• Journal of Energy Engineering
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• v.28 no.4
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• pp.8-12
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• 2019

Thermal amine scrubbing is the most advanced CO₂ capture technique but its largescale application is hindered due to the large heat requirement during solvent regeneration step. The addition of a solid metal oxide catalysts can optimize the CO₂ desorption rate and thus minimize the energy consumption. Herein, we evaluate the solvent regeneration performance of Monoethanolamine (MEA) and Diethanolamine (DEA) solvents without and with two metal oxide catalysts (TiO₂ and V₂O₅) within a temperature range of 40-86℃. The solvent regeneration performance was evaluated in terms of CO₂ desorption rate and overall amount of CO₂ desorbed during the experiments. Both catalysts improved the solvent regeneration performance by desorbing greater amounts of CO₂ with higher CO₂ desorption rates at low temperature. Improvements of 86% and 50% in the CO₂ desorption rate were made by the catalysts for MEA and DEA solvents, respectively. The total amount of the desorbed CO₂ also improved by 17% and 13% from MEA and DEA solvents, respectively. The metal oxide catalyst-aided regeneration of amine solutions can be a new approach to minimize the heat requirement during solvent regeneration and thus can remove a primary shortfall of this technology.

• Land and Housing Review
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• v.10 no.1
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• pp.1-7
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• 2019

This article assumes that the first newtown has declined in Korea. Urban regeneration projects should be implemented for regeneration for CBD in Newtown as well as small local cities. The purpose of this article is to analyze the character of the subway area and to suggest the key issues for regeneartion in the subway area. Especially focussing on the local important commercial function in 5 subway areas. As a result of analyzing 5 subway areas according to basic statistical data, field interviews, and legal decline diagnostic index, all five commercial districts showed decline. In particular, the decline of Baekseok Station area appears to be serious, and there is a key factor that attracts the decline of the commercial area such as the long - term building or the closure rate of each commercial area. In addition, the vacancy rate is increasing due to large distribution facilities in new cities, the entry of new floating facilities on the outskirts, and unsold new stores, and the recession is accelerating. In this way, the signs of decline in the core of the new city are enriched, but the current Urban Regeneration Act is a legal system with a policy goal of regeneration of small and medium cities in the provinces as a system to promote the function of core bases rather than the overall redevelopment of new cities. Therefore, preemptive response is needed for the regeneration in those areas.

• The Journal of the Korean dental association
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• v.47 no.11
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• pp.758-768
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• 2009

Purpose : Schulte introduced immediate implant cases in 1970s, since then many patients have been treated by immediate implants. The aim of this study was to evaluate the cumulative survival rate of immediate implant and to analyze various factors associated with survival of immediate implant in a 8-year period retrospectively. Materials and methods : From May, 2000 to October, 2007, 77 implants were placed in 63 patients immediately after tooth extraction at Department of Periodontology, Yonsei University Hospital. The implant survival rate was analyzed using a life-table analysis. After delivery of prosthesis, along 1 year of observation period, all implants were evaluated clinically and radiographically. Results : Among 77 implants, 59 were placed in maxilla and 18 in mandible. The most common site of the implantation was Mx anterior (65%). The overall survival rate was 94.8% over a mean follow-up period of $44.2{\pm}21$ months and the 8-year cumulative survival rate was 94.6%. Failure occurred in 4 implants, all of which were due to early failures. None of the following factors were significantly associated with the survival of immediate implants: advanced surgical technique including bone graft and guided bone regeneration, the types of implants, causes of tooth loss, and types of prosthesis. Conclusion : On the basis of 8-year life time analysis, immediate implant placement can be considered a safe and predictable treatment mordality.

• Journal of Periodontal and Implant Science
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• v.41 no.2
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• pp.86-91
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• 2011

Purpose: The aim of this study was to analyze the short-term predictability and reliability of Astra Tech implants according to the demographical distribution of patients and condition of implant sites and location of implants. Methods: Among patients treated with Astra Tech implant (Astra Tech AB) in the Department of Periodontology at the Dental Hospital of Yonsei University of College of Dentisry and K Dental Clinic from May 2004 to March 2009, 195 implants in 98 patients which had been restored more than 6 months ago were reviewed in this study. Following data were reviewed from patient charts and implants success rate was examined: 1) patient type and implant location, 2) bone status at the implant site, 3) diameter and length of the placed implants, 4) presence or absence of bone augmentation and types of the augmentation. Results: The results from this study are as follows: 1) most implants were placed in the molar area, especially 1st molar area of maxilla, 2) most implants were placed at $D_2$ and $D_3$ bone type, 3) most implants were placed in areas of B and C bone quantity, 4) autogenous and alloplastic bone graft and artificial membrane were used for placement of 74 implants. Conclusions: Short-term survival rate of Astra Tech implants was 100%.

• 대한치주과학회:학술대회논문집
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• 2006.11a
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• pp.150-150
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• 2006

• 대한치주과학회:학술대회논문집
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• 2006.11a
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• pp.149-149
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• 2006

• Journal of Periodontal and Implant Science
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• v.39 no.4
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• pp.413-423
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• 2009

Purpose: The presented study aims to evaluate the effects of osteoporosis on dental implants by analyzing a 12-year cumulative survival rate of implants placed in patients with osteoporosis. Methods: 37 patients with history of osteoporosis were selected from a pool of dental implant patients treated at the Department of Periodontology in Yonsei University Hospital between 1993 and 2007. The cumulative survival rate is quantified using data collected from 164 placed implants in the selected 37 patients. Results: 3 out of the 164 implants failed and the cumulative survival rate was observed at 95.1%. The survival rates of the implants according to patients' age were 97.41% (<60) and 100% ($60\leq$). The lower survival rate was directly proportional to younger age, and this relationship is statistically significant (P<0.05). The survival rates of implants according to diagnostic criteria were 95.45% (osteopenia) and 98.59% (osteoporosis; 2 out of 142 implants placed in osteoporosis patients failed). The difference in the two survival rates is statistically significant (P<0.05). The survival rates according to the region of implants do not have statistically significant difference. The survival rates according to the different length and diameter of the implants do not have statistically significant difference. The survival rates of implants accompanied and not accompanied by bone augmentation were 92.11% and 100%, respectively. The difference in the two survival rates is statistically significant (P<0.05). The survival rates of implants placed in patients with and without history of medication for osteoporosis treatment are 96.67% and 99.04%, respectively. The difference in the two survival rates is statistically significant (P<0.05). Conclusions: A high cumulative survival rate of dental implants, similar to one found in non-osteoporosis patients, is observed in osteoporosis patients, indicating the possibility that placing dental implants on patients with osteoporosis can be considered with high treatment predictability.

• Journal of Periodontal and Implant Science
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• v.39 no.3
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• pp.293-301
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• 2009

Purpose: The purpose of this study is to show the total survival rate of implants with maxillary sinus floor elevation and the effects that reach the survival rate by classifying types of graft materials, implant surface, operation method, bone height. Methods: In a total of 131 patients, 251 implants with sinus floor elevation were installed simultaneously or after regular healing. Various bone grafts (autograft, xonograft, allograft, alloplast) and implant surface (MTX-HA implant, chemical etching implant, Titanium oxide surface implant, resorbable blasting media implant, resorbable blast texturing implant, HA-coated implant) were used. All implants were investigated clinically and radiographically, being with 1 to 5 years follow-up period after installation. Results: The survival rate of 251 implants with maxillary sinus floor elevation was 94%. The types of implant, surface, graft material, bone height have no statistically signi-ficant differencies. Conclusions: It can be suggested that maxillary sinus floor elevation may have predictable result with various bone graft materials and implant surface.

• Journal of Plant Biology
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• v.33 no.4
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• pp.243-251
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• 1990

Polyamine titers and the activities of arginine decarboxylase(ADC) and ornithine decarboxylase (ODC), enzymes which catalyze rate-limiting steps in polyamine biosynthesis, were investigated during polar regeneration of Populus leaf segments. The polar regeneration occurred at the basal cut end of Populus leaf segments through cell division around the vascular bundle. In the process of polar regeneration, the titers of putrescine and spermidine increased rapidly but the content of spermine remained constant. The leaf segments were then divided into three separte part ; the proximal, middle and distal. Spermidine titers showed an increase mainly in the proximal parts where polar regeneration occurred. On the other hand, putrescine titers showed an increase in the other two parts. In the course of polar regeneration, the activities of ADC and ODC increased, the ADC activities being higher than those of ODC. However, ODC activity was higher in the proximal part. Therefore, the spermidine contents and ODC activities are suggested to be related to polar regeneration in Populus leaf segments.

• 대한치주과학회:학술대회논문집
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• 2006.11a
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• pp.126-127
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• 2006