• Korean Chemical Engineering Research
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• 제45권3호
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• pp.219-225
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• 2007

비이온 계면활성제 $C_{12}E_8$ 수용액의 탄화수소 오일에 대한 가용화도(equilibrium solubilization capacity)를 $30^{\circ}C$에서 기체 크로마토그래피(GC)를 이용하여 측정하였다. 탄화수소 오일의 가용화도를 실험에 사용한 계면활성제의 농도로 나눈 값으로 표시한 molar solubilization ratio(MSR)는 순수한 단일 성분의 탄화수소 오일 경우, 탄화수소 오일의 탄소수(ACN)가 증가함에 따라 거의 선형적으로 감소함을 알 수 있었다. 한편 탄화수소 오일의 이성분 시스템은 사용한 두 탄화수소 오일의 탄소수(alkane carbon number, ACN) 차이에 따라 선택적 가용화 혹은 비선택적 가용화 경향을 나타내었다. 본 연구에서 가용화도 실험을 수행한 n-octane/n-nonane과 n-nonane/n-decane 혼합물 시스템의 경우, 비선택적 (non-selective) 가용화 경향을 나타내었으며, 반면에 n-octane/n-decane 혼합물 시스템의 경우에는 선택적(selective) 가용화 경향을 따르는 것을 GC 분석 결과로부터 확인할 수 있었다.

• KSBB Journal
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• 제10권1호
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• pp.38-45
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• 1995

Aspergillus oryzae에서 A. nidulans의 glyceral d dehyde-3-phosphate dehydrogenase (gpdA)와 trpC, prmoter의 발현 능력 을 E. coli lacZ gene fusion을 이용하여 비교.분석하였다. A. oryzae 내에서 발현된 E. coli $\beta$galactosidase의 specific activIty를 조사하여 본 결과, gpdA promoter를 가지는 transformant들 에서는 2,000unit/ug of protem 정도의 activity를 보이는 반면, trpC, promater를 가지고 있는 transformant들에서는 10.5~52.3unit/ug of protein 정도의 activity를 보였다. 이 결과로부터 A. oryzae 내에서 A. nidulans의 gpdA promoter가 trpC, promoter에 비해 70 배 정도 더 강한 발현 능력을 보이고 있음을 알 수 있다. Western blot 분석에서도 gpdA promoter를 가지고 있는 transf ormant에서 더 많은 E. coli $\beta$-galactosidase가 발현된 것 을 보여 주고 있다. 또한 southern blot 분석에서는 이러한 강한 발현이 transform된 plasmid의 copy number와 상관 없음을 보여주고 있다.

• Carbon letters
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• 제11권4호
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• pp.293-297
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• 2010

To investigate new potential application of a clay material for C/C composites, illite added C/C composites were prepared with various illite contents. The improvement of filler effect by illite size reduction was also investigated using wet ballmilling by evaluating illite/phenolic resin infiltration using bulk density and porosity measurements, chemical structural changes of the composites using XRD, and thermal oxidation stability in air of the composites using TGA. The size reduction of illite resulted in narrower particle size distribution and improved illite infiltration into carbon preform. And the resultant C/C composites prepared with illite had even more improved thermal oxidation stability in air, showing more increased IDTs up to $100^{\circ}C$, compared to those of the C/C composites with pristine illite, due to the SiC formation through carbothermal reduction between illite and carbon materials. The illite induced delay in oxidation of the illite-C/C composites was also observed and the delayed oxidation behavior was attributed to the layered structure of illite, which improved illite/phenol resin infiltration. Therefore, the potential use of illite as filler to improve oxidation stability of C/C composite can be promising. And the size reduction of illite can improve its effect on the desired properties of illite-C/C composites even more.

• 한국식품과학회지
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• 제29권4호
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• pp.771-775
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• 1997

본 연구는 병원성 Escherichia coli O157:H7 균주에 의한 식중독을 미연에 예방하고자 우육에 본 균주를 오염, 동결시켜 전자선에 의한 살균효과를 조사하였다. $37^{\circ}C$에서는 배양 16시간째에 최대균수를 나타내었고 $4^{\circ}C$에서는 균주의 증식이 거의 없었다. E. coli O157:H7 균주는 대수기나 정지기 모두가 $0^{\circ}C$ (chilled)와 $-18^{\circ}C$ (frozen)에서 배양시 약 $10^{7}\;CFU/mL$의 균수를 나타내었고 $-18^{\circ}C$에서는 $20^{\circ}C$ 보다 균주의 사멸율이 높았다. 동결육에 오염된 E. coli O157:H7 균주의 방사선 감수성은 $D_{(10)}$ 값이 0.45 kGy, 불활성화계수가 $3{\sim}5\;kGy$에서 $6.67{\sim}11.11$로 각각 나타났다. 본 결과로서 전자선 조사는 동결육에 오염된 E. coli O157:H7 균주의 제거방법으로 매우 효과가 있었다.

• 대한기계학회논문집
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• 제19권8호
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• pp.2012-2021
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• 1995

An experimental study was performed for the analysis of dynamic characteristics of refrigeration system by controlling the evaporator superheat. Experimental data have been taken utilizing two different devices, thermostatic expansion valve(T.E.V.) and electronic expansion valve(E.E.V.), for the control of the evaporator superheat. The ranges of parameters, such as superheat, mass flow rate of refrigerant and inlet temperature of evaporator were 5-30.deg. C 90-170 kg/h and 10-25.deg. C, respectively. The data taken from the T.E.v.and E.E.v.were discussed with the control of the superheat, pressure drop, refrigerating capacity, compression work, evaporating temperature, condensing temperature and COP affecting performance characteristics of refrigeration system. In case of the refrigerant flow control with T.E..V., the superheat and pressure drop of the evaporator varied periodically, but the control with E.E.V., the parameters were very stable. In E.E.v.control, refrigerating capacity, compression work and evaporating temperature were decreased with increasing superheat, and the highest COP was obtained in the range of superheat from 5.deg. C to 15.deg. C.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.17-17
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• 2009

Piezoelectric single crystals in the ternary MPB PMN-PZ-PT system with high $T_cs$ ($T_c$ > $200\sim300^{\circ}C$) and $E_cs$($E_c$>5~10 kV/cm) were fabricated by the cost-effective solid-state crystal growth (SSCG) technique. Chemically uniform PMN-PZT single crystals were successfully grown up to 60 mm by the SSCG method and their dielectric and piezoelectric properties characterized. Compared to Bridgman PMN-PT single crystals, the high $T_c/E_c$ PMN-PZT single crystals were found to exhibit a much wider usage range with respect to electric field as well as temperature, and thus become best candidates for medical transducers, actuators, and naval applications.

• 한국식품저장유통학회지
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• 제2권2호
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• pp.225-232
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• 1995

In order to study the effect of modified atmosphere packaging(M.A.P.) and controlled atmosphere(C. A.) storage on keeping freshness of mushrooms (Agricus-bisporus). Mushrooms was packaged with polyethylene(P.E.) film (40${\mu}{\textrm}{m}$, 60${\mu}{\textrm}{m}$, 80${\mu}{\textrm}{m}$) and C.A. conditions(CO2 concentration of 2%, O2 concentration of 2%) and storage at 0$\pm$1$^{\circ}C$, RH(relative hummidity) 92$\pm$1%. Gas composition in film was changed rapidly at early of storage, but it kept a constant level after 14 days of storage, and then kept at the level of 6~9% CO2 and 2~5% O2. Weight loss was 5% in non-packed mushrooms after 3 days of storage, but P.E. film, CO2 treated, C.A. conditions were 5% after 21 days of storage. Flesh firmness of the mushrooms was continuously decreased throughout storage period and the lowest of flesh firmness changed was 80${\mu}{\textrm}{m}$-P.E. film packing. Discoloration of the piteous of mushrooms appears to be the most Important factors to determine its marketability, L value of it appears to be of the high values at P.E. film packing and C.A. conditions during period. Large amount of ethanol and acetaldehyde were produced from the 7 days during storage, large contents of mannitol and trehalose were at the 14 days and 7 days during storage.

• 한국환경과학회지
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• 제17권4호
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• pp.469-477
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• 2008

The aerobic photosynthetic bacterium, which produces bacterial carotenoids was isolated and identified from coastal marine environments. This bacterium was identified by 16S rDNA sequencing and designated as Erythrobacter longus SY-46. E. longus SY-46 was Gram negative and rod shape, and the optimal culture conditions were $25^{\circ}C$, pH 7.0, and 3.0% NaCl concentration, respectively. The carbon and nitrogen sources required for the optimal growth were lactose and tryptone, respectively. Fatty acid compositions of E. longus SY-46 were $C_{18:1}$(78.32%), v-linolenic acid($C_{18:3n9.12.15c}:3.83%$), margaric acid($C_{17:0}$: 3.38%), palmitic acid($C_{16:0}$: 3.07%), and docosahexaenoic acid($C_{22:6n3}$: 2.21%). In addition, E. longus SY-46 showed the characteristic absorption peaks of bacterial carotenoids(in the region of 450 to 480 nm) and bacteriochlorophyll(770 to 772 nm). Major carotenoids of E. longus SY-46 were polyhydroxylated xanthophylls such as fucoxanthin and zeaxanthin.

• 한국세라믹학회지
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• 제41권10호
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• pp.723-727
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• 2004

Three kinds of $Si_3N_4$ powders (M-11, SN-ESP, and SN-E10) were gas-pressure sintered at $1700-1900^{\circ}C$ for 2 h under 18 atm $N_2$. Their densification behavior was investigated and compared as well as the mechanical properties and microstructure of the resulting ceramics. SN-ESP and SN-E10 started to reach nearly full densification at $1750^{\circ}C$ and showed almost no decomposition up to $1900^{\circ}C$. In contrast, M-11 was not fully densified until $1800^{\circ}C$ and showed about $3\%$ weigh loss at $1900^{\circ}C$ indicating poor thermal stability. SN-ESP and SN-E10 showed much higher strength both at room temperature and $1200^{\circ}C$ than M-11 when fully densified. Compared with SN-ESP, SN-E10 was not only a little better in strength (both at room temperature and $1200^{\circ}C$) and fracture toughness but also much higher in the Weibull modulus due to more interlocked microstructure by well elongated grains.

• 한국전기전자재료학회논문지
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• 제30권11호
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• pp.734-739
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• 2017

We prepared $SnS_x$ thin films on both soda-lime glass (SLG) and molybdenum(Mo)/SLG substrates by a two-step process using a Sn precursor followed by sulfur reaction in rapid thermal annealing (RTA) at different sulfurization temperatures ($Ts=200^{\circ}C$, $230^{\circ}C$, $250^{\circ}C$, and $300^{\circ}C$) and annealing times ($t_s=10min$ and 30 min). The single SnS phase was dominant for $200^{\circ}C{\leq}T_s$<$250^{\circ}C$, while an additional phase of $SnS_2$ was appeared at $T_s{\geq}250^{\circ}C$ alongside SnS. The SnS grains in all the samples showed strong growth along the preferred [040] direction. The band-gap energy ($E_g$) of the films was estimated to be 1.24 eV.