• Korean Journal of Bronchoesophagology
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• v.3 no.1
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• pp.94-100
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• 1997

Background and Objectives : In children with tracheal stenosis, operative management remains a challenging problem due to difficulties of operative techniques and postoperative care. The purpose of this study was to determine the effectiveness of tracheal resection with end to end anastomosis as operative management for tracheal stenosis in children. Materials and Methods : 6 children with severe tracheal stenosis underwent tracheal resection with end to end anastomosis. Causes of stenosis were trauma in 1 case and prolonged intubation or tracheotomy in 5 cases. The diagnoses were made by radiologic evaluation (plain X-ray, CT, 3-Dimensional CT) and confirmed by direct laryngoscopy and ventilating bronchoscopy under general anesthesia. Thyroplasty and unilateral arytenoidectomy were performed in 1 case. Suprahyoid release was done in 1 case with severe adhesion. Decanulation was achieved following postoperative endoscopic examination and pulmonary function test. Postoperative physical and radiologic examinations were given at regular intervals. Results : Stenosis were improved from grade III grade I in 4 cases and from grade II to grade I in 2 cases. Decanulation was achieved on average postoperative 6 months in 5 cases, and 10 years in 1 case due to exertional dyspnea. There were 1 each case of immediate postoperative subcutaneous emphysema, pneumothorax and wound infection. Postoperative granulomas at anastomosis site were treated with laser vaporization under suspension laryngoscope and bronchoscope in 3 cases. There was 1 each case of delayed postoperative vocal cord palsy, aspiration pneumonia and loss of cough reflex. Conclusion In tracheal stenosis of children, tracheal resection with end to end anastomosis has good result with preservation of normal airway. Preoperative evaluation of local factors such as swallowing, vocal cord movement and cough reflex and general condition was important for successful treatment. As the cases in adults, authors considered this operation to be a curable operative management for tracheal stenosis.

• The Journal of the Convergence on Culture Technology
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• v.7 no.2
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• pp.443-451
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• 2021

This study compared and analyzed the thermal characteristics based on the ratio of moisture content of infected and non-infected Bursaphelenchus Xylophilus by heat of combustion experiment. The experiment results are as follows. The analysisresult of the ratio of water content shows that 19.92% on average for infected Bursaphelenchus Xylophilus and 26.27% for non-infected which decreases water content as the size of conduction, convection, and radiant heat increases in case of fire. As the vaporization of the moisture content accelerates, the average moisture content is reached, and the result is contrary to the thermal characteristics of the wood that the moisture content is not ignited by a heat source when the moisture content is under 15%. The combustion heat analysis result showed that infected and non-infected Bursaphelenchus Xylophilus had no significant difference in combustion heat at about 3%. However, it shows that combustion heat is higher than other species. In conclusion, decreasing in moisture content based on the increasing conduction, convection, and radiant heat is one of the direct causes of ignition, and the lower the moisture content, the faster the fire spreads.

• Journal of the Korean Institute of Gas
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• v.23 no.1
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• pp.41-46
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• 2019

LNG is supplying to consumers as gas phase vaporized by major seawater vaporizer, i.e.. open rack vaporizers. But as soon as the temperature of seawater drops below $5^{\circ}C$ in winter, the submerged evaporators should be operated and cause a lot of energy consumption because of their natural gas combustion. In order to reduce the consumption amount, in this study new two-way supplying method of seawater instead of the present one-way supplying system is introduced and analysed the technical possibilities and economical savings. The results showed that in case of the temperature of seawater becomes below $2.5^{\circ}C$, LNG can be evaporated using ORV without operating S MV. If this system is applied in Incheon LNG terminal, the energy saving reaches 11,770 Ton of LNG as 11,760 million won. By the analysis, the two-way supplying system of seawater in ORV can be the most effective method to be able to save huge amount of energy every year.

• Korean Chemical Engineering Research
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• v.59 no.4
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• pp.521-531
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• 2021

Vacuum Pressure Impregnation (VPI) is a process that enhances physical properties by coating some types of epoxy resins on windings of stator used in large rotators such as generators and motors. During vacuum and pressurization of the VPI process, resin gas is generated by vaporization of epoxy resin. When the tank is opened for curing after finishing impregnation, resin gas is leaked out of the tank. If the leaked resin gas spreads throughout the workplace, there are safety and environmental problems such as fire, explosion and respiratory problems. So, exhaust system for resin gas is required during the process. In this study, a case study of exhaust efficiency by location of vent was conducted using Computational Fluid Dynamics (CFD) in order to design a system for exhausting resin gas generated by the VPI process. The optimal exhaust system of this study allowed more than 90% of resin gas to be exhausted within 1,800 seconds and reduced the fraction of resin gas below the Low Explosive Limit (LEL).

• Tunnel and Underground Space
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• v.31 no.3
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• pp.167-183
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• 2021

It is essential to understand the complex thermo-hydro-mechanical-chemical (THMC) coupled behavior in the engineered barrier system and natural barrier system to secure the high-level radioactive waste repository's long-term safety. The heat from the high-level radioactive waste induces thermal pressurization and vaporization of groundwater in the repository system. Groundwater inflow affects the saturation variation in the engineered barrier system, and the saturation change influences the heat transfer and multi-phase flow characteristics in the buffer. Due to the complexity of the coupled behavior, a numerical simulation is a valuable tool to predict and evaluate the THMC interaction effect on the disposal system and safety assessment. To enhance the knowledge of THMC coupled interaction and validate modeling techniques in geological systems. DECOVALEX, an international cooperation project, was initiated in 1992, and KAERI has participated in the projects since 2008 in Korea. In this study, we introduced the main contents of all tasks in the DECOVALEX-2023, the current DECOVALEX phase, to the rock mechanics and geotechnical researchers in Korea.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.35 no.5
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• pp.299-308
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• 2022

This study was conducted to predict the tendency for heat exchange and boil-off gas (BOG) in a liquefied hydrogen tank under sloshing excitation. First, athe fluid domain excited by sloshing was modeled using a multiphase-thermal flow domain in which liquid hydrogen and hydrogen gas are in the saturated state. Both the the volume of fluid (VOF) and Eulerian-based multi-phase flow methods were applied to validate the accuracy of the pressure prediction. Second, it was indirectly shown that the fluid velocity prediction could be accurate by comparing the free surface and impact pressure from the computational fluid dynamics with those from the experimental results. Thereafter, the heat ingress from the external convective heat flux was reflected on the outer surfaces of the hydrogen tank. Eulerian-based multiphase-heat flow analysis was performed for a two-dimensional Type-C cylindrical hydrogen tank under rotational sloshing motion, and an inflation technique was applied to transform the fluid domain into a computational grid model. The heat exchange and heat flux in the hydrogen liquid-gas mixture were calculated throughout the analysis,, whereas the mass transfer and vaporization models were excluded to account for the pure heat exchange between the liquid and gas in the saturated state. In addition, forced convective heat transfer by sloshing on the inner wall of the tank was not reflected so that the heat exchange in the multiphase flow of liquid and gas could only be considered. Finally, the effect of sloshing on the amount of heat exchange between liquid and gas hydrogen was discussed. Considering the heat ingress into liquid hydrogen according to the presence/absence of a sloshing excitation, the amount of heat flux and BOG were discussed for each filling ratio.

• Korean Chemical Engineering Research
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• v.53 no.5
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• pp.557-564
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• 2015

The previous etching, rinsing and drying processes of wafers for MEMS (microelectromechanical system) using SC-$CO_2$ (supercritical-$CO_2$) consists of two steps. Firstly, MEMS-wafers are etched by organic solvent in a separate etching equipment from the high pressure dryer and then moved to the high pressure dryer to rinse and dry them using SC-$CO_2$. We found that the previous two step process could be applied to etch and dry wafers for MEMS but could not confirm the reproducibility through several experiments. We thought the cause of that was the stiction of structures occurring due to vaporization of the etching solvent during moving MEMS wafer to high pressure dryer after etching it outside. In order to improve the structure stiction problem, we designed a continuous process for etching, rinsing and drying MEMS-wafers using SC-$CO_2$ without moving them. And we also wanted to know relations of states of carbon dioxide (gas, liquid, supercritical fluid) to the structure stiction problem. In the case of using gas carbon dioxide (3 MPa, $25^{\circ}C$) as an etching solvent, we could obtain well-treated MEMS-wafers without stiction and confirm the reproducibility of experimental results. The quantity of rinsing solvent used could be also reduced compared with the previous technology. In the case of using liquid carbon dioxide (3 MPa, $5^{\circ}C$, we could not obtain well-treated MEMS-wafers without stiction due to the phase separation of between liquid carbon dioxide and etching co-solvent(acetone). In the case of using SC-$CO_2$ (7.5 Mpa, $40^{\circ}C$), we had as good results as those of the case using gas-$CO_2$. Besides the processing time was shortened compared with that of the case of using gas-$CO_2$.

• The Korean Journal of Pesticide Science
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• v.20 no.4
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• pp.305-311
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• 2016

In cultivation environment, various pesticides are used and some of them could be volatilized into the air. This could affect farmer's health and also cause environmental pollution. This study was carried out to investigate the volatilization of pesticides, and use the reference data for preventing farmer's pesticide intoxication and securing worker safety. The experiment was conducted in a greenhouse using a lysimeter which was of $1m^2$ area and 1.5 m depth filled with upland soil. The pesticides treated in lysimeter soil were ethoprophos (5.0% GR), diazinon (34.0% EC), alachlor (43.7% EC), metolachlor (40.0% EC), chlorpyrifos (2.0% GR), pendimethalin (31.7% EC), carbaryl (50.0% WP), napropamide (50% WP), tebuconazole (25.0% WP) and imidacloprid (2.0% GR). Each pesticide was treated at a concentration of 770.5 mg based on A.I (%). The recovery of pesticide ranged from 77.4 to 99.3%. The volatilized pesticides in air were collected by personal air sampler with PUF tube at 4 l/min flow rate. In addition, temperature and humidity were measured. The collected samples were extracted using acetone in a soxhlet apparatus for 8 hours. The extracted pesticides were resoluted with acetonitrile and diluted 5 times. It was analyzed with LC-MS/MS. For 720 hours experiment, the largest vaporization amount of each pesticide in air was ethoprophos $15.24{\mu}g/m^3$, diazinon $5.14{\mu}g/m^3$, pendimethalin $2.70{\mu}g/m^3$, chlorpyrifos $1.76{\mu}g/m^3$, alachlor $1.40{\mu}g/m^3$, metolachlor $1.12{\mu}g/m^3$, carbaryl $0.27{\mu}g/m^3$, napropamide $0.22{\mu}g/m^3$, tebuconazole $0.11{\mu}g/m^3$ and imidacloprid $0.05{\mu}g/m^3$. The R value (coefficient of correlation) between volatilization and vapor pressure of pesticides is higher than 0.99. Therefore, there is high correlation between volatilization and vapor pressure of pesticides.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.30 no.4 s.48
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• pp.533-541
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• 2004

Atopic dermatitis, also called congenital fever, is a allergic eczema of chronic itching disease. It is a recurrent and familial disease and appears on a wide age group from infant to adult. It is very common, and the ratio of occurrence is about $9{\~}l2\%$ of a child. However. it is showing trend of continuous increase by social and natural environment, food culture, and life style, recently. The human skin plays a barrier role against a physical and chemical stimulus from external environment. According to the latest study, the decreased amount of ceramide in horny layer impairs the bier function and moisture-maintaining function of skin in atopic dematitis patient. Ceramide is a kind of the sphingolipid in which a fatty acid is connected to sphingosin. Ceramide constitutes about $40\%$ of total lipid between keratinocytes and has the function of defense wall and building regular structure to suppress moisture vaporization in horny layer. In horny layer of skin a comified cell is composed of multi-layer structure of a brick shape, and, as for this cornified cell, it is strongly connected by ceramide, cholesterol, and free fatty acid. Here, we described the effects of a cream containing ceramide on the recovery of skin harrier function of atopic dermatitis patient. The safety and efficacy of latex and liquid formula were evaluated as cosmetics for atopic dermatitis. The latex products was composed of intercellular lipid components-ceramide, cholesterol, and free fatty acid-to restore skin barrier function in atopic dermatitis patients. The liquid one contained beta-glucan, magnolia extracts, and licolice extracts, which have skin immunomodulatory and anti-inflammatory effects. It is also confirmed that their possibility on new cosmetic market of atopic dermatitis.

• Journal of The Korean Society of Grassland and Forage Science
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• v.28 no.2
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• pp.139-154
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• 2008

The nearly 75% of animal feed materials used for livestock production are imported every year in Korea. Most of imported feed ingredients are concentrated feeds such as com, wheat, soybean, soybean meal, etc. and they are used as the source materials for the production of assorted feed. The imported concentrated feeds are high in nitrogen and phosphorus. Therefore, the consistent import of feed ingredients may cause an increase of nutrient deposit in our agricultural ecosystem. In the current review, it was discussed with the situation of the feed importation and its nutritional composition to evaluate the nutrient load by the imported feeds onto agricultural ecosystem. The nutrient load caused by imported feeds in agricultural environment was compared with the nutrient demand for crop production. The amounts of N, $P_2O_5\;and\;K_2O$ introduced by the imported fteds in Korea were 371, 140 and 143 Ktons. And, the N, $P_2O_5\;and\;K_2O$ loads excreted from imported feeds in livestock were 148, 84 and 86 Ktons of N, $P_2O_5\;and\;K_2O$ and These nutrient loads by the imported feeds are at the percentage of N 52%, $P_2O_5$ 52% and $K_2O$ 42% in the comparison of total nutrient amounts excreted from livestock animals in Korea. The 82.3% of nutrients excreted from livestock was recycled to crop land as compost and liquid fertilizer, and the others were discharged to river after water treatment processing or disposed to ocean. Also, passing through the recycling process far the production of compost and liquid fertilizer, the amount of nutrients was reduced by the ammonia vaporization of livestock feces and urine. Accordingly, N 81, $P_2O_5$ 74 and $K_2O$ 76 Ktons in the nutrients excreted from livestock were estimated to be utilized in the crop land. Consequently, it was estimated that 44, 48 and 69 Ktons of N, $P_2O_5\;and\;K_2O$ were taken up with crops in the consideration of the ratio of mineralization, and the amounts of leached or deposited N, $P_2O_5\;and\;K_2O$ in crop land were estimated to be 37, 27 and 7 Ktons, respectively. It is estimated that 12%, 34% and 48% of N, $P_2O_5\;and\;K_2O$ introduced by the imported feeds were used by crops, and 10%, 34% and 5% of N, $P_2O_5\;and\;K_2O$ were leached or deposited in agricultural ecosystem. Therefore, considering the leached and deposited amounts of N, $P_2O_5\;and\;K_2O$ originated from the imported feed ingredients, the consistent import of feeds may gradually increase the nutrient load onto agricultural ecosystem.