• Journal of the Korean Institute of Gas
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• v.26 no.4
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• pp.41-57
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• 2022

The global demand for carbon neutrality in response to climate change is in a situation where it is necessary to prepare countermeasures for carbon trade barriers for some countries, including Korea, which is classified as an export-led economic structure and greenhouse gas exporter. Therefore, digital transformation, which is one of the predictable ways for the carbon-neutral transition model to be applied, should be introduced early. By applying digital technology to industrial gas manufacturing facilities used in one of the major industries, high-tech manufacturing industry, and hydrogen gas facilities, which are emerging as eco-friendly energy, abnormal detection, and diagnosis services are provided with cloud-based predictive diagnosis monitoring technology including operating knowledge. Here are the trends. Small and medium-sized companies that are in the blind spot of carbon-neutral implementation by confirming the direction of abnormal diagnosis predictive monitoring through optimization, augmented reality technology, IoT and AI knowledge inference, etc., rather than simply monitoring real-time facility status It can be seen that it is possible to disseminate technologies such as consensus knowledge in the engineering domain and predictive diagnostic monitoring that match the economic feasibility and efficiency of the technology. It is hoped that it will be used as a way to seek countermeasures against carbon emission trade barriers based on the highest level of ICT technology.

• Tunnel and Underground Space
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• v.32 no.5
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• pp.312-326
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• 2022

The generalized Hoek-Brown (GHB) criterion, which is recognized as one of the standard failure conditions for rock mass, is specialized for rock engineering applications and covers a wide range of rock mass conditions. Accordingly, many research efforts have been devoted to the incorporation of this criterion into the stability analysis of rock structures. In this study, the slip-line analysis method, which is a kind of elastoplastic analysis method, is combined with the GHB failure criterion to derive analytical equations that can easily calculate the plastic radius and stress distribution in the vicinity of the circular tunnel. In the process of derivation of related formulas, it is assumed that the behavior of rock mass after failure is perfectly plastic and the in-situ stress condition is hydrostatic. In the formulation, it is revealed that the plastic radius can be calculated analytically using the two respective tangential friction angles corresponding to the stress conditions at tunnel wall and elastic-plastic boundary. It is also shown that the plastic radius and stress distribution calculated using the derived analytical equations coincide with the results of Lee & Pietruszczak's numerical method published in 2008. In the latter part of this paper, the influence of the quality of the rock mass on the size of the plastic zone, the stress distribution, and the change of the tangential friction angle was investigated using the derived analytical equations.

• Korean Journal of Remote Sensing
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• v.39 no.3
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• pp.257-268
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• 2023

Sea ice plays an important role in Earth's climate by regulating the amount of solar energy absorbed and controlling the exchange of heat and material across the air-sea interface. Its growth, drift, and melting are monitored on a regular basis by satellite observations. However, low-resolution products with passive microwave radiometer have reduced accuracy during summer to autumn when the ice surface changes rapidly. Synthetic aperture radar (SAR) observations are emerging as a powerful complementary, but previous researches have mainly focused on winter ice. In this study, sea ice drift tracking was evaluated and analyzed using SAR images and tracker with global positioning system (GPS) during late summer-early autumn period when ice surface condition changes a lot. The results showed that observational uncertainty increases compared to winter period, however, the correlation coefficient with GPS measurements was excellent at 0.98, and the performance of the ice tracking algorithm was proportional to the sea ice concentration with a correlation coefficient of 0.59 for ice concentrations above 50%.

• Korean Chemical Engineering Research
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• v.61 no.3
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• pp.419-425
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• 2023

This paper presents the research results of analyzing the high-temperature corrosion characteristics of three currently commercialized heat exchanger tube materials under actual operating conditions of a biomass power plant. In order to precisely analyze the high-temperature corrosion characteristics of these materials, a high-temperature corrosion evaluation device was installed in the power plant equipment, which allows for adjusting the surface temperature of the heat exchanger tubes. Experiments were conducted for approximately 300 hours under various temperature and operating conditions. In this study, the commercialized heat exchanger tube materials used were SA213T12, SA213T22, and SA213T91 alloys. In order to objectively analyze the high-temperature corrosion characteristics of each material, an international standard-based process to remove corrosion products was applied to obtain the weight change of the specimens, and the average thickness loss and corrosion rate were derived. Thus, the high-temperature corrosion results for each condition were quantitatively compared and analyzed. In addition, in order to increase the reliability of the high-temperature corrosion evaluation method introduced in this study, the surface and cross-sectional corrosion of the specimens were confirmed by using scanning electron microscopy and energy-dispersive X-ray analysis. Based on these analysis results, it was found that the corrosion resistance of the commercial heat exchanger materials increases as the content of chrome and nickel in the composition increases. Additionally, it was found that the corrosion phenomenon is rapidly accelerated as the surface temperature increases. Finally, the replacement period (lifetime) of the heat exchanger tubes under each condition could be inferred through this study.

• Analytical Science and Technology
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• v.21 no.2
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• pp.93-101
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• 2008

The application of solid phase microextraction (SPME) is generally conducted by directly immersing the fiber into the liquid sample or by exposing the fiber in the head space (HS). The extraction temperature, the time of incubation, and application of stirring are often designated to be the most important parameters for achieving the best extraction efficiencies of HS-SPME analysis. In this study, relative importance of these three analytical parameters involved in the HS-SPME method is evaluated using a polydimethylsiloxane/carboxen (PDMS/CAR) fiber. To optimize its operation conditions the competing relationships between different parameters were investigated by comparing the extraction efficiency based on the combination of three parameters and two contracting conditions: (1) heating the sample at 30 vs. 50 C, (2) exposing samples at two durations of 10 vs. 30 min, and (3) application of stirring vs. no stirring. According to our analysis among 8 combination types of HS-SPME method, an extraction condition termed as S50-30 condition ((1) 1200 rpm stirring, (2) $50^{\circ}C$ exposure temp, and (3) 30 min exposure duration) showed maximum recovery rate of 45.5~68.5% relative to an arbitrary reference of direct GC injection. According to this study, the employment of stirring is the most crucial factor to improve extraction efficiency in the application of HS-SPME.

• Journal of The Geomorphological Association of Korea
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• v.18 no.3
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• pp.65-81
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• 2011

The landforms based on granite and basalt in Gosung, Gangwon province were analysed. Some part of this area experienced volcanic activities while most of the area was experiencing erosion of weathered mantle(saprolites) of mesoic granites during cenozoic period. Two different lithologies affect the mode of landscape evolution. The basalt covers the mountain tops as a 'cap rock' with flat surfaces. It shows relatively fresh rock surface with cliff or steep slops at the boundary with weathered granite. The blocks detached from the cliff accumulated at the foot of the cliff(talus) or moved and filled the valley(block streams). These debris slopes cover the deeply weathered granites. In the case of Oeum Mt. and Duibaekjae, the number of point of origin of the basalt flow is not clear. The orientation of blocks from block stream coincides with slope aspects and it can be assumed that the bolcks were moved by solifluction. The landscape change of the block streams are dominated by removal of weathered material from beneath of the valley rather than removal of bedrock blocks themselves.

• Journal of the Korean GEO-environmental Society
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• v.25 no.5
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• pp.29-37
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• 2024

This study aimed to investigate the changes in chemical components that occur when weak clay is mixed with steel slag modified with calcium oxide, and to understand the expression characteristics of compressive strength according to hydrophilicity and curing time. XRF testing, SEM imaging, vane shear strength and uniaxial compressive strength testing were conducted. Calcium (Ca) released from the steel slag increases the Ca content in clay by increasing the number of crystal particles and forming a coating layer known as calcium silicate hydrate (CaO-SiO₂-H₂O) through chemical reactions with SiO₂ and Al₂O₃ components. The weak clay stabilized with steel slag is classified into an initial inactive zone where strength relatively does not increase and an activation zone where strength increases over curing time. The vane shear strength of the initial inactive area was found to be 4.4 to 18.4 kN/m² in the state of the weight mixing ratio Rss 30% (steel slag 30% + clay 70%). In the case of the active area, the maximum uniaxial compressive strength increased to 431.8 kN/m² after 480 hours of curing time, which increased due to the apparent adhesion strength of clay through pozzolanic reaction. Therefore, considering the strength expression characteristics of stabilized mixed clay based on the mixing ratio (Rss) during the recycling of steel slag can enhance its practicality in civil engineering sites.

• Korean Journal of Ecology and Environment
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• v.34 no.1 s.93
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• pp.9-19
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• 2001

contrasting monsoon between 1993 and 1994 produced an interannual difference in hydrology. Theoretical water residence time (TWRT) in monsoon 1993 averaged 27 d, which was>3 months shorter compared to the TWRT in monsoon 1994. A dominant physical process influencing thermal stratification, water movement, and mixing regime was an interflow current in 1993. During summer 1993, river water plunged to mid-lake (location 27 km) and passed through the 10${\sim}$20m stratum of the reservoir, resulting in an isolation of epilimnetic lake water from advected river water. The interflow disrupted thermal stratification and produced a meta-hypolimnetic warming of >4$^{\circ}C$ downlake, thereby increased a mixing depth (>13 m). In contrast, during monsoon 1994 density currents were not observed and strong thermal stratification occurred in the entire reservoir, resulting in > 2 fold greater thermal resistance (8.2${\times}10^{5}$ erg)compared to 1993 (4.0${\times}10^{5}$ erg). This reservoir was identified as a typical warm monomictic reservoir which showed one mixis during early winter. The timing of overturn, however, differed between the two years as a result of distinct contrast in TWRT and thermal regime; overturn in 1993 occured about one month earlier relative to that in 1994. Hypolimnetic warming was predictable in this system; the variation in discharge accounted (Y = 4.35-0.06X+0.10X$^{2}$, p<0.0001)for 98% of the interannual variation in hypolimnetic temperature. Overall data suggest that thermal stability, the timing of fall overturn, and water residence time in this system are primarily regulated by the intensity of monsoon.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.33 no.1
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• pp.110-118
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• 2015

Borimsa Temple in Jangheung, one of the Goosanseonmoon of Shilla Dynasty, calls for a study in the field of landscape architecture because it has very significant elements in cultural and ecological landscaping aspects. This study examined the changes in landscaping elements of Borimsa Temple since the 17th century in order to newly recognize cultural landscaping value of space composition elements for traditional temple and to verify landscape architectural position. For research method, literatures such as Sajeonggi (事蹟記), Joongchanggi, a surveyed map by Fujishima Gaijiro in 1928 and Joseon Gojeogdobo (朝鮮古蹟圖譜) and modern documents including Borimsa Temple Precision Ground Survey Report and photographic records of National Archives of Korea and provincial governments were examined together with a field survey in order to trace changes in landscape elements such as buildings within the temple site, pond and temple forest. The results are as the following: First, for geographical locations of Borimsa Temple, it is located in an auspicious location and Shipyuknahansang and Cheonbul were placed in a supplementary purpose according to the contents of Bojoseonsatapbi. Compared to Namhwaseonsa Temple in China, it has a similar environmental composition but the fact that buildings were placed on platforms is a distinctive difference. Second, architectural landscape of Borimsa Temple went through the Japanese colonial era and Korean War and still going through changes today. Thus, there shall be some appropriate measures such as to establish an archive of past landscape data. Third, the contents of Borimsa Temple Sajeonggi suggests that the pond of Borimsa Temple had been in a indeterminate form with stones on the outer edge. Its name could have been Yongcheon (湧泉) according to the contents of Joongchanggi. Also, the current landscape, in comparison with past photographs, is a result of changes from surface raise occurred by ground reinforcement within the temple site. Fourth, Jangsaengpyoju (長生標柱) mentioned in Bojoseonsatapbi and Borimsa Temple Sajeonggi was thought to be the dried juniper tree in front of Daewoongbojeon, which can be found in past photographic documents but, it is now assumed to be Seokbihyeong (石碑形) considering the Gukjangsaeng and Hwangjangsaeng of Dogapsa Temple of the similar time period. Moreover, Hongsalmoon mentioned in Joongchanggi was established by King's order after the Manchu war of 1636 in praising of Buddhist monks those who had volunteered to fight for the country. Fifth, it is apparent in Borimsa Temple Joongchanggi that geomancy was a consideration in landscaping process of Borimsa Temple, and the record indicates that pine trees, bo trees and persimmon trees were planted. Sixth, tea tree forest was verified of its historical root that is Seongchailyeo from Unified Shilla through passing down of Jeong Yak-yong's Goojeunggoopo method and relevant documents of Seon Master Choui and Yi Yu-won. Seventh, nutmeg tree forest suggests that nutmegs were used in national ceremonies and for medical uses. The nutmeg tree forest was also verified of its role as Naehwasoorimdae (a forest built to prevent fire from spreading) through aerial photographs and placement of a forest reserve.

• The Journal of the Petrological Society of Korea
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• v.9 no.4
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• pp.238-253
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• 2000

In the eastern part of the Euiseong Basin acidic~intermediate volcanic rocks widely distribute on the Cretaceous sedimentary basement. Coeval granitic rocks and dyke rocks intruded into the volcanic rocks. Volcanic stratigraphy of study area are andesite lava, dacitic lapilli tuff, dacitic flow-banded lava, rhyolitic bedded tuff, rhyolitic massive tuff, dacitic massive lava, rhyolitlc welded tuff occur from the lower to the upper strata. $SiO_2$ content of the volcanic rocks range from 51 to 74 wt.%. With the increase of $SiO_2$, the contents of $TiO_2$, $Al_2$$O_3$, MgO, FeOT MnO, CaO, $P_2$$O_{5}$ decrease but those of $K_2$O increase. The contents of $Na_2$O show dispersive variation. This trend is quite sim-ilar to the major oxide variation in the volcanic rocks from the Yucheon sub-basin. The geochemical natures indicate that the volcanic rocks in the study area are discriminated to the island-arc type high K to medium K calc-alkaline rocks. The compositional variation of the volcanic rocks can be explained by the plagioclase fractionation of the volcanic magmas originated from similar source materials. The volcanic stratigraphy seems to have formed by at least two eruptive sequences of andesitic to rhyolitic and dacitic to rhyolitic magmas which underwent crystallization differentiation.