• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2009.04a
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• pp.65-73
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• 2009

The terrestrial laser scanner measures the signal delay time of electronic circuit in EDM(Electronic Distance Measurement) Module for distance measurement. To measure signal delay time precisely, transmitting laser beam of terrestrial laser scanner is divided optically. Therefore, 10% of the laser beam power is entered into the electronic circuit and the others go out through lens. But, measure of delay time is severe in the laser scanner system that the laser beam power is changed dynamically by reflectance of a object, because characters like gain of electronic circuit involving APD(Avalanche Photo Diode) and so on are changed by incident laser beam. Therefore, we adapt ND(Neutral Density) filter that has grid pattern to the laser scanner system to keep constant the incident laser beam power. In this paper, we propose the simulation program for efficient design of ND filter pattern. Finally, to affirm simulation program, we conduct the experimental test of simulated ND filter that has linearly transmittance change, and we consider the experiment result.

• Journal of Surface Science and Engineering
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• v.32 no.6
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• pp.658-664
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• 1999

Helicon sources are attractive for plasma processing because they provide high plasma density in low magnetic fields. Helicon waves were excited by a Nagoya type III antenna in a magnetized plasma column. Plasma parameters were measured with a double probe, and the structure and adsorption of the helicon wave fields were determined with the probes. Argon is fed through a MFC (mass flow controller) for operation pressure of 10~110 mtorr. A 13.56 MHz r.f. power of 50~450 W is induced through the antenna. The plasma density and electron temperature are measured as functions of external magnetic field, r.f. power and pressure. The plasma density as functions of r.f. power and magnetic field at a constant pressure increased linearly, and the electron temperature did not change largely with various operation parameters and the value was around 5~7 eV.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.1034-1036
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• 2006

In this paper, I used microprocessor and sensor and designed to improve the efficiency of the photovoltaic system the photovoltaic position tracker device, and compared the normal photovoltaic system of fixed form with the photovoltaic system of solar position tracked form. Moreover, compared the catalogue of solar cell module and the simulation through a mathematics modelling with the solar cell's characteristic interpreting and, composed an power conversion system with boost converter and voltage source inverter. Used the constant voltage control method for maximum power point tracking in boost converter control and, used the SPWM(Sinusoidal Pulse Width Modulation) control method in inverter control.

• Journal of Power System Engineering
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• v.8 no.1
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• pp.36-40
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• 2004

Two-phase loop systems using the latent heat capacity of their working fluids can meet the increasing power requirements and are well suited to thermal management systems of future large applications, due to its abilities to handle large heat loads and to provide them at uniform temperatures regardless of the changes in the heat loads. Therefore some experiments on the effect of the gas and liquid superficial velocities, $j_G,\;j_L$ on flow pattern transition, void fraction and frictional pressure loss were performed on a co-current air-water flow in an adiabatic horizontal tube. The flow patterns were depended on the superficial velocity of each phase. It snowed that the increasing $j_L$, resulted in a significant increase in the frictional pressure loss for all flow patterns, at a constant $j_G$. The experimental results were also evaluated with some of existing models and correlations.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.2
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• pp.79-83
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• 2016

This research was analyzed thermal characteristics that was appointed disadvantage when smart LED driver ICs was packaged and we applied extracted thermal characteristics for optimal layout design. We confirmed reliability of smart LED driver ICs package without additional heat sink. If the package is not heat sink, we are possible to minimize package. For extracting thermal loss due to overshoot current, we increased driver current by two and three times. As a result of experiment, we obtained 22 mW and 49.5 mW thermal loss. And we obtained optimal data of 350 mA driver current. It is important to distance between power MOSFET and driver ICs. If thhe distance was increased, the temperature of package was decreased. And so we obtained optimal data of 3.7 mm distance between power MOSFET and driver ICs. Finally, we fabricated real package and we analyzed the electrical characteristics. We obtained constant 35 V output voltage and 80% efficiency.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.165-166
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• 2006

By using a ceramic material with dielectric constant 37, the miniature waveguide ceramic bandpass filter was implemented. The proposed waveguide ceramic bandpass filte was based on the mode matching method and simulation process. For overcoming high power, We used the connector at in/output of waveguide ceramic bandpass filte. The result of power test satisfied the 30W. The product will used as a parts of repeater for wibroband.

• Journal of Industrial Technology
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• v.32 no.A
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• pp.109-114
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• 2012

In this paper, We studied LED(Light Emitted Diode) sensor lights system using PIR(Pyroelectric Infrared Ray) sensor, CdS and MCU(Micro Controller Unit). And applied the valley fill circuit to improve the power factor. We designed the amplifier for each sensor and the LED driver for constant current which is the buck converter. Also, we proposed the algorithm of LED control by each sensors using MCU. Experimental results showed that power factor is 92% with valley fill circuit.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.3
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• pp.382-387
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• 2016

This paper deals with the assessment of voltage sags regarding the variation of system operating conditions. In general, voltage sag assessment is performed by assuming the constant operating condition throughout the year. However, the assumption can lead to assessment errors in case of considerable changes of system operation condition. This paper presents a method to estimate ESF(expected sag frequency) considering the operating conditions according to the changes of power demand throughout the year.

• Proceedings of the KIPE Conference
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• 2013.07a
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• pp.347-349
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• 2013

This paper describes analysis and calculation of line frequency ripple current according to output capacitor value and effects of LED connection in the single stage flyback converter with high power factor. The low frequency output ripple current delivered from single stage converter has been analyzed in detail and the method evaluating parasitic resistance included in LED has been provided. In order to verify the equation derived in this paper, the single stage flyback converter has been designed with constant output current regulation with DCM operation. Experiments were conducted with different LED load structures to analyze the effect of LED parasitic resistance on output ripple current. As test results, the calculation can provide guide line to select capacitor values depending on output ripple current and LED characteristics.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1963-1965
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• 2000

This paper deals with a problem of detecting the inner corrosion of the ACSR(Aluminum Conductor Steel Reinforced) power lines using a detector which consists of an ECT(Eddy Current Test) sensor, a constant current service, a signal processing unit, and a RF transmitter/receiver unit. The detector runs on the ACSR transmission line and inspects the corrosion of the conductor using the technic of the nondestructive eddy current test. The experimental result shows this detector can efficiently find the zinc loss in ACSR power lines.