• Korean Journal of Food Science and Technology
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• v.29 no.1
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• pp.126-132
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• 1997

Calcium carbonate ($CaCO_3$) immobilized with alginate was studied as buffer system to enhance the cultivation efficiency of Bifidobacterium longum (ATCC 15707) which is inhibited at low pH. To test the bufferring effect of the immobilized $CaCO_3$ beads, pH value in each modified trypticase-proteose peptone-yeast (TPY) broth which is adjusted to pH 4.0 with acetic acid, lactic acid and complex solution of acetic and lactic acid, 3:2 (M:M) was tested by concentration of $CaCO_3$ bead and reaction time. The bufferring effect of $CaCO_3$ bead became higher with increasing the amount of $CaCO_3$ bead in the acidic solution. The growth rate of bifidobacteria and bufferring effect were examined in relation to the amount of $CaCO_3$ bead and concentration of glucose in the modified TPY media. The growth rate of bifidobacteria and bufferring effect were increased with increasing the amount of $CaCO_3$ bead and concentration of glucose. Also, the exponential time of bifidobacteria became longer with increasing the amount of $CaCO_3$ bead and concentration of glucose in the modified TPY media. When we observed the growth rate of bifidobacteria by the method of pH-controlled culture and $CaCO_3$ buffer system, the $CaCO_3$ buffer system was more effective than that of pH-controlled culture. Therefore, this $CaCO_3$ buffer system may be useful as a method to enhance of the cultivation efficiency of bifidobacteria.

• Journal of the Korean Magnetics Society
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• v.8 no.1
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• pp.1-5
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• 1998

Acicular Fe-Co alloy particles are one of the candidates for high-density magnetic recording media. We examined the effects of Co additions on the magnetic properties of Fe-Co alloy particles by using M$\'{o}$ssbauer spectroscopy, TEM, and X-ray diffraction. Acicular $Fe_n$Co (n=5, 4, 3, 2) alloy particles coated with silica, were prepared by a chemical coprecipitation method and subsequent H $_2$ reduction. The crystal structure was found to be cubic in all n ranges. The lattice constant $a_0$ decreases with increasing Co contents. Analysis of $^{57}Fe$ M\'{o}$ssbauer effect data in terms of the local configurations of Co atoms has permitted the influence of magnetic hyperfine interactions to be monitored.

• Korean Chemical Engineering Research
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• v.48 no.2
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• pp.253-258
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• 2010

In the field of the $CO_2$ absorption process using aqueous ammonia, the effects of regeneration pressure and temperature on $CO_2$ absorption performances of the aqueous ammonia were investigated. The absorbents were prepared by dissolving ammonium carbonate solid in water to grant the resulted solution 0.5 $CO_2$ loading ($mol\;CO_2/mol\;NH_3$) and various ammonia concentration (14, 20, 26 and 32 wt%). As-prepared absorbents were regenerated at high pressure and temperature (over $120^{\circ}C$ and 6 bar) before the absorption test. The absorption test was carried out by injecting the simulated gas that contains 12 vol% of $CO_2$ into a bubbling reactor. The introduction of 26 wt% of the ammonia concentration for $CO_2$ absorption test resulted in the higher absorption capacities than other experimental conditions. In particular, when the absorbents with 26 wt% of the ammonia were regenerated at $150^{\circ}C$ and 14 bar, the highest absorption capacity, $45ml\;CO_2/g$, was obtained. According to the analysis of absorbents using acid-base titration, the ammonia loss during the regeneration of the absorbents with a fixed ammonia concentration decreased as the regeneration pressure increased, while it increased as the regeneration temperature increased. In the condition of fixed regeneration pressure and temperature, as expected, the ammonia loss increased as the ammonia concentration increased. The measured $CO_2$ loadings and ammonia concentrations of absorbents were compared to the values calculated by Electrolyte NRTL model in Aspen Plus.

• Journal of the Korean Society of Food Science and Nutrition
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• v.35 no.10
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• pp.1439-1443
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• 2006

This study was performed on the effects of extraction temperature, pressure, time on apparent solubility and extraction yield of perilla oil and tocopherol, and color and fatty acid composition of the residue in supercritical carbon dioxide $(SC-CO_2)$ extraction. Apparent solubility of perilla oil and tocopherol increased with the increase of $CO_2$ density and was found to strongly depend on extraction pressure rather than extraction temperature. The extract yield of tocopherol in $SC-CO_2$ extraction increased with an increase of temperature and decreased with an increase of pressure and extraction time. The perilla oil apparent solubility of dried perilla powder for $60\sim180$ min at $40^{\circ}C/276$ bar increased with an extraction time, on the other hands, tocopherol apparent solubility decreased. As the increase of $CO_2$ density, less redness and yellowness increased. Fatty acid composition of perilla oil showed that perilla oil extracted by $SC-CO_2$ had better unsaturated fatty acid and decreased in saturated fatty acid. $SC-CO_2$ extraction offers a safe natural method for gaining perilla oil from dried perilla seeds powder.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.3
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• pp.602-606
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• 2009

The absorption capacity and initial absorption rate in 5 %, 10%, 15 % and 20% $Na_{2}CO_{3}$ under the constant temperature at $40^{\circ}C$ and the initial absorption rate in mixture of different alkaline salts such as $KHCO_3$, $CaCO_3$ and $K_{2}CO_{3}$ were measured using batch type stirred cell contractor. 10% $Na_{2}CO_{3}$ showed the highest absorption capacity and $Na_{2}CO_{3}$ and $K_{2}CO_{3}$ showed the somewhat increased absorption capacity and initial absorption rate respectively. Further more, we have studied the effect of adding Pz and Pp to $Na_{2}CO_{3}$. The result showed that absorption rate of $CO_2$ was increased by adding these additives.

• Journal of Korean Ophthalmic Optics Society
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• v.3 no.1
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• pp.229-235
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• 1998

This paper reports the preparation and characterization of colored coatings of $SiO_2-TiO_2-M_xO_y$ (M = Co, Cr or Cu). Films of different compositions ranging from a molar content of transition metals of 5% to 20% have been prepared on soda-lime-silica slide glasses by the sol-gel process. The films have been characterized by a photospectroscopy. The color and reflectance of the films was expressed in Lab color chart and on spectra plot. 'L' as lightness and all reflectance decreased with increase of the content of transition metals. The coating of Co, Cu and Cr cotaining system showed light blue, green and lemon-yellowish color, respectively.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2011.06a
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• pp.277-277
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• 2011

본 논문은 $CO_2$ 히트펌프용 모세관의 기초 설계자료를 제공하기 위해서 모세관 길이 예측에 대해서 이론 및 실험적으로 조사하였다. 본 연구에서 고려된 작동변수로는 증발온도, 가스냉각기 냉각압력, 냉매유량, 모세관의 관경 등이다. 몇몇연구자들의 자료를 바탕으로 $CO_2$ 모세관 길이를 예측할 수 있는 수학적 모델식을 작성하였다. 그리고 단열 모세관 팽창장치내 $CO_2$의 증발온도, 냉매유량, 냉각압력 등에 대해서 실험한 결과, Fig. 1에 나타낸 것처럼, 모세관 길이가 증가할수록 증발온도는 감소하는 것을 알 수 있다. 그리고 증발온도에 대한 실험값과 예측값의 비교 결과, 실험값이 예측값보다 약간 높게 나타났다. $CO_2$냉매가 모세관내를 통과할 때 플래쉬 가스(flash gas)의 발생으로 인해 액상의 양보다 기상의 양이 많아지고 액상의 압력강하보다 기상의 압력강하가 휠씬 더 크기 때문이다. 또한 증발온도에 대한 실험값과 예측값은 6.5~9.9% 이내에서 좋은 일치를 보였다. Fig. 2에 나타낸 것처럼, 모세관 길이가 증가할수록 냉매유량은 감소하는 것을 알 수 있다. 이는 전술한 바와 같이 모세관 길이가 증가할수록 냉매 압력강하가 더욱더 증가하기 때문이다. 그리고 냉매유량에 대한 실험값과 예측값의 비교 결과, 실험값이 예측값보다 약간 높게 나타났다. 이는 전술한 증발온도와 동일한 이유로 실제 $CO_2$냉매가 모세관내를 통과할 때 플래쉬 가스의 발생량이 많아지기 때문이다. 또한 냉매유량에 대한 실험값과 예측값은 0.64~10.9% 이내에서 좋은 일치를 보였다. Fig. 3에 나타낸 것처럼, 모세관 길이가 증가할수록 냉각압력은 증가하는 것을 알 수 있다. 이는 증발온도가 일정한 경우 모세관 길이가 증가할수록 냉매유량이 감소하여 압축기 토출측 온도(압력)가 상승하기 때문이다. 그리고 냉각압력에 대한 실험값과 예측값의 비교 결과, 실험값이 예측값보다 약간 낮게 나타났으며 실험값과 예측값은 1.04~3.7% 이내에서 좋은 일치를 보였다. 따라서 본 연구에서는 수송기계용 $CO_2$ 열펌프 단열 모세관에 대한 기초설계 자료로서, 냉각압력, 증발온도, 모세관 직경, 냉매유량 등의 조건으로부터 모세관 길이를 계산해낼 수 있는 예측 상관식을 제안하였다.

• Journal of the Korean Magnetics Society
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• v.10 no.2
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• pp.54-61
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• 2000

The structural and magnetic properties of sputtered CoNbZr alloy films were investigated. In the as-deposited $Co_{87.0}$N $b_{8.5}$Z $r_{4.5}$ film deposited at 2 mTorr and 130 W, we observed the minimum coercivity of 1.75 Oe, the maximum resistivity of 3000 $\mu$Ω.cm and permeability of 1095 at 100 MHz. As the Ar pressure or the RF input power increased, the permeability of films at 100 MHz decreased and the coercivity increased because of the development of columnar structure and the formation of unstable amorphous phase. Permeability lower than 100 and coercivity of 60 Oe were observed in film deposited at 1 mTorr or 190 W due to the formation of crystalline phase. Magnetic anisotropy field of as-deposited films could be reduced by rotating field annealing for 120 minutes at 30$0^{\circ}C$. After the annealing, the anisotropy field (Hk) decreased from 1.43 Oe to 0.3 Oe and the permeability increased from 1095 to 1345 because defects in as-deposited films were eliminated by the annealing.aling.

• Journal of the Korean Applied Science and Technology
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• v.4 no.2
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• pp.35-42
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• 1987

인삼, 들깨 기름, 칼슘 및 마그네슘이 함유되어 있는 식이로 사육한 토끼의 혈장 콜레스테롤과 HMG-CoA reductase의 활성을 조사하였다. 간에 포함되어 있는 HMG-CoA reductase의 활성은 인삼과 들깨 기름 및 마그네슘 첨가 식이군에 있어서 증가되었으며 혈장 콜레스테롤의 농도는 감소되었다. 혈장 LDL-콜레스테롤은 대조군보다 감소하였으나 HDL-콜레스테롤은 증가되었다. 또한 베타 글로블린의 분포도 인삼과 마그네슘 및 들깨 기름을 첨가 급여한 실험군에 있어서 가장 낮았으며, ${\alpha}$-2-글로블린은 대조군에 비하여 가장 높은 값을 보였다. 전해질은 $K^+$은 인삼 첨가로 감소 되었으나 $Na^+$은 증가되었다. 혈장 마그네슘의 농도는 인삼의 첨가로 변화가 없었지만 칼슘과 들깨 기름 및 인삼 첨가식이로 마그네슘의 농도가 더 증가되었다. 혈장 칼슘의 농도는 마그네슘과 인삼을 첨가한 식이군에 있어서 감소하였다.

• New & Renewable Energy
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• v.5 no.2
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• pp.15-24
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• 2009

As new small scale LFG (landfill gas) energy project model which can improve economic feasibility limited due to the economy of scale, LFG-Microturbine combined heat and power system with $CO_2$ fertilization into greenhouses was proposed and investigated including basic design process prior to the system installation at Gwang-ju metro sanitary landfill. The system features $CH_4$ enrichment for stable microturbine operation, reduction of compressor power consumption and low CO emission, and $CO_2$ supplement into greenhouse for enhancement plant growth. From many other researches, high $CO_2$ concentration was found to enhance $CO_2$ assimilation (also known as photosynthesis reaction) which converts $CO_2$ and $H_2O$ to sugar using light energy. For small scale landfills which produce LFG under $3\;m^3$/min, among currently available prime movers, microturbine is the most suitable power generation system and its low electric efficiency can be improved with heat recovery. Besides, since its exhaust gas contains very low level of harmful contaminants to plant growth such as NOx, CO and SOx, microturbine exhaust gas is a suitable and economically advantageous $CO_2$ source for $CO_2$ fertilization in greenhouse. The LFG-Microturbine combined heat and power generation system with $CO_2$ fertilization into greenhouse gas to enhance plant growth is technologically and economically feasible and improves economical feasibility compared to other small scale LFG energy project model.