• The Journal of Internal Korean Medicine
• /
• v.33 no.1
• /
• pp.26-38
• /
• 2012

Objectives : The aim of this study was to investigate the effect of partial pyloric obstruction on body weight, gastric juice, gastric surface area and gastric edema in normal intact and/or vagotomized rats. Methods : Partial pyloric obstruction was performed by wrapping a non-absorbable rubber ring (D:6 mm, W:4 mm, T:1 mm) around the 1st portion of the duodenum. Vagotomy was performed by resecting the branches around the esophagogastric junction. Pre-post body weight differential, fasting gastric juice volume, gastric surface area and gastric edema were measured at 8 weeks and 20 weeks. For the effect of pyloric reperfusion the rubber ring was removed after 8 weeks and then an additional 12 weeks of observation was performed to the end of the 20-week experimental period. Results : In the initial 8 weeks observation, the effect of pylorus obstruction and/or vagotomy was significantly remarkable in the pylorus obstructed and vagotomized group; slowdown of weight gain, increase of fasting gastric juice volume, dilatation of gastric surface area and severe gastric edema were shown. In the remaining 12 weeks observation, the effect of reperfusion was significantly remarkable in the ring-removed antral dilated group; recovery of weight gain, decrease of gastric surface area and decrease of gastric edema were shown. However, gastric juice volume was not significantly different from the other group. Conclusions : Partial pyloric obstruction plays a aggravating role and the vagus nerve plays a protective role in body weight, gastric juice, gastric surface area, and gastric edema. Furthermore, pyloric valve dysfunction as an aggravating factor strengthened in defect of the vagus nerve. These results suggest that patients with both functional pyloric outlet obstruction and hypofunction of vagus nerve need to be diagnosed in good time and treated properly.

• Applied Biological Chemistry
• /
• v.31 no.1
• /
• pp.86-91
• /
• 1988

Natural zeolite rock of which dominent clay minerals were mordenite and clinoptilolite was collected from Wolsung, Kyungpook province. It was pulverized and sieved into four fractions of $1{\sim}0.5,\;0,5{\sim}0.25,\;0.25{\sim}0.1,$ and<0.1mm. The specific surface areas of its four fractions were determined by $H_2O$ and EGME. The specific surface area of zeolite was slightly affected according to species of measuring material, but was scarcely affected by partical size, nor increased of pulverizing. The surface area of zeolite was calculated from geometric structure of mordenite and it was compared with the specific surface area calculated from maximum numbers of $H_2O$ which could be adsorbed on mordenite. On the basis of that result, the specific area measured from zeolite was estimated to be a part of surface area calculated from it. Accordingly, it was suggested that a new method should be developed for the determination of an exact surface area of zeolite.

• Corrosion Science and Technology
• /
• v.9 no.5
• /
• pp.196-200
• /
• 2010

Recently porous metal has been used as supporting metal in planar type SOFC. In order to search optimum alloys for porous metal support and estimate the stability of metal-supported SOFC at high temperature, it is necessary to investigate the oxidation behaviors of porous material for metal support in comparison with dense material. Oxidation tests of porous and dense stainless steels were conducted at $600^{\circ}C$ and $800^{\circ}C$. Since the specific surface area of porous material is much larger than that of dense material, surface area should be considered in order to compare the oxidation rate of porous stainless steel with that of dense stainless steel. The specific surface area of porous body was measured using image analyzer. The weight gain of porous stainless steel was much greater than those of dense stainless steels due to its larger specific surface area. considering the specific surface area, the oxidation rate of porous stainless steel is likely to be the same as that of dense stainless steel with the same surface area. The change in chromium content in stainless steel during oxidation was also investigated. The experimental result in chromium content in stainless steel during oxidation corresponded with the calculated value. While the change in chromium content in dense stainless steel during oxidation is negligible, chromium content in porous stainless steel rapidly decreases with oxidation time due to its large specific surface area. The significant decrease in chromium content in porous stainless steel during oxidation may affect the oxidation resistance of porous stainless steel support and long term stability of metal-supported SOFC.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2017.05a
• /
• pp.151.1-151.1
• /
• 2017

This work studied the corrosion behavior of AZ31 Mg alloy galvanically coupled with Cu during immersion in 0.1 and 0.5 M NaCl solutions by in-situ observation and galvanic corrosion current measurement using a zero resistance ammeter. The corrosion behavior of AZ31 Mg alloy was also studied by salt spray test. The average galvanic corrosion density during 2 h immersion in 0.1 NaCl solution was found to decrease as an exponential function with increasing the surface area ratios between AZ31:Cu or with increasing the distance between AZ31 and Cu. The corrosion of electrodeposited Cu on AZ31 Mg alloy was concentrated at the area next to Cu (about 5 mm for immersion test and 2 mm for salt spray test) and pitting corrosion was accelerated at the area beyond the severely corroded area by the galvanic coupling effect.

• Journal of the korean society of oceanography
• /
• v.37 no.3
• /
• pp.187-195
• /
• 2002

The characteristics of surface circulation in the Yellow Sea and the East China Sea are discussed by analyzing a great deal of current data observed by 142 sets of mooring buoy and 58 sets of drifters trajectories collected in the Yellow Sea and the East China Sea through domestic and abroad measurements. Some major features are demonstrated as bellow: 1) Tsushima Warm Current flows away from the Kuroshio and has multiple sources in warm half year and comes only from Kuroshio surface water in cold half year. 2) Taiwan Warm Current comes mainly from the Taiwan Strait Water in warm half year and comes from the intruded Kuroshio surface water and branches near 27N in cold half year. 3) The Changjiang Diluted Water turns towards Cheju Island in summer and flows southward along the coastal line in winter. 4) The study sea area is an eddy developing area, especially in the southern area of Cheju Island and northern area of Taiwan.

• Elastomers and Composites
• /
• v.51 no.2
• /
• pp.128-137
• /
• 2016

The effect of the surface area of silicas on their reinforcing performance to styrene-butadiene rubber (SBR) compounds was systematically investigated. The feasibility of the Brunauer-Emmett-Teller surface area ($S_{BET}$) as a parameter representing the characteristics of the silicas was discussed compared to the mesopore volume, c value, oil absorption, and uptake of silane. The increase in $S_{BET}$ of silicas caused a considerable increase in Mooney viscosity, minimum torque, and hysteresis loss of the silica-filled SBR compounds, while significantly enhancing their abrasion property. These changes were explained by the attrition between the hydrophilic silica surface and the hydrophobic rubber chains. As expected, the change in $S_{BET}$ did not induce any remarkable changes in the cure, processing, tensile, and dynamic properties of the silica-filled SBR compounds because the crosslinking density of the rubber chains mainly determined these properties.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 2001.06a
• /
• pp.374-381
• /
• 2001

Surface roughness plays a significant role in friction, wear, and lubrication in machine components. Most engineering surfaces have tile nogaussian height distrubution. So, in this study, elastic-plastic contact simulations are conducted for not only gaussian surfaces but also nongaussian surfaces. Nongaussian rough surface considering the kurtosis is generated numerically. The contact simulation model takes into account the plastic deformation behaviors of asperities by setting a celing on their contact pressure at material hardness value. It will be shown that the performace variables such as real contact area fraction, plastic area fraction and average gap are sensitive to the characteristics of surface geometry according to kurtosis.

• Journal of the Korean Society for Precision Engineering
• /
• v.17 no.1
• /
• pp.27-33
• /
• 2000

This paper presents a method for determining machining parameters in 3-dimentional electrical discharge machining(EDM). The parameters are the peak value of currents, the pulse-on time, and the pulse-off time. It is known that they influence the performance of EDM more than the other else. The parameters are determined from the discharge area between a tool electrode and a work piece. The discharge area is directly influenced by the geometry of a tool surface and the tool discharge position. The discharge area on a tool discharge position is calculated from intersection curves between the tool surface and a horizontal plane. The grid search method is applied to determine the intersection curves. An example is introduced to show that the machining parameters are obtained from the surface geometry of a tool electrode.

• Structural Engineering and Mechanics
• /
• v.84 no.4
• /
• pp.561-573
• /
• 2022

This paper presents a new model to obtain the minimum area of the contact surface for rectangular isolated footings, considering that the contact surface works partially to compression (a part of the contact surface of the footing is subjected to compression and the other is not in compression or tension). The methodology is developed by integration to obtain the axial load "P", moment around the X axis "M_x" and moment around the Y axis "M_y". This document presents the simplified and precise equations of the four possible cases of footing subjected to uniaxial bending and five possible cases of footing subjected to biaxial bending. The current model considers the contact area of the footing that works totally in compression, and other models consider the contact area that works partially under compression and these are developed by very complex iterative processes. Numerical examples are presented to obtain the minimum area of rectangular footings under an axial load and moments in two directions, and the results are compared with those of other authors. The results show that the new model presents smaller areas than the other authors presented.

• Journal of the Korean Association of Geographic Information Studies
• /
• v.18 no.2
• /
• pp.59-74
• /
• 2015

The purpose of this study is to analyze reasonable green area ratios for mitigating urban heat island considering various land use types. Land uses of 5 types such as single residential, multi residential, commercial area, public facility, and industrial area were considered. Green areas were extracted from the tree attribution of land cover. Effect of urban heat island was analysed by the surface temperature of ASTER thermal infrared radiance scanned daytime and nighttime. Mitigation effect of green area at daytime was higher than nighttime. Surface temperature of green area was low in single residential at daytime. But the difference of surface temperature by each land use type was small. The effect of surface temperature mitigation of green area was lower in industrial area. The results of reasonable green area ratios for mitigating urban heat island indicate that surface temperature was the lowest with green area ratio of 40~50% in single residential, multi residential, and commercial area at daytime. Surface temperature of nighttime was not changed much by green area ratios. Therefore, the results of this study will be suggested in urban development planning to construct effectively green area for mitigating urban heat island.