• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.3
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• pp.503-515
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• 2017

Underground structures that have recently become larger are required to be stable not only during normal times but also during earthquakes. Especially, it is very important to maintain the stability of the subsea tunnels during the earthquake. The objective of this paper is to verify the effectiveness of the flexible segment, which is one of the breakthrough facilities to maintain the stability of the subsea tunnel during the earthquake using the shaking table test. Another goal of this paper is to propose the optimum position of the flexible segment through 3D dynamic numerical analysis based on the verified results from shaking table tests. The 1g shaking table test considering the similarity ratio (1:100) to the cross section of the selected artificial subsea tunnel was carried out considering the Geongju and Artificial seismic waves, longitudinal and lateral wave, and with/without flexible segments eight times or more. As a result of the shaking table test, it was confirmed that the flexible segment is effective in improving the seismic performance of the undersea tunnel in all the experimental results. In addition, 3D dynamic numerical analysis was performed to select the optimum position of the flexible segment which is effective for improving seismic performance. As a result, it was confirmed that the seismic acceleration is attenuated when the flexible segment is installed adjacent to the branch section in subsea tunnel.

• Journal of Korean Tunnelling and Underground Space Association
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• v.15 no.3
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• pp.311-320
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• 2013

This paper presents the effect of Segment thickness during Shield TBM tunnelling in case study. In order to perform this study, the ground condition developed in the investigation site are reviewed and analysed. It is also carried out the construction problems occurred in the site during Shield TBM tunnelling. Several Segments were broken partially during advance tunnel by jacking pressure. The data surveyed from site are analysed in order to investigate the cause of Segment break. The numerical and analytical evaluations are carried out to examine the effect of Segment behaviour. From the results, it is found that the main causes of Segment break may be the jacking system and Segment thickness. In addition, new jacking technique is suggested to install safely the Segment during advance tunnel by jacking.

• Journal of Korean Tunnelling and Underground Space Association
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• v.16 no.1
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• pp.63-74
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• 2014

The lining of shield TBM tunnel is composed of segments, therefore segment joints are induced by connecting each segment. Segment joint is considered as joint stiffness in the design of TBM tunnel. Depending on the choice among the different stiffness equations, the joint stiffness values determined can be varied largely. Therefore, the influence of joint stiffness value on the design of segment lining should be verified. In this study, the joint stiffness values were determined firstly by using various equations and total change boundary was justified. Within the change boundary determined, the member forces were calculated by changing the joint stiffness through the numerical analysis and consequently the stability of segment lining was investigated by applying nominal strength. The results showed that the segment joint stiffness did not affect the design of segment lining largely.

• Fibers and Polymers
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• v.7 no.4
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• pp.367-371
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• 2006

Thermal properties of copolyetherester/silica nanocomposites were examined by using DSC and TGA. The segmented block copolyetheresters with various hard segment structures and hard segment contents (HSC) were synthesized and their silica nanocomposite films were prepared by solution casting method. The nano-sized fumed silica particles were found to act as a nucleating agent of the copolyetheresters. The nanocomposites always showed reduced degree of supercooling or faster crystallization than the corresponding copolyetheresters. The nanocomposites also showed increased hard segment crystallinity except HSC 35 sample which had short hard segment length. In case of 2GT [poly(ethylene terephthalate)] copolyetheresters, which were not developed commercially because of their low crystallization rate, the hard segment crystallinity increased considerably. The copolyetherester/silica nanocomposites showed better thermal stability than copolyetheresters.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.198-200
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• 2003

This study proved if the high resolution satellite imagery of IKONOS is suitable for preparing digital forest cover map. Three methods, the pixel based classification with maximum likelihood (PML), the segment based classification with majority principle(SMP), and the segment based classification with maximum likelihood(SML), were applied to classify and delimitate forest cover of IKONOS imagery taken in May 2000 in a forested area in the central Korea. The segment-based classification was more suitable for classifying and deliminating forest cover in Korea using IKONOS imagery. The digital forest cover map in which each class is delimitated in the form of a polygon can be prepared on the basis of the segment-based classification.

• The Korean Journal of Ecology
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• v.26 no.2
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• pp.75-81
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• 2003

This study was performed to prove if the high resolution satellite imagery of IKONOS is suitable for preparing digital vegetation map which is becoming increasingly important in ecological science. Seven classes for forest area and five classes for non-forest area were taken for classification. Three methods, such as the pixel based classification, the segment based classification with majority principle, and the segment based classification with maximum likelihood, were applied to classify IKONOS imagery taken in April 2000. As a whole, the segment based classification shows better performance in classifying the high resolution satellite imagery of IKONOS. Through the comparison of accuracies and kappa values of the above 3 classification methods, the segment based classification with maximum likelihood was proved to be the best suitable for preparing the vegetation map with the help of IKONOS imagery. This is true not only from the viewpoint of accuracy, but also for the purpose of preparing a polygon based vegetation map. On the basis of the segment based classification with the maximum likelihood, a digital vegetation map in which each vegetation class is delimitated in the form of a polygon could be prepared.

• Macromolecular Research
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• v.10 no.6
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• pp.365-368
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• 2002

Thermoplastic polyurethanes (TPUs) with different hard segment length has been prepared from a fixed molar ratio of poly(tetramethylene ether glycol), 4,4'-diphenylmethane diisocyanate, and 1,4-butanediol by different polymerization procedures. Results reveal that the on-set temperature of endotherms ( $T_{cc}$ ) due to the crystallization of hard segments by cooling the TPUs from melt and the peak temperature of endotherms due to the melting of hard segments ( $T_{mh}$ ) by heating the TPUs increased and levelled off with increasing the hard segment length of TPUs. It has also been observed that soft segment glass transition temperature ( $T_{gs}$ ) of TPU decreased slightly with increasing the hard segment length, which explains less mixing of soft segments and hard segments. In tensile measurement of TPUs, strain hardening is observed with increasing the hard segment length, which is attributed to the strain induced crystallization of soft segments.

• Textile Coloration and Finishing
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• v.5 no.4
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• pp.60-66
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• 1993

Aqueous polyurethane(PU) anionomer dispersions were prepared from isophorone diisocyanate (IPDI), polytetramethylene adipate glycol(PTAd) and dimethylol propionic acid(DMPA) as potential anionic centers. The effects of polyol molecular weight(Mn) on the state of dispersion, thermal, mechanical, and viscoelastic properties and swelling of emulsion cast film were determined. With increasing Mn of PTAd, particle size of emulsion and soft segment T$_{g}$ decreased, and solvent swell, emulsion viscosity, and hard segment $T_{g}$ increased. Tensile strength showed minimum with PTAd 1000, and elongation at break generally increased with the Mn of PTAd. These results were possibly nterpreted in terms of soft segment-hard segment phase separation and crystallization of high molecular weight PTAd.

• Korean Journal of Veterinary Research
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• v.32 no.3
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• pp.321-331
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• 1992

The regional distribution and relative frequency of gastrointestinal endocrine cells were studied immunohistochemically in the gastrointestinal mucosa and pancreas of the fresh water turtle. Ten kinds of endocrine cells were identified in the gastrointestinal tract. Cholecystokinin-8-, bovine pancreatic polypetide-and glucagon-immunoreactive cells were seen throughout the gastrointestinal tract, also among them cholecystokinin-8-immunoreactive cells were most predominant in segment III. Although gastrin- and gastrin/cholecystokinin-immunoreactive cells were found from segment III to VI and X, respectively, they were numerous in segment III. Somatostatin-immunoreactive cells were observed from segment I to VII. 5-hydroxytryptamine- immunoreactive cells were detected in segment I, III, VIII, IX and X. Human pancreatic polypeptide-immunoreactive cells were demonstrated in segment V, VI, VIII, IX and X. Insulin-immunoreactive cells were found from segment III to X except for segment VIII, but rare in segment VII. Neurotensin-immunoreactive cells were found to be restricted to segment VIII, IX and X. No porcine chromogranin-, substance P- and bombesin-immunoreactive cells were detected throughout the gastrointestinal tract of the fresh water turtle. Although typical mammalian pancreatic islets encapsulated by connective tissue were not present in this species, five kinds of endocrine cells-glucagon, insulin, somatostatin, bovine pancreatic polypeptide and 5-hydroxytryptamine-were found in forming small or large groups and scattered in the exocrine gland region. However porcine chromogranin- and motilin-immunoreactive cells could not be demonstrated in the pancreas.

• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.6
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• pp.905-913
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• 2017

To design segment lining, loads such as self weight, vertical load, horizontal load, ground reaction, water pressure, backfill grouting pressure et al. have to be considered. Earth pressure and water pressure are the major factor to design segment lining such as concrete strength, segment thickness and amount of rebar et al. To analysis earth pressure and water pressure acting on segment lining, filed monitoring and back analysis are performed in this study.