• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 C
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• pp.1512-1515
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• 1996

Dense $SiC-ZrB_2$ electro-conductive ceramic composites were obtained by hot pressing for high temperature structural application. The influences of the $ZrB_2$ additions an the mechanical and electrical properties of $SiC-ZrB_2$ composites were investigated. Samples were prepared by adding 15, 30, 45 vol.% $ZrB_2$ particles as a second phase to a SiC matrix. Sintering of monolithic SiC and $SiC-ZrB_2$ composites were achieved by hot pressing under a $10^{-4}$ torr vacuum atmosphere from 1000 to $2000^{\circ}C$ with a pressure of 30 MPa and held for 60 minutes at $2000^{\circ}C$. SiC and $SiC-ZrB_2$ samples obtained by hot pressing were fully dense with the relative densities over 99%. Flexural strength and fracture toughness of the samples were improved with the $ZrB_2$ contents. In the case of SiC sample containing 30vol.% $ZrB_2$, the flexural strength and fracture toughness showed 45% and 60% increase, respectively compared to those of monolithic SiC sample. The electrical resistivities of $SiC-ZrB_2$ composites were measured utilizing the four-point probe method and they decreased significantly with Increasing $ZrB_2$ contents. The resistivity of SiC-30vol.% $ZrB_2$ showed $6.50{\times}10^{-4}{\Omega}{\cdot}cm$.

• 한국재료학회지
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• 제20권4호
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• pp.217-222
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• 2010

Zirconium diboride (ZrB2) and mixed diboride of (Zr0.7Ta0.3)B2 containing 30 vol.% silicon carbide (SiC) composites were prepared by hot-pressing at $1800^{\circ}C$. XRD analysis identified the high crystalline metal diboride-SiC composites at $1800^{\circ}C$. The TaB2 addition to ZrB2-SiC showed a slight peak shift to a higher angle of 2-theta of ZrB2, which confirmed the presence of a homogeneous solid solution. Elastic modulus, hardness and fracture toughness were slightly increased by addition of TaB2. A volatility diagram was calculated to understand the oxidation behavior. Oxidation behavior was investigated at $1500^{\circ}C$ under ambient and low oxygen partial pressure (pO2~10-8 Pa). In an ambient environment, the TaB2 addition to the ZrB2-SiC improved the oxidation resistance over entire range of evaluated temperatures by formation of a less porous oxide layer beneath the surface SiO2. Exposure of metal boride-SiC at low pO2 resulted in active oxidation of SiC due to the high vapor pressure of SiO (g), and, as a result, it produced a porous surface layer. The depth variations of the oxidized layer were measured by SEM. In the ZrB2-SiC composite, the thickness of the reaction layer linearly increased as a function of time and showed active oxidation kinetics. The TaB2 addition to the ZrB2-SiC composite showed improved oxidation resistance with slight deviation from the linearity in depth variation.

• 한국콘텐츠학회논문지
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• 제12권5호
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• pp.404-414
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• 2012

최근 확대되고 있는 여행사간 B2B2C 거래에 있어서, 여행사간 힘의 불균형으로 인하여 가맹점은 도매여행사와의 거래에 있어 거래공정성의 영향을 받고 있다. 따라서 본 연구는 여행업의 발전적 방향을 제시하기 위하여, 여행사간 거래공정성이 가맹여행사의 관계지향성과 성과에 미치는 영향을 검증하기 위하여 실증분석을 실시하였다. 여행사간 B2B 거래에 있어 가맹여행사의 재무, 비재무적 성과에 가장 큰 영향을 미치는 것은 관계지향성이며, 관계지향성에 가장 큰 영향을 미치는 거래여행사의 공정성은 상호작용공정성과 절차공정성 순으로 나타났다. 따라서 여행사간 장기적인 관계지향성에 영향을 미치는 상호작용공정성과 절차공정성의 구성요소인 거래여행사 직원들의 정확한 정보제공 능력과 가맹여행사에 대한 긴밀한 유대관계 유지 능력이 가장 중요한 요인임을 반영하여 상호 win-win할 수 있는 파트너십을 유지하는 것이 중요하다 하겠다.

• Progress in Superconductivity
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• 제10권1호
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• pp.40-44
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• 2008

A combined process of a mechanical ball milling and liquid glycerin ($C_{3}H_{8}O_3$) treatment of boron (B) powder has been conducted to enhance the superconducting properties of $MgB_2$. The individual aims of the mechanical milling and the glycerin treatment were to reduce the grain size of the $MgB_2$ and to achieve homogeneous carbon (C) incorporation into the $MgB_2$, respectively. Four kinds of B powders of as-received, glycerin treated, 2 h milled, and 2 h milled + glycerin treated were prepared. $MgB_2$ bulks were fabricated by in situ process using the prepared B powders. The mechanical ball milling was effective for a grain refinement, and a lattice disorder was easily achieved by glycerin addition. It was found that the critical current density ($J_c$) values were enhanced in the samples with milled B or glycerin treated B only. In the $MgB_2$ bulk prepared with both milled and glycerin treated B, the $J_c$ was further increased due to a higher grain boundary density and a greater C substitution.

• 전기학회논문지
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• 제58권4호
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• pp.770-776
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• 2009

The composites were fabricated by adding 0, 15, 30, 45[vol.%] $ZrB_2$ powders as a second phase to SiC matrix. The physical, mechanical and electrical properties of electroconductive SiC ceramic composites by spark plasma sintering(SPS) were investigated. Reactions between ${\beta}$-SiC and $ZrB_2$ were not observed in the XRD and the phase analysis of the electroconductive SiC ceramic composites. The relative density of mono ${\beta}$-SiC, ${\beta}$-SiC+15[vol.%]$ZrB_2$, ${\beta}$-SiC+30[vol.%]$ZrB_2$ and ${\beta}$-SiC+45[vol.%]$ZrB_2$ composites are respectively 99.24[%], 87.53[%], 96.41[%] and 98.11[%] Phase analysis of the electroconductive SiC ceramic composites by XRD revealed mostly of ${\beta}$-SiC, $ZrB_2$ and weakly of $ZrO_2$ phase. The flexural strength showed the lowest of 114.44[MPa] for ${\beta}$-SiC+15[vol.%]$ZrB_2$ powders and showed the highest of 210.75[MPa] for composite no added with $ZrB_2$ powders at room temperature. The trend of the mechanical properties of the electroconductive SiC ceramic composites is accorded with the trend of the relative density. The electrical resistivity of the electroconductive SiC ceramic composites decreased with increased $ZrB_2$ contents. The electrical resistivity of mono ${\beta}$-SiC, ${\beta}$-SiC+15[vol.%]$ZrB_2$, ${\beta}$-SiC+30[vol.%]$ZrB_2$ and ${\beta}$-SiC+45[vol.%]$ZrB_2$ composites are respectively $4.57{\times}10^{-1},\;2.13{\times}10^{-1},\;2.68{\times}10^{-2}\;and\;1.99{\times}10^{-2}[{\Omega}{\cdot}cm]$ at room temperature. The electrical resistivity of mono ${\beta}$-SiC and ${\beta}$-SiC+15[vol.%]$ZrB_2$ are negative temperature coefficient resistance(NTCR) in temperature ranges from $25[^{\circ}C]\;to\; 100[^{\circ}C]$. The electrical resistivity of ${\beta}$-SiC+30[vol.%]$ZrB_2$ and ${\beta}$-SiC+45[vol.%]ZrB_2$ are positive temperature coefficient resistance(PTCR) in temperature ranges from $25[^{\circ}C]\;to\;100[^{\circ}C]$. It is convinced that ${\beta}$-SiC+30[vol.%]$ZrB_2$ composites by SPS for heater or ignitors can be applied.

• Tuberculosis and Respiratory Diseases
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• 제62권1호
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• pp.43-50
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• 2007

배경 및 목적: 인체암에서 C-erbB-2의 과발현에 대한 광범위한 연구가 시행되고 있지만, 임상적 의의에 대해서는 논란의 대상이 되고 있다. 악성종양에서 신생혈관형성은 암의 진행에 필수적인 요소이다. 본 연구에서는 비소세포 폐암에서 C-erbB-2의 과발현의 의미, 암조직의 신생혈관형성에 중요한 역할을 하는 VEGF의 발현 및 두 표지자의 연관성을 연구하였다. 방 법: 파라핀 포매된 95예의 비소세포 폐암조직을 이용하여 avidin-biotin complex 법에 의한 면역조직화학적 염색을 시행하였으며, 연구재료는 원발성 편평세포암종 60예 그리고 원발성 선암종 35예를 대상으로 하였다. 결 과: 비소세포 폐암에서 선암종의 C-erbB-2의 과발현은 편평세포암종보다 의미 있게 높게 나타났다. 임상병기에 따른 C-erbB-2와 VEGF의 과발현은 진행암에서 증가하는 경향을 나타내었으나, 초기암과의 유의한 차이는 없었다. 선암종에서 C-erbB-2와 VEGF의 발현은 유의하게 상관성을 나타내었다. 결 론: 비소세포 폐암에서 C-erbB-2의 과발현은 암의 유형에 따라 다르다는 것을 알 수 있었으며, C-erbB-2의 과발현이 높게 나타나는 선암종에서는 이 성적과 암세포의 VEGF의 발현이 상관성을 나타낸다는 것을 알 수 있었다.

• Journal of Electrical Engineering and Technology
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• 제5권2호
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• pp.342-351
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• 2010

The SiC-$ZrB_2$ composites were fabricated by combining 30, 35, 40, 45 and 50 vol. % of zirconium diboride ($ZrB_2$) powders with silicon carbide (SiC) matrix. The SiC-$ZrB_2$ composites and the sintered compacts were produced through spark plasma sintering (SPS) under argon atmosphere, and its physical, electrical, and mechanical properties were examined. Also, the thermal image analysis of the SiC-$ZrB_2$ composites was examined. Reactions between $\beta$-SiC and $ZrB_2$ were not observed via x-ray diffraction (XRD) analysis. The apparent porosity of the SiC+30vol.%$ZrB_2$, SiC+35vol.%$ZrB_2$, SiC+40vol.%$ZrB_2$, SiC+45vol.%$ZrB_2$ and SiC+50vol.%$ZrB_2$ composites were 7.2546, 0.8920, 0.6038, 1.0981, and 10.0108%, respectively. The XRD phase analysis of the sintered compacts demonstrated a high phase of SiC and $ZrB_2$. Among the $SiC+ZrB_2$ composites, the SiC+50vol.%$ZrB_2$ composite had the lowest flexural strength, 290.54MPa, the other composites had more than 980MPa flexural strength except the SiC+30vol.%$ZrB_2$ composite; the SiC+40vol.%$ZrB_2$ composite had the highest flexural strength, 1011.34MPa, at room temperature. The electrical properties of the SiC-$ZrB_2$ composites had positive temperature coefficient resistance (PTCR). The V-I characteristics of the SiC-$ZrB_2$ composites had a linear shape in the temperature range from room to $500^{\circ}C$. The electrical resistivities of the SiC+30vol.%$ZrB_2$, SiC+35vol.%$ZrB_2$, SiC+40vol.%$ZrB_2$ SiC+45vol.%$ZrB_2$ and SiC+50vol.%$ZrB_2$ composites were $4.573\times10^{-3}$, $1.554\times10^{-3}$, $9.365\times10^{-4}$, $6.999\times10^{-4}$, and $6.069\times10^{-4}\Omega{\cdot}cm$, respectively, at room temperature, and their resistance temperature coefficients were $1.896\times10^{-3}$, $3.064\times10^{-3}$, $3.169\times10^{-3}$, $3.097\times10^{-3}$, and $3.418\times10^{-3}/^{\circ}C$ in the temperature range from room to $500^{\circ}C$, respectively. Therefore, it is considered that among the sintered compacts the SiC+35vol.%$ZrB_2$, SiC+40vol.%$ZrB_2$ and SiC+45vol.%$ZrB_2$ composites containing the most outstanding mechanical properties as well as PTCR and V-I characteristics can be used as an energy friendly ceramic heater or ohmic-contact electrode material through SPS.

• 한국정보시스템학회:학술대회논문집
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• 한국정보시스템학회 2001년도 추계학술대회 발표논문집:차세대 전상거래 시대의 비즈니스전략
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• pp.252-260
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• 2001

전자상거래는 우리나라 뿐 아니라 여러 선진국에서 새로운 비즈니스 환경으로 급속히 개발 되고 있으며, 아울러 기업에게 위협 요인과 동시에 새로운 기회로 다가오고 있다. 본 논문에서는 기존 전자상거래 모델에서 벗어나 쇼핑몰 관련 그룹을 제조. 유통. 생산업체인 공급자(B)그룹과 제품을 공급받아 소비자에게 직접 판매하는 도·소매(B)그룹 그리고 제품을 구매하는 소비자(C)그룹으로 나누고 서로 윈 윈(Win Win) 할 수 있는 효과적인 전자상거래 모델(B2B2C)의 사례를 연구하고자 한다. 이러한 기업 공동 B2B2C 전자상거래 모델을 웹 어플리케이션 전문제작회사인 D개발회사가 본 시스템 솔루션에 2개월을 소요·개발하여 적용한 결과 고객은 온라인-오프라인 상에서 상호적으로 대응 할 수 있었고, 제품에 대한 품질보증 역할을 더할 수 있어 기존 단골 고객을 중심으로 효율적인 수익을 창출 할 수 있는 전자 상거래 모델을 구축하였다. 즉, 기존의 오프라인의 점 조직 형태의 판매망을 통해 온라인 전자상거래와 상호 유기적으로 도움을 줄 수 있다. 이는 B2B2C의 새로운 전자상거래 모델 제시와 더불어 기존고객을 관리할 수 있는 CRM 도입 효과를 가져와 향후 전자상거래를 통한 온라인 유통망형성에 있어 새로운 솔루션 개발의 기반기술이 될 것이다.

• Progress in Superconductivity
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• 제10권1호
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• pp.17-22
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• 2008

We have examined the effect of ball-milling on the superconducting properties of $MgB_2$ doped with C. The ball-milling of pre-reacted $MgB_2$ powder was carried out in dry or wet state using C or diethylenetriamine ($C_{4}H_{13}N_3$) as additives. The diethylenetriamine, whose chemical formula contains no oxygen, was chosen to avoid an excess oxidation during doping. The superconducting transition temperature (Tc) of the ball-milled or doped $MgB_2$ powders was only slightly smaller than that of undoped $MgB_2$. The critical current density (Jc) of the highly ball-milled $MgB_2$ was higher than that of C-doped $MgB_2$. The addition of diethylenetriamine was detrimental to Jc, although Tc was almost unchanged.

• 한국전자통신학회논문지
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• 제3권2호
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• pp.106-111
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• 2008

유비쿼터스 컴퓨팅에서 RFID와 모바일 단말을 융합하는 모바일 RFID 연구는, B2B 서비스 영역에서 B2C 서비스 영역으로 또한 B2B2C에 이르는 서비스를 제공하기 위해 중요한 수단이며 인프라이다. 본 연구에서는 모바일 RFID 단말을 개발하기 위해, 단말의 미들웨어 기능을 제시한다. 이를 위해, 다중 코드 통합 인식 모듈, 판독기 제어 모듈, 코드 해석 모듈, Dispatcher 모듈의 기능을 구분하여 제시한다. 제안된 기능은 EPC/IOS 및 mCode형 태크를 모두 인식할 수 있다. 제안된 기능의 통합 구현을 위해 구현된 Local ODS와 13.56MHz 태그를 판독할 수 있는 모듈을 제시한다.