목적: 자유공간과 제한된 공간에서 측정한 Gradient AC/A비를 비교 분석하여 3가지 사위측정법의 신뢰도를 평가하였다. 방법: 2006년 9월 1일부터 2009년 9월 30일까지 서울에 거주하며 본 연구의 취지에 동의한 전신질환과 안질환이 없는 20세 이상의 성인 67명(26.61±2.56세)(남자 32명, 여자 35명)을 대상으로 선정하였으며, 굴절이상 수술 또는 사시 수술 병력이 있는 자는 대상자에서 제외하였다. 자동굴절검사(KR-7100P, Topcon Co.)와 표준 자각식 굴절검사로 원거리 굴절 이상도를 측정하였고, 포롭터(Shin-Nippon BR-7), 시력표투영기(Topcon ACP-7), 시험테(FM580), 렌즈 홀더(Gulden Ophthalmics co.), 프리즘바(Gulden co.), 낱개 프리즘, MIM Card(Bernell co.) 등을 이용하여 본그래페법, 마독스봉 및 수정 토링톤법에 의한 사위도 및 Gradient AC/A비를 측정하였다. 결과: 등가구면 굴절이상도는 우안 -2.79±2.56D, 좌안 -2.69±2.65D였고, 난시도는 우안 -0.80±0.49D, 좌안 -0.93±0.71D였다. 대상자 전체의 사위도는 원거리가 -0.31±1.24△, 근거리가 -1.67±4.51△이었다. 포롭터를 이용한 사위도는 VG(distance) -0.78±2.14△, MR(distance) -0.35±1.85△, MT(distance) -0.40±1.81△, VG(near) -2.63±4.64△, MR(near) -1.69±4.80△, MT(near) -1.78±4.52△이었다. 시험테로 측정된 사위도는 VG(distance) -0.69±1.96△, MR(distance) -0.32±1.77△, MT(distance) -0.40±1.82△, VG(near) -2.31±4.18△, MR(near) -1.60±4.51△, MT(near) -1.68±4.20△이었다. 제한된 공간에서 ±1D를 이용하여 측정한 Gradient AC/A비는 VG 3.32±0.81△, MR 3.07±0.61△, MT 2.74±0.29△이었고 자유공간에서 측정한 Gradient AC/A비는, VG 3.27±0.73△, MR 3.11±0.64△, MT 2.57±0.26△이었다. 각 측정법의 신뢰도를 비교한 결과, 95% 일치구간은 포롭터를 이용한 VG 측정법이 3.04로 가장 넓었고 시험테를 이용한 MT 측정법이 1.42로 가장 좁아 신뢰도가 높았다. 결론: 이상으로부터 제한된 공간과 자유 공간에서 측정된 사위도는 약간의 차이가 있었으나 임상적으로 유의하지 않은 것으로 판단되었고, Gradient AC/A비를 기준했을 때 VG 측정법과 MR 측정법보다는 MT 측정법의 신뢰도가 높은 것으로 사료된다.

The carbon brake discs were manufactured by densification the carbon fiber preform using PG-CVI technology with Propene as a carbon precursor gas and Nitrogen as a carrier gas. The densities of carbon brake discs were tested at different densification time. The results indicate that the densification rate is more rapid before 100 hrs than after 200 hrs. The CTscanning image and the SEM technology were used to observe the inner subtle structure. CT-images show the density distribution in the carbon brake disc clearly. The carbon brake disk made by PG-CVI is not very uniform. There is a density gradient in the bulk. The high-density part in the carbon brake is really located in the friction surface, especially in the part of inner circle. This density distribution is most suitable for the stator disc.

Particles of high strength material when coated with silver offer a means of obtaining desirable electrical properties and high strength. The coating process employed aqueous ammoniacal silver-nitrate electrolytes with a formaldehyde solution as the reductant. Modifying additives were also applied. The reduction and subsequent deposition of silver occurred selectively on the surface of the tungsten particles. The morphologies of the coated particles were assessed by SEM imaging. The silver was uniformed coated on tungsten powder and its thickness was estimated to be approximately 100nm on the basis of a mass account.

The p-type Te functional gradient material (FGM) was fabricated by hot-pressing the mechanically alloyed and the 0.5 at% powders. Also, the n-type FGM was processed by hot-pressing the mechanically alloyed and the 0.3 wt% Bi-doped PbTe powders. With larger than , the p-type FGM exhibited larger thermoelectric output power than those of the and the 0.5 at% alloys. For the n-type FGM, the thermoelectric output power superior to those of the and the 0.3 wt% Bi-doped PbTe was predicted at larger than .

In this study, the diffusion behaviors of C and Co in liquid phase sintering of WC-Co system were investigated whether these two components diffused in the same direction in case of having opposite gradient each other with not being phase. The green compacts with controlled compositions in not being of phase and gradient composition which one is WC-5Co-1.2%C, the other is WC-XCo-0.2%C (where X = 5, 10, 15, 20, 25) were sintered at and and then the diffusion behaviors of C and Co were investigated by analyses of compositional change, also determined for microstructure and microhardness. Also, same testing was carried out on the specimens with dual layers sintered in upright and reverse positions to evaluate the effect of gravity on the diffusion in liquid Co. From the results of this study, we can find the fact that the direction of diffusion for C and Co in WC-Co system during liquid phase sintering was different and the effect of gravity for the liquid was insignificant. Also other physical properties were changed on the diffusion of elements.

시험도로에서 포장구조진단기(FWD)를 사용하여 48시간 동안 연속적으로 온도구배에 따른 콘크리트 포장의 거동을 조사하였다. 포장슬래브의 중앙부에서 측정한 최대 처짐의 경향은 대기온도 및 온도구배와 유사하였으며 오전 8시에서 12시 사이에 매우 급격한 변화를 나타내었다. 동적지지력과 줄눈의 처짐은 대기온도 및 온도구배와 반대되는 경향을 나타내었으며, 동적지지력은 값이 커질수록 온도구배의 영향을 심하게 받는 것으로 판단되었다. 탄성계수의 변화양상을 AREA법과 MET을 사용하여 조사하였다. 역계산된 탄성계수는 동적지지력이 시간에 따라 나타내는 변화와 같은 경향을 나타내었다. 줄눈에서의 하중전달율은 다우웰 바의 잠김 작용으로 인하여 아침에 최대값을 나타내었으며 이와 관련하여 향후 정밀한 조사가 필요한 것으로 판단되었다.

The inverse Compton scattering of the cosmic microwave background (CMB) radiation with electrons in the intracluster medium which has a temperature gradient, was examined by the third-order perturbation theory of the Compton scattering. A new type of the spectrum distortion of the CMB was found and named as gradient T Sunyaev-Zel'dovich effect (gradT SZE). The spectrum has an universal shape. There is a zero distortion point, the cross over frequency, at 326GHz. When the hotter region locates closer to an observer, the intensity becomes brighter than the CMB in the frequency region lower than the cross over frequency and fainter than the CMB in the frequency region higher than the cross over frequency. When the cooler region locates closer to an observer, the distorted part of the spectrum has an opposite sign to the above case. The amplitude of the spectrum distortion does not de-pend on the electron density and depends on the heat conductivity and the total temperature variation along a line of sight. Therefore, the gradT SZE provides an unique opportunity to measure thermally nonequilibrium electron momentum distribution function in the ICM and combined with the X-ray measurements of the electron temperature distribution provides an opportunity of direct measurement of the heat conductivity in the ICM.