• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1999.05a
• /
• pp.630-633
• /
• 1999

This paper presents a new sort of multilayer piezoelectric ceramice transformer for switching regulatied power supplies. And this paper presents the study and development of a DC-DC converter with a transformer made from piezoelectric materials. This piezoelectric transformer operate, in the second thickness extensional vibration mode. Its resonant frequency is higher than 1MHz, This piezoelectric transformer was used the PbTiO$_3$ family ceramics because it was a material large anisotropy between electromechanical coupling factors k$_{t}$ and k$_{p}$. The input and output layer consists of two piezoelectric ceramic layer for eleivater of outpur power.wer.

• Proceedings of the KIEE Conference
• /
• 1998.07c
• /
• pp.875-879
• /
• 1998

A fault on the transmission line results in the variation of reactance and parametric uncertainties in the power system dynamics. In this case, we need a robust control to cope with these uncertainties. A sliding mode control, a sort of robust control, is known to be robust to parametric or state-dependent uncertainties if the bounding function of uncertain terms is determined a priori. However, in general, we can not readily determine the bounding function for the complex systems. Hence, in this paper we introduce a fuzzy system which can estimate the bounding function in relatively simple way. By the use of the proposed fuzzy system, determination of bounding function is made easier. We applied the proposed scheme to the stabilization of power system under the sudden fault on the transmission lines. The simulation result verifies the effectiveness of the scheme.

• Proceedings of the KIEE Conference
• /
• 2000.07b
• /
• pp.1065-1067
• /
• 2000

This paper describes performance analysis of ARCP Inverter, which can offer zero voltage switching at nominal voltage stress. The system consists of a voltage-source inverter with sort-switching module. Each main switch is connected in parallel with resonant capacitor and two auxiliary switches are placed in series with a resonant reactor for soft-switching capability. The described ARCP inverter could be effectively applied for active power filter reactive power compensator, and UPS.

• Journal of the Korea Institute of Building Construction
• /
• v.7 no.3
• /
• pp.91-98
• /
• 2007

Recently a construction industry introduces information that brings about many advantages in the early planning phase, design phase and construction phase. Especially it replaces 2D, 3D systems(usually using explanation of drawing information) ai 4D CAD(offering a sort of 4D-having relation of construction schedule and 3D drawing information). Nevertheless a 4D has these benefits, it has limits which are not only usually using 3D modeling but also limit of making full use of practical affairs because of a lack of connecting varietals of progress of work. To solve these uppermost limits, this research is presenting unified systems to use in risk management which are efficient management of space and non-space information, space analysis, making full use of data base, introducing GIS system of easy interaction.

• Journal of the Korean Society of Costume
• /
• v.5
• /
• pp.153-163
• /
• 1981

Since Korea opened the door to the Western World, traditional costume has changed. The factors of change are as follows: 1) Cultural diffusion by the cultural contact is the foundamental factor of the costume change. 2) The government made edicts of clothing reform. The formal dresses of government official were simplified several times, the edict was issued for men to cut off their hair, and military uniform and government officials' dresses were west-ernized. 3) The diffusion of modernized education by the missionary school accerlerated clothing change. Students were ahead of the abolition of Suege-Chima (which is a sort of veil used to conceal woman's face). 4) The change in the activity of women in society made the women's dresses more convenient for action. 5) The open class system and social agitation speeded up the rate of change. During the Yi Dynasty class distinction was rigid, but the government made the laws which abolished the class distiction.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 1999.05a
• /
• pp.256-262
• /
• 1999

By development of heat resistant alloy, there are much improvement of gas turbine engines. But heat resistant alloy has difficulty of machining. therefore, ECM (Electrochemical Machining) is used for Machining of 3 dimensional curved surface of Ni-base alloy. The purpose of this paper is to investigate ECM parameters that make tile good surface for Ni-base alloy blade. For this purpose, we have been investigated that center line average surface roughness(R$\sub$a/), average R$\sub$a/, Maximum R$\sub$a/ and Standard deviation of R$\sub$a/ for measuring positions is influenced on ECM parameters such as electrolyte types, dwell time, electrolyte pressure and sort of electrolyte for Inconel 718 and Waspaloy.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 1996.03a
• /
• pp.108-113
• /
• 1996

Conventionally, grinding of stainless steel, aluminium alloy, copper alloy, and titanum alloy is difficult due to the mechanical properties such as low hardness, high toughness which result in the loading of wheel and the poor surface finish. In order to grind this sort of materials easily, discontinuous grinding wheel with multi-porous grooves was newly developed. The multi-porous grooves were formed during wheel production. This discontinuous grinding wheel drastically increases the grinding performance. It is desirable to use the discontinuous grinding wheel when grinding materials with high efficiency and accuracy which is impossible by conventional wheels. In this paper, the construction and manufacturing method of grinding wheel with multi-porous grooves are explained. The grinding charateristics of discontinuous grinding wheel was also illustrated.

• Journal of Fisheries and Marine Sciences Education
• /
• v.27 no.3
• /
• pp.682-695
• /
• 2015

The purpose of this study was to identify subjective perception types on anger expression among female nursing students and to investigate characteristics according to the subjective perception types. In order to achieve this purpose, the study used Q-methodology. There were 30 study participants and they completed the Q-sort activity, rating each statement relative to the others using 32 Q statements. The data were analyzed using the QUANL PC program. There were three types of forms extracted from anger expressions among female nursing students; a type on 'embracive soothing', a type on 'reasonable expression', and a type on 'ambivalence over emotional expression'. The commonality of the three types were: talking about their anger emotions with others, asking for help in religion and pushing their opponent. Therefore, Adequate strategies based on anger expression types need to be developed to resolve anger among female nursing students.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.33 no.1
• /
• pp.10-16
• /
• 2010

Mail centers are essential postal facilities that sort and dispatch postal items, and should be operated efficiently to provide customers high quality postal services. So the efficiency analysis of mail centers should be performed in order to induce better operation. But current performance evaluation system has 95 percent of predetermined and weighted non-quantitative indices. There is need to introduce objective efficiency measurement methodology. The main objectives of this study was to analyze the efficiency of 24 mail centers empirically using cone-ratio DEA and suggest the appropriate cone-ratio method. Consequently, this paper suggests that the cone-ratio DEA model integrating decision-maker's preferences is more desirable for efficiency analysis than that of using transformed data.

• Journal of Korean Academy of Nursing
• /
• v.33 no.4
• /
• pp.519-528
• /
• 2003

Background. In Seoul, Korea, 70% of all adult males are reported to be smokers, and guidelines to smoking cessation generally include ways to help smokers avoid situations of smoking temptation. However the phenomenon of smoking temptation has been scarcely studied. Therefore, it is critical to acquire a better under-standing of smoking temptation for more effective nursing practice. Aim. This study intends to analyze the subjectivity of smoking temptation. Design. Q-methodology, which applies a scientific method to subjectivity, was utilized. Findings. Five distinct smoking temptation modalities, on Q-types, emerged from the Q-sort: 1) Urge to facilitate interpersonal relation; 2) Psychological desire for tranquility; 3) Habituation in social life; 4) Habituation in daily life; and, 5) Nicotine craving combined with daily routine. Conclusion. It is hoped that analysis of the five types of smoking temptation identified in this study will contribute to the body of knowledge and a better understanding of why smokers are addicted to smoking.