• Imaging Science in Dentistry
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• v.39 no.1
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• pp.19-25
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• 2009

Purpose: To longitudinally observe the healing process of extracted socket and the alterations of the residual ridge in healthy adult dogs using cone beam CT (CBCT). Materials and Methods: The mandibular premolars of two beagle dogs were removed and the extraction sites were covered with the gingival tissue. CBCTs (3D X-ray CT scanner, Alphard vega, Asahi Co.) were taken at baseline and at 1 week interval for 12 weeks. Radiographic density of extracted wounds was measured on normalized images with a custom-made image analysis program. The amount of alveolar crestal resorption after the teeth extraction was measured with a reformatted three-dimensional image using CBCT. Bony healing pattern of extracted wound of each group was also longitudinally observed and analyzed. Results: Dimensional changes occurred during the first 6 weeks following the extraction of dogs' mandibular premolars. The reduction of the height of residual ridge was more pronounced at the buccal than at the lingual aspect of the extraction socket. Radiographic density of extracted wounds increased by week 4, but the change in density stabilized after week 6. New bone formation was observed at the floor and the peripheral side of extracted socket from week 1. The entrance of extracted socket was sealed by a hard-tissue bridge at week 5. Conclusion: The healing process of extracted wound involved a series of events including new bone formation and residual ridge resorption.

• Explosives and Blasting
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• v.25 no.2
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• pp.71-78
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• 2007

In many cases of underwater blasting in South Korea, the special blasting is mainly used for deepening harbor, installing gas pipes, or well blasting to build a bridge. The procedure of well blasting is almost same with shaft blasting, but the difference is that water is filled in before blasting. In case of deepening blasting under water, the first step like drilling, arranging explosives, and wire connection is done on a barge, then the next step such as charging and tamping is accomplished under water by expert divers. Therefore, underwater blasting needs precise and exact plan before blasting. In this paper, authors would like to introduce a case of underwater blasting for deepening the Busan new port with emulsion explosives and non-electric detonators in order to get some of 8,500TEU out sized container vessels entered into the port and to make safe. Considering environment and vibration, the blasting was controlled to minimized the damage to the lighthouse nearby. It will be great help to many other blasting sites where emulsion explosives and non-electric detonators are used for underwater blasting through this case.

• Archives of Reconstructive Microsurgery
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• v.13 no.1
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• pp.1-6
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• 2004

Advances in microvascular techniques and refinements in microsurgical tissue transfers have enabled surgeons to combine different tissue components and reconstruction into a single-stage operation in extensive or composite defect following injury. Some problems and consideration for extensive or composite defects are form, shape, function, and dimension of the defect sites. Therefore combination of two or more flaps is required to reconstruct extensive or composite defect. This paper presents our clinical experience of four cases of combined free flaps with or without sequential microanastomosis in reconstruction of upper extremity based on peroneal flowthrough, thoracodorsal, and dorsalis pedis vascular system. Satisfactory results were obtained without flap loss and complications. The free flaps were combined in th following fashion; two cases by bridge fashion, one by chimeric microanastomosis and one by simple chimeric fashion. The median follow-up time on all patients was 21.7 months. Donor site morbidity was minimal. Extensive soft tissue or composite defects can be effectively covered by various combined flaps. Even though the risk for complication exists, the options of combination with or without sequential microanastomosis can add a functional or sensory dimension to reconstruction of complex wounds.

• Journal of Korean Society on Water Environment
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• v.31 no.5
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• pp.460-467
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• 2015

We analyzed the formation of phytoplankton community and the occurences of odorus compound from benthic cyanobacteria in North, South Han-River, Paldang-Lake and Kyeongan-Stream sediments. Sediments were incubated in different water temperature. Akinetes were found (0~500 cells/g) with the highest number on sediment in Yangsoo railroad bridge (YC). The result showed that Anabaena ranged between $0.02{\sim}0.53{\times}10^3cells/mL$ in Sambong (SB), YC, Mukhyen-Stream (MS), Paldang-Lake (P2) and Kyeongan-Stream (KK). The total 68 taxa of phytoplankton were observed during the incubation period. A standing crop of phytoplankton was in the range of $0.13{\sim}8.97{\times}10^3cells/mL$ and Microcystis appeared in SB, YC, P2 and KK sites with $20{\sim}25^{\circ}C$ temperature. In South Han-River (P3), Oscillatoria tenuis was dominant at $25^{\circ}C$ temperature. The concentration of geosmin was the highest in SB-$15^{\circ}C$ (25.5 ng/L), and the concentration of 2-MIB was the highest in P3-$25^{\circ}C$ (286.8 ng/L). Odorous compounds were detected in all the temperature conditions from each site. Our results indicate that the dominant benthic cyanobacteria (O. tenuis, O. limosa, Phormidium tenue and Pseudanabaena limnetica) have high correlation with the occurrence odorous compounds and 2-MIB.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.2
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• pp.397-407
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• 2013

Recently, a great progress has been made in bridge construction technology through the development of high performance materials and new structural types. However, most of attention has been paid to the cast-in-place technologies and material cost saving. The cast-in-place method is always subject to some environmental damages in construction sites, which frequently causes conflicts with residents. To overcome the disadvantages, a lot of fabrication construction method was developed. Most fabrication construction methods developed up to now have been applied for superstructure of bridges. In contrast, such fabricable methods developed for substructures are extremely rare. A fabricated column using ICH CFT(Internally Confined Hollow CFT) column was developed in a series of previous researches. Included in the previous studies are design and construction methods for the precast segmental coping, the column-coping connection, the column-segment connection, column-foundation connection. In this paper, seismic performance of the fabricated ICH CFT columns was extensively investigated experimentally. Two test specimens were prepared depending on the connection methods of segments; one by mortar-grouting method and the other by reinforcement method using stiffeners.

• Geomechanics and Engineering
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• v.10 no.5
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• pp.677-687
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• 2016

Industrialization and urbanization are the two phenomena that are going relentless all over the world. The consequence of this economic success has been a massive increase in waste on one hand and increasing demand for suitable sites for construction on the other. Owing to the surplus raw materials and energy requirement needed for manufacturing synthetic fibers, applications of waste fibers for reinforcing soils evidenced to offer economic and environmental benefits. The main objective of the proposed work is to explore the possibilities of improving the strength of soil using fly ash waste as an admixture and Human Hair Fiber (HHF) as reinforcement such that they can be used for construction of embankments and land reclamation projects. The effect of fiber content on soil - fly ash mixture was observed through a series of laboratory tests such as compaction tests, CBR and unconfined compression tests. From the stress - strain curves, it was observed that the UCC strength for the optimised soil - flyash mixture reinforced with 0.75% human hair fibers is nearly 2.85 times higher than that of the untreated soil. Further, it has been noticed that there is about 7.73 times increase in CBR for the reinforced soil compared to untreated soil. This drastic increase in strength may be due to the fact that HHF offer more pull-out resistance which makes the fibers act like a bridge to prevent further cracking and thereby it improves the toughness which in turn prevent the brittle failure of soil-flyash specimen. Hence, the test results reveal that the inclusion of randomly distributed HHF in soil significantly improves the engineering properties of soil and can be effectively utilized in pavements. SEM analysis explained the change of microstructures and the formation of hydration products that offered increase in strength and it was found to be in accordance with strength tests.

• Journal of the Korean Society for Railway
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• v.14 no.4
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• pp.354-363
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• 2011

Existing railway bridges have been going through various improvements since the past, with new improvement plans being formed based on social and technological demands. However, there is the need, above all, for an efficient execution plan due to the great number of sites and excessive amount of required expenses contrary to limited assets. The system itself must be held in question in order to systemize various improvement plans, to define and describe factors while utilizing evaluation methods for significance and correlation to achieve generalization. This paper is focused on determining the priority of various improvement plans through the optimization selection process of mutually evaluating alternative plans under various evaluation standards, thus corresponding to the decision-making purpose. The AHP analysis technique was applied for systemization setting and preference evaluation, while the HPT procedure was applied to develop and select appropriate improvement plan factors.

• Korean Chemical Engineering Research
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• v.56 no.6
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• pp.811-818
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• 2018

A fire and explosion accident caused by a liquefied petroleum gas (LPG) welding and cutting torch gas leak occurred 10 m underground at the site of reinforcement work for bridge columns, killing four people and seriously injuring ten. We conducted a comprehensive investigation into the accident to identify the fundamental causes of the explosion by analyzing the structure of the construction site and the properties of propane, which was the main component of LPG welding and cutting work used at the site. The range between the lower and upper explosion limits of leaking LPG for welding and cutting work was examined using Le Chatelier's formula; the behavior of LPG concentration change, which included dispersion and concentration change, was analyzed using the fire dynamic simulator (FDS). We concluded that the primary cause of the accident was combustible LPG that leaked from a welding and cutting torch and formed a explosion range between the lower and upper limits. When the LPG contacted the flame of the welding and cutting torch, LPG explosion occurred. The LPG explosion power calculation was verified by the blast effect computation program developed by the Department of Defense Explosive Safety Board (DDESB). According to the fire simulation results, we concluded that the welding and cutting torch LPG leak caused the gas explosion. This study is useful for safety management to prevent accidents caused by LPG welding and cutting work at construction sites.

• Journal of the Korean Society of Earth Science Education
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• v.14 no.3
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• pp.292-301
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• 2021

This study is a basic research to apply ESD linked to SDGs to pre-service teachers majoring in earth science education. The purpose of this study is to evaluate carbon literacy by analyzing the awareness, attitude and knowledge, subjective norms, and behavioral control of the carbon footprint internalized by pre-service teachers. Pre-service teachers recognize the carbon footprint as their responsibility, but are not willing to pay the cost and accept inconveniences of the actions to reduce carbon footprint. They also support actions to reduce carbon footprint, but do not demand the actions from others. While they have sufficient knowledge about carbon mitigation actions, their conception of causes and effects of global warming is unstable. Pre-service teachers will go out to school sites and teach millions of students about global warming. It is essential to educate these teachers on the economic cost and social responsibility of reducing their carbon footprints. It is also important to find ways to bridge the gap between their thought and action. It is hoped that this study on pre-service teachers' carbon literacy will lead to realizing ESD.

• Journal of Yeungnam Medical Science
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• v.39 no.4
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• pp.322-331
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• 2022

Background: The combined use of biomaterials for regeneration may have great biological relevance. This study aimed to compare the regenerative potential of biphasic calcium phosphate (BCP) alone and with growth factor enamel matrix derivatives (EMDs) for the regeneration of intrabony defects at 1 year. Methods: This randomized controlled trial included 40 sites in 29 patients with stage II/III periodontitis and 2/3 wall intrabony defects that were treated with BCP alone (control group) or a combination of BCP and EMD (test group). BCP alloplastic bone grafts provide better bio-absorbability and accelerate bone formation. EMDs are commercially available amelogenins. Mean values and standard deviations were calculated for the following parameters: plaque index (PI), papillary bleeding index (PBI), vertical probing pocket depth (V-PPD), vertical clinical attachment level (V-CAL), and radiographic defect depth (RDD). Student paired and unpaired t-tests were used to compare the data from baseline to 12 months for each group and between the groups, respectively. The results were considered statistically significant at p<0.05. Results: At 12 months, the PI and PBI scores of the control and test groups were not significantly different (p>0.05). The mean V-PPD difference, V-CAL gain, and RDD difference were statistically significant in both groups at 12 months (p<0.001 for all parameters). Intergroup comparisons showed that the mean V-PPD reduction (2.13±1.35 mm), V-CAL gain (2.53±1.2 mm), and RDD fill (1.33±1.0 mm) were statistically significant between the groups at 12 months (p<0.001 for all parameters). Conclusion: BCP and EMDs combination is a promising modality for the regeneration of intrabony defects.