• 한국진공학회지
• /
• 제8권1호
• /
• pp.43-50
• /
• 1999

이온빔보조증착법으로 h-BN을 증착하여 이온에너지 및 기판온도에 따른 hexagonal ring의 배열 및 결정성의 변화를 연구하였다. 보론은 전자빔으로 1.5 $\AA$/sec 의 속도로 증발시켰으며, 질소는 둥-hall 형 이온건으로 60, 80, 100eV의 에너지로 공급하였다. 기판의 온도는 상온(no heating), 200, 400, 500, $800^{\circ}C$로 변화시켰다. 질소이온에너지가 증가할수록 hexagonal ring의 c축은 기판에 평행하게 배열하여 100 eV의 질소이온에너지에서 가장 좋은 배열을 나타내었다. 이는 이온에너지가 높을수록 합성 막에 큰 압축응력이 발생하기 때문으로 생각된다. 기판온도에 따라서는 온도가 증가함에 따라 배열이 증가하다가 약 $400^{\circ}C$에서 최대가 되고 그 보다 높은 온도에서는 배열이 감소하였다. 그리고 결정도는 온도가 증가할수록 향상되었다. 이러한 경향들은 온도가 증가함에 따라 원자 이동도는 증가하고 응력발생은 어려워지는 경향으로부터 잘 설명된다. 또한 nano-indentor로 측정한 h-BN막의 경도는 c-축의 배열정도와 같은 경향을 보였다. 이온빔보조증착법은 hexagonal ring의 배열을 통해 h-BN막 성질의 최적화에 효과적인 방법으로 판단된다.

• 건축역사연구
• /
• 제12권3호
• /
• pp.163-179
• /
• 2003

The records of about 60 travel essays of the Hall of Bhaisajyaguru(Healing) Budda which was built in Chung Yang Temple passed down since 1525. The chronological change of that Hall architecture according to each period was traced upon. The building structure of the Hall of Bhaisajyaguru Budda which has a roundabout way, and 6 pillars inside, sometimes each 6 pillars inside and outside is hexagonal, one story building in Japanese colonial period(picture 3-1) or the present(picture 3-3). The panaromic picture of Chung Yang Temple shows no alterations of the layout of buildings(picture 1-1), in which the Hall of $Praj{\tilde{n}}{\bar{a}}$(般若殿), the main building in the center and the Hall of Bhaisajyaguru(Healing) Budda, three story stone pagoda, stone lighthouse in front of it became the central axis. The Hall of Bhaisajyaguru(Healing) Budda remained as it was until Japanese invasions in 1592 and 1597. However, it was greatly damaged by the flood in 1717. It was newly built by Lee Ha Gon's leading in 1717-1732. At that time, the interior design was changed. With Bhaisajyaguru(Healing) Budda, 53 Buddhas and ${\acute{S}}arira$ of Stone stupa which show itself by the flood in 1717 was located in the image of the Mountain of Chunchuk or Cheontae like Yu Jeom Temple. The doors of this Hall are located in the front and back. In the four walls each, two realistic and cubic buddhism pictures were drawn, The color of those picture was partly taken off in 1671 and repainted in 1714. The new building in 1717-1732 regained its colorful appearance. However, the names written beside each Images of Buddha disappeared. The notable remark in these records is that some of these travel essays in 17th-18th centuries was calling this hexagonal hall as the octagonal one. It is very important records because it means that before 1525 the octagonal hall might have existed. Chung Yang Temple was rebuilt between 1976 and 1985 after the destruction in the Korean War. After the records are carefully read, the full scale excavation about this historic site was not done yet. The interesting issue of the existence of octagonal building will be resolved by the full scale excavation.

• 한국세라믹학회지
• /
• 제54권6호
• /
• pp.506-510
• /
• 2017

One of the characteristics of polycrystalline graphene that determines its material properties is grain size. Mechanical properties such as Young's modulus, yield strain and tensile strength depend on the grain size and show a reverse Hall-Petch effect at small grain size limit for some properties under certain conditions. While there is agreement on the grain size effect for Young's modulus and yield strain, certain MD simulations have led to disagreement for tensile strength. Song et al. showed a decreasing behavior for tensile strength, that is, a pseudo Hall-Petch effect for the small grain size domain up to 5 nm. On the other hand, Sha et al. showed an increasing behavior, a reverse Hall-Petch effect, for grain size domain up to 10 nm. Mortazavi et al. also showed results similar to those of Sha et al. We suspect that the main difference of these two inconsistent results is due to the different modeling. The modeling of polycrystalline graphene with regular size and (hexagonal) shape shows the pseudo Hall-Petch effect, while the modeling with random size and shape shows the reverse Hall-Petch effect. Therefore, this study is conducted to confirm that different modeling is the main reason for the different behavior of tensile strength of the polycrystalline structures. We conducted MD simulations with models derived from the Voronoi tessellation for two types of grain size distributions. One type is grains of relatively similar sizes; the other is grains of random sizes. We found that the pseudo Hall-Petch effect and the reverse Hall-Petch effect of tensile strength were consistently shown for the two different models. We suspect that this result comes from the different crack paths, which are related to the grain patterns in the models.

• 환경위생공학
• /
• 제21권4호
• /
• pp.77-86
• /
• 2006

The water purification was very important in Korea which has not sufficient water resource and while adsorption method among the various methods to eliminate the water pollutants has been widely used by activated carbon. This study was conducted the basic experiment for hall distribution, pH, conductivity, electronic microscope, cation exchange and inorganic materials the adsorption capacity of Korean traditional charcoal which has similar characteristics to activated carbon of organic pollutants. As a result of observing Korean traditional charcoal with electronic microscope, it was found that it has porous structure, oak charcoal has circular structure, pine charcoal has square structure and bamboo charcoal has hexagonal structure, which has high void fraction per unit area because of its thin cell wall structure. As a result of experimenting hall distribution, hall distribution of bamboo high temperature charcoal is high as 0.269cc/g and has the greatest inorganic contents and cation exchange capacity(CEC) which are the important factor of chemical adsorption.

• 한국진공학회지
• /
• 제1권1호
• /
• pp.126-133
• /
• 1992

E-Beam 기법을 이용하여 증착시킨 Ag doped CdS 박막은 육방정계이고 공기, Ar 분위기에서 $^550{\circ}C$로 열처리한 결과 grain size가 1$mu extrm{m}$ 정도로 성장되었고, Van Der Pauw 방법으로 구한 Hall data로부터 CdS crystal은 n형 반도체이고 상온에서의 carrier 농 도는 2.7 $\times$ 1011cm-3이고 Hall mobility는 5.8 $\times$ 102cm2V-1sec-1정도임을 알 수 있었다. CdS : Ag 박막의 PL spectra는 Gaussian curve를 보여주었고, spectra peak는 파장이 520nm 근처에 위치하고 있으며, CdS : Ag 박막에서의 광전류(pc)와 암전류(dc)의 ratio(pc/dc)는 공기 중에서 열처리한 시료의 값이 크다는 것을 알 수 있었다.

• 한국결정학회지
• /
• 제8권2호
• /
• pp.105-110
• /
• 1997

CdS/CuInSe2 태양전지에서 창측재료로 1μm 두께의 CdS박막을 1x10-3mTorr의 진공하에서 CdS source 온도를 800-1100'C로 하고 기판의 온도를 50-200℃로하여 진공증차겁으로 제조하였다. 증착된 CdS박막의 구조적, 전기적, 광학적 특성조사는 x-ray diffractometer(XRD), scanning electron microscope(SEM), 전기비저항 측정, Hall measurement 그리고 optical transmission spectra로 행하였고, 각막들의 성분분석은 energy dispersive analysis of X-ray (EDAX)를 가하나, 광투과도는 감소하였다. 이때 증착된 CdS 박막들은 모두 hexagonal 구조를 가지고 있었으며, 결정성은 기판유리를 딸 (002)면으로 형성되었다. CdS Source 온도가 1000℃에서 증착된 CdS 박막이 0.9(S/cm)의 가장 높은 전기 전도도를 나타내었다. 또한 기판온도를 100'C로 제조한 CdS 박막이 전기비저항은 40(Ω,cm)이었고 광투과도는 80% 이상의 값을 나타내어 CdS/CuInSe2 태양전지의 창측재료로 적합했다.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
• /
• pp.180-181
• /
• 2006

CdSe single crystal was grown by sublimation method in the two-step vertical electric furnace. This CdSe single crustal had hexagonal structure whose lattice constants of $a_0$ and $c_0$ were measured $4.299\;{\AA}$ and $7.009\;{\AA}$ by extrapolation method, respectively. CdSe single crystal was n-type semiconductor values were measured from Hall data by Van der Pauw method in the room temperature. Mobility tends to increase in proportion to $T^{3/2}$ from 33K to 130K due to impurity scattering. but mobility tends to decrease in proprtion to $T^{-3/2}$ from 130K to 293K due to lattice scattering. CdSe thin film was made by electron beam evaporation technique had also hexagonal structure. The grain size of this thin film was grown to $1{\mu}m$ as a result of annealing in the vapor of Ar or Cd. Annealde CdSe thin film was n-type semiconductor whose carrier density had about $7{\times}10^{12}cm^{-3}$ and its mobility had about $1.6{\times}10^3cm^2/V$ sec at room temperature.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2004년도 춘계학술대회 논문집 반도체 재료 센서 박막재료 전자세라믹스
• /
• pp.1-4
• /
• 2004

Polycrystalline CdSe thin films were grown on ceramic substrate using a chemical bath deposition(CBD)method. They were annealed at various temperature and X-ray diffraction patterns were measured by X-ray diffractometer in order to study CdSe polycrystal structure. Using extrapolation method of X-ray diffraction patterns for the CdSe samples annealed in $N_2$ gas at $450^{\circ}C$ it was found hexagonal structure whose lattice parameters $a_0$ and $c_0$ were $4.302{\AA}$ and 7.014 ${\AA}$, respectively. Its grain size was about 0.3 ${\mu}m$. Hall effect on this sample was measured by Van der Pauw method and studied on carrier density and movility depending on temperature. From Hall data, the mobility was likely to be decreased by piezo electric scattering at temperature range of 33K and 200K, and by polar optical scattering at temperature range of 200K and 293K. We measured also spectral response, sensitivity$(\gamma)$, maximum allowable power dissipation and response time on these samples.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 1991년도 추계학술대회 논문집
• /
• pp.12-16
• /
• 1991

Cadmium sulphide films with thickness of 0.6∼1.2$\mu\textrm{m}$ were deposited onto corning 7059 glass substrate under a vacuum of 5${\times}$10$\^$-6/ Torr. Source and substrate temperature ranges used were 800∼1100$^{\circ}C$ and 100∼200$^{\circ}C$, respectively. The microstructures and semiconducting properties of the films were studied using X-ray diffraction, UV-VIS-IR spectrophotometer and Hall measurement unit. Electrical resistivity and optical transmission of the CdS films decrease with an increase in source temperature while they increase with an increase in substrate temperature. The resistivity of the film evaporated at 1100$^{\circ}C$ varied from 7${\times}$10$^3$ohm-cm at the substrate temperature of 100$^{\circ}C$ to 2${\times}$10$\_$6/ohm-cm at 190$^{\circ}C$. All the films had hexagonal structure and strong texture with c-axis of grains normal to the substrate glass.

• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.II
• /
• pp.1542-1545
• /
• 2005

Transparent conducting aluminum-doped zinc oxide (AZO) thin films have been deposited on corning 1737 glass by DC magnetron sputter. The structural, electrical and optical properties of the films were investigated as a function of various substrate temperatures. AZO thin films were fabricated by dc magnetron sputtering with AZO ceramic target $(Al_2O_3: 2wt %)$. The obtained films were poly crystalline with a hexagonal wurtzite structure and preferentially oriented in the (002) crystallographic direction. The lowest resistivity is $6.0{\times}10^{-4}$ Ocm with the carrier concentration of $2.694{\times}10^{20}\;cm^{-3}$ and Hall mobility of $20.426cm^2/Vs$. The average transmittance in the visible range was above 90%.