• Journal of Microbiology and Biotechnology
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• v.22 no.1
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• pp.92-99
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• 2012

The optimal physical factors affecting enzyme production in an airlift fermenter have not been studied so far. Therefore, the physical parameters such as aeration rate, pH, and temperature affecting PLA-degrading enzyme production by Actinomadura keratinilytica strain T16-1 in a 3 l airlift fermenter were investigated. The response surface methodology (RSM) was used to optimize PLA-degrading enzyme production by implementing the central composite design. The optimal conditions for higher production of PLA-degrading enzyme were aeration rate of 0.43 vvm, pH of 6.85, and temperature at $46^{\circ}C$. Under these conditions, the model predicted a PLA-degrading activity of 254 U/ml. Verification of the optimization showed that PLA-degrading enzyme production of 257 U/ml was observed after 3 days cultivation under the optimal conditions in a 3 l airlift fermenter. The production under the optimized condition in the airlift fermenter was higher than un-optimized condition by 1.7 folds and 12 folds with un-optimized medium or condition in shake flasks. This is the first report on the optimization of environmental conditions for improvement of PLA-degrading enzyme production in a 3 l airlift fermenter by using a statistical analysis method. Moreover, the crude PLA-degrading enzyme could be adsorbed to the substrate and degraded PLA powder to produce lactic acid as degradation products. Therefore, this incident indicates that PLA-degrading enzyme produced by Actinomadura keratinilytica NBRC 104111 strain T16-1 has a potential to degrade PLA to lactic acid as a monomer and can be used for the recycle of PLA polymer.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.37 no.5
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• pp.303-313
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• 2019

After a disaster happens in urban areas, many people need support for a quick evacuation. This work aims to develop a method for the calculation of the most feasible evacuation route inside buildings. In the methodology we simplify the geometry of the structural and non structural elements from the BIM (Building Information Modeling) to store them in a spatial database which follows standards to support vector data. Then, we apply the multicriteria analysis with the allocation of prioritization values and weight factors validated through the AHP (Analytic Hierarchy Process), in order to obtain the Importance Index S(n) of the elements. The criteria consider security conditions and distribution of the building's facilities. The S(n) is included as additional heuristic data for the calculation of the evacuation route through an algorithm developed as a variant of the $A^*$ pathfinding, The experimental results in the simulation of evacuation scenarios for vulnerable people in healthy physical conditions and for the elderly group, shown that the conditions about the wide of routes, restricted areas, vulnerable elements, floor roughness and location of facilities in the building applied in the multicriteria analysis has a high influence on the processing of the developed variant of $A^*$ algorithm. The criteria modify the evacuation route, because they considers as the most feasible route, the safest instead of the shortest, for the simulation of evacuation scenarios for people in healthy physical conditions. Likewise, they consider the route with the location of facilities for the movement of the elderly like the most feasible in the simulation of evacuation route for the transit of the elderly group. These results are important for the assessment of the decision makers to select between the shortest or safest route like the feasible for search and rescue activities.

• Journal of Mechanical Science and Technology
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• v.15 no.5
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• pp.671-680
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• 2001

Boundary condition is one of the major factors to influence the numerical stability and solution accuracy in numerical analysis. One of the most important physical boundary conditions in the flowfield analysis is the wall boundary condition imposed on the body surface. To solve a two-dimensional Euler equation, totally four numerical wall boundary conditions should be prescribed. Two of them are supplied by the flow tangency condition. The other two conditions, therefore, should be prepared additionally in a suitable way. In this paper, four different sets of wall boundary conditions are proposed and then applied to solve high-speed flowfields around a quarter circle geometry. A two-dimensional compressible Euler solver is prepared based on the finite volume method. This solver hires three different upwind schemes; Steger-Warmings flux vector splitting, Roes flux difference splitting, and Lious advection upstream splitting method. It is found that the way to specify the additional numerical wall boundary conditions strongly affects the overall stability and accuracy of the upwind schemes in high-speed flow calculation. The optimal wall boundary conditions should be also chosen very carefully depending on the numerical schemes used to solve the problem.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.32 no.3
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• pp.65-74
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• 2000

This study was carried out to acquire basic data necessary for the use of rice-straw chemical pulp. It investigated the proper bleaching conditions when rice-straw chemical pulps(alkaline sulfite-Na2S2O4 pulp) were bleached with the various kinds of bleaching agents. And physical properties of bleached pulps were tested. The results of this study were as follows; 1, The proper conditions of chlorine sequence were determined to be 4% concentration of chlorine 25$^{\circ}C$ of reaction temperature and 50 minutes of reaction time. 2. For calcium hypochlorite sequence the proper conditions of chemical concentration reac-tion temperature and reaction time were 3% 25$^{\circ}C$ and 20 minutes respectively. 3. For chlorine dioxide sequence the proper conditions were 1% concentration of chlorine dioxide 70$^{\circ}C$ of reaction temperature and 2hr. of reaction time. 4. The proper conditions of hydrogen peroxide sequence were 1.5% concentration of hydro-gen peroxide 70$^{\circ}C$ of reaction temperature and 1hr. of reaction time respectively. 5. When the rice-straw chemical pulp were bleached with four kinds of bleaching agents methioned above in the proper conditions respectively brightnesses were the order of chlorine dioxide calcium hypochlorite, chlorine, hydrogen peroxide. And strengthes of pulps bleached with chlorine dioxide and hydrogen peroxide were higher than those of pulps bleached with other bleaching agents.

• Safety and Health at Work
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• v.2 no.4
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• pp.313-320
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• 2011

Objectives: To analyze the association between changes in perceived physical and psychosocial working conditions and change of sickness absence days in younger and older (< 50 and ${\geq}50$ years) food industry employees. Methods: This was a follow up study of 679 employees, who completed working conditions survey questionnaires in 2005 and 2009 and for whom the requisite sickness absence data were available for the years 2004 and 2008. Results: Sickness absence increased and working conditions improved during follow-up. However, the change of increased sickness absence days were associated with the change of increased poor working postures and the change of deteriorated team spirit and reactivity (especially among < 50 years). No other changes in working conditions were associated with the changes in sickness absence. Conclusion: Sickness absence is affected by many factors other than working conditions. Nevertheless, according to this study improving team spirit and reactivity and preventing poor working postures are important in decreasing sickness absence.

• Proceedings of the Korean Fiber Society Conference
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• 1989.06a
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• pp.50-51
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• 1989

• Proceedings of the Korean Vacuum Society Conference
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• 2001.02a
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• pp.76-77
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• 2001

• Journal of Korean Medical Ki-Gong Academy
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• v.7 no.2
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• pp.111-133
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• 2004

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2009.03a
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• pp.106-107
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• 2009

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2009.03a
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• pp.108-109
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• 2009