• Korean Journal of Agricultural Science
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• v.40 no.3
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• pp.243-252
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• 2013

This study was carried out to investigate safety evaluation of agricultural reservoirs due to raising the embankment. The seepage analysis and large-scale model test were performed to compare and analyze the pore water pressure(PWP), leakage quantity, settlement and piping phenomenon in the inclined core type and the vertical core type embankments. The PWP after raising the embankment showed smaller than before raising the embankment and the stability for piping after raising the embankment. The allowable seepage quantity and the allowable leakage for the steady state and transient conditions is within the range of safe management standard. After raising the embankment in the inclined core, there was no infiltration by leakage. For the vertical core, the PWP showed a large change by faster infiltration of pore water than in the inclined core. In a rapid drawdown, inclined core was remained stable but the vertical core showed a large change in PWP. Settlement after raising the embankment showed larger amounts of settlement than before raising the embankment. The leakage quantity before raising the embankment and the inclined core type showed no leakage. From the result, an instrument system that can accurately estimate a change of PWP shall be established for the rational maintenance and stabilization of raising the embankment for agricultural reservoirs.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.10
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• pp.24-35
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• 2017

This paper reports the results of afield appliance study of the hydraulic well method to prevent embankment seepage, the large-scale embankment experiment and seepage analysis to examine the traits of the seepage pressure. The experimental procedure was focused on the pore pressure after examining the detected value of the pore pressure gage. The inner water levels of hydraulic well were compared with the pore pressure data, which were used to inspect the seepage variations. Two different large-scale experiments were conducted according to the installation points of the hydraulic wells. The decrease in seepage pressure reached a maximum of 37% from the experimental results. The experimental pore pressure results were similar to those of the analyses. In addition, the pore pressure oriented from the water level variations of the hydraulic well showed similar patterns between the experiment and analysis, but if the hydraulic well was deeper, the analyzed water levels were larger than the experimental values.

• Fire Science and Engineering
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• v.24 no.2
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• pp.97-105
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• 2010

The smoke control systems using pressure differentials are already well known as the most reliable method to prevent the smoke infiltration into the emergency stairs or safe spaces. However, it is true that many problems are domestically pointed out due to the insufficient understanding and technology on the smoke control systems using pressure differentials. In this regard, this work analyzed the effect of major factors for smoke control system using pressure differentials such as a duct area, opening area of air supply damper, improvement on open vestibules, stack effect and location of air supply. In conclusion, adequate pressure differentials can not be maintained in small duct because the smaller duct area have the large friction loss. Especially, It is confirmed that the major factor for deterioration of smoke control system performance is stack effect that makes pressure differentials smaller in the lower floors.

• Journal of the Korean Geotechnical Society
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• v.28 no.9
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• pp.23-30
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• 2012

This paper is research results of slope stability analysis associated with seepage infiltration for unsaturated soil in debris-flow occurrence slopes. Site investigations were carried out in two slopes, located at Inje in Kangwon province where debris flow occurred in 2006 and at Yangpyung in Kyeunggi province where it occurred in 2010. For unsaturated soil sampled at the zone of debris-flow initiation, soil water characteristic curves with tempe pressure cells and shear strength parameters with newly designed shear strength apparatus were obtained respectively. The commertially available software SEEP/W was used to analyze seepage infiltration in unsaturated soil, based on their properties obtained from test results and the actual rainfall data at the moment of debris flow occurrence, and slope stability analysis with the program of SLOPE/W, associated with results of seepage analysis, was performed to simulate slope failure. As results of this research, seepage infiltration to unsaturated soil due to intensive rainfall was found to cause increase of ground water table as well as degree of saturation. Through this research slope stability analysis for unsaturated soil, considering the actual rainfall characteristic, might be a reasonable method of investigating characteristics of debris flow behavior, in particular, the moment of debris flow occurrence.

• Land and Housing Review
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• v.1 no.1
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• pp.59-65
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• 2010

The paper presents a comparison between a semi-implicit time integration linear finite element implementation and fully-implicit nonlinear Newton-Raphson finite element implementation of a triphasic small strain mixture formulation of an elastic partially saturated porous medium. The pore air phase pressure pa is assumed atmospheric, i.e., $p_a$ = 0, although the formulation and implementation are general to handle increase in pore air pressure as a result of loading, if needed. The solid skeleton phase is assumed linear isotropic elastic and partially saturated 'consolidation' in the presence of surface infiltration and traction is simulated. The verification of the implementation against an analytical solution for partially saturated pore water flow (no deformation) and comparison between the two implementations is presented and the important of the porosity-dependent nature of the partially saturated permeability is assessed on comparison with a commercial code for the partially saturated flow with deformation. As a result, the response of partially saturated permeability subjected to the porosity influences on the saturation of a soil, and the different behaviors of the partially saturated soil between staggered and monolithic coupled programs is worth of attention because the negative pore water pressure in the partially saturated soil depends on the difference.

• Journal of the Korea institute for structural maintenance and inspection
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• v.4 no.1
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• pp.101-110
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• 2000

In case heavy rainfall is a key factor of slope failure, the failure zone is usually developed within the depth of 3~5m from the ground surface regardless of the location of the watertable. If rainfall is taken into consideration, it is general that the slope stability analysis is carried out under the assumption that the cut slope is saturated to the slope surface or the watertable elevates to a certain height so that ${\gamma}_{sat}$, the unit weight of saturated soil, is used. However, the analysis method mentioned above can't exactly simulate the variation of pore water pressure in the slope and yields different failure shape. The applicability of slope stability analysis method considering the distribution of pore water pressure within the slope with heavy rainfalls, was checked out after the stability analysis of a lage-scale cut slope in a highway construction site, where surface failure occurred with heavy rainfalls. An appropriate slope stabilization method is proposed on the base of the outcome of the analysis.

• Journal of Korean Academy of Nursing
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• v.36 no.3
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• pp.523-531
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• 2006

Purpose: The purpose of this study was to examine the effects of the ulmus root-bark dressing on tissue regeneration in experimentally-induced pressure ulcers in rats. Method: A randomized pretest/post-test control group time-series study design was used. Thirty-three male Sprague-Dawley rats were used in this study. The rats were anesthetized with 100mg/kg of ketamine. Pressure ulcers were induced at 140mmHg for three hours using a personally-designed pressing apparatus. For four weeks, the ulmus root-bark dressing was applied every other day in the experimental group (n=18) and a wet gauze dressing in the control group (n=15). For data analysis, the statistical program SPSS WIN 12 was used. The wounds were examined by light microscopy andelectron microscopy. Result: There were significant statistical differences in the size of the pressure ulcers as time went by(p=0.006). It should be noted that there were no significant statistical differences in the number of capillaries. Using light microscopy the inflammatory infiltration and neovascularization in the dermis in the experimental group emerged densely in the early stages, but recovered rapidly at the latter stages. In addition, the reepithelization of the epidermis occurred earlier than in the control group. By electron microscopy, the cell organelles of the capillary endothelial cells and the basal lamina of capillaries in the experimental group showed a more rapid maturation during the latter stages, compared with the control group. Conclusion: According to this study, it can be concluded that the ulmus root-bark dressing is effective regarding the healing of pressure ulcers.

• Journal of the Korean Geotechnical Society
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• v.23 no.6
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• pp.77-84
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• 2007

One of the most sensitive design specifications to be considered is infiltration and external pore-water pressures on underground structure construction. Development of pore-water pressure may accelerate leakage and consequently cause deterioration of the lining. In this paper, the development of pore-water pressure due to malfunctioning of drainage system and its potential effect on the linings are investigated using physical model tests. The deterioration procedure was simulated by controlling both permeability and flow rate. Development of pore-water pressure was monitored on the lining using pore pressure measurement cells. Test results identified the mechanism of pore-water pressure development on the tunnel lining. In addition, they showed that controlling flow rate is more effective method fur simulating deterioration procedure than permeability control. The laboratory model tests were reproduced using coupled numerical method, and showed that the effect of deterioration of drainage system can be theoretically expected using coupled numerical modeling method.

• Journal of Dental Anesthesia and Pain Medicine
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• v.20 no.4
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• pp.203-212
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• 2020

Background: This research evaluated the numbness produced by lignocaine at an equal or higher concentration than that of 4% articaine through a single point of injection for maxillary third molar surgery. This randomized double-blind study was conducted to compare the anesthetic efficiency of 4% lignocaine with that of 4% articaine in impacted maxillary third molar surgery using a single buccal infiltration alone. Methods: The study participants were 30 healthy patients requiring the bilateral surgical removal of symmetrically-positioned maxillary third molars. Using a split-mouth design, each patient randomly received buccal infiltration of 1.7 ml of 4% lignocaine and 1.7 ml of 4% articaine during two separate appointments. After 15 minutes of anesthetic injection, surgery was performed by the same surgeon using a consistent technique on both sides. Pinprick test pain scores of the buccal and palatal gingiva of the maxillary third molar after 10 minutes and 15 minutes latencies, pain scores during the surgery, the need for supplemental anesthesia, and patients' satisfaction with anesthetic efficiency were recorded. Surgery performed without supplemental anesthesia was categorized as successful. Results: The success rates of 4% lignocaine and 4% articaine (83.34% vs. 86.67%, P = 1.00) were not significantly different. Only 5 cases (4 cases in the articaine group and 1 case in the lignocaine group) reported mild pain and pressure sensation (NRS ≤ 1) on probing at the palatal side after 15 minutes of latency (P = 0.25). The pain scores of maxillary third molar surgery in the two groups were not significantly different (P > 0.05). Moreover, the statistical analysis confirmed the comparable patient satisfaction of two study groups (P = 0.284). Conclusion: This study provides evidence that single buccal infiltrations of 4% lignocaine and 4% articaine have comparable anesthetic efficacy and success rates for impacted maxillary third molar surgery. Both 4% lignocaine and 4% articaine can produce effective palatal anesthesia and pain control using buccal infiltration alone after 15 minutes of latency.

• Journal of the Korean Ceramic Society
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• v.41 no.7
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• pp.518-527
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• 2004

In this study, SiC whiskers were grown in porous alumina substrate in order to enhance the filtering efficiency, performance, and durability by controlling pore morphology. This experiment was performed by Chemical Vapor Infiltration (CVI) in order to obtain the whiskers on the inside of pores as well as on the surface of porous the A1$_2$O$_3$ substrate. The deposition behavior was changed remarkably with the deposition position, temperature, and input gas ratio. First, the mean diameter of whisker was decreased as the position of observation moved into the inside of substrate due to the reactant gas depletion effect'. Second, the deposition temperature caused the changes of the deposition type such as debris, whiskers and films and the change in morphology affect the various properties. When SiC films were deposited. the gas permeability and the specific surface area decreased. However, the whisker showed the opposite result. The whiskers increase not only the specific surface area and minimizing pressure drop but also mechanical strength. Therefore it is expected that the porous alumina body which deposited the SiC whisker is the promising material for the filter trapping the particles.