• Nuclear Engineering and Technology
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• v.46 no.5
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• pp.641-654
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• 2014

A new computer code, named CORONA (Core Reliable Optimization and thermo-fluid Network Analysis), was developed for the core thermo-fluid analysis of a prismatic gas cooled reactor. The CORONA code is targeted for whole-core thermo-fluid analysis of a prismatic gas cooled reactor, with fast computation and reasonable accuracy. In order to achieve this target, the development of CORONA focused on (1) an efficient numerical method, (2) efficient grid generation, and (3) parallel computation. The key idea for the efficient numerical method of CORONA is to solve a three-dimensional solid heat conduction equation combined with one-dimensional fluid flow network equations. The typical difficulties in generating computational grids for a whole core analysis were overcome by using a basic unit cell concept. A fast calculation was finally achieved by a block-wise parallel computation method. The objective of the present paper is to summarize the motivation and strategy, numerical approaches, verification and validation, parallel computation, and perspective of the CORONA code.

• Journal of Electrical Engineering and information Science
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• v.3 no.2
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• pp.202-210
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• 1998

This paper is concerned with an efficient generation of stereoscopic views for complex virtual environments by exploiting frame coherence in visibility. The basic idea is to keep visible polygons throughout the rendering process. P-buffer, a buffer of image size, holds the id of the visible polygon for each pixel. This contrasts to the frame buffer and the Z-buffer which hold the color information and the depth information, respectively. For the generation of a consecutive image, the position and the orientation of the visible polygons in the current view are updated according to the viewer's movements, and re-rendered on the current image under the assumption that, when the viewer moves slightly, the visibility of polygons remains unchanged. In the case of stereoscopic views, it may not introduce much difficulty when we render the right(left) image using visible polygons on the (right) image only, The less difference in two images is, the easier the matching becomes in perceiving depth. Some psychophysical experiments have been conducted to support this claim. The computational complexity for generating a fight(left) image from the previous left(right) image is bounded by the size of image space, and accordingly. It is somewhat independent of the complexity of the 3-D scene.

• English Language & Literature Teaching
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• v.11 no.2
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• pp.19-34
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• 2005

Hypertext raises question to general assumptions about our conventional conceptions of education. In this essay, three kinds of learning-models are presented by the application of "writing" hypertext literature to the English education of the elementary school. These models, which I call the "scene-centered" system, give knowledge to learners in non-linear, non-sequential structure. The term "scene" is a single concept or idea composed of a single sub-text, which is to be made by the group of students. This system is focused on the collaborative composition of students. Students, by generating sub-texts and connecting texts, perform the educational activities to expand the source text. The "scene-centered" system is, to put it into a Barte's term, a "writerly text." But in order to "write," "reading" should be accompanied. So, this system is a learning model in which writing and reading are carried on simultaneously. In all the process, students play a role of multi-user, with three access rights: read, write, and annotate. So, students making use of hypertext systems will act as reader-authors. And teachers will take the new role in collaborative writing environment. No longer the central authoritarian evaluator, they will become consultants, co-writers, coaches of their students.

• Nuclear Engineering and Technology
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• v.34 no.3
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• pp.259-267
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• 2002

NFPA-803 has been referred as the Fire Protection Standard at the Nuclear Power Plants of Pressurized Water Reactor. This Standard has been used as the fire protection regulation, containing prescriptive requirements with deterministic methodology. Recently, with cumulative efforts by the U.S. Nuclear Regulatory Commission and Utilities in America to establish a new Standard, including a quantitative evaluation methodology, NFPA-805, the Performance-Based Standard for FIRE Protection for Light Water Reactor Electric Generating Plants was issued and approved by the American National Standards Institute as an American National Standard with an effective date of February 9, 2001. This paper presents an analysis result from the computer modeling for the fire simulation In addition, it proposes the idea that this kind of analytic method can be available for the facilities design of fire prevention and protection fields, as well as an evaluation for the fire suppression system with a quantitative analysis for the thermal phenomena in fire compartments in Nuclear Power Plants.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.856-859
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• 2005

The OPMT(Orientation-adjustable Patch-type Magnetostrictive Transducer) was proposed as a tool for generating and measuring the ultrasonic Lamb wave in plate type structures. This sensor has a lot of new features compared to the traditional piezo-type ultrasonic transducers. As an example, it does not need any kind of wiring for lunching or measuring ultrasonic waves. But it has also definite limitation for practical usage as a nondestructive testing tool in that it cannot help rotating the direction of ultrasonic wave manually. The idea for 'scanning OPMT' is proposed in this respect. Two kinds of basic ideas for rotating the wave direction not manually but electrically are proposed. The fabrication of the transducer and the testing for Identifying the primary characteristics are done for one of the proposed transducers. The results says that there are the possibilities as a new tool for NDE in that the proposed transducer follows well the characteristics of the traditional OPMT. But there are also the 1imitations to overcome.

• Journal of Intelligence and Information Systems
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• v.6 no.1
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• pp.35-50
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• 2000

Diverse requirements of users on web-based model management force a system agent to develop user-adaptive building a model in reality and providing an adequate solution method of the model. The relationship between models is important knowledge for the agent to effectively build a new model to adaptively adjust an existing model under a problem and to efficiently connect the new model into an adequate solution method. Since the generating process of the inter-model relationship is more difficult than the building a new model however the process mostly depends on the knowledge of operation research experts. Without the adequate scheme of the inter-model relationship the burden of the management for the agent increases rapidly and the quality of the services may worsen. This study shows that meta-knowledge generated from relationship between models is important for the user to build a model in reality and to acquire the solver appropriate to the model. The relationship that consists of common and exclusive objects between models can be represented by frames. The system under development to implement the idea includes user-adaptive ability which identifies a model through forward chaining method and searches the solver appropriate to the model by using the meta knowledge. We illustrate the meta knowledge with an applied delivery system in supply chain management.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.5
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• pp.21-27
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• 2021

The financial sector is one of the most important building blocks of the economy. When this sector efficiently implemented a well-crafted program on banking and financial system to translate financial activities to income-generating activity, economic growth will be realized. Hence, this study analyzed the effect of financial intermediation on economic growth and the existence of cointegrating relationship using time-series data from 1986 to 2015. The influence of financial intermediation in terms of bank credit to bank deposit ratio, private credit, and stock market capitalization and time trend to economic growth was estimated using ordinary least squares (OLS) multiple regression. The results showed that all the financial intermediation indicators and time trend exert significant effect on Gross Domestic Product (GDP) per capita. The positive sign of the time trend indicates that there is an upward trend in GDP per capita averaging approximately 0.06 percent annually. Furthermore, the cointegration test using the Johansen procedure revealed that there is a presence of long-term equilibrium relationship between financial intermediation and time trend and economic growth, and rules out spurious regression results. This study established the idea that financial intermediation in the Philippines has a significant and vital role in stimulating growth in the economy.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.68 no.1
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• pp.172-181
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• 2019

This paper deals with the problem of generating the energy optimal trajectory which is intended to enhance the target tracking performance of a passive homing missile. Noticing that the essence of passive target tracking is the range estimation problem, the target information gathered by passive measurements can be readily analyzed by introducing the range estimator designed in line-of-sight(LOS) frame. Moreover, for the linear filter structure of the suggested range estimator, the cost function associated with the target information is clearly expressed as a function of the line-of-sight rate. Based on this idea, the optimal missile trajectory maximizing the target information is obtained by solving the saddle point problem for an indefinite quadratic cost which consists of the target information and the energy. It is shown that, different from the previous heuristic approaches, the guidance command producing the optimal passive homing trajectory is produced by the modified proportional navigation guidance law whose navigation constant is determined by the weighting coefficient for target information cost.

• Journal of IKEEE
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• v.23 no.1
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• pp.68-73
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• 2019

This paper presents a novel fast shut-down scheme for Buck converter by using a coupled inductor. Generally, a controller for Buck converter stops generating PWM patterns in various fault cases: Overcurrent, Short circuit, or Overvoltage, but the inductor and capacitor keep supplying their stored energy to loads although the switching operations in Buck converter stopped. The stored energy in the inductor and capacitor could cause electrical stresses on breakers and safety problems. The main idea of the proposed fast shutdown scheme is to demagnetize the inductor core by using a coupled inductor, and its performance and operations are verified by using PSIM Simulation.

• The Korean Journal of Applied Statistics
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• v.35 no.6
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• pp.755-764
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• 2022

This paper is concerned with power transformations in estimating GARCH volatility. To handle a semi-parametric case for which the exact likelihood is not known, quasi-likelihood (QL) rather than maximum-likelihood method is investigated to best estimate GARCH via maximizing the information criteria. A power transformation is introduced in the innovation generating QL estimating functions and then optimum power is selected by maximizing the profile information. A combination of two different power transformations is also studied in order to increase the parameter estimation efficiency. Nine domestic stock prices data are analyzed to order to illustrate the main idea of the paper. The data span includes Covid-19 pandemic period in which financial time series are really volatile.