• Title/Summary/Keyword: 전체신장율

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Edge-flame Instability in A Low Strain-rate Counterflow Diffusion Flame (저신장율 대향류확산화염에서 에지화염 진동불안정성)

  • Park, June-Sung;Kim, Hyun-Pyo;Park, Jeong;Kim, Song-Cho;Kim, Jeong-Soo
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2006.11a
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    • pp.295-298
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    • 2006
  • Experiments in methane-air low strain rate counterflow diffusion flames diluted with nitrogen have been conducted to study the behavior of flame extinction and edge flame oscillation in which lateral conduction heat loss in addition to radiative heat loss could be remarkable at low global strain rates. Onset conditions of edge flame oscillation and flame oscillation modes are also provided with global strain rate. It is seen that flame length is closely relevant to lateral heat loss, and this affects flame extinction and edge flame oscillation. Edge flame oscillations in low strain rate flames are categorized into three: a growing oscillation mode, a decaying oscillation mode, and a harmonic oscillation mode. The regime of flame oscillation is also provided at low strain rate flames.

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A Study on Transition of Flame Extinction at Low Strain Rate Counterflow Flames (저신장율 대향류화염에서 화염소화에 있어서 천이에 대한 연구)

  • Park, Dae-Geun;Park, Jeong;Kim, Jeong-Soo;Bae, Dae-Suk
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2009.11a
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    • pp.197-201
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    • 2009
  • Experiments were conducted to study the transition of shrinking flame disk to flame hole in counterflow diffusion flames. The studies of transition are well described by varying burner diameters, global strain rate and velocity ratio. It is experimentally verified that radial conduction heat loss is affected at even high strain rate flames for appropriately small burner diameters. It is also shown that flame extinction modes are grouped into three and particularly, hole or stripe is observed in sufficiently high strain rate flames. There exists critical radius according to burner diameter which divide flame extinction modes into three parts.

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Oscillatory Instabilities of Edge Flames in Solid Rocket Combustion (고체연료로켓에서 에지화염의 맥동 불안정성)

  • Kim Kang-Tae;Park Jun-Sung;Park Jeong;Kim Jeong-Soo;Keel Sang-In;Cho Han-Chang
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2006.05a
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    • pp.275-278
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    • 2006
  • Systematic experiments in $CH_4/Air$ counterflow diffusion flames diluted with He have been undertaken to study the oscillatory instability in which lateral heat loss could be remarkable at low global strain rate. The oscillatory instability arises for Lewis numbers greater than unity and occurs near extinction condition. The dynamic behaviors of extinction in this configuration can be classified into three modes; growing, harmonic and decaying oscillation mode near extinction. As the global strain rate decreases, the amplitude of the oscillation becomes larger. This is caused by the increase of lateral heat loss which ran be confirmed by the reduction of lateral flame size. Oscillatory edge flame instabilities at low global strain rate are shown to be closely associated with not only Lewis number but also heat loss (radiation and lateral heat loss).

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A Comparative Survey on Misconception and Desire for Physique of College Women in Taegu and Fukuoka (한.일 여대생의 자기 체형 인식 및 체형 불안도에 관한 비교 연구)

  • Hong, Jin-Pyo;Choi, Bong-Soon
    • Journal of the Korean Society of Food Culture
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    • v.15 no.5
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    • pp.435-442
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    • 2000
  • This study was carried out to investigate misconception for physique and desire for physique of college women in Taegu(412 subjects) and Fukuoka(423 subjects). The data was collected by questionnaire interview and anthropometric measurement. The results were as follows : The mean age, height, weight, and BMI of Taegu subjects were $19.9{\pm}1.2$ years old, $159.6{\pm}4.9cm,\;51.2{\pm}6.0kg\;and\;20.1{\pm}2.2$, respectively. The mean age, height , weight, and BMI of Fukuoka subjects were $18.3{\pm}0.6$ year old, $157.5{\pm}5.0cm,\;53.3{\pm}6.9kg\;and\;21.5{\pm}2.5$, respectively. The average ideal height desired by subjects in Taegu was higher than their real mean height by 5.1cm ; while the average ideal weight desired by subjects was lower than real mean weight by 2.6kg. The average ideal height desired by subjects in Fukuoka was higher than their real mean height by 3.2cm ; while the average ideal weight desired by subjects was lower than real mean weight by 5.4kg. The percentage of Taegu subjects who desired to be slender, be fatty and maintain weight were 70.1%, 7.3%, and 22.6% respectively. The percentage of Fukuoka subjects who desired to be slender, be fatty and maintain weight were 85.3%,2.6% and 12.1% respectively. The rate of misconception for the actual physique was 56.5% in Taegu subjects, and 57.2% In fukuoka subjects. The over estimation rate was higher in subjects desired for slenderness than in others. The adolescent females having a fatty body image in self-consciousness indicated that they felt high social physique anxiousness. Finally, the rate of misconception and the degree of social physique anxiousness were higher in those who had a desire for slenderness.

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Study on the Evaluation of Renal Function According to Set a Partial Region of Interest in 99mTc-DMSA scan of the Pediatric Patient with a Duplicated Ureter (중복요관을 가진 소아환자의 99mTc-DMSA 검사에서 부분적 관심영역 설정에 따른 신기능 평가에 관한 연구)

  • Nam-Koong, Hyuk;Oh, Shin Hyun;Kim, Jung Yul;Choi, Yoon Jung;Kim, Jae Sam;Lee, Chang Ho
    • The Korean Journal of Nuclear Medicine Technology
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    • v.17 no.1
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    • pp.43-47
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    • 2013
  • Purpose: A duplicated ureter is congenital renal malformations with ureter in two. Patients with duplicated ureter are in force to $^{99m}Tc-DMSA$ scan at surgery before and after. In existing examination, at produce result after $^{99m}Tc-DMSA$ scan, didn't compare to upper pole and lower pole with malformed kidney and compared to only relative uptake ratio. Therefore, this study will examine about utility of set a partial region of interest and to functional recovery of renal cell through change of upper pole uptake ratio of malformed kidney by setting each partial region of interest in upper pole and lower pole of malformed kidney in $^{99m}Tc-DMSA$ examination in surgery before and after. Materials and Methods: Pediatric patients with malformed kidney of incomplete duplicated ureter, 15 patients were enrolled in this study. Scanning were scan 3 to 4 hours after injection of $^{99m}Tc-DMSA$ 1.5 ~ 1.9 MBq/kg. Region of interest were each set in normal kidney, upper pole and lower pole with malformed kidney. Region of interest were set with same condition and method to images of surgery before and after that radio technologist 1 person, resident of nuclear medicine 1 person and doctor of urology together. Therefore, this study were compared to uptake ratio (A: B: C) that normal kidney (A), lower pole of malformed kidney (B) and upper pole of malformed kidney (C) about uptake ratio changes of malformed kidney in follow-up examination of surgery before and after. Results: When compared to 15 patients, uptake ratios were increased 7 persons and decreased 8 persons. Among increased 7 persons, it were periods of follow-up examination that 2 persons were 14 months, 4 persons were 12 months and 1 person was 8 months after surgery. Among decreased 8 persons, it were periods of follow-up examination that 4 persons were 12 months 3 persons were 6 months and 1 persons were 4 months after surgery. Conclusion: Existing study could not see the exact uptake ratio changes of malformed kidney because using only the overall Left-Right kidney uptake ratios. But a setting partial region of interest was able to see exactly what changes in the uptake of each upper pole and lower pole of malformed kidney. Because recovery of renal parenchymal cells is difficult in an evaluation of short period of time, follow-up examination should be made in long period of time. How to set up partial region of interest be thought that it would be useful.

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Determination of Representative Renal Depth for Accurate Attenuation Correction in Measurement of Glomerular Filtration Rate in Transplanted Kidney (이식 신의 사구체 여과율 측정에서 정확한 감쇄 보정을 위한 신장 깊이 대표값 설정)

  • Oh, Soon-Nam;Kim, Sung-Hoon;Rha, Sung-Eun;Chung, Yong-An;Yoo, Ie-Ryung;Sohn, Hyung-Sun;Lee, Sung-Young;Chung, Soo-Kyo
    • The Korean Journal of Nuclear Medicine
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    • v.36 no.4
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    • pp.271-276
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    • 2002
  • Purpose: To measure reliable glomerular filtration rate by using the representative values of transplanted renal depths, which are measured with ultrasonography. Materials and Methods: We included 54 patients (26 men, 28 women), with having both renal scintigraphy and ultrasonography after renal transplantation. We measured GFR with Gates' method using the renal depth measured by ultrasonography, and median and mean ones in each patient. We compared GFR derived from ultrasonography-measured renal depth with GFR derived from median and mean renal depths. The correlation coefficients were obtained among GFR derived from ultrasonography-measured renal depths, median and mean renal depths under linear regression analysis. We determined whether GFR derived from median or mean renal depth could substitute GFR derived from ultrasonography-measured renal depth with Bland-Altman method. We analyze the expected errors of the GFR using representative renal depth in terms of age, sex, weight, height, creatinine value, and body surface. Results: The transplanted renal depths range from 3.20 cm to 5.96 cm. The mean value and standard deviation of renal depths measured by ultrasonography are $4.09{\pm}0.65cm$ in men, and $4.24{\pm}0.78cm$ in women. The median value of renal depths measured by ultrasonography is 4.36 cm in men and 4.14 cm in women. The GFR derived from median renal depth is more consistent with GFR derived from ultrasonography-measured renal depth than GFR derived from mean renal depth. Differences of GFR derived from median and ultrasonography-measured renal depth are not significantly different in the groups classified with creatinine value, age, sex, height, weight and body surface. Conclusion: When median value is adapted as a representative renal depth, we could obtain reliable GFR in transplanted kidney simply.

A Study of the Degree of Obesity in Elementary School Students according to Grade and Gender (초등학생의 학년별 성별 비만실태)

  • Cho, In-sook;Park, In-hyae;Ryu, Hyun-sook;Park, Yo-sup;Hwang, Sen-lye;Ahan, hyun-hee
    • Journal of agricultural medicine and community health
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    • v.31 no.2
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    • pp.177-185
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    • 2006
  • Objectives: This study was carried out with 31, 519(16,653 boys, 14,857 girls) of elementary school students to investigate the prevalence of obesity at a district in Gwangju City. It can be applied to develope an educational program of the obesity control as basic data in this local area Methods: The data collected from May, 2004 to July, 2004 were analyzed by SAS PC+ 8.0 program. Children were selected depending on criteria from obesity index (%) by using physical index (height, body weight), and then subjects were classified into one of three groups according to the degree of obesity: mild(20~29.9%), moderate(30~49.9%), and severe($?50%{\cdot}$) obesity. Results: It showed that male elementary school students were higher and heavier than female elementary school students(p< .001) in every grade except the 4th grade(height) and the 6th grade ( body weight). The obesity rates of male students(11.6%) showed higher(p< .001) than those of female students(8.8%). Specially the 4th grade elementary school boys were higher than any other groups in obesity(13.7%). As a whole, the prevalence of obestiy showed mild(5.9%), moderate(3.8%), and severe(0.6%). Male students showed higher rate of obesity than those of female students. The obesity of male students showed higher rate than that of female students except 2-3rd grade elementary school students(p< .001). The obesity of 4~6th grade elementary school students showed higher rate than those of 1~3rd grade students(p< .001). Conclusions: The obesity rates of male students are higher than that of female students, and the obesity rates of 4~6th grade students are higher than those of 1-3rd grade students in the elementary school. Additionally, these results suggest that the program may be needed to prevent obesity of children.

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An Experimental Study on Heat Transfer Characteristics of Synthetic Gas($H_2/CO$)Air Premixed Flames in an Impinging Jet Burner - Part 1 : Stretched Lift-off Flames (충돌제트 버너에서 합성가스($H_2/CO$) 공기 예혼합 화염의 열전달 특성에 관한 실험적 연구 - Part 1 : 스트레치된 부상 화염)

  • Kang, Ki-Joong;Jo, Joon-Ik;Lee, Kee-Man
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2011.04a
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    • pp.453-456
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    • 2011
  • An experimental investigation of the heat transfer characteristics of stretched premixed flames using Synthetic gas has been performed. Hydrogen and carbon mon-oxide which could be extracted from coal gasification process are the main fuel of synthetic-gas. Heat flux at the stagnation point was increased as global strainrate was increased, then the heat flux was decreased when a global strainrate reached a sudden point. Heat flux at the stagnation point is also affected by nozzle to impingement distance. Heat flux was increased as nozzle to impingement place distance was increased. This study is a foundation study of practical use of secondary gases from coals.

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Effects of processing conditions on physical properties of alginate film (가공조건이 alginate 필름의 물리적성질에 미치는 영향)

  • YOU Byeong-Jin;SHIM Jae-Man
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.32 no.5
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    • pp.582-586
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    • 1999
  • The processing conditions for producing and edible alginate film from sea tangle were investigated by measuring water vapor permeability (WVP), tensile properties and colors of film. The alginates were extracted with $3\%$ sodium carbonate ($Na_2CO_3$) solution for 5 hrs, and the alginate films were prepared with extracted sodium alginates, D-gluconic acid lactone, $CaCO_3$ and various plasticizers, As the concentration of alginate in making the film was increased, the WVP and elongation of the film were decreased and the tensile strength was increased. The higher amount of plasticizer showed the higher WVP and elongation, and the order of various plasticizers in increasing the WVP and elongation of the film was glycerol, polyethylene glycol, and sorbitol. The addition of sorbitol in the film showed the highest value (89.57) in lightness of Hunter color system and the film added polyethylene glycol had the highest values (-1,12 and 11.4) in redness and yellowness.

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