• 한국가시화정보학회지
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• 제17권1호
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• pp.60-68
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• 2019

Flow visualizations have been carried out to analyze the characteristics of bubby flows exhausted from a venturi-type bubble generator with an air vent. For various design parameters and operating conditions of the bubble generator, the images of bubbly flows was recorded using a high-speed camera and a microscope. Then the amount and size distribution of bubble was evaluated by an image processing technique. The results show that for increasing the amount of bubble, it is more effective to reduce the venturi throat than to enlarge the air vent diameter. If the water flow rate increases, the bubble generation rate increases but reaches a status of saturation, whose condition depends on Reynolds number at a given air vent diameter. The bubble size increases as the diameter of venturi throat decreases and Reynolds number increases. However, the air vent diameter is not a significant factor on bubble size.

• Nuclear Engineering and Technology
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• 제51권5호
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• pp.1261-1271
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• 2019

Droplet size and distribution are important parameters determining venturi scrubber performance. In this paper, we proposed physical models for a maximum stable droplet size prediction and upper limit log-normal (ULLN) distribution parameters. For the proposed maximum stable droplet size prediction model, a Eulerian-Lagrangian framework and a Reitz-Diwakar breakup model are solved simultaneously using CFD calculations to reflect the effect of multistage breakup and droplet acceleration. Then, two ULLN distribution parameters are suggested through best fitting the previously published experimental data. Results show that the proposed approach provides better predictions of maximum stable droplet diameter and Sauter mean diameter compared to existing simple empirical correlations including Boll, Nukiyama and Tanasawa. For more practical purpose, we developed the simple, one dimensional (1-D) calculation of Sauter mean diameter.

• 대한수의학회지
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• 제36권4호
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• pp.929-939
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• 1996

The present study was undertaken to establish a relationship between bovine follicle size and oocyte diameter, compare the nuclear maturation competence of oocytes of different diameter groups and the nuclear maturation changes in Korean Native Cattle according to in vitro maturation period. To compare the relationship between follicle size and oocyte diameter, follicles were dissected, measured, and assigned to one of the following size categories($4{\geq}mm$, 3-4mm, 2-3mm, 1-2mm, and < 1mm), investigate the maturation competence in the different-sized oocytes, which were divided into three groups( < $110{\mu}m$, 110 - < $120{\mu}m$, and ${\geq}120{\mu}m$). Oocytes were cultured in the culture medium during 0, 6, 12, 18, and 24hrs, respectively, stained, and measured the nuclear maturation degree according to period. When compared the relationship between follicle size and intrafollicular oocyte diameter, oocyte diameters of three groups of ${\geq}3mm$ follicle-sized were significantly higher than < 3mm (p<0.01). After in vitro maturation, the rates reached to MI stage of < $110{\mu}m$ oocyte groups(25%) was higher than $110-120{\mu}m$ and ${\geq}120{\mu}m$ oocyte groups(11 and 10%) reached to the same stage(p<0.01), and the rates throughout MII stage of $110-120{\mu}m$ and ${\geq}120{\mu}m$ and < $110{\mu}m$(70 and 76%) groups were higher than < $110{\mu}m$(35%)(p<0.01). When nuclear maturation rates were measured according to period, < 6hr groups(7 and 10%) showed lower rates reached to MI than ${\geq}12hr$ groups(100%), 24hr groups(76%) revealed higher rates throughout MII than 18hr groups(40%). These results indicate that the preparation of oocyte for the production of in vitro fertilization embryos and nuclear transplantation ones could be adapted, as follicle increased up to appointed size there was a corresponding increase in oocyte diameter, and differences of nuclear maturation rate revealed according to oocyte diameter and maturation period.

• 한국생산제조학회지
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• 제21권3호
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• pp.415-420
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• 2012

Dust collecting performance of axial-vane type cyclone for oil mist was analyzed in this study. For predicting cut diameter size of cyclone, the number and angle of vane (${\beta}_2{^{\prime}}$) was calculated by CFD. As the result, ${\beta}_2{^{\prime}}$ was decreased as the number of vane was increased and the angle of inclination (${\beta}_2{^{\prime}}$) decreased, and it cause strong swirl flow. Therefore, it could be confirmed that as the number of vane was increased and the angle of inclination was decreased, cut diameter size was decreased. Also, by verifying the results of CFD through experiment, the cut diameter size could be 2 ${\mu}m$ at 4 $m^3/min$ of flow rate.

• Journal of Advanced Marine Engineering and Technology
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• 제18권4호
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• pp.43-52
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• 1994

I investigated experomentally the spray characteristics to the operating conditions and the shapes of internal mixing twin fluid atomizer. The wide variations of air per liquid ratio are conducted to predit the influences of the Sauter mean diameter(SMD), spray angle, distribution of drop size, the flowing condition of gas and length, flowing, area of gas and liquid, and diameter, number and place of the orifice. In this experiment, air per liquid raio, mixing chamber length per diameter, orifice diameter, and the flowing area ratio of gas and fluid influences greatly on SMD, spray angle, distribution of drop size and intermittent fluctuation region.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2002년도 International Meeting on Information Display
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• pp.674-677
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• 2002

Vertically aligned CNTs were grown on Fe-deposited $SiO_2$ substrates using thermal CVD of acetylene gas. The size of Fe particle is controlled by the flow rate of $NH_3$ and pretreatment time, which leads to control the diameter of CNTs. As the diameter of CNTs decreases, the growth rate is enhanced with an inverse dependence of the CNT diameter. The growth rate of CNTs increases linearly as the growth time increases until 30 min but is rapidly decreased over 40 min. We found an inverse relation between the diameter and growth rate of carbon nanotubes. As the diameter of CNTs increases, the compartment layers of bamboo-shaped CNTs appear more frequently. A base-growth model is suitable to explain the dependence of growth rate and structure of CNTs on the diameter size of catalytic particles.

• 대한수의학회지
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• 제6권1호
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• pp.82-91
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• 1966

Studies On the myelinated fibers of the recurrent laryneal nerves were made in five, species of domestic animals namely dog, pig, goat, horse and Korean ox. Throughout the studies, the following characteristics of the myelinated fibers were obtained. 1. The number, size and cross sectional area of the myelinated fibers seemed to be proportionally related to the animal body weights. 2. The highest peak of diameter size frequency distribution of the myelinated fibers, observed at the right cranial level, in dog, goat and horse were 4-6 micron group, while in the case of Korean ox, 10-12 micron group was the highest. 3. The highest peak of diameter size frequency distribution of the myelinated fibers, observed at the right caudal level of Korean ox was 6-8 micron group, and 4-6 micron group was the highest in the other animals. 4. The highest peak of diameter size frequency distribution of the myelinated fibers obsered at the left cranial level was same to that of right cranial level. 5. The highest peak of diameter size frequency distribution of the myelinated fibers, observed at the left caudal levels in dog, goat, horse and Korean ox was 4-6 micron group, while in case of pig, $14-16{\mu}$ group was the highest. 6. The largest cross sectional areas were found in the group of 10-16 micron in all species of animals. 7. The fiber diameter size frequency distribution of recurrent laryngeal nerves of dog, goat, pig and horse were bimodal and Korean ox seemed to be a unimodal.

• 한국자동차공학회논문집
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• 제9권5호
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• pp.75-81
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• 2001

This paper presents the atomization characteristics of single hole injector in the direct injection type diesel engine. The spray characteristics of fuel injector such as the droplet size and velocity were measured by phase Doppler particle analyzer. In this paper, the atomization characteristics of fuel spray are investigated for the experimental analysis of the measuring data by the results of mean diameter and mean velocity of droplet. The effect of fuel injection pressure on the droplet size shows that the higher injection pressure results in the decrease of mean droplet diameter in the fuel spray. The minimum size of fuel spray droplet appears on the location of 40mm axial distance from nozzle exit of diesel injector. Based on the experimental results, the correlation between the droplet diameter and mean velocity of the diesel spray due to the change of axial and radial distance from the nozzle tip were investigated.

• Journal of Chest Surgery
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• 제21권6호
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• pp.984-989
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• 1988

2-D echocardiographic examination of the aortic root diameter was known to be useful in the selection of the size of the prosthetic valve. Valve-patient mismatch was occasionally a serious problem after valve replacement, especially in aortic valve disease. Preoperative knowledge of the patient`s valve annulus size is therefore of great importance in the surgical management of these patients. So the relationship between preoperative 2-D echocardiographic diameter of the annulus size and replaced prosthetic valve were evaluated. 13 patients were analyzed in this study. 2-D echocardiographic measurements of aortic annulus diameter, as determined from the parasternal long axis view and apical four chamber view, demonstrated a high correlation with actual prosthetic valve size implanted at surgery[r=0.86, p< 0.001, SEE=1.08].

• 대한견주관절학회:학술대회논문집
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• 대한견주관절학회 2009년도 제17차 학술대회
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• pp.204-204
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• 2009