• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.26 no.2
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• pp.127-129
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• 2015

Background and Objectives : The etiology of globus pharyngeus remains uncertain. It has been known there is a relationship between the presence of air bubbles in esophagus and GERD symptoms. The aim of this study is to identify relationship between the globus symptom and the presence of air column in esophagus. Subjects and Methods : The study population consisted of 46 patients who underwent CT scan as part of evaluation for globus. Controls were chosen from the population consisted of patients with lymphadenopathy who underwent CT scan. The correlation between the presence of globus symptom and diameter, volume, and position of the air column was assessed using t-test. Reproducibility of diameter and volume of the esophageal air column was analyzed using intraclass correlation coefficient. Results : In study group, the mean volume of the air column was $769.56{\pm}983.08mm^3$, the mean diameter was $8.24{\pm}4.90mm$, the mean distance from the inferior border of posterior lamina of cricoid cartilage was $88.86{\pm}28.01mm$. In control group, $682.18{\pm}767.28mm^3$, $8.37{\pm}5.50mm$, $88.34{\pm}21.06mm$, respectively. There were no differences of diameter, volume and distance of the air column between the two groups. We failed to obtain acceptable reliability when we compare the diameter and the volume of the esophageal air column. Conclusion : There was no relationship between air column of esophagus and presence of globus symptom. And the measurement of diameter and volume of the esophageal air column change over time and it should be considered in a further study.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.2
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• pp.250-258
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• 2010

A numerical analysis of reactive flow in a liftoff flame is accomplished to elucidate the characteristics of flame propagation velocity and volume integral of reaction rate with the variation of nozzle diameter and fuel injection flow rate in a liftoff flame consisted with fuel rich region, fuel lean region and diffusion flame region. The increase of fuel injection velocity enhances flame propagation velocity for the selected three nozzle diameter(d=0.25, 0.30, 0.35mm), but its effect on the flame propagation velocity is not much greater than 4.3%. The increase of fuel flow rate is directly and linearly related with the volume reaction rate and so the volume reaction rate, not the flame propagation velocity, might be considered to accommodate the variation of fuel flow rate in a liftoff flame.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.1 s.256
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• pp.11-17
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• 2007

In this paper, we present a design, analysis, fabrication and performance test of the novel DoD metal-jet system for application to the high-density and high-temperature-melting materials. The theoretical analysis of the metal-jet nozzle system is derived by using electro-mechanical analogy. Based on the theoretical analysis results, we design the metal-jet print head system and fabricate the metal-jet system, which can eject the droplet of lead-free metal solder in high-temperature. In the experimental test, we set up the test apparatus for visualization of the droplet ejection and measure the ejected droplet volume and velocity. As a result, the diameter, volume and the velocity of the ejected droplet are about 65 $\mu$m $\sim$ 70 $\mu$m, 145p1 $\sim$ 180 pl and 4m/s, which shows quite good agreement with the theoretical analysis results of the 75 $\mu$m-diameter and 220 pl-volume of droplet. In comparison with the experimental result, the errors of diameter and volume are 7% $\sim$ 13% and 18 $\sim$ 34%, respectively.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.4
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• pp.564-573
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• 2001

The mechanical properties of short carbon/glass fiber reinforced polypropylene are experimentally measured as functions of fiber content and nozzle diameter. Also, these properties are compared with the survival rate of reinforced fibers and fiber volume fraction using image analysis after pyrolytic decomposition. The survival rate of fiber aspect ratio as well as fiber volume fraction is influenced by injection processing condition, the used materials and mold conditions such as diameter of nozzle, etc. In this study, the survival rate of fiber aspect ratio is investigated by nozzle size variations in injection/mold sides. It is found that the survival rate of glass fiber is higher that the survival rate of glass fiber is higher than that of carbon fiber. Both tensile modulus and strength of short-fiber reinforced polypropylene are improved s the fiber volume fraction and nozzle diameter are increased.

• Journal of KSNVE
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• v.9 no.2
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• pp.285-294
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• 1999

Transient analysis for compressible fluid flow has been performed experimentally and analytically to study the dynamic characteristics of the end volume transmission lines following a sudden pressure change a its entrance. The numerical method was developed based on the method of characteristics. The sudden pressure at its entrance was generated by rupture of diaphragm in a shock tube. The sudden pressure was used to obtain the response, as input signal for the numerical analysis. The response to the sudden pressure at the end volume was measured using a pressure transducer. The experimental result shows good agreements with the numerical result. The effects of tube length, its diameter and end volume magnitude are evaluated on the responses of the pressure and on the damping factor. It is found that the viscous damping effects on the response through the transmission pipeline becomes larger with increasing pi;eline length and decreasing diameter of the pipe and the fluid-elastic stiffness decreases with increasing the terminal volume. The numerical approach presented in this paper can be very useful in designing the instrument and control system.

• Journal of the Korean Society of Tobacco Science
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• v.16 no.2
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• pp.181-190
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• 1994

Various active carbons were made from plant sources of coconut shell, pine tree, oak tree and lignite coal. Pore characteristics of these adsorbents were investigated. 1, With increasing activation time, specific surface area and pore volume increased, but the development of micropores was limited at a certain level. The average pore diameter, by BET, of coconut active carbon was 15.5-21.8$\AA$ and that of lignite carbon was 15.6-31.3$\AA$. The pore diameters of silica-gel, sepiolite and zeolite was 30.9$\AA$, 58.6$\AA$ and 55.7$\AA$, respectively. 2. The Horvath - Kawazoe micropore diameter of coconut shell active carbon was under 10.5$\AA$ and that of the other active carbon was under 20.9$\AA$ but silica-gel 33$\AA$, sepiolite 103 $\AA$ and zeolite was unexpectedly large to be 175$\AA$. From the difference between BET micropore diameter and Howath - Kawazoe diameter, it could be said that silica - gel has comparatively uniform pore diameter but sepiolite and zeolite have very uneven diameter. 3. Total pore volume of coconut shell active carbon was 0.27-1.04 cm3/g but that of the other active carbon, 0.23-0.62 cm3/g, was much lower than that of coconut shell active carbon. Hydrophilic adsorbent silica - gel and sepiolite showed big difference in specific surface area, but pore volumes of these were 0.47 and 0.56 cm3/g showing similar value and micropore volumes of these were, respectively, 0.06 cm3/g and 0.04 cm3/g. Total pore volume of zeolite was 0.1 cm3/g and that of micropore was only 0.02 cm3/g.

• Journal of Korean Society of Forest Science
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• v.106 no.4
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• pp.480-486
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• 2017

This study was conducted to develop the merchantable stem volume models to predict the volume up to upper diameter or upper height out of the total stem volume, targeting on Pinus densiflora, Pinus koraiensis, and Larix kaempferi in South Korea. The 131 stemmed sample trees for stem analysis were used as the data for developing the models. The six kinds of merchantable volume equations including merchantable volume ratio form, ratio form, and exponential ratio form were examined to develop the best models. The two models were finally selected as the best models to predict the merchantable volume: $V_d=V_t\{{\exp}[{\alpha}_1(d^{{\alpha}_2}/D^{{\alpha}_3})]\}$ for upper diameter and $V_h=V_t\{1+{\beta}_1(P^{{\beta}_2}/H^{{\beta}_3})\}$ for upper height. By rearranging the best model equations, implicit taper functions were derived, and the estimation was performed for the upper height by upper diameter and upper diameter by upper height. Because of not only the high accuracy but also the convenience, the models developed in this study were considered to be easily applicable in the field of forestry.

• Journal of the Korean Vacuum Society
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• v.2 no.4
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• pp.491-500
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• 1993

The adsorption of nitrogen (77K) and carbon dioxide(273K) was performed on a series of activated carbon fiber. Theadsorption iotherm of nitrogen was typical type 1 and that of carbon dioxide was convex. As the specific surface area increases, there are linear increases in BET constant C mean pore diameter, the width of pore size distribution, wide micropore volume, total micropore volume, total pore volume and external surface area, however, narrow micropore volume was nealy constant . The total micorpore volume fraction in total pore volume is above 97%.

• Geomechanics and Engineering
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• v.2 no.3
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• pp.191-202
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• 2010

The porosity (including the specific surface area and pore volume-diameter distribution) of montmorillonitic soft rock (MSR) was studied experimentally with an electrochemical treatment, based on which the change in porosity was further analyzed from the perspective of its electrokinetic potential (${\zeta}$ potential) and the isoelectric point of the electric double layer on the surface of the soft rock particles. The variation between the ${\zeta}$ potential and porosity was summarized, and used to demonstrate that the properties of softening, degradation in water, swelling, and disintegration of MSR can be modified by electrochemical treatment. The following conclusions were drawn. The specific surface area and total pore volume decreased, whereas the average pore diameter increased after electrochemical modification. The reduction in the specific surface area indicates a reduction in the dispersibility and swelling-shrinking of the clay minerals. After modification, the ${\zeta}$ potential of the soft rock was positive in the anodic zone, there was no isoelectric point, and the rock had lost its properties of softening, degradation in water, swelling, and disintegration. The ${\zeta}$ potential increased in the intermediate and cathodic zones, the isoelectric point was reduced or unchanged, and the rock properties are reduced. When the ${\zeta}$ potential is increased, the specific surface area and the total pore volume were reduced according to the negative exponent law, and the average pore diameter increased according to the exponent law.

• Korean Journal of Plant Tissue Culture
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• v.28 no.6
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• pp.311-315
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• 2001

The relationship among leaf size, leaf protoplast (cell) size, chloroplast size, and chloroplast number were investigated in tobacco and Arabidopsis thaliana at various developmental stages. In tobacco, protoplasts, less than 15.6 ${\mu}{\textrm}{m}$ in diameter had less than 20 chloroplasts, 0.93 ${\mu}{\textrm}{m}$ in thickness and 3.3 ${\mu}{\textrm}{m}$ in length on average. As protoplast size increased from 30 ${\mu}{\textrm}{m}$ to 45 ${\mu}{\textrm}{m}$ in diameter, chloroplast size remained the same (1.57 ${\mu}{\textrm}{m}$ in diameter and 5.55 ${\mu}{\textrm}{m}$ in length on average), but chloroplast number increase from 42 to 101 on average. A similar relationship was also observed in A. thaliana. The ratio of total chloroplast volume to protoplast volume was constant (0.105 in tobacco and 0.325 in A. thaliana) over various developmental stages.