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

초등학교 고학년 학생의 구강보건에 관한 인식 및 행동

김영경,문혁수,정재연,한수진,이병진,김은경,정혜련 韓國學校保健學會 2001 韓國學校保健學會誌 Vol.14 No.1

The purpose of this study was to collect basic data for the development of effective oral health education program in elementary school. The subjects in this study were 604 fourth-year, fifth-year and sixth-year students of an elementary school in Seoul. Oral health awareness and behaviors were surveyed and analyzed. The findings of this study were as follows: 1. The most common time for toothbrushing was after dinner(62.0%) and before bedtime(62.3%). By school year, the largest number who brushed their teeth after dinner were fourth and fifth graders while the greatest number who did so after breakfast were sixth graders Seventy-four percent of respondents brushed the teeth twice or more a day. By school year, the fifth-year students brushed their teeth the least while girls outperformed the boys in daily toothbrushing frequency(p<0.05). Regarding the intake of cariogenic food, 62.1% took that kind of food once or more a day. By school year, the fifth graders took the most (p<0.05), and girls took more cariogenic food than the boys(p<0.05). 2. Ninety percent of the respondents had visited a dental clinic. By grade, the sixth-year students had visited a dental clinic more frequently and girls more frequently than boys. Eighty percent of the respondents visited a dental clinic to receive treatment but just 12.3% visited a dental clinic to prevent oral diseases. Concerning the fetor of dental treatment only 14.4% expressed fear. School year made no difference, yet the percentage of girls who experienced fear was higher than that of boys(P<0.05). Regarding preventive treatment, 39.7% experienced pit and fissure sealing and 24.2% experienced the application of fluorides. All the students hadn't much experience in preventive treatment regardless of school year -- gender didn't make a difference. 3. Fourty-six percent of respondents had a preference for the fluoride mouth rinsing program; 38.4% wanted that grogram to continue. As to the reason for preference, 38.2% preferred it because of the prevention of dental caries, 43.0%, the largest percentage, didn't favor it because they found it too much trouble to do(some of the respondents gave two different answers). 4. Despite an increase in the frequency of toothbrushing at the right time, they still took cariogenic food frequently Their visit to a dental clinics also aimed at treatment more than at prevention, and they had very narrow experience of preventive treatment. Furthermore, the fluoride mouth rinsing program failed to draw their interest. Therefore, it is recommended that a successful real health education program should be developed.

Methylation이 心筋細胞膜에서의 ATP에 의한 Calcium Transport에 미치는 影響

金柱炳,昔廷鎬,李載欣 충남대학교 의과대학 지역사회의학연구소 1988 충남의대잡지 Vol.15 No.2

For the purpose of studying the properties of calcium pump, the effect of methy lation on the ATP-induced Ca-transport in the isolated porcine sarcolemmal vesicles which were loaded with high KCI was investigated. 1) Ca-transport by ATP was increased significantly, compared to control sarcolemmal vesicles. 2) Ca-transport of the vesicles preincubated in the methylation medium without PM II was increased by ATP, but less than control sarcolemmal vesicles. 3) Ca-transport of the vesicles preincubated in the methylation medium with PM II was decreased by ATP in the KCl medium, but increased in NaCI medium. But Ca-transport by ATP in the methylated vesicles in the reaction medium (NaCI and KC1) was significantly decreased, compared with Ca-transport by ATP in the nonmethylated vesicles. From the above results, it was suggested that methylation of membrane protein by PM II can change the membrane properties or the activity of calcium ATPase transporting calcium.

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.

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.

국부의치 Framework용 비귀금속 합금의 경도에 관한 연구

金在道,金炳植 대구산업정보대학 1997 논문집 Vol.11 No.2

The hardness of four kinds of cr-co alloys and one kind of Titanium alloy, which are widely used as partial denture framework these days, were measured and the following result were obtained. The tested alloys of cr-co alloy are Vitallium alloy (AUSTENNAL Co., U.S.A), and Biosil alloy (DEGUSSA Co., GERMANY), and Wironium extra-hard alloy (BEGO Co., GERMANY), and Ticonium alloy (TICONIUM Co., U.S.A), and Titanium alloy are pure titanium. (OHARA Co., JAPAN). 1. The cr-co alloy showed higher value (331.46±2.73Hv-376.74±2.34Hv) (RHN-30N : about 53.72-57.88) than the pure titanium alloy one (211.76 ± 11.2Hv) (RHN-30N value : about 36.66). 2. The hardness value (376.74+2.34Hv) (RHN-30N : 57.88) of experimental Ⅱ alloy was the highest. 3. The hardness value (211.76±11.2Hv) (RHN-30N : 36.66) of experimental Ⅴ alloy was the lowest. 4. These results suggested that the method of bench cooling was more effective.

장애물 없는 주택 설계기준에 관한 연구 : 국내 공통주택의 무장애(barrier free) 설계수준 평가를 중심으로

김상운,박광재,강병근 한국의료복지시설학회 2004 의료·복지 건축 Vol.10 No.2

In this paper, the all units of residential housing that is not legislated in facility development law are analyzed and foreign design criteria that is related to barrier-free unit housing is comparing to domestic. Through the comparison in front door, living room, bathroom, bedroom, and kitchen, this paper aims to suggest internal barrier-free design criteria. This paper is limited to internal housing which are front door, living room, bedroom, bathroom, and kitchen. Also, the objectives of facility development law are U.S, Japan, German, and in case of U.S, UFAS is established by ADA, in Japan, Heart Building law and detail standard drawing are used, in German, DIN is used. The objective of domestic case study is the latest residential housings that are built over 2003. The flow of study is as follows ; First, the internal items of' residential housing are abstracted, and each item is checked in facility development law that is legislated in. Next, through comparison of domestic and foreign facility development law related to housing, common items are abstracted and detail standards are defined. Domestic residential housings are analyzed in those standards. Finally, the problems that is the result of analysis are analyzed and the barrier free design criteria is abstracted in unit housing. Also, more developed items and future study are suggested.

치과 방문 시 어린이와 부모의 치과 불안도의 상관 관계

김성희,백병주,김재곤,양연미,권병우 大韓小兒齒科學會 2005 大韓小兒齒科學會誌 Vol.32 No.2

어린이에게 있어서 치과 불안의 문제는 오랫동안 환자 행동조절의 문제로서 여겨져 왔으며 이러한 문제로 인해 치료 시의 비협조도, 치료 악속 취소 및 회피 둥이 발생할 수 있다. 따라서 치과의사 및 치과 팀에게 가능한 한 빨리 어린이의 치과 불안을 인지하여 적절히 대처할 것이 요구 되어진다. 한편, 부모의 치과 불안이 그들의 아이의 치과 불안과 치료 협조도에 영향을 줄 수 있음이 이전의 여러 연구들로부터 언급 되어지고 있다. 또한 치과 방문 결정의 주체가 어린이라기보다는 부모임을 고려할 때, 부모와 어린이 사이의 치과 불안도의 관계 규명이 중요하다 하겠다. 본 연구는 전북대학교 병원 소아치과에 내원한 3~10세(평균 연령 5.27세, 표준 편차 2.172세)의 어린이 78명(남아 45명, 여아 33명)과 그들의 부모 78명을 대상으로 하였으며, 치과 치료 전의 어린이의 치과 불안도 평가를 위해 Venham Picture Scale을, 부모의 치과 불안도 평가를 위해 Corah's dental anxiety scale을 사용하여 두 값을 비교하였다. 또한 어린이의 치료 시 협조도, 기질, 성별, 나이, 부모의 교육 정도를 평가하여 치과 불안도와 비교하였다. 이에 다음과 같은 결론을 얻었다. 1. 어린이의 치과 불안도와 부모의 치과 불안도 사이의 상관 분석 및 회귀분석에서 상호 관계성이 존재하였다(P<0.02). 2. 어린이의 치과 불안도와 치료 협조도사이의 상관 분석 및 교차 분석에서 음의 상호 관계를 나타내었다(P<0.001). 3. 어린이의 치과 불안도와 기질에 관한 Student's t-test에서 낮은 불안도와 높은 불안도 그룹의 네 가지 기질 평균 점수비교 시, 낮은 불안도 그룹에서 모두 약간 낮은 평균 점수를 보였으나 통계학적 유의차는 없었다(P>0.1) 4. 어린이의 치과 불안도와 어린이의 성별, 나이에 관한 Student's t-test에서, 여아에서 높은 불안도, 3~6세의 어린 그룹에서 높은 불안을 보였다(P<0.001). 5. 부모의 치과 불안도와 부모의 학력에 관한, Student's t-test에서, 대학교육을 받지 않은 저학력 부모 그룹에서 더 높은 불안도를 보였으나 통계학적 유의차는 없었다(P>0.1). In children, dental anxiety of dental treatment has been recognized as a source of problems in patient management for many years. Dental anxiety can be causes of negative cooperation, cancel and avoid of dental treatment. Therefore, dentist and dental team should recognize of child's dental anxiety as early as possible and manage appropriately. In previous studies, it is reported that parental dental anxiety affect dental anxiety and cooperation of their child. And it is parental decision which results in a child's visit to the dentist, rather than a child's decision in most cases. Therefore, it is important to identify the relationship of dental anxiety between child and parent. We estimated child's dental anxiety before dental treatment using Venham Picture Scale that is useful even a very young child and parental dental anxiety using Corah's dental anxiety scale. Then, two values above were compared. Child's cooperation, temperament, sex, age, parental education were estimated and compared with dental anxiety, too. The results were as follows: 1. There are positive relationship of dental anxiety between child and parent with the correlation analysis (P<0.02). 2. There are negative relationship of child's dental anxiety and child's cooperation with the correlation and regression analysis (P<0.001). 3. Low anxiety group has lower mean value of four temperament item with the Student's t-test. But, there is no statistical differences (P>0.1). 4. Girl and younger group have higher mean value of dental anxiety than boy and older group with the Student s t-test (P<0.001). 5. Low educated parents have higher mean value of dental anxiety than high educated parents with the Student s t-test (P>0.1).