• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.9
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• pp.1107-1115
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• 2012

This paper presents the development processes of a microwave radiometer for remote sensing of water surface temperature. Achieving the measurement accuracy within $2^{\circ}C$ for water surface temperature of $5{\sim}30^{\circ}C$, the requirements and specifications of the microwave radiometer and its receiver are drawn. The receiver with high gain, high sensitivity is designed and implemented. The receiver has the bandwidth of 50 MHz, the system gain of 45.2 dB and the sensitivity of 0.56K at 5.02 GHz. The effectiveness of the developed microwave radiometer in the measurement of water surface temperature is demonstrated experimentally. The results show the microwave radiometer can detect water surface temperature for $7.5{\sim}18^{\circ}C$ within the accuracy of $0.45^{\circ}C$.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.05a
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• pp.529-534
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• 2002

It was recommended for all ship engaged in international voyages to carry the dedicated Digital Selective Calling receiver, DSC equipment, VHF transceiver, etc according to Global Maritime Distress & Safety System. Also International Maritime Organization recommended for navigation and communication equipments to applicate the EMC regulations, therefore most of electronic equipments using in the vessel to be faced with problems to cope with new regulations. This study has applied and analyzed the EMC for an equipment integrated with Ch.70 dedicated DSC receiver, DSC equipment, VHF transceiver and groped for solutions to cope with. The test has applied the electromagnetic interference such as the measurement for unwanted emissions from conductive & radio emission and the electromagnetic susceptibility such as the immunity from voltage, frequency variation and electro static discharge, hence comes to be understand the problems related with the power and the earth.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.294-299
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• 2004

An assessment of a novel laser-electric hybrid propulsion system was conducted, in which a laser-induced plasma was induced through laser beam irradiation onto a solid target and accelerated by electrical means instead of direct acceleration only by using a laser beam. A fundamental study of newly developed rectangular laser-assisted pulsed-plasma thruster (PPT) was conducted. On discharge characteristics and thrust performances with increased peak current compared to our previous study to increase effects of electromagnetic forces on plasma acceleration. Maximum peak current increased for our early study by increasing electromagnetic effects in a laser assisted PPT. At 8.65 J discharge energy, the maximum current reached about 8000 A. Plasma behaviors emitted from a thruster in various cases were observed with an ICCD camera. It was shown that the plasma behaviors were almost identical between low and high voltage cases in initial several hundred nanoseconds, however, plasma emission with longer duration was observed in higher voltage cases. Canted current sheet structures were also observed in the higher voltage cases using a larger capacitor. With a newly developed torsion-balance type thrust stand, thrust performances of laser assisted PPT could be estimated. The impulse bit and specific impulse linearly increased. On the other hand, coupling coefficient and the thrust efficiency did not increase linearly. The coupling coefficient decreased with energy showing maximum value (20.8 ？Nsec/J) at 0 J, or in a pure laser ablation cases. Thrust efficiency first decreased with energy from 0 to 1.4 J and then increased linearly with energy from 1.4 J to 8.6 J. At 8.65 J operation, impulse bit of 38.1 ？Nsec, specific impulse of 3791 sec, thrust efficiency of 8 %, and coupling coefficient of 4.3 ？Nsec/J were obtained.

• Journal of IKEEE
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• v.23 no.1
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• pp.289-294
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• 2019

At present, domestic small islands mainly supply electric power using diesel generators. However, diesel generators can cause instability of the power system due to slow response on power load fluctuation, and cause environmental problems due to the emission of carbon gas by using fossil fuels. In order to overcome this problem, this paper proposes a method to establish an optimal microgrid by introducing solar power, wind power, and energy storage device to Chujado Island, which is supplied with electric power through a diesel generator. The economical optimum capacity of each distributed power source is calculated by using HOMER (Hybrid Optimization Model for Multiple Energy Resources) program and the proposed microgrid is validated by using PSCAD/EMTDC (Power Systems Computer Aided Design/ Electromagnetic Transients including DC) program which can analyze system stability.

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.2
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• pp.123-134
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• 2012

A typical cooling system of an engine relies on a water pump that circulates the coolant through the system. The pump is typically driven by the crankshaft through a mechanical link with engine starting. In order to reduce the friction and warm-up time of an engine, the clutch-type water pump (CWP) was applied in 2.0 liter diesel vehicle. The clutch-type water pump can force cooling water to supply into an engine by the operation of an electromagnetic clutch equipped as the inner part of pump system. The onset of CWP is decided by temperature of cooling water and engine oil. And, the control logic for an optimal operation of the clutch-type water pump was developed and applied in engine and vehicle tests. In this study, the warm-up time was measured with the conventional water pump and clutch-type water pump in engine tests. And the emission and the fuel consumption were evaluated under NEDC mode in vehicle tests. Also, tests were carried out for the various temperature conditions starting the operation of CWP. From the results of the study, the application of CWP can improve the fuel consumption and $CO_2$ reduction by about 3%.

• Journal of Biosystems Engineering
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• v.39 no.1
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• pp.21-33
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• 2014

Background: Significant technological development and changes happened in the tractor industries. Contrariwise, the test procedures of the major standard development organizations (SDO's) remained unchanged or with a little modification over the years, demanding new tractor test standards or improvement of existing ones for tractor performance, safety, and comfort. Purpose: This study focuses on reviewing the research trends regarding performance, safety and comfort evaluation of agricultural tractors. Based on this review, few recommendations were proposed to revise or improve the current test standards. Review: Tractor power take-off power test using the DC electric dynamometer reduced human error in the testing process and increased the accuracy of the test results. GPS signals were used to determine acceleration and converted into torque. High capacity double extended octagonal ring dynamometer has been designed to measure drawbar forces. Numerical optimization methodology has been used to design three-point hitch. Numerous technologies, driving strategies, and transmission characteristics are being considered for reducing emissions of gaseous and particulate pollutants. Engine emission control technology standards need to be revised to meet the exhaust regulations for agricultural tractors. Finite Element Analysis (FEA) program has been used to design Roll-Over Protective Structures (ROPS). Program and methodology has been presented for testing tractor brake systems. Whole-body vibration emission levels have been found to be very dependent upon the nature of field operation performed, and the test track techniques required development/adaptation to improve their suitability during standardized assessment. Emphasizes should be given to improve visibility and thermal environment inside the cab for tractor operator. Tractors need to be evaluated under electromagnetic compatibility test conditions due to large growing of electronic devices. Research trends reviewed in this paper can be considered for possible revision or improvement of tractor performance, safety, and comfort test standards.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.392-392
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• 2011

Carbon nanotubes (CNT) emitter has widely become an attractive mechanism that draws growing interests for cold cathode field emission.$^{1,2}$ CNT yarns have demonstrated its potential as excellent field emitters.$^3$ Extensive simulations were carried out in designing a CNT yarn-based cathode assembly. The focal spot size dependence on the anode surface of the geometric parameters such as axial distance of the electrostatic focus lens from the cathode and the applied bias voltages at the cathode, grid mesh and electrostatic focus lens were studied. The detailed computer simulations using Opera 3D electromagnetic software$^4$ had revealed that a remarkable size of focal spot under a focusing lens triode type set-up design was achieved. The result of this optimization simulation would then be applied for the construction of the CNT yarn based micro-focus x-ray tube with its field emission characteristics evaluated.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.2
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• pp.31.3-31.3
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• 2018

On August 17th 2017, for the first time in the history, the gravitational wave (GW) detectors recorded signals coming from the merger of two neutron stars. This event was named as GW170817, and more interestingly, gamma-ray emission was detected 2 seconds after the gravitational wave signal, and 11 hours later, telescopes in Chile identified that the GW signal came from the NGC 4993 galaxy at the distance of about 40 Mpc. This is again the first time that electromagnetic (EM) signals are detected for a GW source. The follow-up observations by astronomers all around the world, including our group in Korea, successfully identified the optical emission as the kilonova, the elusive optical/NIR counterpart that has been proposed to originate from a neutron star merger. This whole event started the new era of astronomy, so-called the "multi-messenger astronomy", where the combined information from GW and EM radiation reveals an unprecedented view of the universe. In this talk, I summarize this exciting event, and describe the efforts by Korean astronomers that have led to important discoveries about the kilonova and the host galaxy properties, and finally provide the future prospects.

• Journal of Advanced Navigation Technology
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• v.22 no.2
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• pp.105-110
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• 2018

The North Korea nuclear issue is now posing a serious security threat to the Korea and Northeast Asia. Accordingly, the South Korean military is pushing for the introduction of long-range air-to-surface flights and the development of domestic nuclear facilities that can precisely hit North Korea headquarters building and nuclear facility even hundreds of kilometers above the border. In this paper, we removed the cable braid for securing the weight of the missile among several design elements for long-range air-to-surface missile development and estimated and analyzed the resulting performance. The possibility of braid removal was analyzed in terms of crosstalk inside the cable and CS114, RE101 of MIL-STD-461F.

• Current Optics and Photonics
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• v.5 no.1
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• pp.1-7
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• 2021

For higher sensitivity in ultraviolet (UV) and even vacuum ultraviolet (VUV) detection of silicon-based sensors, a sandwich-structured film sensor based on Ag Localized Surface Plasmon Resonance (LSPR) was designed and fabricated. This film sensor was composed of a Ag nanoparticles (NPs) layer, SiO2 buffer and fluorescence layer by physical vapour deposition and thermal annealing. By tuning the annealing temperature and adding the SiO2 layer, the resonance absorption wavelength of Ag NPs matched with the emission wavelength of the fluorescence layer. Due to the strong plasmon resonance coupling and electromagnetic field formed on the surface of Ag NPs, the radiative recombination rate of the luminescent materials and the number of fluorescent molecules in the excited state increased. Therefore, the fluorescent emission intensity of the sandwich-structured film sensor was 1.10-1.58 times at 120-200 nm and 2.17-2.93 times at 240-360 nm that of the single-layer film sensor. A feasible method is provided for improving the detection performance of UV and VUV detectors.