Microstructural evolution in the thickness direction of an oxygen free copper processed by accumulative rollbonding (ARB) is investigated by electron back scatter diffraction (EBSD) measurement. For the ARB, two copper alloy sheets 1 mm thick, 30 mm wide and 300 mm long are first degreased and wire-brushed for sound bonding. The sheets are then stacked and roll-bonded by about 50% reduction rolling without lubrication at an ambient temperature. The bonded sheet is then cut to the two pieces of the same dimensions and the same procedure was repeated on the sheets up to eight cycles. The specimen after 1 cycle showed inhomogeneous microstructure in the thickness direction so that the grains near the surface were finer than those near the center. This inhomogeneity decreased with an increasing number of ARB cycles, and the grain sizes of the specimens after 3 cycles were almost identical. In addition, the aspect ratio of the grains decreased with an increasing number of ARB cycles due to the subdivision of the grains by shear deformation. The fraction of grains with high angle grain boundaries also increased with continuing process of the ARB so that it was higher than that of the low angle grain boundaries in specimens after 3 cycles. A discontinuous dynamic recrystallization occurred partially in specimens after 5 cycles.

본 연구에서는 LSCF/GDC (20 : 80 vol%) 복합 분리막 표면에 LSC/GDC (50 : 50 vol%) 활성층을 코팅한 후 활성층의 열처리 온도, 두께, 침투법을 이용한 STF 도입이 산소투과 특성에 미치는 영향을 고찰하였다. 활성층 도입은 복합 분리막의 산소 투과 유속을 급격히 증진시켰으며 이는 활성층 성분인 LSC/GDC (50 : 50 vol%)가 전자 전도성 및 표면 산소 분해 반응을 증진시켰기 때문이었다. 활성층의 열처리 온도가 900˚C에서 1000˚C로 증가한 경우, 산소 투과 유속은 증가하였고 이는 분리막과 활성층 사이 그리고 활성층의 결정입간 접촉이 증진하여 산소이온과 전자 흐름을 증진시켰기 때문으로 설명되었다. 코팅층의 두께가 약 10μm에서 약 20μm로 증가한 경우, 산소 투과 유속은 오히려 감소하였는데 이는 코팅층의 두께가 증가할수록 기공을 통한 공기 중의 산소 유입이 어려워지기 때문으로 설명되었다. 또한, 코팅층에 침투법을 이용하여 STF를 도입한 경우가 STF를 도입하지 않은 경우 보다 높은 산소 투과 유속을 보였는데 이는 도입된 STF가 산소 분해하는 표면 반응 속도를 촉진시키기 때문이다. 본 연구로부터 LSC/GDC (50 : 50 vol%) 활성층 코팅 및 특성 제어는 LSCF/GDC (20 : 80 vol%) 복합 분리막의 산소투과 증진에 매우 중요함을 확인하였다.

Recently, several approaches have been used to measure the oxygen consumption rates of individual embryos, but relationship between oxygen consumption and pregnancy rates of Hanwoo following embryo transfer has not yet been reported. In this study, we investigated the correlation between oxygen consumption rate and pregnancy rates of Hanwoo embryo using a SECM. In addition to, the expression of apoptosis-related genes was determined using real-time PCR by extracting RNA according to the oxygen consumption of in vivo embryo. First, we found that the oxygen consumption significantly increased in blastocyst-stage embryos (blastocyst) compared to early blastocyst stage embryos, indicating that oxygen consumption reflects the embryo quality (Grade I). The oxygen consumption or GI blastocysts were significantly higher than those of GII blastocysts (10.2x1014/mol s-1 versus 6.4x1014/mol s-1, p＜0.05). Pregnant rate in recipient cow was 0, 60 and 80% in the transplantation of embryo with the oxygen consumption of below 10.0, 10.0~12.0 and over 12.0x1014/mol s-1, respectively. Apoptosis regulatory genes, Hsp-70.1 were significantly increased in over-10.0 group than below 10.0 group but in Caspase-3, Bax and P53 gene, there was no significant difference. In conclusion, These results suggest that measurement of oxygen consumption maybe help increase the pregnant rate of Hanwoo embryos.

미더덕의 집단폐사가 주로 발생하는 여름철 고수온 및 빈산소에 의한 생물학적 지표를 찾아 대량폐사 원인 구명을 위한 기초자료로 활용하기 위하여 수온상승 및 용존산소농도 감소에 따른 미더덕의 생존율, 생리적 반 응 및 조직학적 변화 등을 조사하였다. 수온상승에 따른 생존율은 수온 23􀆆C에서 63.3%, 26􀆆C 에서 56.6%였으며, 수온 29􀆆C에서 노출 6일째 모두 사 망하여 노출 6일 동안의 반수치사 수온은(6day-LT50)은 24.58􀆆C (19.48~35.48􀆆C)였다. 용존산소 농도 감소에 따 른 생존율은 노출 11일째 용존산소농도 4.0 mg L-1에서 20%였으며, 2.0 mg L-1에서는 모두 사망하였고, 반수치사 용존산소 농도 (11day-LC50)는 3.88 mg L-1 (3.29~4.57 mg L-1)였다. 산소소비율과 암모니아질소 배설률은 임계 수온 및 임계용존산소 농도이하에서 감소하였다. 수온 상승 및 용존산소 농도 감소에 따른 미더덕의 새낭, 소화관 및 피낭의 병리조직학적 결과는 각 기관을 구성하고 있는 상피세포층의 증식, 응축 및 괴사, 식세포 및 혈구침윤, 섬모탈락, 근섬유 변성 등의 변성이 공통적 으로 관찰되었다. 미더덕은 수온 24􀆆C 이상, 용존산소 3.8 mg L-1 이하에서 조직학적 병변, 대사율 감소 등으로 환 경변화에 매우 민감한 생물이므로 여름철에 양성되고 있는 미더덕의 양식장관리에 세심한 관리가 요구된다.

In this study, the growth kinetics of sulfur oxidizing bacteria, Acidithiobacillus thiooxidans, and the effect of dissolved oxygen were determined in low pH conditions for the effective removal of high concentrations of hydrogen sulfide. A dual growth kinetic was applied to identify the microbial growth rate at different hydrogen sulfide and oxygen concentrations in the liquid. A modified Monod-Gompertz equation was deemed most appropriate to examine the growth kinetic parameters of A. thiooxidans. The half saturation constants of hydrogen sulfide and oxygen for the modified Monod-Gompertz equation were found to be 0.9 and 1.1 mg/L, respectively. In addition, a bioreactor model, where the Monod-Gompertz equation was modified, was applied to simulate dissolved oxygen concentrations required for the removal of hydrogen sulfide. As a result, the dissolved oxygen concentrations were 0.5, 1.0, 1.5, and 3.3 mg/L, which were necessary to remove hydrogen sulfide to less than 10 ppm at the influent concentrations of 100, 500, 1000 and 3000 ppm, respectively. The required minimum dissolved oxygen concentrations under various conditions including reactor volume, gas retention time, and microbial concentrations can be determined using the numerical model developed in this study.

The effect of oxygen pressure on the synthesis of ZnO nanowires by means of melt-oxidation of an Al-Zn mixture was investigated. The samples were prepared in oxygen ambient for 1 h at 1,000˚C under oxygen pressure ranging from 0.5 to 100 Torr. ZnO nanowires were formed at oxygen pressures lower than 10 Torr. As the oxygen pressure increased from 0.5 to 10 Torr, the width of the nanowires increased, but their length decreased. The ZnO nanowires had a needle shape, which became gradually thinner toward the tip. X-ray diffraction patterns showed that the nanowires had a hexagonal wurtzite structure. However, ZnO nanowires were not observed when the oxygen pressure increased from 10 Torr to 100 Torr. In roomtemperature cathodeluminescence spectra of the ZnO nanowires, the intensity of ultra-violet emission at 380 nm increased with decreasing oxygen pressure, which indicated that the lower the oxygen pressure, the better the crystallinity of the ZnO nanowires.

Metallic Cr film coatings of 1.2μm thickness were prepared by DC magnetron sputter deposition method on c-plane sapphire substrates. The thin Cr films were ammoniated during horizontal furnace thermal annealing for 10-240 min in NH3 gas flow conditions between 400 and 900˚C. After annealing, changes in the crystal phase and chemical constituents of the films were characterized using X-ray diffraction (XRD) and energy dispersive X-ray photoelectron spectroscopy (XPS) surface analysis. Nitridation of the metallic Cr films begins at 500˚C and with further increases in annealing temperature not only chromium nitrides (Cr2N and CrN) but also chromium oxide (Cr2O3) was detected. The oxygen in the films originated from contamination during the film formation. With further increase of temperature above 800˚C, the nitrogen species were sufficiently supplied to the film's surface and transformed to the single-phase of CrN. However, the CrN phase was only available in a very small process window owing to the oxygen contamination during the sputter deposition. From the XPS analysis, the atomic concentration of oxygen in the as-deposited film was about 40 at% and decreased to the value of 15 at% with increase in annealing temperature up to 900˚C, while the nitrogen concentration was increased to 42 at%.

고도정수처리를 위한 관형 세라믹 정밀여과와 이산화티타늄(TiO₂) 광촉매 첨가 PES (polyethersulfone) 구의 혼성공정에서 pH 및 포화산소, 역세척 매체의 영향을 막오염에 의한 저항(Rf) 및 투과선속(J), 총처리수량(VT) 측면에서 물 또는 질소, 산소 역세척 결과를 비교하였다. pH가 증가할수록 Rf는 감소하였고 J과 VT는 증가하였다. 탁도 처리효율은 pH에 상관없이 물 또는 질소 역세척 모두 유사한 값을 보였고, 용존유기물(DOM) 처리효율은 물 역세척 시 일정한 경향을 보이지 않았다. Rf는 공급수를 산소로 포화시킨 무역세척(NBF)에서 포화산소(SO)가 없는 NBF보다 낮게 나타났다. DOM 처리효율도 SO가 있는 NBF에서 SO가 없는 NBF보다 낮게 나타났다. 이러한 결과는 SO가 광촉매 TiO₂와 반응하여 발생된 OH 라디칼이모듈 내에 채워진 물에 의해 희석되었기 때문이다. 역세척 주기 10분에서 물 역세척보다 기체 역세척 시 DOM 처리효율은큰 값을 보였다. 이러한 결과는 기체 역세척이 물 역세척보다 PES 구를 효과적으로 세척함으로써, PES 구에 의한 흡착과 광분해가 활발하게 진행되기 때문이다.

The fumigant activity of phosphine (PH3) and ethyl formate (EF) was determined to all stage of Phthorimaea operculella (Zeller) under high oxygen concentration (50% and 80%). Oxygenated PH3 and EF were tested at two different temperatures (20°C and 4°C) during 7 days. Two oxygenated fumigants were treated with LC10, 30 and 50 values of single fumigant against each stage of P. operculella. At 10% inhibition of hatchability concentration value, inhibition of hatchability of P. operculella eggs was shown 20.3% and 9.2% with 50% and 80% oxygenated PH3 at 20°C at 1 day after treatment, respectively. The fumigant activity of oxygenated PH3 was increased at all stage of P. operculella except eggs both 20°C and 4°C. However, oxygenated EF was determined low fumigant efficacy to hatchability of eggs and emergence rate of pupae. The insecticidal activities of P. operculella larvae and adults were slightly increased mortality rather than single EF. In this result suggests that oxygenated phosphine is effective method for managing P. operculella. But, oxygenated EF is not effective.

Nanotechnology has become one of the fastest developing technologies and recently applied to a variety of industries. Thus, increasing number of nano materials including various nanoparticles would be discharged into wastewater and consequently entering a biological wastewater treatment process. However, the impact of the nano particles on biological wastewater treatment has not been estimated intensively. In this research, we investigated the effect of silica nanoparticle on the oxygen uptake rates (OURs) of activated sludge used in a conventional wastewater treatment process. The inhibition (%) values were estimated from the results of OURs experiments for the silica nanoparticles with various sizes of 10-15, 45-50, and 70-100 nm and concentrations of 50, 250, and 500 ppm. As results, the inhibition value was increased as the size of silica nano particles decreased and the injected concentration increased. The maximum inhibition value was investigated as 37.4 % for the silica nanoparticles with the size of 45-50 nm and concentration of 50 ppm. Additionally, the effect of size and concentration on the inhibition should be considered cautiously in case that the aggregation of particles occurred seriously so that the size of individual particles was increased in aquatic solution.

고도정수처리를 위한 관형 세라믹 정밀여과와 이산화티타늄(TiO2) 광촉매 첨가 PES (polyethersulfone) 구의 혼성공정에서 pH 및 산소 역세척의 영향을 막오염에 의한 저항(Rf) 및 투과선속(J), 총여과부피(VT)의 관점에서 고찰하였다. pH가높아질수록 Rf가 감소하고, J는 증가하는 경향을 보였다. 결과적으로 pH 9에서 최대의 VT를 나타내었다. 탁도의 처리효율은 pH와 무관하게 98.7∼99.0%의 비슷한 처리효율을 보였다. 용존유기물질(DOM)의 처리효율은 pH가 높아질수록 감소하였다.산소와 질소 역세척의 차이를 비교한 결과, Rf,180 값이 산소 역세척 시 질소보다 낮게 나타났고, 초기투과선속(J0)으로 무차원화한 최종투과선속(J180/J0)은 역세척 주기(FT) 10분과 12분을 제외하고 산소 역세척이 질소 보다 높게 유지되었다. 산소 역세척 시 탁도물질의 처리효율은 질소 보다 다소 높게 나타났지만, 그 차이는 미비하다. 질소 역세척 시 DOM의 처리율은 산소보다 높게 나타났다. 또한, 포화산소 조건에서 탁도물질의 처리율은 산소 또는 질소 역세척 경우와 비슷하게 나타났지만, 포화산소가 광촉매와 반응하여 OH 라디칼을 생성하였기 때문에 DOM의 처리효율은 큰 폭으로 증가하였다.

We prepared ethylene vinyl alcohol (EVOH)/graphene oxide (GO) membranes by solution casting method. X-ray diffraction analysis showed that GOs were fully exfoliated in the EVOH/GO membrane. The glass transition temperatures of EVOH were increased by adding GOs into EVOH. The melting temperatures of EVOH/GO composites were decreased by adding GOs into EVOH, indicating that GOs may inhibit the crystallization of EVOH during non-isothermal crystallization. However, the equilibrium melting temperatures of EVOH were not changed by adding GOs into EVOH. The oxygen permeability of the EVOH/GO (0.3 wt%) film was reduced to 63% of that of pure EVOH film, with 84% light transmittance at 550 nm. The EVOH/GO membranes exhibited 100 times better (water vapor)/(oxygen) selectivity performance than pure EVOH membrane.

목적: 본 연구는 trimethylsilyl methacrylate와 titanium silicon oxide 나노입자를 사용하여 친수성 하이드로젤 콘택트렌즈 재질을 중합하고 제조된 친수성 콘택트렌즈의 물리적, 광학적 특성을 분석하여 이들 물질들의 콘택트렌즈 재료로서의 활용도를 알아보았다. 방법: 고분자의 중합은 2-hydroxyethyl methacrylate, methyl methacrylate 및 n-vinyl pyrrolidone과 가교제인 ethylene glycol dimethacrylate를 기본 조합으로 하였으며, 개시제로는 AIBN을 사용하였다. 제조된 렌즈의 물성 변화를 알아보기 위해 trimethylsilyl methacrylate와 titanium silicon oxide를 첨가하여 중합하고 함수율, 굴절률, 산소투과도, 분광투과율을 측정하였다. 결과: 제조된 친수성 콘택트렌즈는 하이드로젤 콘택트렌즈의 기본물성을 만족하였으며, 첨가제인 trimethylsilyl methacrylate의 양이 증가함에 따라 산소투과도는 증가하는 것으로 나타났다. 또한 titanium silicon oxide 나노입자의 첨가는 친수성 렌즈 소재의 기본적인 물성을 변화시키지 않으면서 자외선을 차단하는 것으로 나타났다. 결론: 본 연구를 통해 trimethylsilyl methacrylate와 titanium silicon oxide는 콘택트렌즈의 기본적인 물성을 만족시키면서 고산소투과성 및 자외선 차단 콘택트렌즈 재료로 다양하게 활용될 수 있을 것으로 판단된다.

주요 수출버섯인 큰느타리버섯의 신선도유지에 적합한 포장량 및 포장재 산소투과도를 설정하기 위해저온 저장기간 중 품질변화를 분석한 결과, 포장량및 포장재 산소투과도에 따른 저장기간 중 중량감모율 변화는 차이없었으며, 갓신장율은 포장량 200g일경우 산소투과율이 높을수록 저장기간이 길수록 증가하였으나, 400g 처리는 산소투과도 3,000cc/m2,24h, atm일 때 가장 낮았다.포장재 내부의 O₂함량은 포장량이 적을수록 산소투과도가 낮을수록 높았으며, CO₂함량은 포장량이많을수록 높았다. 종합적으로 포장량 400g, 포장재산소투과도 2,000cc/m², 24h, atm 이하에서 판매가능한 신선도가 35일까지 유지되어 저장기간이 가장길었다.

The distribution of dissolved oxygen (DO) and its variability in Chunsu Bay were studied. Monthly hydrographic survey and realtime monitoring for water quality conditions were carried out in study area. Vertical distribution of DO shows the formation of hypoxia in the bottom water in the vicinity of the artificial dyke and net cage aquaculture site in summer. Annual mean of DO was 8.4 mg/l, with minimum monthly mean of 6.9 mg/l in July and maximum of 11.2 mg/l in March. Temporal variation of DO at bottom water around the net cage aquaculture site shows pronounced oscillatory characteristics with range of 0.5~7.0 mg/l. Coherency analyses between the tidal range and DO concentration shows that variation of DO is significantly coherent with tidal range at semi-diurnal period with 1~3.5 hours phase-lags. A simple DO budget model was set up to account for the formation of the extreme hypoxic conditions in Chunsu Bay. The governing equation is based on the mass-balance for kinetic process with simplified parameter of source and sink terms of DO. the source term is represented by replenishment through the vertical and horizontal diffusion and mixing. the sink terms comprise function of sediment oxygen demand (SOD) and carbonaceous biochemical oxygen demand (CBOD). The result of numerical solution indicates the dominant role of SOD as the overriding factor against the oxygen supply.

To observe the formation of defects at the interface between an oxide semiconductor and SiO2, ZnO was preparedon SiO2 with various oxygen gas flow rates by RF magnetron sputtering deposition. The crystallinity of ZnO depends on thecharacteristic of the surface of the substrate. The crystallinity of ZnO on a Si wafer increased due to the activation of ionicinteractions after an annealing process, whereas that of ZnO on SiO2 changed due to the various types of defects which hadformed as a result of the deposition conditions and the annealing process. To observe the chemical shift to understand of defectdeformations at the interface between the ZnO and SiO2, the O 1s electron spectra were convoluted into three sub-peaks bya Gaussian fitting. The O 1s electron spectra consisted of three peaks as metal oxygen (at 530.5eV), O2− ions in an oxygen-deficient region (at 531.66eV) and OH bonding (at 532.5eV). In view of the crystallinity from the peak (103) in the XRDpattern, the metal oxygen increased with a decrease in the crystallinity. However, the low FWHM (full width at half maximum)at the (103) plane caused by the high crystallinity depended on the increment of the oxygen vacancies at 531.66eV due tothe generation of O2− ions in the oxygen-deficient region formed by thermal activation energy.

본 연구는 멍게 대량폐사의 주요 현상으로 나타나고 있는 물렁증 발생의 원인을 찾기 위하여 저산소의 영향에 의한 물렁증 발생, 생존률, 대사율 및 병리조직학적 변화를 분석하였다. 용존산소의 감소에 따른 멍게의 생존률은 용존산소 농도 2 mg L-1에서 노출 4일째 모두 폐사하였으며, 3 mg L-1에서는 노출 5일째 50%를 나타내어 5days-LC50은 3.55 mg L-1 (1.86~4.96 mg L-1)로 나타났다. 그러나 저산소에 노출된 기간 동안 물렁증 발생은 관찰되지 않았다. 산소소비율은 대조구와 비교하여 용존산소 농도 5 mg L-1 이하에서 유의하게 감소하여 저산소에 노출되면 일정기간 호흡률을 조절하는 것으로 추정된다. 저산소에 의한 멍게의 새낭, 소화선 및 피낭의 병리조직학적인 변화는 각 기관을 구성하고 있는 상피세포층의 괴사, 혈구세포의 침윤, 세포핵 응축 및 변형 등이 관찰되었다. 형태적인 변화는 피낭이 쪼글어들어 부피가 작아지고 내부 기관은 탈색되고 아가미와 간췌장의 괴사가 관찰되었다.

Yellow clay dispersion has been applied to minimize fisheries impact by the red tide Cochlodinium polykrikoides blooms in Korean coasts since 1995. The present preliminary study documents the effect of yellow clay on Korean rockfish, Sebastes schlegelii, in terms of oxygen consumption rate (OCR). The OCR in the low clay suspension (0.05 and 0.23 %, w/w) showed normal level compared to the control. In contrast, the OCR for each one of three replicates in the high clay suspension (1.16 and 5.58 %, w/w) was not returned to the previous level that clay was not treated, indicating that high clay suspension (≥1.16%, w/w) might give negative effect on Korean rockfish. Overall, this result suggests that field application of clay to control Harmful Algal Blooms (HABs) may not give impact on Korean rockfish once the clay is dispersed in a low concentration (≤0.23%). In order to understand the changes of OCR in the repeated exposure to clay, it is required to do further studies on the changes of OCR when the fish is exposed to clay repeatedly after recovery in the normal seawater.

This paper is concerned with formulating the design specification and making hyperbaric oxygen chamber for multi-users. HBOT(Hyperbaric Oxygen Therapy) is very effective remedy for increasing the concentration of melted oxygen in human and animal body. The melted oxygen supplies to each cell in body to recover the normal condition. This research reported the design specifications and mechanical test results of hyperbaric oxygen chamber made with polyurethane as well as computational analysis with CATIA program. These data can set the physical dimensions of practical HBOT equipment for multi-users and be used to produce the effective commercial model.

EVA의 기체 분리 성질에 미치는 LDH의 영향을 알아보았다. Mg-Al LDH/EVA 나노복합막은 유기적으로 수정된 DS-LDH를 이용하여 용액 삽입법으로 제조되었다. DS-LDH는 LDH 층간에 DS 음이온을 삽입하여 제조하였다. 나노복합막 의 구조는 XRD, FT-IR, SEM으로 알아보았다. DS-LDH가 EVA 내에 무질서하게 분산되었음을 XRD로부터 확인하였다. LDH가 3 wt% 첨가된 나노복합막에서 인장강도와 파단신율 모두 최댓값을 나타내었다. 열적 안정도 역시 EVA에 LDH가 첨가되면서 향상되었다. 1, 3, 5 wt%의 LDH를 함유한 LDH/EVA 나노복합막의 기체투과도는 O2와 CO2에 대하여 측정하 였다. 3 wt% LDH를 함유한 경우 나노복합막의 O2에 대한 투과도가 EVA막에서보다 53% 감소하였다. 하지만 CO2 투과도는 나노복합막의 기체 차단 특성에도 불구하고 LDH 내의 OH기와 CO2 간의 높은 친화력으로 인하여 기체투과도는 증가하였다.