• Journal of the Korea Academia-Industrial cooperation Society
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• 제13권8호
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• pp.3345-3351
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• 2012

In this study, simulation of an underwater platform system which is able to perform the underwater test is implemented to predict its dynamic characteristics. Accordingly, its governing equations are derived to construct the mathematical model. From the proposed model, the time in flooding and the pressure of ballast tank in blowing air to come up are predicted. In addition, simulation of the stability of the system for repulsive force of the tube by compressed air is carried out. Their results will be used to select valves, air tanks as well as design the system including ballast tanks. And they will help users operate it efficiently.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 한국조명전기설비학회 2002년도 학술대회논문집
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• pp.257-258
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• 2002

본 논문에서는 200 [W]급 저압 자외선램프용 전자식 안정기를 제작하여 전기적 특성을 측정하였다. 입력전압 220 [V], 구동주파수는 용으로, 안정된 전기적 특성을 갖는 것으로 입증되었다.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 한국조명전기설비학회 2002년도 학술대회논문집
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• pp.259-260
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• 2002

본 논문에서는 250 [W] 고압나트륨램프용 전자식 안정기를 제작하여 전기적 특성을 측정하였다. 개발한 전자식 안정기는 입력전압 220 [V]용으로, 안정된 전기적 특성을 갖는 것으로 입증되었다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2000년도 제1회 학술대회 논문집
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• pp.105-106
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• 2000

The positive slope of the current-voltage characteristic at pressure up to 850 torr was obtained using the closed microhollow cathode without the individual and/or distributed ballast. This indicates that the stable parallel operation of the discharge was also achieved using the closed microhollow cathode. The parallel operation makes it possible to manufacture de plasma displays with high pressure, small discharge current, and long lifetime.

• Journal of the Korean Society for Railway
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• 제11권1호
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• pp.54-60
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• 2008

In the trackbed design using elastic multilayer model, the stress-dependent resilient modulus $(E_R)$ is an important input parameter, that is, reflects substructure performance under repeated traffic loading. However, the evaluation method for resilient modulus using repeated loading triaxial test is not fully developed for practical purpose, because of costly equipment and the significantly fluctuated values depending on the testing equipment and laboratory personnel. The this study, the paper will present an indirect method to estimate the resilient modulus using dynamic properties. The resilient modulus of crushed stone, which is the typical material of sub-ballast, was calculated with the measured dynamic properties and the range of stress level of the sub-ballast, and approximated with the power model combined with bulk and deviatoric stresses. The resilient modulus of coarse grained material decreases with increasing deviatoric stress at a confining pressure, and increases with increasing bulk stress. Sandy soil (SM classified from Unified Soil Classification System) of subgrade was also evaluated and best fitted with the power model of deviatoric stress only.

• Journal of the Korea Institute of Information and Communication Engineering
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• 제7권7호
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• pp.1563-1568
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• 2003

The introduction of invasive marine species of living things into new environments by ship's ballast water, attached to ships' hulls and via other vectors has been identified as one of the four greatest threats to the world's oceans by Global Environment Facility(GEF). Making use of the new technology of alpha-AL$_2$O$_3$ dielectric barrier layer, the strong electric-field gas discharge was introduced and obtained between micro-gap electrodes at high pressure (∼105㎩) of $O_2$ in air and $H_2O$ in seawater. The mixed air with $H_2O$ could be ionized and dissociated into large numbers of activated particles of OH, $O_2$＋, O(1D), HO$_2$ and so on, and then dissolved into the ballast water to form dissolved hydroxyl radical with the concentration of ∼20mg/L. Therefore, the invasive marine species was treated effectively through the hydroxyl radical dissolved pipeline of ballast water by strong electric -field discharge.

• Proceedings of the KSR Conference
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• 한국철도학회 2007년도 춘계학술대회 논문집
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• pp.395-403
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• 2007

Railroad track consists of relatively simple structures such as rail, sleeper, ballast. Roadbed shares vertical pressure by train load which passed through rail to ballast as base that supports the track. For evaluating stress and displacement of roadbed due to the railroad load is an important role on the track as a basic data for estimation of the durability and design of the roadbed thickness. GEOTRACK program applied multi-layered theory was developed for analyzing railroad track structure. GEOTRACK program is a sort of numerical analysis program which has advantage that can analysis component of track by simple method. In this study, this program was used to preform the numerical analysis by changing track conditions and roadbed conditions such as tie, reinforced roadbed, dynamic wheel load, Resilient modulus and so on. Further detail will be presented on the paper.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 한국조명전기설비학회 2003년도 학술대회논문집
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• pp.185-190
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• 2003

The most shortcoming of metalhalide lamps is what the instant restarting cannot be realized when the arc tube is in the hot condition. The discharge starting voltage of arc tube in the hot condition is much higher than in the cold condition. Therefore it takes about five minutes to restart the metalhalide lamps, that is to say, it is possible to start when the pressure and the temperature are decreased. But, if the lamp is restarted in the hot condition, we must supply the high voltage pulse with 20kV at the both sides of lamp. The proposed electronic ballast is consist of a electromagnetic interference (EMI) filter, a power factor correction (PFC) circuit, a flyback converter, a half-bridge inverter, and a high voltage igniter circuit. By this composition we can restart the lamp with the voltage 20kV, even if the lamp is in the hot condition.

• The Transactions of the Korean Institute of Electrical Engineers
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• 제38권6호
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• pp.470-476
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• 1989

In order to develop a mathematical model which can predict the operating voltage and current of a discharge lamp, the properties and the physical phenomena of a low pressure gas discharge are investigated. Fluorescent lamp which uses a low pressure mercury-argon gas discharge is used in the model development. In a low pressure mercur-argon gas discharge, the continuity equation for each excited atom and electron, and the electron energy balance equation can predict the physical quantities of discharge. By coupling these equations and the circuit equation, the electrical characteristics of the discharge lamp can be predicted. To verify the validity of the suggested model, we calculated the voltage and current of a fluorescent lamp operating with inductor ballast for source frequency of 5KHz, 8KHz, 10KHz, and 13KHz. The results show good agreements in wave forms between the measured voltage and current, and the difference between the measured and calculated one is less than 5%.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 한국조명전기설비학회 1992년도 추계학술발표회논문집
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• pp.11-15
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• 1992

Currently-using low-pressure lamps are usually drivel by the AC power supply. There are good and bad points according to high or low frequency in AC power driving type. For the low-pressure lamps, its efficiency increases and flicker decreases when it ignites at high frequency. So we already use the high-frequency electronic ballast of the low-pressure discharge lamps broadly. But there are EMI interference in high-frequency driving type because of giving the fluorescent lamp the high- frequency current. So recently, we have a tendency to compensate for that defects by DC driving method. As follows, we suggest pseudo DC discharging electronic bar lasts for fluorescent lamps which have the characteristics of high efficiency and no flicker by driving constant current boosted square wave.