• Journal of Korean Tunnelling and Underground Space Association
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• v.11 no.1
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• pp.1-9
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• 2009

When a rock slope is excavated adjacent to a existing tunnel, the behavior of the existing tunnel in the jointed rock masses is greatly influenced by the joint conditions and slope status. In this study, the effects of joint dip and slope angle close to a tunnel are investigated through a large scale model using a biaxial test equipment ($3.1\;m\;{\times}\;3.1\;m\;{\times}\;0.50\;m$ (width $\times$ height $\times$ length)). The jointed rock masses were built by concrete blocks. The diameter of the modeled tunnel is 0.6 m and the dip angles of joint vary in the range of $0-90^{\circ}$. In addition, the excavated slope angle varies within $30{\sim}90^{\circ}$. Deformational behaviors of the tunnel were analyzed in consideration of joint dip and slope angle. With increase of the joint dip and slope angle, the magnitude of tunnel distortion and the moment of tunnel lining were increased. Rock mass displacement in horizontal was also dependent on the joint dip and the excavated slope angle, which indicated the optimal slope reinforcement for a specific rock mass conditions.

• Journal of Korean Tunnelling and Underground Space Association
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• v.25 no.6
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• pp.479-493
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• 2023

The need for safety management has arisen due to the increasing number of years of operated underground structures, such as tunnels and utility tunnels, and accidents caused by those aging infrastructures. However, in the case of privately managed underground utility ducts, there is a lack of detailed guidelines for facility safety and maintenance, resulting in inadequate safety management. Furthermore, the absence of basic design information and the limited space for safety assessments make applying currently used non-destructive testing methods challenging. Therefore, this study suggests non-destructive inspection methods using ultrasonic and impact-echo techniques to assess the quality of underground structures. Thickness, presence of rebars, depth of rebars, and the presence and depth of internal defects are assessed to provide fundamental data for the safety assessment of box-type general underground structures. To validate the proposed methodology, different conditions of concrete specimens are designed and cured to simulate actual field conditions. Applying ultrasonic and impact signals and collecting data through multi-channel accelerometers determine the thickness of the simulated specimens, the depth of embedded rebar, and the extent of defects. The predicted results are well agreed upon compared with actual measurements. The proposed methodology is expected to contribute to developing safety diagnostic methods applicable to general underground structures in practical field conditions.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.36 no.2
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• pp.50-60
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• 2024

To promote the application of reliability-based design within the Korean coastal engineering community, the author conducted reliability analyses and optimized the design of a vertical-type breakwater, considering multiple limit states in the seas off of Pusan and Gunsan - two representative ports in Korea. In this process, rather than relying on design waves of a specific return period, the author intentionally avoided such constraints. Instead, the author characterized the uncertainties associated with wave force, lift force, and overturning moment - key factors significantly influencing the integrity of a vertical-type breakwater. This characterization was achieved by employing a probabilistic model derived from the frequency analysis results of long-term in-situ wave data. The limit state of the vertical-type breakwater encompassed sliding, overturning, and collapse failure, with the close interrelation between wave force, lift force, and moment described using the Nataf joint probability distribution. Simulation results indicate, as expected, that considering only sliding failure underestimates the failure probability. Furthermore, it was shown that the failure probability of vertical-type breakwaters cannot be consistently secured using design waves with a specific return period. In contrast, breakwaters optimally designed to meet the reliability index requirement of 𝛽-3.5 to 4 consistently achieve a consistent failure probability across all sea areas.

• Journal of the Korean Geographical Society
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• v.42 no.4
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• pp.526-539
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• 2007

The purpose of this study is to investigate the influence of the Korean Wave on Chinese tourism to South Korea through a behavioral analysis of Chinese tourists in the general group package tours. China suppressed the needs of the Chinese people's geographical movement and imposed restrictions on information about the outside world with the use of a policy of "closure" for a long time. But since reforms and open-door policies were introduced in China, especially in the context of relaxation of control policies over Chinese outbound tourism after the mid-1990's, more and more Chinese make trips abroad including visits to South Korea. In this situation, the recent Korean Wave(especially, drama/film) describes the Korean national image by forming a bridge between fiction and reality and plays a pivotal role in broadening or reconstructing the geographical imagination of the Chinese people who have been historically isolated from the outside world. Although Chinese have imagined the Korean nationscape on the basis of geopolitical or economic factors in the past, they have currently broadened or reconstructed their geographical imagination to include socio-cultural factors related closely to the Korean way of life due to the recent Korean Wave. This newly constructed geographical imagination led by the Korean Wave functions as an important pulling factor in Chinese destination choices, affecting Chinese tourists' motivation formation and the recommendation of main attractions. The more influential the Korean Wave is on their destination choice, the more the respondents select the cultural factors in both their motivation for tourism to South Korea and their recommendations of tourism attractions to other people. Through the analysis results of both satisfaction and intention to revisit, the more influential the Korean Wave is on their destination choice, the higher is the degree of both satisfaction and intention to revisit. In other words, although Chinese tourism to South Korea is chiefly in the general group package tours, Chinese tourists who are influenced by Korean Wave on their destination choice have more attachment to(or affection for) Korea as a tourism destination. This result suggests that the Korean Wave affects qualitative change - that is, change of attitude - as well as quantitative change in Chinese demand for tourism to South Korea.

• Journal of the Korean Geographical Society
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• v.42 no.4
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• pp.540-559
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• 2007

The purpose of this paper is to analyse the locations and to interpret the landscapes of the local towns in Joseon Dynasty from Feng-shui's point of view. As a result of analysing the locations of towns in Gyeongsang Province, the towns which have typical Feng-shui landscapes make up to 58% of the total. Historically, the local towns that were established in the early period of the Joseon Dynasty didn't reveal Feng-shui's landscape, but those that were established in the late period of the Joseon Dynasty revealed the Feng-shui's landscape clearly. In this article, I classify the local towns of the Gyeongsang Province into 3 types: 1. Non Feng-shui type These towns are located near the seashore. The main reason that these towns were located at the seashore was defense against an enemy. 2. Semi Feng-shui type. These towns don't have natural location but have a man-made landscape, based on the principles of Feng-shui. 3. Typical Feng-shui type. These towns were typically administrational towns which were located at the center of a local region.

• Journal of Korean Tunnelling and Underground Space Association
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• v.23 no.4
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• pp.233-252
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• 2021

This paper is a study to improve the efficiency of mixing technology in the shield TBM chamber. Currently, the number of construction cases using the TBM method is increasing in Korea. According to the increasing use of TBM method, research on TBM method such as Disc Cutter, Cutter bit, and Segment also shows an increasing trend. However, there is little research on the mixing efficiency in chamber and chamber. In order to improve the smooth soil treatment and the behavior of the excavated soil, a study was conducted on the change of the mixing efficiency according to the effective mixing bar arrangement in the chamber. In the scale model experiment, the ground was composed using plastic materials of different colors for ease of identification. In addition, the mixing bar arrangement was different and classified into 4 cases, and the particle size distribution was classified into single particle size and multiple particle size, and the experiment was conducted with a total of 8 cases. The rotation speed of the cutter head of all cases was the same as 5 RPM, and the experiment time was also carried out in the same condition, 1 minute and 30 seconds. In order to check the mixing efficiency, samples at the upper, middle (left or right), and lower positions of each case were collected and analyzed. As a result of the scaled-down model experiment, the mixing efficiency of Case 4 and Case 4-1 increased compared to Case 1 and Case 1-1, which are actually used. Accordingly, it is expected that the mixing efficiency can be increased by changing the arrangement of the mixing bar in the chamber, and it is considered to be effective in saving air as the mixing efficiency increases. Therefore, this study is considered to be an important indicator for the use of shield TBM in Korea.

• Journal of Korean Tunnelling and Underground Space Association
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• v.2 no.2
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• pp.11-21
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• 2000

Tunnelling has been created as a great extent in view of less land space available because the growth of population in metropolitan has been accelerated at a faster pace than the development of the cities. In tunnelling, it is often faced that measures are obliged to be taken without confirmation for such abnormality as diverged movement of surrounding rock mass, growing crack of shotcrete and yielding of rockbolts. In this case, it is usually said that the judgments of experienced engineers for the selection of measure are importance and allowed us to get over the situations in many construction sites. But decrease of such experienced engineers need us to develop the new system to assist the selection of measures for the abnormality without any experiences of similar tunnelling sites. In this study, After a lot of tunnelling reinforcement methods were surveyed and the detail application were studied, an expert system was developed to predict the safety of tunnel and choose proper tunnel reinforcement system using fuzzy quantification theory and fuzzy inference rule based on tunnel information database. The expert system developed in this study have two main parts named pre-module and post-module. Pre-module decides tunnel information imput items based on the tunnel face mapping information which can be easily obtained in-situ site. Then, using fuzzy quantification theory II, fuzzy membership function is composed and tunnel safety level is inferred through this membership function. The comparison result between the predicted reinforcement system level and measured ones was very similar. In-situ data were obtained in three tunnel sites including subway tunnel under Han river. This system will be very helpful to make the most of in-situ data and suggest proper applicability of tunnel reinforcement system developing more resonable tunnel support method from dependance of some experienced experts for the absent of guide.