• 대한약리학회지
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• 제23권2호
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• pp.113-121
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• 1987

국소마취제가 mitochondria에서의 전자이동 및 superoxide라디칼의 생성 그리고 지질의 과산화에 따른 malondialdehyde생성에 미치는 영향을 관찰하였다. 국소마취제는 전자이동계 의 효소활성도에 영향을 나타내었다. NADH dehydrogenase, NADH oxidase와 NADH-ubiquinone oxidoreductase의 활성도는 lidocaine, procaine과 dibucaine에 의하여 효과적으로 억제되었고 cocaine에 의하여 약간 억제되었다. Succinate dehydrogenase, succinate cytochrome c oxidoreductase와 succinate-ubiquinone oxidoreductase 활성도는 lidocaine 과 dibucaine에 의하여 억제되었으나 succinate oxidase는 국소마취제에 의하여 활성화되었다. 국소마취제는 dihydroubiquinone-cytochrome c oxidoreducatse와 cytochrome c oxidase의 활성도를 억제하였다. 이와 같은 반응에서 국소마취제에 대한 complex I segment의 반응이 다른 complex segment보다 크게 나타났다. 국소마취제는 succinate 또는 NADH에 의한 superoxide 생성과 이에 대한 antimycin의 자극효과를 억제하였다. 또한 국소마취제는 산소라디칼에 의한 지질의 과산화를 억제하였다. 이상의 결과로부터 국소마취제는 mitochondria의 전자전달 과정 중 Complex I segment때 또는 인접한 부위에 작용하여 전자이동을 억제함으로써 superoxide 생성과 지질의 과산화를 억제할 것으로 시사되었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.64-64
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• 2009

Atomic force microscopy (AFM) fabrication of oxide patterns is an attractive technique for nanoscale patterns and related device structures, SiC exhibits good performance in high-power, high-frequency, and high-temperature conditions that is comparable to the performance of Si. The AFM fabrication of oxide patterns on SiC is important for electronic applications. However, there has not been much reported investigations on oxidation of SiC using AFM. We achieved the local oxidation of 4H-SiC using the high loading force of ~100 nN, although the oxidation of SiC is generally difficult mainly due to the physical hardness and chemical inactivity. All the experiments were performed using atomic force microscopy (S.I.S. GmbH, Germany) with a Pt/Ir-coated Si tip at ~40% humidity and room temperature. The spring constant and resonance frequency of the tip were around ~3 N/m and ~70 kHz. We fabricated oxide patterns on n-type 4H-SiC ($\sim10^{19}/cm^3$) and n-type Si ($\sim1.9\times10^{16}/cm^3$). In summary, we demonstrated that the oxide patterns can be obtained over the electric field of ${\sim}\times10^7 V/cm$ and the high loading force using the tip as a cathode. The electric field transports the oxyanions (OH-) to the positively biased surface.

• Asian-Australasian Journal of Animal Sciences
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• 제25권6호
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• pp.824-831
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• 2012

The objective was to compare meat quality, muscle fiber characteristics, lipid oxidation and fatty acids of Limousin (LIM), Simmtental (SIM), Luxi (LX), Qinchuan (QC) and Jinnan (JN) offered the same diet in China. After finishing, eight bulls from each breed were randomly selected for slaughter at 18.5 months old. Longissimus dorsi (ld) muscle was taken from the carcass for meat quality evaluations. Breed had little effect on most of meat and fat color parameters except for Hue and $b^*$ in which QC had lower values. LIM showed higher pH (24 h) and better water holding capacity than other breeds. LIM showed the lowest dry matter content but the highest crude protein. LX and LIM had higher percentage and density of red muscle fiber than other breeds. Lipid oxidations were significantly lower in LIM than in QC, with the LX, SIM and JN having the intermediate values. Compared to other four breeds, QC provided the highest values of polyunsaturated fatty acids (PUFA), n-6 fatty acids and n-3 fatty acids. In conclusion, LIM scored better on most of meat quality characteristics; however, local breeds such as LX and QC also had better muscle fiber characteristics and better fatty acids composition.

• Molecules and Cells
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• 제39권1호
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• pp.65-71
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• 2016

A challenge in the redox field is the elucidation of the molecular mechanisms, by which $H_2O_2$ mediates signal transduction in cells. This is relevant since redox pathways are disturbed in some pathologies. The transcription factor OxyR is the $H_2O_2$ sensor in bacteria, whereas Cys-based peroxidases are involved in the perception of this oxidant in eukaryotic cells. Three possible mechanisms may be involved in $H_2O_2$ signaling that are not mutually exclusive. In the simplest pathway, $H_2O_2$ signals through direct oxidation of the signaling protein, such as a phosphatase or a transcription factor. Although signaling proteins are frequently observed in the oxidized state in biological systems, in most cases their direct oxidation by $H_2O_2$ is too slow ($10^1M^{-1}s^{-1}$ range) to outcompete Cys-based peroxidases and glutathione. In some particular cellular compartments (such as vicinity of NADPH oxidases), it is possible that a signaling protein faces extremely high $H_2O_2$ concentrations, making the direct oxidation feasible. Alternatively, high $H_2O_2$ levels can hyperoxidize peroxiredoxins leading to local building up of $H_2O_2$ that then could oxidize a signaling protein (floodgate hypothesis). In a second model, $H_2O_2$ oxidizes Cys-based peroxidases that then through thiol-disulfide reshuffling would transmit the oxidized equivalents to the signaling protein. The third model of signaling is centered on the reducing substrate of Cys-based peroxidases that in most cases is thioredoxin. Is this model, peroxiredoxins would signal by modulating the thioredoxin redox status. More kinetic data is required to allow the identification of the complex network of thiol switches.

• Tribology and Lubricants
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• 제35권2호
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• pp.99-105
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• 2019

This study presents an experimental investigation of the wear and oxidation of the bristles of a brush seal in a super-heated steam environment. We construct a model reflecting normal force and radial interference to predict the amount of wear. To monitor the volume loss of the bristle induced by the swirl phenomenon of the rotor, we measure the clearance between the rotor and the brush seal by using a non-contact 3-D device. We calculate the area by using the area-wise measurement method. Considering the obvious brush seal wear variables, we use two disks with different roughness($Ra=0.1{\mu}m$ and $100{\mu}m$) to determine the effect of roughness on wear. Considering an actual steam turbine, we utilize a steam generator and super-heater to generate a working fluid (0.95MPa, 523.15K) that has high kinetic energy. We observe the abrasion of the bristles in the hot steam environment through a scanning electron microscope image. This study also conducted energy dispersive X-ray (EDX) analysis for a qualitative evaluation of local chemistry. The results indicate that the wear and elimination of bristles occur on the disk with high roughness, and the weight increases due to oxidation. Furthermore these results, reveal that the bristle oxidation is accelerated more under super-heated steam conditions than under conditions without steam.

• 자원환경지질
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• 제47권1호
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• pp.61-69
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• 2014

중금속류나 방사성 물질로 오염된 지하수를 원위치에서 처리(정화 혹은 고정화)하고자 할 때, 반드시 고려해야 할 지화학적 요소 중의 하나는 지하수의 산화/환원전위 값이다. 우리는 생지화학적 작용에 의한 현장 지하수의 산화/환원전위 변화 특성을 알아보기 위해 실험실 조건에서 한국원자력연구원의 심부지하수를 대상으로 전자공여체(젖산), 전자수용체(황산염) 및 토착미생물을 주입하여 시간별로 산화/환원전위 변화를 관찰하였다. 질소가스-충전 글로브박스에 있는 순수 지하수는 시간이 경과함에 따라 미약한 Eh 상승(약산화)이 있었다. 하지만, 젖산, 황산염 혹은 미생물이 주입된 지하수 대부분의 Eh는 감소(환원)하는 특성을 보여주었다. 특히, 국내 토착 황산염환원미생물인 '바쿨라텀'이 주입되었을 때, 지하수의 Eh가 -500 mV 근처까지 감소하여 강환원성 지하수로 바뀌었다. 이처럼 일반 금속환원박테리아에 비해 황산염환원박테리아의 지하수 환원화 능력이 매우 우수함에도 불구하고, 용존 황산철을 필요로 하였고 최종적으로 황화광물(예; 맥키나와이트)이 생성되면서 추후 반응에 관한 예측을 어렵게 하였다. 결과적으로, 미생물 외에도 미량의 영양물질 주입 여하에 따라 지하수의 산화/환원전위가 크게 달라졌으며, 이는 산화/환원전위의 영향을 받는 용존 오염 물질의 산화수, 용해도 및 수착 등의 특성들이 생물자극법에 의해 바뀌거나 조절될 수 있음을 의미한다.

• ETRI Journal
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• 제27권5호
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• pp.569-578
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• 2005

The purpose of this paper is to describe the implementation of monolithically matching circuits, interface circuits, and RF core circuits to the same substrate. We designed and fabricated on-chip 1 to 6 GHz up-conversion and 1 to 8 GHz down-conversion mixers using a 0.8 mm SiGe hetero-junction bipolar transistor (HBT) process technology. To fabricate a SiGe HBT, we used a reduced pressure chemical vapor deposition (RPCVD) system to grow a base epitaxial layer, and we adopted local oxidation of silicon (LOCOS) isolation to separate the device terminals. An up-conversion mixer was implemented on-chip using an intermediate frequency (IF) matching circuit, local oscillator (LO)/radio frequency (RF) wideband matching circuits, LO/IF input balun circuits, and an RF output balun circuit. The measured results of the fabricated up-conversion mixer show a positive power conversion gain from 1 to 6 GHz and a bandwidth of about 4.5 GHz. Also, the down-conversion mixer was implemented on-chip using LO/RF wideband matching circuits, LO/RF input balun circuits, and an IF output balun circuit. The measured results of the fabricated down-conversion mixer show a positive power conversion gain from 1 to 8 GHz and a bandwidth of about 4.5 GHz.

• Journal of Welding and Joining
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• 제28권5호
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• pp.80-85
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• 2010

This study focused on laser assisted machining (LAM) of silicon nitride ceramic that efficiently removes the material through machining of the softened zone by local heating. The effects of laser-assisted machining parameters were studied for cost reduction, and active application in processing of silicon nitride ceramics in this study. Laser assisted machining of silicon nitride allows effective cutting using CBN tool by local heating of the cutting part to the softening temperature of YSiAlON using by the laser beam. When silicon nitride is sufficiently preheated, the surface is oxidized and decomposed and then forms bloating, micro crack and silicate layer, thereby making the cutting process more advantageous. HIPSN and SSN specimens were used to study the machining characteristics. Higher laser power makes severer oxidation and decomposition of both materials. Therefore, HIPSN and SSN specimens were machined more effectively at higher power.

• 국제학술발표논문집
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• The 5th International Conference on Construction Engineering and Project Management
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• pp.196-203
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• 2013

Environmental problems like global warming have now become important issues that should be considered in all industries, including construction. In South Korea, many studies have been conducted to achieve the government's goals of reduction in environmental impacts. However, the research on buildings has only focused on CO₂ emission as a research target despite the fact that other environmental impacts resulting from ozone depletion and acidification should also be considered, in addition to global warming. In this regard, this study attempted to propose assessment criteria and methods to evaluate the environmental performance of the structures from various aspects. The environmental impact category can be divided into global impacts, regional impacts, and local impacts. First, global impacts include global warming, ozone layer depletion, and abiotic resource depletion, while regional impacts include acidification, eutrophication, and photochemical oxidation. In addition, noise and vibration occurring in the building construction phase are defined as local impacts. The evaluation methods on the eight environmental impacts will be proposed after analyzing existing studies, and the methods representing each environmental load as monetary value will be presented. The methods presented in this study will present benefits that can be obtained through green buildings with a clear quantitative assessment on structures. Ultimately, it is expected that if the effects of green buildings are clearly presented through the findings of this study, the greening of structures will be actively expanded.

• 방사성폐기물학회지
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• 제3권4호
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• pp.301-307
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• 2005

조사후 핵연료 가열(PIA장비)를 이용한 고연소도 UO2 사용후 핵연료의 산화 및 가열후 미세조직의 변화를 관찰하였다. 울진 2호기에서 한국원자력연구소 조사후시험시설로 이송된 국산 경수로용 고연소도 사용후 핵연료는 봉평균 연소도가 57,000 MWd/tU-rod avg.이였다. 본 시험에 사용된 시편은 국부연소도 65,000 MWd/tU UO2 소결체의 고형체 200 mg을 사용하였다. 본 시편을 사용후 핵 연료 가열(PIA) 시험장비를 이용하여 핫셀 내에서 3시간의 산화시험과 연속적으로 $1,400^{\circ}C$ 까지 가열하였다. 결정립경계까지의 산화를 위하여 $500^{\circ}C$에서 헬륨 50 ml, 표준공기 100 ml를 흔합한 산화분위기로 3시간을 유지하였다. 핵분열기체 방출거동을 알기위해 시험 전과정중에 85Kr의 방출량을 베타 측정기와 감마 측정기를 이용하여 실시간으로 측정 하였다. 가열시험이 종료된 후 전자주사현미경을 이용하여 미세구조의 변화를 관찰하였다. 시험결과 가열하는 동안 핵분열생성물은 UO2기지의 결정립경계와 표면으로 이동된 것을 관찰하였다. 이 시편은 환원과정을 통하여 재구조화 되었고, $5\~10\;{\mu}m$ 정도의 결정립크기를 가진 것으로 나타났다.