• Progress in Medical Physics
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• v.7 no.2
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• pp.79-90
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• 1996

In this paper, we present an automatic threshold decision method to detect the contour of the a 2-D echocarodiogram by using the Bayes estimator for the boundary-like region. The boundary-like region is constructed from the conduction coefficient of the heat anisotro-pic diffusion method which enforces the blurred image during the preprocessing step. For the boundary-like region, we used the Bayes estimator to select an optimal threshold level. From this threshold value, the contour of the echocardigrams can be detected automatically Finally by overlapping the estimated contour to the original echocardiogram, we can obtain the contour enforced ultrasound echocardiogram.

• The Korean Journal of Applied Statistics
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• v.17 no.2
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• pp.239-252
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• 2004

It is known that the domestic and the U.S. stock prices tend to move together as those markets are closely interrelated. In this study, cointegration and causal relationships among the four stock price indexes of KOSPI, KOSDAQ, DOWJONES and NASDAQ are carefully investigated for the period of declining stock prices in the long run. When all indexes move in a similar fashion, cointegration does not exist and the causal linkages between the domestic and the U.S. stock prices appear relatively complex. On the other hand, when the domestic and the V.S. stock prices move in a different manner, cointegration exists and the causal relationships appear relatively simple. NASDAQ is apparently found to lead the domestic stock market in both periods, which is consistent with the actual market situation when the If industry is under recession.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.2
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• pp.184-191
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• 1993

Continuous-time integrated filters, implemented in MOS VLSI technology, have been receiving considerable attention. In this paper, a continuous-time fifth order elliptic low-pass MOSFET-C filter has been designed with a cutoff frequency 3,400Hz. First an active RC filter is designed using cascade method which each block can be tunable. And then the resistors of an active RC network are replaced by a linear resistor using NMOS depletion transistors operated in the triode region. This continuous-time MOSFET filter have simpler structure than switched-capacitor filter, so reduce the chip area. The designed MOSFET-C filter characteristics are simulated by PSPICE program.

• Aerospace Engineering and Technology
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• v.5 no.2
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• pp.195-204
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• 2006

A linear acoustic analysis has been performed to elucidate damping characteristics of acoustic cavities in a liquid rocket combustor. Results have shown that resonant frequencies of acoustic cavity obtained by classical theoretic approach and by the present linear analysis are somewhat different with each other. This difference is attributed to the limitation of the simplified classical theory. To quantify the damping characteristics, acoustic impedance has been introduced and resultant absorption coefficient and conductance have been evaluated. Satisfactory agreement has been achieved with previous experiment. Finally the design procedure for an optimal tuning of acoustic cavity has been established.

• Proceedings of the KIEE Conference
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• 2009.04b
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• pp.32-34
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• 2009

The field oriented control of induction motors is widely used in high performance applications. However, detuning caused by parameter disturbance still limits the performance of these drives. In order to accomplish variable speed operation, conventional PI-like controllers are commonly used. These controllers provide limited good Performance over a wide range of operation, even under ideal field oriented conditions. This paper is proposed model reference adaptive fuzzy control(MFC) and artificial neural network(ANN) based on the vector controlled induction motor drive system. Also, this paper is proposed control of speed and current using fuzzy adaption mechanism(FAM), MFC and estimation of speed using ANN. The proposed control algorithm is applied to induction motor drive system using FAM, MFC and ANN controller. Also, this paper is proposed the analysis results to verify the effectiveness of this controller.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1453-1455
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• 2005

This paper presents self tuning PI controller of IPMSM drive using neural network. Self tuning PI controller is developed to minimize overshoot, rise time and settling time following sudden parameter changes such as speed, load torque and inertia. Also, this paper is proposed speed control of IPMSM using neural network and estimation of speed using artificial neural network(ANN) controller. The results on a speed controller of IPMSM are presented to show the effectiveness of the proposed gain tuner. And this controller is better than the fixed gains one in terms of robustness, even under great variations of operating conditions and load disturbance.

• The Journal of the Korea Contents Association
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• v.20 no.11
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• pp.204-215
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• 2020

We analyze changes of consumption behavior for bundle services for the latest three years focusing on comparing the detailed service types and service providers to understand competition structure in the market. Our major findings and implications are as follows. First, the mobile telecommunication service is certainly deemed to be a major selection criteria for bundling service provider, therefore the leading company in the mobile telecommunication has become more significant market power. Second, IPTV has an important influence for slection of bundling service provider, lately in some cases, rather than broadband Internet. Third, the individual services affecting the selection of bundling service providers clearly showed differentiation among three operators as a mobile telecommunication service of SK Group, a broadband Internet of KT, and an IPTV of LGU+. In addition, the importance of individual services in securing subscribers has been increased as the preference factors to switch a service provider were synchronized with the decision of major bundling service provider. Finally, although it is difficult to find customers' lock-In due to the latest change of their intentions to switch a provider, we find it is continuously necessary to monitor customers' lock-in as there are more long-term customers with re-contracts. Our results provide the policy implications based on the change of competition structure and usage behavior in the bundle market which is not evaluated the competiton situation.

• Korean Journal of Microbiology
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• v.49 no.1
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• pp.1-7
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• 2013

During meiosis, genetic recombinants are formed by homologous recombination accompanying with the programmed double-strand breaks (DSBs) and strand exchanges between homologous chromosomes. The mechanism is generated by recombination intermediates such as single-end invasions (SEIs) and double-Holliday junctions (dHJs), and followed by crossover (CO) or non-crossover (NCO) products. Our study was focused on the analysis of meiotic recombination intermediates (DSBs, SEIs, and dHJs) and final recombination products (CO and NCO). We identified these meiotic recombination intermediates using DNA physical analysis under HIS4LEU2 "hot spot" system in budding yeast, Saccharomyces cerevisiae. For DNA physical analysis, when the hot spot locus is recognized by restriction enzyme from synchronous meiotic cells, the fragmented DNA that are forming recombination intermediates can be detected and quantified through Southern hybridization analysis. Our study suggests that this system can analyze the structural change of recombination intermediates during DSB-SEI transition, double-Holiday junctions and crossover/non-crossover products in meiosis.

• The Journal of the Korea Contents Association
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• v.15 no.9
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• pp.395-402
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• 2015

when the radiation therapy of chest and abdomen, evaluation of the tumor motion and the data was used to minimize damage to normal tissues by separating the tumor and normal tissue and maximize tumor therapeutic effect. Lung and liver cancer each 20 patients based on the 50% top phase using 4D-CT simulation and Light speed-16 of shooting equipment 30 ~ 70 % gating phase interval and 0 ~90 % movement in the full phase interval was measured. If the full phase 0 ~ 90% with gating phase 30~70% of tumors in the liver and lung is shown the biggest difference compared to the motion and the size of the GTV was the largest difference in the I(inferior), full phase 0~90% degree of tumor motion only when a relatively large, gating phase to 30~70% of the tumor when the movement has been found that the reduced average 7.1mm. In the 4D-CT simulation comparing the motion value when the full phase 0~90 % and gating phase 30~70 % when the motion value, twice in the gating phase 30~70 % more than full phase 0~90 % showed a small movement value. The exposure to normal tissues, based on the results obtained from the 4D-CT simulation can be significantly alleviated, After treatment will reduce pain and disability in patients with radiation is expected to be able to effective treatment.

• Management & Information Systems Review
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• v.29 no.2
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• pp.97-118
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• 2010

This paper explores the mean and volatility spillover effects among Chinese, Korean, and the U.S. stock markets during the Asian and global financial crises. We found that, during the Asian Financial crisis, there was no mean spillover effect to the Chinese stock markets. However, there were reciprocal mean spillover effects between the U.S. and the Korean market. This implies that Korean market was open, while Chinese market was secluded from the international financial market at that time. The negative volatility spillover effect between the U.S. and China reinforces this finding. During the global financial crisis, there was reciprocal mean spillover effect between the U.S. and China, and between the U.S. and Korea. This may reflect the fact that Chinese market has opened to the international financial market. However, the volatility spillover effect does not exist between China and the U.S., while the U.S. and Korea has reciprocal volatility spillover effect to each other. These findings may imply that China is still in the process of opening her stock market to international investors.