• 한국미생물·생명공학회지
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• 제22권5호
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• pp.538-543
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• 1994

Effect of partial oxygen pressure on the cell growth and the activities of oxidative defense enzymes were measured in the continuous culture of Streptomyces coelicolor. Both the wild type and the mutant strain resistant to hydrogen peroxide were cultured and the dry cell weight of the two cultures were measured at different oxygen tensions. Growth of the wild type was inhibited by oxygen at above 0.5 vvm. Growth of the hydrogen peroxide resistant mutant was stimulated by pure oxygen at 0.5 vvm but was inhibited by oxygen at 1.0 vvm. Therefore, growth of the hydrogen peroxide resistant mutant was less affected by the deleterious oxidative stress of oxygen. Activities of the several defense enzymes were also measured at different oxygen tensions. Activities of catalase and glucose-6-phosphate dehydrogenase increased significantly as oxygen pressure increased in the wild type culture. In the mutant, however, increase in those enzyme activities was not obvious whereas the uninduced levels of the above enzymes were higher than those of wild type. As judged by Western blotting, the amount of the major catalase increased as the oxygen pressure increased. This indicates that the induction of the catalase activity by oxygen pressure is mostly due to the increase in the expression level for the major catalase.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2003년도 International Meeting on Information Display
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• pp.91-94
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• 2003

We studied the effect of barrier rib height variation using ray-optics code incorporated with three-dimensional plasma simulation to analyze the effects of cell geometry for varying pressure conditions. The optimal barrier rib height decreased as the Xe partial pressure increased which resulted in due to the formation of local, strong sheath under high Xe partial pressure condition.

• 소성∙가공
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• 제8권5호
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• pp.491-497
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• 1999

The effect of partial squeeze on the quality of casting products in the vacuum die casting was investigated to make defect free casting products with excellent mechanical properties. The partial squeeze and vacuum die casting process was industrially implemented in making reaction shaft support which was made of a hypereutectic Al-15%Si alloy. To combine squeezing and vacuum effects, the plunger injection system was designed and attached on the chill vent type vacuum machinery system. The combination of vacuum effect before injection and partial squeezing effect after injection resulted in defect free die casting products. The uniform distribution of fine eutectic and proeutectic Si obtained from trial process also provided excellent mechanical properties.

• 플랜트 저널
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• 제4권3호
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• pp.60-65
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• 2008

Power plant industry has been developed at high-capacity, high-technology, and innovation. Steam turbine became the most useful equipment that dominate more than 50% of all the world electricity production. And developed new materials of the turbine blade and extended length of the turbine last blade brought reform in steam turbine performance upgrade. In this paper, when do partial load driving in high-capacity steam turbine, optimum driving method found whether there is something. In operating steam turbine, there is a lot of loss from secondary wake and throttle of the 1st stage nozzle by the biggest leading factor that load fluctuation affects in high-pressure steam turbine performance. Effect of internal efficiency by 1 stage nozzle is the biggest here, but here fluid flow and flow analysis were not yet examined closely definitely. So, Analyzed design data and acceptance performance test result to applying subcritical pressure drum type 560 MW, supercritical-pressure once through type 500 MW, and 800 MW steam turbines actually. In conclusion, at partial load driving, partial arc admission(PAA) is more efficient than full arc admission(FAA) efficiency. This is judged by because increase being proportional with gross energy of stream that is pressure - available energy if pressure of stream that is flowed in to the turbine increases, available energy becomes maximum and turbine efficiency improves. Therefore, turbine performance is that preview that first stage performance fell if decline is serious in partial load because first stage performance changes according to load.

• 한국안광학회지
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• 제5권2호
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• pp.193-199
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• 2000

수소화된 비정질 탄소 박막은 PECVD 방법으로 제작하였으며 박막의 증착률은 아세틸렌 가스의 함량에 의존하였다. 이것은 메탄 기체를 사용하였을 때와 비교해 조금 높았다. 박막의 광학적 밴드 갭은 1.4~1.8eV였으며 아세틸렌 함량에 밀접한 연관성을 보여주었다. Raman과 FTIR 분광에 의하여 $sp^3/sp^2$의 정성적인 분율을 결정할 수 있었으며 이러한 결과로부터 아세틸렌 함량 13.8%의 박막이 최적의 조건이었다.

• 한국전기전자재료학회논문지
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• 제16권9호
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• pp.775-782
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• 2003

In the study, the total conductivies in [(Ce $O_2$)$_{1-x}$ (Zr $O_2$)$_{x}$]$_{0.8}$(Sm $O_{1.5}$)$_{0.2}$ (x- 0, 0.05, 0.1, 0.2) solid solution were measured as a function of temperature and oxygen partial pressure between 80$0^{\circ}C$ and 1,00$0^{\circ}C$ using 4-probe d.c method. Under pure oxygen atmospere, the oxygen ionic conductivity of [(Ce $O_2$)$_{1-x}$ (Zr $O_2$)$_{x}$]$_{0.8}$(Sm $O_{1.5}$)$_{0.2}$ decreased with the concentration of Zr $O_2$At high oxygen partial pressure, the electrical conductivity is almost independent of oxygen partial pressure and decreased with the increase in Zr content. However, the electrical conductivity increase with decreasing oxygen partial pressure and is almost independent of Zr content at low oxygen partial pressure. Empirically, Total conductivity( $\sigma$ ) was expressed by the p$o_{2}$ -independent conductivity as $\sigma$$_{i}$, and the $p_{-1/4}$ $o_{2}$sup -dependent part as $\sigma$$_{e}$. Total, ionic and electronic conductivities fitted by data enabled to determine the transference number. The ionic transference number( $t_{i}$ ) decreased while the electronic transference( $t_{e}$ ) increase with the increase in Zr content and p$o_{2}$.

• 한국안전학회지
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• 제14권3호
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• pp.40-47
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• 1999

A numerical study on gaseous explosion was carried out to predict the transient pressure behavior with the partial rupture in confined vessels. Equations, assumptions and solutions for central ignition of premixed gases in closed spherical vessels are proposed with various equivalence ratios of gas fuel, as $CH_4$ and $C_3H_8$, vent areas and vent opening pressures. Given vent opening pressure in a vessel, the magnitude of second peak pressure results from the vent areas and burning velocity, varied by equivalence ratio of gas fuel. In a living room of an apartment, the higher second peak pressure than the vent pressure is not appeared due to its large window areas. As vent opening pressure is higher, the larger damage by gaseous explosion is expected and the larger vent area is necessary for relieving the damage. In the same concentration, the gaseous explosion by propane rather than methane shows the larger damage due to its higher adiabatic flame temperature and equivalence ratio.

• 대한치과기공학회지
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• 제30권2호
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• pp.47-56
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• 2008

This is a research for thickness change of denture base according to the shape of sprue & investment position of denture base in flask when injecting polyamid base resin for flexible partial denture as a part of study for Valplast among the flexible partial denture with a nylon base. It has been introduced several kinds of flexible partial denture product with a nylon base, but Valplast is the most widely used product among them. Valplast has been the most generally used material today since developed in 1950s in the United States as a material for flexible partial denture. Valplast is much more aesthetic than general metal-acrylic partial denture due to its translucent pink color and biocompatibility in terms of material characteristic. It keeps its flexibility for a long time after production, imposes a less burden on the teeth used as abutment, and it can be easily insert and remove due to its particular suppleness. Moreover, it is felt like real teeth more than metal-acrylic partial denture when being put in and takes alveolar bone under good protection since it receives occlusal force equally under the denture base. The most outstanding feature of Valplast is flexibility. The extent of its flexibility is determined by width & thickness of denture base. Considering general working procedure of Valplast, it can be seen that the thickness of denture base formed out of wax is increasing by the pressure while injecting resin. This research is to decide and test on the thickness increasing of Valplast by injecting pressure and the hypothesis upon that and is to prepare the basis estimating the increasing extent of thickness of denture base on the basis of the test result. In this test, it is expected occlusal malposition & thickness increasing of denture base by injecting pressure according to 4 kinds of test data which are to select 3 types of sprue method settling the forefront position at which the test material of fixed standard can be invested and to position the test material at the rearmost part keeping the minimum distance to set sprue. For 4 kinds of injecting test by investment position & sprue type, 20 test materials, 5 for each test were produced and a pressure of 1,180Kg was given with automatic injector of air cylinder type. The results are as follows: 1. For the amount of thickness increasing of denture base by investment position, the thickness of front investment is less increasing than the one of rear investment. 2. For the amount of thickness increasing of denture base by sprue type, the thickness of straight decompression sprue type which can absorb the injecting pressure after injecting polyamide base resin is less increasing than the other sprue types.

• 한국표면공학회지
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• 제39권6호
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• pp.250-254
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• 2006

Effect of hydrogen partial pressure ratio on the structural and electrical properties of highly c-axis oriented ZnO films deposited by oxygen ion-assisted pulsed filtered vacuum arc at a room temperature was investigated. The hydrogen partial pressure ratio were $1.4%\sim9.8%$ at 40% oxygen pressure ratio. The conductivity of ZnO:H films was increased from 1.4% up to 4.2% due to relatively high carrier mobility caused by improvement of crystallinity While the conductivity of ZnO:H films were decreased over than 4.2% and (0002) orientation was also deteriorated. The lowest resistivity of ZnO:H films was $2.5{\times}10^{-3}\;{\Omega}{\cdot}cm$ at 4.2% of hydrogen pressure ratio. Transmittance of ZnO:H films in visible range was 85% which is lower than that of undoped ZnO films because of declined preferred orientation.

• 한국재료학회지
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• 제13권3호
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• pp.150-154
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• 2003

Amorphous carbon nitride films were deposited on Si(001) substrates by a plasma enhanced chemical vapor deposition technique (PECVD) using $CH_4$and $N_2$as reaction gases. The growth and film properties were investigated while the gas ratio and the working pressure were changed systematically. At 1 Torr working pressure, an increase in the $N_2$partial pressure results in a significant increase of the deposition rate as well as an apparent presence of C ≡N bonding, while little affecting the microstructure and amorphus nature of the films. In the case of changing the working pressure at a fixed $N_2$partial pressure of 98%, a film grown at a medium pressure of $1${\times}$10^{-2}$ Torr shows the most prominent C=N bonding nature and photoluminescent property.