• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.5
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• pp.173-179
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• 2017

Advanced countries, animal wastes are produced using bioenergy and methane gas technology. In Korea, many researches are being actively carried out to develop livestock manure as a resource technology rather than a animal waste. However, the production of bio-gas using livestock manure is still in the process of development of functional livestock and compost because of low economic efficiency with livestock manure recycling technology. In this paper, in order to accurately estimate the manure output, It will calculate the manure excretion if you have finished input the number of pigs. In addition, we simulated the fertilization rate of three elements of NPK fertilizer per 100 square meters automatically.

• 전자공학회논문지 IE
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• v.43 no.3
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• pp.22-27
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• 2006

This paper presents the control system of high-efficiency automotive 35W metal-halide lamp ballast using the new control method and planar transformer. In this paper, the electronic ballast is designed so that digital control method by microcontroller can be applied to the electronic ballast for the lamp requirement and peripheral environment in order that metal-halide lamp, which has the complicated transient features, is to be applied to the automobile even if it has superior features in brightness, color rendering, light efficiency, and lifespan compared to the conventional halogen lamp. Also, the efficiency increase of the ballast is devised by being varied the switching frequency of Flyback Converter following the battery input voltage of the automobile. Being designed for high-frequency switching transformer of converter in planar form, reduction of loss, weight, overall size are realized and efficient power control in the automobile that had the limited energy and the limited space of battery is devised. The results of the proposed system is verified through various experiment results.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.2
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• pp.327-340
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• 2015

General Circulation Models (GCMs) are the basic tool used for modelling climate. However, the spatio-temporal discrepancy between GCM and observed value, therefore, the models deliver output that are generally required calibration for applied studies. Which is generally done by Multi-Model Ensemble (MME) approach. Stochastic downscaling methods have been used extensively to generate long-term weather sequences from finite observed records. A primary objective of this study is to develop a forecasting scheme which is able to make use of a MME of different GCMs. This study employed a Nonstationary Hidden Markov Chain Model (NHMM) as a main tool for downscaling seasonal ensemble forecasts over 3 month period, providing daily forecasts. Our results showed that the proposed downscaling scheme can provide the skillful forecasts as inputs for hydrologic modeling, which in turn may improve water resources management. An application to the Nakdong watershed in South Korea illustrates how the proposed approach can lead to potentially reliable information for water resources management.

• Journal of Broadcast Engineering
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• v.18 no.2
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• pp.185-195
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• 2013

In this paper, we propose a video summarization technique on a smartphone, based on spatiotemporal saliency. The proposed technique detects scene changes by computing the difference of the color histogram, which is robust to camera and object motion. Then the similarity between adjacent frames, face region, and frame saliency are computed to analyze the spatiotemporal saliency in a video clip. Over-segmented hierarchical tree is created using scene changes and is updated iteratively using mergence and maintenance energies computed during the analysis procedure. In the updated hierarchical tree, segmented frames are extracted by applying a greedy algorithm on the node with high saliency when it satisfies the reduction ratio and the minimum interval requested by the user. Experimental result shows that the proposed method summaries a 2 minute-length video in about 10 seconds on a commercial smartphone. The summarization quality is superior to the commercial video editing software, Muvee.

• The Transactions of the Korean Institute of Power Electronics
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• v.3 no.4
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• pp.315-322
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• 1998

Power conversion system must increase switching frequency in order to achieve small size, light weight and low noise. However, the switches of converter are subject to high switching power losses and switching stresses. As a result, the power system has a lower efficiency. In this paper, the authors propose an AC-DC boost converter of high efficiency by partial resonant switching mode. The switching devices in the proposed circuit are operated with soft switching and the control technique of those is simplified for switch to drive in constant duty cycle. The partial resonant circuit makes use of a inductor using step up and a condenser of loss-less snubber. Besides, by regenerating energy, that is charged in a loss less snubber condenser of a snubber adopted to a common circuit, toward an input source part, this circuit can get increased efficiency. as merit. The result is that the switching loss is very low, the efficiency and power factor of system is high. The proposed converter is deemed the most suitable for high power applications where the power switching devices are used.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.1C
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• pp.64-71
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• 2003

In this paper, we proposed an algorithm that shorten coding time maintaining image quality in JPEG2000, which is the standard, of still image compression. This method encodes only the bit plane selected as appropriate truncation point for output bitstream, obtained from estimation of frequency distribution for whole image. Wavelet characterized by multi-resolution has vertical, horizontal, and diagonal frequency components for each resolution. The frequency interrelation addressed above is maintained thorough whole level of resolution and represents the unique frequency characteristics for input image. Thus, using the frequency relation at highest level, we can pick the truncation point for the compression time decrease by estimating code bits at encoding each code block. Also, we reduced the encoding time using simply down sampling instead of low-pass filtering at low-levels which are not encoded in color component of lower energy than luminance component. From the proposed algorithm, we can reduce about 15~36% of encoding time maintaining PSNR 30$\pm$0.5㏈.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.140-140
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• 2017

4륜 장착 자동차의 토크 전달은 2륜 구동, 4륜 구동 모드를 간단히 전환하는 방식(part time 4WD)과 항시 사륜 구동 모드에서 전후륜의 토크 전달비를 제어하는 방식(AWD, all wheel drive)이 있다. 경제의 발달에 따라서 취미 인구의 확대로 국내에만 180만 명의 R/C car 사용자가 있다. 이 중 2WD-4WD의 전환을 differential lock mechanism으로 구현한 수입산 모델의 가격이 1,000,000원을 호가하지만 가변 제어 방식이 아닌, 정차 후 2-4륜 구동 전환 방식을 적용하고 있으며 상대적으로 내구성이 떨어진다. DC motor의 출력이 늘어나고 배터리의 성능이 좋아진 현재 소형 RC car의 최고 속도는 80 km/h 정도로 빨라졌다. 그러나 마찰 계수가 낮은 노면(실내의 대부분 평활 처리된 복도)에서는 2륜 구동 모드의 활용도가 매우 낮다. 미끄러운 노면에서 후륜 구동 모드로는 oversteer가 발생하여 차량이 스핀하기 쉽고 전륜 구동 모드로는 understeer가 발생하여 제대로 된 코너링이 어렵다. 상시 4륜 구동 모드는 에너지 소모가 크고 전후륜이 tight coupling되어 있는 문제 때문에 일반적인 노면에서 부드러운 코너링이 잘 이루어지지 않는 문제가 있다. 본 연구에서 제안하는 방식은 그림 1와 같이 center shaft의 중간에 영구 자석으로 만들어진 토크 전달용 판이 있고 그 사이에 자계를 차폐할 수 있는 강자성체 셔터를 서보 기구에 연결하여 서보 회전각에 따라서 구동 쪽의 토크가 피구동축으로 전달되는 양을 연속 가변제어할 수 있다. 토크 전달용 판의 차폐 면적에 따른 토크 전달양을 전/후륜 바퀴의 Static torque를 통해 측정하였으며(그림 2), 공중 상태에서 즉 공기저항만을 고려한 상태에서의 RPM 회전수 차이 측정(그림3)을 통해 구동 쪽의 회전수가 피구동축으로 전달되는 양을 측정하여 연속가변 토크 제어 전달 기구의 성능을 확인하였다. 이 기구는 현재 1차적으로는 remote controller의 ch 3(ON/OFF제어 방식)에 연결하여 특정한 양의 토크를 전륜 쪽으로 보낼 수 있도록 구현이 가능하며, ch 2(PID제어 방식)에 연결하여 연속 가변 조절이 가능하도록 구현이 가능하다. 부가적으로 Arduino board를 내장하여 전후륜의 휠센서에서 입력되는 신호를 감지하여 자동적으로 전후륜에 배분되는 토크를 제어할 수 있도록 설계 중에 있다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.3 no.1
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• pp.13-24
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• 1983

A mathematical model for the two-dimensional unsteady flow was developed by introducing Abbott's implicit finite difference operator and double sweep algorithm, which could be applied to simulate the respose of a harbor against the intrusion of long waves through the entrance connected to open sea. In order to improve its accuracy corresponding to the field phenomena, bottom resistance, Coriolis force, wind effect terms were included and wave direction and radiating effect was considered. The result of seiche test was always stable and the amplitude was accurate. Some phase shift was occured, but it could be reduced by using small values of Courant number and many points per a wave length as well. A comparision with the Ippen and Goda's theoritical and hydraulic experimental works was fulfilled.

• Journal of the Korean Vacuum Society
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• v.6 no.1
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• pp.85-90
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• 1997

A new ionized sputtering process was developed to fill small trench or via using additional ionizing mechanism of sputtered particles from 32cm $AlCu_x$(x=0.5%) cathode target with rotating magnet, then drawn toward substrate by small negative DC potential. The radial uniformity in RFI magnetron sputtering was studied by plasma diagnosis and appropriate RFI coil design to improve it. Optical emission intensities of excited species. $Ar^{\circ}, \;Ar^+;Al^+, \;Al^{\circ}$ are measured across the radial direction and showed close correlation with deposit's bottom to top thickness ratios in trenches and vias of submicron opening and 1.5 aspect ratio. After increase of the diameter of RF coil from 29 cm to 32 cm and improved the power leading feedthrough symmetry by removal of asymmetric single turn region, there was an increase of uniformity from 7.5% to 1.5% in bottom to top thickness ratio in 0.6 $\mu\textrm{m}$ vias.

• Journal of the Korean Vacuum Society
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• v.8 no.1
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• pp.75-82
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• 1999

Ion energy is one of the crucial property in thin film deposition by internal ICP assisted I-PVD. As ion energy is determined by the difference between the plasma potential and the substrate bias potential, ICP excitation frequency was tested with medium frequency of 4 MHz and two types of tuning circuits, alternate and floating LC network with a biasing resistor, were tested. The results showed that plasma potential was less than 5 V in a range of Ar pressures, 5mTorr to 30 mTorr, at 4 MHz RF 600 W and 60 V of maximum RF antenna voltage was maintained either at RF input or output terminal. By proper control of RLC circuit installed after after RF antenna, 50V of RF induced voltage on RF antenna was obtained at 500W input power. The total impedance of RF antenna and plasma was around 10$\Omega$, and minimum RF voltage was obtained with a condition of lowest reactance at most 0.05$\Omega$.