• Membrane Journal
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• v.30 no.6
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• pp.385-394
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• 2020

In the gas separation process, the separation membranes have to not only show high gas transport and selectivity but also exhibit exceptional stability at high temperature and pressure. However, when the polymeric membranes (particularly, glassy polymers) are exposed to the condensable gases (i.e., CO2, H2S, hydrocarbon, etc.), the polymer chains are prone to swell, leading to low stability. As a result, the plasticization behavior reduces the gas selectivity in the separation of mixture gases at high pressures and thus results in limited applications to the separation processes. To address these issues, many strategies have been studied such as thermal treatment, polymer blending, thermally rearrangement, mixed-matrix membranes, cross-linking, etc. In this review, we will understand the plasticization behavior and suggest potential methods based on the previously reported studies.

• Journal of Korean Tunnelling and Underground Space Association
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• v.24 no.6
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• pp.451-464
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• 2022

The high-level nuclear waste repository is a deep geological disposal system exposed to complex environmental conditions such as high temperature, radiation, and ground-water due to handling spent nuclear fuel. Continuous exposure can lead to cracking and deterioration of the structure over time. On the other hand, the high-level nuclear waste repository requires an ultra-long life expectancy. Thus long-term structural health monitoring is essential. Various sensors such as an accelerometer, earth pressure gauge, and displacement meter can be used to monitor the health of a structure, and a piezoelectric sensor is generally used. Therefore, it is necessary to develop a highly durable sensor based on the durability assessment of the piezoelectric sensor. This study designed an accelerated life test for durability assessment and life prediction of the piezoelectric sensor. Based on the literature review, the number of accelerated stress levels for a single stress factor, and the number of samples for each level were selected. The failure mode and mechanism of the piezoelectric sensor that can occur in the environmental conditions of the high-level waste repository were analyzed. In addition, two methods were proposed to investigate the maximum harsh condition for the temperature stress factor. The reliable operating limit of the piezoelectric sensor was derived, and a reasonable accelerated stress level was set for the accelerated life test. The suggested methods contain economical and practical ideas and can be widely used in designing accelerated life tests of piezoelectric sensors.

• The Journal of the Korea Contents Association
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• v.17 no.10
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• pp.559-566
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• 2017

Despite the government operating various preventive programs to ward off accidents and diseases on business sites, diseases rates are not decreasing, unlike accident rates. In many cases, diseases caused by work have a latent period before symptoms appear or progress over a longer term, making it difficult for workers to prove the causal relation between their work and the diseases. Moreover, data related to the business site are mostly owned by the employer. Even if the employee has access to parts of such data, his lack of medical expertise limits his ability to identify the characteristics of the diseases and how it appears. In August, 2017 the Supreme Court did an about-face with its ruling on the case involving diseases caused by exposure to harmful substances in work environments, by easing the burden of proof on the employees. As such, this study focuses on the case to analyze cases involving diseases that have occurred in work environments and present their implications. In doing so, the study seeks to provide a basic set of data that can help secure the employees' labor rights and rights to health by complementing the current law in relation to recognizing industrial incidents caused by rare diseases and making work environments safer for employees.

• Journal of fish pathology
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• v.21 no.1
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• pp.35-43
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• 2008

Pathological symptoms and hematological parameters of red sea bream, Pagrus major and water temperature in the culture ground was investigated to clarlify the cause of winter moratility. Dead fish showed green liver and accumulation of ascites in the cavity. A few Bivagina tai were also found on the gill but either bacteria or virus were not. When hematological parameters from fish taken before/after the winter mortality were compared, blood glucose, serum AST and ALT, and total cholesterol, trigyceride and total protein were significantly decreased in the fish after the winter mortality. These results may explain that the nutritional level of fish was decreased because fish could not fed during winter season. According to the CORI monitoring system operating by KODC, NFRDI a long term water temperature from Dec. 25, 2005 to Feb. 24, 2006 (60 days) were exposed the low water temperature environments to the red sea bream. First of all, mass mortality began at Sarayngdo where low temperature below 8℃ continued for 42 days. The winter mortality did not occured in the depths of 9 m to 19.2 m where difference of water temperature in the surface and bottom was only within 0.1℃. But in the depth of 7.5 m to 11 m winter mortality occured where water temperature in the surface and bottom showed much variation ranged from 0.2℃ to 1.4℃. From these results, great difference of water temperature in the surface and bottom of the culturing area might results in winter mortality of red sea bream.

• Journal of the Korean Geotechnical Society
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• v.39 no.10
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• pp.49-55
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• 2023

The discovery of lunar ice in the lunar polar region has fueled international interest in in situ resource utilization (ISRU) and the construction of lunar habitats. Unlike Earth's atmosphere, the Moon presents unique challenges, including frequent meteoroid impacts, direct exposure to space radiation, and extreme temperature variations. To safeguard lunar habitats from these threats, the construction of a protective shield is essential. Lunar regolith, as a construction material, offers distinct advantages, reducing transportation costs and ensuring a sustainable supply of raw materials. Moreover, it streamlines manufacturing, integration schedules, and enables easy repairs and modifications without Earth resupply. Adjusting the shield's thickness within the habitat's structural limits remains feasible as lunar conditions evolve. Although extensive research on protective shields using lunar regolith has been conducted, unresolved conflicts persist regarding shield requirements. This study conducts a comprehensive analysis of the primary lunar threats and suggests a minimum shield thickness of 2 m using lunar regolith. Furthermore, it outlines the necessary technology for the rapid construction of such protective shields.

• Proceedings of the Korean Society for Rock Mechanics Conference
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• 2000.09a
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• pp.183-193
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• 2000

A series of studies such as geological logging data analysis, detailed geological survey, rock mass evaluation, in-situ and laboratory tests, rock strength and mechanical properties of the rock were concerned. The stability of the slope were carried out inorder to design the pit slope and individual benches using the stereographic projection analysis and numerical methods in Roto Pit of Pasir coal fetid. The bedding plane was one of the major discontinuities in the Roto Pit and the dip of which is about $60^{\circ}$in the northern part and $83^{\circ}$in the southern part. The dip of bedding becomes steeper from north to south. The plane and toppling failures are presented in many slopes. In laboratory test the average uniaxial compressive strength of mudstone was 9 MPa and that of weak sandstone was 10 MPa. In-situ test showed that the rocks of Roto north mining area are mostly weak enough to be classified in grade from R2(weak) to R3(medium strong weak) and the coal is classified in grades from R1(Very weak) to R2(Weak). The detailed stability analysis were carried out on 4 areas of Roto north(east, west, south and north), and 2 areas of Roto south(east and west). In this paper, the minimum factor of safety was set to 1.2 which is a general criterion for open pit mines. Using the stereographic projection analysis and the limit equilibrium method, slope angles were calculated as 30~$36^{\circ}$for a factor of safety greater than 1.2. Then these results were re-evaluated by numerical analysis using FLAC. The final slope angles were determined by rational described abode. A final slope of 34 degrees can guarantee the stability for the eastern part of the Roto north area, 33 degrees for the western part, 35 degrees for the northern part and 35 degrees for the southern part. For the Roto south area, 36 degrees was suggested for both sides of the pit. Once the pit slope is designed based on the stability analysis and the safety measures. the stability of 니ope should be checked periodically during the mining operations. Because the slope face will be exposed long time to the rain fall, a study such aspreventive measures against weathering and erosion is highly recommended to be implemented.

• Tunnel and Underground Space
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• v.10 no.3
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• pp.430-440
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• 2000

A series of studies such as geological logging data analysis, detailed geological survey, rock mass evaluation, in-situ and laboratory tests, rock strength and mechanical properties of the rock were concerned. The stability of the slope were carried out inorder to design the pit slope and individual benches using the stereographic projection analysis and numerical methods in Roto Pit of Pasir coal field. The bedding plane was one of the major discontinuities in the Roto Pit and the dip of which is about 60$^{\circ}$ in the northern part and 83$^{\circ}$ in the southern part. The dip of bedding becomes steeper from north to south. The plane and toppling failures are presented in many slopes. In laboratory test the average uniaxial compressive strength of mudstone was 9MPa and that of weak sandstone was 10MPa. In-situ test showed that the rocks of Roto north mining area are mostly weak enough to be classified in grade from R2(weak) to R3(medium strong weak) and the coal is classified in grades from R1(Very weak) to R2(Weak). The detailed stability analysis were carried out on 4 areas of Roto north (east, west, south and north), and 2 areas of Roto south(east and west). In this paper, the minimum factor of safety was set to 1.2 which is a general criterion for open pit mines. Using the stereographic projection analysis and the limit equilibrium method, slope angles were calculated as 30∼36$^{\circ}$ for a factor of safety greater than 1.2. Then these results were re-evaluated by numerical analysis using FLAC. The final slope angles were determined by rational described above. A final slope of 34 degrees can guarantee the stability for the eastern part of the Roto north area, 33 degrees for the western part, 35 degrees for the northern part and 35 degrees for the southern part. For the Roto south area, 36 degrees was suggested for both sides of the pit. Once the pit slope is designed based on the stability analysis and the safety measures, the stability of slope should be checked periodically during the mining operations. Because the slope face will be exposed long time to the rain fall, a study such aspreventive measures against weathering and erosion is highly recommended to be implemented.

• Journal of Bio-Environment Control
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• v.3 no.2
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• pp.106-118
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• 1994

This study was conducted to analyze the effects of fluctuations in temperature, light intensity and soil temperature on the growth of red pepper seedlings in the nonheated plastic houses with various number of layers and in the open field. Relationship between the optimal environment and the growth of seedlings was discussed, and the maximum and minimum outdoor temperatures in Kwangju area from 1941 to 1985 were analyzed. The results obtained were as follows; 1. The minimum temperature in tunnel with quadruple coverings of P. E. film from December 20 to February 25 was decreased to 5$^{\circ}C$ mostly, where the exposure to chilling temperature could not be avoided during this period. The maximum temperature was increased to 33$^{\circ}C$ mostly and 42$^{\circ}C$ in peak, where some ventilation was needed. 2. The diurnal differences of inside temperature, increasing with number of layers, were 16 to 38$^{\circ}C$, while those of outside temperature were 5 to 1$0^{\circ}C$. 3. The cold injury in the quadruple coverings during winter occurred all the times below 12$^{\circ}C$ and as many as 200 times over 3$0^{\circ}C$, while effectiveness of thermal insulation in the multilayered nonheating plastic houses were clearly proved. 4. The inside light intensity was markedly reduced with the increment of layers and the minimum light intensity fallen down below the light compensation point for the growth of red pepper plants regardless of the number of layers. 5. Until 10 a. m., the temperature in the daytime during December 20 to mid - February showed below 10 to 12$^{\circ}C$ which was the limiting temperature for the growth of red pepper seedlings. After 4 p. m., the light intensity was sharply reduced despite of the air temperature kept over 12$^{\circ}C$. Therefore, limiting factors for the growth of red pepper seedlings were the temperature before 10 a. m. and the light intensity after 4 p. m. 6. The minimum soil temperature in quadruple coverings showed around 1$0^{\circ}C$ where the physiological damage for red pepper seedlings might be occurred. 7. The minimum outdoor temperatures from 1941 to 1985 was -19.4$^{\circ}C$, observed in the 5th January.

• Journal of the Korean association of regional geographers
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• v.22 no.1
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• pp.151-167
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• 2016

Conventional social science typically regards the idea of a 'mountain' as part of 'nature' and a physical environment existing separately from, or prior to, human society and culture. However, in Korea, which is 70% mountainous land, the 'mountain' is part of a unique 'social nature'. This research develops the idea that in this context the mountain is a social nature and a cultural landscape which are tied heavily to the idea of travel. The article interrogates why the scenic beauties of Mt. Kumgang have been perceived and conveyed through multiple generations since the Chosun Dynasty period. Focusing on Mt. Kumgang, this article illustrates how strongly people have held dreams of mountain travel, for the whole life-time. Travel writings(or accounts of trips to the mountain) and artwork have played a particularly important role in creating Mt. Kumgang's reputation as the most beautiful mountain in the country. At the same time, the access to the mountain was often a dangerous adventure, with many travelers facing hunger and extreme physical challenges. As portrayed in writings and artwork, the overall effect of these dynamics was the creation of a socionatural place of striking beauty that even seemed to have mystical or magical fantasy. According to Confucian ideals, full appreciation of nature and its beauty was key to understanding the logics of the universe and to achieving a high moral standard, which contributed to decide to leave for the mountain as well. The essays, poems, and paintings of Mt. Kumgang since the Chosun Dynasty period that portrayed the mountain's beauty collectively served to produce the mountain as a socionatural landscape engendered with potent place-myths, important historical meaning, and strong aesthetic associations. Thus, the travel to the mountain seemed never completed over until travelers had completed various artistic representations to record and to memorize what they'd done and seen in Mt. Kumgang, which had been performed for the strong purpose of social sharing of the real the mountain's beauties and itinerary.

• Korean Journal of Remote Sensing
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• v.37 no.5_2
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• pp.1329-1340
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• 2021

The intertidal zone, which is a transitional zone between the ocean and the land, requires continuous monitoring as various changes occur rapidly due to artificial activity and natural disturbance. Monitoring of coastal topography changes using remote sensing method is evaluated to be effective in overcoming the limitations of intertidal zone accessibility and observing long-term topographic changes in intertidal zone. Most of the existing coastal topographic monitoring studies using remote sensing were conducted through high spatial resolution images such as Landsat and Sentinel. This study extracted the waterline using the NDWI from the GOCI-II (Geostationary Ocean Color Satellite-II) data, identified the changes in the intertidal area in Gyeonggi Bay according to various tidal heights, and examined the utility of DEM generation and topography altitude change observation over a short period of time. GOCI-II (249 scenes), Sentinel-2A/B (39 scenes), Landsat 8 OLI (7 scenes) images were obtained around Gyeonggi Bay from October 8, 2020 to August 16, 2021. If generating intertidal area DEM, Sentinel and Landsat images required at least 3 months to 1 year of data collection, but the GOCI-II satellite was able to generate intertidal area DEM in Gyeonggi Bay using only one day of data according to tidal heights, and the topography altitude was also observed through exposure frequency. When observing coastal topography changes using the GOCI-II satellite, it would be a good idea to detect topography changes early through a short cycle and to accurately interpolate and utilize insufficient spatial resolutions using multi-remote sensing data of high resolution. Based on the above results, it is expected that it will be possible to quickly provide information necessary for the latest topographic map and coastal management of the Korean Peninsula by expanding the research area and developing technologies that can be automatically analyzed and detected.