• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.04a
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• pp.73-76
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• 2003

SF$_{6}$ (Sulfur Hexafluoride) is a gaseous compound whose use is being greatly increased recently. The compound has a negligible background concentration from natural sources and is stable in most of groundwater environments. Therefore, SF$_{6}$ has potential for a dating tool for young groundwater. It has many advantages over chlorofluorocarbons (CFCs) for groundwater investigation that sampling procedure is much simpler than CFCs and its growth is continued up to at least near future in the atmosphere. However, solubility of SF$^{6}$ is so low that excess air causes large uncertainties in recharge date of groundwater. To compensate the limitation, $N_2$/Ar method can be employed to estimate excess air content. A groundwater study is currently carrying out in Jeju Island using SF$_{6}$ as an environmental tracer, Well waters and spring waters were sampled for SF$_{6}$ and $N_2$/Ar. To establish SF$_{6}$ input history in the study area, air sampling is being conducted in the area near the center of the island on a monthly and weekly basis. Based on the present data, the level of SF$_{6}$ concentration in the atmosphere of the Island is corresponding to the trend of the Northern Hemisphere.

• Proceeding of EDISON Challenge
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• 2017.03a
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• pp.677-687
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• 2017

Caffeine has a long history of human consumption but the consumption of caffeine due to caffeinated energy drinks(CEDs) is rapidly growing. Marketing targets of CED sales are children, adolescents and young adults, possibly caffeine-sensitive groups and its effect for them can be significantly different from healthy adults. Caffeine-related toxicities among these groups are growing in number and a number of countries are recognizing severity of caffeine toxicities. Previous research showed prediction of maximal plasma caffeine concentration profiles after the single CED ingestion and the primary aim of this study is to visually predict plasma caffeine concentration after the single and multiple ingestion of standard servings of CED. Based on the population pharmacokinetic model using Monte Carlo simulation, prediction of caffeine concentration leading to caffeine intoxication in the sensitive groups is quantitatively presented and visualized. This research also broadens the perspective by creating and utilizing diverse open science tools including R package, Edison Science App and Shiny apps.

• Ceramist
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• v.22 no.4
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• pp.357-367
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• 2019

Secondary Ion Mass Spectrometry(SIMS) is an analytical method that measures the distribution and concentration of elements or compounds by analyzing the mass of secondary ions released by irradiating ion beams with energy of hundreds eV to 20 keV on the sample surface. Unlike other similar analytical instruments, SIMS directly detect the elemental ions that constitute a sample, allowing you to accurately identify components and obtain concentration information in the depth direction. It is also a great feature for measuring isotopes and analyzing light elements, especially hydrogen. In particular, with the development of materials science, there is an increasing demand for trace concentration analysis and isotope measurements in the micro-regions of various materials. SIMS has a short history compared to other similar methods; nevertheless, SIMS is still advancing in hardware and is expected to contribute to the development of materials science through research and development of advanced analytical techniques.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.5
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• pp.887-897
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• 2018

3D time history analysis was performed on vertical shaft-tunnel connection to provide insight into the dynamic stress-strain behavior of the connection considering the effects of soil layers, periodic characteristics and wave direction of earthquakes. MIDAS GTS NX based on FEM (Finite Element Method) was used for this study. From this study, it is revealed that the maximum displacement occurred at the upper part of the connection when the long period seismic waves propagate through the tunnel direction in soft ground. Also, stress concentration occurs due to different behaviors of vertical shaft and tunnel, and the stress concentration could be influence for safety on the connection. The results of this study could be useful for the seismic performance design of vertical shaft-tunnel connection.

• Clinical and Experimental Reproductive Medicine
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• v.43 no.2
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• pp.97-101
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• 2016

Objective: Growth hormone and its mediator, insulin-like growth factor-1 (IGF-1), have been suggested to exert gonadotropic actions in both humans and animals. The present study was conducted to assess the relationship between serum IGF-1 concentration, seminal plasma concentration, and sperm parameter abnormalities. Methods: A total of 79 men were enrolled in this study from December 2011 to July 2012 and were prospectively analyzed. Patient parameters analyzed included age, body mass index, smoking status, urological history, and fertility history. Patients were divided into four groups based on their semen parameters: normal (A, n=31), abnormal sperm motility (B, n=12), abnormal sperm morphology (C, n=20), and two or more abnormal parameters (D, n=16). Patient seminal plasma and serum IGF-1 concentrations were determined. Results: Patient baseline characteristics were not significantly different between any of the groups. The serum IGF-1 levels in groups B, C, and D were significantly lower than the levels in group A; however, the seminal plasma IGF-1 levels were not significantly different between any of the groups. Conclusion: Men with abnormal sperm parameters had significantly lower levels of serum IGF-1 compared with men with normal sperm parameters. Seminal plasma IGF-1 levels, however, did not differ significantly between the groups investigated here. Further investigations will be required to determine the exact mechanisms by which growth hormone and IGF-1 affect sperm quality.

• The Bulletin of The Korean Astronomical Society
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• v.27 no.1
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• pp.36-36
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• 2002

Everyday meteors can be classified into sporadic meteors and shower-meteors. We compile the meteor records in the astronomical archives in the history book of Koryo dynasty (Koryosa), and investigate the spatial distribution of meteories along the orbit of the Earth during the period between the 10th century and the 14th century. We discover several peaks in cumulative frequency of meteors excluding showers, which means the presence of the strong concentrations of meteorites at the ecliptic longitudes. We also compiled the whole records of meteor showers during the same period from the history books of Korean, Japan, and China, and then compare dates of their display with dates obtained in Koryosa archive. Especially the strong concentration at 27 July is exactly coincident with a meteor shower at the same date. We devide the data into two sets, which are before and after 1200 A.D., and find out that the strength of meteor concentration has been changing. Especially the shower at 27 July weaken as time goes by.

• Journal of Preventive Medicine and Public Health
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• v.33 no.4
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• pp.477-483
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• 2000

Objectives : To obtain reference values for the pulmonary asbestos and non-asbestos fiber contents of residents in Korea and to compare them with similar results from Japan. Methods : The autopsied lung specimens from 22 deceased people (20 males and 2 females) in Pohang, without any known occupational history of asbestos exposure, were analyzed for incidence of asbestos and non-asbestos fibers by transmission electron microscopy with energy dispersive X-ray analysis after using low temperature ashing procedures. Results : Chrysotite fiber (46.2%) was the major fiber type found in the lungs of the subjects. The asbestos fiber concentrations found in males and females were $0.09\times10^6$ fiberss(g of dry lungs) and $0.30\times10^6$ fibers/(g of dry lungs), respectively, showing a geometric mean concentration $0.09\times10^6$ fibers/(g of dry lung tissue), due to the predominance of males in the sample. The non-asbestos fiber contents in males and females were $4.61\times10^6$ fibers/(g of dry lungs) and $17.79\times10^6$ fibers/(g of dry lungs), respectively, with a geometric mean concentration $5.21\times10^6$ fibers/(g of dry lung tissue). Conclusions : Residents in Pohang had significantly lower levels of both asbestos and non-asbestos fibers than urban residents in Korea. Furthermore, Koreans had significantly lower levels of both asbestos and non-asbestos fibers than Japanese.

• Structural Engineering and Mechanics
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• v.76 no.3
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• pp.421-433
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• 2020

Masonry infills are normally considered as non-structural elements in design practice, therefore, the interaction between the bounding frame and the strength contribution of masonry infills is commonly ignored in the seismic analysis work of the RC frames. However, a number of typical RC frames with irregular distributed masonry infills have suffered from undesirable weak-story failure in major earthquakes, which indicates that ignoring the influence of masonry infills may cause great seismic collapse risk of RC frames. This paper presented the investigation on the risk of seismic collapse of RC frames with irregularly distributed masonry infills through a large number of nonlinear time history analyses (NTHAs). Based on the results of NTHAs, seismic fragility curves were developed for RC frames with various distribution patterns of masonry infills. It was found that the existence of masonry infills generally reduces the collapse risk of the RC frames under both frequent happened and very strong earthquakes, however, the severe irregular distribution of masonry infills, such as open ground story scenario, results in great risk of forming a weak story failure. The strong-column weak-beam (SCWB) ratio has been widely adopted in major seismic design codes to control the potential of weak story failures, where a SCWB ratio value about 1.2 is generally accepted as the lower limit. In this study, the effect of SCWB ratio on inter-story drift distribution was also parametrically investigated. It showed that improving the SCWB ratio of the RC frames with irregularly distributed masonry infills can reduce inter-story drift concentration index under earthquakes, therefore, prevent weak story failures. To achieve the same drift concentration index limit of the bare RC frame with SCWB ratio of about 1.2, which is specified in ACI318-14, the SCWB ratio of masonry-infilled RC frames should be no less than 1.5. For the open ground story scenario, this value can be as high as 1.8.

• Journal of Acupuncture Research
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• v.22 no.2
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• pp.1-12
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• 2005

Objective: With the onset of stroke, white blood cells release several proinflammatory cytokines, including interleukin (IL)-6, IL-10, and tumor necrosis factor $(TNF)-{\alpha}$. It has been proven in previous studies that the release of these cytokines is related to the extent of damage to the brain and to overall prognosis. However, no studies have yet been performed to determine the connection with IL-6 and IL-10. Thus, this study is performed to see whether polymorphisms of IL-6, IL-10, and $TNF-{\alpha}$ genes that show increased serum concentration with the onset of stroke are related to stroke attack in Koreans. Methods : Peripheral blood samples derived from patients with stroke (n=100) and healthy controls (n=100) were taken under informed consent. In subjects with stroke, blood samples were obtained within 24 hours of stroke onset. Genomic DNA was isolated using the Wizard DNA Purification Kit (Promega, Madison, WI). Results : 1. Subjects with Heterozygote (GA) and Homozygote (AA) $TNF-{\alpha}$ gene types showed 2.433 and 20.457 times higher risks of being attacked by stroke, respectively, compared to subjects with wild type (GG) $TNF-{\alpha}$ gene type. The data was still statistically significant after adjusting for age, sex, history of smoking, and history of alcohol drinking. 2. Subjects with Homozygote (CC) IL-6 gene type showed 182.033 times higher risk of being attacked by stroke, compared to subjects with wild type (GG) IL-6 genes. This data was statistically insignificant (p=0.700). The data was still statistically insignificant after adjusting for age, sex, history of smoking, and history of alcohol drinking. 3. Subjects with Heterozygote (GA) and Homozygote (GG) IL-10 gene types showed 8.785 and 3.303 times higher risks of being attacked by stroke, respectively, compared to subjects with wild type (AA) IL-10 genes. The data was still statistically insignificant after adjusting for age, sex, history of smoking, and history of alcohol drinking. Conclusion : Our results suggest that the investigated $TNF-{\alpha}$ and IL-10 gene polymorphisms play an important role in stroke attack, but IL-6 gene polymorphism has not been found to associated with stroke.

• Journal of The Korean Society of Clinical Toxicology
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• v.1 no.1
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• pp.34-39
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• 2003

Carisoprodol (CSP) is commonly prescribed as a skeletal muscle relaxant. Recently, we encountered 7 suicidal cases in which carisoprodol was detected. We developed a rugged, sensitive, and specific method for the determination of CSP and meprobamate (MPB) by GC and GC/MS. Postmortem blood concentrations of CSP and MPB ranged 22.9-124.4 ,$\mu$g/ml and its metabolite, 26.8-144.5 ,$\mu$g/ml respectively. Among 7 cases studied, Only CSP was ingested in 4 cases and combination of CSP and dextromethorphan was ingested in 2 cases according to the case history and one case was with ethanol. The order of the tissue concentration of CSP and MPB was liver> kidney > brain, and the concentration of MPB was higher than that of CSP in all tissues. The MPB /CSP concentration ratios of urine, bile juice, liver, kidney, brain and blood were 15.7, 4.0, 1.2, 1.4, 1.4 and 1.0 respectively. There was a big difference in concentration of CSP and MPB in 7 cases due to differences in the amount of dose administered and time to death after dosing.