• The Transactions of the Korean Institute of Electrical Engineers B
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• v.54 no.12
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• pp.601-608
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• 2005

This paper presents a novel single-stage high-power-factor electronic ballast for fluorescent lamps operating in critical conduction mode. The proposed topology is based on integration of boost converter as power factor corrector(PFC) and a half-bridge high frequency parallel resonant inverter into a single stage. The input stage of the boost converter is operating in critical conduction mode for positive and negative half cycle voltage respectively at line frequency(60Hz). So that a boost converter makes the line current follow naturally the sinusoidal line voltage waveform. The simulated and experimental results for 100W fluorescent lamps operating at 42kHz switching frequency and 220V line voltage have been obtained. This proposed inverter will be able to be practically used as a power supply in various fields as induction heating applications, fluorescent lamp and DC-DC converter etc.

• Journal of Environmental Science International
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• v.23 no.7
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• pp.1367-1373
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• 2014

This study was conducted to evaluate the effects of heating hatching eggs on the number of day-old chicks, egg temperature and egg weight during extended storage, and to provide basic information for improving hatchability to livestock producers. Eggs (Hy-line) were subjected to the following treatments: "control": eggs were maintained in an incubator after storage for 8 days; "T1": eggs were preheated for 8 hours at $23.9^{\circ}C$ after storage for 8 days in a hatchery; "T2": eggs were initially heated for 8 hours at $37.8^{\circ}C$ in an incubator and then preheated for 8 hours at $23.9^{\circ}C$ in a hatchery after storage for 8 days. The results were as follows: First, at the end of the experiment, the total number of day-old chicks was higher in T1, followed by T2 and then the control. This indicated that chick hatchability may be improved when eggs are preheated. Second, compared with the control, the number of day-old female chicks was expected to be higher in treatments with pre-heating; however, the results indicated the opposite effect. Third, as storage time lengthened, the factor that influenced preheating (the main effect and interactions) was not egg weight but egg temperature measured in the upper, middle and bottom parts of incubator. The temperatures recorded in all treatments ranged from 37.97 to $38.40^{\circ}C$ in the upper parts of incubator, 37.80 to $38.26^{\circ}C$ in the middle parts of incubator, and 37.94 to $38.59^{\circ}C$ in the bottom parts of incubator over storage. In conclusion, preheating was very effective in improving hatchability, and egg temperature was the main factor affecting preheating and hatchability.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.21 no.1
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• pp.27-34
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• 2015

Heating patterns depending on the packaging materials were examined in order to investigate the causes of thermal deformation of packages used for ready-to-eat foods for microwave heating due to the non-uniformity of microwaves. Physical properties including tensile strength, heat-resistance and elongation of four different CPP grades were compared. High retortable CPP had higher sealing strength and heat resistance compared to the conventional CPPs. All CPP samples tested were proved to have melting temperatures around $160^{\circ}C$. However, they were all thermally deformed by microwave heating due to a limited penetration of microwave and non-uniform heating within the spicy sauce of high viscosity contained high salt, especially on the above the filling line and sealing edge of pouches. When the laminated stand-up pouches composed of G-PET/PET/PET/CPP and G-PET/PET/NY/CPP were retorted and microwaved, significant deformations were noticed in both samples after retorting. Besides, pouches contained titanium dioxide showed more intense thermal deformation than the control. When the $10{\mu}m$ aluminium foil was affixed on the pouch, small thermal deformation was observed only in the bottom layer. More studies are required to prevent the thermal deformation of packaging materials used for RTE foods during microwave heating by developing the technologies to increase the thermal stability of CPP layer and the modification of packaging design to modify the microwave access into the package.

• Proceedings of the KWS Conference
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• 2008.05a
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• pp.25-25
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• 2008

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1995.05a
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• pp.78-81
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• 1995

In the present study, the spray column type of direct contact heat exchangers are studied experimentally to analyze heat transfer characteristics for solar energy utilization. These experiments are carried out in the line of solar heating system, major results are as follows ; 1) the flow and aspect of working fluid drop for maxium heat transfer 2) efficiency and volumetric heat transfer coefficient of D. C. H. X. with a heavier working fluid are higher than those of D. C. H. X. with a lighter working fluid

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.70.2-70
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• 2001

This paper presents an application model for home automation control. In this work, we propose home application scenarios that are suitable for the home life style and design a control structure integrating various home automation functions, such as lightning, heating, cooling, security, fire protection, telemetering, entertainment and communication. State-of-the-art wired/wireless home networks such as Bluetooth, LonWorks, IEEE1394 and PLC(Power Line Communication) are included in the control structure.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.61.3-61.3
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• 2017

We have studied the high-resolution $H{\alpha}$ and Ca II $8542{\AA}$ line profiles of Ellerman Bombs (EBs) obtained with the Fast Imaging Solar Spectrograph (FISS) installed on the 1.6m Goode Solar Telescope (GST) in Big Bear Solar Observatory (BBSO). The FISS spectra of EBs are compared with synthetic profiles computed using RH non-LTE radiative transfer code and a set of 1D atmospheric models with local transient heating, the latter of which is modeled by varying local temperature enhancement in magnitude and height. We could reproduce each of the observed $H{\alpha}$ and Ca II line profiles separately with different atmospheric models, but not with a single atmospheric model. To fit the observed $H{\alpha}$ lines we often need much higher temperature enhancements than those needed for fitting Ca II lines. Possible causes for this temperature mismatch are briefly discussed.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.08a
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• pp.119-125
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• 2004

Radiant tube heaters are widely used for indirect heating in heat treatment processes such as continuous annealing line(CAL) or continuous galvanizing line(CGL). Main issues for radiant tube are temperature uniformity, lifetime, thermal efficiency. To achieve higher heat release, the radiant tubes are fired at a higher fuel rate and therefore local overheating occur. A numerical simulation based on a commercial code FLUENT has been performed to investigate local overheating of radiant tube heaters. To minimize local overheating, the effects of radiating fins, flue gas recirculation(FGR), two-stage combustion were investigated. More uniform temperature distribution was achieved in the longitudinal direction within the tube with radiating fins and this contributed to increase the life of radiant tubes. Furthermore, the radiant tube with radiating fins was proven to be more efficient than the one without fins. The effects of flue gas recirculation and two stage combustion on the efficiency of the radiant tube were also considered and the results were presented.

• Journal of Electrical Engineering and Technology
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• v.9 no.1
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• pp.254-258
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• 2014

This paper presents the performance analysis results of a short line fault interruption of a gas circuit breaker, particularly a self-blast type breaker. Hot gas flow analysis was carried out using a CFD calculation combined with the arc model and nozzle ablation model. To evaluate the interruption performance, the index function was defined using the pressure in the heating chamber and the density above the arc region. The simulation and test results showed that the gas flow field and suitable choice of an interruption performance index can be used to predict the interruption characteristics and provide guidelines for designing self-blast breakers with a higher interruption capability.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.6
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• pp.686-692
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• 2012

Solid free-form fabrication (SFF) technology was developed to fabricate three-dimensional (3D) scaffolds for tissue engineering (TE) applications. In this study, we developed a polymer deposition system (PDS) and created 3D microstructures using a bioresorbable polycaprolactone (PCL) polymer. Fabrication of 3D scaffolds by PDS requires a combination of several devices, including a heating system, dispenser, and motion controller. The system can process a polymer with extremely high precision by using a 200 ${\mu}m$ nozzle. Based on scanning electron microscope (SEM) images, both the line width and the piled line height were fine and uniform. Several 3D micro-structures, including the ANU pattern (a pattern named after Andong National University), $45^{\circ}$ pattern square, frame, cylindrical, triangular, cross-shaped, and hexagon, have been fabricated using the polymer deposition system.