• Geomechanics and Engineering
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• v.21 no.2
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• pp.187-200
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• 2020

In the current work, a series of three-dimensional finite element analyses have been conducted to investigate the behaviour of pre-existing single piles in response to adjacent tunnelling by considering the tunnel face pressures and the relative locations of the pile tips with respect to the tunnel. Via numerical modelling, the effect of the face pressures on the pile behaviour has been analysed. In addition, the analyses have concentrated on the ground settlements, the pile head settlements and the shear stress transfer mechanism at the pile-soil interface. The settlements of the pile directly above the tunnel crown (with a vertical distance between the pile tip and the tunnel crown of 0.25D, where D is the tunnel diameter) with a face pressure of 50% of the in situ horizontal soil stress at the tunnel springline decreased by approximately 38% compared to the corresponding pile settlements with the minimum face pressure, namely, 25% of the in situ horizontal soil stress at the tunnel springline. Furthermore, the smaller the face pressure is, the larger the tunnelling-induced ground movements, the axial pile forces and the interface shear stresses. The ground settlements and the pile settlements were heavily affected by the face pressures and the positions of the pile tip with respect to the tunnel. When the piles were inside the tunnel influence zone, tensile forces were induced on piles, while compressive pile forces were expected to develop for piles that are outside the influence zone and on the boundary. In addition, the computed results have been compared with relevant previous studies that were reported in the literature. The behaviour of the piles that is triggered by adjacent tunnelling has been extensively examined and analysed by considering the several key features in substantial detail.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.2
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• pp.38-43
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• 2015

Tungsten inert gas (TIG) welding is commonly used in industries that require airtightness, watertightness, oiltightness, and precision. It is a non-consumable welding method that is commonly used for the welding of non-ferrous metals, but it can be used to weld most metals. The methods of TIG welding can be divided into three types. The first, manual welding is done directly on the metal by a welder with a torch. The second, semi-automatic welding, gets help from a material supplying machine, but it is conducted by a welder. Lastly, automated welding is conducted fully by a machine during its process and operation. Depending on the selection of electrode, the amount of heat that is applied to the base material and the electrode rod changes and makes the shape of welded parts different. A direct-current positive electrode was used for this study. Through the change of shielding gas type on a structural steel (SS-400) that is commonly used in industry, the composition and shape changes in welded parts were detected after welding. The heat-affected area, hardness value, and tensile strength were also identified through hardness testing and tensile testing. In this study, it was found that the higher hardness value of the heat-affected is, the weaker the tensile strength becomes.

• Journal of the Korean GEO-environmental Society
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• v.24 no.12
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• pp.53-60
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• 2023

Recently, along with the improvement of high-speed rail and road design speed, the proportion of tunnel construction work is increasing proportionally. In particular, the construction of long tunnels is rapidly increasing due to the mountainous terrain of our country. In this way, due to the trend of tunnels becoming longer, it is difficult to design and construct tunnels by avoiding fault zones. In the case of tunnel construction in mountainous areas, ground investigation is often difficult even during design due to the topographical conditions, making precise ground investigation difficult, and as a result, the upper part of the tunnel is damaged during tunnel construction. When fault zones, which are vulnerable to weathering, exist, the stability of the tunnel during excavation is directly affected by the fault zone distribution, strength characteristics, and groundwater distribution range. In particular, when a fault zone is distributed in the upper part of a tunnel, damage such as tunnel collapse and excessive displacement may occur, and in order to prevent this in advance, countermeasures must be established through analysis of similar cases. Therefore, in this study, when a large-scale fault zone exists in the upper part of a tunnel, the relationship and characteristics of damage to the tunnel structure were analyzed.

• Journal of Acupuncture Research
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• v.23 no.2
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• pp.103-111
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• 2006

Objectives : Deer antler Water Extract(DAE), prepared from the pilose antler of Cervus korean TEMMINCK var. mantchuricus Swinhoe (Nokyong), a traditional immuno-suppressive and immuno-activating Korean herbal-acupuncture, is thought to play an important role in human bone remodeling. Methods : To determine whether DAE can induce the differentiation of resting zone chondrocytes(RC) or not, confluent cell cultures were pretreated for 24, 36, 48, 72, and 120hrs with DAE. At the end of pretreatment, the media were replaced with new media containing $10^{-10}{\sim}10^{-8}M\;1,25-(OH)_2D_3$ and the cells incubated for an additional 24hrs. Results : This second treatment was chosen because prior studies had shown that only the more mature growth zone chondrocytes(GC) respond to this vitamin $D_3$ metabolite. The effect of DAE pretreatment on cell maturation was confirmed by measuring alkaline phosphatase (ALPase)-specific activity. Changes in matrix protein synthesis were examined by measuring collagen synthesis, as well as $^{35}SO_4$ incorporation into proteoglycans. When RC cells were pretreated for 120h with DAE, treatment with $1,25-(OH)_2D_3$ caused a dose-dependent increase in ALPase-specific activity and collagen synthesis, however, the proteoglycan production was not affected. RC cells pretreated with $1,25-(OH)_2D_3$ responded like RC cells that had not received any pretreatment. Conclusion : These results indicate that DAE directly regulates the maturation of RC chondrocytes into GC chondrocytes. Therefore it was indicated that DAE may play a significant role in regulating chondrocyte maturation during endochondral ossification.

• Journal of Welding and Joining
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• v.5 no.2
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• pp.44-52
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• 1987

The fracture toughness, $J_{IC}$ of high frequency electric resistance welded steel pipe for smooth and side-grooved CT specimen was evaluated by unloading compliance method. The crack growth, .${\delta}a$ was obtained from the equation of Donald and Saxena & Hudak, and $J_{IC}$ was determined from the curve of J-${\delta}a$ relations. The crack growth on the experiment using unloading compliance method is underestimated as compared with ${\delta}a$ measured directly by the SEM, so the reliability of $J_{IC}$ from saxena & Hudak equation is large than that from Donald. The $J_{IC}$ value of side-grooved CT Specimen is estimated less than that of smooth, and this is the effect of the side-groove, the shear-lip of crack tip and the reduction of crack tunnelling phenomena.

• Korean Journal of Remote Sensing
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• v.33 no.3
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• pp.287-299
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• 2017

The Southern Volcanic Zone (SVZ) of Chile consists of many volcanoes, including the Mt.Villarrica and Mt.Llaima, and the two volcanoes are covered with snow at the top of Mountain. The purpose of this study is to analyze the relationship between the ice caps and the volcanic activity of the two volcanoes for 25 years by using the satellite image data are available in a time series. A total of 60 Landsat-5 TM and Landsat-7 ETM + data were used for the study from September 1986 to February 2011. Using NDSI (Normalized Difference Snow Index) algorithm and SRTM DEM, snow cover and snowline were extracted. Finally, the snow cover area, lower-snowline, and upper-snowline, which are quantitative indicators of snow cover change, were directly or indirectly affected by volcanic activity, were extracted from the satellite images. The results show that the volcanic activity of Villarrica volcano is more than 55% when the snow cover is less than 20 and the lower-snowline is 1,880 m in Llaima volcano. In addition, when the upper-snowline of the two volcanoes is below -170m, it can be confirmed that the volcano is differentiated with a probability of about 90%. Therefore, the changes in volcanic snowfall are closely correlated with volcanic activity, and it is possible to indirectly deduce volcanic activity by monitoring the snow.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.24 no.1
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• pp.1-14
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• 2021

The Ministry of Environment of Korea has been releasing Asiatic black bears since 2004 at Jirisan National Park. It exceeded the target number of Asiatic black bears in 2018. As of July 2020, in addition to 67 traceable bears, many Asiatic black bears are dispersed outside Jirisan National Park. Jirisan National Park is a very dense place with more than 3 million visitors every year. In this study, the roads and trails through Jirisan National Park were considered to be the main dispersion factors of Asiatic black bears, and the fragmentation analysis was conducted. As of July 2017, the length of roads and trails in Jirisan National Park was 363.4km. Based on this, Jirisan National Park was fragmented into 163 patches. There is only one place that maintains a single area of more than 50㎢ that is suitable for large mammals to inhabit, and 141 places are less than 5㎢. There are 6 patches of 24 to 200㎢ area suitable for living of large mammals including Asiatic black bears, in Jirisan National Park. Compared to the announcement made by the Korea National Park Service in 2014, activities of Asiatic black bears were rare in areas below 5㎢ area and the frequency of activities was high in more than 20㎢ area. This shows that human activities in protected areas such as national parks can directly affect the activities of wild animals, including Asiatic black bears. Therefore, efforts should be made to improve the habitat of Asiatic black bears by reducing the pressure of visiting for Jirisan National Park. In addition, as a result of analyzing the fragmentation of the park's natural conservation zone 107.7km, 45% of the trail of Jirisan National Park, was opened, which is more fragmentation than other use zones. The park nature conservation zone accounts for about 32% of the total area of Jirisan National Park, but the average patch area is only 2.93㎢ and seven large shelters are located. Therefore the Asiatic black bears are negatively affected. This is the result of inconsistent national park use zone setting and actual park management. In overseas countries, research is active on the negative effects of human activity on ecosystems in protected areas. However, there is a lack of research of that in Korea. Thus, that research is required for protection area management in the future.

• Nuclear Engineering and Technology
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• v.52 no.8
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• pp.1732-1741
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• 2020

The structural integrity of welded joints in the reactor pressure vessel (RPV) is directly related to the safety of nuclear power plants. The RPV is made from SA508-III steel in a pressurized water reactor. In this study, we investigated the effects of temperature on the tensile and fracture toughness properties of Chinese SA508-III welded joint in different sampling areas in order to provide reference data for structural integrity assessments of RPVs. The specimens used in tensile and fracture toughness tests were fabricated from the base metal (BM), weld metal (WM), and the heat-affected zone (HAZ) in the welded joint. The representative testing temperatures included the ambient temperature (20 ℃), upper shelf temperature (100 ℃), and service temperature (320 ℃). The results showed that temperature greatly affected the fracture toughness (JIC) values for the SA508-III welded joint. The JIC values for BM and HAZ both decreased remarkably from 20 ℃ to 320 ℃. The fracture morphologies showed that the BM and HAZ in the welded joint exhibited fully ductile fracture at 20 ℃, whereas partial cleavage fracture was mixed in ductile fracture mode at 100 ℃ and 320 ℃. The WM exhibited the ductile and cleavage fracture mixed mode at various temperatures, and the JIC values showed slight changes.

• Explosives and Blasting
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• v.28 no.2
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• pp.1-16
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• 2010

This study focuses on the phenomenon that the blast damaged zone developed on rock slope surfaces can be affected by joint characteristics rather than by explosive power when the pre-splitting is applied to excavate a jointed rock slope. The characteristics of rock joints on a slope were investigated and categorized them into 4 cases. Also an image processing system has been used for comparing the distribution pattern of rock blocks. From this investigation, it was found that the rock blocks bigger than 2,000 mm occupied 42% in the case of single joint set and it showed the well efficiency of pre-splitting blast. In cases of 2~3 parallel joint sets and 2~3 intersecting joint sets are developed on rock surfaces, the rock blocks in the range of 1,000~2,000 mm occupied 43.6% and 35.8%, respectively, and it showed that the efficiency of pre-splitting was decreased. When more than 3 joint sets are randomly developed, however, the rock blocks in the range of 250~500 mm occupied 35% and there was no block bigger than 1,000 mm. This denotes that the blasting with pre-splitting was not effective. The numerical analysis using PFC2D showed that the blast damaged zone in a rock mass could be directly influenced by the pre-splitting. It is, therefore, required to investigate the discontinuity pattern on rock surfaces in advance, when the pre-splitting method is applied to excavate jointed rock slopes and to apply a flexible blating design with a consideration of the joint characteristics.

• The Korean Journal of Nuclear Medicine Technology
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• v.17 no.2
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• pp.101-106
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• 2013

Purpose: As UBC IRMA is being tested, patients out of the reference value are reacting within the value again a few days later the urine collection tested, which causes the reliability of the test to decrease as a result. In this study, we can assume that the physiological changes in the factors would affect the results. The purpose of the study is to find out whether hematuria and proteinuria in the sample as well as the interval time (3 hours or more recommended) have affected the results. As a result, we could discover the changes in factors and increase the reliability of the test. Materials and Methods: 468 people (female: 249, male: 219) who came for the check-up were presented herein for medical examination from 2013.3.15 to 2013.1.2. Some people out of 468 who have reacted onto the reference value were divided into group low titer zone, ow-middle titer zone, and middle-high titer zone and tested for hematuria and proteinuria. During that period, 48 outpatients were asked to fill in a questionnaire regarding the urination interval time. The reagents used were (IDL Biotech AB, Sweden) and UBC IRMA. Results: Of the patients that are formed in the reference value of ($0.1-34.0{\mu}g/L$) turn out to be 52.7 years average age in their low concentration, ($mean{\pm}SD$) of the value of $0.10{\pm}0.02{\mu}g/L$. Among 80 people (50.8%, female: 49.2%), 16 patients (20%) have shown reaction to microscopic hematuria and 10 patients (12.5%) responded to proteinuria. In the average low concentration under 52.5 years of average age, 43 people (53%) have shown reaction to microscopic hematuria and 21 people (26.3%) are proteinuric patients out of 80 patients (male: 50.8%, female: 51.3%). In the middle high concentration of $11.8{\pm}4.82{\mu}g/L$ under the average age 51.7 years, 35 patients (53%) have responded to the microscopic hematuria and proteinuric patients are 26 people (39.3%) out of 66 people (men: 44%, women: 56%). In addition, in the concentration of $51.7{\pm}43.5{\mu}g/L$, some patients who get out of the reference value are observed as the average age of 52.0. 11 patients (78.6%) out of 14 (male: 35.7%, female: 64.3%) react to the microscopic hematuria. There show 6 people (42.8%) who turn out to be as proteinuric patients. As for the interval time, $1.67{\pm}3.71{\mu}g/L$ was the average value among 48 patients (female: 45.8%, male: 54.2%). Conclusion: We cannot see if proteinuria and hematuria directly affect abnormal results of inspection of 8,18 cytokeratin; however, we can find out that they statistically have an influence on highly generating UBC among several mechanisms. Also, although urination interval time was various every 15 minutes, we it does not affect these results.