• Title, Summary, Keyword: bubble-point

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Development of the Interfacial Area Concentration Measurement Method Using a Five Sensor Conductivity Probe

  • Euh, Dong-Jin;Yun, Byong-Jo;Song, Chul-Hwa;Kwon, Tae-Soon;Chung, Moon-Ki;Lee, Un-Chul
    • Nuclear Engineering and Technology
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    • v.32 no.5
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    • pp.433-445
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    • 2000
  • The interfacial area concentration (IAC) is one of the most important parameters in the two-fluid model for two-phase flow analysis. The IAC can be measured by a local conductivity probe method that uses the difference of conductivity between water and air/steam. The number of sensors in the conductivity probe may be differently chosen by considering the flow regime of two-phase flow. The four sensor conductivity probe method predicts the IAC without any assumptions of the bubble shape. The local IAC can be obtained by measuring the three dimensional velocity vector elements at the measuring point, and the directional cosines of the sensors. The five sensor conductivity probe method proposed in this study is based on the four sensor probe method. With the five sensor probe, the local IAC for a given referred measuring area of the probe can be predicted more exactly than the four sensor probe. In this paper, the mathematical approach of the five sensor probe method for measuring the IAC is described, and a numerical simulation is carried out for ideal cap bubbles of which the sizes and locations are determined by a random number generator.

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DEVELOPMENT OF AN ORTHOGONAL DOUBLE-IMAGE PROCESSING ALGORITHM TO MEASURE BUBBLE VOLUME IN A TWO-PHASE FLOW

  • Kim, Seong-Jin;Park, Goon-Cherl
    • Nuclear Engineering and Technology
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    • v.39 no.4
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    • pp.313-326
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    • 2007
  • In this paper, an algorithm to reconstruct two orthogonal images into a three-dimensional image is developed in order to measure the bubble size and volume in a two-phase boiling flow. The central-active contour model originally proposed by P. $Szczypi\'{n}ski$ and P. Strumillo is modified to reduce the dependence on the initial reference point and to increase the contour stability. The modified model is then applied to the algorithm to extract the object boundary. This improved central contour model could be applied to obscure objects using a variable threshold value. The extracted boundaries from each image are merged into a three-dimensional image through the developed algorithm. It is shown that the object reconstructed using the developed algorithm is very similar or identical to the real object. Various values such as volume and surface area are calculated for the reconstructed images and the developed algorithm is qualitatively verified using real images from rubber clay experiments and quantitatively verified by simulation using imaginary images. Finally, the developed algorithm is applied to measure the size and volume of vapor bubbles condensing in a subcooled boiling flow.

Investigation of vapor-liquid equilibrium of HFC-32/143a and HFC-143a/134a systems (HFC-32/143a와 HFC-143a/134a계의 기-액상평형 실험에 관한 연구)

  • Kim, C.N.;Park, Y.M.
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.11 no.1
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    • pp.91-99
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    • 1999
  • Vapor-liquid equilibrium apparatus is designed and set up. The equilibrium data of two binary systems, HFC-32/143a and HFC-143a/134a, are measured. Fifteen equilibrium data for HFC-32/143a and HFC-143a/134a systems are measured over the temperature range 263.15~283.15K at 10K interval and the composition range 0.10~0.80, respectively. And vapor-liquid equilibrium data are calculated using equation of state and correlation of activity coefficient and compared with the present data. Equation of state is used CSD and RKS equations and correlation of activity coefficient is used Margules' and Van Ness and Abbott's correlations. Real behavior of HFC-32/143a system has very large deviation with Raoult's rule which is ideal behavior. But real behavior of HFC-143a/134a system is similar to ideal behavior. The calculated data from CSD equation are compared with the data in the open literatures and the calculated data from REFPROP. In the results for REFPROP, the relative deviations of bubble point pressure for HFC-32/143a system are within -2.16~0.84% for CSD equation and within -0.20~1.10% for RKS equation. And the relative deviations of bubble point pressure for HFC-143a/134a system are within -0.45~0.12% and -0.20~2.8% for CSD and RKS equations, respectively.

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The Importance of Filter Integrity Test to Ensure Sterility of Radiophamaceuticals for Using PET Image

  • Cho, Yong-Hyun;Park, Jun-Hyung;Hwang, Ki-Young;Kim, Hyung-Woo;Lee, Hong-Jae;Kim, Hyun-Ju
    • The Korean Journal of Nuclear Medicine Technology
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    • v.12 no.1
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    • pp.74-77
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    • 2008
  • The radiopharmaceuticals are routinely injected to blood vessel for acquiring PET image. For this reason, It is imperative that they undergo strict quality control measures. Especially, Sterility test is more important than any other quality control procedures. According to the FDA guideline, It requires filter integrity test used in the processing of sterile solutions. Among several methods, we can decide to use bubble point test. We usually use vented GS-filters (Millipore co., USA) which are sterilizinggrade (0.22 um pore size) and are placed upper site on product vial. After the synthesis of $^{18}F$-FDG, solutions wet the membrane in filter and then go into the product vial. By all synthesis steps have finished, we can observe the presence of the bubbles in the product vial. Since we have started this study, we have never found any bubbles in the product vial. Because the maximum pressure intensity of the filter which has set by manufacturer is up to 5 bars, but helium gas pressure is up to 1 bar in our module system. So, we can make 5 bars pressure using helium gas bombe and increase pressure up to 5 bars step by step. However, it does not happen to anything in vial.

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The Magnus Effect of a Rotating Circular Cylinder near a Plane Wall (벽면근처에서 회전하는 원주의 마그너스 효과)

  • Ro, Ki-Deok;Kim, Kwang-Seok
    • 한국가시화정보학회:학술대회논문집
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    • pp.42-47
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    • 2006
  • The flow around a rotating circular cylinder near a plane wall is investigated by the measurement of the lift acting on the cylinder and by the flow visualization using the hydrogen bubble technique in the circulating water tank. The experimental parameters are the rotating direction of the cylinder, the space ratios H/D$(H/D=0.05\sim0.5)$ between cylinder and plane wall and the velocity ratios $\alpha(\alpha=0\sim{\pm}2.0)$. In the case of clockwise, the lift on the rotating circular cylinder was increased with the reduction of the space ratios and with the velocity ratios, the upper separation point was more shifted in the rotating direction with them. In the case of anticlockwise, the absolute value of the lift on the rotating circular cylinder was increased with the space ratios and with the velocity ratios, the lower separation point was more shifted in the rotating direction with them.

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Formation and Crystallization of Calcium Carbonate in $C_2H_5OH-Ca(OH)_2-CO_2$ System by Ceramic Bubble Plate Reactor. (Ceramic Bubble Plate를 이용한 $C_2H_5OH-Ca(OH)_2-CO_2$계의 탄산칼슘 생성 및 결정화 연구)

  • Ahn, Ji-Whan;Park, Chan-Hoon
    • Resources Recycling
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    • v.5 no.3
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    • pp.56-64
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    • 1996
  • C,H,OH system is widely used for producing synthetic beverages and pharmaceuticals. Calcium hydroxide suspension was used to callhol the morphology of calcium carbonate, and the charactenstics of the formahan and crystsllizatian of calcium cilrbonate by adding ethylenc glycol were determined A reaclor was made with attaching a ceramic bubble plate, and lhe eleclrical conductivity was continously monitored during the rcaction with CO, gas. A part of the suspension was separated and powdered at the transition point. XRD and electron microscopic observation showed that the intermedmte and final products were vilterite, ;~r;lganite and calcite. In this study, the volumc of the ethylene glycol added to CH,OH was fixed a1 10 vol\ulcornerh. The valumc of the suspension was 500 ml, and the changes oi characteristics were shdied along with variims cnntents(l0-50 g) of calcium hydroxide. Except m the case of 10 g of calcium hydroxide at the crystallization stagc, all of products showed gelation. Tne marc the calcium hydroxide the shorter the formation time. Alsa. the farmalion of spherical valcrile ivas obsemcd when 30 g Ca(OH), was added. Tne vaterite(a compound material) can bc synthesised under alnbienl pressure and lempcmhre m a C,H,OH system by morphology control. Even though the vateritc was meta-stable phasc and could bc changed to calcitc easily, the stable and spherical vateritc was observed by using G5 glass fillers and vacuum dricrs.

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Test and Evaluation for Time Delay Function of Point Detonating Fuze by Underwater Sound Analysis (수중음향 분석을 통한 충격신관 지연기능 시험평가)

  • Na, Taeheum;Jang, Yohan;Jeong, Jihoon;Kim, Kwanju
    • Journal of the Korea Institute of Military Science and Technology
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    • v.20 no.2
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    • pp.217-224
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    • 2017
  • This study proposes an evaluation method for time delay function(TDF) of Point Detonation(PD) fuse using underwater explosion and water entry phenomena. Until now, nothing but the naked eyes of an observer or video images have been used to determine whether the TDF of PD fuze is operated or not. The observer has verified the performance of TDF by analysing the shape of the plume formed by underwater explosion. However, it is very difficult to evaluate the TDF of PD fuse by these conventional methods. In order to overcome this issue, we propose a method using underwater sound signal emitted from the underwater explosion of high explosive charge. The result shows that the measured sound signal is in accord with the physical phenomena of water entry of warhead as well as underwater explosion. Also, from the hypothesis test of bubble period, difference on underwater sound analysis between dud event and delay one is proved.

The Flow Field Characteristics of a Rotating Circular Cylinder near a Plane Wall (벽면에 근접해서 회전하는 원주의 유동장 특성)

  • Kang, Myung-Hun;Kim, Kwang-Seok;Ro, Ki-Deok
    • Journal of Advanced Marine Engineering and Technology
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    • v.31 no.2
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    • pp.166-172
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    • 2007
  • The flow around a rotating circular cylinder near a plane wall is investigated by the measurement of the lift acting on the cylinder and by the flow visualization using the hydrogen bubble technique in the circulating water tank. The experimental parameters are the rotating direction of the cylinder. the space ratios $H/D(H/D=0.05{\sim}0.5)$ between cylinder and plane wall and the velocity ratios ${\alpha}({\alpha}=0{\sim}{\pm}2.0)$. In the case of clockwise, the lift on the rotating circular cylinder was increased with the reduction of the space ratios and with the velocity ratios, the upper separation point was more shifted in the rotating direction with them. In the case of anticlockwise, the absolute value of the lift on the rotating circular cylinder was increased with increasing the space ratios and the velocity ratios. the lower separation point was more shifted in the rotating direction with them.

The Magnus Efface of a Rotating Circular Cylinder Near a Plane Wall (벽면 근처에서 회전하는 원주의 마그너스 효과)

  • Ro, Ki-Deok;Kim, Kwang-Seok;Oh, Se-Kyeong
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.31 no.11
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    • pp.957-962
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    • 2007
  • The flow around a rotating circular cylinder near a plane wall is investigated by the measurement of the lift acting on the cylinder and by the flow visualization using the hydrogen bubble technique in the circulating water tank. The experimental parameters are the rotating direction of the cylinder, the space ratios H/D($H/D=0.05{\sim}0.5$) between cylinder and plane wall and the velocity ratios ${\alpha}({\alpha}=0{\sim}{\pm}2.0)$. In the case of clockwise, the lift on the rotating circular cylinder was increased with the reduction of the space ratios and with the velocity ratios, the upper separation point was more shifted in the rotating direction with them. In the case of anticlockwise, the absolute value of the lift on the rotating circular cylinder was increased with the space ratios and with the velocity ratios, the lower separation point was more shifted in the rotating direction with them.

Flow Control Around a Circular Cylinder Using Two Splitter Plates (두 개의 분할판을 이용한 원형 단면 실린더의 유동제어)

  • Hwang, Jong-Yeon;Yang, Kyung-Soo
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.28 no.2
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    • pp.127-134
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    • 2004
  • Control of drag force on a circular cylinder using multiple detached splitter plates is numerically studied for laminar flow Two splitter plates with the same length as the cylinder diameter (d) are placed horizontally in the upstream of the cylinder and in the near-wake region, respectively. Their positions are described by the gap ratios (G$_1$/d, G$_2$/d), where G$_1$ represents the gap between the cylinder stagnation point and the rear edge of the upstream splitter plate, and G$_2$ represents the gap between the cylinder base point and the leading edge of the rear splitter plate. The drag varies with the two gap ratios; it has the minimum value at a certain set of gap ratios for each Reynolds number The upstream splitter plate decreases the stagnation pressure, while the rear splitter plate increases the base pressure by suppressing vortex shedding. This combined effect causes a significant drag reduction on the cylinder Particularly, the drag sharply increases past an optimum G$_2$/d; this seems to be related to a sudden change in bubble size in the wake region.