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다환방향족 탄화수소(PAHs) 오염토양의 과황산 산화 시 철 활성화제의 영향
최지연,박정도,신원식,Choi, Jiyeon,Park, Jungdo,Shin, Won Sik 한국지하수토양환경학회 2020 지하수토양환경 Vol.25 No.1
PAHs commonly found in industrial sites such as manufactured gas plants (MGP) are potentially toxic, mutagenic and carcinogenic, and thus require immediate remediation. In-situ chemical oxidation (ISCO) is known as a highly efficient technology for soil and groundwater remediation. Among the several types of oxidants utilized in ISCO, persulfate has gained significant attention in recent years. Peroxydisulfate ion (S<sub>2</sub>O<sub>8</sub><sup>2-</sup>) is a strong oxidant with very high redox potential (E<sup>0</sup> = 2.01 V). When mixed with Fe<sup>2+</sup>, it is capable of forming the sulfate radical (SO<sub>4</sub><sup>-·</sup>) that has an even higher redox potential (E<sup>0</sup> = 2.6 V). In this study, the influence of various iron activators on the persulfate oxidation of PAHs in contaminated soils was investigated. Several iron sources such as ferrous sulfate (FeSO<sub>4</sub>), ferrous sulfide (FeS) and zero-valent iron (Fe(0)) were tested as a persulfate activator. Acenaphthene (ANE), dibenzofuran (DBF) and fluorene (FLE) were selected as model compounds because they were the dominant PAHs found in the field-contaminated soil collected from a MGP site. Oxidation kinetics of these PAHs in an artificially contaminated soil and the PAH-contaminated field soil were investigated. For all soils, Fe(0) was the most effective iron activator. The maximum PAHs removal rate in Fe(0)-mediated reactions was 92.7% for ANE, 83.0% for FLE, and 59.3% for DBF in the artificially contaminated soil, while the removal rate of total PAHs was 72.7% in the field-contaminated soil. To promote the iron activator effect, the effects of hydroxylamine as a reducing agent on reduction of Fe<sup>3+</sup> to Fe<sup>2+</sup>, and EDTA and pyrophosphate as chelating agents on iron stabilization in persulfate oxidation were also investigated. As hydroxylamine and chelating agents (EDTA, pyrophosphate) dosage increased, the individual PAH removal rate in the artificially contaminated soil and the total PAHs removal rate in the field-contaminated soil increased.
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Fastener 토크 체결시 발생하는 Chatter현상에 대한 고찰
박창언(Changeon Park),김진호(Jinho Kim),박정도(Jungdo Park) 한국자동차공학회 2014 한국자동차공학회 학술대회 및 전시회 Vol.2014 No.11
Based on the torque verification test for the chassis’s critical joints, we sometimes find out the chatter phenomenon for the bolted parts, when developing new car programs or tightening the fastener at the assembly plant. This paper focus on the cause and effects of the chatter for the joints. Because the chatter phenomenon can affect the durability and clamping load of the fastened joints, we mainly consider the quality of tightening all the vehicle’s clamped parts to prevent each part from chattering at assembly plant. Especially, the chatter sometimes comes out at the clevis-type joints during contacting between the fastener’s bearing surface and opposite clamped surface. So, we need to explain the relation of chatter-clevis joint and test methods. Furthermore we analyze the preventive measurement for the chatter that we keep that phenomenon stopping.
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안화실 ( An Hwasil ),박정도 ( Park Jungdoe ) 한국소년정책학회 2013 少年保護硏究 Vol.23 No.-
More than 99,9% populations and 84% of youths in Korea possess smartphone. The frequent use of information and communication technology(ICT) has brought advantages and disadvantages to mankind. One side effect is the rapid, severe, and increase of cyberbullying among adolescents. This article offers an overview of current state of researches regarding cyberbullying in Korea since 2002. In this article we reviewed the current 31 studies in Korea, which are used 'cyberbullying', 'cyber bullying', 'cyberviloence', 'cyber violence'. There are four categories of analysis: prevalence, factors, responding strategy, and exception. Also cyberbullying is based on one approach which is an additional setting for traditional bullying. We conclude with a discussion of characteristics of articles by outlining several ares of concern in cyberbullying research. There is a lack of knowledge about cyberbullying characteristics and a need for investigating cyberspace. Additionally we propose in an effective and efficient way that can be anti-bullying training, media-literacy, cyber ethic education for youths in order to inform reducing and tackling cyberbullying.
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중속용 Dual Fuel엔진의 윤활유에 관한 실험적 연구
홍성호(Sung-Ho Hong),박창훈(Chang-Hoon Park),박정도(Jungdo Park),Chen Eddie 한국트라이볼로지학회 2016 한국윤활학회지(윤활학회지) Vol.32 No.3
We performed an experimental research on lubricant oil in dual fuel medium-speed engines. It is important to select the appropriate lubricant oil because it could significantly affect engine lifetime and performance. We generally recommend the selection of the lubricant oil according to the fuel grades as contents in the project guide. However, it is a considerable challenge for shipyards to implement this concept because of the lack of space to install the complicated lubricating oil system for dual fuel engines. Therefore, we determine the adaptability of one-common lubricant oil for HiMSEN dual fuel engine through this experimental research. To check abnormality in gas mode operation and durability of engine components when a lubricating oil with high BN (base number) is used, overhaul inspections and lubricant oil analysis are carried out two times, and four times, respectively, during an operation of approximately 300 h. We investigated the variations in kinematic viscosity, base number, element quantity, pentane insoluble and sulfated ash in lubricant oil analysis. Moreover, we also investigated whether the deposit formation or wear occurred in various bearings, injectors, exhaust valves, intake valves, piston rings and so on through the overhaul inspections. There are no problems in the lubricant analysis and the overhaul inspections. Through the experimental research, we confirm that one-common lubricant oil should be selected according to the higher sulfur content of fuel oil in dual fuel engines.
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