• Journal of the Korean Institute of Telematics and Electronics
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• v.9 no.2
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• pp.36-44
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• 1972

• Korean Journal of Optics and Photonics
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• v.14 no.3
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• pp.292-297
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• 2003

A diode-pumped single-mode Nd:YV $O_4$ green laser was developed. Frequency doubling of the laser was achieved by using an intracavity KTP generated green beam (532 nm). By comparing the diode laser spectrum with absorption spectrum of the Nd:YV $O_4$ crystal, we found optimal operating temperature of the diode laser. From output power measured for various mirror curvatures and cavity lengths, we found the optimal matching of TE $M_{00}$ mode with the pump beam gives the best efficiency. When the pump power was 1.9 W, 80 ㎽ of TE $M_{00}$ mode green beam was obtained. We tried to get a single longitudinal mode lasing as the fluctuation of the laser power was caused by the shift of longitudinal modes and the beating between the modes. We tested the intracavity etalon method and birefringent filter method for single mode operation. The etalon method resulted in the best single mode output power of 60 ㎽. The power fluctuation of the single-mode laser was reduced to 1/10 of that of the multi-mode laser.

• Proceedings of the KIPE Conference
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• 2013.07a
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• pp.397-398
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• 2013

Fairchild Green Mode off line buck switch for low standby power consumption and high reliability is presented. By reducing operating current and optimizing switching frequency, 20mW power consumption is achieved. High performance trans-conductance amplifier and green mode function improve the ripple and regulation in the output voltage. The conventional $FPS^{TM}$ buck and novel Fairchild buck switch are compared to show the improvement of performance. Experimental results are showed using 2W evaluation board.

• Current Optics and Photonics
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• v.3 no.1
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• pp.22-26
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• 2019

A compact red-green-blue beam combiner (multiplexer) based on two-mode interference (TMI) is proposed and its feasibility is shown through three-dimensional beam propagation simulation. The first stage TMI beam combiner makes red (637 nm) and blue (446 nm) beams combined toward one output port and the second stage one combines red, blue, and green (532 nm) beams. The power transmission to the output port from the red, green, and blue input ports are 0.96, 0.99, and 0.98, respectively. When the wavelength deviation is 10 nm, the transmission is maintained to be larger than 0.9. The size of the combiner is as tiny as $0.02{\times}3.8mm^2$.

• Transactions of the Korean hydrogen and new energy society
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• v.22 no.6
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• pp.852-858
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• 2011

This paper is aiming to estimate the mutual influence of the stack cooling performances with the operation modes of the thermal management system for the hydrogen fuel cell vehicles. The heat capacity of the thermal management system was measured by varying the operating modes such as stack cooling heat exchanger only (Mode 1), stack cooling and electric devices cooling heat exchangers (Mode 2), and stack cooling and electric devices cooling heat exchangers with an operation of the condenser (Mode 3).As the results, Performance of the thermal management system (TMS) at Mode 3 decreased up to 34.0%, compared with the result of the Mode 1. In addition, in order to optimize the performance of TMS, the entropy change of stack cooling heat exchanger using irreversibility analysis technique was analyzed with the relationship between entropy generation and entering air velocity of the thermal management system.

• THE INTERNATIONAL COMMERCE & LAW REVIEW
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• v.55
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• pp.265-290
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• 2012

CEPA (Comprehensive Economic Partnership Agreement) between India and Korea may vitalize Korean economy more and more. Currently most of Korean firms have entered into manufacturing industries like electronics and automobiles. But only a few Korean companies are trying to penetrate into Indian green industry so this paper suggest how to enter into Indian green industry, especially renewable energy sectors. First, Exporting main shaft, tower-flange and polysilicon products can be considered, as a first step of entry mode. Second, entry mode based on contract like technology licensing, strategic alliance and joint venture establishment can be also one of options. For example, Korean solar energy industry which show more competitiveness than that of Indians should try to make technological licensing on PV modules. In addition to this, they should also try to make joint ventures with right Indian partners and build up 'Solar City' nearby regions like Gurgaon in India where many Korean firms are located. Korean shipbuilding firms like Hyundai Engineering which keep on developing wind turbo engines can also try to make strategic alliance with Indian firms like Suzlon which has strong competitiveness. After that, they should explore Korean and Indian wind sector markets together. Third, brownfield investment can be last and final option as a entry mode as we consider the peculiar characteristics of renewable energy industry. Lastly, Korean government which are rush to indulge into green business should formulate more proper and realistic policies to give big incentives the concerned firms which are trying to open international green market so government should make Korean green firms not to lose good market opportunities related to green industry like renewable energy sectors. Renewable energy sectors are basically regarded as infrastructures so close contact to Indian central government as well as state government will be also required.

• Journal of IKEEE
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• v.14 no.2
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• pp.1-8
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• 2010

In this paper, Green Mode Power IC is designed to reduce the standby power. The proposed and designed IC works for the Switch Mode Power Supply(SMPS) and has the function of PWM. To reduce the unnecessary electric power, burst mode and skip mode section are introduced and controlled by external power MOSFET to diminish the standby power. The proposed IC is designed and simulated by KEC 30V-High Voltage 0.5um CMOS Process. The structure of proposed IC is composed of voltage regulator circuit, voltage reference circuit, UVLO(Under Voltage Lock out) circuit, Ibias circuit, green circuit, PWM circuit, OSC circuit, protection circuit, control circuit, and level & driver circuit. Measuring the current consumption of each block from the simulation results, 1.2942 mA of the summing consumption current from each block is calculated and ot proved that it is within the our design target of 1.3 mA. The current consumption of the proposed IC in this paper is less than a half of conventional ICs, and power consumption is reduced to the extent of 1W in standby mode. From the above results, we know that efficiency of proposed IC is superior to the previous IC.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.2
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• pp.191-198
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• 2011

In this paper, a method to approximate a multi-layer Green's function is proposed based on a FDTD scheme and a rational function approximation. For a given horizontal propagation wavenumber, time domain response is calculated and then Fourier transformed to the spectral domain Green's function. Using the rational function approximation, the pole and residue of the Green's function can be estimated, which are crucial for a calculation of a path loss. The proposed method can provide a wideband Green's function, while the conventional normal mode method can be applied to a single frequency problem. To validate the proposed method, We consider two problems, one of which has a analytical solution. The other is about multi-layer case, for which the proposed method is compared with the known normal mode solution, Kraken.

• Geomechanics and Engineering
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• v.20 no.1
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• pp.9-18
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• 2020

Three-point bending specimens have been used to investigate the mixed mode fracture of green sandstone. Dimensionless stress intensity factors and T-stresses were calculated first by using the finite element method for various crack lengths, crack angles and span to length ratios. It is shown that three-point bending specimens can provide the whole range of mode mixities from pure mode I to pure mode II, provided suitable values are chosen for the crack angle and span to length ratio. The fracture test results were also used to compare with predictions of different criteria. These comparisons show that modified criteria including the influence of the T-stress agree better with experiment than the conventional criteria but that no one criterion matches perfectly the test results.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.2B
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• pp.111-119
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• 2011

As Green-IT has attracted a lot of attention in recent years, many researches have been interested in reducing the energy consumption of network equipments. In this paper, we analyze the energy saving ratio and delay performance according to various traffic patterns and burst assemble algorithms in OBS network with sleeping mode. To do this, we design the traffic generators, which are based on exponential distribution and Pareto distribution, and the router model, which has the time based and length based burst assemble algorithms by using OPNET modeler. Through OPNET simulator, we evaluate the energy saving performance in terms of the sleeping time, the number of transitions and packet delay.