• Journal of the Korean Geotechnical Society
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• v.15 no.2
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• pp.105-127
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• 1999

Application of the soil nailing method is continuously extended in maintaining stable excavations and slopes. Occasionally, however, ground anchor support system may not be used because of space limitations in urban excavation sites nearby the existing structures. In this case, soil nailing system with relatively short length of nails could be efficiently adopted as an alternative method. The general soil nailing support system, however, may result in excessive deformations particularly in an excavation zone of the existing weak subsoils. Pretensioning the soil nails then, could play important roles in reducing deformations mainly in an upper part of the nailed-soil excavation system as well as improving local stability. In the present study, the analytical procedure and design technique are proposed to evaluate maximum pretension force and stability of the pretensioned soil nailing system. Also proposed are techniques to determine the required thickness of a shotcrete facing and to estimate probability of a failure against the punching shear. The predicted results are compared with the limited measurements obtained from the excavation site constructed by using the pretensioned soil nails. Based on the proposed procedure and technique, effects of the radius of a influence circle and dilatancy angle on the thickness of a shotcrete facing, bonded length and safety factors are analyzed. In addition, effects of the reduction of deformations expected by pretensioning of the soil nails are examined in detail throughout an illustrative example and FLAC$^{2D}$ program analysis.s.

• Journal of Environmental Policy
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• v.4 no.1
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• pp.1-19
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• 2005

On January 1, 2005, the Special Act on Metropolitan Air Quality Improvement, known as the Blue Sky 21 Program, entered into force. This Special Act is aimed at reducing the annual average concentrations of $PM_{10}$ and $NO_2$ to $40{\mu}g/m^3$ and 22ppb, respectively, from their current levels of $76{\mu}g/m^3$ and 36ppb, within the next 10 years. While the main focus of the Act is to reduce $PM_{10}$ and $NO_2$ emissions, the government also anticipates that these reductions would lessen high ozone occurrences and improve visibility. However, reducing local PM emissions would not decrease $PM_{10}$ concentrations as much as expected since other significant sources, such as continental inflow and/or secondary formation from photochemical reactions, exist. This is corroborated by the fact that $PM_{10}$ in the greater Seoul Metropolitan area during the ozone season is mostly in the form of $PM_{2.5}$, which is secondarily formed on a regional scale. Furthermore, many modeling results indicate so-called '$NO_x$ disbenefits,' referring to the fostering of an increase in ozone concentrations from a decrease in $NO_x$ emissions, over an extensive area. In this paper, the current status of air quality in the Seoul Metropolitan area is reviewed, and several other issues, including the effect of long-range transport, photochemical characteristics, and tasks for successful implementation of the Special Act are discussed.

• Journal of Navigation and Port Research
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• v.39 no.4
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• pp.285-291
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• 2015

Exposure to cold sea water can be life-threatening to the drowned individual. Although appropriate life jacket can be usually be provided for the buoyance at the drowning accident, heat loss can make the drowned individual experience the hypothermia. Inflatable life jackets filled with inflatable air pocket can increase the thermal protection as well as the buoyancy force. Because it is important to know how the human body behaves unde the different life jacket, present study compares the thermal insulation capacity of solid type life jacket with that of inflatable life jacket. In order to represent the insulation capacity of life jacket, thermal resistance is estimated based on the assumption of steady-state. Also, a transient three-dimensional thermal distribution of the thigh is analyzed by using finite element method implementing the Pennes bioheat equation. The finite element model is a segmental, multi-layered representation of the body section which considers the heat conduction within tissue, bone, fat and local blood flow rate.

• Journal of Wetlands Research
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• v.17 no.2
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• pp.163-175
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• 2015

In this paper, soil erosion and soil loss management system (SMS) of the City of Calgary in Albert, Canada was reviewed. Regulatory basis supporting this soil management system, permit process and conditions, guidelines and principles for the SMS, and monitoring and repair duties, inspection were discussed. Permit process in the City of Calgary is handled mainly by Urban Development Division, in which special task force called CPAG (Coorporative Planning Application Group) (if necessary circulated through related subdivisions). Inspects all the permit conditions and decides permit or refusal, and LUM (Land Use and Mobility) advertises the approval, if there is no appeals, permit is released to developers. If permit is rejected, applicant can appeals Development Appeal Board, it can approve or reject. In addition to permit, the city has manual for soil management plan, which includes BMP selection, design, monitoring, maintenance, and inspection activities. Perfect SMS policy does not necessarily guarantee relieving the soil-particle related pollution problem, but in Korea, we have to recognize that construction works during development is potentially the most destructive stage of environmental pollution. The central and local governments must make preparations for the effective and tight regulations and ordinance which is appropriate for regional social-economic conditions.

• Journal of Digital Convergence
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• v.17 no.11
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• pp.1-7
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• 2019

This study analyzed the effects of labor aging on labor productivity using panel statistics of 16 local governments from 1995 to 2017. The aging of the labor force, defined as the proportion of workers aged 60 or older in total employment, in the results of the panel regression analysis considering regional fixed effects and various adjustment variables, has a very consistent and significant negative effect on labor productivity. For every 1% increase in aging, labor productivity decreases by about 0.14 ~ 0.20%. In addition, the per capita capital stock and human capital considered as adjustment variables contributed to the increase of labor productivity, and the unemployment rate, which is a proxy variable of the economic fluctuation, has a significant negative effect on labor productivity as expected. The coefficient of the industrial structure, which represents the share of the service industry in the whole industry, was positive, but is not significant. The results of this study suggest that the design and construction of economic and educational policies that can maintain and expand human capital are necessary to curb the reduction in labor productivity expected by the aging workforce.

• The Journal of Natural Sciences
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• v.11 no.1
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• pp.119-130
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• 1999

As Japanese economy has been well developed, the manpower problem of farmland has also become one of the largest and the most crucial issues in the overall agricultural policy of the Japanese Government. Particularly, the energetic younger generation and a core of agricultural labor force, has drastically decreased, while the weak older generation has increased. The severity of manpower shortage in agricultural sector led to create a farmer training programs which had been vigorously begun by the Yamagata Prefecture, and a center for promoting local autonomy. The major purpose of education for enhancement of status of future farmers as well as the welfare of core farmhousehold is to provide them with technical of vocational education to give training to those who want to become agricultural technicians, rural leaders of practical farmers Educational program for future and young farmers put emphasis on practical trainings which are directly applied to proper farm management. As a supporting policy for promoting future farmers' activities, Prefecture-level supports were strengthened to develop technical capability, managerial and supervisory ability, and the ability to lead organized activity so that the farm youth may operate modern farms with higher efficiency and greater specialization. Political consideration was also made to develop a rich sense of farm management as well as the adaptability necessary to introduce technical and managerial innovations. Methological measurements on how the Korean government has to do for solving the problem of agricultural manpower facing in farmland in Korea were noted.

• (The) Research of the performance art and culture
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• no.18
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• pp.563-598
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• 2009

Gangneung Danoje is a local festival that has its origin in the county festival handed down premodern society. It was designated as an important intangible cultural asset in 1966, and has appreciated as a representative traditional festival of Korea since UNESCO designated it as 'the Oral and Intangible Heritage of Humanity' in 2005. Generally, it is known as a festival which it keeps up the premodern tradition. However, we can know that it is different from the festival performed in the 19 century in its framework and contents if we pay attention to the texts of festival performed in Gangneung today. I think that this change is a result of cultural adaptation by the change of transmission situation, and especially today texts of festival is an result of the pursuit, restoration and reproduction of its traditional form so as to be designated as a cultural asset. In this paper, after I have an accurate grasp of the traditional form of Gangneung Danoje from the present data related to Gangneung Danoje, I will compare its traditional text with the existing text which was reconstructed at the time of being designated as an important intangible cultural asset. To do this work, I verified the composition method of a county festival by investigating a general aspect of county festival in the $Chos{\breve{o}}n$ dynasty, brought out the aspect of its change by comparing its existing text with the procedures and contents of Gangneung Danoje before the Japanese occupation by force, and discussed the matter of its some changes. As a result of my work, I ascertained that the present Gangneung Danoje is very different from the festival transmitted in premodern society in the structure, time and space of festival, and the contents of performance containing the procedures of meeting god, seeing god off, and enjoying god.

• The korean journal of orthodontics
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• v.51 no.6
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• pp.366-374
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• 2021

Objective: This study investigated the impact of a single piezocision in the maxillary alveolar process on the speed of tooth movement. The null hypothesis was that the speed of tooth movement will be equal with and without piezocision. Methods: All maxillary molars on one side were moved against the combined incisors in 10 ten-week-old male Wistar rats. Under general anesthesia, a force of 25 cN was applied on either side using a Sentalloy closed coil spring. After placing the orthodontic appliance, vertical corticision was performed using a piezotome under local anesthesia, 2 mm mesial from the mesial root of the first molar on a randomly selected side; the other side served as the control. At the beginning of the treatment, and 2 and 4 weeks later, skull micro-computed tomography was performed. After image reconstruction, the distance between the mesial root of the first molar and the incisive canal, and the length of the mesial root of the first maxillary molar were measured. Moreover, the root resorption score was determined as described by Lu et al. Results: Significantly higher speed of tooth movement was observed on the corticision side; thus, the null hypothesis was rejected. The loss of root length and root resorption score were significantly more pronounced after piezocision than before. A strong correlation was observed between the speed of tooth movement and root resorption on the surgical side, but the control side only showed a weak correlation. Conclusions: Piezocision accelerates orthodontic tooth movement and causes increased root resorption.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.33 no.3
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• pp.93-100
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• 2021

Since the IB (Immersed Boundary) method, which can perform coupling analysis with objects and fluids having an impermeable boundary of arbitrary shape on a fixed grid system, has been developed, the IB method in various CFD models is increasing. The representative IB methods are the directing-forcing method and the ghost cell method. The directing-forcing type method numerically satisfies the boundary condition from the fluid force calculated at the boundary surface of the structure, and the ghost-cell type method is a computational method that satisfies the boundary condition through interpolation by placing a virtual cell inside the obstacle. These IB methods have a disadvantage in that the computational algorithm is complex. In this study, the simplified immersed boundary (SIB) method enables the analysis of temporary structures on a fixed grid system and is easy to expand to three proposed dimensions. The SIB method proposed in this study is based on a one-field model for immiscible two-phase fluid that assumes that the density function of each phase moves with the center of local mass. In addition, the volume-weighted average method using the density function of the solid was applied to handle moving solid structures, and the CIP method was applied to the advection calculation to prevent numerical diffusion. To examine the analysis performance of the proposed SIB method, a numerical simulation was performed on an object falling to the free water surface. The numerical analysis result reproduced the object falling to the free water surface well.

• Journal of the Society of Disaster Information
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• v.17 no.4
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• pp.882-889
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• 2021

Purpose: The purpose of this study was to improve fire safety in Gosiwon, a residential space for the low-income class. Method: Problems appearing in the process of fire occurrence and damage were verified once again. In addition, we would like to suggest improvement measures through systematic discussions on blind spots. Results: As a result of examining the risk of cool fire, the causes of fire occurred in various ways. In addition, the possibility of radiant heat due to heat accumulation due to narrow rooms inside the Gosiwon was high. Also, it was found that the possibility of fire spread was high due to clothing and household goods. It was reconfirmed that the poor internal structure of a narrow indoor space had a significant effect on the spread of fire and the scale of damage as it tried to accommodate as many people as possible inside. Conclusion: It is necessary to complete the installation as soon as possible for Gosiwon where the simple sprinkler is not installed. For this, a stronger driving force from the government and local governments is needed. In addition, it will be necessary to discuss how to improve the spatial and structural fire vulnerabilities that appear due to the structural characteristics of the Gosiwon.