• Journal of Power Electronics
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• v.13 no.4
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• pp.692-700
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• 2013

This paper discusses the design of a novel synchronous reference frame (SRF) method that can extract the reference compensating current for single-phase shunt active power filters (APFs). Unlike previous SRF studies, the proposed method has an innovative feature that does not require a fictitious current signal. Other key features of the proposed strategy include frequency-independent operation, accurate reference current extraction, and relatively fast transient response. The effectiveness of the proposed method is investigated by conducting a detailed mathematical analysis. Results of the analysis confirm the superior performance of the suggested approach. Theoretical evaluations are confirmed by the experimental results.

• Transactions of the Korean Society of Automotive Engineers
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• v.1 no.3
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• pp.22-33
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• 1993

A theoretical analysis of predicting the detailed motion of a piston-crank mechanism within piston-guide clearance is presented, and the analysis is applied to the piston motion in a gasoline engine. A piston movement program is developed to calculate the piston attitude relative to the bore, the piston to bore impact velocity and kinetic energy loss and the net transverse force acting on the piston. This paper presents the formulation of a set of differential equations governing the transverse and rotational motion of a piston. These equations of motion were solved by well established Runge-Kutta method. As a result of this study, it is possible to predict the effects of piston geometry and piston pin offset on a piston motion and kinetic energy loss.

• Proceedings of the IEEK Conference
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• summer
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• pp.249-253
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• 2004

Wavelet transform (WT) has attracted most engineers and scientists because of its excellent properties. The coherence of practical approach and a theoretical basis not only solves currently important problems, but also gives the potential of formulating and solving completely new problems. It has been show that multi-resolution analysis of Wavelet transforms is good solution in speech analysis and threshold of wavelet coefficients has near optimal noise reduction property for many classes of signals. This paper proposed applications of wavelet in speech processing: pitch detection, voice-unvoice (V -UV) decision, denoising with the detailed algorithms and results.

• KIEAE Journal
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• v.2 no.1
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• pp.21-32
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• 2002

This study aims to find out the way of revitalizing of natural riverfront space in terms of ecological aspect. At the first part, theoretical made in terms of concept, planning aspects and techniques which were main bases for the study. It begins by explaining the concept of ecological riverfront space, the main aspect and techniques of its planning. After this, it analysis eight cases(four cases in Korea, Swiss, Germany, America and Japan) in terms of the objects, planning techniques and the results of development. It continues by making detailed analysis according to four objectives like 'protection from flood', 'quality of the river', 'ecological preservation' and 'active usage of riverfront space'. It ends by evaluating the relationship between objectives and the planning which will be adapted to the future development of riverfront space with ecological aspect. In conclusion, hereafter will propose desirable design-direction for revitalization about riverfront space about ecological aspect design in urban.

• Journal of Electrical Engineering and Technology
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• v.9 no.5
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• pp.1592-1601
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• 2014

In this study, a novel single phase soft switched power factor correction (PFC) converter is developed with active snubber cell. The active snubber cell provides boost switch both to turn on with zero voltage transition (ZVT) and to turn off with zero current transition (ZCT). As the switching losses in the proposed converter are too low, L and C size can be reduced by increasing the operating frequency. Also, all the semiconductor devices operate with soft switching. There is no additional voltage stress in the boost switch and diode. The proposed converter has a simple structure, low cost and ease of control as well. It has a simple control loop to achieve near unity power factor with the aid of the UC3854. In this study, detailed steady state analysis of the proposed converter is presented and this theoretical analysis is verified by a prototype of 100 kHz and 500 W converter. The measured power factor and efficiency are 0.99 and 97.9% at full load.

• Structural Engineering and Mechanics
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• v.29 no.1
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• pp.17-35
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• 2008

Neglecting the real joint behaviour in frame analysis may result in unrealistic predictions of the response and reliability of steel frames. The reliability of the prediction of main joint properties according to the component method (Eurocode 3-Part 1.8) still remains open to further investigation. The first step toward the solution is to compare the theoretical expressions given in EN 1993-1-8 and the experimental results. With that goal in mind six nominally the same, but really different specimens of welded beam-to-column joints subjected to static load were tested. The specimens present a combination of nominally identical structural elements produced in different European mills. This paper provides these tests, as well as their detailed evaulation and interpretation. All three joint structural properties (rotational stiffness, moment resistance and rotation capacity) have been considered. Four models for determining the plastic resistance out of experimental Mj-${\phi}$ curves have been applied. The results that have been discussed in detail, point to the fact that EN 1993-1-8 underestimates the real structural properties of the tested type of joint, as well as to the conclusion that detailed research of this problem needs to be conducted using the probabilistic reliability methods.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.1
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• pp.77-82
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• 2013

A cyclone separator has been widely used in various industrial processes for removing fine particulate matter because it is easy to fabricate, cost effective, and adaptable to extremely harsh conditions. However, owing to the complex flow field in cyclones, a complete understanding of the detailed mechanisms of particulate removal has not yet been gained. In this study, a theoretical analysis was performed for calculating the collection efficiency and cut-off size in cyclones by taking into account the effects of geometrical and flow parameters. The collection efficiency and cut-off size values predicted by the theoretical model showed good agreement with experimental measurements for particles with a diameter of $0.5-30{\mu}m$. It was also revealed that the surface friction, along with the flow and geometrical parameters, has a significant effect on the cyclone performance.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.36 no.4
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• pp.351-361
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• 2023

The purpose of this paper is to help those who research and develop solar cells in university laboratories and industrial sites understand the most basic and important quantum efficiency measurement and analysis method in analyzing solar cell performance. Starting with the definition of quantum efficiency, we calculate the theoretical current density according to the band gap of the solar cell material from the solar spectrum, along with a detailed introduction to the measurement and analysis methods, and measure and analyze the theoretical current density and quantum efficiency. We discuss in depth how to analyze the performance of solar cells through Quantum efficiency measurement and analysis of solar cells is a very useful method that can give intuition to solar cell performance analysis as it can analyze solar cells according to depth (front emitter, bulk, rear surface). Students and researchers who study solar cells with a deep understanding of theoretical current density and quantum efficiency measurement analysis are expected to use it as a basis for analyzing solar cell performance.

• Journal of the Korean Society for information Management
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• v.20 no.2
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• pp.177-198
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• 2003

The most significant part of this study is in developing an experimental medel of user-friendly PDL. This study proposes both theoretical (conceptual) and physical (operational) models. The theoretical model includes the analysis on various factors and the realtionsips among factors which have a serious impacts on the design, building, and managing of PDL. And the physical model shows the shows the detailed structure and process which could be useful for both PDL designers and managers. Also provided is the images of major user interfaces, of which a PDL would be developed on the basis of the proposed medel in near future.

• East Asian Journal of Business Economics (EAJBE)
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• v.4 no.2
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• pp.1-11
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• 2016

This study investigated commercial power theory of traditional market through the analysis of literature review. Consumers' store selection models are made up a theory based on normative hypothesis, theory of mutual reaction, utility function estimation model, and cognitive-behavioral model. Detailed models are as follows. Normative hypothesis based theory is divided into Reilly's retail gratification theory and Converse's revised retail g ratification theory. Interaction theory is composed of Huff's probability gratification theory, MCI model and Multi-nominal Logit Model (MNL model). There are four models in retail organization position theory such as central place theories, single store position theory, multi store position - assign model, and retail growth potential model. In case of single store position theory, theoretical and empirical techniques have developed for a decision to optimum single store position. Those are like these, a check list, the most simple and systematic method, analogy, and microanalysis technique. Aforementioned models are theoretical and mathematical commercial power measurement and/or model. The study has rather limitations because the variation factors included in formula are only a part of actual commercial power. Therefore, further study shall be made continuously to commercial power areas and variables.