• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 1999년도 유체기계 연구개발 발표회 논문집
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• pp.309-314
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• 1999

This paper is concerned with the viscous interaction between rotor and stator The viscous interaction is caused by wakes from upstream blades. The cascade was composed with five blades and cylinders were placed to make wakes and their location was about 50 percent of blade chord upstream. The location of cylinders were varied in the cascade axis with 0, 20, 40, 60 and 80 percent of pitch length. The velocity distribution in the cascade passage were measured using single slanted hot-wire and the ones in the boundary layer using boundary probe. As a result, wakes decay more rapidly at suction surface and more slowly at pressure surface. And the measurement of momentum thickness of cascade shows that the momentum thickness is larger near the blade surface. From measurement of blade boundary layer, turbulent intensity is also larger near the blade surface because wakes collide the boundary layer And wakes make boundary layer thickness smaller and delay flow separation.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.535-536
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• 2005

Organic photovoltaic effects were studied in a device structure of ITO/CuPc/Al and ITO/CuPc/$C_{60}$/BCP/Al. A thickness of CuPc layer was varied from 10 nm to 50 nm, we have obtained that the optimum CuPc layer thickness is around 40 nm from the analysis of the current density-voltage characteristics in CuPc single layer photovoltaic cell. From the thickness-dependent photovoltaic effects in CuPc/$C_{60}$ heterojunction devices, higher power conversion efficiency was obtained in ITO/20nm CuPc/40nm $C_{60}$/Al, which has a thickness ratio (CuPc:$C_{60}$) of 1:2 rather than 1:1 or 1:3. Light intensity on the device was measured by calibrated Si-photodiode and radiometer/photometer of International Light Inc(IL14004).

• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2006년도 추계학술대회 논문집
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• pp.135-140
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• 2006

The stabilization mechanism of turbulent, lifted jet flames in a non-premixed condition has been studied experimentally. The objectives are to explain the phenomenon of a liftoff height decreasing as increasing fuel velocity and to reveal the mechanisms of flame stability Hydrogen was varied from 100 to 300 m/s and a coaxial air was fixed at 16 m/s with a coflow air less than 0.1 m/s. The technique of PIV and OH PLIF was used simultaneously with CCD and ICCD cameras. It was found that the liftoff height of the jet decreased with an increased fuel jet exit velocity. The leading edge at the flame base was moving along the stoichiometric line. Finally we confirmed that the stabilization of lifted hydrogen diffusion flames is related with a turbulent intensity, which means combustion is occurred where the local flow velocity is equal to the turbulent flame propagation velocity.

• 대한기계학회논문집B
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• 제26권2호
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• pp.219-226
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• 2002

This paper is concerned with the effects of periodically approaching upstream wakes on cascade-flow and loss. The reduced frequency of the periodic wakes was varied in the narrow range from 0.5 to 0.7 Corresponding to a wake-passing through the cascade, two velocity deficits appeared near the boundary layer contour in the downstream from about 60% chord-length. The first velocity deficit was caused by a periodic wake and the second one appeared after some delayed time. The second velocity deficit was interpreted as the results of reattachment of flow-separation. The higher reduced frequency decreased the duration time of separation appearance and the lesser losses of blade were resulted.

• 한국자기학회지
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• 제5권5호
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• pp.461-464
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• 1995

We have investigated the effects of sputtering Ar gas pressure on magnetic anisotropy of Co/Pt multilayers, where sputtering Ar gas pressure was varied from 2 to 20 mTorr. The surface and volume anisotropies were found to be strongly dependent on sputtering Ar gas pressure. In particular, the surface anisotropy exhibited more than fourfold enhancement as Ar pressure was decreased from 20 to 5 mTorr. We have found that the surface anisotropy was closely correlated with the low-angle x-ray diffraction intensity. We believe that these results are mainly ascribed to the variation of microstructure in the Co/Pt multilayer thin films with sputtering Ar gas pressure.

• 한국산림과학회지
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• 제73권1호
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• pp.43-54
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• 1986

파종상(播種床)에서 피음처리(被陰處理)를 행(行)한 잣나무 유묘(幼苗)의 상대광도별(相對光度別) 생장관계(生長關係)를 분석(分析)하였던 바 기(其) 결과(結果)를 요약(要約)하면 다음과 같다; 1) 신장생장(伸長生長)에 있어서 지상부(地上部)는 상대광도(相對光度) 37% 구(區)에서, 그리고 기외(其外)의 기관(器官)은 100% 구(區)에서 가장 크게 나타났다. 광도(光度)가 지상부(地上部) 및 지하부(地下部), 묘장(苗長), 직경생장(直徑生長)에 미치는 영향(影響)은 기여율(寄與率) 93%, 26.2%, 21.4%. 48.7%였다. 2) 엽령(葉令)에 따라 엽속(葉束) 및 엽장(葉長)의 변화(變化)는 크게 나타났다. 엽속(葉束)은 1년생(年生)의 경우 광도(光度)가 높을수록, 그리고 2년생(年生)은 상대광도(相對光度) 37% 구(區)에서 가장 많았다. 그리고 엽장(葉長)은 각(各) 처리간(處理間)에 큰 차(差)가 없었다. 이때 광도(光度)가 미치는 엽속(葉束) 및 엽령(葉令)에 대(對)한 기여율(寄與率)은 각각(各各) 39%, 27.8% 였고 엽장(葉長)은 2.5%였다. 3) 중량생장(重量生長)은 상대광도(相對光度) 100% 구(區)에서 가장 컸으나 점차 광도(光度)가 낮아짐에 따라 감소(減少)하는 경향(傾向)이었다. 광도(光度)가 미치는 기여율(寄與率)은 생중량(生重量) 및 건중량(乾重量)의 경우 38%와 7.6%였고, 엽건중량(葉乾重量)은 13.18%로 나타났다. 4) T/R 율(率)은 상대광도(相對光度)가 점차 낮아 질수록 증가(增加)하는 경향(傾向)이었다. 이때 광도(光度)가 T/R율(率)에 미치는 기여율(寄與率)은 7.0%였다. 5) 엽건중량(葉乾重量)과 타기관(他器官)의 생장량간(生長量間)에는 정(正)의 상관(相關)을 인정(認定)할 수 있었고 이들간에는 직선회귀(直線回歸) 관계(關係)에 있음도 알 수 있었다.

• 대한화장품학회지
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• 제26권1호
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• pp.261-274
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• 2000

당류계 계면활성제인 sucrose distearate(S110), sucrose monostearate(S160), POE(20) ethyl glucose stearate(SSE20)과 오일성분인 알칸 계열의 탄화수소 hexane( $C_{6}$), decane( $C_{10}$), tetradecane( $C_{l4}$), octadecane( $C_{8}$)과 squalane (SQ) , liquid paraffin(LP) , octylpalminate(OP) , octylstearate(OS), alkylbenzoate(AB), isostearylbenzoate(ISB)를 사용하여 에멀젼을 제조하였으며 에멀젼 입자의 구조 형태는 광산란법을 이용하여 fractal 차원으로 나타내었다. 에멀젼 입자의 fractal 차원은 오일의 농도 및 탄소수와 오일의 비극성이 증가함에 따라 크게 나타났다. fractal 차원은 대부분 1.7~2.8으로 입자의 구조 형태는 fractal 구조를 이루고 있으나, S110계와 S160계의 Cla 50, LP의 fractal 차원은 3.0~3.2으로 내부 구조가 비교적 조밀한 회합체 구조를 형성하였다. S160계와 S110계의 fractal 차원은 2.I~2.6으로 서로 비슷한 fractal 구조를 형성하며, SSE20의 fractal 차원는 1.5~2.1으로 S160계 및 S110계 보다 덜 조밀한 회합체 구조를 이루는 것으로 나타났다. 입자의 구조 형태는 오일과 계면활성제의 종류에 영향을 받으며 계면활성제의 친수부가 동일하면 비슷한 구조를 형성하였으며 S160의 친수부 구조인 sucrose보다 SSE20의 polyoxyethylene group에 의한 장애효과가 더욱 크게 나타났다.다..

• 한국세라믹학회지
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• 제31권12호
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• pp.1577-1587
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• 1994

TiO2 thin films with the substitution of oxygen with nitrogen were deposited on silicon substrate by metalorganic chemical vapor deposition (MOCVD) using Ti(OCH(CH3)2)4 (titanium tetraisopropoxide, TTIP) and N2O as source materials. X-ray diffraction (XRD) results indicated that the crystal structure of the deposited thin films was anatase TiO2 with only (101) plane observed at the deposition temperatures of 36$0^{\circ}C$ and 38$0^{\circ}C$, and with (101) and (200) plane at above 40$0^{\circ}C$. Raman spectroscopic results indicated that the crystal structure was anatase TiO2 in accordance with the XRD results without any rutile, fcc TiN, or hcp TiN structure. No fundamental difference was observed with temperature increase, but the peak intensity at 194.5 cm-1 increased with strong intensity at 143.0 cm-1 for all samples. The crystalline size of the films varied from 49.2 nm to 63.9 nm with increasing temperature as determined by slow-scan XRD experiments. The refractive index of the films increased from 2.40 to 2.55 as temperature increased. X-ray photoelectron spectroscopy (XPS) study showed only Ti 2s, Ti 2p, C 1s, O 1s and O 2s peaks at the surface of the film. The composition of the surface was estimated to be TiO1.98 from the quatitative analysis. In the bulk of the film Ti 2s, Ti 2p, O 1s, O 2s, N 1s and N 2s were detected, and Ti-N bonding was observed due to the substitution of oxygen with nitrogen. A satellite structure was observed in the Ti 2p due to the Ti-N bonding, and the composition of titanium nitride was determined to be about TiN1.0 from the position of the binding energy of Ti-N 2p3/2 and the quatitative analysis. The spectrum of Ti 2p energy level could be the sum of a 4, 5, or 6 Gaussian curve reconstruction, and the case of the sum of the 6 Gaussian curve reconstruction was physically most meaningful. From the results of Auger electron spectroscopy (AES), it was known that the composition was not varied significantly throughout the whole thickness of the film, and silicon oxide was not observed at the interface between the film and the substrate. The composition of the film was possible (TiO2)1-x.(TiN)x or TiO2-2xNx and in this experimental condition x was found to be about 0.21-0.16.

• 한국진공학회지
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• 제15권4호
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• pp.404-409
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• 2006

RF magnetron sputtering 법을 이용하여 quartz 기판 위에 spinel 구조의 $ZnGa_2O_4 : Mn^{2+}$ 박막 형광체를 상온에서 증착 하였다. 후 열처리 온도에 따라 박막의 결정성, 표면 거칠기와 조성비가 변하였으며 이는 박막 형광체의 발광특성에 영향을 주었다. 후 열처리 온도가 $500^{\circ}C$에서 $900^{\circ}C$로 올라감에 따라 후 열처리 온도가 $700^{\circ}C$ 일 때 가장 낮은 수치의 표면 거칠기를 보였고 이로 인한 낮은 외부 양자 효율로 인하여 발광특성이 좋지 않았다. 후 열처리 온도가 $800^{\circ}C$ 일 때 결정화 정도가 좋았으며 적당한 표면 거칠기와 화학적 조성비로 인해 최적의 발광특성을 보였다. 반면 후 열처리 온도가 $900^{\circ}C$ 일 때 결정성은 가장 좋았으나 Zn의 높은 증기압으로 인한 화학적 조성비의 깨짐으로 발광특성이 좋지 못하였다.

• Journal of Biosystems Engineering
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• 제43권3호
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• pp.237-246
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• 2018

Purpose: This study (a) investigated the effect of microwave power intensity and sample thickness on microwave drying characteristics of radish strips, and (b) determined the best-fit drying model for describing experimental drying data, effective moisture diffusivity ($D_{eff}$), and activation energy ($E_a$) for all drying conditions. Methods: A domestic microwave oven was modified for microwave drying and equipped with a small fan installed on the left upper side for removing water vapor during the drying process. Radishes were cut into two fixed-size strip shapes (6 and 9 mm in thickness). For drying experiments, the applied microwave power intensities ranged from 180 to 630 W at intervals of 90 W. Six drying models were evaluated to delineate the experimental drying curves of both radish strip samples. The effective moisture diffusivity ($D_{eff}$) was determined from Fick's diffusion method, and the Arrhenius equation was applied to calculate the activation energy ($E_a$). Results: The drying time was profoundly decreased as the microwave power intensity was increased regardless of the thickness of the radish strips; however, the drying rate of thicker strips was faster than that of the thinner strips up to a certain moisture content of the strip samples. The majority of the applied drying models were suitable to describe the drying characteristics of the radish strips for all drying conditions. Among the drying models, based on the model indices, the best model was the Page model. The range of estimated $D_{eff}$ for both strip samples was from $2.907{\times}10^{-9}$ to $1.215{\times}10^{-8}m^2/s$. $E_a$ for the 6- and 9-mm strips was 3.537 and 3.179 W/g, respectively. Conclusions: The microwave drying characteristics varied depending on the microwave power intensity and the thickness of the strips. In order to produce high-quality dried radish strips, the microwave power intensity should be lower than 180 W.