한국산학연협회 서동석 회장 인터뷰

서동석 한국공학교육학회 2015 Ingenium(人材니움) Vol.22 No.1

인터뷰 : 한국산학연협회 서동석 회장 인터뷰

서동석 한국공학교육학회(구 한국공학교육기술학회) 2015 공학교육동향 Vol.22 No.1

Sintering and Dissolution of Bone Ash-Derived Hydroxyapatit

서동석,김영국,이종국 대한금속·재료학회 2010 METALS AND MATERIALS International Vol.16 No.4

Bone ash-derived hydroxyapatite (HA) ceramics were prepared by pressureless sintering and hot pressing,and their dissolution behavior was examined in buffered water. HA powder was obtained by soaking bone ash in a 0.1M NaOH solution at 80 °C, followed by calcination at 1000 °C to completely remove the organic material. The crystal structure of the HA powder with a particle size of approximately 1 μm was mainly hydroxyapatite with a minimal amount of α-tricalcium phosphate. To improve densification, the powder was hot-pressed at 1000 °C for 0.5 h under a pressure of 30 MPa in an Ar atmosphere. The sintered density of the hot-pressed HA was 95 % of the theoretical density, which is much higher than the 70% obtained for the pressureless-sintered compact. In the porous HA ceramics obtained by pressureless sintering, dissolution occurred adjacent to the pores rather than in the dense part, which increased the residual porosity. On the other hand, the hot-pressed HA showed grain boundary dissolution followed by particle loosening.

Preparation of Hydroxyapatite Powder Derived from Tuna Bone and Its Sintering Property

서동석,김용국,황규홍,이종국 한국세라믹학회 2008 한국세라믹학회지 Vol.45 No.10

Hydroxyapatite (HA) was prepared from waste tuna bone, and its sintering property and dissolution behavior were investigated. Tuna bone derived-HA powder consisted of mainly HA and small amount of MgO. Porous HA ceramics with sintered density of 79% was obtained by pressureless sintering at 1200oC. Meanwhile, HA ceramics prepared by hot pressing at 1000oC showed dense microstructure with sintered density of 95%. Immersion test revealed that both porous and dense HA ceramics were stable in liquid environment without distinct evidence of surface dissolution. It may be assumed that the presence of Mg in tuna bone-derived HA may improve dissolution resistance of HA. Hydroxyapatite (HA) was prepared from waste tuna bone, and its sintering property and dissolution behavior were investigated. Tuna bone derived-HA powder consisted of mainly HA and small amount of MgO. Porous HA ceramics with sintered density of 79% was obtained by pressureless sintering at 1200oC. Meanwhile, HA ceramics prepared by hot pressing at 1000oC showed dense microstructure with sintered density of 95%. Immersion test revealed that both porous and dense HA ceramics were stable in liquid environment without distinct evidence of surface dissolution. It may be assumed that the presence of Mg in tuna bone-derived HA may improve dissolution resistance of HA.

우리나라 工産品의 比較優位 패턴 分析

徐東錫 연세대학교 경영연구소 1981 연세경영연구 Vol.18 No.2

Townscape Characteristics of Traditional Conservative Residential Area, Oxford

서동석,최승희 한국전통조경학회 2010 한국전통조경학회지 Vol.8 No.-

In this study, Oxford in the UK which Heritage Conservation District's landscape management in the residential area is relatively well were identified as examples of the target as development, conservation and landscape planning characteristic trends. This conservation status of the different residential areas, and landscape components were analyzed. Characteristics through this are evaluated in future studies considering the development of conservation and landscape planning of residential areas will be used as the basis for guidelines such as Germany and residential district of domestic cultural preservation officer for the necessity of managing limited. Oxford in the UK is distributed in the residential area to obtain basic information about the residential conservation area are as follows: Walton Manor, Wolvercote with Godstow, St Clements and Iffley Road, Old Headington, Headington Quarry, Marston Village, Headington Hill, Osney Town and Bisney (1st case). Secured prior literature survey and drawing, photography and colorimeter using slides, visit the environment through research and interviews with design and architectural planning and status were determined from the side. The purpose of this study is to introduce example analysis of townscape that the quality of a place and its individuality depend very much upon the relationship between them, and of individual objects, trees, lamp-posts and so on. There are many places in Oxford which are of a high quality with house types, public facility, road system, site, streetscape, unity of diversity and social space, etc. These are grand examples of townscape, but the conservative residential areas in the whole of the Oxford city should benefit from careful design of the environment. New development or changes to existing buildings should be carried out in a way which acknowledges its surroundings and is a good neighbour, both in the physical and social sense. In all new developments the scale of new buildings and the materials and colors used should respect the character of their surroundings and have due regard to the setting of any listed building. Outline applications where the treat- ment of spaces between and around buildings is of importance should also include townscape of visual assessment proposals to complement details of siting and layout. The height of any new building will be considered in relation to policies and with regard to the existing townscape design and longer views, and to the effect on existing and proposed neighbours.

Dissolution-Resistance of Glass-Added Hydroxyapatite Composites

서동석,이종국 대한금속·재료학회 2009 METALS AND MATERIALS International Vol.15 No.2

Hydroxyapatite (HA) has generated a great deal of interest as a promising implant material. However, its poor mechanical properties induced by severe dissolution in biological milieu limit medical applications and lead to clinical failure. In this study, HA ceramics with 30P2O5-30CaO-40Na2O glass (1.0 wt.% and 2.5 wt.%) were prepared to improve the resistance of monophase HA. The monophase HA sintered body showed microstructural degradation due to grain boundary dissolution in buffered water. However, the dissolution-resistance of HA/glass composites was significantly improved and showed no apparent evidence of dissolution. This suggests that a less soluble glass phase should be placed at grain boundaries to protect HA from dissolution. Hydroxyapatite (HA) has generated a great deal of interest as a promising implant material. However, its poor mechanical properties induced by severe dissolution in biological milieu limit medical applications and lead to clinical failure. In this study, HA ceramics with 30P2O5-30CaO-40Na2O glass (1.0 wt.% and 2.5 wt.%) were prepared to improve the resistance of monophase HA. The monophase HA sintered body showed microstructural degradation due to grain boundary dissolution in buffered water. However, the dissolution-resistance of HA/glass composites was significantly improved and showed no apparent evidence of dissolution. This suggests that a less soluble glass phase should be placed at grain boundaries to protect HA from dissolution.

Electrically Aligned-Al₂O₃ Flakes Reinforced Polymer Composites for High Thermal Conductivity

서동석,유명재,이우성,임호선,김성환,박성대 한국고분자학회 2011 한국고분자학회 학술대회 연구논문 초록집 Vol.2011 No.2

Acute Oral or Dermal and Repeated Dose 90-Day Oral Toxicity of Tetrasodium Pyrophosphate in Spraque Dawley (SD) Rats

서동석,권민,성하정,박철범 환경독성보건학회 2011 환경독성보건학회지 Vol.26 No.-

Objectives: Tetrasodium pyrophosphate (TSP) is used in processed meat products, as an emulsifier in cheese, and as a color preservative in soybean paste. However, little is known about its toxicity. This study was conducted to investigate the potential acute and repeated dose toxicity of TSP in Spraque Dawley (SD) rats. Methods: In the acute study, animals were administered with oral or dermal doses of 2,000 mg/kg TSP. In the repeated dose study, animals were administered doses of 0, 250, 500, and 1,000 mg/kg by oral gavage five times a week for 90 days. Results: In acute toxicity studies, no dead animals or abnormal necropsy findings were found in the control or treated group. In the repeated dose toxicity study, there were no significant changes in body weight in the 1,000 mg/kg treatment group, or food consumption, urinalysis,and hematology in any group. With regards serum biochemistry, the levels of total protein, albumin, A/G ratio, triglyceride, calcium and inorganic phosphate were altered at doses of 500 and 1,000 mg/kg. However, no changes were observed at the dose of 250 mg/kg. With regards histopathological findings, cortical tubular basophilia of the kidney increased at the dose of 1,000 mg/kg, but not at doses of 250 and 500 mg/kg. No significant changes were observed in other organs at doses of 250, 500, and 1,000 mg/kg. Conclusions: Based on the results, TSP is unclassified according to the Globally Harmonization System, with an LD50 value of over 2,000mg/kg. The no observed effect level (NOEL) and no observed adverse effect level (NOAEL) were 250 and 500 mg/kg /day respectively and the target organ appears to be the kidney.

外國의 宗合商社

徐東錫 韓國外國語大學校 1984 世友 Vol.6 No.1