preventive maintenance are considered simultaneously.

• Journal of Korea Entertainment Industry Association
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• v.14 no.7
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• pp.589-597
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• 2020

The purpose of this study was to verify the acne care improvement effects of natural cosmetics with distilled bamboo vinegar contents and develop the materials for acne cosmetics. For the research subjects, 20 teenage boys and girls were selected and based on random number table, 10 subjects were assigned in the control group that used natural cosmetics (foam cleanser, toner, facial pack) and 10 subjects were assigned in the experimental group that used natural cosmetics with distilled bamboo vinegar contents (foam cleanser, toner, facial pack). The natural cosmetics was used for 12 weeks, and Mark-·Vu facial analysis system was used to measure the sebum, pore size, and redness before using the natural cosmetics, 6 weeks after using the natural cosmetics, and 12 weeks after using the natural cosmetics. For the collected data, SPSS v. 21.0 statistics package program was used for the analysis, and the results are as follows. First, it is a safe natural cosmetics based on the results of the patch test to confirm the skin safety of the natural cosmetics. Second, homogeneity was secured based on the results of the test of homogeneity for the sebum, pore size, and redness of the control group and experimental group. Third, in the verification of acne skin improvement effects of natural cosmetics with distilled bamboo vinegar content, the experimental group had higher reduction rate of changes in the sebum, pore size, and redness on the forehead and right cheek compared to the control group. Therefore, it was identified that the natural cosmetics with distilled bamboo liquid content is safe for the skin and effective for reducing the sebum, pore size, and redness for acne skin. For this reason, it is anticipated for distilled bamboo vinegar to be used in the cosmetics industry.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.1
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• pp.115-123
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• 2011

Distribution system loss minimization re-configuration is 0-1 planning problem, and the number of combinations requiring searches is extremely large when dealing with typical system scales. For this reason, the application of a genetic algorithm (GA) seems a tractive to solve this problem. Although Genetic algorithms are a type of random number search method, they incorporate a multi-point search feature and are therefore superior to one-point search techniques. The incorporate of GAs for solving large combinational problem has received wide attention. Further, parallel searching can be performed and the optimal solution is more easily reach ed. In this paper, for improving GA convergence characteristics in the distribution system loss minimization re-configuration problem, a chromosome "Limited Life" concept is introduced. Briefly, considering the population homogenization and genetic drift problems, natural selection is achieved by providing this new concept, in addition to natural selection by fitness. This is possible because individuals in a population have an age value. Simulation were carried out using a model system to check this method's validity.

• Journal of Korea Multimedia Society
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• v.12 no.1
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• pp.130-138
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• 2009

As time spent in front of the computer screens increases, an increasing number of people are using natural landscapes or virtual aquariums as their desktop and screen saver that can provide them with mental comfort. A virtual aquarium is constructed by an animation work that creates a variety of fish that freely move in a random virtual underwater environment to analyze their movement. This paper suggests a method that constructs an immersive virtual aquarium, using fluid animation method that expresses changes of shape of fluid in real time and the Smart Fish technology which is capable of an interaction according to the diverse characteristics of virtual fish. The suggested method can be used in a virtual aquarium, aquarium screen saver, virtual fish-raising game, etc., which express diverse undersea environment.

• The Transactions of the Korea Information Processing Society
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• v.5 no.10
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• pp.2713-2724
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• 1998

This paper proposes a new method for the parameter estimation in Markov Random Field(MRF) model of textured color images. The MRF models allow an image region to bel described using a finite number of parameters that characterize spatial interactionsl within and between bands of al color image. An important problem is estimation of the parameters since the randorn field model-based textured color image is the mostly parametric images of natural scenes to verify the validit of the proposed method proves that the method is not affected by the size of the image and shows well-segmented images.

• Journal of Ecology and Environment
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• v.32 no.4
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• pp.229-236
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• 2009

A habitat model was developed to delineate potential habitat of the leopard cat (Prionailurus bengalensis) in a mountainous region of Kangwon Province, Korea. Between 1997 and 2005, 224 leopard cat presence sites were recorded in the province in the Nationwide Survey on Natural Environments. Fifty percent of the sites were used to develop a habitat model, and the remaining sites were used to test the model. Fourteen environmental variables related to topographic features, water resources, vegetation and human disturbance were quantified for 112 of the leopard cat presence sites and an equal number of randomly selected sites. Statistical analyses (e.g., t-tests, and Pearson correlation analysis) showed that elevation, ridges, plains, % water cover, distance to water source, vegetated area, deciduous forest, coniferous forest, and distance to paved road differed significantly (P < 0.01) between presence and random sites. Stepwise logistic regression was used to develop a habitat model. Landform type (e.g., ridges vs. plains) is the major topographic factor affecting leopard cat presence. The species also appears to prefer deciduous forests and areas far from paved roads. The habitat map derived from the model correctly classified 93.75% of data from an independent sample of leopard cat presence sites, and the map at a regional scale showed that the cat's habitats are highly fragmented. Protection and restoration of connectivity of critical habitats should be implemented to preserve the leopard cat in mountainous regions of Korea.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2006.11a
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• pp.105-112
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• 2006

Freak waves in the ocean are recently drawing much attention as a natural disaster to ocean structures and navigating ships as well. Several observation data, among them the Draupner New Year Wave, show the very impressive feature of Freak waves whose wave height is up to three times as high as the significant wave height of surrounding waves, In addition, Freak wave appears as an isolated very high crest in somewhat stationary random waves of same order in their wavelengths. Bearing such characteristics in mind, one notices its extraordinary steepness. This strongly suggests that Freak wave is not long lived but transient nature on the whole. A great number of studies to explain these natures were published from both theoretical and numerical point of view. However it is not sure if they are applicable to actual ocean environment. In this paper, we deal with the results concerning abnormal and/or Freak waves from in-situ ocean wave data and point out several remarks to the problems lain behind the contributions in this context. A physical experiment is described to reinforce the subject discussed from the observation data.

• Smart Structures and Systems
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• v.15 no.5
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• pp.1215-1232
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• 2015

In the present paper, a method for identifying damage in a multi storeyed shear building structure is presented using minimum number of modal parameters of the structure. A damage at any level of the structure may lead to a major failure if the damage is not attended at appropriate time. Hence an early detection of damage is essential. The proposed identification methodology requires experimentally determined sparse modal data of any particular mode as input to detect the location and extent of damage in the structure. Here, the first natural frequency and corresponding partial mode shape values are used as input to the model and results are compared by changing the sensor placement locations at different floors to conclude the best location of sensors for accurate damage identification. Initially experimental data are simulated numerically by solving eigen value problem of the damaged structure with inclusion of random noise on the vibration characteristics. Reliability of the procedure has been demonstrated through a few examples of multi storeyed shear structure with different damage scenarios and various noise levels. Validation of the methodology has also been done using dynamic data obtained through experiment conducted on a laboratory scale steel structure.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1990.10a
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• pp.22-27
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• 1990

Since an eigenvalue problem in structural analysis has been recognized as an important process for the assessment of structural strength, it is usually to be carried out the eigenvalue analysis or buckling analysis of structures when the compression behabiour of the member is dorminant. In general, various variables involved in the eigenvalue problem have also shown their variability. So it is natural to apply the probabilistic analysis into such problem. Since the limit state equation for the eigenvalue analysis or buckling reliability analysis is expressed implicitly in terms of random variables involved, the probabilistic finite element method is combined with the conventional reliability method such as MVFOSM and AFOSM for the determination of probability of failure due to buckling. The accuracy of the results obtained by this method is compared with results from the Monte Carlo simulations. Importance sampling method is specially chosen for overcomming the difficulty in a large simulation number needed for appropriate accurate result. From the results of the case study, it is found that the method developed here has shown good performance for the calculation of probability of buckling failure and could be used for checking the safety of the calculation of probability of buckling failure and could be used for checking the safely of frame structure which might be collapsed by either yielding or buckling.

• Journal of Communications and Networks
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• v.13 no.4
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• pp.319-326
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• 2011

Beamforming techniques have been successfully utilized for traffic channels in order to solve the interference problem. However, their use for control channels has not been sufficiently investigated. In this paper, a (semi-) centralized beamforming strategy that adaptively changes beam patterns and controls the total transmit power of cells is proposed for the performance enhancement of the common channel in hierarchical cell structure (HCS) networks. In addition, some examples of its practical implementation with low complexity are presented for two-tier HCS networks consisting of macro and pico cells. The performance of the proposed scheme has been evaluated through multi-cell system-level simulations under optimistic and pessimistic interference scenarios. The cumulative distribution function of user geometry or channel quality has been used as a performance metric since in the case of common control channel the number of outage users is more important than the sum rate. Simulation results confirm that the proposed scheme provides a significant gain compared to the random beamforming scheme as well as conventional systems that do not use the proposed algorithm. Finally, the proposed scheme can be applied simultaneously to several adjacent macro and pico cells even if it is designed primarily for the pico cell within macro cells.