• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.774-777
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• 2005

In this paper, a constant frequency phase shifting PWM controlled voltage source full bridge-type series load resonant high-frequency inverter using the IGBT power modules is presented for innovative consumer electromagnetic induction heating applications such as a hot water producer, steamer and super heated steamer. The full bridge arm side link passive quasi-resonant capacitor snubbers in parallel with the each power semiconductor device and high frequency AC load side linked active edge inductive snubber-assisted series load resonant tank soft switching inverter with a constant frequency phase shifted PWM control scheme is discussed and evaluated on the basis of the simulation and experimental results. It is proved from a practical point of view that the series load resonant and edge resonant hybrid high-frequency soft switching PWM inverter topology, what is called class DE type. including the variable-power variable-frequency(VPVF) regulation function can expand zero voltage soft switching commutation range even under low output power setting ranges, which is more suitable and acceptable for induction heated dual packs fluid heater developed newly for consumer power utilizations. Furthermore, even in the lower output power regulation mode of this high-frequency load resonant tank high frequency inverter circuit it is verified that this inverter can achieve ZVS with the aid of the single auxiliary inductor snubber.

• Journal of Environmental Science International
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• v.16 no.3
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• pp.323-331
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• 2007

Polycyclic aromatic hydrocarbons (PAHs) are well known for strong carcinogen. However, the human exposure analysis of PAHs is quite difficult and unreliable because of hard for estimation of actual expose dose. Then urinary 1-hydroxypyrene (1-OHP) has been a biological marker of exposure to PAHs. The purpose of this study was to investigate total amount from exposure to PAHs soused by indoor occupational exposure, and residence at Seoul metropolitan area and Kyeonggi province in Korea. Thirty-five housewives were included in this study from April 2003 through February 2004. Dietary habit and general characteristics such as age, type of building, existence of passive smoking, period of residence, fuel type for heating and ventilation type were obtained by self administered questionnaire. Urine samples were collected at morning and freeze quickly. Urinary creatinine was measured for converting into 24 hr urine. Concentration of the indoor PAHs was examined by NIOSH method number 5506. Urinary 1-OHP and PAHs were analysed by HPLC. Correlation coefficient between urinary 1-OHP levels and pyrene concentration of indoor air was 0.66 and statistically significant(P<0.01). The difference of urinary 1-OHP level due to dietary habits were not significant. Urinary 1-OHP level of Spring, Summer, Autumn, and Winter were $0.21{\pm}0.12,\;0.10{\pm}0.17,\;0.16{\pm}0.12,\;0.17{\pm}0.14{\mu}g/g$ cr, respectively. The arithmetic means of urinary 1-OHP for four season tee $0.16{\pm}0.14 {\mu}g/g$ cr. There was a trend that urinary 1-OHP level of residents who dwelling in apartment were higher compared with detached home, Comparison of 1-OHP level between heating by kerosene and LPG, Much higher gas heating type than kerosene type (P<0.05). This result implies that the urinary 1-OHP can be applied as the PAHs exposure indices.

• Ceramist
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• v.10 no.3
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• pp.48-54
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• 2007

Glass-ceramics transparent above $10\;{\mu}m$ in the infrared, have been synthesized. They are based on germanium and antimony sulphides or selenides associated to alkali halides. They are prepared by heating glass samples at temperatures above the glass transition, as a function of time. Ceramisation can be controlled, so that sub-100 nm crystals are generated in the glass matrix. Then, low light scattering is achieved and the transparency window of the original glass is maintained. When gallium sulphide is added, glass ceramics can be doped with rare-earth ions. Emissions from the $^4F_{3/2}$ and $^4I_{13/2}$ of $Nd^{3+}$ and $Er^{3+}$ ions, respectively, are more intense in glass-ceramics, as compared to their vitreous counterpart. Examination of band profiles and decaytimes show that rare-earth ions are embedded in both crystalline and glassy environments.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2001.05a
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• pp.151-154
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• 2001

Shape memory alloy (SMA) has demonstrated its potentials for various smart structure applications. SMA wires undergo a reversible phase transformation from martensite to austenite as temperature increases. This transformation leads to shape recovery and associated recovery strains. If SMA actuators are embedded off the neutral surface and are oriented in arbitrary angles with respect to a beam axis, then the beam bends and twists due to the coupling effects of recovery strains activated. In this study, the bending and twisting of a SMA/Composite beam were controlled by both electric resistive heating and passive elastic tailoring. 3-dimensional finite element formulations were derived and validated to analyze the responses of the SMA/Composite beam. Numerical results show that the shape of the SMA/Composite beam can be controlled by judicious choices of control temperatures, SMA angles, and elastic tailoring.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.5
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• pp.327-333
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• 2011

In the present work, a new freeze protection method has been proposed for a natural circulation system of solar water heater. Though electrothermal wire is popularly used for the purpose, there are freezing troubles by wire cut-off and shortage of excessive electric power consumption. In the experimental device, hot water in storage tank was used to heat the outlet pipe from the tank if the pipe surface temperature falls lower than a set point. The cold water pipe to the storage tank was installed to directly contact the hot water pipe surface temperature rose by transferred heat.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.6
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• pp.66-72
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• 2012

The main sources of energy consumption in warehouses are MHE(Material Handling Equipment), HVAC(Heating, Ventilating and Air Conditioning) and Lighting. Warehouses in advanced countries raise energy efficiencies with energy consumption diagnosis, technology development and systematic management and improvements for MHE, HVAC and Illuminating, etc. They have managed illuminating system, air conditioning, motor driven system, air circulation method, dock facility, layout, AS/RS, conveyor system and battery management, etc. Ansong Pyeongtaek area investigation resulted that 43.9[%] of enterprises are managing partly energy consumption source. But the data resulted with not substantial management of energy consumption but passive management for only electric bill curtailment. Therefore through survey research & visiting interviews of some companies in Ansong Pyeongtaek area, we understood the status of energy consumption source management and proposed energy efficiency methods on the basis of that results.

• Advances in aircraft and spacecraft science
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• v.1 no.1
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• pp.15-25
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• 2014

The developed concept of smart flow control based on turbulence scale modification was applied to control a flow around a circular cylinder. The concept was realized using arrays of vortex-generators regularly spaced along a cylinder generatrix with a given step. Mechanical and thermal vortex-generators were tested, the latter having been based on the localized surface heating or plasma discharges initiated with microwave radiation near the surface. Thus depending on a particular engineering solution, flow transport properties could be modified in passive or active ways. Matched numerical and experimental investigations showed a possibility to delay flow separation and, accordingly, to improve the aerodynamic performance of blunt bodies.

• Proceedings of the KIEE Conference
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• 2003.07e
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• pp.87-91
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• 2003

Most of the loads in industrial power distribution systems are balanced and connected to three wires power systems. However, in the user power distribution systems, most of the loads are single & three phase and unbalanced, generating a large amount of non-characteristic harmonics. With the advent of power electronics and proliferation of non-linear loads in industrial power applications, power harmonics and their effects on power quality are a topic of concern. Harmonics by the unbalance voltage and non-linear loads, cause the increase of machine loss and heating. In order to allow current harmonic compensation, a filter must be installed. This paper describes the performance of passive filter under the voltage unbalance and non-linear load.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.05a
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• pp.222-223
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• 2018

Recent government policies are increasing interest in zero-energy housing, a building that minimizes energy consumption (90% reduction). As the importance of building passive performance is emphasized, the role of insulation is increasing as a way to reduce indoor heat loss in order to minimize the use of cooling and heating energy. There are two main types of insulation. Organic insulation is widely used for various construction structures such as construction and industrial due to some merits such as the convenience of construction and construction cost. However, it has been pointed out as a main cause every time a fire accident occurs, Jecheon Sports Center', the fire damage of buildings caused by the use of organic insulation materials is expanding to social problems, so it is urgent to research on nonflammable inorganic insulation materials.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.10
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• pp.491-500
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• 2003

Most of the loads in industrial power distribution systems are balanced and connected to three wires power systems. However, in the user power distribution systems, most of the loads are single & three phase and unbalanced, generating a large amount of non-characteristic harmonics. With the advent of power electronics and proliferation of non-linear loads in industrial power applications, power harmonics and their effects on power quality are a topic of concern. Harmonics by the unbalance voltage and non-linear loads, cause the increase of machine loss and heating. In order to allow current harmonic compensation, a filter must be installed. This paper describes the performance of passive filter under the voltage unbalance and non-linear load.