• Journal of the Korean Institute of Gas
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• v.2 no.3
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• pp.12-17
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• 1998

Fault tree construction for hazard assessment requires so much time and labor, so it is very difficult to be applied to the large scale chemical plant. For the synthesis of fault tree in chemical processes, this study represents the cause-effect relations between process variables by using the Signed Directed Graph(SDG), and has synthesized Fault Tree(FT) by searching the causes of fault events using the general operator and loop operators defined corresponding to path characteristics on the SDG.

• Landscaping Tree
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• s.130
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• pp.34-40
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• 2012

• Landscaping Tree
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• s.131
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• pp.29-37
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• 2012

• Journal of Ocean Engineering and Technology
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• v.27 no.2
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• pp.47-52
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• 2013

A subsea chemical injection system treats blockage problems in a subsea production system. It is important to treat problems quickly, because production delays cause fatal profit losses in a subsea production system. Therefore, the subsea industry requires a relatively higher reliability level for a production system compared to other industries. In this study, a subsea chemical injection system (linked to a control system) to inject chemicals into a subsea X-mas tree was analyzed. By using FSA (Formal Safety Assessment), the risk factors were defined and a quantitative risk analysis utilizing FTA (Fault Tree Analysis) and ETA (Event Tree Analysis) was performed. As a result, the effectiveness of a risk reduction option was evaluated.

• Carbon letters
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• v.9 no.3
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• pp.203-209
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• 2008

The objective of this work is to study the feasibility of the preparation of the activated carbon (AC) from coconut tree flowers using high temperature fluidized bed reactor (HTFBR). The activating agent used in this work is steam. The reactor was operated at various activation temperature (650, 700, 750, 800 and $850^{\circ}C$) and activation time (30, 60, 120 and 240 min) for the production of AC from coconut tree flowers. Effect of activation time and activation temperature on the quality of the AC preparation was observed. Prepared AC was characterized in-terms of iodine number, methylene blue number, methyl violet number, ethylene glycol mono ethyl ether (EGME) surface area and SEM photographs. The best quality of AC from coconut tree flowers (CFC) was obtained at an activation temperature and time of $850^{\circ}C$ and 1 hr restectively. The effectiveness of carbon prepared from coconut tree flowers in adsorbing crystal violet from aqueous solution has been studied as a function of agitation time, carbon dosage, and pH. The adsorption of crystal violet onto AC followed second order kinetic model. Adsorption data were modeled using both Langmuir and Freundlich classical adsorption isotherms. The adsorption capacity $q_m$ was 277.78 mg/g., equilibrium time was found to be 180 min. This adsorbent from coconut tree flowers was found to be effective for the removal of CV dye.

• Journal of the Korean Society of Safety
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• v.18 no.2
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• pp.64-72
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• 2003

A new reliability assessment methodology is presented and the new method is compared with fault tree analysis. The system is modeled by directed graph at a new methodology, which is composed of nodes and arcs. The directed graph corresponds to the layout of chemical process and is easy to construct. Therefore, the directed graph analysis is applicable to the chemical process that has complex sequence. The example of fault tree analysis and directed graph analysis is given. The directed graph analysis has proved to be a valuable and useful method for the reliability assessment of chemical process.

• Korean Chemical Engineering Research
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• v.56 no.2
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• pp.240-244
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• 2018

There is growing concern about cross infection among the patients to patients, patients to staffs, and tools to patients in healthcare facilities, especially in dentistry. In this study, the most widely used dental impression materials were prepared and the synergy effect of Chlorhexidine and essential oil on antimicrobial activity was examined in the impression materials. Chlorhexidine concentration of 0.1 wt% and 0.5 wt% showed no antimicrobial activity on Escherichia coli (E. coli) and Candida albicans. At 1.0 wt% Chlorhexidine, 0% of E. coli and 34.7% of Candida albicans were survived. Bergamot (Essential oil) concentration of 0.5 wt% and 1.0 wt% showed no antimicrobial activity on E. coli. At 2.0 wt% Bergamot oil, 71.9% of E. coli were survived. Tea tree oil (Essential oil) of 0.5 wt% showed no antimicrobial activity on E. coli. At 1.0 wt% Tea tree oil, 11.2% of E. coli was survived. At 2.0 wt% Tea tree oil, no E. coli was survived. However, no E. coli was survived at the concentration of 0.8 wt% Bergamot with 0.3 wt% Chlorhexidine. At the concentration of 0.8 wt% Tea Tree oil with 0.3 wt% Chlorhexidine, 1.3% of E. coli were survived. The experimental results showed that the synergy effects between Chlorhexidine and essential oils on antimicrobial activity were prominent.

• Journal of the Korean Institute of Gas
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• v.1 no.1
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• pp.81-86
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• 1997

This study is to estimate the possibility of accident in chemical plants from the analysis of system component which affects the occurrence of top event. Among the various risk assessment techniques, the Fault Tree Analysis which approaches deductively on the route of accident development was used in this study. By gate-by-gate method and minimal cut set, the qualitative and quantitative risk assessment for hazards in plants was performed. The probability of occurrence and frequency of top event was calculated from failure or reliability data of system components at stage of the quantitative risk assessment. In conclusion, the probability of accident was estimated according to logic pattern based on the Fault Tree Analysis. And the failure path which mostly influences on the occurrence of top event was found from Importance Analysis.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.34 no.11
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• pp.436-439
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• 1985

An effect of the salt solution on the Water Tree Propagation was shown systematically from the actions of the salt concentration in deionized water. It may be able to suggest that the tree propagation is possibly to be connected with an intervention of the electrochemical or chemical actions of the salt solution on water tree propagation, which may likely depend on the growth level of the trees. We have pointed out that it is necessary to study the structure of water tree under the electrical stress.

• Journal of Microbiology and Biotechnology
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• v.19 no.11
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• pp.1342-1347
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• 2009

We have isolated endophytic fungi from the Indian yew tree, Taxus baccata, and then screened for taxol production. Out of the 40 fungal cultures screened, one fungus Gliocladium sp. was found to produce taxol and 10-DABIII (10-deacetyl baccatin III). These compounds were purified by TLC and HPLC and characterized using UV-spectroscopy, ESI-MS, MS/MS, and proton NMR. One liter of Gliocladium sp. culture yielded $10\;{\mu}g$ of taxol and $65\;{\mu}g$ of 10-DABIII. The purified taxol from the fungus showed cytotoxicity towards cancer lines HL-60 (leukemia), A431 (epidermal carcinoma), and MCF-7 (breast cancer).