• Journal of the Institute of Electronics Engineers of Korea TC
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• v.38 no.3
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• pp.35-43
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• 2001

A method is newly presented to synthesize the modal impedances satisfying the desired coupling factor of a reflective (or hack ward) coupled-line. The synthesis is achieved by optimal perturbations of repeating null points of lobes inherent to the solution of the first order nonlinear differential equation for coupling. It is based on the synthesis method of nonlinear source distribution functions for the prescribed space factor pattern in the one-dimensional array antenna. Here, the conventional synthesis method for the even distribution function is extended to the odd case. Resulting modal impedances will have continuously varying profiles. The design procedure of asymmetrical and symmetrical couplers corresponding to the even and odd distribution functions, is examplified to show the generalization and the simplicity of the proposed method.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.3
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• pp.16-22
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• 2013

A general characterization procedure based on the extraction of a 2n-port admittance matrix corresponding to n uniform coupled lines on the multi-layered substrate using the Finite-Difference Time-Domain (FDTD) technique is presented. In this paper, the frequency-dependent normal mode parameters are obtained from the 2n-port admittance matrix to analyze multi-layered asymmetric coupled line structure, which in turn provides the frequency-dependent propagation constant, effective dielectric constant, and line-mode characteristic impedances. To illustrate the technique, several practical coupled line structures on multi-layered substrate have been simulated. Especially, embedded conductor structures have been simulated. Comparisons with Spectral Domain Method are given, and their results agree well. It is shown that the FDTD based time domain characterization procedure is an excellent broadband simulation tool for the design of multiconductor coupled lines on multilayered PCBs as well as thick or thin hybrid structures.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.1
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• pp.24-31
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• 2006

In the present study, a strongly coupled analysis code is developed for transonic flutter analysis. For aerodynamic analysis, two dimensional Reynolds-Averaged Navier-Stokes equation was used for governing equation, and ε-SST for turbulence model, DP-SGS(Data Parallel Symmetric Gauss Seidel) Algorithm for parallelization algorithm. 2 degree-of-freedom pitch and plunge model was used for structural analysis. To obtain flutter response in the time domain, dual time stepping method was applied to both flow and structure solver. Strongly coupled method was implemented by successive iteration of fluid-structure interaction in pseudo time step. Computed results show flutter speed boundaries and limit cycle oscillation phenomena in addition to typical flutter responses - damped, divergent and neutral responses. It is also found that the accuracy of transonic flutter analysis is strongly dependent on the methodology of fluid-structure interaction as well as on the choice of turbulence model.

• The Transactions of the Korea Information Processing Society
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• v.7 no.11
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• pp.3592-3602
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• 2000

Image processing consist of image analysis and classification. The one is extracting of feature value in the image. The other is segimentationof image that have same properiv. A novel approach for the analysis and classification of tezture images based on statistical texture prunitive estraction are proposed. In this approach, feature vector extracting is based on stalisucal method using apatial dependence of grey level and use general lexture proerty. In is advantageous that not effiected on structure and type of lexture. These components describe the amount of roughness and softness of texture images Two leatures. Moment and Homogeneity, are componted from GLCM(gray level co-occurrence matrices) of the lexture promitive to charactenize statisical properties of the image. We show the successful experimental results by considerationof these two components fro the analysis and classificationto regular and irregular texture images.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.5
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• pp.221-229
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• 1999

We examined the governing factors of fatigue limit in annealed and austempered ductile iron specimens machined micro hole(dia.<0.4mm) in rotary bending fatigue test. Also, the quantitative relationship between fatigue limit and maximum defect size in specimens was investigated. Artificial defect(micro-pit type, dia.<0.4mm) on specimen surface did not bring about an obvious reduction of fatigue limit in austempered ductile iton(ADI) as compared with annealed ductile iron. According to the investigation of ${\sqrt{area}}_c$ which is the critical defect size to crack initiation at artificial defect, ${\sqrt{area}}_c$ of ADI was larger than that of annealed ductile iron. This shows that the situation of crack initiation at artificial defect in ADI is more difficult in comparison with annealed ductile iron. Maximum defect size is one of the important parameters to predict fatigue limit. And, the quantitative relationship, between the fatigue limit ${\sigma}_{\omega}$ and the maximum defect size ${\sqrt{area}}_{max}$ can be expressed to ${\sigma}_{\omega}^n{\cdot}{\sqrt{area}}_{max}=C_2$ where, $C_2$ are constant. Moreover, it is possible to explain the difference in fatigue limit between, austempered and annealed ductile iron by introducing the parameter ${\delta}(=N_{sg}/N_{total})$in a plain spectimen.

• The Korean Journal of Financial Management
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• v.21 no.2
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• pp.211-233
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• 2004

This purpose of paper is to propose a European option pricing formula when the rate of return follows the leptokurtic distribution instead of normal. This distribution explains well the volatility smile and furthermore the option prices calculated under the leptokurtic distribution are shown to be closer to the market prices than those of Black-Scholes model. We make an estimation of the implied volatility and kurtosis to verify the fitness of the pricing formula that we propose here.

• Journal of the Korean Society of Safety
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• v.18 no.3
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• pp.154-160
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• 2003

Uncertain time delay happens when the process reads the sensor data and sends the control input to the plant located at a remote site in distributed control system. As in the case of data network using TCP/IP, VDN that integrates both device network and data network has uncertain time delay. Uncertain time delay can cause degradation in performance and stability of distributed control system based on VDN. This paper first investigates the transmission characteristic of VDN and suggests a control scheme based on the Smith's predictor to minimize the effect of uncertain varying time delay. The validity of the proposed control scheme is demonstrated with real-time velocity control of DC servo motor located in remote site.

• Journal of The Korean Association For Science Education
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• v.42 no.3
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• pp.357-370
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• 2022

In this paper, we developed an augmented reality learning tool suitable for chemical bond learning and proposed a process-oriented guided inquiry learning using mobile augmented reality (POGIL-MAR) to find out how it affects science achievement, science learning motivation and learning flow. Participants were 139 10^th-grade students from a coeducational high school in Gyeonggi-do, and they were randomly assigned to the control group (TL), the treatment group 1 (POGIL), and the treatment group 2 (POGIL-MAR). They learned the concept of the chemical bond from the Integrated Science subject for four class periods. Results of two-way ANCOVA revealed that the POGIL-MAR group scored significantly higher than the other groups in a science achievement test, science learning motivation test, and learning flow test, regardless of their prior science achievement. In addition, in the case of the low-level group, the POGIL-MAR group showed a statistically significant improvement in achievement compared to the TL and POGIL groups. The MANCOVA analysis for sub-factors of science learning motivation show that the POGIL-MAR group had significantly higher scores in intrinsic motivation, career motivation, self-determination, self-efficacy, and grade motivation. In particular, the interaction effect between the teaching and learning method and the level of prior achievement was significant in the intrinsic motivation. Meanwhile, the MANCOVA analysis for sub-factors of learning flow show that the POGIL-MAR group had significantly higher scores in clear goals, unambiguous feedback, action-awareness merging, sense of control, and autotelic experience. Based on the results, educational implications for effective teaching and learning strategy using mobile augmented reality are discussed.

• Journal of Korean Philosophical Society
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• v.129
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• pp.315-339
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• 2014

Diese Abhandlung untersucht Jacobis ${\ddot{U}}ber$ die Lehre Spinoza und den von diesem veranlassten Spinoza-Streit. Damit sie $enth{\ddot{u}}llt$ zuerst Jacobischen Zusammenhang zwischen transzent und immanent und folgt auf seine Wirkungsgeschichte in der Moderne. Ich rekonstruiere den Streit zwischen Jacobi und Lessing und danach interpretiere dessen Rezeption durch Hegel und Schleiermacher. Lessing stellt anstatt der traditionellen Begriffe der Gottheit ἑν ${\kappa}{\alpha}{\iota}$ ${\pi}{\alpha}{\nu}$ auf. $Demgegen{\ddot{u}}ber$ behauptet Jacobi Salto mortale um ihn ${\ddot{u}}berschreiten$ zu $k{\ddot{o}}nnen$, indem er Lessing als Pantheist und Atheist bestimmt. Salto mortale bei Jacobi ist der Sprung zu dem ${\ddot{U}}bernat{\ddot{u}}rlichen$ und dem Glaube. Der Streit zwischen Jacobi und Lessing ist der zwischen dem Naturalismus und ${\ddot{U}}bernaturalismus$ und $dar{\ddot{u}}berhinaus$ der zwischen dem Athismus und Theismus. $W{\ddot{a}}hrend$ die Natur der Inbegriff der Bedingten ist, ist Gott der absolute Anfang der Natur $au{\ss}erhalb$ des Naturzusammenhangs. $W{\ddot{a}}hrend$ Spinoza Gott im $nat{\ddot{u}}rlichen$ Zusammenhang begreift, $fa{\ss}t$ Jacobi den im ${\ddot{u}}bernat{\ddot{u}}rlichen$ auf. Deus sive natura bei Spinoza $ver{\ddot{a}}ndert$ sich Gott im Menschen bei Jacobi. Gott im Menschen ist nichts anders als das Prinzip des Lebens und das aller Vernuft. In diesem Zusammenhang $fa{\ss}t$ Hegel Gott als Geist denn Subjekt des Lebens auf und $h{\ddot{a}}lt$ das Wesen des Geistes $f{\ddot{u}}r$ die sich selbst vermittelnde Bewegung. Dies zeigt sich als die Spinoza ${\ddot{u}}berbietende$ Immanenzphilosophie. $Demgegen{\ddot{u}}ber$ behauptet Schleiermacher die Einheit des Endlichen und Unendlichen in der $religi{\ddot{o}}sen$ Anschuung. Die Verbindung von Mensch und Gott ist die im Endlichen immanent bleibende Anschauung der $g{\ddot{o}}ttlichen$ Eigenschaft. Dies zeigt das transzendente im immanenten.

• Journal of the Korean Society for Library and Information Science
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• v.32 no.2
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• pp.259-276
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• 1998

This study is to contribute to develop adaptive information systems meeting inside information needs as well as represented information needs, and dealing with every levels of users and user's preferences. Also, this study is to present a method of developing adaptive information system through developing user profile using machine teaming and decision tree, applying relevance feedback using merged vector, and applying user feedback.