• Proceedings of the KSR Conference
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• 2009.05a
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• pp.1542-1549
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• 2009

The function of subgrade in the railway is to support track load on the subgrade as well as train load. Unlike the traditional railway, the uppermost subgrade layer in the Gyeongbu high speed railway was constructed as the reinforced road bed. The reinforced road bed comprises sub-ballast in the upper part and grade ballast in the lower part. The filling material such as soil and rocks in the subgrade can be settled by consolidation of original ground, compression due to self weight, plastic displacement due to train operation, and unequal settlement due to embankment material or improper compaction, therefore many efforts have been given for sufficient compaction and use of proper filling materials in the construction stage. The purpose of this study is to investigate the deformation state of subgrade in the Gyeongbu high speed railway. The investigation on the subgrade settlement was performed by choosing representative sections suspected to be settled based on the previous GPR test results and track maintenance history, measuring the settlement for some time period after installing settlement measuring instruments on and under the reinforced road bed. and analyzing the long-term subgrade settlement data from monitoring system which was installed at the construction stage of the high speed railway.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.8
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• pp.1-12
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• 2021

Altman's Z-score is used to measure a company's financial health and to predict the probability that a company will collapse within 2 years. It is proven to be very accurate to forecast bankruptcy in a wide variety of contexts and markets. The goal of this study is to use Altman's Z-score model to forecast insolvency in non-financial publicly traded enterprises. Non-financial firms are a significant industry in Malaysia, and current trends of consolidation and long-term government subsidies make assessing the financial health of such businesses critical not just for the owners, but also for other stakeholders. The sample of this study includes 84 listed companies in the Kuala Lumpur Stock Exchange. Of the 84 companies, 52 are considered high risk, and 32 are considered low-risk companies. Secondary data for the analysis was gathered from chosen companies' financial reports. The findings of this study show that the Altman model may be used to forecast a company's financial collapse. It dispelled any reservations about the model's legitimacy and the utility of applying it to predict the likelihood of bankruptcy in a company. The findings of this study have significant consequences for investors, creditors, and corporate management. Portfolio managers may make better selections by not investing in companies that have proved to be in danger of failing if they understand the variables that contribute to corporate distress.

• Journal of the Korean Geotechnical Society
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• v.24 no.8
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• pp.149-160
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• 2008

Offshore pile foundations are prone to lateral soil pressures resulting from embankment construction for the reclamation on deepwater soft clay. Since the 1990s, offshore reclamation has actively progressed in Korea, connecting with the development of Songdo newtown, Incheon newport, and Busan newport representatively. Special attention has been given to lateral soil-structure interaction problems related to passively-loaded offshore pile foundations. Based on a plane strain large deformation finite element (LDFE) approach, this paper presents the results of investigation into undrained (short-term) and drained (long-term) behavior of passively-loaded offshore pile foundations. This study examines the effects of major factors, such as soil profile, pile head boundary condition, magnitude of embankment load, and average degree of consolidation. The results allowed quantification of differences in the magnitude of lateral soil pressure acting on the piles between undrained and drained phases.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.31 no.2
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• pp.116-129
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• 2005

Distraction osteogenesis is a new bone formation technique. There is a advantage of the environmental adaptation when distraction force is applied to the gap between osteotomy lines. But it has a disadvantage of long-term wearing of the appliance and long consolidation period. Therefore we make an effort to reduce it and repair normal function. Extracellular matrix proteins have a function to control the cellular growth, migration, shape and metabolism. In these, hyaluronic acid is a member of polysaccharide glycosaminoglycans (GAGs) and has a important function as bone formation and osteoinduction property. Purpose : In this experimental study in rabbit mandibular distraction osteogenesis, we investigated the bone enhancing property of hyaluronic acid and the expression of extracellular proteins such as osteocalcin and osteonectin. Materials and Methods : The experimental study was carried out on 24 Korean male white rabbits (both mandibular body, n=48). Distraction group was divided to distraction experimental (A, n=16) and distraction control (B, n=16) by the application of hyaluronic acid (Hyruan, LGCI, Seoul, Korea). Normal control group (C, n=16) was only osteotomized. After 5 days latency, distraction devices were activated at a rate of 1.4 mm per day (0.7 mm every 12hours) for 3.5 days. Animals were sacrificed at postoperative 3, 7, 14, and 28 days. H&E stain and immunohistochemical stain was done on decalcified section. Additionally RT-PCR analysis was done for the identification of the expression of osteocalcin and osteonectin. Results : The bone formation in distraction experimental group was much more than that in distraction and normal control group at postoperative 28 days. In immunohistochemical stain, osteocalcin was enhanced at only postoperative 14 days, but osteonectin was not different at each post-operation days. In RT-PCR analysis, osteocalcin was not different at each post-operation days, but osteonectin was strongly expressed in distraction experimental group at postoperative 7 days. The expression of osteocalcin and osteonectin was elevated during the healing period. Conclusion : We found the good bone formation ability of hyaluronic acid in distraction osteogenesis through the immunohistochemistry and RTPCR analysis to osteocalcin and osteonectin, known as a bone formation marker. The application of hyaluronic acid in distraction osteogenesis is a method to reduce the consolidation period.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.29 no.3
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• pp.217-226
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• 2007

Purpose: Distraction osteogenesis is considered to take favorable effect on the TMJ and be beneficial to prevent the relapse after the mandibular advancement of Class II malocclusion patient. This is the report with literature review on the mandibular advancement in the patients showing preoperative condylar resorption and who need larger amount of advancement. Patients and method: Distraction osteogenesis using intraoral device was performed for three mandibular hypoplasia patients (one male and two females). All patients were adult over 18 years old. The patients showed condylar bony resorption preoperatively. The distraction was performed intraorally with modified SSRO. After 7 days of latency period, activation was performed at the rate of 1.0 mm/day with twice turn. The devices were removed after 4-8 month consolidation period. Results: Total advancement of mandible was average 13 mm. One patient showed openbite immediately after removal of distraction device. It took long time to guide the openbite with elastics. The comparison between cephalometries immediately after device removal and postoperative six month revealed average 3.4 mm relapse. This means that mandibular advancement with distraction osteogenesis needs overcorrection and elastic rehabilitation even after enough consolidation periods. Conclusion: Larger amount of mandibular advancement could be achieved with distraction osteogenesis in severe mandibular hypoplasia with condylar resorption. However, some relapse was found during the follow-up period and the over correction is considered to be needed. The effect of distraction osteogenesis seems to be investigated with long-term follow-up.

• Geotechnical Engineering
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• v.14 no.5
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• pp.129-142
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• 1998

This research is focused on the inducement of the constitutive equation considering the creep strain component and on the development of a finite element method program. The purpose of this research was to contribute to the design of construction structures or to the construction management in soft clay ground through predicting the long-term strain of construction structures reasonably bused on the above program. Modified Cam Clay model was adopted to describe the elastic-plastic behavior of clayey soil. And in the calculation of the creep sprain, the secondary coefficient of consolidation C. was applied for considering the volumetric creep element and the constants m, $\alpha$, A were rosed by the empirical creep equation proposed by Singh 8E Mitchell for considering the deviatoric creep element. To examine the reliability of the program which is developed in this study, the estimated values by this program were compared with the theoretical solution and the experimental results. And the applicability of the developed program was found to be reliable from the sensitive analysis of each parameters used in this study. According to the results obtained from the application of the program on the field measurement data, the estimated values by the program were found with be consistent with the actual values. And from the analysis of the displacement of embankments, the case of considering the creep behavior induced much fower errors than the case of neglecting it. But the results obtained from considering the volumetric creep behavior only were slightly underestimated the results from considering the deviator creep behavior showed the slightly overestimated values. Therefore, it remains the task of further studios to develop the laboratory test devices to obtain the reliable creep parameters, and to select the appropriate soil parameters, etc.

• Journal of the Korean Geosynthetics Society
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• v.13 no.1
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• pp.85-92
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• 2014

Structures that have constructed in soft clay might suffer from many issues related to consolidation settlement or lateral movement of soft-clay during long-term period. Therefore, it is important to establish proper design and construction processes related to site investigation, soil improvement, construction management, and so on. This case study focused on the construction of the rahmen structure supported by pile foundations. Especially, the structure in this case had been constructed without improving underlying soft clay and before constructing backfill embankment due to the limited construction time and the traffic connection of the old road crossing new highway. Therefore, in order to satisfy the structural stability, the construction processes and countermeasure methods were carefully planned based on the results of preliminary numerical analyses and monitoring of ground behaviors. Through the trial and error precess during the construction, the structures had been successfully constructed.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.1046-1053
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• 2006

In the large scale recent reclaiming works performed within the wide spatial boundary, evaluation of long-term consolidation settlement and residual settlement of the whole construction area is sometimes made with the results of the limited ground investigation and measurement. Then the reliability of evaluation has limitations due to the spatial uncertainty. Additionally, in case of large scale deep excavation works such as urban subway construction, there are a lot of hazardous elements to threaten the safety of underground pipes or adjacent structures. Therefore it is necessary to introduce a damage prediction system of adjacent structures and others. For the more accurate analysis of monitoring information in the wide spatial boundary works and large scale urban deep excavations, it is necessary to perform statistical and spatial analysis considering the geographical spatial effect of ground and monitoring information in stead of using diagrammatization method based on a time-series data expression that is traditionally used. And also it is necessary that enormous ground information and measurement data, digital maps are accumulated in a database, and they are controlled in a integrating system. On the abovementioned point of view, we developed Geomonitor 2.0, an Internet based real time monitoring program with a new concept by adding GIS and geo-statistical analysis method to the existing real time integrated measurement system that is already developed and under useful use. The new program enables the spatial analysis and database of monitoring data and ground information, and helps the construction- related persons make a quick and accurate decision for the economical and safe construction.

• Journal of the Korean Geosynthetics Society
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• v.7 no.1
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• pp.39-44
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• 2008

Recently, the demand for industrial and residential lands are being increased with economic growth, however, it is difficult to acquire the land for development with good ground condition. For efficient and balanced development of land, new development projects are being carried out not only the areas with inland but those with the soft ground as well. As soft grounds have complex engineering properties and high variations such as ground settlement especially when their strength is low and depth is deep, it needs to accurately analyze the engineering properties of soft grounds and find general measurement for stabilization and economic design and management. Prefabricated vertical drain technology is widely used to accelerate the consolidation of soft clay deposits and dredged soil under the preloading and various types of vertical drain are being used with the discharge capacity. Under field conditions, the discharge capacity is changed with various reason, such as soil condition, confinement pressure, long-term clogging and folding of vertical drains, and so on. Therefore, many researcher and engineer recommend the use of required discharge capacity. In this paper, the experimental study were carried out for two different types of vertical drains by utilizing the large-scale model tests and waste lime.

• Journal of the Korean Geosynthetics Society
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• v.6 no.2
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• pp.1-8
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• 2007

Recently, the demand for industrial and residental land are increasing with economic growth, but it is difficult to acquire areas for development with good ground condition. For efficient and balanced development of land, new development projects are being carried out not only the areas with inland but those with the soft ground as well. As soft grounds have complex engineering properties and high variations such as ground subsidence especially when their strength is low and depth is deep, we need to accurately analyze the engineering properties of soft grounds and find general measures for stable and economic design and management. Vertical drain technology is widely used to accelerate the consolidation of soft clay deposits & dredged soil under pre-loading and various types of vertical drain are used with there discharge capacity. Under field conditions, discharge capacity is changed with various reason, such as soil condition, confinement pressure, long-term clogging and folding of vertical drains and so on. Therefore, many researcher and engineer recommend the use of required discharge capacity. In this paper, the experiment study were carried out to obtain the discharge capacity of four different types of vertical drains by utilizing the large-scale model tests and the required discharge capacity was calculated by several methods.