• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1989.06a
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• pp.21-25
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• 1989

Theory and experimental results are presented to show the possibility of using a dielectric rod resonator method for characterizing dielectric materials at microwave frequency. The measuring structure is a resonator made up of a cylindrical dielectric rod placed between two parallel conducting plates. In this system, the TE$\_$011/ mode frequency was adapted to minimize the effect of the air-gap between the rod and the conducting plates. The dielectric properties are computed from the resonance frequencies, structure dimensions and 3-dB bandwidth.

• Electrical & Electronic Materials
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• v.7 no.2
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• pp.107-116
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• 1994

In the manufacturing of VLSI circuits, variations of device characteristics due to the slight differences in process parameters drastically aggravate the performances of fabricated devices. Therefore, it is very important to establish optimal process conditions in order to minimize deviations of device characteristics. In this paper, we used one-dimensional process simulator, SUPREM-II, and two dimensional device simulator, MINIMOS 4.0 in order to extract optimal process parameter which can minimize changes of the device characteristics caused by process parameter variation in the case of short channel nMOSFET and pMOSFET device. From this simulation, we have derived the dependence relations between process parameters and device characteristics. Here, we have suggested a method to extract process parameters from design trend curve(DTC) obtained by these dependence relations. And we have discussed short channel effects and device limitations by scaling down MOSFET dimensions.

• Journal of Information Technology Applications and Management
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• v.17 no.3
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• pp.43-56
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• 2010

Completely Automated Public Turing test to tell Computers and Humans Apart or CAPTCHA has received remarkable attention. Deciphering distorted texts is still a human task. The current CAPTCHA mainly requires users to read English alphabets. As such, Thai CAPTCHA may be the choice for Thai online practitioners. However, no published work has examined how Thai online practitioners perceive CAPTCHA. This study thus attempts to fill this void. Based on the 112 number of usable online questionnaire submission, Thai online practitioners are all aware of CAPTCHA. Also, nine out of ten samples identified correctly the prime benefits of CAPTCHA. Using exploratory factor analysis, their attitude towards CAPTCHA was classified into two dimensions. They perceived (1) drawback of general CAPTCHA and (2) feasibility of Thai CAPTCHA. In addition to extending our insight into application of CAPTCHA, policy-makers responsible for electronic commerce in Thailand could initiate plans in response to Thai online practitioners' perception.

• Journal of Korean Elementary Science Education
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• v.29 no.4
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• pp.389-400
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• 2010

This study is focused on analyzing effects of Self-regulated learning on Academic self-regulation, Science achievement and Science Related Affective Domains. The subjects of this study were sampled from fifth grades of a elementary school in Seoul, 61 students. One class (31 students) out of selected two classes was applied to Self regulated learning Teaching Model, the other (30 students) took conventional methods of teaching. The experiment proceeded for 21 weeks, 51 times of classes. According to the results of this study, Self-regulated learning improved the children's Academic self regulation ability. Self-regulated learning improved the children's science achievement. Self-regulated learning improved the children's Science Related Affective Domains. Furthermore, six distinct dimensions of Academic self-regulation have correlation with scientific attitudes, interests of Science Related Affective Domains.

• Culinary science and hospitality research
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• v.14 no.4
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• pp.269-282
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• 2008

Quality is recognized as one of the key components of business strategies. In this respect, this study aims to investigate quality factors that influence customer satisfaction and loyalty in Korean Tofu restaurants and promote the quality improvement in their service operations. The experimental data were collected from the questionnaire answered by 130 customers in Seoul and Kyonggi area. They were statistically analyzed using SPSS Win.12.0. For statistical analysis, frequency, factor analysis, reliability analysis, and regression analyses were conducted. The results of the analyses show that two dimensions such as "empathy" and "IT use" influence the satisfaction of customers. "Empathy", "tangibles", "well-being food", and "customer satisfaction" were identified as critical factors influencing the loyalty of customers.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.105.6-105
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• 2001

Fish schools behave like a single organism and offer a considerable survival advantage. In our simulations, the fish school is well organized and behaves like a single creature depending solely on the interactions among individuals without having any director fish. This kind of system can be said as the typical one of "Complex Systems". We make clear the validity of fractal analyses to evaluate fish school movements through evaluation of both the simulated movements and the real sardine movements taken by video tape. The analyses showed that we need two kinds of fractal dimensions (D$_1$, D$_2$) to fit to the observations; the one(D$_1$) corresponds to smaller coarsening levels and D$_2$ does to larger coarsening levels. The double linear analyses in ...

• Journal of the Korean Institute of Telematics and Electronics
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• v.25 no.1
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• pp.72-80
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• 1988

In this paper, new adaptive interframe filtering methods have been proposed to separate the luminance and chrominance components in NTSC composite signals. In thess methods, the composite signals are adaptivelty processed in three dimensions according to the local change or movement of the picture. For interframe processing, two algorithms have been proposed which adapt three filters in the horizontal, vertical and temporal directions to the magnitude f detection signal dependent upon both the movement and local change of the picture. The three kind of filters have been used at the sampling rate of four times the subcarrier frequency. The various quantitative measures have been introduced to compare the objective performance of the conventional methods and that of proposed ones by computer simulation.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2002.11a
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• pp.366-369
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• 2002

Two artificial neural networks (ANN) are used to model the electric coupling probe in the combline resonators. One is used to analyze and synthesize the electric probe, and the other is used to correct errors between the results of the analysis and the synthesis ANNs and the fabrication results. The ANNs for the analysis and the synthesis of the electric probe are trained using the physical dimensions of the electric probe and the corresponding coupling bandwidth which is obtained using the finite element method. The ANNs for the error correction are trained using a very small set of the measurement results. Once trained, the ANN models provide the correct result approaching the accuracy of the measurement. The results from the ANN models show fairly good agreement with those of the measurement and they can be used as good initial design values.

• Journal of computational fluids engineering
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• v.1 no.1
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• pp.19-25
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• 1996

A multiblock grid generation has been developed to be reliably used for a Navier-Stokes simulation of the turbomachinery flow-fields A multiblock structure simplifies the creation of structured H-grids about complex turbomachinery geometries and facilitate the creation of a grid in the tip flow region. The numerical algorithm adopts the combination of the algebraic and elliptic method to create the internal grids efficiently and quickly. The grid refinement process is enhanced by developing strategies to utilized Bezier curves and splines along with weighted transfinite interpolation technique and by formulating the grid-imbedding method for the viscous boundary-layer meshes. For purposes of illustration, the grid generator is applied to the high turning turbine rotor blades. Two different types of computational grids are provided to be compared with respect to the grid adaptation to the flow simulations. Extension to three-dimensions was done to show the possibility of its application to the tip-flow simulations. The grid quality of the multiblock structure is good in the passages, with gloval orthogonality and adequate smoothness.

• Journal of Mechanical Science and Technology
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• v.19 no.9
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• pp.1821-1832
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• 2005

This study realizes the conceptual method to predict combustion instability in actual full-scale combustion chamber of rocket engines by experimental tests with model (sub-scale) chamber. The model chamber was designed based on the methodologies proposed in the previous work regarding geometrical dimensions and operating conditions, and hot-fire test procedures were followed to obtain stability boundaries. From the experimental tests, two instability regions are presented by the parameters of combustion-chamber pressure and mixture (oxidizer/fuel) ratio, which are customary for combustor designers. It is found that instability characteristics in the chamber with the adopted jet injectors can be explained by the correlation between the characteristic burning or mixing time and the characteristic acoustic time: In each instability region, dynamic behaviors of flames are investigated to verify the hydrodynamically-derived characteristic lengths of the jet injectors. Large-amplitude pressure oscillation observed in upper instability region is found to be generated by lifted-off flames.