• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 1997년도 춘계학술대회 학술발표 논문집
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• pp.77-80
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• 1997

In this paper, we propose a new fitnesness function of GA for slowly time-varying plant. Previous Takgi-Sugeno model based controller is used as basic control scheme and Controller parameters are tuned by GA with the proposed fitness function includes the information of model parameter variation and has better performance robustness than the previous ones. We illustrate the effectiveness of the proposed fitness function by simple simulation example.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2006년도 하계종합학술대회
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• pp.575-576
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• 2006

It was analyzed qualitatively the light extraction in GaN-on-sapphire LEDs based on a simple model. The light extraction efficiency in the LEDs is simulated numerically by using ray tracing method. In the present study, the extraction efficiency was simulated on three different types of LEDs, which a have a different pattered sapphire substrate. And, the role of the patterned sapphire substrate are analyzed and discussed. Based on the analysis, the improvements of extraction efficiency in the LED structures were discussed and these analyses are helpful in the design of high brightness GaN LEDs.

• 산업공학
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• 제20권4호
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• pp.504-514
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• 2007

The multicast routing problem lies in the composition of a multicast routing tree including a source node and multiple destinations. There is a trade-off relationship between cost and delay, and the multicast routing problem of optimizing these two conditions at the same time is a difficult problem to solve and it belongs to a multi-objective optimization problem (MOOP). A multi-objective genetic algorithm (MOGA) is efficient to solve MOOP. A micro-genetic algorithm(${\mu}GA$) is a genetic algorithm with a very small population and a reinitialization process, and it is faster than a simple genetic algorithm (SGA). We propose a multi-objective micro-genetic algorithm (MO${\mu}GA$) that combines a MOGA and a ${\mu}GA$ to find optimal solutions (Pareto optimal solutions) of multicast routing problems. Computational results of a MO${\mu}GA$ show fast convergence and give better solutions for the same amount of computation than a MOGA.

• 제어로봇시스템학회논문지
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• 제9권8호
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• pp.623-631
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• 2003

We have fabricated the two-dimensional inverted pendulum system and designed its controller. The two-dimensional inverted pendulum system, which is composed of X-Y table, is actuated through timing belt by each of two geared DC motors. And the control goal is that the rod is always kept to a vertical position to any distrubance and is quickly moved to the desired position. Because this system has generally nonlinear dynamic characteristics and X-axis and Y-axis move together, it is very difficult to find its exact mathematical model and to design its controller. Therefore, we have designed the PID controller with simple structure and excellent performance. Genetic algorithm(GA), which is blown as one of probabilistic searching methods, and human's heuristic control strategy are introduced to design an optimal PID controller. The usefulness of the proposed GA based PID coefficient searching technique is verified through the experiments and computer simulations.

• 전자공학회논문지A
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• 제31A권8호
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• pp.62-71
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• 1994

A novel semiconductor device is proposed to be used as a processing element for the implementation of pulse-mode neural networks which consists of alternating n' GaAs quantum wells and undoped AlGaAs barriers sandwitched between n' GaAs cathode and P' GaAs anode and in simple circuit in conjunction with a parallel capacitive and resistive load the trigger circuit generates neuron-like pulse train output mimicking the function of axon hillock of biological neuron. It showed the sigmoidal relationship between the frequency of the pulse-train and the applied input DC voltage. In conjunction with MQWIMD the various neural circuits are proposed especially a neural chip monolithically integrated with photodetectors in order to perfrom the pattern recognition.

• 전기학회논문지
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• 제61권11호
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• pp.1646-1649
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• 2012

The $O_2$ annealing technique has considerably suppressed the leakage current of GaN power devices, but this forms NiO at Ni-based Schottky contact with increasing on-resistance. The purpose of the present study was to fabricate 1.5 kV GaN Schottky barrier diodes by improving $O_2$-annealing process and GaN buffer. The proposed $O_2$ annealing performed after alloying ohmic contacts in order to avoid NiO construction. The ohmic contact resistance ($R_C$) was degraded from 0.43 to $3.42{\Omega}-mm$ after $O_2$ annealing at $800^{\circ}C$. We can decrease RC by lowering temperature of $O_2$ annealing. The isolation resistance of test structure which indicated the surface and buffer leakage current was significantly increased from $2.43{\times}10^7$ to $1.32{\times}10^{13}{\Omega}$ due to $O_2$ annealing. The improvement of isolation resistance can be caused by formation of group-III oxides on the surface. The leakage current of GaN Schottky barrier diode was also suppressed from $2.38{\times}10^{-5}$ to $1.68{\times}10^{-7}$ A/mm at -100 V by $O_2$ annealing. The GaN Schottky barrier diodes achieved the high breakdown voltage of 700, 1400, and 1530 V at the anode-cathode distance of 5, 10, and $20{\mu}m$, respectively. The optimized $O_2$ annealing and $4{\mu}m$-thick C-doped GaN buffer obtained the high breakdown voltage at short drift length. The proposed $O_2$ annealing is suitable for next-generation GaN power switches due to the simple process and the low the leakage current.

• Archives of Pharmacal Research
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• 제23권5호
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• pp.525-530
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• 2000

mST3GaIV synthesizes ganglioside GM3, the precursor for simple and complex a- and b- series gangliosides, and the expression and regulation of mST3GaIV (CMP-NeuAc: lactosylceramide $\alpha$2,3-sialyltransferase) activity is central to the production of almost all gangliosides, a class of glycosphingolipids implicated in variety of cellular processes such as transmembrane signaling, synaptic transmission, specialized membrane domain formation and cell-cell interactions. To understand the developmental expression of mST3GaIV in mice, we investigated the spatial and temporal expression of mST3GaIV mRNA during the mouse embryogenesis [embryonic (E) days; 19, E11, E13, E15] by in situ hybridization with digoxigenin-labeled RNA probes. All tissues from 19 and E11 were positive for mST3GaIV mRNA. On E13, mST3GaIV mRNA was expressed in various neural and non-neural tissues. In contrast to these, on E15, the telencephalon and liver produced a strong expression of mST3GaIV which was a quite similar to that of E13. In this stage, mST3GaIV mRNA was also expressed in some non-neural tissues. These data indicate that mST3GaIV is differently expressed at developmental stages of embryo, and this may be importantly related with regulation of organogenesis in mice.

• 한국전기전자재료학회논문지
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• 제21권7호
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• pp.603-609
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• 2008

Photoluminescence (PL) of neutron-irradiated GaN films and nanowires is investigated in this study. The GaN films and nanowires were irradiated by neutron beams in air at room temperature, and the neutron-irradiated films and nanowires were annealed in an atmosphere of $NH_3$ at temperatures ranging from 500 to $1100^{\circ}C$. The line-shapes of the PL spectra taken from the neutron-irradiated GaN films and nanowires were changed differently with increasing annealing temperature. In this study, light-emitting centers created in the neutron-irradiated GaN films and nanowires are examined and their origins are discussed. In addition, it is suggested here that the neutron-transmutation-doping is a simple and useful means of homogeneous impurity doping into nanowires with control of the doping concentration.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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• pp.1096-1099
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• 2006

$II-III_2-(S,Se)_4$ structured of phosphor have been used at various field because those have high luminescent efficiency and broad emission band. Among these phosphors, europium doped $BaGa_2S_4$ was prepared by solid-state method and we try to look into an application possibility due to an emissive property of UV region. Also, general sulfide phosphors were synthesized by using injurious $H_2S\;CS_2$ gas. However, this study prepared $BaGa_2S_4:Eu^{2+}$ phosphor is addition to excess sulfur under 5% $H_2/95%\;N_2$ reduction atmosphere. So, this process could large scale synthesis because of non-harmfulness and simple process. The photo-luminescence efficiency of the prepared $BaGa_2S_4:Eu^{2+}$ phosphor increased 20% than commercial $SrGa_2S_4:Eu^{2+}$ phosphor. The prepared $BaGa_2S_4:Eu^{2+}$ could apply to green phosphor for white LED of three wavelengths.

• 대한화학회지
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• 제50권2호
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• pp.137-140
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• 2006

Eu2+를 활성제로 한(Sr,Ba)2Ga2SiO7 녹색 형광체를 일반적인 고상 반응으로 합성하였고, 그 합성된 형광체의 광발광 특성을 연구하였다. 형광체 제조 시, 마노유발에서 보다 효과적인 혼합을 위하여 아세톤을 사용하여 혼합하였다. 또한 25%H2/75%N2의 혼합기체를 이용한 환원조건에서 단순한 공정으로 형광체를 합성하였다. 이 형광체는 405 nm의 여기 파장하에서 효율적으로 발광되는 녹색 밴드(513 nm)를 갖고 있기 때문에 백색 LED(Light Emitting Diode)램프에 응용할 수 있다.