• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.2
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• pp.177-182
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• 2000

Composite insulation system of liquid nitrogen and solid spacer is widely applied in high temperature superconduction power machine. This study has three step procedure. As follow, first step is composition of parallel deposited electrode and vertically deposited electrode along the direction of immersion in liquid nitrogen(LN2). Second step is investigation into surface flashover voltage of solid spacer under partially immersed in LN2, and last step is comparison the result of this research with that of fully immersed in LN2 and at cryogenic temperature gaseous nitrogen(GN2). This result presented that surface flashover voltage along solid spacer half immersed in LN2 was almost the same as that of fully immersed spacer when the thickness of spacer(t) was t<10mm. In the case of t> 10mm, however, spacer flashover voltage was equal to that obtained in GN2 at cryogenic temperature. And the immersed direction functions as role of deciding the difference of surface flashover voltage.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.3
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• pp.384-389
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• 2003

A new two-step soft-output Viterbi algorithm (SOVA) decoder architecture is presented. A significant reduction in the decoding latency can be achieved through the use of the dual-port RAM in the survivor memory structure of the trace-back unit. The system complexity can be lowered due to the determination of the absolute value of the path metric differences inside the add-compare-select (ACS) unit. The proposed SOVA architecture was verified successfully by the functional simulation of Verilog HDL modeling and the FPGA prototyping. The SOVA decoder achieves a data rate very close to that of the conventional Viterbi Algorithm (VA) decoder and the resource consumption of the realized SOVA decoder is only one and a half times larger than that of the conventional VA decoder.

• Textile Coloration and Finishing
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• v.16 no.5
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• pp.1-7
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• 2004

Because acid dyes and reactive dyes require acidic condition for adsorption and alkaline condition for fixation respectively, it is difficult to dye nylon/cotton blends in one-bath one-step dyeing method. In this paper we tried to find out the suitable dye and dyeing condition for one-bath one-step dyeing of nylon/cotton blends. MNT type reactive dyes showed higher exhaustion on cotton as compared with MCT type dyes at neutral pH, which means that the MNT type reactive dyes are preferable for one-bath one-step dyeing method. The optimum condition for one-bath one-step dyeing of nylon/cotton blends was found to be pH 7. Wash fastness of fabrics dyed with half-milling type acid dyes was superior to that of fabrics dyed with levelling type acid dyes, when MNT type reactive dyes were used together.

• KIEE International Transactions on Electrophysics and Applications
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• v.4C no.5
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• pp.193-200
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• 2004

In this study, we propose a small high voltage power supply, which uses a half-bridge ZCS resonant and Cockroft-Walton circuit as its ESP (Electrostatic Precipitator). This power supply transfers energy from the ZCS resonant inverter to the step-up transformer. The transformer secondary is then applied to the Cockroft-Walton circuit for generating high voltage as a discharging source of electrodes. It is highly efficient because its amount of switching losses are reduced by virtue of the current resonant half-bridge inverter, and also due to the small size, low parasitic capacitance in the transformer stage owing to the low number of winding turns of the step up transformer secondary combined with the Cockroft-Walton circuit. Using this power supply, experiments have been carried out as a function of the switching frequency and duty ratio in order to investigate the smoke removal characteristics. From these results, the best operational condition is obtained at the switching frequency of 9 kHz and the duty ratio of 50% in this ESP.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.7
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• pp.1055-1061
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• 2002

This paper deals with a design and fabrication of an electronic ballast for 70[W] ceramic discharge metal halide lamps. The proposed ballast is composed of a rectifier, an active power factor correction circuit (PFC), a half-bridge inverter, a LC resonant circuit and a microprocessor. The developed ballast also includes a specially designed time circuit which provides reignition signal of lamps. Running frequency of the ballast is .jet at 40[kHz] to avoid acoustic-resonance and flickering. From the experimental results, input power factor and efficiency of the ballast are estimated 99.8[%] and 93.1[%], respectively.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.5
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• pp.49-56
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• 2006

The bi-directional converter interfaces the low voltage battery to the inverter do link of FC generation system. When power flows from the low voltage side(battery: 48[V]) to the high voltage side(dc link: 380[V]), the circuit works in discharge mode (boost) to power the high voltage side load; otherwise, it works in charge mode (buck) to charge the low voltage side battery. In this paper, the 1.5[kW] active clamp current-fed full bridge converter employing MOSFETs is operated to discharge the battery whereas a voltage-fed half bridge converter employing IGBTs is operated to charge the battery.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.11
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• pp.635-644
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• 2002

Many generating units can be in parallel connection to one battery and inverter. However, one of the biggest problems we encountered is that wind speed is fluctuated sharply in accordance with the unstable weather conditions. To solve this problem, we need energy storage equipment such as storage lead-acid battery. We design a system and analyze its modeling so that it supplies a stable power to the load through DC-AC inverter part. In this paper, we applied dual step-up/down buck-boost converter and dual high-frequency half-bridge converter to the proposed system. These converters are used to store energy in the battery regardless of the change of the wind speed. The operation process of two proposed types of converters for high-power battery charging is discussed along with simulation and experimental result. We design a charging circuit which is applicable in the actual wind power generation system for 30kw and confirm the circuit's validity.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.11a
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• pp.435-439
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• 2002

This paper describes a design and fabrication of an electronic ballast for 70[W] ceramic discharge metal halide lamps. The proposed ballast is composed of a rectifier, an active power factor correction circuit (PFC), a half-bridge inverter, a LC resonant circuit and a microprocessor. The developed ballast also includes a specially designed time circuit which provides reignition of lamps. Running frequency of the ballast is set at 40[kHz] to avoid acoustic-resonance and flickering. From the experimental results, input power factor and efficiency of the ballast are estimated 99.8[%] and 93.1[%)] respectively.

• Journal of the Microelectronics and Packaging Society
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• v.16 no.1
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• pp.39-43
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• 2009

In order to develop piezoelectric inverter module for CCFL driving, Rosen-type multilayer piezoelectric transformer was fabricated. The output power and efficiency of mutilayer piezoelectric transformer according to the variation inner electrode layer were investigated. Mutilayer piezoelectric transformer was fabricated conventional mutilayer ceramic method using PZT base ceramics. Also, piezoelectric inverter module was adopted driving circuit with half-bridge type. The piezoelectric inverter module was set up with input voltage 12.5 V, switching frequency 104.3 KHz. The results showed the value of step-up ratio 100, efficiency 87% at load resistance of $100k{\Omega}$.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.32 no.2
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• pp.146-152
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• 2022

Objectives: The purpose of this study is to confirm whether there is a factor to affect the evaluation of fit test of a 2nd class half masks using a OPC test method. Methods: Total 34 adults including Males and Females were tested using OPC-based fit testing equipment while wearing a 2nd class half filtered mask. Results: 1. The result of measuring face dimensions using different tools such as a 3D scanner and digital calipers revealed that the variation of lip width was not statistically significant because there was only a difference of about 4 mm. However, it showed that a difference in face length was statistically significant enough with 10 mm(p<0.000). 2. The fit factor for each exercise stage according to gender was the highest at 124.54(p<0.001) in Step 3, and the fit factor was the lowest at 73.75 in Step 1. 3. In the evaluation of the degree of fit factor according to gender, female passed 67.44%, which was higher than the value in male(p<0.038). 4. The acceptance rate of the group having a face length of shorter than 110 mm was 91.67%. On the other hand, the acceptance rate of the group with a face length of longer than 110 mm was 47.27%(p<0.000). 5. The fit test was possible because the fit factor with 2nd class half masks corresponding to FFP1(Filtering Face Piece 1) was passed 55% or more. Conclusions: The test results showed that using a 2nd class half filtered mask, it is important to wear a properly designed mask so that face size does not affect the fit factor.