• Title/Summary/Keyword: Inner water pressure

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Structural Design Equation for a Box-shape Pressure Compensated Chamber of Pilot Mining Robot (파일럿 집광로봇 박스형 압력보상용기 구조설계식)

  • Lee, Minuk;Hong, Sup;Lim, Woochul;Lee, Tae Hee;Choi, Jong-Su
    • Journal of Ocean Engineering and Technology
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    • v.26 no.6
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    • pp.66-73
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    • 2012
  • A pressure compensated chamber of a pilot mining robot isolates and protects an electrical-electronic system from the ambient highly pressured water. Since the inner pressure of the chamber is compensated with outer water pressure using hydraulic oil and pressure compensator, there exists a pressure difference, less than 1 bar, between outer and inner surface. The structural safety of the chamber is obtained relatively easier than the canister type which inner pressure is kept as the atmospheric pressure. However, due to the adoption of box shape for space efficiency and usage of the transparent engineering plastic viewport for checking inner circumstance, the viewport can be largely deformed. This large deformation can cause an additional tensile force, called the prying force, to the bolt-flange connection parts of the viewport. In this paper, we suggest the structural design equation considering the prying action for designing the structure of a box-shape pressure compensated chamber.

Experimental Studies of the Explosion Characteristics by Varying Concentrations of a Multi Layered Water Gel Barrier (다층구조 Water Gel Barrier의 농도변화에 따른 폭발특성에 대한 실험적 연구)

  • Ha, Dae Il;Park, Dal Jae
    • Journal of the Korean Society of Safety
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    • v.34 no.1
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    • pp.40-44
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    • 2019
  • Experimental studies have been carried out to investigate characteristics of gas explosion using a multi layered water gel barrier in a vented explosion chamber. The chamber is consisted of 1600 mm in length, with a square cross-section of $100{\times}100mm^2$. The gel concentration of inner layer of MLWGB ranged from 10% to 90% with intervals of 10% by weight of gel. Displacement of the MLWGB was photographed with a measured using a high-speed video camera, and pressure development was measured using a data acquisition system. It was found that MLWGBs with 10 ~ 20% inner layer concentrations were ruptured during the explosions. As the concentrations of inner layer increased from 30% to 90%, the barriers were not ruptured. As the gel concentrations of the inner layer increased, the displacement increased toward the chamber exit and the pressure decreased for the ruptured barriers. It was found that the pressure attenuation obtained from the MLWGB was higher than that of the single water gel barrier. For the cases of non-ruptured barriers, the pressure inside the chamber less increased with increasing gel concentrations of the inner layer. It was also found that the displacement moved back into the chamber for non-ruptured MLWGBs, and it was sensitive to the gel concentrations.

On the Prediction of Inner Pressure for the Tank in Rolling Motion (동요하는 탱크의 내부 변동압력 추정에 관한 연구)

  • Lee, Seung-Keon;Sea, Young-seok
    • Journal of Navigation and Port Research
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    • v.27 no.5
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    • pp.459-464
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    • 2003
  • The inner liquid pressure of an airtight tank in rolling motions is investigated by means of forced oscillation tests, and the simple method to estimate the inner liquid pressure is proposed. A rectangular solid tank, which is fully filled with water, was used in the forced oscillation test of rolling motion. The inner pressure variations in time were measured at several points on the inner walls of tank. Measured pressures are compared with the calculated ones, and estimation methods of the inner liquid pressure of the tank in rolling motion are studied based on the considerations of the origin of pressure.

Influence of burial conditions on the seepage characteristics of uranium bearing loose sandstone

  • Quan Jiang;Mingtao Jia;Yihan Yang;Qi Xu;Chuanfei Zhang;Xiangxue Zhang;Meifang Chen
    • Nuclear Engineering and Technology
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    • v.56 no.4
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    • pp.1357-1371
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    • 2024
  • To investigate the influence of different burial conditions on the seepage characteristics of loose sandstone in the leaching mining of sandstone uranium ore, this study applied different ground pressures and water pressures to rock samples at different burial depths to alter the rock's seepage characteristics. The permeability, pore distribution, and particle distribution characteristic parameters were determined, and the results showed that at the same burial depth, ground pressure had a greater effect on the reduction in permeability than water pressure. The patterns and mechanisms are as follows: under the influence of ground pressure, increasing the burial depth compresses the pores in the rock samples, decreases the proportion of effective permeable pores, and causes particle fragmentation, which blocks pore channels, resulting in a decrease in permeability. Under the influence of water pressure, increasing the burial depth expands the pores but also causes hard clay particles to decompose and block pore channels. As the burial depth increases, the particles eventually decompose completely, and the permeability initially decreases and then increases. In this experiment, the relationships between permeability and the proportion of pores larger than 0.15 ㎛ and the proportion of particles smaller than 59 ㎛ were found to be the most significant.

A Study on the Transitional Flows in a Concentric Annulus with Rotating Inner Cylinder (안쪽 축이 회전하는 환형관내 천이유동에 관한 연구)

  • 김영주;황영규;우남섭
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.14 no.10
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    • pp.833-843
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    • 2002
  • The present experimental and numerical investigations are performed for the characteristics of transitional flow in a concentric annulus with a diameter ratio of 0.52, whose outer cylinder is stationary and inner one rotating. The pressure losses and skin- friction coefficients have been measured for the fully developed flow of water and glycerine-water solution (44%) with the inner cylinder rotating at speed of 0∼600 nm, respectively. The transitional flow has been examined by the measurement of pressure losses to reveal the relation of the Reynolds and Rossby numbers with the skin-friction coefficients. The occurrence of transition has been checked by the gradient changes of pressure losses and skin-friction coefficients with respect to the Reynolds numbers. The increasing rate of skin-friction coefficient due to the rotation is uniform for laminar flow regime, whereas it is suddenly reduced for transitional flow regime and, then, it is gradually declined for turbulent flow regime.

Experimental study on the helical flow field in a concentric annulus with rotating inner cylinders (안쪽축이 회전하는 환형관내 헬리컬 유동장의 실험적연구)

  • Hwang, Young-Kyu;Kim, Young-Ju
    • Proceedings of the KSME Conference
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    • 2000.04b
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    • pp.631-636
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    • 2000
  • The experimental study concerns the characteristics of a transitional flow in a concentric annulus with a diameter ration of 0.52, whose outer cylinder is stationary and inner one rotating. The pressure drops and skin-friction coefficients have been measured for the fully developed flow of water and that of glycerine-water solution (44%) at a inner cylinder rotational speed of $0{\sim}600$ rpm, respectively. The transitional flow have been examined by the measurement of pressure drops and the visualization of flow field, to reveal the relation of the Reynolds and Rossby numbers with the skin-friction coefficients and to understand the flow instability mechanism. The present results show that the skin-friction coefficients have the significant relation with the Rossby numbers, only for laminar regime. The occurrence of transition has been checked by the gradient changes of pressure drops and skin-friction coefficients with respect to the Reynolds numbers. The increasing rate of skin-friction coefficient due to the rotation is uniform for laminar flow regime, whereas it is suddenly reduced for transitional flow regime and, then, is gradually declined for turbulent flow regime. Consequently, the critical (axial-flow) Reynolds number decreases as the rotational speed increases. Thus, the rotation of inner cylinder promotes the early occurrence of transition due to the excitation of taylor vortices.

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Experimental Study on the Helical Flow Field in a Concentric Annulus with Rotating Inner Cylinders (안쪽축이 회전하는 환형관내 헬리컬 유동장의 실험적 연구)

  • Hwang, Young-Kyu;Kim, Young-Ju
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.24 no.6
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    • pp.822-833
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    • 2000
  • This experimental study concerns the characteristics of a transitional flow in a concentric annulus with a diameter ratio of 0.52, whose outer cylinder is stationary and inner one rotating. The pressure drops and skin-friction coefficients have been measured for the fully developed flow of water and that of glycerine-water solution (44%) at a inner cylinder rotational speed of $0{\sim}600$ rpm, respectively. The transitional flow has been examined by the measurement of pressure drops and the visualization of flow field, to reveal the relation of the Reynolds and Rossby numbers with the skin-friction coefficients and to understand the flow instability mechanism. The present results show that the skin-friction coefficients have the significant relation with the Rossby numbers, only for laminar regime. The occurrence of transition has been checked by the gradient changes of pressure drops and skin-friction coefficients with respect to the Reynolds numbers. The increasing rate of skin-friction coefficient due to the rotation is uniform for laminar flow regime, whereas it is suddenly reduced for transitional flow regime and, then, it is gradually declined for turbulent flow regime. Consequently, the critical (axial-flow) Reynolds number decreases as the rotational speed increases. Thus, the rotation of inner cylinder promotes the early occurrence of transition due to the excitation of taylor vortices.

Stabilization and Drug Release of Water/Oil/Water Multiple Emulsions : Effect of Glucose in the Outer Aqueous Phase on Osmotic Pressure Reduction (Water/Oil/Water 다중유화의 안정성과 약물 방출: 외부 수상에 포함된 글루코즈에 의한 삼투압 조절 효과)

  • Yoo, Youngtai;Lim, Eun-Jung;Kim, Tae-Yoon;Kim, Dong-Chul
    • Applied Chemistry for Engineering
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    • v.8 no.5
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    • pp.715-721
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    • 1997
  • W/O/W multiple emulsions were prepared comprising $MgSO_4$ in the inner aqueous phase as a model drug. The stability and drug release behavior of the multiple emulsions were studied using optical microscopy, viscometry and conductometry. Glucose was introduced in the outer aqueous phase to reduce the osmotic pressure gradient across the oil layer arising from the localization of drug molecules in the inner water phase. It was found that the presence of glucose was effective in stabilization of the multiple emulsions and in control of the release rate of drug more evidently when oil phase was partially hydrophilized with cetostearyl alcohol. This may be attributed to the fact that the migration of water accompanying the hydrophilic surfactant to the inner water phase was limited under a reduced osmotic pressure gradient and thereby slow down the destabilization of the oil/inner water interface.

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Hydro-mechanical interaction of reinforced concrete lining in hydraulic pressure tunnel

  • Wu, He-Gao;Zhou, Li;Su, Kai;Zhou, Ya-Feng;Wen, Xi-Yu
    • Structural Engineering and Mechanics
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    • v.71 no.6
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    • pp.699-712
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    • 2019
  • The reinforced concrete lining of hydraulic pressure tunnels tends to crack under high inner water pressure (IWP), which results in the inner water exosmosis along cracks and involves typical hydro-mechanical interaction. This study aims at the development, validation and application of an indirect-coupled method to simulate the lining cracking process. Based on the concrete damage plasticity (CDP) model, the utility routine GETVRM and the user subroutine USDFLD in the finite element code ABAQUS is employed to calculate and adjust the secondary hydraulic conductivity according to the material damage and the plastic volume strain. The friction-contact method (FCM) is introduced to track the lining-rock interface behavior. Compared with the traditional node-shared method (NSM) model, the FCM model is more feasible to simulate the lining cracking process. The number of cracks and the reinforcement stress can be significantly reduced, which matches well with the observed results in engineering practices. Moreover, the damage evolution of reinforced concrete lining can be effectively slowed down. This numerical method provides an insight into the cracking process of reinforced concrete lining in hydraulic pressure tunnels.

Effect of Betula schmidtii Regel on Blood Pressure (한국산 생약제들의 혈압강하작용에 대한 연구(III) -박달수피의 혈압에 대한 작용-)

  • Lee, Jong-Wha;Kim, In-Soon;Kim, Ock-Yo;Cho, Byung-Hyun;Cho, Kyu-Chul
    • Korean Journal of Pharmacognosy
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    • v.10 no.3
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    • pp.125-135
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    • 1979
  • This study was undertaken to search for a new antihypertensive or hypotensive agents in natural crude products in Korea. Betula schmidtii Regel, a tree belonging to the Betulaceae family, is cultivated for the most part of our country, and their cortecies or tree milk has been used as folk remedy, which exerted good antiinflammatory effect on rheumatic fever, arthritis or rheumatism. The rats were treated with several extracts from Betula schmidtii Regel, that is, extracts of water, methanol from inner cortecies, extracts of ether, methanol, hexane, chloroform or butanol from outer and total cortecies. In this experiment, we measured the blood pressure and heart rate in anesthetized rats, and atropine, diphenhydramine, phentolamine, propranolol, epinephrine, hexamethonium and hydralazine were pretreated prior to Betula extracts to clarify the mechanism of the hypotensive action. The results of the experiment were as follows; 1. BOIE(Betula outer cortex water-insoluble extract) and BICE(Betula inner cortex chloroform extract) elevated the blood pressure and heart rate. 2. BIME(Betula inner cortex methanol extract), BIBE(Betula inner cortex butanol extract) and BIWE (Betula inner cortex water extract) significantly lowered the blood pressure and heart rate. 3. With the pretreatment of hydralazine, the hypotensive effect of Betula schmidtii Regel was significantly blocked. From the above results, it is suggested that the hypotensive effect of Betula schmidtii Regel is due to the direct vasodilation of blood vessel.

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