• Nuclear Engineering and Technology
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• v.25 no.3
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• pp.381-393
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• 1993

This paper presents the experimental results on flooding of countercurrent flow in vertical multirod channels, which consists of falling water film and upward air flow. In particular, the effects of spacer grids, with and without mixing vane, and of blockage in the multirod bundle on the behaviour of flooding were investigated. The 5$\times$5 zircaloy tube bundle was used for the test section. The comparison of previous analytical models and empirical correlations with present data on flooding showed that the existing models and correlations predict much higher flooding curves. The spacer grid causes the lower flooding air flow rate to compare with the bare rod bundle. However, the mixing spacer grids need a higher flooding air flow rate for a constant liquid flow rate than the spacer grids without mixing vanes. The bundle containing blockages has the highest flooding air flow rate among the bundles with spacer grids and blockages. Empirical flooding correlations for the three types of test section have been made.

• Journal of the Korean Ceramic Society
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• v.44 no.7
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• pp.362-367
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• 2007

Stent is a tiny structure made with either ceramic coating and/or bare metal. Being approximately $1{\sim}2 mm$ in diameter, it consists of holes, slots, or void space and is designed to cover entire medical lesions. Stent implantation into patients' arteries has been practiced for a little more than a decade in order to widen the blocked artery. The adoption of the stent has significantly improved the efficacy when compared with the previous medical practice by balloon angioplasty alone. Yet better biomedical performance of the stent is being demanded in order to eliminate the still existing problem of artery restenosis, which means the artery becomes narrowed again. Recent literature survey shows researches on ceramic coatings onto the stent surface, or material design to improve the mechanical response of the stent. This study focuses more on the material design and mechanical analysis. The results showed that the void configuration within the stent affects the mechanical response significantly. The rectangular shape was found to yield expansion at a relatively lower pressure than the elliptical slot for a slotted tube stent. The present results, when combined with research on coating at the stent surface, may provide stents with improved bio-medical performance.

• Journal of Fashion Business
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• v.17 no.2
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• pp.46-62
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• 2013

This thesis aims to provide basic resources for the development of various uniform designs of cheerleaders by investigating the currently favoured uniform designs. The 13 professional cheerleader teams were existed among the 25 professional sports teams-9 baseball, 10 basketball and 6 volleyball teams. In each sports teams, four cheerleader's uniform were chosen and evaluated in terms of the cheerleader uniform design by analyzing the forms, colors, decorations and accessories. The result shows that the common kinds of design representing the symbolic color and the emblem were generally prevalent, instead of particular types of uniform design and subject in accordance with different kinds of the professional baseball, basketball and volleyball respectively. Throughout all the kinds of the sports, the combination of the sleeveless top and hot-pants were most frequently observed. In case of the skirts, the mini flare, wrap, and pleats skirts were the most prevalent, because it gave free to motion for cheerleading. The one-piece style were rather infrequent, comparing with the two-pieces, with the hourglass and fitted silhouette the most frequent type, and all those were mini in length. The sleeve in top were generally absent or short, however the bare top style was never found that the top would have a risk of being taken off downwardly during cheerleading. The accessories and the cheering tools were not so much used. The cap and headdresses were not many in kinds. The pompom, megaphone, tube stick, towel, umbrella and musical instruments would not be sufficient to play a role of tools for cheering, which suggests that the rather advanced tools or instruments for cheering in the sports need to be developed, not alone the uniform design.

• Journal of Electrochemical Science and Technology
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• v.12 no.3
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• pp.330-338
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• 2021

An integral electrode-bipolar plate assembly, which is composed of electrode, conductive adhesive film (CAF) and bipolar plate, has been developed and evaluated for application with a vanadium redox flow battery (VRB) to decrease contact resistance between electrode and bipolar plate. The CAF, made of EVA (ethylene-vinyl-acetate) material with carbon black or CNT (Carbon Nano Tube), is applied between the electrode and the bipolar plate to enable an integral assembly by adhesion. In order to evaluate the integral assembly of VRB by adhesive film, the resistivity of integral assembly and the performance of single cell were investigated. Thus, it was verified that the integral assembly is applicable to redox flow battery. Through resistance and contact resistance of bare EVA and CAF films on bipolar plate were changed. Among the adhesive films, CAF film coated with carbon black showed the lowest value in through resistance, and CAF film coated with CNT showed the lowest value in contact resistance, respectively. The efficiency of VRB single cell was improved by applying CAF films coated with carbon black and CNT, resulting in the reduced overvoltage in charging process. Therefore, the energy efficiency of both CAF films, about 84%, were improved than that of blank cell, about 79.5 % under current density at 40 mA cm^-2. The energy efficiency of the two cells were similar, but carbon black coated CAF improved the coulomb efficiency and CNT coated CAF improved the voltage efficiency, respectively.

• Korean Journal of Soil Science and Fertilizer
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• v.29 no.4
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• pp.353-359
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• 1996

Micro plot study was conducted to elucidate the behavior of nitrogen derived from animal manure in soil and to obtain the fundamental information on animal waste management. Soils used in this experiment were sandy loam and loam. Soil water samplers (1m length ceramic cup tube) were installed at 90cm depth of soil to collect the percolate. Fresh and fermented pig manure were applied at the rate of 0, 50, 100 ton per ha. Maize was grown to evaluate the effect of crop on nitrogen behavior through soil profile. Concentration of nitrate nitrogen in percolate increased by application of pig manure. This trend was more obvious at the loam with fermented pig manure than sandy loam with fresh pig manure treatment. The concentration of nitrate nitrogen was lower under the maize cultivation than bare soil condition by 64.6-68.9%. Concentration of Ca, Mg and Na of soil and percolate increased as nitrate nitrogen concentration increased. The equivalent ratio of cation to nitrate nitrogen of percolate was increased by application of pig manure. This result showed that canon leaching was accompanied by nitrate nitrogen. Concentration of nitrate nitrogen of subsurface soil was increased by pig manure application.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.2
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• pp.101-108
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• 2009

A fretting wear test rig for dry ambient condition, which employs a piezoelectric actuator, has been developed. It is driven and loaded in a very simple manner with acceptable experimental accuracy. By using the rig, Inconel 690 tube has been tested under the normal load of 10 and 15N with sliding amplitude of less than $100{\mu}m$ during $10^6$cycles. The wear resistance of the material has been characterized in terms of the wear coefficient based on the work rate model. SEM micrographs show the complex structures of the scars, which consist of risen peaks, plate-type thin layers and locally exposed bare surfaces. The cracks spread over the layers give clue to the fretting wear mechanism of the material.

• Journal of Bio-Environment Control
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• v.28 no.3
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• pp.204-211
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• 2019

The purpose of this study is to provide basic data for setting environmental design standards for domestic greenhouses. We conducted experiments on thermal environment measurement at two commercial greenhouses where hot water heating system is adopted. We analyzed heat transfer characteristics of hot water heating pipes and heat emission per unit length of heating pipes was presented. The average air temperature in two greenhouses was controlled to $16.3^{\circ}C$ and $14.6^{\circ}C$ during the experiment, respectively. The average water temperature in heating pipes was $52.3^{\circ}C$ and $45.0^{\circ}C$, respectively. Experimental results showed that natural convection heat transfer coefficient of heating pipe surface was in the range of $5.71{\sim}7.49W/m^2^{\circ}C$. When the flow rate in heating pipe was 0.5m/s or more, temperature difference between hot water and pipe surface was not large. Based on this, overall heat transfer coefficient of heating pipe was derived as form of laminar natural convection heat transfer coefficient in the horizontal cylinder. By modifying the equation of overall heat transfer coefficient, a formula for calculating the heat emission per unit length of hot water heating pipe was developed, which uses pipe size and temperature difference between hot water and indoor air as input variables. The results of this study were compared with domestic and foreign data, and it was found to be closest to JGHA data. The data of NAAS, BALLS and ASHRAE were judged to be too large. Therefore, in order to set up environmental design standards for domestic greenhouses, it is necessary to fully examine those data through further experiments.

• Journal of the Korean Society of Radiology
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• v.81 no.5
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• pp.1175-1183
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• 2020

Purpose To evaluate the technical feasibility and clinical efficacy of percutaneous transgastric stent placement after the failure of treatment attempt with the transoral approach in malignant gastroduodenal obstruction patients. Materials and Methods From October 2008 to April 2016, nine patients (M:F = 4:5; mean age = 66 years) with malignant gastroduodenal obstruction underwent stent placement via a gastrostomy tract, which was attributed to the failure of the transoral approach. The primary etiologies of the obstruction were pancreatic (n = 5), gastric (n = 2), and metastatic (n = 2) cancers. Through percutaneous gastrostomy, dual stents (inner bare metal and outer polytetrafluoroethylene-covered) were deployed at the obstruction site. The technical and clinical success rates, as well as complications were evaluated during the follow-up period. Results Stents were successfully inserted in eight patients (88%). We failed to insert stent in one patient due to the presence of a tight obstruction. After stent placement, symptoms improved in seven patients. Gastrostomy tube was removed 9 to 20 days (mean = 12 days) after the stent insertion. During the mean follow-up of 136 days (range, 3-387 days), one patient developed a recurrent symptom due to tumor overgrowth. However, there were no other major complications associated with the procedure. Conclusion Percutaneous transgastric stent placement appeared to be technically feasible and clinically effective in patients who underwent a failed transoral approach.