• Maxillofacial Plastic and Reconstructive Surgery
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• v.27 no.6
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• pp.575-580
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• 2005

Transitional implants were developed to support provisional restorations and to allow for load-free osseointegration of conventional implants while a patient was provided with immediate esthetics and function and are usually placed simultaneously at the time of definitive implant placement. Transitional implants are placed in a non-submerged fashion in a single-stage surgery and are designed to be immediately loaded. They generally are made of commercially pure titanium or titanium alloy and are designed as 1-piece implants composed of root and crown replacement segments. Transitional implants can be used in a wide range of indications, such as basic use as temporary implant, to support and protect the primary implants during the healing phase, single crown in the edentulous anterior region of mandibular, anchorage for orthodontic treatment, support a surgical and radiographic template, and primary implant to extremely atrophied alveolar crests of the mandible and maxilla. This article describes the clinical use of transitional implants to support the provisional complete denture and single crown in the restricted edenturous central incisor region of mandible.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.38 no.2
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• pp.138-144
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• 2015

Recent university students are under a lot of stresses due to academic performance, employment, and anxiety about the future in the fierce competition. Mobile games can be used as a plan which can reduce the stresses of these students. However, if they play too long the games, it will cause another big problems. In this paper, we experimented to look for the best mobile game time to alleviate the stresses of university students as follows. First, we chose 16 people which have more stress load than the average student through stress tests by the basic diagnosis questionnaire. Second, we did total eight experiments on the stresses of the subjects in the study. That is, the experiment was carried out once before the test, 6 times for the mobile game (60 minutes), and once before the experiment. Third, we did T-test and multivariate analysis on the collecting data. As a result, it is proved that the mobile game for about 20 minutes could derive the effect on reducing stresses.

• Journal of the Korean Solar Energy Society
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• v.35 no.2
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• pp.85-91
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• 2015

In this study, energy performance analysis of houses in zero energy demonstration town(ZeT) was carried out using the monitoring results. This ZeT was composed 29 zero energy individual houses(ZeH) which were applied passive as well as active technologies. The results are as follows. (1) Residents are generally considered to have been lacking basic mind to save energy, (2) In particular, average yearly total energy consumption per house is 12,834 kWh and specific heating energy is $53.2kWh/m^2{\cdot}yr$ which is higher than that of passive house. This is because of one of the reason just pointed out in subsection (1). (3) Most part of the residual energy load are supplied with only renewable energy, but not operating energy for geothermal heat pump which is use of cheap electricity.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.6
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• pp.1238-1245
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• 1988

Friction and wear characteristics of short fiber reinforced and particulate filled composites were investigated experimentally. Two kinds of fiber composites, chopped graphite fiber reinforced PAI(polyamide-imide) and glass fiber reinforced PAI, and a particulate composite, TiO$_{2}$ powder filled PAI, were selected for the friction and wear test since these are important engineering materials based on a new high temperature engineering plastic. All the specimens were cut into proper size for cylinder-on-plate type wear test. Frictional forces were measured by employing a load transducer and wear rates were calculated by measuring weight loss during wear test. The experimental results are reported in this paper and carefully discussed to explain the friction and wear behavior qualitatively. The frictional behavior is interpreted by considering four basic friction components which are believed to the genesis of friction and the wear behavior is explained by applying delamination theory of wear.

• Progress in Superconductivity and Cryogenics
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• v.20 no.2
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• pp.34-39
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• 2018

A cryogenic cooling system is designed for a 154 kV/ 2 kA three-phase hybrid type superconducting fault current limiter (SFCL). The superconducting modules of the SFCL have the operating condition of 71 K at 500 kPa. The total heat load of the SFCL including the cooling system is estimated at 9.6 kW. The cooling system of the closed loop is configured to meet the operating condition, depending on cooling methods of forced flow cooling and re-liquefaction cooling. The cooling system is composed of three cryostats with superconducting modules, cryocoolers, liquid nitrogen circulation pumps, a subcooler and a pressure builder. The basic cooling concept is to circulate liquid nitrogen between three SFCL cryostats and the cryocooler, while maintaining the operating pressure. The design criterion for the cooling system is based on the operation results of the cooling system for a 154 kV/2 kA single-phase hybrid SFCL. The specifications of system components including the piping system are determined according to the design criterion.

• Journal of the Korea Institute of Building Construction
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• v.13 no.4
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• pp.400-406
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• 2013

In high-rise buildings, high-strength concrete is widely used to reduce the section of structure members under axial load. Also, the price increase of materials is very important item in the high-rise buildings. Especially, concrete used high-pressure pump due to consecutive structural assembly. Unlike slump type of ordinary concrete, high strength concrete has different properties of concrete pumping due to viscosity. However, there have been no Korean studies on the pumping properties of high strength concrete. Therefore, this paper measures the friction factor of high strength concrete with changes in the pressure of concrete pumping. We analyzed the trends of the friction factor based on changes in the pressure of concrete pumping, and then calculated the quantity of concrete deposited for each specified concrete strength and location of placement. After comparing these results with the quantity of concrete deposited measured in field, we evaluated the pumping properties of high strength concrete. Through the tests and the review, we attempt to suggest some basic information for the In-Situ application of high strength concrete.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.9
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• pp.1242-1248
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• 2012

Electric vehicle usage is currently very low, but it will be increase with development of electric vehicle technology and a good government policy. Moreover in 2020, advanced electric vehicle manufacturing system will give high performance for its price and mass production. Electric vehicle will become widespread in Korea. From an operational and a planned viewpoint, the electric power demand should be considered in relation to diffusion of electric vehicles. This paper presents the impact of the various battery charge systems. A comparison is performed for electric vehicle charging methods such as, normal charging, fast charging, and battery swapping. In addition, economic evaluation for the replaceable battery system and the quick battery charging system is performed through basic information about charging Infrastructure installation cost. The results of the evaluation show that replaceable battery system is more economical and reliable in side of electric power demand than quick battery charging system.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.7 no.1
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• pp.30-36
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• 1993

A simple discontinuous conduction mode(DCM) flyback type active power factor corrector for low power supply resents an effective resistive load to its power input. It is therefore well suited as an inexpensive high power factor rectifier for office equipment. An equivalent circuit model for the Active Power Factor Corrector based on the "Loss Free Resistor" concept is presented. This simple model correctly describes the basic power processing properties of the Active Power Factor Corrector, including input port resistor emulation, output port power some characteristics.teristics.

• The Transactions of the Korean Institute of Power Electronics
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• v.10 no.2
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• pp.177-185
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• 2005

A new high efficiency DC/DC converter is proposed, which is derived from the conventional asymmetric half-bridge converter. Because the proposed converter has better ZVS condition compared with the conventional asymmetric half-bridge converter, it shows a high efficiency along the wide load range. In this paper, the basic operations of the proposed converter is analyzed and compared with that of the conventional half-bridge converter, and the excellent performance of the proposed converter is verified by the experimental results with the 425W, 385-170Vdc prototype of the power supply for PDP (Plasma Display Panel) Sustain Driver of PDP TV.

• Journal of the Korea institute for structural maintenance and inspection
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• v.5 no.3
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• pp.181-189
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• 2001

Recently, the need for strengthening reinforced concrete(R.C.) structure has been increased, particularly when there is an increase in load requirements, a change in use, a degradation problem, or design/construction defects. The use of composite materials for structural repair presents several advantages and has been investigated all over the world. It is well known that the incorporation of carbon fiber sheet(CFS) with concrete is one of the most effective ways to strengthen the R.C. structure. In this papers, experimentally investigated the ductile behavior of the R.C. beams strengthened with CFS, and provided the basic data for design of R.C. beams strengthened with CFS. Tests were carried out with 15 beams ($20cm{\times}30cm{\times}240cm$) reinforced with CFS, and with parameters including and the ratio of tensile reinforcement to that of balanced condition and number of CFS. The results show that strengthened and non-strengthened beams exhibit different ductile behovior. Non-strengthened beams showed increase of ductility as amount of the tensile reinforcement decreased. However, bearing capacity of the CFS-strengthened beams are dictated by the strength of the CFS layers that a very high ductility is indicated for the beams with large number of CFS.