• Journal of Electrical Engineering and Technology
• /
• 제5권4호
• /
• pp.597-605
• /
• 2010

This paper presents a contribution to parameter identification of a non-linear system using a new strategy to improve the genetic algorithm (GA) method. Since cost function plays an important role in GA-based parameter identification, we propose to improve the simple version of GA, where weights of the cost function are not taken as constant values, but varying along the procedure of parameter identification. This modified version of GA is applied to the induction motor (IM) as an example of nonlinear system. The GA cost function is the weighted sum of stator current and rotor speed errors between the plant and the model of induction motor. Simulation results show that the identification method based on improved GA is feasible and gives high precision.

• Journal of Electrical Engineering and information Science
• /
• 제2권6호
• /
• pp.106-110
• /
• 1997

The binding energies of the ground state of both the heavy-hole and light-hole excitons in a GaAs(In\ulcornerGa\ulcornerAs) quantum well sandwiched between two semi-infinite Al\ulcornerGa\ulcornerAs(InP) layers are calculated as a function of well width in the presence of an arbitray magnetic field. A variational approach is followed using very simple trial wave function. The applied magnetic field is assumed to be parallel to the axis of growth and the binding energies are calculated for a finite value of the height of the potential barrier. The exciton binding energies for a given value of the magnetic field are found to be increased than their values in a zero magnetic field due to the compression of their wave functions within the well with the applied magnetic field.

• Korean Chemical Engineering Research
• /
• 제48권4호
• /
• pp.511-514
• /
• 2010

불소계 고분자 물질인 $Cytop^{TM}$ 박막을 간단하고 경제적인 스핀코팅 방법을 이용하여 반도체 표면에 선택적으로 형성시킨 후, AlGaN/GaN HEMT 소자의 반도체 보호막(passivation layer)으로써 활용가능성을 고찰하기 위하여 전기적 특성이 분석되었다. $Cytop^{TM}$ 보호막이 적용된 AlGaN/GaN HEMT 소자와 적용되지 않은 소자의 게이트 래그 특성이 비교되었다. 보호막이 적용된 소자는 dc 대비 65%의 향상된 펄스 드레인 전류를 보였다. HEMT 소자의 rf 특성이 측정되었으며, $Cytop^{TM}$ 박막이 적용된 소자는 PECVE $Si_3N_4$ 보호막이 적용된 소자와 유사한 소자 특성을 나타냈다. 이는 게이트와 드레인 사이에 존재하는 표면상태 트랩의 보호막에 의한 감소에 의한 것으로 판단된다.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
• /
• pp.385-386
• /
• 2008

In this paper, a simple dual band filter chip is designed with 0603 case size using IPD technology. The dual-band filter achieves high frequency band at 2.5 GHz and low frequency band at 1.8 GHz. The insertion losses in high frequency band and low frequency band are -0.195 dB and -0.146 dB, respectively. The return losses in these bands are -22.7 dB and -22.8 dB, respectively. The simple dual-band filter based on SI-GaAs substrate is designed within die size of about 1.3 $mm^2$.

• 한국지능시스템학회논문지
• /
• 제19권3호
• /
• pp.432-436
• /
• 2009

We have developed a new optimization algorithm termed simple bacteria cooperative optimization (sBCO) based on bacteria behavior patterns [1]. In [1], we have introduced the algorithm with basic operations and showed its feasibility with some function optimization problems. Since the sBCO was the first version with only basic operations, its performance was not so good. In this paper, we adopt a new operation, rank replacement, to the sBCO for improving its performance and compare its results to those of the simple genetic algorithm (sGA) which has been well known and widely used as an optimization algorithm. It was found from the experiments with four function optimization problems that the sBCO with rank replacement was superior to the sGA. This shows that our algorithm can be a good optimization algorithm.

• ETRI Journal
• /
• 제17권3호
• /
• pp.17-43
• /
• 1995

We present a comprehensive derivation of the transport of holes involving an interacting two-valence-band system in terms of a generalized relaxation time approach. We sole a pair of semiclassical Boltzmann equations in a general way first, and then employ the conventional relaxation time concept to simplify the results. For polar optical phonon scattering, we develop a simple method th compensate for the inherent deficiencies in the relaxation time concept and apply it to calculate effective relaxation times separately for each band. Also, formulas for scattering rates and momentum relaxation times for the two-band model are presented for all the major scattering mechanisms for p-type GaAs for simple, practical mobility calculations. Finally, in the newly proposed theoretical frame-work, first-principles calculations for the Hall mobility and Hall factor of p-type GaAs at room temperature are carried out with no adjustable parameters in order to obtain a direct comparison between the theory and recent available experimental results, which would stimulate further analysis toward better understanding of the complex transport properties of the valence band. The calculated Hall mobilities show a general agreement with our experimental data for carbon doped p-GaAs samples in a range of degenerate hole densities. The calculated Hall factors show $r_H$=1.25~1.75 over all hole densities($2{\times}10^{17}{\sim}1{\times}10^{20}cm^{-3}$ considered in the calculations.

• 한국재료학회지
• /
• 제16권8호
• /
• pp.479-484
• /
• 2006

Highly c-axis oriented poly-crystalline GaN with a dimension of $1{\sim}3\;{\mu}m$ was deposited on $c-Al_2O_3$ substrate by vapor transport epitaxy (VTE) method at the temperature range of $900{\sim}1150^{\circ}C$. XRD intensities from (00'2) plane of grown GaNs were increased with reaction conditions which indicate the improvement of the crystal quality. In the PL spectra measured at 10 K, the spectrum composed with the neutral-donor bound exciton-related emission at 3.47 eV, crystal defect-related emission band at 3.42 eV and with its phonon replicas. The fact that intensity of $I_2$ were increased and FWHM were decreased with growth conditions means that the quality of GaN crystals were improved. With this simple VTE technology, we confirm that the GaNs were simply deposited on sapphire substrate and crystal quality related to optical properties of GaN grown by VTE were relatively good. PL emission without deep level emission in spite of polycrystalline structure can be applicable to the fabrication of large area and low cost optical devices using poly-GaN grown by VTE.

• 한국버섯학회지
• /
• 제13권3호
• /
• pp.175-180
• /
• 2015

본 연구에서는 국내외에서 수집한 A. bisporus 45계통과 19 Agaricus spp.를 포함한 64 Agaricus 계통으로부터 genomic DNA를 추출하고 7 종류의 ISSR primer를 사용하여 PCR 다형성 분석을 실시 한 바 (GA)T, (AG)YC, (GA)C and (CTC)의 ISSR primer에서 양송이 계통간 PCR다형성이 관찰 되었다. ISSR-PCR다형성 밴드가 유전적 유사도 산출에 이용되어 UPGMA cluster분석을 적용 dendrogram을 작성 한 결과 A. bisporus의 계통은 7 group으로 분류 되었으며 유사성 함수가 group 간에는 유사성 함수가 0.78에서 0.89의 유연관계를 보였다. 국내에서 최근에 개발된 새정, 새아, 새도, 새연과 교배모본인 ASI1346이 같은 그룹내에서 0.90이상의 유사성함수로 근연관계를 나타내었다. ISSR-PCR다형성 검출 결과 ASI 1038와 유래 단핵균주 S1038297와 ASI 1346S유래 S 737-110는 PCR다형성 밴드가 현저히 적게 증폭 된 것을 확인 할 수 있었다.

• 한국지능정보시스템학회:학술대회논문집
• /
• 한국지능정보시스템학회 1999년도 추계학술대회-지능형 정보기술과 미래조직 Information Technology and Future Organization
• /
• pp.323-335
• /
• 1999

In this paper, we propose a new hybrid model of artificial neural networks(ANNs) and genetic algorithm (GA) to optimal feature transformation and feature weighting. Previous research proposed several variants of hybrid ANNs and GA models including feature weighting, feature subset selection and network structure optimization. Among the vast majority of these studies, however, ANNs did not learn the patterns of data well, because they employed GA for simple use. In this study, we incorporate GA in a simultaneous manner to improve the learning and generalization ability of ANNs. In this study, GA plays role to optimize feature weighting and feature transformation simultaneously. Globally optimized feature weighting overcome the well-known limitations of gradient descent algorithm and globally optimized feature transformation also reduce the dimensionality of the feature space and eliminate irrelevant factors in modeling ANNs. By this procedure, we can improve the performance and enhance the generalisability of ANNs.

• Bulletin of the Korean Chemical Society
• /
• 제34권6호
• /
• pp.1741-1744
• /
• 2013

A new polymeric catalyst was prepared by supporting $GaCl_3$ on cross-linked polyvinylpyrrolidone ($GaCl_3$/PVP). This catalyst was employed for efficient and regioselective ring-opening reaction of epoxides by various alcohols under solvent-free conditions at room temperature. In our procedure, this heterogeneous catalyst was used at neutral and mild reaction conditions to afford high yields of ${\beta}$-alkoxy alcohols. Also, regioselective conversion of epoxides to ${\beta}$-azidohydrines was accomplished by sodium azide in MeOH in the presence of $GaCl_3$/PVP at room temperature. $GaCl_3$/PVP is a non-hygroscopic and recoverable catalyst and is easily separated from reaction mixture by a simple filtration and re-used repeatedly. Also, this catalyst has good handling and can be stored for long time without any reducing of its reactivity.