• Steel and Composite Structures
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• 제11권2호
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• pp.169-181
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• 2011

The behavior of connections between open sandwich slabs and double steel skin composite walls in steel plate-concrete(SC) structure is investigated by a series of experimental programs to identify the roles of components in the transfer of forces. Such connections are supposed to transfer shear by the action of friction on the interface between the steel surface and the concrete surface, as well as the shear resistance of the bottom steel plate attached to the wall. Experimental observation showed that shear transfer in slabs subjected to shear in short spans is explained by direct force transfer via diagonal struts and indirect force transfer via truss actions. Shear resistance at the interface is enhanced by the shear capacity of the shear plate as well as friction caused by the compressive force along the wall plate. Shear friction resistance along the wall plate was deduced from experimental observation. Finally, the appropriate design strength of the connection is proposed for a practical design purpose.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1999년도 전력전자학술대회 논문집
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• pp.278-281
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• 1999

In a utility interactive photovoltaic system, a PWM inverter is used for the connection between the photovoltaic arrays and the utility. The DC current becomes pulsated causes the distortion of the AC current waveform. This paper presents the reduced pulsation of DC input current by operating the inverter with buck-boost chopper in the discontinuous conduction mode. The DC current with contains harmonics component is analyzed by means of separating into two terms of a ripple component and a direct component. The constant DC current without pulsation is supplied from photovoltaic array to the inverter. The proposed inverter system provide a sinusoidal AC current for domestic loads and the utility line with unity power factor.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1999년도 전력전자학술대회 논문집
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• pp.210-213
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• 1999

A battery is the device that transforms the chemical energy into the direct-current electrical energy directly without a mechanical process. Unit cells are connected in series to obtain the necessary voltage, while being connected in parallel to organize capacity for load current and to decrease the internal resistance for corresponding the sudden shift of the load current. The circular-current, however, could be occurred when the system is driven in parallel. As a result, the new batteries are heated by over-change and discharge, and the over charge current makes to increase the rust of the positive grid and consequently the shortened life of the new batteris would be shown. In this paper, the internal resistance of charge and discharge will be balanced, through inserting the resistance into the system by way of calculation of the changed amount of internal resistance.

• ETRI Journal
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• 제10권4호
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• pp.146-160
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• 1988

The purpose of the present study is to build a model to determine the structure of long-term quasi-optimal rates of local and toll telephone services. The outline of this study is as follows : Telephone business, providing social goods, is capital-intensive industry which needs huge fixed cost to operate exchanges and telephone networks nationwide. The nature of above industry justifies the market structure of telephone business to be natural monopoly and makes a good reason for government's direct regulation, that is, price regulation. Three is a gap between the present rates and the quasi-optimal ones because some administrative processes intervene in rate making process before execution. On the above diagnostic basis, the present study made an empirical test for the optimality of present rates structure in connection with Ramsey-Boiteux model to maximize the sum of producer's and consumer's surplus and also the current study proposed a qusasi-optimal rates structure for better market performance. From the empirical analysis, we can deduce a policy recommendation the local price should be increased to 47% whereas toll price decreased to 24% in order to improve the net welfare worth of 32.6 billion won.

• Journal of Mechanical Science and Technology
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• 제19권4호
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• pp.927-935
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• 2005

In the present paper the dynamics of the structure varying multibody systems caused by stick-slip motion with two-dimensional dry friction are analyzed. The methods to determine friction force both in stick and slip states are described. The direct method of considering the wagon bogie system as a structure varying system was used to consider two dimensional friction at the wheelset-side frame connection. The concept of friction direction angle used to determine the friction force components of two-dimensional dry friction both in the stick and slip motion states was used. A speed depended friction coefficient was used and described approximately by hyperbolic secant function. All switch conditions were derived and friction forces both for stick and slip states. Some simulation results are provided.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 춘계학술대회 논문집
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• pp.1146-1152
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• 2005

Now many metropolitan electric railways are being constructed on the metropolitan area. But railways now in service have some inefficiency. These railways are operated like subways, for example, all slow trains and fixed train set. So this paper proposes the methods of improvement. For making rapid train, it is showed ' philosophy of rapid train ' that makes rapid train to be main service. And for effective operation, it is introduced flexible train set and 'separation-unification operation'. And for smart railway tracks, it is introduced making loop track and direct connection track between radiating and circular railways. By these methods, a master plan of improvement of metropolitan electric railways is made and vision of the railways becomes common to passengers.

• 전자공학회논문지B
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• 제30B권5호
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• pp.43-51
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• 1993

A new Hangul code called Truecode is developed for accomodating to the future computing environments of graphical user interface and multimedia as well as for corresponding with the invention principle of Hangul. Truecode is not a forced two-byte code of syllable unit, as completion-type of combination-type, currently used, but a one byte code of phoneme unit, which can represent initial consonant, vowel, and final consonant each. It is quite different from three-byte code of syllable unit and also does not require the fill code used for three-byte code. We expect great contribution to the Hangul culture from Truecode's some important following features. It can express all the Korean characters we may imagine and does not cause any problem in communication. As well as we may use direct connection font, we can assign ont-to-one correspondence between Truecode and a keyboard with three sets. Truecode has a good advantage in developing application softwares of Hangul and it can nicely be applied to the fields of speech recognition and artificial intelligence using natural language.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2015년도 제46회 하계학술대회
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• pp.1102-1103
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• 2015

The researchers worldwide have been trying to apply high temperature superconducting wire for power system devices. High voltage direct current (HVDC) transmission system has been used for bulk and long-distance power transmission. The authors designed a laboratory-scale superconducting DC transmission line to investigate its applicability to an HVDC system. The superconducting DC transmission line was simulated in connection to a laboratory-scale HVDC system using PSCAD/EMTDC. The operating characteristics of the superconducting DC transmission line connected to HVDC system and the effects of the superconducting DC transmission line on HVDC system were analyzed and compared with the results of a conventional DC transmission line. The results of operating characteristics for the superconducting DC transmission line were discussed in detail.

• 대한가정학회지
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• 제31권3호
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• pp.143-155
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• 1993

In recent years, behavioral disorders of young people and juvenile delinquency tend to increase remarkably in number, and closed up highly as a social and educational problems in Korea. It goes without saying that parents generally play important roles in children's development of personality, and the home is mostly responsible for juvenile delinquency. Therefore, first this paper describes a relation between broken family and juvenile delinquents. Burt, Shideler, Neumayer, and Glueck maintain that broken family is a cause of delinquency, on the other hand, Healy and Sutherland assume a critical attitude toward their contentions. Second, Breckinridge, Merril, and Glueck maintain that poor family is as cause of delinquency, while Sullenger, Neumayer, and Dirksen make a considerable point which poverty has no direct connection with delinquency. Third, abnormal family relationships namely, discord family, abnormal parent-child relationship, and immoral family exert a bad influence upon formation of personality, esepecialy during the period of preschool childhood. These results give some empirical support to the theory that children's conduct disorders and juvenile delinquency are caused by defective family relationships. It is necessary that a community has a supporting structure of children's wholesome development and the prevention of juvenile delinquency.

• Asian Pacific Journal of Cancer Prevention
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• 제16권14호
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• pp.6171-6172
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• 2015

A direct connection between certain lifestyle factors and an increased risk of cancer has already been established. Despite well-documented associations, controversial messages on causes of cancer often appear without taking into consideration their impact on the general population. While mainstream coverage of cancer research is clearly welcome, consideration must be given to the risk of transmitting provocative messages with serious negative consequences for cancer research and public health. We must avoid becoming a breeding ground for the misinterpretation of scientific information. Polemical results can stimulate scientific research and progress, but controversial messages encourage confusion and impotence in an increasingly disoriented population. The correct communication of health messages is at least as important as research on risk factors.