Study on bubble and liquid velocities in an area-varying horizontal channel

Tran, Thanh Tram,Kim, Byoung Jae,Park, Hyun-Sik Elsevier 2018 Annals of nuclear energy Vol.118 No.-

<P><B>Abstract</B></P> <P>Two-fluid equations are widely used to simulate thermal-hydraulic phenomena in a nuclear reactor. Simulation accuracy depends on the modeling terms in the two-fluid equations. For a dispersed flow, the overall two-phase pressure drop by wall friction must be apportioned to each phase in proportion to the fraction of each phase (Kim et al., 2014). By applying this approach, the prediction of bubble phase velocity can be close to that of liquid for a fully developed flow in a horizontal pipe with a constant area. One may want to know what would happen in the area-varying channels. It is always true that the bubble density is much lower than the water density. Hence, the bubble would accelerate faster than the liquid in a nozzle in which the pressure decreases along the downstream; the bubbles would decelerate more quickly than the liquid in a diffuser in which the pressure increases along the downstream. The purpose of this study was to investigate those behaviors in an area-varying channel using the experimental data and MARS simulations. Experiments were made of turbulent bubbly flows in an area-varying horizontal channel. The velocities of two phases were measured with the help of the PIV technique. The experimental result showed that the two-phase velocities were no longer close to each other in the area-varying regions. The bubble was faster than the liquid in the nozzle region; in contrast, the bubble was slower than the liquid in the diffuser region. MARS code simulations were performed to assess the wall drag model. By replacing the original wall drag partition model in the MARS code with Kim’s one, the simulation results were consistent with experimental observations.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Bubble and water velocities in an area-varying channel are measured. </LI> <LI> The phase velocities are very close in the constant-area region. </LI> <LI> The bubble is faster than the water in the contraction region. </LI> <LI> The bubble is slower than the water in the diffuser region. </LI> <LI> Kim’s wall drag partition model well predicts experimental results. </LI> </UL> </P>

심혈관계 질환으로 관상질환 집중치료실에 입원한 환자들의 혜후 측정을 위한 APACHEⅢ점수 체계의 임상적 유용성

이공섭,이창선,최현주,홍종서,강지향,김도형,이민영,오인균,김병엽,김상억,김학찬,한승혜,이재용,지영우,안경주 대한순환기학회 2000 Korean Circulation Journal Vol.30 No.8

국부의치용 금속인 Ni-Cr alloy와 Co-Cr alloy의 주조후 냉각방법에 따른 표면조직과 경도의 비교 연구

김재도,김병식,김주원 대구산업정보대학 2002 논문집 Vol.16 No.-

The purpose of this study was to investigate the relationship between the micro-structure and hardness of Ni-Cr alloy(Talladium™ alloy) and Co-Cr alloy(Wironium^(?) extra-hard alloy), which are widely used as partial denture frame work these days, depending on the cooling method, followed by casting. The frist group was bench cooled at room temperature(20℃), the second group was slowly cooled in the furnace from 700t to room temperature, and third, rapidly cooled in 20~22℃ water. The micro-structures of each specimen were compared by means of photomicrograph taken by metallurgical microscope. In addition to the physical characteristics of each specimen were obtained using the Rockwell C Scale. The results were obtained as follows: 1) The hardness value of Talladium™ alloy appeared higher than the Wironium^(?) alloy. 2) The hardness value of the slow cooling method(in the furnace) appeared higher the than the bench cooling method, water cooling method. 3) The grain particle in the slowly cooled alloy were much finer than the bench cooling method, water cooling method. 4) In the cooling method of Talladium™ alloy and Wironium^(?) alloy for partial denture the slow cooling method was considered more profitable than the bench cooling method, water cooling method.

이성질체 분리를 위한 음이온교환재료의 합성

김재훈,김민,김병식 한국공업화학회 2003 응용화학 Vol.7 No.2

Anion exchange groups were introduced into porous hollow fiber membranes by radiation-induced ploymerization. The epoxy group produced in the GMA-grafted hollow fiber membrane was converted into anion-exchange groups by reaction with Diethylamine(DEA). Triethylamine(TEA). Ethanolamine(EtA). Diethanolamine(DEtA). The D-, L-Tryptophan solution was forced to permeate across the hollow fiber DEA, TEA, EtA, DEtA memberan. When measurements of anion-exchange capacity of the DEA, TEA, EtA, DEtA memberan, the DEA membrane having higher adsorption capacity than TEA, EtA, DEtA membrane.

시각장애인 주택의 실태 및 요구도 분석에 관한연구

김상운,강병근,성기창,박광재,윤영삼,정은영 한국의료복지시설학회 2009 의료·복지 건축 Vol.15 No.1

Increasing the old and the senile disability, it is increased that the demand of barrier free house for the disabled the senior the pregnant and the young is strongly increasing recently. In this reason, this study focuses the problems of the house which is used by the Blind through the investigation of current status and tries to find out the differences between disability's demend and current design of their house. As well, through the research and analysis some cases of the residential alterations this study verifies what the demand is on each room and their need is committed correctly during the residential alterations. It is the purposes of this study finding the problems through these research and analysis Thus this study investigates houses of the Blind and finds out their house type scale and daily Iife through the statisticaI data and documentary survey and also investigates current status of their house. The basic standard for the current status and the demand analysis is researched by the barrier factors which are deducted from the former study.

BSA고정화를 위한 가교제의 첨가특성

김재훈,김민,김병식 한국공업화학회 2004 응용화학 Vol.8 No.2

Anion exchange groups(DEA) were introduced into porous hollow fiber membranes by radiation-induced ploymerization. A DEA group-containing polymer chain grafted onto a porous PE membrane. The BSA solution was forced to permeate across the hollow fiber DEA membrane. BSA was immobilized by the permeation of a BSA solution through the pore of the DEA membrane. The immobilized BSA was cross-linking with glutaraldehyde to prevent leakage. Afterwards, The GA 0.05 percent membrane having higher adsorption capacity than 0.025, 0.075, 0.1 percent GA concentration.

적외선 카메라 이용한 금속 내부 결함 평가에 관한 연구

김병희,김재열,최철준 朝鮮大學校 機械技術硏究所 2006 機械技術硏究 Vol.9 No.1

RT and UT are largely used as a non-destructive assessment of welding defects. RT shows difficulty in radioactive exposure and real-time detection. UT shows difficulty in quantitative detection of defects, and examination of a wide area in a short time. In order to settle the aforementioned disadvantages, many researchers try to find solution. In this paper, we apply a new examination method to verify the effectiveness in order to supplement the disadvantages of UT and RT, the existing non-destructive methods. The new method proposed in this paper is to use a difference in heat conductivity. If there is a discontinuous part, that is an internal defect. there is a difference in heat conductivity. Using this fact, it is possible to check the existence of an internal defect due to a temperature difference on the part with a defect and the part without a defect when the welded part is heated. The temperature difference on the surface indicated by the difference in heat conductivity can be checked for a wide area within a short time, by means of a thermal Image camera thereby to settle the disadvantage of the conventional non-destructive inspection methods. The thermal image method, however, has a disadvantage in that thermal load must be given to the tested sample and it is difficult to quantify measured data. In order to overcome this disadvantage, we will describe preliminary test and the like for applying thermal load on the tested sample including a welding defect, photographing images by means of a thermal image camera, analyzing thermal images, and analyzing welding defects.

Glutaraldehyde로 가교시킨 BSA고정막에 의한 DL-Tryptophan의 흡착특성

김재훈,김민,김병식 한국공업화학회 2004 응용화학 Vol.8 No.1

A DEA group-containing polymer chain grafted onto a porous PE membrane. BSA was immobilized by the permeation of a BSA solution through the pore of the DEA membrane. The immobilized BSA was cross-linking with glutaraldehyde to prevent leakage. DL-tryptophan solution was forced to permeate through the BSA immobilized membrane at a flow 50mL/h. As a result, Adsorption of D-L-tryptophan increase with increasing of BSA immobilized as a function of the degree of GMA grafting.

HFCVD법을 이용하여 제작한 n-형 다이아몬드 박막의 특성 연구

김병규,황윤식,권민철,김용,이재열,박홍준 동아대학교 기초과학연구소 2000 基礎科學硏究論文集 Vol.17 No.1

HFCVD법으로 암모니아 가스를 사용하여 n-형 도핑된 다이아몬드 박막을 제작하여, 기판온도와 암모니아 가스 첨가비에 따른 박막의 morphology의 변화를 조사하였다. 증착된 시료에 대한 SEM, Raman, XRD를 이용하여 박막의 특성을 분석하고, 도핑에 따른 전계방출 특성을 측정하였다. 양질의 n-형 도핑된 다이아몬드 박막을 증착시키기 위해 기판온도와 암모니아 첨가비에 따른 최적의 증착조건을 찾을 수 있었다. We fabricate n-doped diamond thin films by hot filament chemical vapor deposition method(HFCVD) using ammonia as a doping gas and investigate the effect of the substrate temperature and the ammonia gas ratio upon the diamond film morphology. The SEM, Raman spectroscopy, and the XRD analysis are executed to characterize film morphology. Field emission property of the film is measured also. We find optimum conditions of the substrate temperature and the ammonia gas ratio to deposit high quality n-doped diamond thin films.

전신마취하에 치료한 환자에 대한 실태조사

김하나,백병주,김재곤,권병우,양연미 大韓小兒齒科學會 2006 大韓小兒齒科學會誌 Vol.33 No.2

소아환자를 진료하다 보면 불안과 공포가 극도로 심하여 일반적인 행동조절법으로는 양질의 치과치료가 불가능한 상황에 자주 접하게 된다. 음성조절과 신체 속박 또는 입 가리기 등의 강압적이고 물리적인 방법을 사용하여도 역시 치료결과가 만족스럽지 않고 이러한 경우 환자와 보호자에게 가해지는 정신적인 상해는 결코 무시할 수 없다. 따라서 행동 조절의 어려움과 치과 질환의 심각성 등으로 인해 전신마취하의 치과치료가 필요한 경우가 많으며 이 경우 전신마취는 행동조절법의 하나로 간주될 수 있다. 치과전신마취는 비용이 많이 드는 것과 적지만 있을 수 있는 부작용의 위험성을 가지고 있다. 그러나 환자의 내원 횟수를 줄일 수 있고 치과치료에 대한 부정적인 행동반응을 유발하지 않아 의사와 환자의 스트레스를 줄일 수 있으며 양질의 진료가 가능하다는 점에서 장점을 갖는다. 이번 실태조사는 2000년 12월부터 2005년 4월까지 전북대학교 치과병원 소아치과에서 전신마취하에 광범위한 치과치료를 받은 200여명의 환자를 대상으로 하여 나이, 성별 등의 인적 사항, 전신마취가 필요했던 이유, 전신마취시간, 치료의 종류, 전신마취횟수 등에 관하여 조사하였다. Dental caries in children has declined over the past few decades. However, Certain populations of children experience high levels of dental disease. To perform the highest quality dental care for the pediatric patient, the practitioner may need to use pharmacological means to obtain a quiescent, cooperative patient. Furthermore, complex treatment can impose high demands on the very young, making use of general anesthesia the preferred approach for some patients. General anesthesia is widely used to provide comprehensive dental treatment for children in USA and Europe and Scandinavia etc. Parental and patient satisfaction following completion of dental care under general anesthesia is reportedly high. Dental general anesthesia has disadvantage that it is expansive and carries a small but significant risk of mortality. However, It has the advantage of permitting treatment at a single visit, allowing immediate relief of pain and requiring little or no cooperation from the child. Rampant caries was the major indication for use of general anesthesia in the youngest age group or medically compromised patients. This study describe the characteristics of patient receiving comprehensive dental treatment under general anesthesia at the pediatric dentistry of Chonbuk National University Hospital in Jeonju. Korea in the 4year period between December 2001 and April 2005.