• Journal of the Korean Institute of Gas
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• v.25 no.1
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• pp.7-13
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• 2021

The re-liquefaction drum is a product that installed spray nozzles at the top to directly spray overcooled LNG into evaporative gas and installed demistors to facilitate gas separation, which was developed to increase the re-liquidity efficiency of small scale re-liquefaction facilities. In the hydrostatic test of the drum, no leakage occurred even at a pressure of 1.5 times the design pressure, but during the BOR(Boil Off Rate) test, the bolt loosening occurred due to contraction and expansion by temperature change. For the continued use of the product, insulation construction on flange connections was developed to enable detachment and attachment, and the comparison of heat load with existing insulation confirmed that it was very small compared to the inlet flow rate in the drum.

• Journal of Medicine and Life Science
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• v.20 no.4
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• pp.166-171
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• 2023

Mixed urinary incontinence (UI) is common in women. This study aimed to assess the efficacy of anti-incontinence surgery in female patients with equally severe stress UI (SUI) and urge UI (UUI). All patients had equal severity of SUI and UUI. The postoperative cure rate was categorized into the cure group (CG) and failure group (FG). Postoperative satisfaction was categorized into the satisfaction group (SG) and the dissatisfaction group (DG). Statistical significance was set at P<0.05. Ninety patients (SG, 73.3%; DG, 26.7%; CG, 93.3%; FG, 6.7%) were included in the study. In the univariate analysis, body mass index (BMI), total bladder capacity, and overactive bladder symptom score (OABSS) were significantly different between the SG and DG groups. Peak urinary flow, Valsalva leak point pressure (VLPP), and OABSS were significantly different between the CG and FG groups. In the multivariate analysis, OABSS (P=0.001) and BMI (P=0.032) were independent predictors of postoperative satisfaction. VLPP (P=0.023) was the only independent factor associated with the postoperative cure rate. In equal severity of SUI and UUI, VLPP was found to be the only independent factor associated with postoperative cure rates. Higher VLPP values were associated with higher cure rates. BMI and OABSS were identified as independent predictors of postoperative satisfaction, with lower BMI and OABSS associated with higher postoperative satisfaction.

• Journal of the Korean Vacuum Society
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• v.18 no.6
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• pp.411-417
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• 2009

The constant volume flow meter system (the chamber volume in the 22 L class) was developed to estimate the pumping speed of the dry pump used for the industry of the next generation semiconductor and display. In order to insure the validity of the system, The base pressure and the leak rate in the enclosed system were checked, which were the $6{\times}10^{-8}\;mbar$ and $1.5{\times}10^{-6}\;mbar-L/s$, respectively. Furthermore, it is also confirmed that the value of throughput limit in this system was as much as 1 order of magnitude lower than that in a previously developed system in the 875 L class. By using this developed system, the pumping speed of the new small dry pump was measured. It is believed that the new developed system can be alternating the expensive constant pressure flow meter system in the range of $1{\times}10^{-2}\;mbar-L/s{\sim}1{\times}10^{-3}\;mbar-L/s$.

• Journal of the Korean Institute of Gas
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• v.25 no.4
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• pp.1-9
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• 2021

The process and facilities of modern chemical plants are becoming increasingly complex, there is possibility of potential risk. Internal chemicals generate stress concentration when operated due to turbulence, laminar flow, pressure, temperature, friction, etc. It causes cumulative fatigue damage, which can damage or rupture chemical facilities and devices. The statistics of chemical accidents found that the highest rate of occurrence was in summer, and in the last five years statistics on chemical accidents, leakage incidents make up a decent percentage of accidents. Chemical leaks can cause serious human damage and economic damage, including explosions and environmental pollution. In this study, based on the leak accident of chemical plant, the risk analysis, and damage effects assessment were estimated using a 3D scanner and FLACS. As a result, if chemicals leak in summer, the risk is higher than in other seasons, the seasonal safety management measures, and countermeasure were estimated.

• Tunnel and Underground Space
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• v.32 no.5
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• pp.285-297
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• 2022

We report results of Extended Leak-Off Test (XLOT) conducted in a large diameter borehole, which is drilled for installation of deep borehole geophysical monitoring system to monitor micro-earthquakes and fault behavior of major fault zones in the southeastern Korean Peninsula. The borehole was planned to secure a final diameter of 200 mm (or more) at a depth of ~1 km, with 12" diameter wellbore to intermediate depths, and 7-7/8" (~200 mm) to the bottom hole depth. We drilled first the 12" borehole to approximately 504 m deep and installed American Petroleum Institute standard 8-5/8" casing, then annulus between the casing and bedrock was fully cemented. XLOT was carried out for several purposes such as confirming casing and cementing integrity, measuring rock stress states. To that end, we drilled additional 4 m long open hole interval to directly inject water and pressurize into the rock mass using the upper API casings. During the XLOT, flow rates and interval pressures were recorded in real time. Based on the logs we tried to analyze hydraulic conductivity of the test interval.

• Journal of the Korean Institute of Gas
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• v.22 no.6
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• pp.28-33
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• 2018

Currently, the government has been expanding the supply of semi-low-pressure in order to solve the problems of unsupplied area of city gas and to secure the economical efficiency of small supplied area. It is mainly supplied from the central storage tank to each household by buried piping. It is necessary to provide such a shutoff valve that can block the excess flow gas due to pipeline leak or rupture when piping is damaged by other construction. For this study, System CFD code named Flownex has been used and a component corresponding to the actual EFV was developed. We compared Flownex results with experimental data to verify the accuracy of Flownex and confirmed the error rate to be around 2%. In this study, pipeline network modeling was done by selecting the LPG supply pipeline in a village and installed the component of the EFV at each junction. We selected the longest pipeline from the main pipeline and set scenarios so that the excess flow occurs by that the pipeline is ruptured before entering the household. The excess flow occurs by the pipeline rupture and the EFV is closed. At this time, we analyzed backflow effects to the other pipeline by closing EFV.

• Economic and Environmental Geology
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• v.27 no.3
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• pp.295-311
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• 1994

A comprehensive in-situ tests are performed to define the hydrogeologic and hydrodispersive characteristics such as hydraulic conductivities, longitudinal dispersivity, and average linear velocities as well as conducting flow-net analysis at the study area. The results show that the study area is very heterogeneous so that hydraulic conductivities range from $6.45{\times}10^{-7}$ to $1.15{\times}10^{-5}m/s$ with average linear velocities of 0.34~0.62m/day. Whole groundwater in upper-most aquifer is discharging into the sea with specific discharge rate of $7.2{\times}10^{-3}$ to $1.3{\times}10^{-2}m/day$. The longitudinal dispersivity of the aquifer is estimated about 4.8m through In-situ injection phase test. The area is highly vulnerable to potential contaminant sources due to it's high value of DRASTIC index ranging from 139 to 155 and also under water table condition with very shallow groundwater level. To delineate contaminant plumes of toxic NaOH and carcinogenic benzene when these substances are assumed to be leaked through existing TSDF at the study area by unexpected accidents or spill, Aquifer Simulation Model (ASM) including Flow and Transport Model is used. Te simulated results reveal that the size of NaOH plume after 5 years continuous leak is about $250{\times}100m$ and benzene after 10 years, $490{\times}100m$. When the groundwater is abstracted about 50 days, which is maximum continuously sustained no-precipitation period during 30 years, with pumping rate of $100m^3/day$, THWELL program shows that the groundwater is adversly affected by sea water intrusion.

• Phonetics and Speech Sciences
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• v.7 no.4
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• pp.93-99
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• 2015

In case of PAS test, the air is sometimes leaked although the mask is tightly attached to the face, which is not reliable on the measured values. Therefore, this study aimed to assist the clinical practice suggesting the test method of PAS without air leakage. In the healthy subjects with 12 males and 12 females over 19 years old, three types of tests were performed on the voicing efficiency among the protocol of PAS Model 6600. They are; first, to attach the mask tightly to the face holding the handle of PAS with the subject's two hands (Method 1); second, to attach the mask tightly to the face holding the handle of PAS with the subject's one hand and pushing the body of PAS strongly with the other hand (Method 2); and third, to attach the mask tightly to the face pushing the upper part of the mask by the tester when the subject attached the mask to his or her face holding the handle of PAS with two hands (Method 3). Upon the study analyses, the mean negative pressure, the mean phonogram, subglottic air pressure, and voicing efficiency were shown to be statistically significantly different during PAS test in males depending on the methods. (p<.05) In case of females, only the target airflow rate showed significant difference depending on the methods during PAS test. (p<.001) In conclusion, Method 2 enhanced the noise level and strength while Method 1 was likely to leak the air more compared to the other two methods in males. In case of females, Method 1 showed significant leakage of the air flow. Not to allow the air flow leakage without affecting the outcome of PAS test, it will be the most useful for the tester to push the mask to the subject's face tightly (Method 3).

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1996.06a
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• pp.508-508
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• 1996

;The growth of films have considerable interest in the field of superlattice structured multi-layer epitaxy led to realization of new devices concepts. Molecular beam epitaxy (MBE) with in situ observation by reflection high-energy electron diffraction (RHEED) is a key technology for controlled layered growth on the atomic scale in oxide crystal thin films. Also, the combination of radical oxygen source and MBE will certainly accelerate the progress of applications of oxides. In this study, the growth process of single crystal films using by MBE method is discussed taking the oxide materials of Bi-Sr-Ca-Cu family. Oxidation was provided by a flux density of activated oxygen (oxygen radicals) from an rf-excited discharge. Generation of oxygen radicals is obtained in a specially designed radical sources with different types (coil and electrode types). Molecular oxygen was introduced into a quartz tube through a variable leak valve with mass flowmeter. Corresponding to the oxygen flow rate, the pressure of the system ranged from $1{\;}{\times}{\;}10^{-6}{\;}Torr{\;}to{\;}5{\;}{\times}{\;}10^{-5}$ Torr. The base pressure was $1{\;}{\times}{\;}10^{-10}$ Torr. The growth of Bi-oxides was achieved by coevaporation of metal elements and oxygen. In this way a Bi-oxide multilayer structure was prepared on a basal-plane MgO or $SrTiO_3$ substrate. The grown films compiled using RHEED patterns during and after the growth. Futher, the exact observation of oxygen radicals with MBE is an important technology for a approach of growth conditions on stoichiometry and perfection on the atomic scale in oxide. The oxidization degree, which is determined and controlled by the number of activated oxygen when using radical sources of two types, are utilized by voltage locked loop (VLL) method. Coil type is suitable for oxygen radical source than electrode type. The relationship between the flux of oxygen radical and the rf power or oxygen partial pressure estimated. The flux of radicals increases as the rf power increases, and indicates to the frequency change having the the value of about $2{\times}10^{14}{\;}atoms{\;}{\cdots}{\;}cm^{-2}{\;}{\cdots}{\;}S^{-I}$ when the oxygen flow rate of 2.0 seem and rf power 150 W.150 W.

• Progress in Superconductivity and Cryogenics
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• v.8 no.1
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• pp.59-64
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• 2006

A closed-loop cryogenic cooling system for high field magnets is presented. This design is motivated by our recent development of cooling system for 21 tesla Fourier Transform ion Cyclotron Resonance (FT-ICR) superconducting magnets without any replenishment of cryogen. The low temperature superconducting magnets are immersed in a subcooled 1.8 K bath, which is connected hydraulically to the 4.2 K reservoir through a narrow channel. Saturated liquid helium is cooled by Joule-Thomson heat exchanger and flows through the JT valve, isenthalpically dropping its pressure to approximately 1 6 kPa, corresponding saturation temperature of 1.8 K. Helium gas exhausted from pump is now recondensed by two-stage cryocooler located after vapor purify system. The amount of cryogenic Heat loads and required mass flow rate through closed-loop are estimated by a relevant heat transfer analysis, from which dimensions of JT heat exchanger and He II heat exchanger are determined. The detailed design of cryocooler heat exchanger for helium recondensing is performed. The effect of cryogenic loads, especially superfluid heat leak through the gap of weight load relief valve, on the dimensions of cryogenic system is also investigated.