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선형계획법에 의한 PC Box Girder 교양단면의 (橋梁斷面) 최적설계에 관한 연구
신재철(Jea Chul Shin) 대한공업교육학회 1982 대한공업교육학회지 Vol.7 No.2
This study is intended to develop an efficient formulation and a practical computer program for the optimal section design of post-tensioned box girder bridges, which are known as one of the most efficient structural systems, usually used for the mid-long span bridge type. Simple span box girder bridges taken from a conventional design manual are adopted as design examples. It may be stated that the optimization technique proposed in this study gives more efficient and economical results than the conventional design. Furthermore, it may be stated that the computor program developed in this study could be directly used for the practical design of a post tensioned box girder bridge even by the new designers.
김형민(Hyung Min Kim),성용주(Yong Joo Sung),박영석(Young Seok Park),신재철(Jea Chul Shin),서용교(Yong Kyo Seo) 한국펄프·종이공학회 2016 펄프.종이技術 Vol.48 No.6
The effects of heat treatment conditions on the properties of rice husk were evaluated in this study. The commercial products of the heat treated rice husk were also investigated in terms of the changes in the properties by the manufacturing methods such as the indirect rotary kiln method and the direct combustion method. The indirect rotary kiln treatment for the commercial product resulted in the lower carbonization and the lower absorption of methylene blue of the heat treated rice husk product than those of the direct heat treated rice husk product. In addition, the effect heat treatment was analyzed under two different conditions - by using muffle furnace at air atmosphere condition and by using tube furnace at nitrogen atmosphere condition - for comparative analysis. The rice husk treated in nitrogen condition showed less carbonation, less changes in pH and no significant changes in methylene blue absorption properties, compared to the rice husk treated in the air condition. The pH of the rice husk treated in the air condition changed from 3.5 at 300°C treatment to 9.5 at 500°C treatment. Also, the absorption capacity of the rice husk treated in the air condition was greatly improved as the treatment temperature increased.
김형민(Hyung Min Kim),성용주(Yong Joo Sung),박영석(Young Seok Park),신재철(Jea Chul Shin) 한국펄프·종이공학회 2016 펄프.종이기술 Vol.48 No.3
The applicability of rice husk fiber as a raw material for eco-friendly pulp mold was evaluated in this study. The higher demand of environmental friendly packaging material resulted in the more interest for the natural fiber based pulp mold. The rice husk which is an abundant agricultural byproduct in Asia could be defiberized by an alkaline digestion process. The changes in the pulp mold making process and the properties of pulp mold by the addition of the rice husk were investigated. The addition of rice husk fiber to the pulp mold made with OCC or UBKP resulted in the increase in drainage at the pulp mold forming process. In case of UBKP pulp mold, the addition of rice husk fiber increased the drying efficiency after pulp mold forming since the structure of pulp mold became more bulkier by the addition of the rice husk fiber. Those results showed the rice husk fiber could be applied to the pulp mold manufacturing as one of the eco-friendly natural fiber resources.
김형민(Hyung Min Kim ),성용주(Yong Joo Sung),박영석(Young Seok Park),신재철(Jea Chul Shin) 한국펄프·종이공학회 2016 펄프.종이기술 Vol.48 No.5
The changes in the properties of the rice husk fibers by the mechanical treatment were evaluated in order to increase the usability of the rice husk fiber as an alternative wood fiber. The additional mechanical treatment of the flake fraction after the rice husk digestion resulted in the increase of the rice husk fiber portion. The fibers obtained by the additional treatments of the flake fraction showed no significant difference between the rice husk fibers directly originated from the rice husk digestion. The mechanical treatment of the rice husk fibers with PFI mill showed the bigger decrease in the freeness than those of softwood unbleached fibers treated with same method. The larger changes in the shape such as fiber length, fiber width and fine contents were found in the rice husk fiber than those in the softwood unbleached fibers. Especially, the lower level of mechanical treatment such as 5,000 revolution of PFI mill resulted in the significant changes of rice husk fiber properties unlike softwood fibers. Those results showed the rice husk fibers were more susceptible to the mechanical treatment such as refining process.
김동성(Dong Sung Kim),성용주(Yong Joo Sung),박영석(Young Seok Park),신재철(Jea Chul Shin),서용교(Yong Kyo Seo) 한국펄프·종이공학회 2016 펄프.종이技術 Vol.48 No.6
The rice husk would be one of most abundant agricultural residue. Although the high ash contents of rice husk which has been a major obstacle to utilize the rice husk could be extracted, the fibers of rice husk after the extraction process showed the lower mechanical properties as papermaking fibers. This study was conducted in order to increase the usability of rice husk as an alternative source to wood fiber by upgrading the properties of the rice husk fiber. The rice husk fiber after the ash extraction was treated with the mild oxidation treatment by using the ozone and the hydrogen peroxide. The fiber properties such as the brightness and the zeta potential were evaluated depending on the treatment conditions. The properties of handsheets made with rice husk were also evaluated. The oxidation treatment of the rich husk fiber increased the brightness and the zeta potential. The paper made from the treated rice husk fiber showed the lower contact angle and the higher tensile strength. The applicability of rice husk as the papermaking fiber could be improved by the oxidation treatment.