• Journal of Korean Tunnelling and Underground Space Association
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• v.25 no.1
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• pp.13-26
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• 2023

Recently, as the development of underground spaces has become active due to rapid urbanization and population density, interest in the ground behavior according to the construction of underground spaces is increasing. In large cities with high population density and many buildings, ground subsidence has a great impact on structures and there may be a risk of collapse, so the analysis of ground behavior due to underground construction is essential. Previous studies have been conducted on the subsidence pattern of the surface and the deformation of the tunnel when constructing the tunnel, but analysis has rarely been conducted by using actual topographic information. Therefore, this study analyzed the difference in ground behavior between the actual topography and the flat topography. As a result, it was confirmed that ground settlement occurs at higher elevations, such as in mountainous topography, and when the numerical analysis is performed considering topographical information, the crown settlement of the tunnel is up to about approx. It showed a difference of 10 mm, and it was found that the sensitivity was less in the case of displacement of tunnel wall compared to the crown settlement and ground settlement. The numerical analysis considering the actual GIS-based topographic information presented in this study can be used to obtain more accurate surface subsidence data to understand the behavior of the upper structure due to tunnel excavation.

• Journal of the Korean Institute of Gas
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• v.22 no.6
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• pp.44-51
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• 2018

As the LNG storage tank is aged, if there is a crack in the outer wall concrete or corrosion of the reinforcing steel, there is a risk of a major accident such as collapse of the structure depending on the type and degree of damage. Since 2014, LNG storage tanks have undergone precise safety diagnosis and safety inspection has been carried out. The condition evaluation criteria for each component have been revised and applied in January 2016. The condition evaluation standard is to evaluate the status of storage tanks based on the appearance survey and material test results of LNG storage tanks and it is important for maintenance. In addition, the representative condition evaluation standard that shows the comprehensive state of each LNG storage tank is important in maintenance, but the related standard for LNG storage tank outer concrete is not available in Korea and abroad, and development of the condition evaluation standard is necessary. In this paper, we examined the structural characteristics of LNG storage tanks, analyzed the status of the condition evaluation criteria for each member, and developed a comprehensive status rating system by weighting the members. We used the AHP(Analytic Hierarchy Process) technique and developed a representative conditon evaluation criteria through surveys of professional organizations.

• Journal of Korean Society of Forest Science
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• v.107 no.4
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• pp.385-392
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• 2018

The slope stabilization analysis was performed by conducting survey and selecting the representative section in order to improve slope composition and management technology of masonry embankments in the quarry area, The mean slope of the masonry retain wall (A, B, C, D, E, F) was $38.5^{\circ}$, although the steep slope of the lowest slope (A) as $59^{\circ}$. The horizontal distance of the masonry embankments is 66.2 m and the slope height is 48.3 m. However, the inclination of the masonry embankments is relatively steep and visually unstable. The slope stability analysis for the slope stability analysis was taken into account during the drying and saturation. The slope stability analysis during saturation was performed by modeling the fully saturated slope. The strength constants of the ground were divided into two groups. The safety factor for dry period was 1.850 and the safety factor for rainy season was 1.333. The safety rate of dry period and rainy season was above 1.5 and 1.2. However, the weathered granite on the upper part of the masonry embankments at the time of heavy rainfall is considered to have a high risk of slope erosion and collapse. Therefore, it is considered necessary to take measures for stabilization through appropriate maintenance such as drainage installation.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.1
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• pp.33-40
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• 2021

In recent years, many construction projects become large and complicated, and construction accidents also steadily increase, which grows interest in the safety and maintenance during construction. Many of the construction accidents are related to temporary construction and structures, but the safety evaluation and management during construction are unclear and indefinite due to the short operating period and continuous change in the formation of the temporary structure. The system support, which is one of the temporary structures to support the pouring load of concrete, was proposed to easily install and dismantle members with connection parts pre-manufactured. The use of the system support is increasing to improve the safety of the temporary structure during construction. However, the system support, which consists of multiple members, still has uncertainties in connectivity between members and supports of vertical members. Therefore, this study analyzed the structure, load, and accident cases of the system support to define the damage scenarios for member connection, support condition, and lateral displacement. The decrease rate of the critical load was analyzed according to the damage scenarios based on the defined unit structure of the system support. In addition, this study provided vulnerable members for each damage scenario, which could induce instability of the temporary structures during design, construction, and operation of the structure.

• Journal of Korean Society of Archives and Records Management
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• v.19 no.3
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• pp.29-48
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• 2019

This study reviews the basics of earthquake preparedness from several archives and international cases of earthquake damage and restoration to establish an earthquake preparedness plan in Korean archives. The results of the study are as follows: first, to establish the direction of an earthquake preparedness plan, the study summarizes the basic characteristics of an earthquake and its damages, as well as applies the key elements of disaster preparedness planning after reviewing its basic principles. Second, the study analyzes four international cases that may have significant implications for the earthquake preparedness plan in Korea. Given this, four international cases present lessons and limitations such as the book dropping of a library in Japan, the collapse of archives in Germany, damaged archives because of a massive earthquake in New Zealand, and earthquake preparedness and recovery plans in cultural heritage sectors. Third, to apply the information from overseas cases to domestic, the study examines the lessons, the key elements of earthquake preparedness planning, and the public record standard for Korean archives through the mutual linking process, as well as issues that should be considered. The issues reviewed in this study could help Korean archives establish a realizable earthquake preparedness plan in the future.

• Journal of the Korean Institute of Gas
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• v.25 no.6
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• pp.35-44
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• 2021

The PR (Photo Resist) process in the semiconductor process is a process that uses a mixture of flammable substances. Due to the process equipment is installed in a clean room and when flammable substances leak, there is a high risk of suffocation, fire, and explosion. It is necessary to analyze the impact of accidents that may occur during operation and to evaluate whether the safety of workers can be guaranteed. In this study, the value of radiant heat and temperature change at the monitor point set up virtual inside the clean room was confirmed through CFD simulation of 10 leak and fire scenarios using the FLACS CFD - Fire Module. A fire that occurs inside a clean room transfers high radiant heat to the inter-story structure, but its scope is quite limited, and it is unlikely that it will collapse in a single fire accident. There was no scenario in which two stairs leading to the exit were exposed to high radiant heat at the same time due to a fire accident, therefore workers were able to escape in case of a fire. In addition, it was confirmed that the level of radiant heat and temperature rise rapidly decreased as they moved downstairs. According to the API 520 standard, workers exposed to 6.31 kW/m² of radiant heat that workers can withstand for 30 seconds were confirmed that it was possible to sufficiently escape from the inside.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.6
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• pp.182-192
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• 2023

In this study, the efficacy of Engineered Cementitious Composite(ECC) jacket for masonry fences subjected to lateral dynamic load was experimentally verified through a shaking table test, comparing it with the performance of an unreinforced masonry(URM) fence. Firstly, dominant frequencies, modal damping ratios and deformed shapes were identified through an impact hammer test. URM and ECC-strengthened fences with heights of 940mm and 970mm had natural frequencies of 6.4 and 35.3Hz, and first modal damping ratios of 7.0 and 5.3%, respectively. Secondly, a shaking table test was conducted in the out-of-plane direction, applying a historical earthquake, El Centro(1940) scaled from 25 to 300%. For the URM fence, flexural cracking occurred at the interface of brick and mortar joint(i.e., bed joint) at the ground motion scaled to 50%, and out-of-plane overturning failure followed during the subsequent test conducted at the ground motion scaled to 30%. On the other hand, the ECC-jacketed fence showed a robust performance without any crack or damage until the ground motion scaled to 300%. Finally, the base shear forces exerted upon the URM and ECC-jacketed fences by the ground motions scaled to 25~300% were evaluated and compared with the ones calculated according to the design code. In contrast to the collapse risk of the URM fence at the ground motion of 1,000-year return period, the ECC-jacketed fence was estimated to remain safe up to the 4,800-year return period ground motion.

• Korean Journal of Clinical Laboratory Science
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• v.39 no.2
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• pp.141-146
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• 2007

Obstructive Sleep Apnea-Hypopnea Syndrome (OSAHS) is a disorder characterized by the repetitive collapse of the pharyngeal airway during sleep, which leads to oxygen desaturation, sleep fragmentation, daytime sleepiness, and increased risk for hypertension and stroke. We investigated the clinical factors related to the severity of OSAHS. Polysomnography was performed in three hundred and ninety five consecutive adult patients with clinical symptoms of obstructive sleep apnea syndrome. All patients completed the sleep questionnaire and the Epworth Sleepiness Scale before polysomnography. Patients were classified into four groups based on the severity of their polysomnographic data: Non-OSA group, characterized by Apnea-Hypopnea Index (AHI) < 5; mild OSA group, by AHI 5-15; moderate OSA group, by AHI 16-30; and severe OSA group, by AHI > 30. Neck circumference was also measured at the cricothyroid level. A total of 395 patients (336 men and 59 women) were studied. In the non-OSA group, there were 55 patients; their mean neck circumference was $39.63{\pm}4.24cm$ and mean BMI was $24.48{\pm}3.53$. In the mild group, there were 101 patients; their mean neck circumference was $41.93{\pm}3.75cm$ and mean BMI was $25.33{\pm}2.94$. In the moderated group, there were 93 patients; their mean neck circumference was $43.27{\pm}3.50cm$ and BMI was $25.90{\pm}2.88$. In the severe group, there were 146 patients; their mean neck circumference was $44.94{\pm}3.93cm$ and mean BMI was $26.81{\pm}3.76$. Men had significantly larger neck circumference than women ($Mean{\pm}SD$, $43.72{\pm}3.83$ vs $39.17{\pm}4.30$, p < 0.001), and higher AHI than women ($29.12{\pm}22.65$ vs $14.63{\pm}14.11$, p < 0.001). Multiple regression analysis revealed that neck circumference was the most significant predictor of AHI. Neck circumference and BMI were positively correlated with the severity of OSAHS. The severity of OSAHS was greater in men than in women.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.12
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• pp.427-436
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• 2016

Due to disasters such as earthquakes and landslides in urban areas, persons have been buried inside collapsed buildings and structures. Rescuers have mainly utilized detection equipment by applying sound, video and electric waves, but these are expensive and due to the directional approaches onto the collapsed site, secondary collapse risk can arise. In addition, due to poor utilization of such equipment, new human detection technology with quick and high reliability has not been utilized. To address these issues, this study develops a wireless signal-based human detection module that can be loaded into an Unmanned Aerial Vehicle (UAV). The human detection module searches for the 3D location for buried persons by collecting Wi-Fi signal and barometer sensors data transmitted from the mobile phones. This module can gain diverse information from mobile phones for buried persons in real time. We present a development framework of the module that provides 3D location data with more reliable information by delivering the collected data into a local computer in the ground. This study verified the application feasibility of the developed module in a real collapsed area. Therefore, it is expected that these results can be used as a core technology for the quick detection of buried persons' location and for relieving them after disasters that induce building collapses.

• The Korean Journal of Franchise Management
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• v.2 no.2
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• pp.95-110
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• 2011

As global economic conditions are getting uneasy and polarization of our economy is intensified, the economic sentiment of small businesses is still low and unstable. The collapse of worldwide banking systems due to sub prime crisis in 2007 became the catalyst that shakes financial industries in each country in the world; the most sentiment people, small businesspersons, also have hard time facing survival way out, facing a great crisis. All organizing powers including manufactures, wholesales and retails are being gradually greater in mutual relations and dependence, and unstable factors about risks are also increasing. For exterior environmental and physical risk factors which cannot make small businesses survive themselves by developing ways out are eventually increasing, those who cannot cope with these factors face a great crisis. Although the government tries hard to overcome this situation conducting many ways, the effect does not continue. It is the real state that independent business markets including overall employment and establishing business have vicious cycle that they cannot be improved, due to increase of employment centered on short-term labors which lack durability in creation of employment and decline of household income. Recently, growth shows indication of slowdown because of multinational risk factors including financial crisis in each country in Europe, the death of Kim Jung-il, relationship with North Korea, and unstability of war situation in the Middle East Asia. Experts expect that growth rate will be about 4%, and independent business that ordinary people feel is still gloomy. It's reality that there is no adequate alternative for lack of jobs, unstable employment and a means of living after retirement. Also, the fact that large companies enter the market which is narrow and in the excessive competition should be an environmental factor that makes the situation worse. The business concept, a franchise, is the part we should think about whether it is the institutional solution that can guarantee independent businessmen stable life. Major companies are frightfully entering the market today, breaking the barrier to entry and shouting of a win-win with independent businesses. It's the small businesspersons who go through painful domestic recession, cannot predict the future and manage confusing and unstable independent business. It's very important to restore the domestic economy through wisely boosting consumption as soon as possible. It's also important to lead the situation by gathering powers of the government and related organizations, agonizing, suggesting solutions, and establishing accurate directions. The purpose of this study, therefore, is to suggest ways to strengthen competitiveness of small businesspersons by examining small business support policies which are currently implemented.