• Journal of the Korean Geotechnical Society
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• v.24 no.12
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• pp.5-12
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• 2008

The reinforced earth wall, which is able to improve the strength of soil highly, is required in case of supporting high surcharge load such as high speed rail way, high embankment road, and massive reinforced earth wall in a mountainous area. And also, it is continuously required that the method is able to minimize the amount of excavated soil on account of environmental issue, boundary of land, etc., on excavation site. However, because the required length of reinforcement should be $60{\sim}80%$ of the height of reinforced earth wall for general reinforced earth wall, in fact the reinforced earth wall is hardly applied on the site of cut slope. In this paper we studied the design and construction cases of hybrid reinforcement retaining wall system combined with steel strips and soil nails, connecting the reinforced earth wall reinforcements to the slope stability reinforcements (soil nails) to ensure sufficient resistance by means of reducing the length of reinforcements of reinforced earth wall. And the feasibility of hybrid reinforcement retaining wall system, suggested by real data measured on site, is also discussed.

• Journal of the Korean Geotechnical Society
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• v.39 no.7
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• pp.5-15
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• 2023

The evaluation of passive earth pressure plays a crucial role in the design of earth-retaining structures such as retaining walls and temporary earth-retaining walls to withstand horizontal earth pressure. In the earth pressure theory, active and passive earth pressures represent the earth pressures at the limit state, where the wall displacement reaches the maximum allowed displacement. In the design of earth-retaining structures, the passive earth pressure is considered as the resisting force. In this context, the limit displacement at which passive earth pressure occurs is significantly greater than that associated with the active earth pressure. Therefore, it is irrational to apply this displacement directly to the calculation of passive earth pressure. Instead, it is necessary to consider the mobilized passive earth pressure exerted at the allowable horizontal displacement to evaluate the structural stability. This study proposes an allowable wall displacement, denoted as 0.002 H (where H represents the excavation depth), based on a literature review that focuses on sandy soils. To calculate the mobilized passive earth pressure from the wall displacement, a semi-empirical equation is proposed. By analyzing the obtained data on mobilized passive earth pressure, a reduction factor applicable to Rankine's passive earth pressure is proposed for practical application in sandy soils under different wall movement types.

• Tunnel and Underground Space
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• v.33 no.6
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• pp.594-609
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• 2023

TBM (Tunnel Boring Machine) method is gaining popularity in urban and underwater tunneling projects due to its ability to ensure excavation face stability and minimize environmental impact. Among the prominent models for predicting disc cutter life, the NTNU model uses the Cutter Life Index(CLI) as a key parameter, but the complexity of testing procedures and rarity of equipment make measurement challenging. In this study, CLI was predicted using multiple linear regression analysis and tree-based machine learning techniques, utilizing rock properties. Through literature review, a database including rock uniaxial compressive strength, Brazilian tensile strength, equivalent quartz content, and Cerchar abrasivity index was built, and derived variables were added. The multiple linear regression analysis selected input variables based on statistical significance and multicollinearity, while the machine learning prediction model chose variables based on their importance. Dividing the data into 80% for training and 20% for testing, a comparative analysis of the predictive performance was conducted, and XGBoost was identified as the optimal model. The validity of the multiple linear regression and XGBoost models derived in this study was confirmed by comparing their predictive performance with prior research.

• Journal of Korean Tunnelling and Underground Space Association
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• v.24 no.5
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• pp.431-449
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• 2022

As many tunnels generally have been constructed, various experiences and techniques have been accumulated for tunnel design as well as tunnel construction. Hence, there are not a few cases that, for some usual tunnel design works, it is sufficient to perform the design by only modifying or supplementing previous similar design cases unless a tunnel has a unique structure or in geological conditions. In particular, for a tunnel blast design, it is reasonable to refer to previous similar design cases because the blast design in the stage of design is a preliminary design, considering that it is general to perform additional blast design through test blasts prior to the start of tunnel excavation. Meanwhile, entering the industry 4.0 era, artificial intelligence (AI) of which availability is surging across whole industry sector is broadly utilized to tunnel and blasting. For a drill and blast tunnel, AI is mainly applied for the estimation of blast vibration and rock mass classification, etc. however, there are few cases where it is applied to blast pattern design. Thus, this study attempts to automate tunnel blast design by means of machine learning, a branch of artificial intelligence. For this, the data related to a blast design was collected from 25 tunnel design reports for learning as well as 2 additional reports for the test, and from which 4 design parameters, i.e., rock mass class, road type and cross sectional area of upper section as well as bench section as input data as well as16 design elements, i.e., blast cut type, specific charge, the number of drill holes, and spacing and burden for each blast hole group, etc. as output. Based on this design data, three machine learning models, i.e., XGBoost, ANN, SVM, were tested and XGBoost was chosen as the best model and the results show a generally similar trend to an actual design when assumed design parameters were input. It is not enough yet to perform the whole blast design using the results from this study, however, it is planned that additional studies will be carried out to make it possible to put it to practical use after collecting more sufficient blast design data and supplementing detailed machine learning processes.

• Journal of the Speleological Society of Korea
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• no.68
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• pp.23-73
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• 2005

Purpose of study; The purpose of this study is specifically classified as two parts. The one is to attempt the chronological annals of Quaternary topographic surface through the study over the formation process of alluvial surfaces in our country, setting forth the alluvial surfaces lower-parts of Han River area, as the basic deposit, and comparing it to the marginal landform surfaces. The other is to attempt the classification of micro morphology based on the and condition premising the land use as a link for the regional development in the lower-parts of Han river area. Reasons why selected the Lower-parts of Han river area as study objects: 1. The change of river course in this area is very serve both in vertical and horizontal sides. With a situation it is very easy to know about the old geography related to the formation process of topography. 2. The component materials of gravel, sand, silt and clay are deposited in this area. Making it the available data, it is possible to consider about not oかy the formation process of topography but alsoon the development history to some extent. 3. The earthen vessel, a fossil shell fish, bone, cnarcoal and sea-weed are included in the alluvial deposition in this area. These can be also valuable data related to the chronological annals. 4. The bottom set conglometate beds is also included in the alluvial deposits. This can be also valuable data related to the research of geomorphological development. 5. Around of this area the medium landform surface, lower landform surface, pediment and basin, are existed, and these enable the comparison between the erosion surfaces and the alluvial surfaces. Approach : 1. Referring to the change of river beds, I have calculated the vertical and horizontal differences comparing the topographic map published in 1916 with that published in 1966 and through the field work 2. In classifying the landform, I have applied the method of micro morphological classification in accordance with the synthetic index based upon the land conditions, and furthermore used the classification method comparing the topographic map published in 1916 and in that of 1966. 3. I have accorded this classification with the classification by mapping through appliying the method of classification in the development history for the field work making the component materials as the available data. 4. I have used the component materials, which were picked up form the outcrop of 10 places and bored at 5 places, as the available data. 5. I have referred to Hydrological survey data of the ministry of Construction (since 1916) on the overflow of Han-river, and used geologic map of Seoul metropolitan area. Survey Data, and general map published in 1916 by the Japanese Army Survbey Dept., and map published in 1966 by the Construction Research Laboratory and ROK Army Survey Dept., respectively. Conclusion: 1. Classification of Morphology: I have added the historical consideration for development, making the component materials and fossil as the data, to the typical consideration in accordance with the map of summit level, reliefe and slope distribution. In connection with the erosion surface, I have divided into three classification such as high, medium and low-,level landform surfaces which were classified as high and low level landform surfaces in past. furthermore I have divided the low level landform surface two parts, namely upper-parts(200-300m) and bellow-parts(${\pm}100m$). Accordingly, we can recognize the three-parts of erosion surface including the medium level landform surface (500-600m) in this area. (see table 22). In condition with the alluvial surfaces I have classified as two landform surfaces (old and new) which was regarded as one face in past. Meamwhile, under the premise of land use, the synthetic, micro morphological classification based upon the land condition is as per the draw No. 19-1. This is the quite new method of classification which was at first attempted in this country. 2. I have learned that the change of river was most severe at seeing the river meandering rate from Dangjung-ni to Nanjido. As you seee the table and the vertical and horizontal change of river beds is justly proportionable to the river meandering rate. 3. It can be learned at seeing the analysis of component materials of alluvial deposits that the component from each other by areas, however, in the deposits relationship upper stream, and between upper parts and below parts I couldn't always find out the regular ones. 4. Having earthern vessel, shell bone, fossil charcoal and and seaweeds includen in the component materials such as gravel, clay, sand and silt in Dukso and Songpa deposits area. I have become to attempt the compilation of chronicle as yon see in the table 22. 5. In according to hearing of basemen excavation, the bottom set conglomerate beds of Dukso beds of Dukso-beds is 7m and Songpa-beds is 10m. In according to information of dredger it is approx. 20m in the down stream. 6. Making these two beds as the standard beds, I have compared it to other beds. 7 The coarse sand beds which is covering the clay-beds of Dukso-beds and Nanjidobeds is shown the existence of so-called erosion period which formed the gap among the alluvial deposits of stratum. The former has been proved by the sorting, bedding and roundness which was supplied by the main stream and later by the branch stream, respectively. 8. If the clay-beds of Dukeo-bed and Songpa-bed is called as being transgressive overlap, by the Eustatic movement after glacial age, the bottom set conglomerate beds shall be called as being regressive overlap at the holocene. This has the closest relationship with the basin formation movement of Seoul besides the Eustatic movement. 9. The silt-beds which is the main component of deposits of flood plain, is regarded as being deposited at the Holocene in the comb ceramic and plain pottery ages. This has the closest relationship with the change of river course and river beds.

• Korean Journal of Heritage: History & Science
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• v.50 no.3
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• pp.4-29
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• 2017

The purpose of this study is to grasp the commencement date of Korean-type bronze dagger through the chronology of Chinese data. It focuses on the fact that the same section polishing technique appears both in Korean type bronze dagger and Dongzhou type bronze dagger. Dongzhou type bronze dagger in Anqiu Shandong, in which A1 type section polishing technique is observed, was said to have been collected remains in 1958, but the clear excavation cannot be identified. Therefore, this study presents Tomb No.1 Zuojiawa Jinan, Dongzhou type bronze dagger, and associated products. As associated products, bronze weapon and bronze ware were excavated, whose periods are estimated to be in the Spring and Autumn period, the transition period of Warring States, and the former part of the China's Warring States. Accordingly, the Korean bronze dagger, excavated in the remains of the Han Peninsula appears to have run parallel with the Dongzhou type bronze dagger of the A1 type section polishing technique, excavated in China for a fixed period. In addition, the chronology of Tomb No. 61MI grave in Wanrongmiaoqian, Shanxi is estimated to range from the former part to the middle part of the China's Warring States, which is identified to be connected to the A1 type section polishing technique. Examining the data of the relative date, we can find out that the Commencement Period of the Korean type bronze dagger Culture is seen to be the transition period and the former part of the China's Warring States, which is estimated to be the 5th and 4th centuries BC. This chronology is followed by Tomb No.6512 Zhengjiawazi Shenyang, recorded as the 6th century B.C. which reveals that Liaoning type bronze dagger culture and Korean-typed Bronze Dagger Culture are naturally connected. Furthermore, the A1 type section polishing technique was distributed in the southwestern area of the Korean peninsula and Shandong, China, while the A2 type section polishing technique was distributed in the southern area of the Korean peninsula, Shanxi-Province in China, and Northern Kyushu region in Japan. Seen from the weapon-shaped bronze ware of the section polishing technique, Shanxi area(Central Plains area), China. the southwestern area of the Korean peninsula (northwest area), and Northern Kyushu region in Japan are set up as one traffic road(spreading route). This demonstrates that the section polishing technique emerged around the Han Peninsular, spreading the technique regionally.

• The Journal of Engineering Geology
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• v.9 no.2
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• pp.161-176
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• 1999

The objectives of this study are to analyze the changes of geo-surface topography in the Siwha embankment and the Ahsan city area by the image processing of Landsat Thematic Mapper data, and to estimate the reclaimed amount of the exposed tidal flat in the Siwha area using the GIS. False color composite, Tasseled cap, NVDI(normalized difference vegetation index), and supervised classification techniques were used to analyze the distribution of sediments and the aspect of topographical variations caused by artificial human actions. The total amount of the exposed tidal flat was estimated on the basis of the database snch as aerial photography, hydrographic chart, geological map, and scheme drawing in the Siwha area. The possible excavation regions for a seawall were predicted analyzing the supervised classification image of Landsat TM data. Tasseled cap images were used to observe the distribution of sediments. The difference of the NDVI images between spring and summer seasons indicates that deciduous and coniferous forests were distributed over the whole areas. The total fill-volume of the exposed Siwha tidal flat and the fill-volume of the construction planning seawall were calculated as $581,485,354\textrm{m}^3{\;}and{\;}3,387,360\textrm{m}^3$, respectively, from the digital terrain analysis. Daebu Island, Sunkam Island, and the part of Songsan-myeon were chosen as the cut area to make the seawall, and their cut-volumes were estimated as $5,229,576\textrm{m}^3,{\;}79,227,072\textrm{m}^3,{\;}and{\;}47,026,008\textrm{m}^3$, respectively. Therefore, the cut-volume of Daebu Island alone among three areas was sufficient to make the seawall.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.36 no.3
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• pp.149-159
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• 2018

The study is aimed at establishing basic data to identify the original forms of the garden in Unbo's House. Through interviews and related data comparison analysis the ideas and major events of the person involved in establishing a garden in Unbo's House. Also, derived the direct and indirect effects of these people on gardening. The results are as follows: First, Those directly related to garden in Unbo's House are representative figures of cultural heritage and traditional art in Korea. Based on their expertise and abundant experience in traditional spaces, they contributed greatly to the creation of Unbo's House as a traditional space. Unbo Kim, Gi-Chang who directly influenced Unbo's House gardening, which affected the site selection, location, and the installation of major garden plant plants and traditional landscaping facilities. Hyegok Choi, Soon-Woo recommended Wabon Kim, Dong-Hyun at the request of Kim Ki-Chang and was involved in the overall plan. Housing design, space design and design of major facilities such as pond were confirmed Wabon Kim Dong-Hyun. Second, Kim, Gi-Chang's wife Jeong, Rae-Hyun, who motived to construct a garden. Nosan Lee, Eun-Sang and Korean artist Lee, Seok-Ho were created a signboard and board of the Pillar to encourage simple life in paintings. The themes of the article motived image as creative. In addition, Kim, Hyeong-Sik and Kim, Wan who son of Unbo, has been with Unbo for a long time, watching and influencing garden changes in Unbo's House. Third, The main factors that influenced the garden by character are as follows. Unbo Kim, Ki-Chang had a thorough record-setting spirit and his longing for his mother and wife affected the selection of the site and setting the direction of the garden. His art world with the symbolic emphasis of traditional landscapes, including traditional facilities, and especially plant materials. Choi, Sun-Woo reflected his traditional consciousness and experience in the construction of Unbo's House. Kim, Dong-Hyun applied the basic framework of a traditional building based on Yeonkyongdang hall in Changdeokgung palace. He also reflected on the traditional landscaping design the facilities of ponds acquired through excavation of Donggung Palace and Wolji Pond, Gyeongju. Nosan Lee, Eun-Sang and Lee, Seok-Ho completed their unique place in Unbo's House. Kim, Hyung-Sik was involved in the process of changing, while Kim Wan ran the Unbo's House which he inherited from Kim, Ki-Chang.

• Korean Journal of Heritage: History & Science
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• v.50 no.4
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• pp.198-221
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• 2017

The Jjoksaem site is the eastern sector of Daereungwon Ancient Tomb Complex, Gyeongju(the 512th Historic site) called Wolseong North Burial Ground in academic community. The excavation and research of this site was conducted from 2007 to 2015, with the purpose of basic data offering for the restoration of Silla tumuli and development of ancient tomb park. As a result of the investigation, more than 700 new tombs were discovered except the 155 tumuli founded in the Japanese colonial era. Moreover, more than 70 percent of the smaller tombs, such as outer coffin tombs, were discovered here. There are four characteristics of outer coffin tombs in Jjoksaem site. First, it is recognized the Gyeongju-styled outer coffin tombs have a long rectangular shape, distinct from Gimhae-styled outer coffin tombs in a rectangular shape. Second, they are divided into three groups by the size of the grave area. This is indirectly related to the rank and the status of the buried person. Third, these tombs began to be constructed at the end of the 3rd century before the time of wooden chamber tombs covered by stone and earthen mound. They were ruined because of the new tombs constructed at the period of Maripgan. This reflects that the identity of the former tombs was not respected by the communities in the later generations. Outer coffin tombs were consistently made to the end of the era of wooden chamber tombs covered by stone and earthen mound. Lastly, the area of burial ground of outer coffin tombs is limited by wooden chamber tombs covered by stone and wooden mounds. Otherwise, the location of the burial ground for the deceased is limited by the status of the deceased. The idea that wooden chamber tombs covered by stone and earthen mound are located on the above ground turns out to be incorrect. In Jjoksaem site, there is little difference between the height of the circular burial protection stone and the height of the digging lines of the other tombs. In the case of No.44 tumulus, the lowest step of the circular burial protection stones is lower than those of the other tombs and tumuli. Research of outer coffin tombs at Jjoksaem site will be to suggest important academic data about the changing period from Saroguk, as the head of chiefdom union, to Silla, as state.

• Korean Journal of Heritage: History & Science
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• v.41 no.1
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• pp.109-125
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• 2008

Recently, there has been an increase in excavation studies of wood pagodas from the Three Kingdoms and Unified Shilla periods and new data related to wood pagoda erection are being found bringing about progress in research on this field. In other words, studies on wooden pagodas in Korea were composed mainly of flat, axis construction techniques and sarijangeomgu, but by acquiring new data, it has now become possible to study not only the stylobate construction procedure and transition, but also studies on restoring wooden pagodas. Furthermore, pagoda sites similar to this were found in China and Japan as well, making it possible to make comparative studies among ancient wooden pagodas possible. In this paper, the main remains were set as Baekjae wooden pagodas, which were the most frequently studied and among the wooden pagodas, the simcho (central base stone) and sarira housing locations. In result, simcho can be found changing its position from underground ${\rightarrow}$ halfway underground ${\rightarrow}$ above ground. Baekjae wooden pagodas up until the mid sixth century located at Neungsan-ri saji (AD 567) and Wangheungsaji (AD 577) had its simcho located underground and later it was constructed halfway underground and then above ground. It was confirmed that in the 7th century, it became customary to place above ground as seen in the Jaeseoksaji (AD639) and Hwangnyongsaji (AD645) wooden pagoda sites. The sarira was usually located on the south side of the simcho, but gradually changed to the center. In particular, sarira were combined in the simcho in the mid sixth century at the Wangheungsaji. This is approximately 11 years earlier than the Bijosa (AD 588) simcho found in Japan and this was not found even in the simcho of wooden pagodas in Yeongnyeongsa (AD 516) and Jopaengseong temple (AD 535~561) of China showing that the Wangheungsaji simcho was the earliest of its kind.