• 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.

• Fire Science and Engineering
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• v.27 no.3
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• pp.80-84
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• 2013

In modern society, buildings has become larger, more complex and high-rise by the influences of locational and environmental characteristics from the changes of human lifestyles. Such features of the buildings, however, make building management and maintenance more difficult, especially in the aspects of health, security, and safety, etc. In order to secure safety and comfort in dwelling, housing, and working condition, it is essential to establish systematic plans and practices. Thus with the aim of investigating general status of fire safety management on specific buildings, this study mainly analyzed fire prevention manager's awareness on their works by conducting a survey, and suggested required systematic improvements for efficient fire safety management. As a result of the survey, it is concluded that introducing the system to appoint fire prevention sub-managers will promote more professional and classified management conditions.

• International Journal of Highway Engineering
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• v.14 no.1
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• pp.25-34
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• 2012

The rapid economic development induced the massive road constructions, becoming bigger and high-speed of the vehicles. However, it brings lots of social problems, such as air pollutions, traffic noise and vibration. Special concrete block for the base course of asphalt pavement is needed to decrease traffic noise such as tire's explosive and vehicles sound, applying Helmholtz Resonators theory to asphalt pavement. If it is applied to the area where it happens considerable noise such as a junction, the street of a housing complex and a residential street, it is one of alternative methods to solve the social requirements of noise problems. This research examines couple of laboratory tests for the sound absorption effect of the concrete block and the base concrete block for quiet pavement. The specimens, which is fixed hall-size, space, depth as the condition of this research, are analysed of noise reduction effect using different noise levels of vehicles. Judging from the analysis of test results with vehicle noise volume, measurement distance, a form and size of the hall using the base concrete block, the use of special concrete base and quiet asphalt surface showed a good alternative solution for decreasing traffic noise level, from 4dB to 9dB.

• Journal of Korean Society of Rural Planning
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• v.19 no.1
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• pp.23-32
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• 2013

In the traditional subsistence farming era in Korea, most of small farmer's housing plots in the rural villages had their boundary barriers of which materials being the natural ones provided from nearby places. However, during the rapid industrialization period from 1960s, a traditional type of boundary barriers in the rural villages had been replaced mostly by low-cost factory-made ones, which means absolute loss of their amenity values as a linear part of villagescape. In spite of many study efforts on boundary barriers of traditional rural houses, detailed historical dating on them after 1960s have not tried up to now, which provoked to try this study. Through the direct and in-depth interviews to rural villagers sampled from 21 case villages, it was found that original boundary barriers structure in most of farm houses was made of natural materials like stone, soil, trees and bamboo, but, replaced by cement block structures mostly during Saemaeul Project period. However, although being relatively minority, traditional ones have been preserved up to now mainly in remote mountainous and seashore villages, but was in very low condition. In the overall view, for more than half a century, boundary barriers of farm houses had been left without public or private improvement efforts. In order to enhance their amenity values, more research works should be carried out on positive reassessment of the traditional ones harmonized with multifunctionalities for modern village life.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.9
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• pp.789-794
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• 2014

The FPGA is used to the high speed digital satellite communication on the Digital Signal Process Unit of the next generation GEO communication satellite. The high capacity FPGA has the high power dissipation and it is difficult to satisfy the derating requirement of temperature. This matter is the major factor to degrade the equipment life and reliability. The thermal control at the equipment level has been worked through thermal conduction in the space environment. The FPGA of CCGA or BGA package type was mounted on printed circuit board, but the PCB has low efficient to the thermal control. For the FPGA heat dissipation, the heat sink was applied between part lid and housing of equipment and the performance of heat sink was confirmed via thermal vacuum test under the condition of space qualification level. The FPGA of high power dissipation has been difficult to apply for space application, but FPGA with heat sink could be used to space application with the derating temperature margin.

• Proceeding of Spring/Autumn Annual Conference of KHA
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• 2008.04a
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• pp.421-426
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• 2008

In case of the large-scaled indoor gymnasium that has been constructed in the local area, there are many instances for the use as multipurpose space where the public performances are possible such as leisure activity, lecture, assembling activity, drama, concert and so on for the resident together with the purpose of sporting facility. In order for utilization to the maximum of the function of such indoor gymnasium, the acoustic capabilities concerned with Definition of both Voice and Music are simultaneously required. However, in case of the large-scaled athletic facility, since it was designed with high ceiling-height in view of its characteristics, it forms a Sound Focus and then the sound is concentrating to the specific part, and because the vibration of sound is too loud due to its broad volume, the acoustic defects such as many Echoes are arising. On such viewpoint, based on the drawing of the indoor gymnasium that is scheduled to be built at B County, Chonbuk Province, this Study has proposed such indoor gymnasium equipped with the optimized acoustic condition passing through Acoustic Simulation Phase. As the result of Acoustic Simulation, we could design the indoor gymnasium that equipped with really satisfying acoustic performance 'after' reformation compared with 'before' reformation, and it is considering that such material could be utilized as the fundamental material that brings a curtailment effect of the construction cost and also enables us to improve the acoustic performance, at the stage of planning and designing for the similar sporting facility in the future.

• KIEAE Journal
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• v.11 no.3
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• pp.63-68
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• 2011

Building deterioration would be proceeded by various causes such as physical, social, economic degradation. The deterioration would be inevitably prevented or delayed to get the decent function and performance in various building part and components. The maintenance and management are continued to provide the decent living condition for the household. The maintenance means mainly a repair, including the on-time and longterm plan. The longterm repair would be conducted by the systemic preparation in management activity and a required cost. Therefore, the annual due for the longterm repair plan is important to prepare the repair cost in a required time. In this paper, it aimed at analyzing the longterm repair cost and modelling to forecast the required cost in total area, number of household and time elapse in apartment housing. The estimation model of a repair cost is used with a power function which has a good statistics. Results of this study are shown that the sample has a longterm repair due in a $2,032won/m^2{\cdot}yr$ averagely which is higher than $912won/m^2{\cdot}yr$ in domestic. Second, the longterm repair due is proportionally correlated with the time elapse in both a total area and the number of household. Third, the estimation model for the longterm repair amount is suitable for the power function which is most in any other estimation models. Fourth, the ration of the longterm plan repair due a year to the cumulated longterm amount is about 26%.

• Journal of Korean Society on Water Environment
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• v.24 no.1
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• pp.86-90
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• 2008

Water reuse of effluent is limited, due to bacteria and chromaticity or turbidity which may result in low perception of water quality. Consequently, this study showed a method in the reuse of treated wastewater by a diversified treatment method, with separation of centralized reformation of aeration tank into pre-treatment with minimum installation of facilities, and post-treatment, applying advanced oxidation treatment. A pilot plant experiment was performed using Sym-Bio process adopting an NADH Sensor without modification of the exiting aeration tank. The Dissolved Ozone Flotation process, which is an advanced oxidation process, to treat the remaining organics, nutrients, chromaticity, turbidity and bacteria. As a result in the Sym-Bio process, the biological treatment, even on the condition of single stage reaction tank, the treatment efficiencies of BOD, $COD_{Mn}$, $COD_{Cr}$, SS and T-N were 96.6%, 84.6%, 88.25%, 95.1% and 71.0%, respectively, while that for T-P was 25.0%, which required further treatment. In the Dissolved Ozone Flotation process, the advanced oxidation treatment, the treatment efficiencies of BOD, $COD_{Mn}$, $COD_{Cr}$, SS, T-N, T-P, chromaticity, turbidity, bacteria, coliforms were 78.9%, 34.6%, 28.7%, 48.0%, 70.4%, 82.4%, 84.0%, 74.5%, 99.8% and 99.4%, respectively.

• Journal of the Korea Safety Management & Science
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• v.20 no.1
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• pp.11-21
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• 2018

Safety accidents, which are called industrial accidents in construction work, are often caused by unstable physical and personal conditions combined during preparation and execution of work. It is difficult to manage all the construction works, but especially in the field of apartment construction work, complex and many kinds of works are being carried out at the same time. In the current construction, safety regulations such as safety management guidelines are generally well maintained, but the execution of manpower resources that can fulfill them is limited, and it is difficult to reduce the accident rate and loss cost. Therefore, in this study, it is a reality that most of the types of construction work are under contruction by subcontracting contract, so they are limit by methods of manual maintenance and safety education. Currently, the subcontractor is also allowed to perform safety management through the composition of the safety management review body, but it is operated formally. So alternatives to this were studied. As a result, safety accidents occur in the subcontractor's worker due to vertical integration, which is characteristic of the construction industry, together to the contractor, the safety management system is based on a safety construction system in which a worker who has a certain qualification condition such as career experience of the work type, work understanding of the work type, and management experience of the work type among the subcontractor, when we manage based on mutual personality which is the personality of interpersonal relationship that can communicate with each other by work type, process and grouping, it is concluded that effective and practical safety management can be achieved to reduce the accident rate and loss cost.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2007.11a
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• pp.353-357
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• 2007

The Apartment resident's make-up of a family and residing preference are diversified by the change of lifestyle through the elevation of economy level and residing level. Accordingly, the remodeling and the early rebuilding for the satisfaction of a life cycle and a life style are increasing, and "Variability" that is the concept of Open Housing was emphasized as a central of residing plan in the apartment. Although apartments which select the space variability to the residing space are increasing gradually, the optimum composition structural system with space variability that satisfies the structure stability, the economical efficiency and the resident usability is not developed. The method of a study was progressed by a comparison and an analysis on each system with estimation elements through analyzing the development process and the special quality of existing composition structural system with space variability in the apartment. This paper offered the improvement direction on the current composition structural system with space variability for the development of modularizing system that is correct in domestic real condition.