• Journal of Korean Society of Environmental Engineers
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• v.38 no.6
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• pp.291-298
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• 2016

Electrochemical water treatment process as a useful treatment method for the removal of non-degradable matter has been consistently studied for several decades. Key process of electrochemical water treatment are oxidation reaction from an anode and reduction from a cathode. In this study, the effect of pre-treatment methods in the insoluble electrode manufacturing process for the water treatment has been evaluated for the life time of electrode The results of this study showed that pre-treatment methods of a base metal such as surface roughness, clean method and interlayer formation influenced to life time of electrode when the same condition (catalyst electrode layer coating method and material system) was applied for pre-treatment methods. This study was conducted by using $IrO_2/Ti$ electrode In the test of sand-blasting process, an electrode manufactured by using sanding media of different sizes resulted in the most effective electrode life time when the size of alumina was used for $212{\sim}180{\mu}m$ praticle size (#80). The most effective method was considered using arc plasma in the additional roughness control and cleaning process, sputtering method to form Ta type interlayer formation process.

• Journal of Broadcast Engineering
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• v.6 no.3
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• pp.246-259
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• 2001

Due to recent rapid deployment of Internet streaming service and digital broadcasting service, the issue of how to efficiently support streaming workload in so called "Internet Home Appliance" receives prime interests from industry as well as academia. The underlying dilemma is that it may not be feasible to put cutting edge CPU, boards, disks and other peripherals into that type of device. The primary reason is its cost. Usually, Internet Home Appliances has its dedicated usage, e.g. Internet Radio, and thus it does not require high-end CPU nor high-end Va subsystem. The same reasoning applies to I/O subsystem. In Internet Home Appliances dedicated to handle compressed moving picture, it is not equipped with high end SCSI disk with fast rotational speed. Thus, it is mandatory to devise elaborate software algorithm to exploit the available hardware resources and maximize the efficiency of the system. This paper presents our experiences in the design and implementation of a new multimedia file system which can efficiently deliver the required disk bandwidth for a periodic I/O workload. We have implemented the file system on the Linux operating system, and examined itsperformance under streaming I/O workload. The results of the study show that the proposed file system exhibits superior performance than the Linux Ext2 file system under streaming I/O workload. The result of this work not only contribute to advance the state f art file system technology for multimedia streaming but also put forth the software which is readily available and can be deployed. deployed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.6
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• pp.585-595
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• 2017

This study investigates how the emotion-based learning motivation enhancement program influences learning motivation and social support of college students. The developed final program consists of Learning Motivation I, Learning Coaching, and Learning Motivation II, which has 12 sessions. In each session, every student was guided to have reflection time by writing self-evaluation and reflection paper. The participants were 38 students majoring in engineering at K-college located in G city who took one liberal arts subject based on psychology during the 1st semester in 2016 and who were divided into an experimental group (19 students) and a control group (19 students) by non-probability sampling method. In the experimental group, emotion-based learning motivation enhancement program was totally processed 12 times, one class in a week, by one main lecturer and one assistant lecturer. For data analysis, independent sample t-tests, paired samples t-tests, and review analysis were conducted. The study results are as follows. First, the experimental group participating in emotion-based learning motivation enhancement program had more significant differences in learning motivation, and both self-confidence and self-contentment among sub-components than the control group. Second, the experimental group had no significant differences in social support, compared with the control group. The impression writing analysis of the experimental group showed that this program affected learning motivation and social support. Lastly, the study discussions and implications are described.

• Journal of the Korean Wood Science and Technology
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• v.41 no.6
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• pp.583-593
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• 2013

The based-catalyzed depolymerization (BCD) of kraft lignin isolated from black liquor which the chemical pulping of a mixture of various Southeast Asia hardwood chips was carried out in a batch reactor in the presence of different NaOH concentrations with supercritical methanol. The S:G ratio of the kraft lignin determined by pyrolysis-GC/MS analysis turned out roughly 1.4:1 and main products were vanillic acid, syringol and 3-methoxy catechol. The diethyl ether extracts as phenolic monomers from BCD reaction were produced similar yield among different NaOH concentrations. The 21 compounds were identified by GC/MS analysis in all experiments and major products were catechol, 3-methoxycatechol, 4-methylcatechol, syringol and isovanillic acid. However, it had been shown to be different monomer contents depending on the dosage of NaOH. Catechol, 4-methylcatechol and 3-methoxycatechol were shown to be the dominant monomer from BCD reaction using 7.5 and 3.25% of NaOH concentration whereas syringol, isovanillic acid, 3-methoxycatechol and 4-methylcatechol were determined to be the most typical products under the condition of 1.63% NaOH.

• Journal of the Korean Wood Science and Technology
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• v.47 no.6
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• pp.709-720
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• 2019

Due to global warming and abnormal climate, the incidence and scale of green tracts in rivers and water intake dam are increasing every year. Therefore, in this study, developed eco friendly positively charged Torrefied Wood Flour(TWF) coagulant by reusing wood damaged by blight as a natural material. In order to evaluate the effect of coagulant on water ecosystem, green algae contaminated water was collected and TOC showed high removal rate of 86% ~ 92% under 1% and 5% TWF C-PAM treatment condition. The $NH_3-N$ showed 53% removal efficiency. The average pH of the polluted water was 7.9 in the case of hydrogen ion concentration, and the pH of the treated water was in the range of 6.5 ~ 7.7, It was found to be suitable for water quality standards. In ecotoxicity tests, all the results of the experiment showed that both the number of green algae and that of treated water were not affected by the survival of the daphnia. Therefore, as a result of the analyzing, developed paste type TWF coagulants is considered to be able to remove algae using natural resources.

• Journal of the Korean Society of Hazard Mitigation
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• v.11 no.2
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• pp.127-136
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• 2011

In this study, annual maximum storm events are proposed to determined by the return periods considering total rainfall and rainfall intensity together. The rainfall series at Seoul since 1961 are examined and the results are as follows. First, the bivariate exponential distribution is used to determine annual maximum storm events. The parameter estimated annually provides more suitable results than the parameter estimated by whole periods. The chosen annual maximum storm events show these properties. The events with the biggest total rainfall tend to be selected in the wet years and the events with the biggest rainfall intensity in the wet years. These results satisfy the concept of critical storm events which produces the most severe runoff according to soil wetness. The average characteristics of the annual maximum storm events said average rainfall intensity 32.7 mm/hr in 1 hr storm duration(total rainfall 32.7 mm), average rainfall intensity 9.7 mm/hr in 24 hr storm duration(total rainfall 231.6 mm) and average rainfall intensity 7.4 mm/hr in 48 hr storm duration(total rainfall 355.0 mm).

• Journal of Convergence for Information Technology
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• v.11 no.9
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• pp.109-114
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• 2021

Cr(VI)-quinoline compound[(C₉H₇NH)₂Cr₂O₇] was synthesized by the reaction between of quinoline and chromium(VI) trioxide, and structure was FT-IR, elemental analysis. The oxidation ability of benzyl alcohol greatly depends upon the dielectric constant of the used organic solvent, where carbon tetrachloride was worst and N,N'-dimethylformamide was best solvent. Noticeably, in N,N'-dimethylformamide solvent, Cr(VI)-quinoline compound oxidized substituted benzyl alcohols. The Hammett reaction constant(ρ)=-0.69(303K). As a resuit, Cr(VI)-quinoline compound was found as efficicent oxidizing agent that converted benzyl alcohol, allyl alcohol, primary alcohol and secondary alcohols to the corresponding aldehydes or ketones. Cr(VI)-quinoline compound was selective oxidizing agent of benzyl alcohol, allyl alcohol and primary alcohol in the presence of secondary alcohol ones.

• Journal of Internet Computing and Services
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• v.20 no.4
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• pp.81-90
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• 2019

Since 2015, the government has been striving to strengthen the software capabilities required for future talent through software-oriented university in Korea. In the university selected as a software-oriented university, basic software education is given to all departments such as humanities, social science, engineering, natural science, arts and the sports within the university in order to foster convergent human resources with different knowledge and software literacy. In this paper, we analyze the contents of basic software education for twenty universities selected as software-oriented universities. As a result of analysis, most of the basic software education which is carried out to the students of the non-majors students was aimed at improvement of problem solving ability centered on computational thinking for future society and improvement of convergence ability based on computer science. It uses block-based educational programming language and text-based advanced programming language to adjust the difficulty of programming contents and contents reflecting characteristics of each major. Problem-based learning, project-based learning, and discussion method were used as the teaching and learning methods for problem solving. In the future, this paper will help to establish the systematic direction for basic software education of non-majors students.

• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.7
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• pp.926-932
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• 2017

Image distortion can occur when photographing deep sea targets with an optical camera. This problem arises because sunlight is not sufficiently transmitted due to seawater and various floating particles of dust. Particularly, color distortion takes place, causing green and blue color channels to be over emphasized due to water depth, while distortion of boundaries also occurs due to light refraction by seawater and floating particles of dust. These distortions degrade the overall quality of underwater images. In this paper, we analyze underwater images of the bottom of vessels. Based on the results, we propose a technique for color correction and edge enhancement. Experimental results show that the proposed method increases edge clarity by 3.39 % compared to the effective edges of the original underwater image. In addition, a quantitative evaluation and subjective image quality evaluation were concurrently performed. As a result, it was confirmed that object boundaries became clear with color correction. The color correction and contour enhancement method proposed in this paper can be applied in various fields requiring underwater imaging in the future.

• Korean Chemical Engineering Research
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• v.59 no.4
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• pp.521-531
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• 2021

Vacuum Pressure Impregnation (VPI) is a process that enhances physical properties by coating some types of epoxy resins on windings of stator used in large rotators such as generators and motors. During vacuum and pressurization of the VPI process, resin gas is generated by vaporization of epoxy resin. When the tank is opened for curing after finishing impregnation, resin gas is leaked out of the tank. If the leaked resin gas spreads throughout the workplace, there are safety and environmental problems such as fire, explosion and respiratory problems. So, exhaust system for resin gas is required during the process. In this study, a case study of exhaust efficiency by location of vent was conducted using Computational Fluid Dynamics (CFD) in order to design a system for exhausting resin gas generated by the VPI process. The optimal exhaust system of this study allowed more than 90% of resin gas to be exhausted within 1,800 seconds and reduced the fraction of resin gas below the Low Explosive Limit (LEL).