• 한국식품영양과학회지
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• 제39권7호
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• pp.1011-1017
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• 2010

본 연구에서는 감자튀김 횟수에 따른 각종 식용유지의 화학적 특성 변화를 측정하였다. 식용유지로서는 sunflower oil(SO), canola oil(CO) 및 frying oil(FO)을 사용하였으며, 튀긴 감자에서 추출한 기름의 지방산 조성 변화와 산화 안정성에 대하여 실험하였다. 튀긴 감자에서 추출한 기름의 산화정도는 산가와 과산화물가를 측정하였다. CO 및 FO를 사용하여 튀긴 감자에서 추출한 기름에 대한 산가는 튀김 횟수가 30회의 경우 초기보다 각각 0.20, 0.17 증가한 결과를 나타내었다. SO의 산가는 CO와 FO에 비하여 그 값이 낮게 나타났다. 과산화물가 측정 결과는 일률적으로 증가하지는 않았다. 지방산 조성 변화에 대하여 측정한 결과 SO 및 FO를 사용하여 감자를 튀긴 경우 튀김 반복횟수가 증가할수록 oleic acid 함량은 감소하고 linoleic acid 함량은 증가하였다. 벤조피렌 생성 유무 측정 결과는 SO, CO 및 FO에서 튀김 초기와 반복횟수에 따라서 큰 변화는 나타나지 않았다. 이러한 결과 튀김에 사용한 식용유지 종류 및 튀김 반복 횟수에 따라서 지방산 조성에 변화가 나타나며 그로 인하여 유지의 산화 안정성에 영향을 미침을 알 수 있었다.

• Journal of Welding and Joining
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• 제33권4호
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• pp.17-23
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• 2015

Laser-gas metal arc hybrid welding has been considered as an alternative process of gas metal arc welding for offshore pipe laying. Fiber delivered high power lasers which enable deep penetration welding were recently developed but high power welding characteristics were not fully understood yet. In this study, the influence of shielding gas composition on welding phenomena in high power laser welding was investigated. Bead shapes, melt ejection and dropping were observed after autogenous laser welding with 100% Ar, Ar-20% $CO_2$, Ar-50% $CO_2$, and 100% $CO_2$ shielding gas. Process parameter window was widest with Ar-50% $CO_2$ shielding gas and the penetration was deepest with 100% $CO_2$ shielding gas. The melt dropping was not observed when Ar-50% $CO_2$ or 100% $CO_2$ shielding gas was supplied.

• 한국미생물·생명공학회지
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• 제1권1호
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• pp.25-30
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• 1973

본 연구는 1971년과 1972년 9월 25일에 수확한 흥옥과 동년 10월 25일에 수확한 국광을 시료로하여 이들 사과의 저장에 있어서 환경압력 및 환경기체조성이 사과조직내 기체조성과 호흡 및 ethylene 생성에 미치는 영향을 규명하기 위하여 실험하였던 바 그 결과는 다음과 같다. 1. 과실조직내 기체량은 환경압력에 비례적으로 변화하며, 환경압력이 사과의 조직내 기체조성 및 기체량에 현저하게 영향을 미쳤다. 2. 조직내 $CO_2$발생량의 증가는 조직내 $O_2$ 소비량에 관련되며, 그러므로 내부 $O_2$ 소비의 감소되는 시기와 호흡에 있어서 climacteric rise의 시기와 일치하였다. 3. $CO_2$ 발생량의 증가는 ethylene 생성 후에 나타나며 그리고 상압구의 이와 같은 현상은 감압구에 잇달아 일어난다. 4. 감압저장에 있어서도 저산소농도와 고탄산가스농도의 조절로써 CA효과를 얻을 수 있다.

• 한국자동차공학회논문집
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• 제14권3호
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• pp.170-177
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• 2006

Hydrogen can extend the lean misfire limit to a large extent when it is mixed with conventional fuels for a spark ignition engine. In this study, hydrogen-enriched gaseous fuels by reforming process were simulated according to their proportions of $H_2$, CO, $CO_2$ and $N_2$ gases. Pure hydrogen and two different hydrogen-enriched gaseous mixtures(A-, B-composition) were tested for their basic effects on the engine performances and emissions in a single cylinder research engine. A- and B-composition showed different results from 100% $H_2$ addition because air/fuel mixtures were more diluted by their additions. Even though the energy fraction of reformed gases was increased, combustion stabilities and lean misfire limits were not sensitively improved. It means that combustion augmentation by $H_2$ addition was offset by the charge dilution of $N_2$ and $CO_2$. In addition, the low flammability of CO gas deteriorated thermal efficiencies. CO emission was drastically increased with B-composition which included higher CO component. However, $NO_x$ was reduced as energy fraction($X_e$) rised except for the case of 100% $H_2$ addition at $\lambda=1.2$ and was, for A-composition, lowered to a factor of ten when compared with that of $H_2$ addition. HC emissions were largely influenced by $COV_{imep}$ due to misfire and partial burns.

• Journal of Microbiology
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• 제35권2호
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• pp.127-133
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• 1997

Biosynthesis of polyhydroxybutyrate and copolymer consisting of 3-hydroxybutyrate and 3-hydroxyvalerate [poly(3HB-co-3HV)] by Bacillus thuringiensis R-510 grown with glucose or with mixtures of glucose and propionate was investigated. n-Alkanoic acids other than propionate were not precursors of 3HV units. The fraction of 3HV unit in the copolymer increased from 0 to 84 mol% of 3HV. Polymer yield decreased as the fraction of propionate was increased but the molecular weight distribution was not affected by the composition of carbon substrate. The minimum melting temperature (around 65.deg.C) of poly (3HB-co-3HV) copolymers was observed for the polymer bearing approximately 35 mol% of 3HV. Polyhydroxyalkanoates production by this organism was not dependent on nutritional limitation, but remarkably influenced by dissolved oxygen concentration in the culture medium. Low level of dissolved oxygen concentration prevented spore formation in the cells and stimulated the synthesis of polyhydroxyalkanoate. The composition of poly (3HB-co-3HV) produced by B. thuringiensis R-510 lyhydroxyalkanoate. The composition of poly(3HB-co-3HV) propduced by B. thuringiensis R-510 varied according to the growth time. However, there was no evidence that polymers isolated from cells were mixtures of immiscible polymers.

• Biotechnology and Bioprocess Engineering:BBE
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• 제8권6호
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• pp.360-367
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• 2003

Our research objectives are to determine under what conditions microalgal-based $CO_2$capture from flue gases is economically attractive. Specifically, our objective here was to select microalgae that are temperature, pH and flue gas tolerant. Microalgae were grown under five different temperatures, three different pH and five different flue gas mixtures besides 100% $CO_2$(gas concentrations that the cells were exposed to ranged 5.7-100% $CO_2$, 0-3504ppm SO$_2$, 0-328ppm NO, and 0-126ppm NO$_2$). Our results indicate that the microalgal strains tested exhibit a substantial ability to withstand a wide range of temperature (54 strains tested), pH (20 strains tested) and flue gas composition (24 strains tested) likely to be encountered in cultures used for carbon sequestration from smoke stack gases. Our results indicate that microalgal photosynthesis is a limited but viable strategy for $CO_2$capture from flue gases produced by stationary combustion sources.

• 한국표면공학회지
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• 제28권6호
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• pp.352-360
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• 1995

The effect of electrolysis conditions on the composition, the magnetic properties and the preferred orientation of Ni-Fe-Co alloy deposits was investigated using the sulfate-chloride bath paddle agitated. Cathode current efficiency increases with the current density, showing the different tendency of the variation from that of the Ni-Fe electrodeposits. The Co content of the deposits decreases with increasing current density, while the content of Ni and Fe is shown to be minimum or maximum at 3A/$dm^2$ respectively. The Ni/Fe ratio of the alloy deposits is lower than that of Ni-Fe deposits. The coercive force($H_c$) of the deposits increases with the Co content in deposit, showing the relatively low value in the range of 1.8~5.0Wt.% Co. The anisotropy field ($H_k$) of the deposits is higher than that of Ni-Fe alloy deposits, The preferred orientation of the deposits is generally (200), but the orientation factor(R) changes with both the increase of current density and the magnetic field applied during deposition.

• Journal of Nutrition and Health
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• 제34권6호
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• pp.626-636
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• 2001

To compare the effect of three kinds of n-3 fatty acids-eicosapentaenoic acid(EPA), docosahexaenoic acid(DHA) and perilla oil (PO)-on serum and liver lipid levels and fatty acid composition of liver phospholipid(PL) at low fat level(5%, w/w), 4-weeks old Sprague-Dawley rats were fed with one of five different oil diets for 4 weeks. Beef tallow(BT) and corn oil(CO) was used as control for sturated or n-6 fatty acid respectively. Se겨m concentrations of cholesterol(TC) and phospholipid(PL) were lower in PO DHA and EPA groups than in BT and CO groups. HDL-cholesterol levels were higher in CO and PO groups than in EPA, DHA and BT groups. Liver PL concentrations were higher in DHA and EPA groups than in CO, PO and BT groups, but liver TC and heal PL and TC concentrations did not show any significant difference among groups. Hepatic fatty acid composition of phosphatidylcholine (PC) and phosphatidylethanolamine (PE), two major phospholipids in liver, reflected their dietary fatty acid composition. In PC and PE, total percentage own-6 series was higher in CO group than in any other groups, and that own-3 series was higher in DHA and PO groups than in EPA, CO and BT groups. Moreover, the ratio of 20 : 4/18 : 2 was lower in PO and DHA groups than in EPA, CO and BT groups. On the contrary, the percentage of C22 : 6 was lower in EPA, CO and BT groups than in PO and DHA groups. These results revealed that n-3 series(EPA, DHA and PO) were more effective in lowering um lipids than n-6 fatty acids or saturated fatty acid. Based on the results of fatty acid composition of hepatic phospholipid, we suggest that the dietary effect of PO and DHA on antiatherogenic characteristics seems to be similar extent. In addition, the effect of EPA might not be significantly different from that of BT or CO in the view of eicosanoids production from the precursor fatty acid. These difference of hepatic fatty acid composition might come from other characteristics of dietary oil as well as the type of unsaturation, not from the carbon chain length or the degree of unsaturation of n-3 fatty acid.

• Bulletin of the Korean Chemical Society
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• 제17권9호
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• pp.794-798
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• 1996

Solid solutions of the nonstoichiometric Dy1-xSrxCoO3-y system with the compositions of x=0.00, 0.25, 0.50, 0.75, and 1.00 have been synthesized by the solid state reaction at 1000 ℃ under atmospheric air pressure. The crystallographic structures of the solid solutions are analyzed by the powder X-ray diffraction patterns at room temperature. The analyses assign the compositions of x=0.00 and 0.25 to the orthorhombic system with space group of Pbnm/D2h16, the compositions of x=0.50 and 0.75 to the tetragonal system like a typical SrCoO2.86, and the composition of x=l.00 or SrCoO2.50 to the brownmillerite type system with space group of I**a. The reduced lattice volumes increase with x value due to the larger radius of Sr2+ ion than that of Dy3+ ion. The mole ratio of Co4+ ion to total Co ion with mixed valence state between Co3+ and Co4+ ions at B sites or τ value has been determined by an iodometric titration. All the samples except for the DyCoO3 compound show the mixed valnce state and thus the composition of x=0.50 has the maximum τ value in the system. The oxygen vacancies increasing with x value are randomly distributed over the crystal lattice except for the composition of x=l.00 which have the ordering of the oxygen vacancies. The nonstoichiometric chemical formulas of the Dy1-xSrxCo3+1-τCo4+τO3-(x-τ)/2 system are formulated from the x, τ, and y values. The electrical conductivity in the temperature range of 100 to 900 K increases with τ value linearly because of positive holes of the Co4+ ions in π* band as a conducting carrier. The activation energy of the x=0.50 as Ea=0.17 eV is minimum among other compouds. Broad and high order transition due to the overlap between σ* and π* bands broadened by the thermal activation is observed near 1000 K and shows a low temperature-semiconducting behavior. Magnetic properties following the Currie-Weiss law show the low to high spin transition in the cobaltate perovskite. Especially, the composition of x=0.75 presents weak ferromagnetic behavior due to the Co3+-O2--Co4+ indirect superexchange interaction.

• 한국결정성장학회지
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• 제4권1호
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• pp.57-62
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• 1994

FZ법을 이용하여 $YbFeCoO_4$ 단결정을 성장하였다. 결정 성장은 공기분위기 중에서 이루어졌으며, 성장 속도는 1~2mm/hr로 조절하였으며, 성장 초기는 $YbReO_3$와 CoO로 분해 되었으나 용융 후 액상의 조성이 변화됨에 따라 $YbFeCoO_4$ 단일사의 단결정이 육성되었다.결정의 성장 방향은 c축에 수직으로 성장하였으며 다결정의 종자 결정을 이용하여 용이성장축으로 성장된 결정의 성장 방향은[110]방향이었다.