• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 추계학술대회 논문집 전기물성,응용부문
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• pp.21-23
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• 2005

The electron transport coefficients, the electron drift velocity W, the longitudinal diffusion coefficient $ND_L$ in $C_{3}F_{8}-Ar$ mixture gases were measured by Double shutter drift tube and calculated by multi-term approximation of the Boltzmann equation over the wide E/N range from 0.03 to 100 Td. And an inelastic collision cross sections for $C_{3}F_{8}$ molecular gas were redetermined for quantitative characteristic analysis.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1997년도 추계학술대회 논문집
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• pp.343-346
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• 1997

This paper presents the basic characteristics of Cr thin-film, which were deposited on glass by DC magnetron sputtering. The optimized deposition condition of Cr thin-film strain gauges were input power 7w/cm$^2$and the Ar working pressure was 9mtorr. GF(Gauge Factor), TCR(Temperature Coefficient of Resistance) and TCS(Temperature Coefficient of Sensitivity) of Cr thin-film strain gauges were 5.86, 400 ppm/$^{\circ}C$ and 0 ppm/$^{\circ}C$, respectively.

• 한국진공학회지
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• 제17권5호
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• pp.426-434
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• 2008

고밀도 유도결합 플라즈마 장치의 $SiH_4/O_2/Ar$방전에 대한 공간 평균 시뮬레이터를 제작하였다. 제작된 시뮬레이터는 $SiH_4/O_2/Ar$ 플라즈마 방전에서 발생되는 전자, 양이온, 음이온, 중성종, 그리고 활성종들에 대해 공간 평균한 유체 방정식을 기반으로 하고 있으며, 전자가열 모델은 anomalous skin effect를 고려한 파워 흡수 모델을 적용하여 전자가 흡수하는 고주파 파워량을 결정하였다. 완성된 시뮬레이터에서 RF-파워와 압력 변화에 대한 하전입자, 중성종, 활성종들의 밀도 변화 및 전자 온도 의존성을 계산하였다.

• Bulletin of the Korean Chemical Society
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• 제28권10호
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• pp.1689-1696
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• 2007

Equilibrium molecular dynamics (EMD) simulations are used to evaluate the transport coefficients of argonkrypton mixtures at two liquid states (state A: 94.4 K and 1 atm; state B: 135 K and 39.5 atm) via modified Green-Kubo formulas. The composition dependency of the volume at state A obeys close to the linear model for ideal liquid mixture, while that at state B differs from the linear model probably due to the high pressure. The radial distribution functions for the Ar-Kr mixture (x = 2/3) show a mixing effect: the first peak of g11 is higher than that of g(r) for pure Ar and the first peak of g22 is lower than that of g(r) for pure Kr. An exponential model of engineering correlation for diffusion coefficient (D) and shear viscosity (η) is superior to the simple linear model for ideal liquid mixtures. All three components of thermal conductivity (λpm, λtm, and λti) at state A and hence the total thermal conductivity decrease with the increase of x. At state B, the change in λtm is dominant over those in λpm and λti, and hence the total thermal conductivity decrease with the increase of x.

• Smart Structures and Systems
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• 제11권1호
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• pp.1-17
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• 2013

This paper intended to investigate the feasibility of bridge health monitoring using a linear system parameter of a time series model identified from traffic-induced vibrations of bridges through a laboratory moving vehicle experiment on scaled model bridges. This study considered the system parameter of the bridge-vehicle interactive system rather than modal ones because signals obtained under a moving vehicle are not the responses of the bridge itself but those of the interactive system. To overcome the shortcomings of modal parameter-based bridge diagnosis using a time series model, this study considered coefficients of Autoregressive model (AR coefficients) as an early indicator of anomaly of bridges. This study also investigated sensitivity of AR coefficients in detecting anomaly of bridges. Observations demonstrated effectiveness of using AR coefficients as an early indicator for anomaly of bridges.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.1252-1253
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• 2008

The $V_{1.8}W_{0.2}O_5$ thin films deposited on $Pt/Ti/SiO_2/Si$ substrates by RF sputtering method with different $Ar/O_2$ ratio. The $V_{1.8}W_{0.2}O_5$ thin films were measured electrical and structural properties, fairly good Temperature coefficient of resistance(TCR). It was found that electrical and structural properties, TCR properties of thin films were strongly dependent upon the $Ar/O_2$ ratio. The dielectric constant of the $V_{1.8}W_{0.2}O_5$ thin films with 50/20 ratio were 93 with a dielectric loss of 0.535, respectively. Also, the TCR values of the $V_{1.8}W_{0.2}O_5$ thin films with 50/20 ratio were -3.15%/$^{\circ}C$.

• 전기학회논문지P
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• 제53권2호
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• pp.65-69
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• 2004

This paper calculates and gives the analysis of electron swarm transport coefficients as described electric conductive characteristics of pure Ar, pure $SiH_4$, Ar-$SiH_4$ mixture gases($SiH_4$-0.5%, 2.5%, 5%) over the range of E/N = 0.01~300[Td], P = 0.1, 1, 5.0 [Torr] by Monte Carlo the backward prolongation method of the Boltzmann equation using computer simulation without using expensive equipment. The results have been obtained by using the electron collision cross sections by TOF, PT, SST sampling, compared with the experimental data determined by the other author. It also proved the reliability of the electron collision cross sections and shows the practical values of computer simulation. Electron swann parameters in argon were drastically changed by adding a small amount of mono-silane. The electron drift velocity in these mixtures showed unusual behaviour against E/N. It had negative slope in the medium range of E/N, yet the slope was not smooth but contained a small hump. The longitudinal diffusion coefficient also showed a corresponding feature in its dependence on E/N. A two-tenn approximation of the Boltzmann equation analysis and Monte Carlo simulation have been used to study electron transport coefficients.

• Journal of the Korean Statistical Society
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• 제25권4호
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• pp.529-544
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• 1996

This paper deals with the problem of estimating the autoregressive random coefficient of a first-order random coefficient autoregressive time series model applied to panel data of time series. The autoregressive random coefficients across individual units are assumed to be a random sample from a truncated normal distribution with the space (-1, 1) for stationarity. The estimates of random coefficients are obtained by an empirical Bayes procedure using the estimates of model parameters. Also, a Monte Carlo study is conducted to support the estimation procedure proposed in this paper. Finally, we apply our results to the economic panel data in Liu and Tiao(1980).

• 한국산학기술학회논문지
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• 제16권7호
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• pp.4835-4841
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• 2015

n형 FeSi2의 열전물성에 미치는 입자크기 및 성형압력의 영향에 대해 조사하였다. 입자크기가 다른 출발 분말을 각각 가압성형(성형압력; $70{\sim}220kg/cm^2$) 하였고, 제작한 성형체를 Ar 분위기 1473 K에서 7시간 소결한 후, 반도체상인 ${\beta}$상을 얻기 위해 1103 K에서 100시간 소둔처리 하였다. XRD, SEM 및 EDS를 이용해서 시편들의 미세구조 및 상분석을 행하였다. 동일 시료를 가지고 Ar 분위기 상온~1023 K에서 도전율과 Seebeck 계수를 동시에 측정하였다. 입자크기가 작을수록 소결밀도와 잔존 ${\varepsilon}$-FeSi 금속전도상 증가에 의해 도전율이 상승하였으며, Seebeck 계수는 700~800 K에서 최고값을 나타내었고, 입자크기가 작을수록 잔존 ${\varepsilon}$-FeSi 금속전도상 증가에 의해 감소하였다. 반면에 성형압력의 변화는 도전율 및 Seebeck 계수에 그다지 큰 영향을 미치지 않았다. 결과적으로 power factor는 성형압력 보다 입자크기에 큰 영향을 받았다.

• 한국세라믹학회지
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• 제40권10호
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• pp.991-997
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• 2003

SiC세라믹스의 열전변환물성에 미치는 A1$_4$C$_3$ 첨가효과에 대해 연구하였다. $\alpha$-SiC 분말에 A1$_4$C$_3$를 첨가하여 Ar분위기 2100∼220$0^{\circ}C$에서 3시간 소결하여 상대밀도 47∼59%인 다공질 SiC세라믹스를 제조하였다. X-선 회절분석 및 주사형 전자현미경으로 소결체의 상조성과 미세구조를 분석하였으며, A1$_4$C$_3$ 첨가에 의해 6H에서 4H로의 상전이 발생을 관찰할 수 있었다. 전기전도도와 Seebeck 계수를 Ar 분위기 550∼95$0^{\circ}C$에서 측정하였다. 무첨가 시료의 경우 출발원료중에 함유된 p형 불순물(Al, Fe)에 의해 Seebeck 계수가 정(+)의 값을 나타내었으며, 소결온도가 증가함에 따라 전기전도도가 증가하였다. A1$_4$C$_3$ 첨가 시료의 전기전도도는 상전이 및 캐리어농도 증가에 의해 무첨가 시료보다 높았으며, 또 Seebeck 계수도 크게 나타났다. 시료의 밀도, 첨가량 및 소결조건이 열전변환물성에 크게 기여하였다.