• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.1921-1923
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• 2004

V-p characteristics and the discharge luminous characteristics in inhomogeneous $SF_6$ gas gap under the positive and negative lightning impulse voltages are presented. The test gap was composed of the plane-to-plane with a needle-shaped protrusion. The applied voltage and the predischarge current were measured by the electric field sensor and the shunt of 50 ${\Omega}$, respectively. The light emission signals were observed by a photomultiplier tube, and a high-speed camera. In a consequence, the dielectric strengths of $SF_6$ gas gap under positive lightning impulse voltages were independent of the gas pressure. In the presence of the positive polarity, the branches of discharge channel were created and the directions of the discharge paths were random. On the other hands, the discharge paths of the negative polarity were more thicker and brighter.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2006.05a
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• pp.101-106
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• 2006

네온변압기는 전기 제품의 일종이며, 사용 시간의 경과와 더불어 환경 조건 등 여러 가지 요인으로 서서히 그 성능이 열화하고 마침내 수명에 이르는 성질을 가지고 있다. 최근에는 에너지 절약용, 자원 절약용 등 환경 보호 입장에서 고효율화가 도모되고 있고, 내구성 증가, 소음 저감, 환경에의 적합 등 여러 가지 요구가 높아지고 있으나 확립된 수명 평가 이론은 정립되고 있지 않는 실정이다. 따라서 여기에서는 변압기의 수명 등을 평가할 수 있는 가속시험 방법에 대해서 논하기로 한다.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2008.05a
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• pp.301-304
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• 2008

This paper presents the experimental results on breakdown characteristics in $N_2$ gas under non-uniform electric fields caused by both the positive and negative lightning impulse voltages. $N_2$ gas have an advantage of eco-friendly and cost reduction, and safety aspects. In order to analyze the impulse pre-breakdown processes in $N_2$ gas, we carried out measurements and observations of the impulse breakdown voltages, pre-breakdown current and luminous signals. They were measured by a voltage divider, a shunt and a photo-multiplier tube, respectively. Additionally, the characteristics of discharge channels were observed by high speed cameras. The breakdown voltages in the positive polarity was lower than those in the negative polarity.

• Proceedings of the KIEE Conference
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• 2004.11a
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• pp.129-132
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• 2004

This paper presents an experimental study on the prebreakdown characteristics in $SF_6/N_2$ mixtures under non-uniform electric fields when subjected to the positive and negative lightning impulse voltages. $SF_6/N_2$ mixtures have a merit of an environmental aspect and cost reduction, and safty aspects. In order to analyze the prebreakdown processes in $SF_6/N_2$ mixtures stressed by impulse voltages, prebreakdown current and light were observed by a shunt with high sensitivity and a photo-multiplier tube, respectively. Additionally, characteristics of luminous events in flashovers were discussed.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.4
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• pp.107-113
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• 2008

We investigated the electro-optical characteristics of an ICP(Inductively Coupled Plasma) light source depending on driving temperature, and length of discharge tube. An electro-optical stability of a sample at operating was measured to see a steady state of a sample. In this results, we can see that a stability of power loss and luminous flux of a sample at operating of upper 70[min] was 1.45[%1 and 0.36[%]. We measured the optical characteristics of a sample in a thermal chamber operated at a specific temperature divided into 5 steps. While luminance increased with temperature increasing, the decrement of luminance a eared at u or $46.7[^{\circ}C]$. According to Parchen's and Boyle-Charles' law, we can speculate that a pressure was increased and a higher voltage was needed but a ballaster having a rating power can't support a higher voltage corresponding to a pressure change, 0.02[Torr] at $46.7[^{\circ}C]$. Moreover, we measured an a lied power and current of samples depending to a various length of a discharge tube.

• Journal of Energy Engineering
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• v.18 no.4
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• pp.239-246
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• 2009

A fundamental investigation has been conducted on the combustion of single particle of a sub-bituminous coal char burning at different temperatures and residence times. The lab-scale test setup consisted of a drop tube furnace where gas temperatures varied from $900^{\circ}C$ to $1400^{\circ}C$. A calibrated two color pyrometer, mounted on the top of the furnace, provided temperature profiles of luminous particle during a char oxidation. An amount of char mass reacted during the reaction is measured with thermogravimetry analyzer by using an ash tracer method. As a result, mass and area reactivity as well as reaction rate coefficients are determined for the char burning at atmospheric pressure condition.

• Journal of Radiation Protection and Research
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• v.43 no.4
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• pp.160-169
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• 2018

Background: This study aims to develop an integrated optical system that can simultaneously or selectively measure the signals obtained from radioluminescence (RL), thermoluminescence (TL), and optically stimulated luminescence (OSL), which are luminescence phenomena of materials stimulated by radioactivity, heat, and light, respectively. The luminescence mechanism of various materials could be investigated using the glow curves of the luminescence materials. Materials and Methods: RL/TL/OSL integrated measuring system was equipped with a X-ray tube (50 kV, $200{\mu}A$) as an ionizing radiation source to irradiate the sample. The sample substrate was used as a heating source and was also designed to optically stimulate the sample material using various light sources, such as high luminous blue light emitting diode (LED) or laser. The system measured the luminescence intensity versus the amount of irradiation/stimulation on the sample for the purpose of measuring RL, TL and OSL sequentially or by selectively combining them. Optical filters were combined to minimize the interference of the stimulation light in the OSL signal. A long-pass filter (420 nm) was used for 470 nm LED, an ultraviolet-pass filter (260-390 nm) was used for detecting the luminescence of the sample by PM tube. Results and Discussion: The reliability of the system was evaluated using the RL/OSL characteristics of $Al_2O_3:C$ and the RL/TL characteristics of LiF:Mg,Cu,Si, which were used as dosimetry materials. The RL/OSL characteristics of $Al_2O_3:C$ showed relatively linear dose-response characteristics. The glow curve of LiF:Mg,Cu,Si also showed typical RL/OSL characteristics. Conclusion: The reliability of the proposed system was verified by sequentially measuring the RL characteristics of radiation as well as the TL and OSL characteristics by concurrent thermal and optical stimulations. In this study, we developed an integrated measurement system that measures the glow curves of RL/TL/OSL using universal USB-DAQs and the control program.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.43 no.2 s.308
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• pp.33-39
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• 2006

This paper designed the electronic circuit part of Potable Infrared Night Vision Scope for a small size, light weight, and low power. Designed electronic circuit part is composed of an Auto Voltage Selecting Module, and a Power Supply Module. An Auto Voltage Selecting Modulo is composed of a switch, a battery, a step up voltage part, and a selecting voltage part. A Power Supply Module is composed of a high luminous sensing part, a battery voltage sensing part, a infrared illumination part, a connection sensing part, and a power control part. And this module controls the power of Image Intensifier Tube. To verify the performance of the designed electronic circuit part, we experimented the consumption power and continuous using time. Experimental results show that the designed electronic circuit part improves considerably on the performance of the AN/PVS-14. performance.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2005.05a
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• pp.57-60
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• 2005

This paper describes the experimental results of the pre-breakdown phenomena in $SF_6/CO_2$ mixtures under non-uniform electric fields caused by positive and negative lightning negative voltages. $SF_6/CO_2$ mixtures have an advantage of an environmental aspect and cost reduction, and safety aspects. In order to analyze the pre-breakdown processes in $SF_6/CO_2$ mixtures stressed by impulse voltages, pre-breakdown current and luminous signals were measured by a shunt and a photo-multiplier tube, respectively. Dielectric strengthes of $SF_6/CO_2$ mixtures were investigated. Additionally, characteristics of discharge channels were observed by high speed cameras and the physical properties were discussed. The pre-breakdown propagates with a stepwise process. The in to breakdown from the corona onset point in positive polarity was shorter than that in negative polarity. The time intervals of positive leaders are shorter than those of negative leaders, and the path of positive leader channel is zigzag.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2008.10a
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• pp.93-96
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• 2008

If a fluorescent lamp be used too much time, the filmy part of electronic emission in the lane that is attached near the tube of the cathode brings about blacking. Luminance output and luminous efficiency are decreased. So, it's necessary to replace it. if the user doesn't replace the lamp for a long time, it causes overvoltage in the lamp. Therefore, the filament might be overheated. Even the socket of the lamp might catch on fire. In this paper gives development model of the fluorescent lighting equipment which has ramp shift timely display device.