• Ocean and Polar Research
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• 제34권3호
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• pp.305-323
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• 2012

The ocean's response to the Pinatubo and 1259 volcanic eruptions was investigated using an ocean general circulation model equipped with an energy balance model. Volcanic eruptions release gases into the atmosphere which increases the aerosol optical depth and acts to reduce the incoming short-wave radiation. For example, there was a huge volcanic eruption (Pinatubo) in 1991 which reduced the global mean radiative forcing by about 3 W $m^{-2}$. Two numerical experiments were simulated. The first experiment features the Pinatubo eruption and the second experiment simulates the much larger volcanic eruption that occurred in 1259 when the radiative forcing was reduced by 7 times compared to the Pinatubo event. With the reduced radiative forcing due to the Pinatubo eruption at about 3 W $m^{-2}$ and 1259 eruption at about 21 W $m^{-2}$, the global mean sea surface temperature (SST) decreased to its lowest in the second year after each event by about $0.4^{\circ}C$ and $1.6^{\circ}C$, respectively. Sea surface salinity (SSS) increased substantially in the northern North Pacific, northern North Atlantic, and the Southern Ocean. The reduced SST together with SSS increased ocean convection, which yielded an increase in North Atlantic Deep Water, Antarctic Bottom Water, and North Pacific Intermediate Water production and their outflows. The increase in overturning circulation eventually increased the pole-ward ocean heat fluxes. In conclusion, huge volcanic eruptions perturb the ocean substantially and their hallmarks last for more than a decade, confirming the importance of volcanic eruptions in illustrating the decadal-climate variability recorded in the paleoclimate proxy data for the past million years.

• 한국식품과학회지
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• 제30권5호
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• pp.1140-1145
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• 1998

대황추출물, 황련추출물, 지르코니움계 은치환무기 이온교환체 등의 항균성 소재를 1% 농도로 함유시킨 LDPE 필름($O_2$, 투과도 : $68{\sim}80\;mL/m^2$ atm hr, $CO_2$ 투과도 : $304{\sim}360\;mL/m^2$ atm hr)을 사용하여 200 g 단위의 딸기에 대해서 환경기체조절포장을 실시하고 $5^{\circ}C$에서 저장하면서 포장내 기체조성, 미생물 증식, 물리화학적 품질변화를 측정하였다. 또한 대황추출물 함유 필름의 포장에 0.5 mm의 핀홀을 2개 낸 세공성 포장, 항균제 무첨가의 대조구 LDPE 밀봉포장, PVC wrap 포장과도 비교하였다. 항균성 LDPE 필름은 포장된 딸기의 총균수, 유산균수, 효모수에서 미생물의 생육을 억제하였고, 밀봉포장될 때 4% 이하의 낮은 $O_2$ 농도 및 $6.3{\sim}9.0%$의 $CO_2$ 농도의 변형기체조성을 유지하였다. 포장필름의 미생물생육억제와 변형기체의 복합적인 상승 효과로 인해 항균성 LDPE 밀봉포장은 대조구 LDPE 포장, 통기성의 PVC wrap 및 세공성 핀홀 포장에 비해 현저하게 낮은 부패율을 보였다. 그리고 이러한 포장은 딸기의 경도 유지에도 긍정적인 효과를 가짐과 아울러 다른 물리화학적 변화에도 부정적인 영향을 주지 않았다.

• 한국식품과학회지
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• 제35권5호
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• pp.865-870
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• 2003

신고 배의 저장성에 환경기체조성이 미치는 영향을 확인하기 위하여, 배 과실을 $0^{\circ}C$의 static CA조건(3kPa $O_2$+1 kPa $CO_2$, 1 kPa $O_2$+5 kpa $CO_2$, 1 kPa $O_2$+1 kPa $CO_2$)과 air(21 kPa $O_2$+0 kPa $CO_2$) 조건에서 8개월간 저장하면서 이화학적 및 관능적 품질특성의 변화를 조사하였다. 저장 중 중량감소는 CA조건에서 상당히 억제되었지만 기체조성비에 따른 차이는 없었다. 과육경도의 감소는 산소농도가 낮고 이산화탄소 농도가 높은 1kPa $O_2$+5 kpa $CO_2$ 조건에서 가장 억제되었다. 과피의 lightness는 경시적으로 점차 감소하였고, chroma는 저장말기에 약간 감소하였으며, hue는 거의 변화지 않는 경향이었으나 저장조건과는 무관하였다. 가용성 고형물 함량은 CA조건에서는 변동이 없었으나 air조건에서는 수분손실로 인해 저장말기에 증가하는 경향이었다. 적정산도와 pH는 저장초기에 비교적 급격히 감소하고 증가하는 경향이었으나 저장조건의 영향은 크게 받지 않았다. 비타민C 함량은 저장조건에 따른 차이가 없이 경시적으로 극미하게 감소하는 경향이었다. 장해과 발생은 CA조건에서 억제되었으며 1 kPa 산소조건에서 더욱 억제되었다. 관능적 품질특성인 appearance, aroma, sweetness 및 texture는 CA저장 과실이 air 저장 과실보다 우수하게 평가되었으나 CA조건에 따른 유의적인 차이는 없었다.

• Journal of Advanced Marine Engineering and Technology
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• 제32권8호
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• pp.1141-1148
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• 2008

One of the methods to increase the efficiency of an engine is to expand pressures obtained from combustions equal to the pressure of atmosphere as much as possible and then convert thermal energy into mechanical energy also as much as possible. In this research, the Diesel cycle was thermodynamically interpreted to evaluate the possibility of high efficiency by converting Diesel engines to the Atkinson cycle, and general cycle features were analyzed after comparing these two cycles. In the case of fuel air the Diesel-Atkinson cycle considering intake and exhaust similar to real cycles, the value of thermal efficiency and average effective pressure increased, though their values were smaller than those of standard air amount cycle, when expansion compression ratio increased. When normal Diesel engines of which compression stroke and expansion stroke are all the same, was converted to the Atkinson cycle by changing the time of intake value close, combustion pressure reduced due to reduced expansion compression ratio and intake air amount due to decreased effective cycle volume.

• Korean Chemical Engineering Research
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• 제58권4호
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• pp.658-664
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• 2020

Zeolite HY is wet impregnated with Ni (0.1, 0.3, 0.4, 0.5 wt%), Pt (0.1 wt%) and reduced in presence of hydrogen to form nanosized particles of Ni and Pt. All the catalysts were characterized by XRD, TEM, ESCA, NH₃-TPD, Pyridine adsorbed FT-IR and BET. Characterization results confirm that the Ni and Pt fractions effectively rehabilitated the physio-chemical properties of the zeolite HY catalysts. Further, all the reduced catalyst were screened with hydroisomerization of m-xylene at LHSV = 2.0 h^-1 in the temperature range 250-400 ℃ in steps of 50 ℃ in hydrogen atmosphere (20 ml/g). The addition of Ni to Pt catalyst increases hydroisomerization conversion, as well as maximizes p-xylene selectivity by restricting the pore size. The increasing trend in activity continues up to 0.3 wt% of Ni and 0.1 wt% Pt addition over zeolite HY. The increasing addition of Ni increases the total number of active metallic sites to exposed, which increases the metallic sites/acid sites ratio towards the optimum value for these reactions by better balance of synergic effect for stable activity. The rate of deactivation is pronounced on monometallic catalysts. The results confirm the threshold Ni addition is highly suitable for hydroisomerization reaction for product selectivity over Ni-Pt bimetallic/support catalysts.

• 한국세라믹학회지
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• 제44권12호
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• pp.727-732
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• 2007

In order to fabricate a highly performing cathode for low-temperature type solid oxide fuel cells working at below $700^{\circ}C$, electrode microstructure control and electrode polarization measurement were performed with an electronic conductor, $La_{0.8}Sr_{0.2}MnO_3$ (LSM) and a mixed conductor, $La_{0.6}Sr_{0.4}Co_{0.2}Fe_{0.8}O_3$(LSCF). For both cathode materials, when $Sm_{0.2}Ce_{0.8}O_2$ (SDC) buffer layer was formed between the cathode and yttria-stabilized zirconia (YSZ) electrolyte, interfacial reaction products were effectively prevented at the high temperature of cathode sintering and the electrode polarization was also reduced. Moreover, cathode polarization was greatly reduced by applying the SDC sol-gel coating on the cathode pore surface, which can increase triple phase boundary from the electrolyte interface to the electrode surface. For the LSCF cathode with the SDC buffer layer and modified by the SDC sol-gel coating on the cathode pore surface, the cathode resistance was as low as 0.11 ${\Omega}{\cdot}cm^2$ measured at $700^{\circ}C$ in air atmosphere.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집
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• pp.375-378
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• 2002

We investigated the reduction of etching damage by additive O$_2$ in etching gas and recovery of etching damage by O$_2$ annealing. The PZT thin films were etched using additive Ar or O$_2$ into Cl$_2$/CF$_4$ gas mixing ratio of 8/2. In order to recover ferroelectric properties of PZT thin films after etching, the etched PZT thin films were annealed at 600 C in O$_2$ atmosphere for 10 min. The remanent polarization is decreased seriously and fatigue is accelerated in the PZT sample etched in Ar/(C1$_2$+CF$_4$) plasma, whereas these characteristics are improved in O$_2$/(Cl$_2$/CF$_4$). From x-ray photoelectron spectroscopy (XPS) analysis, the intensities of Pb-O, Zr-O and Ti-O peaks are changed and the etch byproducts such as metal chloride and metal fluoride are reduced by O$_2$ annealing. From electron probe micro analyzer (EPMA) and auger electron spectroscopy(AES), O$_2$ vacancy is observed after etching. In x-ray diffraction (XRD), the structure damage in the additive O$_2$ into C1$_2$/CF$_4$ is reduced and the improvement of ferroelectric behavioral annealed sample is consistent with the increase of the (100) and (200) PZT peaks.

• 한국의류산업학회지
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• 제22권1호
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• pp.119-129
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• 2020

Unlike synthetic dyes, natural dyes do not affect the human body or create atmosphere pollution that are also mothproof, antibiotic and sterilized. This study examined the changes in dye adsorption properties according to mordant types and mordanting method to qualify trends using sage and rosemary extracts. Dyeability of sage extract is often similar to rosemary extract regardless of dyeing conditions. Dyeing properties of herb colorants on cotton, silk and wool fiber and effect of dyeing conditions on dye uptake were also compared. Dyed fabric showed a yellowish color and the dyeing affinity was somewhat good with rosemary extract. The surface color of the dyed fabrics was darkened by mordant treatment. The K/S value of herb colorants of protein fiber was higher than cellulose fiber. The concentration of mordant having the highest dyeing affinity was different from the mordant type. Regardless of the type of fiber, the K/S value of premordanting was the highest in mordanting method, and the K/S value of simultaneous mordanting indicated no noticeable mordant effect. The fastness of washing of silk fabric was reduced the most by mordant treatment. The lightfastness was reduced in Al mordant treatment regardless of the type of fiber. The lightfastness of wool increased somewhat by mordant treatment.

• Toxicological Research
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• 제6권2호
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• pp.143-157
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• 1990

Effective measure to prevent oxygen toxicity is greatly required as there increase chances to be exposed to high oxygen pressure, for example, space travel, deep sea diving and hyperbaric oxygen therapy. In the present study, in an attempt to evaluate glutathione and chlorpromazine as protective agents against oxygen toxicity, effects of the agents were tested on various toxicities (death rate, convulsion rate, time to convulsion, increase in weight of lung and brain and pathological changes in the organs) observed in rats exposed to 5 Absolute Atmosphere (ATA) of 100% oxygen for 120 minute. Glutathione reduced mortality rate and convulsion rate and also markedly suppressed the increase in lung and brain weight. The pathological changes observed in these organs were ameliorated by administration of glutathione. Chlorpromazine also reduced mortality rate but its effects appeared to be limited mainly to pulmonary toxicities. Thus glutathione seems to be more effective than chlorpromazine as a protective agent. The results obtained may support that oxygen toxicity is mediated by oxygen free radicals.

• 한국분말재료학회지
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• 제14권2호
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• pp.101-107
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• 2007

Ultrasonic-milling of metal oxide nanopowders for the preparation of tungsten heavy alloys was investigated. Milling time was selected as a major process variable. XRD results of metal oxide nanopowders ultrasonic-milled for 50 h and 100 h showed that agglomerate size reduced with increasing milling time and there was no evidence of contamination or change of composition by impurities. It was found that nanocomposite powders reduced at $800^{\circ}C$ in a hydrogen atmosphere showed a chemical composition of 93.1W-4.9Ni-2.0Fe from EDS analysis. Hardness of sintered part using 50 h and 100 h powder samples was 399 Hv and 463 Hv, respectively, which is higher than the that of commercial products (330-340 Hv).