• Environmental Engineering Research
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• v.11 no.2
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• pp.84-90
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• 2006

UV-catalytic oxidation technique was applied for the treatment of bio-refractory character of the leachate, which is generally present in the form of adsorbable organic halogens (AOX). Destruction of AOX was likely to be governed by pH adjustment, quantitative measurement of oxidants, and the selection of oxidation model type. Peroxide induced degradation ($UV/H_2O_2$) facilitated the chemical oxidation of organic halides in acidic medium, however, the system showed least AOX removal efficiency than the other two systems. Increased dosage of hydrogen peroxide (from 0.5 time to 1.0 time concentration) even did not contribute to a significant increase in the removal rate of AOX. In ozone induced degradation system ($UV/O_3$), alkaline medium (pH 10) favored the removal of AOX and the removal rate was found 11% higher than the rate at pH 3. Since efficiency of the $UV/O_3$ increases with the increase of pH, therefore, more OH-radicals were available for the destruction of organic halides. UV-light with the combination of both ozone and hydrogen peroxide ($UV/H_2O_2$ 0.5 time/$O_3$ 25 mg/min) showed the highest removal rate of AOX and the removal efficiency was found 26% higher than the removal efficiency of $UV/O_3$. The system $UV/H2O_2/O_3$ got the economic preference over the other two systems since lower dose of hydrogen peroxide and relatively shorter reaction time were found enough to get the highest AOX removal rate.

• Journal of Korean Society on Water Environment
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• v.36 no.2
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• pp.137-147
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• 2020

A direct contact membrane distillation (DCMD) was applied to treat strong nitrogenous wastewater of anaerobic digestion supernatant (ADS) and human urine (HU). The ammonia transfer was evaluated in terms of specific ammonia transfer (SAT) value, which is the ratio of total ammoniacal nitrogen divided by the amount of water transferred. The acidification resulted in low SAT values and high quality of produced water. The ammonia transfer control in the acidic condition was stronger for HU than ADS due to higher alkalinity (pH 8.8) and ammonia concentration (5700 mg-N/L) of HU. Acidified HU at pH 4 exhibited a SAT value of 1.64 × 10^-5, which was significantly smaller than the SAT value of 3.00 × 10^-3 for the original HU. The low pH enhanced the water flux for ADS, but HU showed a steep decrease in water flux due to enhanced fouling. It was considered that the fouling intensity in acidic conditions depends on the characteristics of the wastewater source. The major foulants on the MD membrane were NaCl, CaCO₃ and CuSO₄ as recognized by the SEM-EDS. Acidified ADS and HU at pH 4 showed relatively high N content of 8.18 % and 28.03 %, respectively, as organic fouling.

• International Journal of Highway Engineering
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• v.19 no.1
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• pp.107-119
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• 2017

PURPOSES : The desire of drivers to increase their driving speeds is increasing in response to the technological advancements in vehicles and roads. Therefore, studies are being conducted to increase the maximum design speed in Korea to 140 km/h. The stopping sight distance (SSD) is an important criterion for acquiring sustained road safety in road design. Moreover, although the perception-reaction time (PRT) is a critical variable in the calculation of the SSD, there are not many current studies on PRT. Prior to increasing the design speed, it is necessary to confirm whether the domestic PRT standard (2.5 s) is applicable to high-speed driving. Thus, in this study, we have investigated the influence of high-speed driving on PRT. METHODS : A driving simulator was used to record the PRT of drivers. A virtual driving map was composed using UC-Win/Road software. Experiments were carried out at speeds of 100, 120, and 140 km/h while assuming the following three driving scenarios according to driver expectation: Expected, Unexpected, and Surprised. Lastly, we analyzed the gaze position of the driver as they drove in the simulated environment using Smarteye. RESULTS : Driving simulator experimental results showed that the PRT of drivers decreased as driving speed increased from 100 km/h to 140 km/h. Furthermore, the gaze position analysis results demonstrated that the decrease in PRT of drivers as the driving speed increased was directly related to their level of concentration. CONCLUSIONS : In the experimental results, 85% of drivers responded within 2.0 s at a driving speed of 140 km/h. Thus, the results obtained here verify that the current domestic standard of 2.5 s can be applied in the highways designated to have 140 km/h maximum speed.

• The Korean Fashion and Textile Research Journal
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• v.19 no.4
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• pp.515-522
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• 2017

The natural dyeing industry has been faced with increasing demands of constant needs for environmentally and body friendly clothing products among modern consumers. Natural dyeing has attracted attention as a next-generation technology in green textiles. Dyestuffs need to be diversified for technological development activation in order to meet the increasing demands for natural dyeing. This study extracted dyeing solutions from the leaves of the Rose of Sharon (the national flower of South Korea) and investigated its dyeing properties for the development of various natural dyestuffs. This study investigates the dyeability of silk fabrics with Rose of Sharon leaves extract. Optimal conditions for dyeing of silk fabrics with the extract of Rose of Sharon were $40^{\circ}C/80min$ and $90^{\circ}C/60min$ with 100% concentration. Looking at the results, it showed the best K/S value at pH3, Sn pre-mordanting and Fe post-mordanting. Color fastness to washing, dry cleaning, rubbing and perspiration was good at grade 4-5 or 4. However, light fastness was observed in grade 2. In aspect of functional property, it showed an excellent result of 90% deodorization rate. In addition, its proven functionalities (deodorant properties) will help to produce high value added environment-friendly products. Those findings demonstrate the possibilities of the Rose of Sharon as an environment-friendly dye.

• Journal of Microbiology and Biotechnology
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• v.24 no.4
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• pp.453-464
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• 2014

The current research was focused on the extracellular biosynthesis of bactericidal silver nanoparticles (AgNPs) using cell-free supernatant of a local isolate previously identified as a novel Streptomyces aegyptia NEAE 102. The biosynthesis of silver nanoparticles by Streptomyces aegyptia NEAE 102 was quite fast and required far less time than previously published strains. The produced particles showed a single surface plasmon resonance peak at 400 nm by UV-Vis spectroscopy, which confirmed the presence of AgNPs. Response surface methodology was chosen to evaluate the effects of four process variables ($AgNO_3$ concentration, incubation period, pH levels, and inoculum size) on the biosynthesis of silver nanoparticles by Streptomyces aegyptia NEAE 102. Statistical analysis of the results showed that the linear and quadratic effects of incubation period, initial pH, and inoculum size had a significant effect (p < 0.05) on the biosynthesis of silver nanoparticles by Streptomyces aegyptia NEAE 102. The maximum silver nanoparticles biosynthesis (2.5 OD, at 400 nm ) was achieved in runs number 5 and 14 under the conditions of 1 mM $AgNO_3$ (1-1.5% (v/v)), incubation period (72-96 h), initial pH (9-10), and inoculum size (2-4% (v/v)). An overall 4-fold increase in AgNPs biosynthesis was obtained as compared with that of unoptimized conditions. The biosynthesized silver nanoparticles were characterized using UV-VIS spectrophotometer and Fourier transform infrared spectroscopy analysis, in addition to antimicrobial properties. The biosynthesized AgNPs significantly inhibited the growth of medically important pathogenic gram-positive (Staphylococcus aureus) and gram-negative bacteria (Pseudomonas aeruginosa) and yeast (Candida albicans).

• Journal of the Korean Institute of Navigation
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• v.18 no.2
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• pp.91-109
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• 1994

Technological and organisational changes in transport system have introduced new dimension into port system development and inter-port competition. The quality of service now required by the customer is costly and not easily provided by small shipping companies and small ports. It has been suggested that in the future container shipping may be concentrated by space-sharing arrangements or actual mergers into the hands of a few mega-operators with the investment potential to provide total logistics networks. In order to compete effectively, high load factors will be essential and port concentration inevitable. A fa-voured few ports will become the load centres and other ports will assume a secondary feeder role. In this study, three questions are raised and attempts are made to answer them : (a) what is the new role of ports today ; (b) why should ports be engaged in this new role ; and (c) how can ports play this new role. In short, a modern port should be a service centre and a logistic platform for international trade and transport-a third generation port. Ports, in particular, have to make every effort to be competitive in the cost and quality of services and to make the port a transport and distribution service centre. For most ports, this is not an option but a must ; an essential requirement for survival in this win or lose situation. The best way to win is to maintain a close contact with port users, listen to them, discuss with them, help them and satisfy them. That is port marketing. Starting from the findings of port marketing, it is es-sential to work out appropriate development plans and marketing targets and to improve port competitive-ness. As an alternative method, a port competitiveness model is suggested, which may help port managers to make appropriate improvements.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.166-166
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• 2010

Recently, TFTs based on amorphous oxide semiconductors (AOSs) such as ZnO, InZnO, ZnSnO, GaZnO, TiOx, InGaZnO(IGZO), SnGaZnO, etc. have been attracting a grate deal of attention as potential alternatives to existing TFT technology to meet emerging technological demands where Si-based or organic electronics cannot provide a solution. Since, in 2003, Masuda et al. and Nomura et al. have reported on transparent TFTs using ZnO and IGZO as active layers, respectively, much efforts have been devoted to develop oxide TFTs using aforementioned amorphous oxide semiconductors as their active layers. In this thesis, I report on the performance of thin-film transistors using amorphous indium gallium zinc oxides for an active channel layer at room temperature. $SiO_2$ was employed as the gate dielectric oxide. The amorphous indium gallium zinc oxides were deposited by RF magnetron sputtering. The carrier concentration of amorphous indium gallium zinc oxide was controlled by oxygen pressure in the sputtering ambient. Devices are realized that display a threshold voltage of 1.5V and an on/off ration of > $10^9$ operated as an n-type enhancement mode with saturation mobility with $9.06\;cm^2/V{\cdot}s$. The devices show optical transmittance above 80% in the visible range. In conclusion, the fabrication and characterization of thin-film transistors using amorphous indium gallium zinc oxides for an active channel layer were reported. The operation of the devices was an n-type enhancement mode with good saturation characteristics.

• Journal of Ship and Ocean Technology
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• v.5 no.1
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• pp.1-13
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• 2001

As Indonesia determines to increase its marine fishery production, the development of tradi-tional boatyards has to be included in the agenda as it will give the local fishing communities a better chance to compete with large capital intensive fishing companies. It will also spread job opportunities evenly throughout the country instead of concentration fishing vessel con- struction in a few large shipyards located primarily on the highly populated island of Java. However development every single boatyard in indonesia would not only be prohibitively ex-pensive, but it would also create social tensions as the introduced technology would not be immediately accepted by the rural societies whose own traditions are still culturally signif-icant. Both these problems can be reduced by developing a collaborative scheme between traditional boatyards and a larger shipyard. The shipyard, with modern facilities, can develop work packages containing knock down components which are then assembled in the tradi-tional boatyards. The work packages are planned and designed so that every component can be assembled with relatively simple tools. Radical changes can be avoided as new techniques can be introduced gradually, responding to the boatyard\\`s own requirements and aspirations. While this manufacturing procedure is conceptually straightforward its efficient implemen-tation is in practice complicated by the fact that each traditional boatyard has unique char-acteristics in terms of labour resources, technological capability, and transportation links. By developing a computer model to simulate the interaction between the main shipyard and small traditional a computer model to simulate the interaction between the main shipyard and small traditional boatyards work packages can be designed that ensure that activities at all manufacturing locations are efficient.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.20 no.5
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• pp.146-156
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• 2021

A smart city refers to an intelligent city solving problems arising from the concentration its population using IT technology. Various services such as safety, transportation, environment, education, and medical care are provided in a smart city. Still, the degree of service experienced by the residents is lower compared to the technological maturity. Hence, the service acceptance intention factor needs to be improved. In this study, User Characteristic and Service Characteristic variables were identified separately to improve the awareness and experience of smart services among citizens of the smart city and analyze the intention of easy service acceptance. Based on the results, the present study is expected to improve citizen's quality of life and form a happy society. This improvement in citizens and society is achieved by drawing active participation from citizens and investments from the government and private enterprise through solving various problems in the city.

• The Journal of the Korea Contents Association
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• v.19 no.2
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• pp.170-185
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• 2019

This study is intended to look into the structural relationship between SCM activity, process innovation and quality performance in small and medium sized enterprisers(SMEs). To achieve this, a survey was empirically carried out to 354 SCM operating officers and managers who perform the SCM activities in small and medium sized manufacturing firms. The results are summarized as follows. Overall, the SCM activity and process innovation had a significant effect on the quality performance, having a structural relationship with the quality performance in SEMs. This implies that the strategic alliance of the SCM activities and competence concentration based on technology development in SEMs can organize the unity through organizational members' information sharing. In other words, when the information integration supports the compatibility and reliability of shared information system by raising technological competence through this, the process innovation can lead to non-financial cost reduction, product quality, delivery compliance and inventory cost reduction as quality performance of the structured process, management and distribution.