• 전력전자학회논문지
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• 제9권5호
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• pp.405-412
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• 2004

본 논문에서는 1차 측이 20m이상의 긴 트랙케이블(Track Cable)로 2차 측은 큰 에어 갭(Air-gap)을 갖는 픽업코일(Pick-up Coil)로 구성되어 있는 비접촉 전원에 대해서 서술하였다. 이러한 비접촉 전원은 1차 측 누설 인덕턴스가 자화 인덕턴스보다 크기 때문에 커플링이 좋지 않아 1차 측의 에너지를 2차 측으로 효율적으로 전달 할 수 없다. 이와 같은 문제점을 개선하기 위하여 본 논문에서는 직렬공진 컨버터, 병렬공진 컨버터 그리고 직ㆍ병렬공진 컨버터(SPRC)의 주 회로를 해석하였고, 각 회로에 대한 전압이득 특성을 비교 검토하였다. 그리고 10kW 직ㆍ병렬공진 컨버터(SPRC)에 대한 실험결과를 서술했다.

• 융합신호처리학회논문지
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• 제10권4호
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• pp.225-232
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• 2009

유비쿼터스 컴퓨팅을 위한 상황 인식 기술은 수집된 컨텍스트 정보를 효과적으로 구조화하여 표현하고, 이러한 컨텍스트 정보를 이용하여 사용자의 의도를 파악한 후, 서비스를 제공하는 기술 등의 연구가 필요하다. 본 논문에서는 상황 인식 컴퓨팅을 위한 프레임워크인 WS-CAM으로 명명된 웹 서비스에 기반한 상황 인식 미들웨어를 제안한다. WS-CAM은 온톨로지 기반의 컨텍스트 모델을 사용하여 다양한 종류의 컨텍스트 정보에 대한 충분한 표현력과 추론 기능을 제공하고, 미들웨어로부터 응용 서비스로의 컨텍스트 정보 전달에 있어서 웹 서비스를 적용하여 미들웨어 독립적인 응용 개발을 이룰 수 있는 구조로 설계한다. 또한, WS-CAM의 유용성을 검증하기 위하여 유비쿼터스 컴퓨팅 환경에 기반을 둔 강의 서비스 시나리오를 기술하고, 웹 서비스 기반의 장점을 보이기 위하여 미들웨어 독립적인 시스템 확장의 예를 보인다. 강의 서비스에 적용한 WS-CAM은 도메인 환경 내의 컨텍스트 정보를 OWL 기반 온톨로지 모델로 효과적으로 표현하였고, 사용자 정의 규칙에 의하여 고수준의 컨텍스트 정보로 추론됨을 확인하였다. 또한, 웹 서비스에 의해 제공되는 다양한 웹 메서드를 통하여 컨텍스트 정보가 응용 서비스에 미들웨어 독립적으로 전달됨을 확인할 수 있었다.

• 한국전기전자재료학회논문지
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• 제26권3호
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• pp.204-208
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• 2013

In this study, $KNbO_3$-substituted (Li,Na,K)(Nb,Sb,Ta)$O_3$ ceramics were investigated to develop Pb-free composition ceramics for multilayer actuator and energy harvester applications. The X-ray diffraction analysis indicated that all samples were pure perovskite phase and no secondary phase was found. A tetragonality as a function of $KNbO_3$ substitution showed the maximum value at 1.5 mol% $KNbO_3$ and then decreased. The SEM image analysis showed the maximum grain size of $3.14{\mu}m$ at 1.5mol% $KNbO_3$. In the composition ceramics with 1.5 mol% $KNbO_3$ sintered at $1,100^{\circ}C$, excellent properties of density= 4.75 $g/cm^3$, electromechanical coupling factor ($k_p$)= 0.50 and piezoelectric constant($d_{33}$)= 290 pC/N were obtained, respectively, suitable for piezoelectric actuator and energy harvester applications.

• Nuclear Engineering and Technology
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• 제45권3호
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• pp.401-414
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• 2013

HTR50S is a small modular reactor system based on HTGR. It is designed for a triad of applications to be implemented in successive stages. In the first stage, a base plant for heat and power is constructed of the fuel proven in JAEA's $950^{\circ}C$, 30MWt test reactor HTTR and a conventional steam turbine to minimize development risk. While the outlet temperature is lowered to $750^{\circ}C$ for the steam turbine, thermal power is raised to 50MWt by enabling 40% greater power density in 20% taller core than the HTTR. However the fuel temperature limit and reactor pressure vessel diameter are kept. In second stage, a new fuel that is currently under development at JAEA will allow the core outlet temperature to be raised to $900^{\circ}C$ for the purpose of demonstrating more efficient gas turbine power generation and high temperature heat supply. The third stage adds a demonstration of nuclear-heated hydrogen production by a thermochemical process. A licensing approach to coupling high temperature industrial process to nuclear reactor will be developed. The low initial risk and the high longer-term potential for performance expansion attract development of the HTR50S as a multipurpose industrial or distributed energy source.

• 한국측량학회지
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• 제20권3호
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• pp.273-282
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• 2002

GIS는 다양한 영역에서 유용한 도구로서 자리잡고 있으나, 한편으로는, 복잡한 문제를 해결하기 위해서는 GIS가 수학, 공학적인 모델링툴과 결합되는 것이 필요하다는 견해와 연구결과가 등장하고 있다. LP(Linear Programming)는 주어진 자원을 최적으로 배분하는 문제에 사용되는 수학적인 기법이다. LP는 공간적인 표현을 포함하지 않기때문에 GIS의 기능들과 결합될 때 그 유용성이 높아질 수 있다. 그러나 전통적인 LP는 명료하게 조건이 주어질 경우에만 적합한 방법이므로, 토지이용계획과 같이 결정요소가 명확한 값으로 주어질 수 없는 경우에는 현실적으로 적용하기 어려워진다. 이 연구에서는, 이와 같이 불명료한(fuzzy) 상황을 다루기 위해 Fuzzy logic을 사용한 fuzzy-LP를 개발하고, 이를 GIS와 통합하는 방법론을 제시한다. 통합시스템에서 GIS는 Fuzzy-LP과정으로 데이터를 공급하거나 Fuzzy-LP의 결과값을 표현하는데 이용된다. 이 시스템을 토지이용배분문제에 적용하는 경우를 예시하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 추계학술대회 논문집 Vol.17
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• pp.167-170
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• 2004

The stochiometric mix of evaporating materials for the $CuGaT_2$ single crystal thin films was prepared from horizontal furnance. Using extrapolation method of X-ray diffraction patterns for the $CuGaTe_2$ polycrystal, it was found tetragonal structure whose lattice constant $a_0$ and $c_0$ were 6.025 ${\AA}$ and 11.931 ${\AA}$, respectively. To obtain the single crystal thin films, $CuGaTe_2$ mixed crystal was deposited on throughly etched semi-insulator GaAs(100) substrate by the Hot Wall Epitaxy (HWE) system. The source and substrate temperature were $670^{\circ}C$ and $410^{\circ}C$ respectively, and the thickness of the single crystal thin films is $2.1{\mu}m$. The crystalline structure of single crystal thin films was investigated by the photoluminescence and double crystal X-ray diffraction (DCXD). From the photocurrent spectrum by illumination of perpendicular light on the c - axis of the $CuGaTe_2$ single crystal thin film, we have found that the values of spin orbit coupling ${\Delta}s.o$ and the crystal field splitting ${\Delta}cr$ were $0.079\underline{1}eV$ and $0.246\underline{3}eV$ at 10 K, respectively. From the PL spectra at 10K, the peaks corresponding to free bound excitons and D-A pair and a broad emission band due to SA is identified. The binding energy of the free excitons are determined to be $0.047\underline{0}eV$ and the dissipation energy of the donor-bound exciton and acceptor-bound exciton to be $0.049\underline{0}eV$, $0.055\underline{8}eV$, respectively.

• 한국지리정보학회지
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• 제12권4호
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• pp.59-73
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• 2009

본 연구에서는 국내 산사태 발생이력 자료을 기반으로 GIS 기법을 적용하여 산사태 위험도 분석을 수행하였다. 이를 위해 한국도로공사에서 조사한 3년 동안의 총 596개 산사태 발생이력 자료와 산사태 발생요인 정보(기상정보, 지형정보, 토질정보)를 기초로 산사태 발생과 발생요인 간의 통계적 분석을 수행하여 상관관계를 산출하였다. 그 후 산출된 상관관계 토대로 총 6개의 래스터 래이어에 대한 가중치 및 위험도 인덱스를 도출하고, 최종적으로는 가중치를 적용한 래스터 계산기법을 통해 산사태 위험지도를 작성하였다. 본 연구의 적용 결과 산사태 위험도 산출을 위해 GIS 기법을 적용할 경우, 산사태 위험지도 작성을 위한 다양한 발생요인의 통합과 분석을 보다 손쉽고, 효율적으로 수행할 수 있을 것으로 판단되었다.

• Bulletin of the Korean Chemical Society
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• 제16권12호
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• pp.1193-1203
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• 1995

In this work, we focused on the setup of the tools for the analysis of the final rotational state distribution of photofragments in vibrational predissociations of triatomic van der Waals molecules A-B2. We found that reflection principle used for the direct photodissociation processes can also be applied to find out the final rotational state distributions for indirect photodissociation processes. The quantity which represents the strength of rovibrational coupling between the quasi-bound state and the final state is reflected into the mirror of the classical angular momentum function, instead of the initial state before light absorption used in the reflection principle of direct processes. The sign change in the first derivative of the interaction potential with respect to the bond distance of B2 is found to be the source of the binodal structures in the final rotational distributions of photofragments in the model system studied in this work. In MQDT analysis, short range eigenchannel basis functions were found to be localized in angle, in the previous work [Lee, C.W. Bull. Korean Chem. Soc. 1995, 16, 957.] and may be called angle functions. Angle functions enjoy simple geometrical structures which have simple functional relations with the final state distributions of photofragments. Two processes take place along the angle functions which resemble the quasi-bound state and dominate over other processes. Two such angle functions are found to be not only localized angularly but also localized either one of ends of B2 in motions along the bond of B2. These dominating photodissociation processes, however, cancel each other. This cancellation causes photodissociation to depend sensitively on the interaction potential at other angles than the dominant one. Part of potential surface where much larger torque exists can now play an important role in photodissociation. MQDT also enables us to see which processes play important roles after cancellation. This is done by examining the amounts of time delayed by asymptotic eigenchannels.

• Bulletin of the Korean Chemical Society
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• 제12권6호
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• pp.606-612
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• 1991

We have carried out an extended Huckel calculation to rationalize the role of $CuO_3$ chains and the size effect of the charged model clusters for the following charged model culsters : ${{Cu_6}{O_{21}}^{28-},\;{{Cu_6}{O_{22}}^{30-}\;,{{Cu_9}{O_{30}}^{39-}\;,{{Cu_9}{O_{32}}^{43-}\;,{{Cu_{12}{O_{38}}^{48-}\;,{{Cu_{15}{O_{50}}^{65-}\;,{{Cu_{18}{O_{54}}^{66-}\;,{{Cu_{18}{O_{55}}^{68-}\;,{{Cu_{24}{O_{70}}^{84-}\;and\;{{Cu_{27}{O_{78}}^{93-}$ for high-$T_c$ superconductor $YBa_2Cu_3O_7$: ${{Cu_6}{O_{18}}^{22-}\;,{{Cu_9}{O_{26}}^{31-}}\;,{{Cu_{12}{O_{32}}^{36-}\;,{{Cu_{15}{O_{42}}^{49-}\;,{{Cu_{18}{O_{46}}^{50-}\;,{{Cu_{24}{O_{60}}^{64-}\;and\;{{Cu_{27}{O_{66}}^{69-}$ for insulator $YBa_2Cu_3O_6$. The results show that the electronic structures and properties of the charged model clusters relating to high-$T_c$ superconductor are very sensitive to the size change of the clusters with various environmental effects, wherease those of the charged model clusters for insulator $YBa_2Cu_3O_6$ are monotonous to the size change. The $CuO_3$ chains along the b-direction may yield cooperative electronic coupling with the $CuO_2$ layers in determining both conducting and superconducting properties of $YBa_2Cu_3O_{7-x}$ system.

• Bulletin of the Korean Chemical Society
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• 제19권6호
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• pp.654-660
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• 1998

$[Fe^{II}Fe^{III}BPLMP(OAc)_2](BPh_4)_2$ (1), a new model for the reduced form of the purple acid phosphatases, has been synthesized by using a dinucleating ligand, 2,6-bis[((2-pyridylmethyl)(6-methyl-2-pyridylmethyl)amino) methyl]-4-methylphenol (HBPLMP). Complex I has been characterized by X-ray diffraction method as having (μ-phenoxo)bis(acetato)diiron core. Complex 1 was crystallized in the monoclinic space group C2/c with the following cell parameters: a=41.620(6) Å, b=14.020(3) Å, c=27.007(4) Å, β=90.60(2)°, and Z=8. The iron centers in the complex 1 are ordered as indicated by the difference in the Fe-O bond lengths which match well with typical $Fe^{III}-O\; and\; Fe^{II}-O$ bond lengths. Complex 1 has been studied by electronic spectral, NMR, EPR, SQUID, and electochemical methods. Complex 1 exhibits strong bands at 592 nm, 1380 nm in $CH_3CN$ (ε = 1.0 × 103 , 3.0 × 102). These are assigned to $phenolate-to-Fe^{III}$ and intervalence charge-transfer transitions, respectively. Its NMR spectrum exhibits sharp isotropically shifted resonances, which number half of those expected for a valence-trapped species, indicating that electron transfer between $Fe^{II}\;and\;Fe^{III}$ centers is faster than NMR time scale. This complex undergoes quasireversible one-electron redox processes. The $Fe^{III}_2/Fe^{II}Fe^{III}\;and\;Fe^{II}Fe^{III}/Fe^{II}_2$ redox couples are at 0.655 and -0.085 V vs SCE, respectively. It has $K_{comp}=3.3{\times}10^{12}$ representing that BPLMP/bis(acetate) ligand combination stabilizes a mixed-valence $Fe^{II}Fe^{III}$ complex in the air. Complex 1 exhibits a broad EPR signal centered near g=1.55 which is a characteristic feature of the antiferromagnetically coupled high-spin $Fe^{II}Fe^{III}$ system $(S_{total}=1/2)$. This is consistent with the magnetic susceptibility study showing the weak antiferromagnetic coupling $(J= - 4.6\;cm^{-1},\; H= - 2JS_1{\cdot}S2)$ between $Fe^{II}\; and \;Fe^{III}$center.