• Korean Chemical Engineering Research
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• 제49권6호
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• pp.715-719
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• 2011

$LaCrO_{3}$를 기본으로 하는 perovskite형 재료인 $La_{0.7}Sr_{0.3}Cr_{1-x}Ni_{x}O_{3}$(0.1 ${\leq}$ x ${\leq}$ 0.5)를 citric acid와 EDTA를 이용한 졸-겔법(sol-gel method)으로 합성하였다. 제조한 촉매의 특성분석은 BET, XRD, SEM, $H_2$-TPR, EA 그리고 TEM을 이용하였고, 프로판 수증기 개질 반응을 통하여 촉매 활성을 평가하였다. Perovskite 산화물의 A-site에는 Sr을 30 ml% 고정치환하고, B-site에 Ni 치환양을 증가시키면서 프로판 수증기 개질 반응 실험을 수행한 결과 Ni 치환양과 S/C의 비(steam to carbon ratio)가 증가할수록 프로판 전환율과 수소 수율이 향상되었다. $La_{0.7}Sr_{0.3}Cr_{0.5}Ni_{0.5}O_{3}$(LSCN-0.5)촉매가 S/C의 비가 1.7이고, $800^{\circ}C$의 반응온도 조건에서 100%의 프로판 전환율과 95.9%의 높은 수소 수율을 나타내어 가장 좋은 촉매 활성을 보였다. 반응 후의 촉매에서는 filamentous cabon형태의 탄소 침적형태가 나타나며, Ni 치환양이 증가할수록 침적되는 탄소의 양이 증가하는 것을 확인하였다.

• KSBB Journal
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• 제9권4호
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• pp.365-371
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• 1994

포도당의 초기농도 10, 20, 25, 30, 40, $50g/\ell$와 $NH_4Cl$의 초기농도 0.33, 0.4, 0.5, 1.5, 3, $50g/\ell$ 의 조 합으로 형성된 발효배지를 사용하여 탄소원과 질소 원의 초기 조성비 C/N이 각종 발효 변수의 수율 및 PHB 축적량에 마치는 영향을 규명하여 보았다. 탄소원의 소비량에 대한 균체 수율 $Y_{X/X}$는 C/N비가 증가함에 따라 대단히 완만하게 감소하였으며 C/N비 70 이상에서는 일정한 값 0.35( g cell biomassl g glucose)를 나타내였다. 잔여균체 수율 $Y_{RX/S}$C/N비가 증가하면 감소하며 C/N비 65 이상에서는 일정한 값 0.065( g residual biomassl g glucose)를 나타내였다. 그러나 PHB의 수율 $Y_{PHB/S}$는 C/N비의 증가에 따라 상승하여 C/N비 40 내지 60 사이에서 최대수율 0.35( g PHB/g glucose)를 나타내었다. 균체증가량에 대한 PHB의 생성수율 $Y_{PHB/S}$는 C/N비의 증가에 따라 증가하나 C/N비 70 이상에셔는 일정한 값 0.83( g PHB/g cell mass)을 유지하였다. 또한 잔여균체량에 대한 PHB의 생성수율도 C/N비 의 증가에 따라 증가하였으며 탄소원이 더이상 소모 되지 않는 상태에셔의 건조균체량에 대한 PHB 축 적률은 C/N비에 따라 상승하여 최대값 81%에 도 달하였다. 이 경우에 대한 C/N값은 67 근방이었으 며 이 이상의 C/N비에 대한 PHB의 축적률은 81% 로 일정하였다.

• Current Photovoltaic Research
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• 제2권4호
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• pp.177-181
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• 2014

$Cu_2ZnSn(S_xSe_{1-x})_4$ (CZTSSe) absorber thin films were prepared on Mo coated soda lime glass substrates by sulfo-selenization of sputtered stacked Zn-Sn-Cu precursor thin films. The Zn-Sn-Cu precursor thin films were sulfo-selenized inside a graphite box containing S and Se powder using rapid thermal processing furnace at $540^{\circ}C$ in Ar atmosphere with pre-treatment at $300^{\circ}C$. The effect of different S/Se ratio on the structural, compositional, morphological and electrical properties of the CZTSSe thin films were studied using XRD (X-ray diffraction), XRF (X-ray fluorescence analysis), FE-SEM (field-emission scanning electron microscopy), respectively. The XRD, FE-SEM, XRF results indicated that the properties of sulfo-selenized CZTSSe thin films were strongly related to the S/Se composition ratio. In particular, the CZTS thin film solar cells with S/(S+Se)=0.25 shows best conversion efficiency of 4.6% ($V_{oc}$ : 348 mV, $J_{sc}$ : $26.71mA/cm^2$, FF : 50%, and active area : $0.31cm^2$). Further detailed analysis and discussion for effect of S/Se composition ratio on the properties CZTSSe thin films will be discussed.

• 설비공학논문집
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• 제4권2호
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• pp.123-136
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• 1992

A preliminary thermodynamic design model of two-evaporator refrigerator/freezer system is constructed. This system is based on Lorentz-Meutzner cycle using refrigerant mixtures. This model screens alternative refrigerant (R32, R125, R143a, R22, R134a, R152a, R124, R142b, R123) mixtures to select the best performance-giving refrigerant mixtures and its composition for the system. Also, it estimates the effects of cooling temperatures of intercoolers, evaporator's area ratio, cooling load ratio on the performance of the system. The COP of the system ranges from 1.4 to 1.6, which is superior to that of the single evaporator system charged with R12 by 13% to 29%. Among 15 mixtures, R22/R123, R143a/R123, R32/R142b, and R32/R124 (in the order of high COP) are most recommendable. For the case of R22/R123, R22 mass fraction more than 0.5(Load Ratio=1.0) or 0.7(Load Ratio=0.33) is recomended in order to replace R12 without reduction in volumetric capacity when keeping the compressor as the same one. COP has the highest value with X(R22)=0.7 and 0.8, respectively. For the case of R143a/R123, in the similar manner, mass fraction of R143a is more than 0.5 or 0.6 while best performance occurs at X(R143a)=0.8. Higher temperature intercooler is more important for the performance of the system than lower temperature intercooler. The area ratio of evaporators is roughly proportional to load ratio of the evaporators.

• Journal of the Korean Statistical Society
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• 제17권1호
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• pp.46-55
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• 1988

Two-piece double exponential distribution (TPDE) with one piece $(X \leq 0)$ having the scale parameter $\theta_1$ while the other piece (X>0) having $\theta_2$ is considered here. Distribution of the sum of n-independent variables from such a distribution is obtained. Special cases of this distribution are also treated. Next, distribution of the ratio of two independent (TPDE) variables is derived. As an extension, distribution of $x_1/x_2x_3$ is expressed terms of hypergeometric functions. A small table gives the power of the test regarding double exponential against (TPDE).

• 한국식품과학회지
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• 제15권1호
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• pp.56-61
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• 1983

전분질로부터 효모균체를 직접 생산하기 위하여 분리 동정된 전분이용성 효모, Sp, holsaticus FRI Y-5에 대한 배지의 탄소원과 질소원, P원, S원간의 영양균형에 대하여 실험하였다. C/P비와 C/S비가 각각 33.33과 100으로 일정할 때 비성장속도는 전분농도 67.5g/l, 그때의 C/N비가 100일 때 $0.178hr^{-1}$로 가장 빨랐으며, 최대균체량은 전분농도 90g/l C/N비가 50일 때 14g/l로 최대였다. 또한 균체수율은 전분농도 67.5g/l, C/N비가 50일 때 0.344로 가장 좋았고 균체생산속도는 전분농도 45g/l C/N비가 50일 때 0.113g/l h로 가장 빨랐다. 한편 C/P 비의 영향은, 전분농도 67.5g/l, C/N비 50, C/S비 100으로 일정할 때 균체수율과는 무관하나 비성장속도와 최대균체량은 C/P가 50일 때 각각 $0.165hi^{-1}$, 11.88g/l로 최대였다. 또한 C/S의 영향은, 전분농도 67.5g/l, C/N비 50, C/P비 33.33으로 일정할 때, 균체수율과 최대균체량은 거의 무관하나 비성장속도는 C/S비가 77.57일때 $0.157hr^{-1}$로 최대였다.

• 한국결정학회지
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• 제9권1호
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• pp.53-63
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• 1998

HWE 방법에 의해 Cd1-xZnxS 박막을 (100)방향을 Si 기판 위에 성장시켰다. 증발원과 기판의 온도를 각각 600℃, 440℃로 하여 성장시킨 Cd1-xZnxS 박막의 이중 결정 X-선 요동곡선(DCRC)의 반폭치(FWHM)값이 265 arcsec로 가장 작았다. Van der Pauw 방법으로 Hall효과를 측정하여 운반자 농도와 Hall 이동도의 온도 의존성을 조사하였다. 광전도 셀의 특성으로 spectral response, 최대 허용소비전력(MAPD), 광전류와 암전류(pc/dc)의 비 및 응답시간을 측정하였다. Cd0.53Zn0.47S광전도 셀을 Cu증기 분위기에서 열처리한 경우 감도(γ)는 0.99, pc/dc은 1.65 ×10 7 그리고 최대 허용소비전력(MAPD)은 338mW, 오름시간 (rise time)은 9.7ms, 내림시간(decay time)은 9.3ms로 가장 좋은 광전도 특성을 얻었다.

• 충청수학회지
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• 제22권2호
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• pp.155-159
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• 2009

Using the Binet's formula, we show that the quotient related ratio $l_{1(x)}\;\neq\;0$ for the eventually periodic continued fraction x. Using this ratio, we also show that the derivative of the Minkowski question mark function at the simple periodic continued fraction is infinite or 0. In particular, $l_1({[\bar{1}]})$ = 2 log $\gamma$ where $\gamma$ is the golden mean $(1+\sqrt{5})/2$ and the derivative of the Minkowski question mark function at the simple periodic continued fraction $[\bar{1}]$ is infinite.

• Asian-Australasian Journal of Animal Sciences
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• 제8권3호
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• pp.281-287
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• 1995

A study was conducted to investigate the effect of different inclusion levels of urea treated whole-crop wheat silage (UWCWS) in grass silage based rations on the performance of growing beef cattle. The winter wheat (variety, Riband) was harvested (in the summer of 1991) at a dry matter proportion of 520 g/kg and treated with feed grade urea at the rate of 37 kg/tonne crop dry matter and preserved in a heavy duty plastic bag using a silo press. The urea treated whole crop wheat silage (UWCWS) was mixed with grass silage to replace 0.00 (S100), 0.33 (S33) and 0.67 (S67) parts of the forage dry matter and fed ad libitum in a cross over design to 18 Simmental X Holstein Friesian growing beef animals. Two energy sources {one high in starch, rolled barley (RB) and one high in digestible fibre, sugar beet pulp (SBP)} were fed to supply sufficient energy for the efficient use of nitrogen by the rumen micro-organisms. The data on DMIF (dry matter intake of forage), TDMI (total dry matter intake), DLWG (daily live weight gain), FCR (feed conversion ratio) were recorded and faecal samples were collected to determine the digestibility coefficients. Results revealed that with the inclusion of UWCW in the animals' diets the DMI of the forage was significantly increased (p < 0.05). The highest DMIF was found in the treatment "S33" ($6.28{\pm}0.25kg$) where 67% of the silage dry matter was replaced with the UWCW and the lowest value for DMIF was observed in the control treatment ($5.03{\pm}0.23kg$). The DLWG did not differ significantly between the treatments. However, treatment "S100" showed a trend towards a superior DLWG. Feed conversion ratio in the control treatment differed significantly from "S67" and "S33". The addition of the UWCW in the animals' diet resulted in the lower FCR There was no effect of type of energy supplement on any aspect of performance either overall or in interaction with grass silage: UWCWS ratio. The regression and correlation coefficients for DMIF (r = 5.22 + 0.0184x*), DLWG (r = $1.04-0.00086x^{NS}$) and FCR (r = 4.78 = 0.022x*) on the inclusion of UWCW in the diet were calculated. The effect of the inclusion of UWCW on the overall digestibility coefficients was significant (p < 0.05). The addition of the UWCWS in the diet decreased the digestibility of the DM, OM, ADF and NFE but effect on the protein digestibility was non significant. The results of present study suggests that a DLWG slightly over 1 kg can be achieved with UWCW during the store period (period in which animal performance targets are low especially during winter) and the prediction of ME was overestimated as the high intake of DM did not reflect in improved animal performance.

• Clinical and Experimental Pediatrics
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• 제57권9호
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• pp.416-419
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• 2014

X-linked adrenoleukodystrophy (X-ALD) is a rare peroxisomal disorder, that is rapidly progressive, neurodegenerative, and recessive, and characteristically primary affects the central nervous system white matter and the adrenal cortex. X-ALD is diagnosed basaed on clinical, radiological, and serological parameters, including elevated plasma levels of very long chain fatty acids (VLCFA), such as C24:0 and C26:0, and high C24:0/C22:0 and C26:0/C22:0 ratios. These tests are complemented with genetic analyses. A 7.5-year-old boy was admitted to Department of Pediatrics, Chungnam National University Hospital with progressive weakness of the bilateral lower extremities. Brain magnetic resonance imaging confirmed clinically suspected ALD. A low dose adrenocorticotropic hormone stimulation test revealed parital adrenal insufficiency. His fasting plasma levels of VLCFA showed that his C24:0/C22:0 and C26:0/C22:0 ratios were significantly elevated to 1.609 (normal, 0-1.390) and 0.075 (normal, 0-0.023), respectively. Genomic DNA was extracted from peripheral whole blood samples collected from the patient and his family. All exons of ABCD1 gene were amplified by polymerase chain reaction (PCR) using specific primers. Amplified PCR products were sequenced using the same primer pairs according to the manufacturer's instructions. We identified a missense mutation (p.Arg163Leu) in the ABCD1 gene of the proband caused by the nucleotide change 488G>T in exon 1. His asymptomatic mother carried the same mutation. We have reported an unpublished mutation in the ABCD1 gene in a patient with X-ALD, who showed increased ratio of C24:0/C22:0 and C26:0/C22:0, despite a normal VLCFA concentrations.