• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.3
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• pp.538-546
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• 1989

Effect of liquid viscosity was studied experimentally on the drop size distributions of the liquid sprays from swirl atomizers. Glycerine-Water mixtures were used as test fluids for the experiments. Drop sizes of the liquid sprays were measured with the light scattering method. The concept of the standard deviation was introduced to represent the degree of uniformity of the drop size distributions. Experimental results show that the spray drops become coarser and less uniform with the liquid of higher viscosity. The effect of viscosity on the Sauter mean diameter and the standard deviation appeared to be more significant with the lower injection pressure. It was also confirmed that the Sauter mean diameter increases with the increase of the liquid viscosity and with the decrease of the injection pressure.

• Animal cells and systems
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• v.1 no.2
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• pp.341-344
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• 1997

Receptor-mediated endocytosis has been suggested for a stage-specific transport mechanism of vitellogenin into the oocytes of a sabellid poly chaete, Pseudopotamilla occelata. Membrane proteins of oocytes of three size classes, including small (30-70 $\mu\textrm{m}$ in diameter), intermediate (70-140 $\mu\textrm{m}$ in diameter) and large (180-200 $\mu\textrm{m}$ in diameter), showed a atage-specific variation. Coelomic fluid proteins (CP), ass$\mu\textrm{m}$ed to be vitellogenin, consists of several proteins, which showed quite a different pattern from that of yolk proteins. Incorporation of $^{125}I$-CP into the oocytes of the intermediate size class almost linearly increases with time, showing a contrast to the pattern of the large size class, in which the incorporation is low and approaches a plateau, suggesting the vitellogenin transports by a regulated process only in the intermediate size class. Vitellogenin receptor proteins were identified to be 60 kDa and 68 kDa only in the intermediate size class by a ligand blotting test.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.3
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• pp.662-669
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• 1994

In the combustion system, the optimum spray conditions reduce the pollutant emission of exhaust gas and enhance the fuel efficiency. The spray characteristics-the drop size, the drop velocity, the number density and the mass flux, become increasingly important in the design of combustor and in testifying numerical simulation of spray flow in the combustor. The purposes of this study are to clarify the spray characteristics of twin-fluid nozzle and to offer the data for combustor design and the numerical simulation of a spray flow. Spatial drop diameter was measured by immersion sampling method. The mean diameter, size distribution and uniformity of drop were analyzed with variations of air/liquid mass flow ratio. The results show that the SMD increases with the liquid supply flow rate and decreases with the air supply velocity. The radial distribution of SMD shows the larger drops can diffuse farther to the boundary of spray. And the drop size range is found to be wider close to the spray boundary where the maximum SMD locates.

• The korean journal of orthodontics
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• v.22 no.1
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• pp.135-146
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• 1992

It was the purpose of this study to analyze and compare the mechanical properties of ortho dontic open coil springs. Four variable factors were presented - wire diameter (.008", .009", .010"), lumen size (.030", .032", .036"), arch wire size and shape (.016" round, $ .016^{{\prime}{\prime}}{\times}.022^{{\prime}{\prime}}$ rect.) and alloy type (HiT II, Elgiloy, Sentalloy). The total 104 specimens were divided into 13 groups, and compression test was performed on an Instron test machine. The load deflection curve of each open coil spring was obtained, from which, the load-deflection relations, stiffnesses, percent recoveries were computed statistically. The results were obtained as follows: 1. When the lumen size of the coil spring remained constant, stiffness and percent recovery increased as the wire diameter increased. 2. When the wire diameter of the coil spring remained constant, stiffness and percent recovery decreased as the lumen size increased. 3. The effect of size and shape of arch wire on the coil spring was not statistically significant. 4. In alloy types, stiffness was the greatest in HiT II (55.21), Elgiloy (42.61) and Sentalloy (7.74) in that order. Sentalloy exhibited superior percent recovery and long range of action.

• Transactions of the Korean Society of Automotive Engineers
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• v.2 no.4
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• pp.39-49
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• 1994

An experimental investigation was undertaken in a diesel spray to evaluate wall impingement behavior and droplet size distribution. Emphasis is placed on the possibility of the application for new combustion type which is based on OSKA-D type. Visualization were employed using optical scheme which was a spark shadowgraphy to observe the behavior of wall impingement caused by diesel spray vertically injected at the center of the combustion chamber. Droplet size measurements using Malvern system were made to quantify the visual observations with surface diameter of impingement. The effects of the surface dia. variation on the droplet size during injection with the wall impingement spray are discussed. It was found that for the wall impingement spray the droplet size becomes greatly small rather than the spray without the wall impingement and the droplet deposition rate of the injection fuel is decreased as the surface area of impingement becomes small.

• Proceedings of the SAREK Conference
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• 2005.11a
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• pp.161-166
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• 2005

The objectives of this paper are to estimate the ground thermal conductivity by ground heat exchangers in two different places - Chooncheon and Wonjoo, and to analyze the effect of ground thermal conductivity on the ground thermal diffusivity and the size of the ground heat exchanger. In Chooncheon area, a single-U type HDPE pipe (25mm diameter) with borehole diameter of 150mm, length of 150m is installed. In Wonjoo area, a single-U type HDPE pipe (40mm diameter) with borehole diameter 150mm, length of 200m is installed. It is found that the ground thermal conductivities are estimated as 2.69 $W/m^{\circ}C$ and 2.99 $W/m^{\circ}C$ in Chooncheon and Wonjoo, respectively. It is also found that the ground heat exchanger size is reduced by 8.6% with 25% increase of ground thermal conductivity, and increase by 11.8% with 25% decrease of ground thermal conductivity.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.11a
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• pp.145-146
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• 2023

One of the causes of recent construction site collapses was that the compressive strength of concrete was less than half of the allowable design standard strength range. In the safety diagnosis of structures, the compressive strength of concrete is a factor that determines the durability of a building. Therefore, in this study, we aim to examine the characteristics of compressive strength according to the particle size distribution of coarse aggregate among the compressive strength factors using small-diameter cores. To avoid problems when collecting cores, core specimens with diameters of 100×200, 50×100, and 25×50 (mm) were manufactured directly. As a result of measuring the compressive strength of concrete for each diameter, the larger the core diameter, the higher the compressive strength. has increased.

• 한국연소학회:학술대회논문집
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• 2006.04a
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• pp.189-193
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• 2006

Experiments were performed to investigate the melting characteristics of pellet fuel made of LDPE and PP for a waste plastic firing boiler. Pellet fuel in a burner goes through conduction, convection and radiation transferred from flame in a furnace, and complex thermo/chemical processes. To figure out effects of ambient temperature and size of pellet on melting time pellets with a diameter from 5 mm to 40 mm were made to contact high temperature flue gas generated by a LNG firing pilot burner. Though melting processes of plastics include complicated heat transfer in a burner, parameters are limited to flue gas temperature and size for the simplicity in this study. From the results, melting times of LDPE and PP with a diameter of 5mm are 63 and 62 secs respectively at 600 $^{\circ}C$ while 677 and 583 sees respectively for a diameter of 40 mm. At $900^{\circ}C$, melting times of LDPE and PP with a diameter of 5mm are 21 and 24 sees respectively while 408 and 337 secs respectively for a diameter of 40 mm. It is found that melting time of LDPE is longer than that of PP, and melting times of both in general increase with diameter of pellets. It is thought melting is dependent mostly on melting temperature of plastic. It is expected melting times obtained from the study might be taken into account in designing a pellet firing burner for a boiler

• Development and Reproduction
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• v.25 no.2
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• pp.75-82
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• 2021

We studied steroid metabolites produced from red-spotted grouper ovarian follicles during maturation. Oocytes with 350-500 ㎛ diameter were in vitro incubated in the presence of [³H] 17α-hydroxyprogesterone as a precursor. Steroid metabolites were extracted from incubated media and oocytes. The extracts were separated and identified using thin layer chromatography, high performance liquid chromatography and gas chromatography-mass spectrometry. The identified metabolites were androstenedione (A₄), testosterone (T) and estrone (E₁). The metabolites of A₄ was dominant in all size of oocytes and it was the highest in 480 ㎛ diameter oocytes. The metabolites of two progestins, 17α,20β-dihydroxy-4-pregnen-3-one and 17α,20α-dihydroxy-4-pregnen-3-one were detected in the oocytes less than 480 ㎛ diameter although they were not identified definitely. In the oocytes of 480 ㎛ diameter, metabolite of progestin was the highest, and germinal vesicle (GV) was still in the middle of cytoplasm. In the oocytes of 500 ㎛ diameter, GV was began to migrate and the major metabolites were A₄ and E₁. The metabolite of E₁ was detected in all size of oocytes and it was higher than that of E₂. These results suggest that oocytes of 480 ㎛ diameter are the transitional stage involving steroidogenic shift to final oocyte maturation and potential function of E₁ during maturation process.

• Asian-Australasian Journal of Animal Sciences
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• v.11 no.3
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• pp.293-299
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• 1998

This study was undertaken to measure the concentrations of estradiol-$17{\beta}$, progesterone and testosterone, and to study their relationship with each other and with follicular size in individual buffalo ovarian follicles categorized as small (4 to 5 mm diameter), medium (6 to 9 mm diameter) and large (${\geq}10mm$ diameter). Steroid hormone concentrations varied markedly within follicles of each size category. Estradiol-$17{\beta}$ concentrations (pmol/ml) were positively related to follicular diameter (R = 0.34, n = 308, p < 0.001) and were significantly higher (p < 0.001) in large (1$118.46{\pm}30.25$), compared to those in medium follicles ($50.32{\pm}8.29$) which, in turn were significantly higher (p < 0.001) than those in small follicles ($19.70{\pm}$5.57). Progesterone and testosterone concentrations (pmol/ml) were not related to follicular diameter and were not different among small ($330.99{\pm}27.32$ and $17.68{\pm}2.44$ respectively), medium ($384.84{\pm}26.20$ and $36.47{\pm}4.55$, respectively) and large follicles ($253.25{\pm}32.23$ and $22.57{\pm}4.48$, respectively). Estradiol-$17{\beta}$ and progesterone concentrations were positively related (R = 0.39, n = 47, p < 0.01) in small, unrelated in medium and negatively related in large follicles (R = -0.59, n = 23, p < 0.01). There was no relationship between estradiol-$17{\beta}$ and testosterone concentrations in follicles of all the three size categories. Progesterone and testosterone concentrations were positively related in large follicles (R = 0.57, n = 18, p < 0.02). There was no relationship between the two hormones in small and medium sized follicles. When the follicles with estradiol-$17{\beta}$/progesterone molar ratios of > 1.00 were considered non-atretic, and the rest at different stages of atresia, 197/208(95%) follicles were found to be atretic.