• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.36 no.1
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• pp.66-72
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• 2000

In these days, with development of industry, the use of machines and structures like ships, airplanes, bridges, power plants, and structure for construction has increased and these machines and structures are used in various corrosive environment. Especially, in case of STS 304, which is material for every kind of machine and chemical plant, it makes many problems related with corrosion and as a result of this, there are happening tremendous economic loss. Therefor, in this study, the test for polarization characteristics was carried out to study characteristics of crevice corrosion of STS 304 which is austenitic stainless steel, in NaCl environment.The main results obtained are as follows :1) Part of crevice is corroded, neighboring outside surface of crevice is passivation. 2) In polarization behavior, corrosion potential of STS 304 become more noble as the concentration of NaCl solution increased by 3.5% but the concentration increased over 3.5% that of STS 3.4 become less noble. 3) The current density under corrosion potential was high drained as concentration of NaCl solution increased by 3.5% but the concentration increased over 3.5%, the current density was low drained.

• Journal of the Korean Magnetics Society
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• v.14 no.3
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• pp.109-113
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• 2004

GMR isolator was modeled using a Wheatstone bridge which is profitable for transmitting rectangular wave digital data, and the output voltage characteristics in relation to the input current were investigated in time domain. GMR isolator modeling was divided into two parts, namely magnetic and electric parts. The flow chart of the modeling was drawn in which measured MR curve of the spin valves were incorporated to obtain the electrical voltage output. For magnetic modeling, 3-dimensional model of planar coil was analyzed by FEM method to obtain the magnetic field strength corresponding to the input current. For electric modeling, resistance, inductance and capacitance of the planar coil were calculated and magnetic field waveform was obtained corresponding to the coil current waveform in time domain. Finally, MR-H curves of spin valves and the magnetic field waveform at the spin valves were composited to obtain the output voltage waveform of the isolator. Even though the amplitude of the coil current waveform was increased by 100％, decreased by 90％, or delayed by 10％ of the period compared with the input current, similar transmitted output voltage waveform to the input current waveform was obtained due to hysteretic characteristics of the spin valves at the transmission speed of over 400 Mbit/s.

• Journal of the Ergonomics Society of Korea
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• v.33 no.5
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• pp.423-432
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• 2014

Objective and Background: The objective of this study was to evaluate the association of individual characteristics, work-related factors, lifestyle factors, and health problems with work ability among aging workers in Korea. Method: In this cross-sectional survey, the study population consisted of 1,594 workers who had participated in a voluntary health promotion center and private workplace. Participants completed the work ability index. Results: The mean WAI score was 37.4, while the mean age of the sample was 43.25. In the age group over 50 showed 36.26. The majority of participants rated their work ability as 'good' to 'excellent', one-third moderate and about 7.5% poor. Work ability decreased significantly with age among the men. The younger group had higher scores on the work ability index than the age group over 50, except for mental resources. By work characteristics, work ability was analyzed to be the lowest in the case of work handling heavy stuff. Lastly, as a result of health factors analysis, the good management and retention of current health status can be the measure helpful to the improvement of work ability. Conclusion and Application: According to the results, it can be a basic principle to devise and enforce preventive measures on the factors for which improvement or action is possible, together with workplace-level systematic approach, in order to improve work ability. For such measures to be realized, it is necessary to check trends in change for several years.

• Korean Institute of Interior Design Journal
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• v.18 no.4
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• pp.43-50
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• 2009

Design trend, transparency, which has been developed under a reflection of current periodic environment, has been exposed to people all over the world through varieties of architecture facade and interior space. As interior space follows this trend, which has difference in showing space from the past, transparency becomes an important measure of showing openness of certain space. Main objective of this research is to understand a characteristics of materials that leads transparency a important measure to the modern interior design, and this will set the range to this applicable materials for appropriate areas of defining transparency in an interior. Characteristic uses of transparent materials found in this research which leads transparency into interior space are described below: First, there are two perspectives in transparency. One is visibility and material wised transparency and the other is conditional and spacial wised transparency. With this knowledge, we can expand a level of transparency with ideas such as clarity, opacity, visible transmission, and reflection, and this broadened range will vary the acceptable materials used to show transparency. Second, transparent materials are used with many different purposes in modern interior space as furnitures, sanitary fixtures, partitions, and other structures. With using modern technology in reforming this materials brought new methods in structure composing. last, transparent materials' expnt pable characteristics made modern interior space to have a control over spacial homogeneity, a simplified octlines, weakened boundaries, and compositional effects by interference and vision.

• Proceeding of Spring/Autumn Annual Conference of KHA
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• 2006.11a
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• pp.352-356
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• 2006

This study aims to analyze the current status and characteristics of apartment house unit plans towards spatial differentiation. The 172 house units from 32 housing complexes were selected for this analysis. In this study, factors of residential space plan especially in an apartment house are categorized into general characteristics on floor plan and factors for spatial floor plan. The Primary findings are as follows: (1) General characteristics on floor plan are analyzed based on space organization, area and number of bays. Among apartment houses over 40 pyeong, it seems that differentiation is well applied with various space plans available. (2) A result of an analysis on the factors for spatial floor plan shows that planning a living room with two-open-sides seems to be more common in the tower-shaped apartment blocks which are now on the increase. Moreover, many of them are adopting movable partitions to reflect resident's various demands on space plan. Among all, the extra kitchen in the balcony is planned high portion of 80.4%. And diningroom is positioned on the front side of the residential space along with a livingroom(19.2%). More frequently, dining area tends to face the living room(30.2%) according to the result. Besides dress rooms begin to be placed in each of the bedroom, once planned in one bedroom only while 18.6% of the apartment houses are placing new storages in the entrance to solve lack of storage space due to balcony extension.

• Journal of Environmental Health Sciences
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• v.28 no.4
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• pp.12-16
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• 2002

Workers' exposure to lead particles with diverse characteristics was assessed using personal cascade impactors in four different industries. Correlation analyses found that total airborne lead (PbA) concentrations could not explain the variation on MMAD of lead particles. From regression analysis, the concentrations of lead particles smaller than 1 um in AD were found to rise very slowly with increases in total PbA. They rarely contributed more than 50 ㎍/㎥ of total PbA over the range of 5.6-7,740 ㎍/㎥ although there are a few high values greater than 100 ㎍/㎥ while respirable lead concentrations significantly increased with increasing total PbA concentrations. In the secondary smelting and radiator manufacturing industries requiring high temperatures, the average fraction of respirable concentration in total PbA was 43.3% and 48.9%, respectively, which indicated an important contribution to the total PbA. In lead powder and battery manufacturing, it was less than 27%. Our study results concluded that workers' exposure to lead particles with diverse characteristics might not be effectively monitored by the current total PbA sampling alone. To protect workers exposed to different sizes of lead particles generated in many operations, an occupational standard for respirable lead particles should be added to the current total lead standard.

• Korean Journal of Materials Research
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• v.23 no.3
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• pp.177-182
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• 2013

Nanosphere lithography is an inexpensive, simple, high-throughput nanofabrication process. NSL can be done in different ways, such as drop coating, spin coating or by means of tilted evaporation. Nitride-based light-emitting diodes (LEDs) are applied in different places, such as liquid crystal displays and traffic signals. The characteristics of gallium nitride (GaN)-based LEDs can be enhanced by fabricating nanopatterns on the top surface of the LEDs. In this work, we created differently sized (420, 320 and 140 nm) nanopatterns on the upper surfaces of GaN-based LEDs using a modified nanosphere lithography technique. This technique is quite different from conventional NSL. The characterization of the patterned GaN-based LEDs revealed a dependence on the size of the holes in the pattern created on the LED surface. The depths of the patterns were 80 nm as confirmed by AFM. Both the photoluminescence and electroluminescence intensities of the patterned LEDs were found to increase with an increase in the size of holes in the pattern. The light output power of the 420-nm hole-patterned LED was 1.16 times higher than that of a conventional LED. Moreover, the current-voltage characteristics were improved with the fabrication of differently sized patterns over the LED surface using the proposed nanosphere lithography method.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.8
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• pp.638-644
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• 2010

We have carry out numerical simulation of the electric-optical characteristics of organic light emitting diodes with gradient-doped emitting layer which were reported to be effective in improving luminous efficiency and lifetime. In this paper, the basic structure is comprised of ITO/NPB/$Alq_3$:C545T[%]/$Alq_3$/LiF/Al, six devices by separating the emitting layer of $Alq_3$:C545T[%] were studied. As the result, the uniformly-doped devices exhibited superior luminous efficiency-current density characteristics over conventional undoped device. In the case of gradient-doped devices, electric-optical characteristics were improved similar to uniformed-doped devices, unusually the distribution of traped-charge density in the OLED devices was shown as the staircase.

• Proceedings of the KIPE Conference
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• 2007.11a
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• pp.148-150
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• 2007

A novel torque sharing function (TSF) is presented. To improve efficiency and to reduce torque ripple in commutation region, only a phase torque under commutation is regulated to produce a uniform torque. And the torque developed by the other phase remains with the previous state under a current limit of the motor and drive. If the minimum change of a phase torque reference can not satisfy the total reference torque, two-phase changing mode is used. Since a phase torque is constant and the other phase torque is changed at each rotor position, total torque error can be reduced within a phase torque error limit. And the total torque error is dependent on the change of phase torque. To consider non-linear torque characteristics and to suppress a tail current at the end of commutation region, the incoming phase current is changed to torque increasing direction, but the outgoing phase current is changed to torque decreasing direction. So, the torque sharing of the outgoing phase and incoming phase can be smoothly changed with a minimum current cross over. The proposed control scheme is verified by some computer simulations and experimental results.

• Proceedings of the KIEE Conference
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• 2007.10c
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• pp.138-140
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• 2007

A novel non-linear logical torque sharing function (TSF) is presented. To improve efficiency and to reduce torque ripple in commutation region, only a phase torque under commutation is regulated to produce a uniform torque. And the torque developed by the other phase remains with the previous state under a current limit of the motor and drive. If the minimum change of a phase torque reference can not satisfy the total reference torque, two-phase changing mode is used. Since a phase torque is constant and the other phase torque is changed at each rotor position, total torque error can be reduced within a phase torque error limit. And the total torque error is dependent on the change of phase torque. To consider non-linear torque characteristics and to suppress a tail current at the end of commutation region, the incoming phase current is changed to torque increasing direction, but the outgoing phase current is changed to torque decreasing direction. So, the torque sharing of the outgoing phase and incoming phase can be smoothly changed with a minimum current cross over. The proposed control scheme is verified by some computer simulations and experimental results.