• Journal of the Korean Institute of Telematics and Electronics
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• v.18 no.4
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• pp.49-61
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• 1981

A generally applicable computer simulation program for diffused silicon solar cells has been developed on the basis of the experimental results. The program can be easily used to obtain the spectral response and I-V characteristics for N+P, P+N N+PP+, P+NN+cells by changing various input parameters. The insolated spectra can be taken from AMI and constant intensity and GE - ELH lamp light sources. The options for AR coating are Si3N4 film and materials with constant reflectance including zero reflectance for ideal case. The computer simulation demonstrates successful results compared with the measured values for the short circuit current, open circuit voltage, efficiency, spectral response, quantum efficiency, I-V characteristics, etc. This program was used to optimize doping concentration, cell thickness, light concentration, junction depth, and to obtain the limit values for front surface recornbination velocity, effective carrier life time in the depletion regions and shunt resistance, and also to drive the changing rate in conversion efficiency depending on operation temperature, series resistance and electric field strength in N+P+ bulk regions.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.8
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• pp.582-594
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• 2016

Most studies on hybrid buses are on large-sized buses and not mid-sized low-floor buses. This study uses MATLAB simulation to evaluate the fuel efficiency of such buses powered by diesel. Based on the results, a hybrid electric vehicle system is recommended for the best combination of power and gear ratio. A parallel hybrid system was selected for the hybridization, which transmits front and rear wheel power independently. The necessary power to satisfy the target performance was calculated, and the applicable capacity area was designed. Dynamic programing was used to create and optimize a component sizing algorithm, which was used to scale the capacity of each component of the power source to satisfy the design criteria. The fuel efficiency rate, optimum power source capacity, and gear ratio can be improved by converting a conventional bus into a parallel hybrid bus.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.1055-1057
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• 2002

산업이 발전할수록 정밀 위치제어 알고리즘에 대한 요구가 증가하고 있으며, 선형 전동기의 보급에 따라 1um 단위의 고급 위치 제어 알고리즘에 대한 중요성이 커지고 있다. 위치제어에 있어서 작업의 신속성 및 정밀도를 높이기 위해서는 제어의 오버슛 현상을 억제할 필요가 있으며, 현장에서 직접 활용이 가능하도록 하려면 보다 간단한 구조의 제어 알고리즘이 요구된다. 위치제어에서 가장 큰 문제는 전동기의 최대 속도 및 최대 전류 제한에 의한 비선형성이 위치의 과도한 오버슛으로 나타난다는 것이며, 기존의 고급 알고리즘에서는 미리 제공되는 S-커브 형태의 위치 명령 패턴을 사용하여 속도 및 전류 제한을 회피하고 있다. 본 연구에서는 고급 제어 알고리즘과 동일한 성능을 내면서 복잡한 패턴 생성기를 사용하지 않고도 실제 위치가 오버슛없이 부드러운 S-커브 형태로 목표값에 수렴하는 새로운 형태의 위치제어기를 제안한다. 제안된 제어기는 비교적 간단한 구조로 인하여 헌장 적용력이 매우 뛰어나며, 이득 설정이 간편하다는 장점을 지니고 있다.

• Korean Journal of Optics and Photonics
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• v.20 no.5
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• pp.261-265
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• 2009

Our amplifier using an all optical method and a fixed GFF achieved automatic gain flatness throughput the C-band without any NF degradation, and simultaneously achieved a constant 25 dB gain, while input signals were varied between one channel and forty WDM channels. When thirty nine channels were added and dropped, the transient gain variation of the survival channel was not greater than the steady-state gain variation, and its wavelength dependency was negligible.

• The KIPS Transactions:PartB
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• v.12B no.6 s.102
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• pp.637-646
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• 2005

Most of the multimedia contents for DBM services art provided as MPEG-2 bit streams. However, they have to be transcoded to H.264 bit streams for practical services because the standard video codec for DMB is H.264. The existing transcoder architecture is Cascaded Pixel-Domain Transcoding Architecture, which consists of the MPEG-2 dacoding phase and the H.264 encoding phase. This architecture can be easily implemented using MPEG-2 decoder and H.264 encoder without source modifying. However. It has disadvantages in transcoding time and DCT-mismatch problem. In this paper, we propose two kinds of transcoder architecture, DCT-OPEN and DCT-CLOSED, to complement the CPDT architecture. Although DCT-OPEN has lower PSNR than CPDT due to drift problem, it is efficient for real-time transcoding. On the contrary, the DCT-CLOSED architecture has the advantage of PSNR over CPDT at the cost of transcoding time.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.11
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• pp.1248-1258
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• 2010

In this paper, a method for simultaneously realizing the sum and difference patterns which are required in the monopulse radar sensor systems, is presented by using single taper array antenna with rectangular microstrip patches. The widths of patches are first determined by the voltage weights which are synthesized for the fundamental array factor patterns to be applied to the monopulse operation by using the sidelobe levels(SLLs) control technique. As the bi-directionally series-fed technique is applied and the lengths of connecting lines between patches are appropriately adjusted, the single array generates two phase-shifted beams which activates out-of-phase and in-phase ports of a $180^{\circ}$ hybrid coupler to synthesize the sum and difference patterns. The simulated results on the configuration designed at 9.5 GHz are compared with measured results showing the validity of the proposed method.

• The Transactions of the Korean Institute of Power Electronics
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• v.14 no.6
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• pp.514-521
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• 2009

This paper deals with a new overvoltage snubber for a diode-clamped 3-level IGBT inverter. Usually most power converters use snubber circuits to protect the switching devices from voltage spike. However, it is difficult for the diode-clamped multi-level converter to be protected from voltage spike with overvoltage snubber since the series connection of the switching devices. To solve the problem the characteristic of a overvoltage snubber for a DC-DC converter is analyzed, and a new snubber for a diode clamped 3-level inverter is proposed. The performance of the proposed snubber is verified through experiments.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.2
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• pp.163-169
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• 2016

In this paper, we miniaturized the loop and coil in magnetic resonance wireless power transfer(MR-WPT) system for application to the small mobile device. The proposed disk type double coil resonator was designed to cause resonance at 6.87 MHz. It is composed of thin copper on both-side of acrylic substrate structured 2 mm width, 1 mm pitch and 8 turns. The outer radius of spiral coil pattern is 9 cm. And the proposed loop was made of the copper wire 5 mm diameter of cross-section. The size of loop is 10 cm diameter. For resonance at 6.87 MHz, the capacitor with 3,300 pF was connected in series on the loop. We rearranged the resonators and organized several WPT systems which is rearranged by resonators. The highest transfer efficiency of miniaturized WPT system was 35.67 %. This proposed design of spiral double coil will contribute to make resonator smaller for appling small and thin mobile device.

• Journal of Convergence for Information Technology
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• v.11 no.11
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• pp.166-171
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• 2021

An active mount is devised in same geometric constraints with a conventional rubber mount. The proposed mount features the piezoelectric actuator which can be used to reduce the vibration at marine vessels or automotive vehicles. As a first step, a passive rubber mount is adopted and its dynamic characteristics are experimentally evaluated. Based on the geometry of the rubber mount, a rubber element for the active mount is manufactured and integrated with two piezostacks in series, in which the piezostack is operated as an inertial type of actuator. A conventional PID controller featured by the simple and easy implementation, is then designed to attenuate the non-resonant high frequency vibration transmitted from the base excitation. Finally, the control performances of a proposed active mount are evaluated in the wide frequency range and compared with those of the conventional rubber mount.

• Journal of IKEEE
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• v.24 no.2
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• pp.392-402
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• 2020

This paper proposes a solar tracking system without photo-sensors. The system can be classified into four modules: Solar Tracking, MPPT, ESS, and Real-Time Monitoring. Nine solar panels, as a basic unit, are adopted with grid structures of different heights to reduce wind influence and to enable solar tracking without photo-sensors. The low-cost MCU implements MPPT method which generates PWM switching signal for boost converter. The unit of ESS consists of three-series and four-parallel lithium-ion batteries in order to enable monitoring for abnormalities in temperature and electrical characteristics of battery. Four MCUs used in the system consists of two AVR Atmega128, and two Raspberry PI, and they exchanges operation informations. Experimental results of the proposed system show the solar tracking performance, the possibility of on-site and remote monitoring and the convenience of maintenance based on IoT technology.