• 한국세라믹학회지
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• 제37권3호
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• pp.247-255
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• 2000

Silicon carbide with sialon was prepared by hot pressing and transient liquid-phase sintering, and the effects of sintering atmosphere and starting phases on their microstructural characteristics were investigated. The sintered SiC with Sialon composition(Y2O3, AlN, Si3N4) in argon atmosphere had high sintered density and large aspect ratio. But sintered specimens in nitrogen atmosphere showed low aspect ratio and small grian size, becuase of the retardation of phase transformation and grain growth. Addition of Y-Sialon powder to SiC also retarded the phase transformation to ${\alpha}$-SiC from ${\beta}$-SiC and densification. The SiC specimen prepared from the starting ${\beta}$-SiC powder with Sialon composition(Y2O3, AlN, Si3N4) showed the highest fracture toughness about 6.0 MPa$.$m1/2.

• 한국재료학회지
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• 제29권10호
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• pp.579-585
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• 2019

In this study, we investigate the effect of Al/N source ratios and growth rates on the growth and structural properties of AlN films on c-plane sapphires by plasma-assisted molecular beam epitaxy. Both growth rates and Al/N ratios affect crystal qualities of AlN films. The full width at half maximum (FWHM) values of ($10{\bar{1}}5$) X-ray rocking curves (XRCs) change from 0.22 to $0.31^{\circ}$ with changing of the Al/N ratios, but the curves of (0002) XRCs change from 0.04 to $0.45^{\circ}$ with changing of the Al/N ratios. This means that structural deformation due to dislocations is slightly affected by the Al/N ratio in the ($10{\bar{1}}5$) XRCs but affected strongly for the (0002) XRCs. From the viewpoint of growth rate, the AlN films with high growth rate (HGR) show better crystal quality than the low growth rate (LGR) films overall, as shown by the FWHM values of the (0002) and ($10{\bar{1}}5$) XRCs. Based on cross-sectional transmission electron microscope observation, the HGR sample with an Al/N ratio of 3.1 shows more edge dislocations than there are screw and mixed dislocations in the LGR sample with Al/N ratio of 3.5.

• 공업화학
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• 제16권3호
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• pp.397-402
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• 2005

Core-shell 형의 Poly(styrene-co-N-isopropylacrylamide) (poly(St-co-NIPAm)) 마이크로겔은 과항상칼륨(KPS)을 개시제로 사용하여 styrene (St)과 N-isopropylacrylamide (NIPAm)의 무유화 유화중합으로 제조하였다. St/NIPAm의 비, 모노머의 농도, 가교제의 농도에 따른 입자크기의 영향을 조사하였으며 고분자 마이크로겔의 온도에 따른 열감응성을 조사하였다. 마이크로겔의 입자 크기는 NIPAm의 몰비에 따라 증가하였으며 마이크로겔 분산용액의 투과도가 하한임계온도 이상($32{\sim}34^{\circ}C$)에서는 급격히 감소였다. 수용액 중에서 마이크로겔의 팽윤성은 모노머인 NIPAm의 농도가 증가할수록 증가하였으며 가교제의 농도에 따라서 감소하였다.

• 한국식품영양과학회지
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• 제19권6호
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• pp.641-645
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• 1990

In order to study the influence of culture conditions on cell growth and lipid formation by Mucor sp, various carbon and nitrogen sources initial pH and C./N ratio of medium were investigated. Glucose was found to be suitable carbon source in terms of lipid yield and ${\gamma}$-linolenic acid(GLA) content. When NH4Cl and (NH4)2SO4 were used as nitrogen source lipid content was high(19-21%) but GLA content was low(15-17%) On the other hand when NaNO3 and KNO3 were used lipid content was low(about 13%) but GLA content was high(22-23%). The highest production of lipid was obtained at a C/N ratio of 40 using glucose and (NH4)2SO4 as carbon and nitrogen source respectively. it was found that lipid yield was high at pH4.6 Also this fungus did not grow at 35$^{\circ}C$ and lipid yield was highr at 15$^{\circ}C$ than $25^{\circ}C$.

• 한국세라믹학회지
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• 제38권12호
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• pp.1150-1154
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• 2001

플라즈마 화학기상증착(PECVD)법을 이용하여 실리카 광도파막의 코어로 이용되는 규소질산화막(SiON)을 Si 웨이퍼 위에 SiH$_4$,$N_2$O, $N_2$가스를 혼합하여 저온(32$0^{\circ}C$)에서 증착하였다. Prism coupler 측정을 통해 SiON 굴절률 1.4663~1.5496을 얻었으며, SiH$_4$/($N_2$O+$N_2$) 유량비와 rf power가 각각 0.33과 150W에서 8.67$mu extrm{m}$/h의 증착률을 나타내었다. 또한 SiH$_4$/($N_2$O+$N_2$) 유량비가 감소함에 따라 SiON막의 roughness는 41~6$\AA$까지 감소하였다.

• 유기물자원화
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• 제2권1호
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• pp.75-86
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• 1994

우리나라에서 발생되는 음식쓰레기는 퇴비화 처리시 높은 수분함량과 낮은 C/N비를 적정 수준으로 조절하기 위해 bulking agent를 첨가함이 필수적이며 그의 정확한 첨가량을 계산하는 것은 퇴비화에 소요되는 비용을 결정하는데 중요한 요소로 적용하게 된다(Hay et al., 1998). 그러나 bulking agent의 첨가량을 계산하기 위한 기준지표 중의 하나인 C/N비의 경우 혼합되는 bulking agent의 분해정도가 고려되지 않은 총 탄소와 질소의 비에 기준하여 적정 첨가비율이 정해지고 있기 때문에 실제 요구되는 탄소와 질소의 양을 초과 또는 미달하는 경우가 발생될 수 있으며, 이는 곧 bulking agent의 과다첨가 또는 반응속도 저하로 인한 처리비용의 상승과 직결될 수 있다. 본 연구에서는 음식쓰레기의 퇴비화를 위한 bulking agent의 정확한 첨가량을 정량적으로 제시하기 위하여 bulking agent의 첨가로 인한 반응향상 여부와 그 원인을 분석하여 이를 바탕으로 적정 첨가량 결정법을 제안하였다. 그 결과 실질적으로 분해가능한 탄소원을 포함하고 있는 쌀밥의 첨가는 C/N비가 낮은 음식쓰레기의 퇴비화반응을 향상시킬 수 있으나, 분해가 쉽지 않은 톱밥을 bulking agent로 첨가할 경우는 음식쓰레기의 탄소원을 제공함으로써 반응을 향상시킨다기 보다는 음식쓰레기의 통기성을 개선하여 줌으로써 활발한 퇴비화 반응을 유도한다는 사실을 확인할 수 있었다. 따라서, bulking agent는 그 첨가량을 많이 할수록 퇴비화반응에 유리하며, 일반적인 적정 C/N비값 이상의 첨가율에서도 반응 향상이 가능한 것으로 예상된다. 또한 bulking agent 첨가량의 증가로 인한 통기성의 향상효과는 해당 조건하에서의 적정 수분함량값 증가요소로 작용하는 것으로 나타나 이를 종합적으로 고려한 bulking agent첨가량 결정이 필요함을 알 수 있었다. 이상과 같은 실험적 분석의 결과를 종합할 때, 음식쓰레기 100g당 78g의 톱밥을 첨가하여 C/N비를 25 수분함량을 56%로 각각 조절하는 것이 본 연구에서 다루어진 음식쓰레기의 활발한 퇴비화를 위해서는 적절하며, 이러한 첨가량의 계산법은 실제 퇴비화시설의 적정 운전을 위해서 적용함이 바람직한 것으로 판단되었다.

• Journal of Microbiology and Biotechnology
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• 제12권6호
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• pp.979-985
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• 2002

The possibility of microalgal nitrogen treatment was tested in wastewaters with a low carbon/nitrogen (C/N) ratio. Chlorella kessleri was cultured in the two different artificial wastewaters with nitrate as a nitrogen source: one contained glucose for an organic carbon source and the other without organic carbon sources. The growth rates of the two cultures were almost identical when the aeration rate was over 1 vvm. These results suggest that microalgae could successfully remove nitrogen from wastewater, as far as the mass transfer of $CO_2$, was not limited. Nitrate was successfully reduced to below 2 mg $NO_3^-$-N/ml from the initial nitrate concentration of 140 mg $NO_3^-$-N/ml in 10 days, even in the wastewater with no organic carbon source. Similar results were obtained when ammonium was used as the sole nitrogen source instead of nitrate. Higher concentrations of nitrogen of 140, 280, 560 and 1,400 mg/ml were also tested and similar amounts of nitrogen were removed by algal cultures without showing any substrate inhibition.

• Journal of Information Display
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• 제11권3호
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• pp.109-112
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• 2010

The solid phase compositions and dielectric properties of silicon nitride ($SiN_x$) films prepared using the plasma enhanced chemical vapor deposition (PECVD) technique at a low temperature ($200^{\circ}C$) were studied. Controlling the source gas mixing ratio, R = $[N_2]/[SiH_4]$, and the plasma power successfully produced both silicon-rich and nitrogen-rich compositions in the final films. The composition parameter, X, varied from 0.83 to 1.62. Depending on the film composition, the dielectric properties of the $SiN_x$ films also varied substantially. Silicon-rich silicon nitride (SRSN) films were obtained at a low plasma power and a low R. The photoluminescence (PL) spectra of these films revealed the existence of nano-sized silicon particles even in the absence of a post-annealing process. Nitrogen-rich silicon nitride (NRSN) films were obtained at a high plasma power and a high R. These films showed a fairly high dielectric constant ($\kappa$ = 7.1) and a suppressed hysteresis window in their capacitance-voltage (C-V) characteristics.

• 대한지역사회영양학회지
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• 제14권6호
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• pp.789-797
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• 2009

In order to investigate the effects of frequent eating-out and breakfast skipping of working men on body mass index and nutrients intake status, working male adults aged 20 or over were selected (n = 1883) from the data of 2001 Korea national health and nutrition survey. The subjects were divided into 4 groups according to the eating-out frequency(high: once or more daily, low: less than once daily) and breakfast eating or not. Four groups were high eating-out with breakfast eating (n = 609), high eating-out with breakfast skipping (n = 192), low eating-out with breakfast eating (n = 877), and low eating-out with breakfast skipping (n = 205). High eating-out group showed higher body mass index (BMI) than low eating-out group, but the difference of BMI was disappeared when adjusted with age, residence region and family income. However high eating-out group in case of breakfast eating, compared with the low eating-out, showed higher intakes or densities of energy, fat, fat-energy% and higher ratio of energy-fat overintake, and also showed higher mean nutritional adequacy ratio and lower ratio of nutrients intake deficiency. Calcium, iron, vitamin A and C intakes were not affected by eating-out frequency, but were lowered by breakfast skipping. Breakfast skipping also decreased intake frequency of unprocessed cereals and increased those of ramyon and carbonated and alcoholic beverages. From the results frequent eating-out with breakfast eating caused increased intakes of energy and fat, but did not cause BMI increase. Breakfast skipping, but not eating-out, had negative influences on mineral and vitamin intakes. Accordingly good eating-out as well as breakfast eating should be exceedingly emphasized at nutrition education for the working males.

• Animal Bioscience
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• 제35권5호
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• pp.730-739
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• 2022

Objective: This study investigated the effects of dietary n-6:n-3 polyunsaturated fatty acid (PUFA) ratio on growth performance, blood indexes, tissue fatty acid composition and the gene expression in finishing pigs. Methods: Seventy-two crossbred ([Duroc×Landrace]×Yorkshire) barrows (68.5±1.8 kg) were fed one of four isoenergetic and isonitrogenous diets with n-6:n-3 PUFA ratios of 2:1, 3:1, 5:1, and 8:1. Results: Average daily gain, average daily feed intake and gain-to-feed ratio had quadratic responses but the measurements were increased and then decreased (quadratic, p<0.05). The concentrations of serum triglyceride, total cholesterol and interleukin 6 were linearly increased (p<0.05) with increasing of dietary n-6:n-3 PUFA ratio, while that of high-density lipoprotein cholesterol tended to decrease (p = 0.062), and high-density lipoprotein cholesterol:low-density lipoprotein cholesterol ratio and leptin concentration were linearly decreased (p<0.05). The concentration of serum adiponectin had a quadratic response but the measurement was decreased and then increased (quadratic, p<0.05). The proportion of C18:3n-3 was linearly decreased (p<0.05) in the longissimus thoracis (LT) and subcutaneous adipose tissue (SCAT) as dietary n-6:n-3 PUFA ratio increasing, while the proportion of C18:2n-6 and n-6:n-3 PUFA ratio were linearly increased (p<0.05). In addition, the expression levels of peroxisome proliferator-activated receptor gamma (PPARγ) and lipoprotein lipase in the LT and SCAT, and adipocyte fatty acid binding protein and hormone-sensitive lipase (HSL) in the SCAT had quadratic responses but the measurements were increased and then decreased (quadratic, p<0.05). The expression of HSL in the LT was linearly decreased (p<0.05) with increasing of dietary n-6:n-3 PUFA ratio. Conclusion: Dietary n-6:n-3 PUFA ratio could regulate lipid and fatty acid metabolism in blood and tissue. Reducing dietary n-6:n-3 PUFA ratio (3:1) could appropriately suppress expression of related genes in PPARγ signaling, and result in improved growth performance and n-3 PUFA deposition in muscle and adipose tissue in finishing pigs.