• Korean Chemical Engineering Research
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• 제46권3호
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• pp.498-505
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• 2008

천연망간광석과 천연망간광석에 금속산화물을 $Al_2O_3$와 $TiO_2$에 담지한 촉매을 이용하여 저온 선택적 산화 반응에 대하여 연구하였다. 망간계 금속산화물은 낮은 온도에서 우수한 암모니아 전환율을 나타내었다. NMO 존재하의 저온에서의 $O_2$와 $NH_3$의 흡착 활성화에너지는 각각 10.5와 22.7 kcal/mol 임을 밝혔다. 망간광석에 미량의 Ag를 함침함으로써 활성온도를 크게 낮출 수 있었다. 티타니아 담체의 경우 저온활성이 우수하게 나타나는 특성을 보였다. 또한 구리와 망간을 사용하면 망간을 단독으로 사용한 경우보다는 저온의 활성이 우수하게 나타난다. 망간이 5 wt.% 이상에서는 동일한 전환율을 나타내고 있으며, 저온 활성이 15 wt.%까지 약간 증가함을 알 수 있으며, 20 wt.%에서는 오히려 감소하는 것으로 나타나 있다. 황산화물의 피독실험 결과 본 연구에서는 최종적으로 망간에 조촉매의 첨가에 의한 내피독성의 향상은 공정의 복잡성과 비용면에서 망간의 단독 사용보다 낮게 나타났다.

• 대한가정학회지
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• 제38권8호
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• pp.13-27
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• 2000

The background of single animal figures was originated from those northern mounted nomadic groups, which was Scythe style Culture. The art of the nomads working in the Scythian idiom was small in size and essentially decorative in intention, yet practically every object which can be associated with any unit in this group of people possesses many of the attributes essential to a real work of art. Clarity of conception, purity of form, co-ordination of rhythm and balance, and not least, an understanding and respect for the material employed were triumphantly blended by the Eurasian nomads to produce a distinctive style. In Scythian art the multitude of animal representations well illustrates the reoccupation of this nomadic people with animals in their environment. Usually only wild animals are represented. Commonly depicted are: stags and deer, lions or other large cats, eagles, birds heads (perhaps of ravens), griffins, snakes, hares, fish, goats, rams, boars, moose (elk), yak, sheep and bears. The occasional exception to the wild animal rule is domesticated horses-important because the Scythians were horse bleeders and their whole culture revolved around their dependence on the horse. The nomads had little reason to create object in honour of gods or men, but they had an instinct for beauty and the wish to surround themselves with the animal forms in which they had come to delight The Scytians tried to combine in a single rendering all the salient points of the animal they were delineating. They archived considerable success in the difficult task of showing in a single image the various and often incompatible poses assumed by a single animal in the course of its life. Zoomorphic motifs were used not simple for decorative effect, but to trim the object into amulets, with magical power to assist in hunting, and to protect the owner from harm.

• 대한토목학회논문집
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• 제10권1호
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• pp.87-97
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• 1990

사회에서 일어나는 대부분의 문제에는 안전성과 경제성 및 사용성사이에 균형을 이루어야 할 필요성이 존재한다. 이것은 특히 구조물을 설계할 때에 직접적으로 적용되는 말이며 구조물이 갖추어야 할 세가지 기본요건이 바로 이 안전성과 사용성 그리고 경제성인 것이다. 기존의 설계기준은 구조해석의 기본이론과 실제적인 경험이 복합된 설계기준으로서 하중과 강도의 불확실성을 합리적으로 고려하지 못하여 왔고, 구조의 신뢰성개념을 고려하지 못하고 있다. 따라서 본 연구에서는 좀더 합리적인 안전성과 신뢰성을 확보하기 위하여 구조신뢰이론에 토대를 둔 진보된 설계기준을 제시하고, 부분 및 조합저항계수기법을 고안하였다. 이를 위하여 우리나라의 기존 콘크리트설계규준의 신뢰수준을 평가하고 이 결과로부터 합리적(合理的)인 목표신뢰성지수를 결정하였으며, 이로부터 신뢰성이론에 근거한 새로운 설계기준을 도출하였다. 본 연구에서 유도된 부분(部分) 및 조합저항계수(組合抵抗係數)를 이용한 설계양식은 콘크리트와 철근의 구조재료특성을 효율적으로 고려하고 있어 전체저항계수를 이용한 설계양식보다 합리성을 보여주고 있으며 진보된 설계기준임을 보여주고 있다.

• 한국식품영양학회지
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• 제29권6호
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• pp.1070-1078
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• 2016

This study investigated the nutrition education realities and nutrition status of children in community child centers, by analyzing the status of nutrition education, nutrition quotient (NQ), and the level of maintaining dietary guidelines. The subjects were 173 children from grades 1 to 6, enrolled in community child centers, Jinju, Kyungnam. The NQ was examined by a questionnaire, which was a checklist of 19 food behavior items. The distribution of scores (out of 100) in the nutrition quotient were as follows: total score of NQ was 59.4, balance 56.6, diversity 60.6, moderation 65.6, regularity 60.9, and practice 56.7. Nutrition quotient was higher in the higher graders due to significant differences in the area of variety. The level of maintaining dietary guidelines was higher in girls, especially in the area 'eat politely with family', and higher amongst the upper graders in the area 'have safe snack wisely'. To improve the eating habits and nutritional status of the children in community child centers, their nutritional state should be checked with regular and systematic education, and their nutritional management should be pursued continuously. Since the assessment of the eating behaviors and the nutritional state of children is important at home as well as in schools and community child centers, nutritional education should be further extended to the parents and their care givers. This study can be implemented as basic material for the nutritional education of children, to minimize the dangers of malnutrition and to help build up the right eating habits amongst children in community child centers.

• 공업화학
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• 제31권3호
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• pp.317-322
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• 2020

수산화암모늄나이트레이트(HAN; NH₃OHNO₃)는 낮은 용융점과 증기압의 특성을 가지고 있고, 상대적으로 높은 산소균형을 이루고 있는 이온성 화합물이다. 본 연구에서는 높은 함량의 액상추진제를 제조하기 위한 산화제로 활용하기 위하여 이중용매를 적용하여 고체입자상으로 얻었다. 감압 하에서 액상의 HAN으로부터 수분을 증발시킨 후, 반용매로서 아세톤과 에탄올을 적용하여 추출한 입자상의 HAN에는 13.8 wt%의 수분이 포함되어 있었다. 아세톤을 단독으로 적용하였을 때, 합성수율은 질량기준으로 최대 88%이었고, TGA로 측정된 최대 함량은 86.2%, 분해온도는 160~205℃ 범위로 나타났다.

• 한국전산유체공학회지
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• 제20권4호
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• pp.63-69
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• 2015

The thermal balance test in vacuum chamber for satellite structures is an essential step in the process of satellite development. However, it is technically and economically difficult to fully replicate the space environment by using the vacuum chamber. To overcome these limitations, the thermal analysis through a computer simulation technique has been conducted. The CFRP composite material has attracted attention as satellite structures since it has advantages of excellent mechanical properties and light weight. However, the nonuniform nature of the thermal conductivity of the CFRP structure should be noted at the step of thermal analysis of the satellite. Two different approaches are studied for the thermal analyses; a detailed numerical modeling and a simplified model expressed by an effective thermal conductivity. In this paper, the effective thermal conductivities of the CFRP composite structures are extracted from the detailed numerical results to provide a practical thermal design data for the satellite fabricated with the CFRP composite structure. Calculation results of the surface temperature and the thermal conductivities along x, y, z directions show fairly good agreements between the detailed modeling and the simplified model for all the cases studied here.

• 한국응용과학기술학회지
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• 제32권1호
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• pp.1-6
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• 2015

본 연구에서는 발광층의 전자와 정공의 재결합 영역을 확인하고, 단계적 도핑구조를 이용하여 여기자들의 효율적인 분배를 통해 roll-off 효율을 감소시켜서 녹색 인광 유기발광다이오드의 수명 증가를 나타냈다. 발광층 내 호스트는 양극성의 4,4,N,N'-dicarbazolebiphenyl (CBP)를 사용하여 전하의 이동을 원활하게 하였다. 발광층을 네 구역으로 분할하여 각각 소자를 제작하였고, 네 구역의 도판트 농도에 따라 발광효율과 수명 향상을 보였다. 이로써 발광층 내의 단계적 도핑구조를 이용하여 캐리어와 여기자들이 원활하게 분배된 것을 확인하였다. 기준소자 대비 발광층의 도판트 농도를 5, 7, 11, 9% 순서로 단계적 도핑구조를 적용한 device C의 수명이 약 73.70% 증가하였고, 휘도 효율은 51.10 cd/A와 외부 양자 효율은 14.88%의 성능을 보였다.

• 한국응용과학기술학회지
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• 제25권4호
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• pp.459-468
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• 2008

Methyl methacrylate(MMA) was grafted onto microcrystalline cellulose(MCC) with ceric ammonium nitrate(CAN) as a redox initiator at the various conditions. The cellulose triacetate(CTA) composite films added MCC and MMA-grafted MCC powders were prepared on a glass plate. The graft yield(GY) and graft efficiency(GE) of the grafted MCC were calculated with the simple equations by the weight balance method. The double bond of C=O on the grafted MCC surfaces was confirmed by the fourier transform infrared spectroscopy with attenuated total reflection(FT-IT ATR) spectrophotometer. After grafting, the degree of crystallinity of cellulose powders was decresed by judging from x-ray diffraction(XRD) data. Scanning electron microscope(SEM) photos showed the only solvent and CAN solution could change the roughness of MCC powders and the effect of powder dispersions in composite matrix. The tensile strength of MCC/CTA composite films was decreased with increase of MCC powder contents. When 5% grafted MCC was added, the tensile strength of grafted MCC/CTA composite films was increased from 82.3 MPa to 97.2 MPa. The thermal property of powders was also analyzed by the thermogravimetric analysis(TGA).

• Journal of Microbiology and Biotechnology
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• 제9권5호
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• pp.624-630
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• 1999

In order to investigate the position of various fatty acids attached to glycerol and the specificity of Lipolase-100T, hydrolysis of fish oil was carried out with Lipolase-100T derived from Aspergillus oryzae. The amounts of free fatty acids produced from triglyceride, 1,2(2,3)-diglyceride, 1,3-diglyceride, and 2-monoglyceride and conversion rates of 1,2(2,3)-diglyceride to 1,3-diglyceride and 2-monoglyceride to 1(3)-monoglyceride were also calculated. The ratio of 1,2-diglyceride content to 1,3-diglyceride was higher than 70 in the early period of hydrolysis. The fatty acid content of the glyceride mixture after 72 h of hydrolysis was compared with that of fish oil, and it was found that polyunsaturated fatty acids such as C16:4, C20:4 n-3, C20:5 n-3, C21:5 n-3, C22:5 n-3 and C22:6 n-3 were located in the 2-position of glycerol. Material balance of each component in the hydrolysis system was written to obtain a set of simultaneous linear equations. The theoretical quantity of free fatty acids produced from triglyceride, 1,2-diglyceride, 1,3-diglyceride, and monoglyceride, respectively, were calculated by solving the linear equation system. The conversion rate of 1,2(2,3)-diglyceride to 1,3-diglyceride and that of 2-monoglyceride to 1(3)-monoglyceride were also obtained. The results showed that the migration rate of 1,2(2,3)-diglyceride to 1,3-diglyceride was higher than the hydrolysis rate of 1,2(2,3)-diglyceride to 2-monoglyceride and the conversion rate of 2-monoglyceride to 1(3)-monoglyceride was extremely low.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2010년도 제39회 하계학술대회 초록집
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• pp.74-74
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• 2010

The aqua-plasma is the non-thermal plasma in electrical conductive electrolyte by generates the vapor film layer on the immersed metal electrode surface. This plasma can generate the hydroxyl radical by dissociate the water molecule with the plasma electron. To develop the plasma discharge device for high efficiency in the hydroxyl radical generation, proper model for estimation of plasma power is necessary. In this work, the 1-D spherical model was developed, considering temperature dependence material constants. The relation between the plasma power and hydroxyl generation was also studied by the comparison between the optical emission intensity from the hydroxyl radical using monochromator and estimated plasma power. First, the thickness of vapor layer thickness was estimated using the Navier-Stokes fluid equation in order to calculate the discharge E-field inside vapor layer. Using the E-field magnitude and power balance on the plasma generation, it was possible to estimate the plasma power. The plasma power was assumed to uniformly fill the vapor layer and the temperature of vapor layer was fixed in the boiling temperature of electrolyte, 375K. In the experiment, the aqua-plasma was discharged in the saline by applied the voltage on the bipolar electrode. The range of applied voltage was 234 to 280V-rms in the frequency of 380 kHz. Two type electrodes were produced with two ${\Phi}0.2$ tungsten. The plasma power was estimated from the V-I signal from the two high voltage probes and current probe. The estimated plasma power agreed with the profile of emission intensity when the plasma discharged between the metal electrode and vapor layer surface. However, when the plasma discharged between the metal electrodes, the increasing rate of emission intensity was lower than the increase of plasma power. It implies that the surface reaction is more sufficient rather than the volume reaction in the radical generation, due to the high density of water molecule in the liquid.