• The Transactions of the Korean Institute of Electrical Engineers P
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• v.67 no.2
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• pp.63-69
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• 2018

In this paper, the operation principle of a bi-directional switch type resonant AC link snubber circuit was described, together with the practical design procedure, which employs in the proposed power module bridge package type resonant AC link snubber. The novel prototype of power module bridge package type resonant AC link snubber-assisted voltage type sinewave soft switching PWM inverter using IGBT power module was demonstrated herein. It was verified that both the auxiliary power switches in this resonant AC link snubber circuit and the main power switches commutate under the condition of soft switching commutation principle. In addition, the power losses of the new soft switching inverter treated here were analyzed by implementing the experimental data of the IGBT and diode v-i characteristics in addition to switching power loss characteristics into our original computer simulation software developed by the authors. Then, the voltage type sinewave soft switching PWM inverter was high efficiency than that of hard switching PWM inverter, along with performance operation waveforms. In the future, the comparative feasibility study of power module bridge type resonant AC link snubber and its related soft switching inverter in addition to the other types resonant snubber assisted soft switching inverter should be done from a practical point of view.

• Structural Engineering and Mechanics
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• v.87 no.6
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• pp.529-540
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• 2023

A novel laminated-hybrid-composite-beam (LHCB) of glass-epoxy infused with flyash and graphene is constructed for this study. The conventional mixture-rule and constitutive-relationship are modified to incorporate filler and lamina orientation. Eringen's non-local-theory is used to include the filler effect. Hamilton's principle based on fifth-order-layer-wise-shear-deformation-theory is applied to formulate the equation of motion. The analogous shear-spring-models for LHCB with multiple-cracks are employed in finite-element-analysis (FEA). Modal-experimentations are conducted (B&K-analyser) and the findings are compared with theoretical and FEA results. In terms of dimensionless relative-natural-frequencies (RNF), the dynamic-response in cantilevered support is investigated for various relative-crack-severities (RCSs) and relative-crack-positions (RCPs). The increase of RCS increases local-flexibility in LHCB thus reductions in RNFs are observed. RCP is found to play an important role, cracks present near the end-support cause an abrupt drop in RNFs. Further, multiple cracks are observed to enhance the nonlinearity of LHCB strength. Introduction of the first to third crack in an intact LHCB results drop of RNFs by 8%, 10%, and 11.5% correspondingly. Also, it is demonstrated that the RNF varies because of the lamina-orientation, and filler addition. For 0° lamina-orientation the RNF is maximum. Similarly, it is studied that the addition of graphene reduces weight and increases the stiffness of LHCB in contrast to the addition of flyash. Additionally, the response of LHCB to moving mass is accessed by appropriately modifying the numerical programs, and it is noted that the successive introduction of the first to ninth crack results in an approximately 40% to 120% increase in the dynamic-amplitude-ratio.

• Korean journal of communication and information
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• v.26
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• pp.291-326
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• 2004

This study explores the process within which whereas the majority of Korean people agree on the principle of the unification policy, the opinions about the concrete policy alternatives related to the principle do not converge. To account for this phenomenon, a.k.a. 'the principle-policy puzzle in public opinion', this study constructs and tests a covariance structural model with the explanatory variables such as political knowledge, political ideology, authoritarian personality, social distance, and the evaluation of the president. In addition, the interaction effects of the interpretive frames regarding the unification policy and political knowledge along with the main effects of socio-demographic variables are tested to explain the degree to which people show the gap between the agreements on the unification principle and policy alternatives. A sample of 600 Seoul people are recruited to provide the data for the analysis of structural equation modeling. Ie was found that the proposed model receives empirical supports from the data. In particular, political knowledge and authoritarian personality play key roles in accounting for the complex process of public opinion in the 'principle-policy puzzle'. The findings were discussed in terms of the representations of the Engagement policy in the mass media and the public perception of them.

• Bulletin of the Korean Chemical Society
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• v.29 no.2
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• pp.319-322
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• 2008

The viability of acetylene addition in each step of aromatic formation initiated by vinyl radical and acetylene also with its competition with structure rearrangement is investigated by determining optimal geometries and barrier and reaction energies using quantum mechanical methods. In principle, the addition reaction has more difficult in term of free energy and enthalpy compared to geometry arrangement. Under combustion conditions, i.e. T = 1200 K, acetylene addition is unfavorable mechanism as the barrier energy values rise much higher than that of geometry arrangement. However, in longer chain hydrocarbon case, e.g. n-CxHx+1 where x ³ 8, C-C bond rotation is rather difficult and requires high energy to form a ring structure, elongation chain is preferable.

• Korean Journal of Heritage: History & Science
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• v.50 no.2
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• pp.62-79
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• 2017

The principle of repairing the architectural heritage in China was first presented by Liangsicheng of Society for Research in Chinese Architecture in the 1930s, and it was stated as "Restoration of Historic Condition or Preservation of Existing Condition" in 1961 in the "Provisional Regulations on the Protection and Management of Cultural Relics" after various repair experiences under the social and political background of the 1950s. Restoration of historic condition generally means restoration to original shape, and because architectural heritage was often repaired based on similar principle in Korea and Japan in the early and mid 20th century, it can be said that the restoration of historic condition was a universal and leading principle in this period in Northeast Asia. In China, however, the preservation of existing condition is equally specified along with the restoration of historic condition. When considering the leading trend of the time, it seems to be rather unexpected, which leads to questions about the formation process and meaning. The research on Liangsicheng, which first suggested the principle of repair, is very important, but there is a lack of three-dimensional analysis of his principles compared with active research on international principles in China. In order to understand the process of formation and its meaning of the principle of repair in China, we first need to analyze the principle proposed by Liangsicheng, and it is necessary to comprehensively examine how the principle have changed under the social background surrounding architectural heritage conservation after the founding of the People's Republic of China(PRC). In this paper, we first show that Liangsicheng has proposed a principle of restoration of historic condition with important values in the originality, and at the same time he opened the possibility of preservation of existing condition for the result of value judgment or realistic reason. In addition, we examine the process of equalizing preservation of existing condition with a restoration of historic condition as a realistic principle due to the influence of Soviet architectural heritage conservation system and Chinese economic development oriented policy after the founding of PRC.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10b
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• pp.1718-1723
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• 1991

The determination of a production sequence is an important problem in a batch process operation. In this paper a new algorithm for a near optimal production sequence of N product in an M unit serial multiproduct batch process is proposed. The basic principle is the same as that of Johnson's algorithm for two-unit UIS system. Test results on a number of selected examples exhibit the superiority over previously reported results. In addition, a tabulation technique is presented to calculate the makespan of a given sequence of production for all processing units under UIS mode.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.7
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• pp.1569-1574
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• 2005

In this paper, I propose an intelligent credit rating system using a bankruptcy prediction model based on support vector machines (SVMs). SVMs are promising methods because they use a risk function consisting of the empirical error and a regularized term which is derived from the structural risk minimization principle. This study examines the feasibility of applying SVM in Predicting corporate bankruptcies by comparing it with other data mining techniques. In addition. this study presents architecture and prototype of intelligeht credit rating systems based on SVM models.

• Korean Journal of Mathematics
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• v.11 no.1
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• pp.1-7
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• 2003

In this paper, we introduce two types of algebraic operations on fuzzy numbers using piecewise linear functions and then show that the Zadeh implication is smaller than the Diense-Rescher implication, which is smaller than the Lukasiewicz implication. If ($f$, *) is an available pair, then $A*_mB{\leq}A*_pB{\leq}A*_jB$.

• Proceedings of the KIPE Conference
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• 1998.07a
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• pp.14-19
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• 1998

This paper has described about principle and form of proposed circuit made use of soft switching technology ZVS(Zero-Voltage-Switching) to reduce turn on and off loss at switching. also, the analysis of the proposed circuit has described by using normalized parameter and operating characteristics have been evaluated as to switching frequency and parameters. In addition, this paper proves the propriety of theoretical analysis in terms of the experiments.

• Proceedings of the KIPE Conference
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• 1998.07a
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• pp.35-38
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• 1998

In this paper, we present a new SVPWM strategy for a 3-level inverter. This SVPWM method is easily implemented without switching table like SVPWM. In addition, with proposed method, we can also keep the voltage balancing of DC-link capacitors and guarantee minimum on/off time of the devices. The principle of the proposed SVPWM method is described in detail, and its implementation method is also proposed. The usefulness of the proposed SVPWM method is verified through the simulation using MATLAB/Simulink.