• Title/Summary/Keyword: Pressure difference

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A Study on the Color Stability of Temporary Resins according to Polymerizing Methods and Staining (온성 방법에 따른 수종의 임시 수복용 레진의 착색시의 색 안정성에 관한 연구)

  • Park, Sung-Ho;Cho, In-Ho
    • Journal of Dental Rehabilitation and Applied Science
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    • v.16 no.1
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    • pp.1-11
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    • 2000
  • Dental temporary resin should have adequate strength and similar esthetics as natural teeth. Recently esthetics has become a high priority in clinical dentistry. Thus the evaluation of color stability of dental temporary resin has become an important part in dental research. The purpose of this study was to evaluate the difference in color stability of 3 resins($Snap^{(R)}$, Temporary bridge $resin^{(R)}$, Trim $II^{(R)}$) according to polymerizing methods and stainning. The resins were divided into groups by 2 types of polymerizing methods ( air or pressure and heat curing) The resins were dyed with coffee, chlorhexidine and artificial saliva and then the color stability was evaluated with a spectrophotometer(CM-503i, Minolta, Japan). The results were as follows ; 1. In the color stability according to polymerizing method, pressure and heat polymerizing method was higher than air polymerizing method. 2. The color stability according to staining fluid decreased in the order of I, II, III group, there was significant difference among the groups of staining fluid. 3. The color stability according to resins decreased in the order of $Snap^{(R)}$, Trim $II^{(R)}$, Temporary Bridge $resin^{(R)}$, The $Snap^{(R)}$ resin was highest color stability, there was significant difference among the 3 resins.

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Efficiency measuring in pump using Thermodynamic method (열역학법에 의한 펌프의 수력효율측정)

  • Kwon, Young June;Seo, Chang Deok;Jung, Yong Chea;Park, Jang Won
    • 유체기계공업학회:학술대회논문집
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    • 2004.12a
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    • pp.546-551
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    • 2004
  • An applying Thermodynamic method for the purpose of measuring hydraulic efficiency of pump-motor system, based on IEC60041 code, is not easy to adopt at field test. Even though there were splendid development in measuring technic in discharge measuring through the hydraulic machina lots of unsolved problems concerned in flow-rate are still remain in measuring hydraulic efficiency in hydraulic machine. The key point in measuring hydraulic efficiency is to measure exact flow-rate. So, Thermodynamic methode provides a good solution. This methode measures hydraulic efficiency by detecting the difference of temperature and pressure between the hydraulic process of machine, without measuring flow-rate of pump or turbine. By measuring temperature in mk level and absolute pressure in pascal, we can get a difference of thermodynamic specific energy in Moliere chart before and after of hydraulic process, md that difference is equal to hydraulic loses. Following the standard in proceeding Thermodynamic methode, I hope these trial and records make others be familiar to the thermal methode and make it easer to beginner for trial.

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Comparative Water Relations of Two Vitis vinifera Cultivars, Riesling and Chardonnay

  • Park, Yong-Mok
    • The Korean Journal of Ecology
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    • v.24 no.4
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    • pp.223-226
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    • 2001
  • The leaf water relations and photosynthetic rate during acute soil drying were compared in potgrown grapevine cultivars, Vitis vinifera cv. Chardonnay and V. vinifera cv. Riesling. Leaf water potential in Riesling decreased significantly from day 2 after water had been withheld, while in Chardonnay leaf water potential for the water-stressed plants was almost identical with that in well watered plants during the first 4 days. Higher stomatal conductance and photosynthetic rate in Chardonnay than Riesling were observed until day 3 after withholding water. Photosynthetic rate in water-stressed Chardonnay was not different from that in control plants until day 3 after withholding water, while that in water-stressed Riesling was reduced markedly from day 2. In Riesling, osmotic potential at turgor loss point was not changed irrespective of watering conditions. However, in Chardonnay osmotic potential at turgor loss point decreased more in the water stressed conditions than in well watered conditions. The osmotic adjustment in Chardonnay under water stress conditions must contribute to the maintenance of higher stomatal conductance and photosynthetic rate than those in Riesling for a significant period of the drying process. Though difference in stomatal conductance between the two cultivars was shown in the process of soil drying, stomatal conductance of both cultivars responded to vapor pressure difference between leaf and ambient air, rather than soil water status and leaf water potential.

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Weight-bearing on Paretic in Patients with Acute Stroke (급성 뇌졸중환자의 마비측 체중지지 임상양상)

  • Seo, Kyung-Chul;Song, Kyo-Hyun;Lee, Jung-Soo;Jang, Dan-Bi
    • Journal of Korean Physical Therapy Science
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    • v.18 no.1
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    • pp.79-84
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    • 2011
  • Background: The purpose of this study was to investigate differences in balancing ability and weight bearing between paretic and non-paretic. Methods: Subjects of the study were consisted of 30 acute hemiplegia patients(paretic 15, non-paretic 15) who were receiving rehabilitation therapy in hospital. Weight shifting was quantitatively evaluated to determine the ability of patients to and during conscious weight shifting on the Gaitview. Independent t-test was utilized to detect the mean difference between the groups. Results: 15 patients with stroke were able to shift more weight onto the paretic leg. And pressure ratio of right hemiplegia was significantly difference on the nonparetic leg, pressure ratio of left hemiplegia was significantly difference onto the paretic leg. Conclusions: Patients with left hemiplegia who was cortical lesions in the right hemisphere were able to shift more body weight onto their paretic leg. These patients should be encouraged to practice shifting their weight towards their non-paretic leg to improve their balance.

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Preliminary Study for the Development of Optimum Fuel Contact Conductance Model (최적 핵연료 접촉 열전도도 모델 개발을 위한 예비 연구)

  • Yang, Yong-Sik;Shin, Chang-Hwan
    • Proceedings of the KSME Conference
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    • 2007.05b
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    • pp.2488-2493
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    • 2007
  • A gap conductance is very important factor which can affect nuclear fuel temperature. Especially, in case of an annular fuel, a gap conductance effect can lead an unexpected heat split phenomena which is caused by a large difference of an inner and outer gap conductance. The gap conductance mechanism is very complicated behavior due to the its strong dependency on microscopic factors such as a contact surface roughness, local contact pressure and local temperature. In this paper, for the decision of test temperature and pressure range, a procedure and calculation results of in-reactor fuel temperature and pressure analysis are summarized which can be applied to test equipment design and determination of test matrix. Based upon analysis results, it is concluded that the minimum and maximum test temperature are $300^{\circ}C$ and $530^{\circ}C$ respectively, and the maximum pellet/cladding interfacial contact pressure should be observed up to 45MPa.

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Analysis of Discrete Noise Characteristics for the Cross Flow Fan with Uniform/Random hitch Blades (횡류홴 등/부등피치 블레이드의 이산소음 특성 분석)

  • Cho Yong;Kim Jong-Jin;Moon Young J.
    • 한국전산유체공학회:학술대회논문집
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    • 2000.10a
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    • pp.141-148
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    • 2000
  • The discrete noise of the cross-flow fan with uniform/random pitch blades is predicted by computational methods. With the time dependent surface pressure data obtained by solving the Wavier-Stokes equation, the acoustic pressure is calculated by the Ffowcs Williams-Hawkings equation. The positions of the blade noise source are identified through investigation of the acoustic pressure history induced by one blade, and it is confirmed that the dominant noise source is near the stabilizer. Since the acoustic pressure of the random pitch fan fluctuates according to blade passing, the dominant BPF noise for the uniform pitch fan is modified into some reduced discrete noises which have a 50Hz difference from BPF.

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A Study on Heat Transfer and Pressure drop Characteristics in Plate Heat Exchange (판형 열교환기의 열전달 및 압력강하 특성에 관한 연구)

  • 서무교;박재홍;김영수
    • Journal of Advanced Marine Engineering and Technology
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    • v.25 no.3
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    • pp.581-587
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    • 2001
  • Plate heat exchange(PHE) will be applied to the refrigeration and air conditioning systems as evaporators or condensers for their high efficiency and compactness. The purpose of this study is the analyze the characteristics of heat transfer and pressure drop of plate heat exchanger. Numerical work was conducted using the FLUENT code k-$\varepsilon$model. Also the dependence of heat transfer coefficient and friction factor on Reynolds number was investigated. As the Reynolds number increases, it is found that heat transfer coefficient also increases, but friction factor decreases. The study examines the internal flow, thermal distribution and the pressure distribution in the channel of plate heat exchanger. The results of CFD analysis compared with experimental data, and the difference of friction factor and Nusselt number in plate heat exchanger are 10% and 20%, respectively, Therefore the CFD analysis model is effective for the performance prediction of plate heat exchanger.

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Pore Pressure Behavior of Normally Consolidated Deep Sea Clay (정규압밀된 심해점토의 간극수압 거동)

  • 박용원
    • Geotechnical Engineering
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    • v.6 no.4
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    • pp.65-74
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    • 1990
  • This paper presents triaxial test (CIVC and CKOUC) results on normally consolidated deep sea clay samples. Based on the test results the pore pressure-strain relations for both isotropicaly and anisotropicaly consgidated samples are expressed with hyperbolic functions of the major princpal strain. The analysis of the difference in pore pressure behavior due to the anisotropy in consolidation stress is carried out with the effective stress pathos of CIVC and CKOUC and finds a factor which correlates the pore pressure of two types of test.

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The Pressure and Degree of Filling Balance between Cavity to Cavity in Multi-Cavity Injection Mold (다수 캐비티 금형에서 캐비티 간의 압력과 균형충전도)

  • Noh, Byeong-Su;Park, Tae-Won;Jeong, Yeong-Deug
    • Design & Manufacturing
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    • v.2 no.6
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    • pp.33-37
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    • 2008
  • Almost all injection molds have multi-cavity, which are designed with geometrically balanced runner system in order to made filling balance between cavity to cavity during injection molding. However, filling imbalance has been existed in the geometrically balanced runner system. In this study, we made an experiment and investigated that are filling balanced according to material. Also, in case of filling imbalance was occurred, we conducted experiments in order to find out difference of cavity pressure with cavity pressure sensor. When filling imbalance was occurred between cavity to cavity, we investigated the filling imbalance and pressure differences by computer-aided engineering(CAE).

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A Study on Turbine Control and Turbine Bypass Control during Startup of Thermal Power Plants (화력발전소 기동시 터빈 바이패스 시스템과 터빈 제어에 관한 고찰)

  • Choi, In-Kyu;Park, Doo-Yong
    • Proceedings of the KIEE Conference
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    • 2009.07a
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    • pp.1664_1665
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    • 2009
  • Many years ago, most of thermal power plants built in this country were of subcritical pressure, of medium or small size, of constant pressure operations and of drum type steam generators with circulation type boilers. But, nowadays almost all of them were of high efficiency, of supercritical pressure, of big capacity, of sliding pressure operations, and of once through type steam generator. It has such advantage as the reduction of startup duration, but it control system and operation method are very complicated. It has a big difference in operation method of turbine and boiler. The feedforward control needs to be introduced to prevent such problems as thermal shock during the transit from normal operation into bypass operation. This paper introduces the turbine control and turbine bypass control during startup of thermal power plants.

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