• 한국재료학회:학술대회논문집
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• 한국재료학회 2007년도 추계학술발표대회 및
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• pp.153.2-153.2
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• 2007

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집
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• pp.371-374
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• 2002

Bismuth lanthanum titanate thin films with excess Bi contents were prepared onto Pt/Ti/$SiO_2$/Si substrate by metalorganic decomposition (MOD) technique. The structure and morphology of the films were analyzed using X-ray diffraction (XRD) and atomic force microscopy (AFM), respectively. From the XRD analysis, BLT thin films show polycrystalline structure and the layered-perovskite phase was obtained over 10% excess of Bi contents. As a result of ferroelectric characteristics related to the Bi content of the BLT thin film, the remanent polarization and dielectric constant decreased with increasing over Bi content of 10 % excess. The BLT film with Bi content of 10% excess was measured to have a dielectric constant of n9 and dielectric loss of 1.85[%]. The BLT thin films showed little polarization fatigue test up to 3.5 x $10^{9}$ bipolar switching cycling.

• 한국전자파학회논문지
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• 제22권9호
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• pp.881-887
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• 2011

본 논문에서는 안테나의 인접하는 방사체 부분 사이의 신호 간섭에 따른 커플링 현상을 이용하여 대역 특성에 대응되는 수직 방사체를 가진 안테나를 제안하였다. 전류 상쇄를 최소화시키기 위해 수직형 도전성 방사체를 이용하였고, 기존 메탈 프레스 내장형 안테나에 대비하여 방사 효율을 높이고, 큰 대역폭을 갖는 안테나를 설계하였다. 제안한 안테나는 GSM850/900, DCS1800, PCS1900 대역을 만족하였으며, 측정된 반사 손실에 의한 대역폭은 기존 메탈 프레스 내장형 안테나에 비해 저주파수 대역에서는 28 % 주파수 대역폭이 향상된 91 MHz, 고주파수 대역에서는 14 % 향상된 222 MHz의 대역폭을 가지는 것을 확인하였다. 또한, 제안한 안테나의 측정된 방사 이득과 효율은 전 대역에서 -4.956~-0.617 dBi, 31.80~86.36 %로 소형 안테나임에도 불구하고 매우 양호한 특성을 보였다. 이를 통해 수직 방사체로 구현함으로써 대역폭의 개선과 함께 방사 이득 향상에도 도움이 되는 것을 확인하였다.

• Journal of Magnetics
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• 제12권3호
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• pp.93-96
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• 2007

We investigated the electronic structure and magnetic properties of zinc-blende CrP/SrBi interface by using the all-electron full-potential linearized augmented plane wave method within the generalized gradient approximation. It is found that the half-metallicity is destroyed when the two half-metals are in contact. Magnetic moments of the atoms forming the supercell differ considerably from the respective values obtained for the bulk structures of the two materials. Cr atoms being and not being in contact with Bi atoms have magnetic moment 3.43 and $2.69{\mu}_B$, respectively. Bi atoms lose their majority electrons which results in their negative polarization. Alkaline Sr atoms are very weakly negatively polarized. The spin distribution within the supercell is such that well separated regions of positive and negative polarization are seen, especially around the layer of P atoms being in contact with the layer of Sr atoms.

• 한국정보시스템학회지:정보시스템연구
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• 제16권4호
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• pp.269-286
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• 2007

Business Incubators(BI) guide starting-up firms through their growth process and as such constitute a strong instrument to promote innovation and entrepreneurship. This study classified the incubating services into communication, physical facilities, human resources, marketing, financial, legal, technology, and networking services. The research problem was tested with data from 103 BI centers and 561 starting-up firms in BI. The results from the survey are as follows: First, incubating services to important for the BI's performance are networking, communication, human resources, physical facilities, and marketing services. Second, the incubating services to satisfy on the firms in the BI are financial, human resources, marketing, communication, networking, and physical facilities services. Third, there are the differences between BI center and the firms in the BI by each incubating service except communication service. Finally, the results of MSEM(Multi-group Structured Equation Modeling) indicate the communication and networking services are more strongly affected to the performance at the BI centers. Vice versa, the marketing and financial services are more strongly affected to the satisfaction at the firms in the BI centers. Starting-up firms in business incubators showed strong desire to receive better support in such fields as marketing and financial services. BI needs to recognize such demand and provide improved services in such areas. Starting-up firms did not recognize the utility and importance of services in networking with other firms and supporting human resources. BI needs to promote services in such areas. Concerning communication services and physical facility support service, both BI and starting-up firms showed satisfactory levels of services.

• Bulletin of the Korean Chemical Society
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• 제33권7호
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• pp.2305-2308
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• 2012

Perovskite structured barium titanate particles ($BaTiO_3$) platelets were synthesized by molten salt synthesis and topochemical microcrystal conversion. As the precursors of $BaTiO_3$, plate-like $BaBi_4Ti_4O_{15}$ particles were first synthesized by the reaction of $Bi_4Ti_3O_{12}$, $BaCO_3$, and $TiO_2$ at $1080^{\circ}C$ for 3 h in $BaCl_2$-KCl molten salt. After the topochemical reactions, layer-structured $BaBi_4Ti_4O_{15}$ particles transformed to the perovskite $BaTiO_3$ platelets. $BaTiO_3$ particles with thickness of approximately $0.5{\mu}m$ and a length of $10-15{\mu}m$ retained the morphology feature of the $BaBi_4Ti_4O_{15}$ precursor. For <001> $Pb(Mg_{1/3}Nb_{2/3})O_3-32.5PbTiO_3$ (PMNT)-5 wt % PbO piezoelectric ceramics textured with 5 vol % of $BaTiO_3$ templates, the Lotgering factor reached 0.82, and $d_{33}$ was 870 pC/N.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 춘계학술회의 초록집
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• pp.11-11
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• 2010

In order to design for nano structured materials with enhanced thermoelectric properties, the alloys in the pseudo-binary $Bi_2Te_3$-PbTe system were investigated for their micro structure and thermal properties. For this synthesis the liquid alloys were cooled by water quenching method. The micro structure images were taken by using electron probe micro analyzer (EPMA). Dendritic and lamellar structures were clearly observed with the variation in the composition ratio between $Bi_2Te_3$ and PbTe. It was confirmed that a metastable compounds is $PbBi_2Te_4$ in the The $Bi_2Te_3$-PbTe system. The change in the composition increasing $Bi_2Te_3$ ratio causes to change structure from dendritic to lamellar. Seebeck coefficient of alloys 5 which the mixture rate of $Bi_2Te_3$ is 83% was measured as the highest value. In contrast, the others decreased by increasing $Bi_2Te_3$. n-type characteristics was observed at all condition except alloy 6 which $Bi_2Te_3$ ration is 91%. The power factors of all samples were calculated with Seebeck coefficient and resistivity. Also the thermal conductivity was measured by using laser flash analyzer (LFA). In this work, the microstructures and thermal properties have been measured as a function of ratio of $Bi_2Te_3$ in the $Bi_2Te_3$-PbTe system.

• 한국전기전자재료학회논문지
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• 제23권6호
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• pp.502-507
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• 2010

In order to design nano structured materials with enhanced thermoelectric properties, the alloys in the pseudo-binary $Bi_2Te_3$-PbTe system are investigated for their micro structure properties. For this synthesis, the liquid alloys are cooled by the water quenching method. Micro structure images are obtained by using an electron probe micro analyzer(EPMA). Dendritic and lamellar structures are clearly observed with the variation in the composition ratio between $Bi_2Te_3$ and PbTe. The increase in the $Bi_2Te_3$ composition ratio causes to change of the structure from dendritic to lamellar. The Seebeck coefficient of sample 5, in which the mixture rate of $Bi_2Te_3$ is 83%, is measured as the highest value. In contrast, the others decrease with the increase of the $Bi_2Te_3$ composition ratio. Meanwhile, p-type characteristics are observed in sample 6, at 91%-$Bi_2Te_3$ mixture rate. The power factors of the all samples are calculated with the Seebeck coefficient and resistivity.

• 한국통신학회논문지
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• 제31권1C호
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• pp.14-19
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• 2006

LDPC 부호의 높은 부호화 복잡도는 구조적인 패리티 검사 행렬의 설계로 해결할 수 있다. 패리티 검사 행렬을 같은 유형의 블록으로 구성한다면 복호화기의 구현이 간단해지고 구조적 복호화가 가능하며 LDPC 부호를 저장하는데 필요한 메모리를 줄일 수 있는 장점이 있다. 본 논문에서는 부행렬 단위의 girth 조건과 PEG 알고리즘, 비트 노드의 connectivity를 이용하여 부행렬이 순환행렬이나 영행렬로 구성되는 짧은 길이를 갖는 구조적 LDPC 부호의 생성 알고리즘을 제안하였다. 이 알고리즘으로 생성된 부호는 구조적 제한이 없이 생성된 부호에 비하여 낮은 SNR에서는 비슷한 성능을, 높은 SNR에서는 더 좋은 성능을 내는 것을 모의 실험을 통해 확인하였다.

• 한국전산유체공학회지
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• 제21권1호
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• pp.36-42
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• 2016

One of the obstacles on the grid generation for complex geometries with multi-block structured grids is the domain decomposition. In this paper, the domain decomposition for two-dimensional flow is studied using the flow characteristics. The potential flow equation with the source distribution on the panel surface is solved to extract the information of the flow. The current approach is applied to a two-dimensional cylinder and Bi-NACA0012 problems. The generated grids are applied to generic flow solvers and reasonable results are obtained. It can be concluded that the current methods is useful in the domain decomposition for the multi-block structured grid.