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김태형(Tae Hyung Kim),권오봉(Oh Boong Kwon),박정(Jeong Park),길상인(Sang-In Keel),윤진한(Jin-Han Yun),박종호(Jong Ho Park) 한국연소학회 2015 한국연소학회지 Vol.20 No.4
Oxy-methane nonpremixed flames diluted with CO₂ were investigated to clarify impact of radiation heat loss and chemical effects of additional CO₂ to oxidizer stream on flame extinction. Flame stability maps were presented with functional dependencies of critical diluents mole fraction upon global strain rate at several oxidizer stream temperatures in CH₄-O₂/N₂, CH₄-O₂/CO₂, and CH₄-O₂/CO₂/N₂ counterflow flames. The effects of radiation heat loss on the critical diluent mole fractions for flame extinction are not significant even at low strain rate in nonpremixed CH₄-O₂/N₂ diffusion flame, whereas those are significant at low strain rate and are negligible at high strain rate (> 200 s<SUP>-1</SUP>) in CH₄-O₂/CO₂ and CH₄-O₂/CO₂/N₂ counterflow flames. Chemical effects of additional CO₂ to oxidizer stream on the flame extinction curves were appreciable in both CH₄-O₂/CO₂ and CH₄-O₂/CO₂/N₂ flames. A scaling analysis based on asymptotic solution of stretched flame extinction was applied. A specific radical index, which could reflect the OH population in main reaction zone via controlling the mixture composition in the oxidizer stream, was identified to quantify the chemical kinetic contribution to flame extinction. A good correlation of predicted extinction limits to those calculated numerically were obtained via the ratio between radical indices and oxidizer Lewis numbers for the target and baseline flames. This offered an effective approach to estimate extinction strain rate of nonpremixed oxy-methane flames permitting air infiltration when the baseline flame was taken to nonpremixed CH₄-O₂/N₂ flame.
MgCl₂ 溶液中에서 SUS 304 鋼 鎔接部의 SCC억제에 관한 연구
임우조,권오봉 釜山水産大學校 1986 釜山水産大學 硏究報告 Vol.26 No.1-2
SUS 304 鋼 鎔接部에 대해 여러가지 濃度의 비등 염화 마그네슘 溶液中에서 SCC 억제를 위한 방법으로서 電氣防蝕法을 실시하여, 一定負荷에서 濃度 條件에 따른 限界 防融電流密度를 究明하였다. 중요한 結果를 要約하면 다음과 같다. 1) SCC 억제를 위한 限界 防融電流密度 以下로 防蝕할 때 용접열 영향부의 龜裂初期 潛伏時間은 모재보다 용접열 사이클로 인한 銳敏化 및 軟化 현상에 의해 빨라진다. 2) 일정한 防蝕電流密度下에서 용접열 영향부의 SCC 억제는 MgCl溶液의 限界濃度에 의해 제어될 수 있다. 3) 용접열 영향부의 限界防融電流密度는 MgCl₂溶液의 濃度에 비례해서 증가한다. The anti-stress corrosion cracking method by current density of cathodic protection was studied for stress corrosion cracking of SUS 304 stainless steel weldments in the environment of various MgCl₂boiling solution(wt%). Main results obtained are as follows: 1) Under the conditions below the critical current density of cathodic protection for anti-stress corrosion cracking, the latent time of crack initiation of weld heat affected zone occurs more rapidly than that of base metal because of the phenomenon of sensitizing and softening caused by weld heat cycles. 2) Under the constant current density of cathodic protection, the anti-stress corrosion cracking of weld heat affected zone can be controlled by critical concentration of MgCl₂solution. 3) The critical current density of cathodic protection of weld heat affected zone increases in proportion to concentration of MgCl₂solution.