• KSCE Journal of Civil and Environmental Engineering Research
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• v.38 no.2
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• pp.357-367
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• 2018

Recent earthquakes in Gyeongju and Pohang have raised interest in liquefaction in South Korea. Liquefaction, which is a phenomenon that excessive pore pressure is generated and the shear strength of soil is decreased by repeated loads such as earthquakes, causes severe problems such as ground subsidence and overturning of structures. Therefore, it is necessary to identify and prepare for the possibility of liquefaction in advance. In general, the possibility of liquefaction is quantitatively assessed using the Liquefaction Potential Index (LPI), but it takes a lot of time and effort for performing site response analysis which is essential for the liquefaction evaluation. In this study, a simple method to evaluate the liquefaction potential without executing the site response analysis in a downtown area with a lot of borehole data was proposed. In this simple method, the correlation between the average shear wave velocity of the target location ground and the LPI divided by thickness of liquefiable layer was established. And the applicable correlation equation for various rock outcrop accelerations were derived. Using the 104 boreholes information in Seoul, the correlation equation between LPI and the shear wave velocity (ground water level: 0m, 1m, 2m, 3m) is obtained and the possibility of liquefaction occurrence in Seoul and Gyeongju is evaluated. The applicability of the proposed simple method was verified by comparing the LPI values calculated from the correlation equation and the LPI values derived using the existing site response analysis. Finally, the distribution map of LPI calculated from the correlation was drawn using Kriging, a geostatistical technique.

• Korean Journal of Child Studies
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• v.1
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• pp.65-81
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• 1980

This study is aimed at investigating the compensatory education which was already implemented or is being implemented in the U.S.A. and Japan; and at studying the types of programs and their characteristics; and at sounding out the possibilities of the application of such programs in family and social conditions is Korea. In order to achieve the above mentioned objectives, the established items for the study are as follows: (1) Various types of early children's education (2) Programs of compensatory education for the disadvantaged Children (3) Head Start Program, Early Training Project and Montessori School (4) Integrated Preschool Programs (5) Day-Care Center for employed mothers We investigated the various compensatory education programs for the preschool children who are in economically, socially, culturally disadvantaged conditions. Head Start Programs were federally supported programs for preschool children and opened as summer programs in 1965 for the first time. The purpose of Head Start has been to give preschool children the kinds of experiences they need in preparation for school. The Head Start children were found to be significantly better prepared for school than the normal children. However, after six to eight months, their initial advantages had virtually. disappeared and then the simple problem with Head Start and other such programs was that little long-term good could be evidenced unless the high quality educational environment was maintained. Therefore, to solve this problem, three other programs were funded as part of the overall Head Start. These three programs are the Parent-Child Center, Home Start, and the Child and Family Resources Program. The Early Training Project for disadvantaged children was implemented by Klaus and Gray of Peabody College in 1962. The program was a field research study concerned with the development and testing over time of procedures for improving the educability of young children from low income homes. Its major concern was to study whether it was possible to offset the progressive retardation observed in the public schooling careers of children, living in deprived circumstances. Children, who were trained through the Early Training Project were superior to control groups in the test of IQ and vocabulary as well as linguistic abilities, and preparation for reading. This project showed the possibilities which could prevent preschool children from being disadvantaged socially, culturally and mentally. In 1907, Montessori School was established by Maria Montessori in Italy and her school program has been introduced at present to several countries in the world as one compensatory educations. She first began her experimental methods with retarded children, followed by disadvantaged children from the tenements of Rome. The Montessori approach futures a prepared environment and carefully designed, self-correcting materials. The Montessori curriculum presents tastes that feature sequence, order, and regularity, in addition to those that develop motor and sensory skills. She was interested in children's intellectual development and in developing good work habits. One of the latest developed programs for disadvantaged children is "Integrated Preschool Program" which has successfully integrated handicapped and nonhandicapped children. Several studies have showed that handicapped children in integrated school environments are accepted by and interact with their nonhandicapped peers. In fact, this program provides a number of potential, and perhaps opportunities for nonhandicapped children to serve as valuable resources in fostering the development of their handicapped peers. Next we turn to Japanese programs which are divided into two different types. One is Day-Care Center which was established by Child Welfare Law and the other is kindergarten organized by School Education Law. The kindergarten opened in 1876 and it has been part of school systems since 1947 by the implementation of education law, and the Day-Care Center which started in 1890 for the employed mothers. was changed into Day-Nursery by the enactment of child welfare law in 1947. The laws and operational regulations for the Day-Nursery were set up and were put in effect by the establishment standard acts of children welfare facilities, and the Day-Nursery has been operated in various types by the increasing demand, chiefly because of the socio-economical changes of family structures in both urban and suburban areas. Nursery education for physically and mentally disadvantaged children is for those who are blind, deaf and dumb, mentally retarded; physically disadvantaged by accidents or diseases. Montessori education in Japan was started in 1968 and many research groups for studying Montessori were organized. In 1977, Montessori remedial education society was also organized in which they started a number of studies; a study for developing materials; in-service training for the remedial education; and seminars and lectures, etc It is strongly suggested that we study the early educations that are being implemented in Japan and a variety of compensatory educations that were already implemented in the U.S.A. and modify them for the organization of our own model and properly accommodate them to our social needs.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.30 no.1
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• pp.146-158
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• 2012

This study aims to discussion the characteristics of location and spatial organization of the Seoul Sajikdan that has significance as one of national ceremonial place in Joseon Dynasty to understand its landscape architectural characteristics. To do this, we studied in two ways; review of historical documents and analysis of the present conditions and photographing, research materials about the form of physical structure. Through these ways, the results are as follows. First, in case of construction, Sajikdan took fundamental shape in Tae-jong 16 year(1416), since then it had been changed during Imjin War, reign of Suk-jong, and Japanese Colonial Era. It took present shape through restoration of Seoul Sajikdan in 1998. Second, in case of location, Sajikdan abuts onto southeastern range of Mt. Inwang that is Wubaekho(右白虎) of inner four mountain(內四山) of Hanyang, and it has a topography of west-high-east-low type. Also its territory is up to Maedong elementary school, the office of Sajik-dong, and a Dangun shrine. Third, in case of spatial organization, Sadan and Jikdan are in harmony of Yin-Yang(陰陽) and arranged in the center. As making Yumun and Sinmun(神門) at the center of four side of Yuwon and Juwon(周垣), they show organization of the Five Elements. And subsidiary buildings are thought that its arrangement was considered functional similarity and use convenience. Finally, in case of spatial component, Danyu structures are Sadan and Jikdan that hold a Sajikdaeje(社稷大祭), Yuwon that surround two altars, and Juwon that is outer fence of Yuwon. Architectures are Sajikdan Jeongmun, Sinsil, and Anhyangcheong. Also Prunus yedoensis, Zelkova serrata, Acer palmatum, are planted, but Pinus densiflora was main species and there needs to be replanted suitably to the site.

• Journal of Korean Tunnelling and Underground Space Association
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• v.21 no.1
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• pp.31-48
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• 2019

The artificial ground freezing (AGF) method is a groundwater cutoff and/or ground reinforcement method suitable for constructing underground structures in soft ground and urban areas. The AGF method conducts a freezing process by employing a refrigerant circulating through a set of embedded freezing pipes to form frozen walls serving as excavation supports and/or cutoff walls. However, thermal expansion of the pore water during freezing may cause excessive deformation of the ground. On the other hand, as the frozen soil is thawed after completion of the construction, mechanical characteristics of the thawed soil are changed due to the plastic deformation of the ground and the rearrangement of soil fabric. This paper performed a field experiment to evaluate the freezing rate of marine clay in the application of the AGF method. The field experiment was carried out by circulating liquid nitrogen, which is a cryogenic refrigerant, through one freezing pipe installed at a depth of 3.2 m in the ground. Also, a piezo-cone penetration test (CPTu) and a lateral load test (LLT) were performed on the marine clay before and after application of the AGF method to evaluate a change in strength and stiffness of it, which was induced by freezing-thawing. The experimental results indicate that about 11.9 tons of liquid nitrogen were consumed for 3.5 days to form a cylindrical frozen body with a volume of about $2.12m^3$. In addition, the strength and stiffness of the ground were reduced by 48.5% and 22.7%, respectively, after a freezing-thawing cycle.

• Journal of the Korean Institute of Landscape Architecture
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• v.47 no.1
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• pp.76-87
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• 2019

The purpose of this study was to evaluate the performance of and to derive future maintenance-management measures of the constructed alternative habitat for the Kaloula borealis at the University of Seoul, examining the period between 2015-2017. The research was constructed in 2014 and in a $191m^2$ area. The performance evaluation was divided into maintaining the habitat of the target species, maintaining the population and reproduction rates of the target species, maintaining the habitat of the wild species, the resilience of natural ecosystems, and the harmony with the surrounding environment. In terms of maintaining the habitat of the target species, soil collected from the existing habitat of the Kaloula borealis and was the depth was increased to 30cm in the alternative habitat. An artificial water supply was required every year during the supporting the spawning and hatching of other amphibians along with the Kaloula borealis. The sources of water of the alternative habitat were both rain and tap water, as it cannot be maintained naturally. Additionally, the Kaloula borealis thrived because it inhabited the research site and the average temperature was $26.2^{\circ}C$ from April-June, which is when the Kaloula borealis spawns. In terms of maintaining the population and reproduction rates of the Kaloula borealis, they were evaluated to have stable rates of reproduction. In terms of maintaining the habitat of the wild species, studies on vegetation and the structure of the characteristics of prey or predators will be needed. Also, alien species, such as Humulus japonicus and Bidens frondosa needed to be removed to maintain the wetland ecosystem of the wild species. In the assessment of the resilience of the natural ecosystems, the mud was monitored, noting the changes in the depth of water, with steps taken to reduce the leakage of water. The mud collected from the Haneul Pond wetland, which is located around the research site was piled up. Also, partial mowing management and the inducement of a natural vegetation colony was required for vegetation management. It was also necessary to create porous spaces, such as old trees and tree branches to create a habitat with hiding places and feeding and spawning places for small organisms. In terms of the harmony with the surrounding environment, the following threat factors needed to be managed: amphibian roadkill by vehicles and pedestrians and artificial draining due to nearby user access. Based on the monitoring results, alternative habitat management measures presented the promoting various waterside structures, in which amphibians can spawn and hide in, managing the water environment consistently, managing the vegetation, focused on the habitat of the wild species, and managing the surrounding environment for the habitat. The creation of an alternative habitat should be managed through monitoring, reflecting the characteristics of the changes in the site. Also continuing efforts are also needed to improve the habitat of the target species.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.29 no.4
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• pp.170-181
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• 2011

This Research will explore the meaning indicated in the landscape meaning and feature of literary group culture, focusing in Gurujeong(九老亭: pavilion for nine elders) and Samgaeseokmun(三溪石門: stone gate in three valleys) located in Dundeok-myun, Imshil-gun, and will seek to understand the implications by studying the cultural landscape spread out in the area. The place where Gurojeong and Samgaeseokmun is located is the meeting point of the three valleys, Dunnam stream, Osu stream, and Yul stream, which is the main location to view the beautiful scenery, which has the nickname as the dwelling place of a celestial being. Especially, based on the description of old maps, "Samgae(three valleys)" and "Samgaeseokmun" possesses significance as a landmark and shows a characteristic feature of landscape structures of low hills. Dangugurohwe(丹丘九老會: nine elders gathering on the dwelling of a celestial being) originated from Hyangsangurohwe(香山九老會: gathering of nine elders on a fragrant mountain), where Baekgeoi(白居易) of China was one of the main people. This group was organized by nine elders over the age of 60 desiring to view the scenery of Doyeonmyeong. The group enhanced the literary spirit on the low hill, erecting a tower, and enjoying the beautiful scenery changing every season with scholars from the same region. This phenomenon seems to have been formed upon the positive response to gatherings of elders, which were prevalent in the Joseon Dynasty. If the internal idea pursued by the group was "longevity," the external idea pursued can be summarized as "the spirit the respect for the elders." Naming the groups as 'Dangudae(place where the celestial being lives), Guseondong(valley of seeking a celestial life), Bangjangsan(mountain of a high priest), and Daecheondae(place of communicating with God) was likely a device to introspect oneself and symbolize one's life process. Furthermore, the reason Samgaeseokmun, which is an imitation of Choi, Chiwon's work, was built near Soyocheo, was probably to yearn the celestial land and based on the desire to follow Choi, Chiwon, who was the most self-fulfilling being presumed to have become a celestial being by practicing the pursuit of freedom, escaping from the reality. After tracing the symbolizing meaning of the four letters carved in the left side of the stone wall of Dangudae, the conclusion that this place was not only a place for literary gatherings of the nine elders of Saseong(four families), but was a place where the celestial being dwelled could be inferred. Corresponding with Dangudae and Gurojeong, which are places where the order of human and nature is harmonized and where its meaning associated with the location intensifies, arouses strong bond, can be said to be the symbol of the traces of celestial beings where the spirits of attachment to a certain place is embedded. The acts performed in Dangugurohwe were those of traditional leisure including strolling, viewing the scenery, drinking, composing poems, and playing instruments, and sometimes listening to stories, tea ceremony, prayers, and fishing were added, which indicates that the gathering had a strong tendency towards pastoral and hermit life.

• Korean Journal of Heritage: History & Science
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• v.55 no.1
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• pp.265-280
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• 2022

Hwangnyongsa Temple was the large Buddhist monastery of Silla that has existed for about 685 years. The temple underwent a series of excavations from 1976 to 1983, during which it was discovered that its layout consisted of one pagoda and three main dharma halls. This discovery also led to the production of four artistic depictions of the temple at various times from its foundation to its final phase. Previous studies on the architectural layout of Hwangnyongsa Temple are largely focused on the inner sanctuary ("Buddha's Land"). The studies on the temple's main architectural structures may be natural for those who are interested in the origins of and background to its establishment, but the studies on its outer sanctuary ("Sangha's Land") have to come first to acquire a deeper knowledge of the architectural layout of the temple as a whole. To gain a comprehensive understanding of the entire layout of Buddhist monasteries of the Silla dynasty, including both their inner and outer sanctuaries, the studies on Hwangnyongsa Temple are essential as it was once the kingdom's most highly honored temple. The studies on Korean Buddhist monasteries of the Three Kingdoms Period have produced only a limited amount of information concerning the outer sanctuary, resulting in little evidence about the exact scope of the temple's sanctuary. Meanwhile, the excavations of the Hwangnyongsa Temple site have revealed the archaeological features of the walls that divided the monastery and its neighboring facilities, thus helping to delineate the size of the temple site. The excavations have revealed the boundaries between the inner and outer sanctuaries of Hwangnyongsa Temple, as well as the entire temple precincts and the exterior, providing valuable information about the changes made to the layout of the temple. In this study, the main discussion focuses on the changes made to the sanctuary of Hwangnyongsa Temple during the Unified Silla and Goryeo Periods, particularly in relation to the architectural layout of the temple. The discussion is based on a review of the periods in which the Nammunji(South Gate site) was built, which provides tangible evidence about the expansion of the temple to the south, and the walls enclosing the temple precincts on the four sides and the changes that occurred afterwards. As a result, the study concludes that both the inner and outer sanctuaries of the temple probably changed through the 1 st and 3rd. It also concludes that the changes made to the architectural layout of Hwangnyongsa Temple were intended not only to alter the scope of the temple but were also closely associated with the politico-geographical significance of its location at the center of the royal capital of Silla and the urban archaeological remains around it.

• Journal of Korean Tunnelling and Underground Space Association
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• v.26 no.1
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• pp.59-78
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• 2024

In tunnel construction, the stability is evaluated by the settlement of adjacent structures and ground, but the shear strain of the ground is the main factor that determines the failure mechanism of the ground due to the tunnel excavation and the change of the operating load, and can be used to review the stability of the tunnel excavation and to calculate the reinforcement area. In this study, a twin tunnel excavation was simulated on a soft ground in an urban area through a laboratory model test to analyze the behavior of the twin tunnel excavation on the adjacent pile grouped foundation and adjacent ground. Both the displacement and the shear strain of ground were obtained using a close-range photogrammetry during laboratory model test. In addition, two-dimensional finite element numerical analysis was performed based on the model test. The results of a back-analysis showed that the maximum shear strain rate tends to decrease as the horizontal distance between the pillars of the twin tunnel and the vertical distance between the toe of the pile group and the crown of the tunnel were decreased. The impact of the second tunnel on the first tunnel and pile group was decreased as the horizontal distance between the pillars of the twin tunnel was increased. In addition, the vertical distance between the toe of the pile group and the crown of the tunnel had a relatively greater impact on the shear strain results than the horizontal distance of the pillars between the twin tunnels. According to the results of the close-range photogrammetry and numerical analysis, the settlement of adjacent pile group and adjacent ground was measured within the design criteria, but the shear strain of the ground was judged to be outside the range of small strain in all cases and required reinforcement.