• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 1997년도 춘계학술대회 논문집
• /
• pp.338-341
• /
• 1997

According to reports, it is impossible to make Ohmic Contact with high resistivity p type CdTe or CdZnTe semiconductor theoretically. But it is in need of making Ohmic Contact to fabricate semiconductor radiation detector By electroless deposition method using gold chloride solution, we made Ohmic Contact of Au and p-Cd$_{80}$Zn$_{20}$Te which grown by High Presure Bridgman Method in Aurora Technologies Corporation. We investigated the interface with Rutherford Backscattering Spectrometry and Auger electron spectroscopy. And we evaluated the degree of Ohmic Contact for the Au/CdZnTe interface by the I/V characteristic curve. As a result, we concluded that it showed excellent Ohmic Contact property by tunneling mechanism through the interface.e.

• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
• /
• pp.66.1-66.1
• /
• 2010

Microcrystalline silicon at low temperatures has been developed using plasma enhanced chemical vapor deposition (PECVD). It has been found that energetically positive ion and atomic hydrogen collision on to growing surface have important effects on increasing growth rate, and atomic hydrogen density is necessary for the increasing growth rate correspondingly, while keeping ion bombardment is less level. Since the plasma potential is determined by working pressure, the ion energy can be reduced by increasing the deposition pressure of 700-1200 Pa. Also, correlation of the growth rate and crystallinity with deposition parameters such as working pressure, hydrogen flow rate and input power were investigated. Consequently an efficiency of 7.9% was obtained at a high growth rate of 0.92 nm/s at a high RF power 300W using a plasma-enhanced chemical vapor deposition method (27.12MHz).

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 1997년도 춘계학술대회 논문집
• /
• pp.743-747
• /
• 1997

Polishing work for a curved surface die demands simple and repetitive operations and requires much time while it also demands high precision. Therefore it is operated by skilled worker in handiwork. Howener workers avoid polishing work gradually because of the poor environments such as dust and noise. In order to reduce the polishing time and to alleviate the problem of shortage of skilled workers, researches for automation of polishing have been pursued in the developed countries. In the research, a polishing robot with 2 degrees of freedom motion attached to machining center with 3 degrees of freedom and pneumatic system forms an automatic polishing system which keeps the polishing tool vertically on the surface of die and maintains constant pneumatic pressure. A synchronization between machining center and polishing robot is accomplished by using M code of machining center. A rulled surface and shadow mask are polished by the developed polishing robot.

• Journal of Preventive Medicine and Public Health
• /
• 제20권2호
• /
• pp.221-227
• /
• 1987

In vivo ethane production in rats was used as an index of oxygen toxicity. The rats were allocated to four exposure conditions; hyperbaric oxygenation (HBO=5 ATA, 100% $O_2$), normobaric oxygenation (NBO=1 ATA,100% $O_2$), hyperbaric aeration (HBA=5 ATA, 21% $O_2$) and normobaric aeration (NBA=1 ATA, 21% $O_2$). After 120 minutes of exposure, the rats exposed to high concentration and/or high pressure oxygen exhaled significantly larger amounts of ethane than those exposed to NBA, and the differences in ethane production between any two groups were statistically significant (p<.01). This finding supports the hypothesis that hyperoxia increases oxygen free-radicals and the radicals produce ethane as a result of lipid peroxidation. It is notable that the ethane exhalation level of the HBA group was significantly higher than that of the NBO group. This difference could not be accounted for by the alveolar oxygen partial presure difference between the two groups.

• 대한기계학회논문집B
• /
• 제25권6호
• /
• pp.776-785
• /
• 2001

Hot-wire measurements are performed in boundary layers developing on a NACA0012 airfoil over which wakes pass periodically. The Reynolds number based on chord length of the airfoil is 2$\times$10(sup)5 and the wakes are generated by circular cylinders rotating clockwise and counterclockwise around the airfoil. This paper and its companion Part II describe the phenomena of wake-induced transition of the boundary layers on the airfoil using measured data; phase-and time-averaged streamwise mean velocities, turbulent fluctuations, integral parameters and wall skin frictions. This paper describes the background and facility together with results of time-averaged quantities. Due to the passing wake with mean velocity defects and high turbulence intensities, the laminar boundary layer is periodically disturbed at the upstream station and becomes steady-state transitional boundary layer at the downstream station. The velocity defect in the passing wake changes the local pressure at the leading of the airfoil, significantly affects the time-mean pressure distribution on the airfoil and eventually, has influence on the transition process of the boundary layer.

• 한국대기환경학회지
• /
• 제12권4호
• /
• pp.389-398
• /
• 1996

In order to understand the relative importance of various pathways leading to the production and transformation of aerosols under different atmospheric conditions, the behavior of atmospheric aerosols have been investigated using a high volume tape sample in Seoul for a week period during August 1990. The concentrations of anion $(SO^{2-}_4, NO^-_3, CI^-)$ and cation $(Ca^{2+}, Na^+, NH^+_4)$ species of aerosol samples were analyzed to identify the ionic composition of aerosols and to estimate their relative contributions to aerosol formation. The concentrations of aerosol species were calculated by a multiple regression model. The results of our calculations indicate the existence of various chemical species such as $(NH_4)_2SO_4, Na_2SO_4, CaSO_4, NH_4NO_3, NaNO_3, Ca(NO_3)_2, NH_4Cl$, and NaCl salts. According to our calculations, the most dominant species of aerosol was $(NH_4)_2SO_4$ with the mean concentration of 23.3 $/mu g/m^3$ (66.9%). The proportion of different componts with aerosol (e.g., $NH_4NO_3$ and $NH_4Cl$) was strongly affected by temperature, relative humidity, and partial presure of gases.

• 한국가스학회지
• /
• 제7권2호
• /
• pp.48-53
• /
• 2003

에너지 관련 플랜트에 사용되는 배관은 플랜트의 성능이나 안전성유지에 있어서 중요한 설비의 일부이다. 본 연구에서는 고압탄소강 배관의 변형 및 파괴에 대한 음향방출 기초 자료를 얻기 위하여 압력용기용 배관재를 기계가공하여 인장시험편을 만든 후, 인장시험을 실시하여 항복, 소성변형 및 파괴에 이르기까지의 음향방출 신호를 분석하였다. 탄성영역, 최대인장강도 이전의 소성영역 및 최대인장강도 이후의 소성영역에서 검출된 음향방출의 시간-주파수 분석 결과는 탄성영역에서 항복영역까지는 비교적 낮은 저주파수 대역(250${\~}$350kHz)이 나타났으며, 소성영역에서는 저주파수뿐만 아니라 고주파수 대역(500kHz)도 나타났다. 인장시험 후, 이러한 각 영역의 구별이 가능하였던 원인은 항복영역에서의 전위의 이동, 집적에 따른 신호와 최대인장강도 이전의 소성영역에서의 전위들이 개재물이나 결정입계를 통과했을 때 나타나는 신호, 최대인장강도 이후에는 미소공동의 발생, 성장 및 합체에 의하여 나타나는 신호로 분류가 가능하였기 때문인 것으로 판단된다.

• 한국콘텐츠학회논문지
• /
• 제12권12호
• /
• pp.363-371
• /
• 2012

본 연구는 당뇨환자와 일반인을 대상으로 $VO_2peak$가 복부둘레, 혈중지질 및 혈압에 어떠한 영향을 미치는지 알아본 결과 당뇨환자인 경우 $VO_2peak$와 복부둘레에서 부적상관을 나타냈으며 유의한 차이가 나타났다. 고밀도 지단백 콜레스테롤은 정적상관을 보였으며 유의한 차이가 나타났다. 일반인의 $VO_2peak$와 이완기혈압에서는 정적상관을 보였으며 유의한 차이가 나타났다. 당뇨환자의 복부둘레에서 $VO_2peak$에 통계적으로 유의한 영향을 미치는 것으로 나타났으며, 일반인의 이완기 혈압에서 $VO_2peak$에 통계적으로 유의한 영향을 미치는 것으로 나타났다. 또한 집단 간 복부둘레, $VO_2peak$, 고밀도 지단백 콜레스테롤, 중성지방, 혈압에서 집단 간 유의한 차이가 나타났다. 따라서 유산소능력($VO_2peak$) 지표들을 모니터링 함으로써 당뇨 환자들은 심혈관 질환의 위험요인을 관리할 수 있을 것으로 보인다. 또한 유산소능력을 향상시키는 운동을 실시하는 것 역시 심혈관 질환의 위험도를 낮추기 위한 좋은 방안이라고 사료된다.

• 한국농공학회지
• /
• 제35권2호
• /
• pp.43-56
• /
• 1993

The laboratory tests are performed on how the liquefaction potential of the sea dike structures on the saturated sand or silty sand seabed could be affected due to earthquake before and after construction results are given as follows ; 1. Earthquake damages to sea dike structures consist of lateral deformation, settlement, minor abnormality of the structures and differential settlement of embankments, etc. It is known that severe disasters due to this type of damages are not much documented. Because of its high relative cost of the preventive measures against this type of damages, the designing engineer has much freedom for the play of judgement and ingenuity in the selection of the construction methods, that is, by comparing the cost of the preventive design cost at a design stage to reconstruction cost after minor failure. 2. The factors controlling the liquefaction potential of the hydraulic fill structure are magnitude of earthquake(max. surface velocity), N-value(relative density), gradation, consistency(plastic limit), classification of soil(G & vs), ground water level, compaction method, volumetric shear stress and strain, effective confining stress, and primary consolidation. 3. The probability of liquefaction can be evaluated by the simple method based on SPT and CPT test results or the precise method based on laboratory test results. For sandy or silty sand seabed of the concerned area of this study, it is said that evaluation of liquefaction potential can be done by the one-dimensional analysis using some geotechnical parameters of soil such as Ip, Υt' gradation, N-value, OCR and classification of soils. 4. Based on above mentioned analysis, safety factor of liquefaction potential on the sea bed at the given site is Fs =0.84 when M = 5.23 or amax= 0.12g. With sea dike structures H = 42.5m and 35.5m on the same site Fs= 3.M~2.08 and Fs = 1.74~1.31 are obtained, respectively. local liquefaction can be expected at the toe of the sea dike constructed with hydraulic fill because of lack of constrained effective stress of the area.

• 자원환경지질
• /
• 제15권4호
• /
• pp.177-188
• /
• 1982

The Chungju and Seosan Groups have been known usually as Precambrian formations in Korea. But their relative and absolute ages have been controvericial problem in relation with other geologic system such as so-called Ogcheon and Yeoncheon Systems in Korea. This study has mainly focused on the corelation of the Chungju Group with the Seosan Group in their stratigraphy, structure, metamorphism, and iron ore deposits. In the process of study, the auther surveyed and reclassified the Chungju and Seosan Groups and corelated with Gyeonggi and Ogch cheon metamorphic belts and got some new data. The Chungju iron-bearing formations showing transtitional relation with the Gyeonggi Gneiss Complex and the Jangamri Formation consisting mainly of pebble bearing calcarious phyllite, should be seperated from the Gyemyeongsan formation which is mainly composed of metavolcanic rocks. The Jangamri Formation and the coaly phyllite, which can be corelated respectively with the Hwaggangri Formation and Changri Formation in Ogcheon Group, are repeated in the Gyemyeonsan and Munjuri Formations with the overturned anticlinal folding(F1). So the Chungju Group which was defined as an indipendant geologic unit from the Ogcheon Group should be limited only on the Chungju iron Formation. The Seosan Group can be classified stratigraphically such as Seosan Formation consisting of iron-bearing quartzite and mica schist, Daesan Formation overlying unconformably on the Seosan Formation and Gyeonggi Gneiss Complex. Taean Formation overlying unconformably on the Daesan Formation should be seperated from Seosan Group. There are many similarity in the stratigrphy, structure, and metamorphic facies between Chungju and Seosan Groups exept the metavolcanic rocks in the Gyemyeongsan and Munjuri Formations and the pebble bearing calcareous phyllite in the Jangamri Formation. The two Groups were deformed with two kinds of differant stages, the first shows $N30^{\circ}-40^{\circ}E$ trend of fold axis, the second $N70^{\circ}-80^{\circ}W$ respectively. The Seosan Formation, which is the lowest formation in Seosan Group and bearing the iron formation, was metamorphosed at 2500 m. y. before. These age is similar with the metamorphic age of Gyeonggi metamorphic belt and with the age of Algoman and Kenoran Orogenies which devide the Precambrian into Archean and Proterozoic Era. So the Seosan Formation, which is included in some migmatitic rocks of Gyeonggi Gneiss Complex, is the oldest formation in Korea and can be corelated with the Anshan Group which bears the oldest iron formation in China. The metamorphic facies of the Precambrian metamorphism in Seosan area is simillar with that of Chungju area, showing high temperature-low pressure amphibolite facies which is corelated with the Gyeonggi metamorphic belt, the oldest metamorphic belt in Korea ($650^{\circ}-680^{\circ}C$, 3.2-4.4 Kb). The high temperature intermediate pressure amphibolite facies in Seosan area with the low temperature-intermediate presure greenschist facies of Taean formation is corelated with that of Ogcheon Group ($590^{\circ}-640^{\circ}$ C, 5.2-6.3 Kb). The Chungju and Seosan iron formations were deposited in Archean, showing geochemical composition of Precambrian iron formations. The Chungju iron formation was mainly formed by the chemical precipitation, on the other hand, the Seosan iron formation was formed by alternated action of chemical and detrital depositions.