• Proceedings of the Korea Concrete Institute Conference
• /
• 2001.05a
• /
• pp.763-768
• /
• 2001

The purpose of this study is to research a specific material characteristics of top down concrete at column joint and to reduce column joint opening. Based on the established top down study, the experiment to apply an real construction case is performed. When the concrete placed into joint of top down column, raised air bubble is left as opening. This study is examined the incomplete packing reason in the top down column and found to air deflation method. The result of study is below (1) As the method to minimize column opening caused from confined air, it is required that an air exhaust port installation in joint column. (2) From air exhaust port installation, most of air bubble in column part is exhausted. As the concrete placing height is going up, air bubble size is going smaller.

• Journal of Ocean Engineering and Technology
• /
• v.10 no.2
• /
• pp.136-145
• /
• 1996

The theory is based on two thermodynamic equations for the air mass in the air column and bydrodynamic equation for the relation between the response of the air in the water column and the incident wave. The numerical model is experimented in a two dimensional water tank and the caisson model with sloped front wall is tested in the large towing tank.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2005.05a
• /
• pp.468-472
• /
• 2005

In this paper, the static and dynamic stiffness of the air bearing stage for micro-micro machine tool are examined experimentally. For stiffness and precision concerns, air bearing stages are adapted for 3-axis micro-milling machine which is size of $200x200\;mm^2$. The air bearings in the stage are preloaded by permanent magnets to achieve desired bearing clearance and stiffness for vertical direction. As the stiffness of the air bearing is primary interests, static stiffness test were performed on XY stage in Z direction and Z column in Y direction. Dynamic test were performed on XY stage and Z column, respectively. Both static and dynamic tests were performed in different air pressure conditions. The vertical stiffness of XY stage is about 9 N/ pm where Y stiffness of Z column is much smaller as $1\;N/{\mu}m$ because of the large moment generated by Y force on the column.

• KSBB Journal
• /
• v.18 no.6
• /
• pp.455-460
• /
• 2003

This study was designed to find out the rapid fermentation of soy sauce from koji hydrolyzates using air bubble column reactor packed with coimmobilized mixed culture system. Continuous ripid production was performed by coimmobilized Z. rouxiii BH-90 and C. versatilis BH-91. Coimmobilized cells of Zygosaccharomyces rouxii BH-90 and Candida versatilis BH-91 mixture cells in the column reactor produced 2.8％ ethyl alcohol and 18mg/L 4-ethylguaiacol over 96 hours under the optimal conditions. Coimmobilized cells produced 2.30∼2.4% ethyl alcohol during 30 days, and decreased gradually from 40 days to 70 days. Also coimmobilized cells produced 4-ethylguaiacol at the constant rate of 16∼18mg/L and decreased gradually after 40 days. Final product of soy sauce contained 2.4% ethyl alcohol and 18mg/L 4-ethylguaiacol. However, amino acid compositions of soy sauce were consisted of predominantly glutamic acid, leucin, arginine, aspartic acid, Iysine and valine, which were more than 50% of total amino acid.

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

• 한국태양에너지학회:학술대회논문집
• /
• 2009.04a
• /
• pp.155-161
• /
• 2009

Desiccant systems have been proposed as energy saving alternatives to vapor compression air conditioning for handling the latent load. Use of liquid desiccants offers several design and performance advantages over solid desiccants, especially when solar energy is used for regeneration. The liquid desiccants contact the gas inside the packed column and the heat transfer and mass transfer will occur. This proposal is try study the mass transfer and heat transfer inside the packed column of dehumidifier and regenerator systems. And later on, the rates of dehumidification and regeneration that were affected by desiccant flow rates, air temperature and humidity, and desiccant temperature and all that variation will influence the performance of the systems.

• Progress in Superconductivity and Cryogenics
• /
• v.4 no.1
• /
• pp.145-150
• /
• 2002

The distillation column is one of large energy consumable units in the cryogenic air separation process and the accurate energy analysis of this unit is necessary for choice of energy saving process. In this work, the energy method was adopted for energy analysis of a cryogenic nitrogen distillation column. In order to designing the energy saving distillation column, the exergy distribution of feed air, exergy efficiency and exergy loss for process condition was investigated and the optimal process condition to minimize the exergy loss was found. The result from this work can be used as a guideline for the choice of the process design conditions and efficiency improvement of cryogenic distillation column.

• Journal of Ocean Engineering and Technology
• /
• v.23 no.5
• /
• pp.15-24
• /
• 2009

The results of a simulation study of variable liquid column oscillations in U-tanks with a novel control scheme are presented. The configuration under investigation is analogous to that of the tuned liquid-column damper used to suppress oscillatory motion in large structures like tall buildings and cargo ships. However, by virtue of an adequate controller, the response of amplitude of the U-tanks becomes larger in a desired frequency range. The motion of wave energy conversion system equipped with a variable liquid column oscillator is described by a series of nonlinear differential equations. The equations describe the motion of body under ocean wave excitation, and the motion of liquid with an air-spring effect caused by the compression and expansion of air in vertical liquid columns and air chambers. It is shown that the effect of the air-spring has a vital role to maintain the natural frequency of oscillation in the system to synchronize with the frequency of the ocean wave, thus the system provides the most effective mode for energy extraction from the ocean.

• Economic and Environmental Geology
• /
• v.35 no.5
• /
• pp.421-428
• /
• 2002

Lab-scale experiments were conducted to evaluate the effect of surface tension reduction on the extension of the influence zone and the VOC removal efficiency of ground water sparging. A glass column packed with coarse sand was used for VOC removal test at two different surface tensions. A glass column without porous media was also used fer control purpose prior to sand-packed column test. A quasi-two-dimensional glass box model, packed with a sand, was used fer sparging zone tests at different water surface tensions. Surface tension of the aquoues solution used in this study was controlled using sodium dodecyl sulfate (SDS). For the glass, sand column experiments, total amount of air filled in the media increased as surface tension decreased. Toluene (used as VOC in this study) removal rate increased slightly with decreased surface tension f3r both free water column and sand-packed column. Air sparging zone extended up to 500% as the surface tension decreased. Combining the results from two different experiments, VOC removal efficiency is expected to increase significantly with surface tension reduction.

• Toxicological Research
• /
• v.5 no.2
• /
• pp.97-104
• /
• 1989

A new exposure system was developed to generate p-dinitrobenzene (p-DNB) containing atmosphere. A glass column was filled with small glass beads coated with the chemical. The p-DNB containing medium was heated to a temperature beyond the boiling point of p-DNB. A stream of air flow was forced to pass through the column and let it mixed with fresh air before introducing into an inhalation chamber. The concentration of p-DNB in the chamber air was measured by direct assaying the air directly and by sampling the chemical using a microfilter installed in the chamber.