• Journal of the Korean Society for Railway
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• v.16 no.5
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• pp.386-393
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• 2013

In this study, the so-called repeated plate load bearing test (RPBT) used to get $E_{v2}$ values in order to check the degree of compaction of subgrade, and to get design parameters for determining the thickness of the trackbed foundation, is investigated. The test procedure of the RPBT method is scrutinized in detail. $E_{v2}$ values obtained from the field were verified in order to check the reliability of the test data. The $E_{v2}$ values obtained from high-speed rail construction sites were compared to converted modulus values obtained from resonant column (RC) test results. For these tests, medium-size samples composed of the same soils from the field were used after analyzing stress and strain levels existing in the soil below the repeated loading plates. Finite element analyses, using the PLAXIS and ABAQUS programs, were performed in order to investigate the impact of the strain influence coefficient. This was done by getting newly computed $I_z$ to get the precise strain level predicted on the subgrade surface in the full track structure; under wheel loading. It was verified that it is necessary to use precise loading steps to construct nonlinear load-settlement curves from RPBT in order to get correct $E_{v2}$ values at the proper strain levels.

• Journal of the Korean Geotechnical Society
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• v.21 no.9
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• pp.87-102
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• 2005

In the congested urban areas, tunnelling close to existing structures or services often occurs due to the lack of surface space so that tunnelling-induced ground movements may cause a serious damage to the adjacent structures. This study focused on the two dimensional laboratory model pile-soil-tunnelling interaction tests using a close range photogrammetric technique. Testing equipments and procedures were Introduced, particularly features of aluminium rods regarded as the frictional granular material. The experimental result showed that the photo imaging process by the VMS and EngVis programs proved to be a useful tool in measuring the pile tip movements during the tunnelling. Consequently, the normalised pile tip movement data for the influence zones can be generated by the laboratory model tests using the Photogrammetric technique. This study presents influence zones associated with the normalized pile tip settlements due to tunnelling in the cohesionless material. The influence zones were Identified by both a laboratory model test and a numerical analysis. The normalized pile tip movements from the model test were in good agreement with the numerical analysis result. The influence zones proposed in this study could be used to decide the reasonable location of tunnel construction in the planning stage. However, the scale of model pile and model tunnel sizes must be carefully adjusted as real ones for practical application considering the ground conditions at a given site.

• Geomechanics and Engineering
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• v.22 no.3
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• pp.197-206
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• 2020

Reutilization of solid waste such as Tire Derived Aggregate (TDA) and mixing it with soft soil for backfill material not only reduces the required volume of backfill soil (i.e., sand-mining procedures; reinforcement), but also preserves the environment from pollution by recycling. TDA is a widely-used material that has a good track record for improving sustainable construction. This paper attempted to investigate the performance of Kaolin-TDA mixtures as a backfill material underneath a strip footing and close to a retaining wall. For this purpose, different types of TDA i.e., powdery, shredded, small-size granular (1-4 mm) and large-size granular (5-8 mm), were mixed with Kaolin at 0, 20, 40, and 60% by weight. Static surcharge load with the rate of 10 kPa per min was applied on the strip footing until the failure of footing happened. The behaviour of samples K80-G (1-4 mm) 20 and K80-G (5-8 mm) 20 were identical to that of pure Kaolin, except that the maximum footing stress had grown by roughly three times (300-310 kPa). Therefore, it can be concluded that the total flexibility of the backfill and shear strength of the strip footing have been increased by adding the TDA. The results indicate that, a significant increase in the failure vertical stress of the footing is observed at the optimum mixture content. In addition, the TDA increases the elasticity behaviour of the backfill.

• Journal of the Korean GEO-environmental Society
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• v.18 no.12
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• pp.13-23
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• 2017

This paper discusses about the reinforcement materials and construction method in order to cope with roadbed settlement in operating railway. In Korea, concrete tracks have been introduced to urban railways, high-speed railways, and general railways, but some recently constructed concrete tracks have experienced roadbed settlements. Reinforcement of the railway roadbed is urgent task for safe operation of railway, but it is difficult to reinforce the roadbed and there are no case history of reinforcing railway roadbed under an operating railroad track. Therefore, in this study, the target performance level for roadbed reinforcement was determined, and infiltration and solidity injection efficiency were investigated for selected reinforcement materials. As a result of the study, it was found that the generally used reinforcement materials and methods for geotechnical works need to be improved for applying in railway roadbed reinforcement.

• Journal of Arbitration Studies
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• v.29 no.4
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• pp.33-55
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• 2019

This study is aimed at drawing up improvement measures in connection with the resolution of claims, one of the major constraints in revitalizing South-North Korean economic cooperation. To that end, we first looked at the structure of South-North Korean economic cooperation and the institutional status related to resolving the claims. Also we analyzed the current status of the claims in the process of promoting South-North Korean economic cooperation by companies and the provisions of the claims between the parties in order to derive any problems. Through these research results, we were able to identify directions and implications for efficient improvement of the causes of several South-North Korean economic cooperation claims. First, at the corporate level, there is a need to create specific details of a contract for resolving disputes and to add additional third-party coordination functions in the relevant clause of the contract in preparation for the occurrence of a dispute. In addition, it is necessary to seek ways to advance jointly with corporations in China and other third countries in order to secure stability. Second, the government should continue to discuss ways of promoting South-North Korean commercial arbitration with North Korea so that follow-up measures can be completed as soon as possible. In addition, a two-track strategy is suggested to provide a practical negotiation channel at the private level. Also it is necessary to be active in persuading North Korea to join the international arbitration treaty in preparation for the activation of full-fledged economic exchanges.

• Journal of the Korean Geotechnical Society
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• v.32 no.3
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• pp.5-13
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• 2016

Stability analysis was conducted to analyze the application of pile-supported embankment to concrete slab track on the soft ground in Korea. Pile efficiency and tension of geosynthetics in accordance with the hight of embankment and the depth of soft soil were carried out by theoretical and numerical methods. Theoretical method predicted more conservatively than the numerical method for all the cases presented herein. The settlement stability is satisfied to allowable criteria of high speed railway in Korea. The pile-supported embankment has great potential for application to soft ground condition.

• Journal of Power Electronics
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• v.17 no.6
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• pp.1587-1599
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• 2017

This paper proposes a real-time implementation of an optimal operation of a double stage grid connected wind power system incorporating an active power filter (APF). The system is used to supply the nonlinear loads with harmonics and reactive power compensation. On the generator side, a new adaptive neuro fuzzy inference system (ANFIS) based maximum power point tracking (MPPT) control is proposed to track the maximum wind power point regardless of wind speed fluctuations. Whereas on the grid side, a modified predictive current control (PCC) algorithm is used to control the APF, and allow to ensure both compensating harmonic currents and injecting the generated power into the grid. Also a type 2 fuzzy logic controller is used to control the DC-link capacitor in order to improve the dynamic response of the APF, and to ensure a well-smoothed DC-Link capacitor voltage. The gained benefits from these proposed control algorithms are the main contribution in this work. The proposed control scheme is implemented on a small-scale wind energy conversion system (WECS) controlled by a dSPACE 1104 card. Experimental results show that the proposed T2FLC maintains the DC-Link capacitor voltage within the limit for injecting the power into the grid. In addition, the PCC of the APF guarantees a flexible settlement of real power exchanges from the WECS to the grid with a high power factor operation.

• The Southeast Asian review
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• v.27 no.1
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• pp.1-52
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• 2017

This study aims to compare the state building process focusing on the founding presidents of South Korea, which was a colony of the defeated state of World War II and the Philippines, the colony of the victorious state. To this end, it compares the lives of the presidents, mainly the founding president of Korea Syngman Rhee and Manuel Quezon who led the autonomy of the Philippines and established the Commonwealth government, in the contexts of the state building process of the two countries. In each country, the leaders had to address the core tasks for founding the states in common. Firstly, after the independence or the acquisition of state autonomy, both countries adopted a constitution based on the presidential system with the strong authority of the presidents influenced by the United States. Secondly, the two countries after the independence were operated on the basis of anti-communism at the forefront of the Cold War. In addition, they also carried out land reform to bring the peasants into the system for supporting anti-communism. Lastly, the two countries also faced the same issues of liquidating the Japanese colonial legacies. Therefore the study examines the establishment of the constitution, settlement of anti-communism line, the land reform issues, and liquidation of Japanese colonialism or occupation in each country. The Philippines attained 'constitutional independence' in 1935 and experienced political development faster than any other post-colonial country in Asia. However, except for the establishment of the constitution, the early leaders were not able to address the principal issues for state building. As land reform failed, landowners became economically and politically dominant. The Philippines, where the modern citizen class has not arisen suffered from the political and economic recession. In Korea, despite the Korean War and division of the country, the founding president Syngman Rhee attempted to solve the tasks. As a result, he was able to lay the track of liberal democracy against communism and also settled Japanese colonial legacy as much as it was allowed. In particular, through land reform, he has laid the basis for the nation-state and economic development and has set up the girders of Korean economy by adopting the market economy system. Although there are merits and demerits, compared with the leaders of other countries especially with the Philippines, it is no doubt that Syngman Rhee has played an essential role in establishing the state as a founding president.