• Journal of the Korean Association of Geographic Information Studies
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• v.10 no.4
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• pp.97-110
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• 2007

A laser scanning technique has been attracting much attention as a new technology to acquire location information. This technique might be applicable to a wide range of areas, most notably in geomatics, due to its high accuracy of location and automation of high-density data acquisition. A alignment information extraction system on highway has been developed in this study by utilizing the advantages of the laser scanning technique. The system can accurately interpret the alignment information of highway and can be applied to actual works. To develop the alignment information extraction system on highway, an algorithm that can automatically separate a horizontal alignment into a straight line, a transition curve, and a circular curve was developed. It can increase its efficiency compared to the conventional methods. In addition, an algorithm that can automatically extract design elements of horizontal and vertical alignments of highway was developed and applied to an object highway. This yielded higher practicality with more accurate values compared to those from previous studies on the extraction of design elements of highway alignment. Furthermore, the extracted design elements were used to perform a virtual driving simulation on the object highway. Through this, data were provided for a visual judgment for judging visually whether the topography and structures were harmonized in a three-dimensional manner or not. The study also presents data that can serve as a basis to determine highway surface freezing sections and to analyze three-dimensional sight distance models. Through the establishment of a systematic database for diverse data on highway and the development of web-based operating programs, an efficient highway maintenance can be ensured and also they can provide important information to be used when estimating a highway safety in the future.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.4
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• pp.177-183
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• 2016

Sewage treatment using microorganisms is affected by multiple factors such as microbial properties, characteristics of sewage and operating conditions, and nanoparticles inflow may cause negative effects on sewage treatment system especially on the system stability and efficiency. It was studied to assess the toxic effects of nanoparticles on microorganism growth. The activated sludge in the sewage treatment plant of university was cultured in the optimized medium for each strain. Bacillus (gram-positive), Pseudomonas and E.coli (gram-negative) in the activated sludge were selected as target microorganisms, and ZnO and $TiO_2$ were chosen as nanoparticles. For same concentration of nanoparticles, average growth inhibition rate of Bacillus was 60% or more, while that of Pseudomonas was less than 10%. The toxicity of nanoparticles was shown to be higher for gram-positive bacteria than gram-negative bacteria because of their differences on structure of cell wall, components of cell wall protein, physiology of cells and metabolism. ZnO affected 3 times more negative on the growth of microorganisms as compared to $TiO_2$. It was assumed that, therefore, toxicity of ZnO was found to be greater than $TiO_2$.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.4
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• pp.204-209
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• 2015

The effluent limit of nickel from electroplating wastewater has been strengthened from 5 mg/L to 3 mg/L from 2014. However, currently applied treatment process for nickel plating wastewater is unable to meet the effluent limit, most of the treatment concept conducted by treatment plant is dilution with other metal bearing wastewater. This can cause very significant impact to the environment of nickel contamination. With this connection, the feasibility test has been conducted with the use of electrolysis by using sacrificial electrodes. Experiments were conducted in synthetic and electroless nickel plating wastewater. Optimal condition of current density, pH were derived from the synthetic wastewater. It was found that the removal efficiency of nickel exceeded 94% at the operation condition of at pH 9 and the current density of $1{\sim}2mA/cm^2$. At this conditions, the iron sludge was generated very low amount. However, it was unsuccessful to meet the effluent limit by applying these treatment conditions to the real electroplating wastewater. This can be explained due to the matrix effect of other metals and anions contained real electroplating wastewater. From the result of further study, the optimal conditions for the real wastewater treatment were found out to be at pH 9, current density $6{\sim}7mA/cm^2$, for 5 minutes of operating time. At these conditions, 88% removal of nickel was achieved, which results the residual nickel concentration was below 3 mg/L.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.12
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• pp.689-695
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• 2015

A biofilm filtration for the removal of gaseous pollutants has been recognized as a process with a complex interaction between the gas flow characteristics and the process operating variables. This study aims to develop an one dimensional dynamic numerical model which can be utilized as a tool for the analysis of biofilm filtration process operated in plug flow mode. Since, in a plug flow system, minor environmental changes in a gaseous unit process cause a drastic change in reaction and the interaction between the pollutants is an influencing factor, plug flow system was generalized in developing the model. For facilitation of the model development, dispersion was simplified based on the principles of material balance. Several reactions such as competition, escalation, and control between the pollutants were included in the model. The applicability of the developed model was evaluated by taking the calibration and verification steps on the experimental data performed for the removal of BTX at both low and high flow concentration. The model demonstrated a correlation coefficient ($R^2$) greater than 0.79 under all the experimental conditions except for the case of toluene at high flow condition, which suggested that this model could be used for the generalized gaseous biofilm plug flow filtration system. In addition, this model could be a useful tool in analyzing the design parameters and evaluating process efficiency of the experiments with substantial amount of complexity and diversity.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.12
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• pp.1255-1261
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• 2008

In this study, The effects of three different biological activated carbon (BAC) materials (each coal, coconut and wood based activated carbons), empty bed contact time (EBCT) and water temperature on the removal of haloacetic acid (HAA) 5 species in BAC filters were investigated. Experiments were conducted at three water temperatures (5, 10 and 20$^{\circ}C$) and four EBCTs (5, 10, 15 and 20 min). The results indicated that coal based BAC retained more attached bacterial biomass on the surface of the activated carbon than the other BAC, increasing EBCT or increasing water temperature increased the HAA 5 species removal in BAC columns. To achieve an HAA removal efficiency 50% or higher in a BAC filter, the authors suggest 10 min EBCT or longer for 5$^{\circ}C$ waters and 5 min EBCT for waters at 10$^{\circ}C$ or higher. The kinetic analysis suggested a first-order reaction model for HAA 5 species removal at various water temperatures (5, 10 and 20$^{\circ}C$). The pseudo-first-order reaction rate constants and half-lives were also calculated for HAA removal at 5, 10 and 20$^{\circ}C$. The pseudo-first-order reaction rate constants and half-lives were also calculated for HAA 5 species removal at 5$\sim$ 20$^{\circ}C$. The half-lives of HAA 5 species ranging from 0.75 to 18.58 min could be used to assist water utilities in designing and operating BAC filters for HAA removal.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.10
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• pp.1021-1027
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• 2008

In this study, biofilm process was introduced for treating nonpoint source pollutants. The ceramic media were provided for biofilm growth in the reactors. The packing ratio of ceramic media was 5% and 15(v/v)%, respectively. Thereafter, the reactors were operated intermittently with the different interevent periods such as 0, 5, 10 and 15 days, respectively. The removal efficiencies of COD and NH$_4{^+}$-N were investigated at the different operating conditions such as media packing ratio, temperature, and interevent period. Additionally, Polymerase chain reaction(PCR)-denaturing gel gradient electrophoresis(DGGE) and INT-dehydrogenase activity(DHA) test were conducted to observe the microbial community and activity in the biofilm. Consequently, the interevent period seemed to have no significant influence on the COD removal efficiency. COD was removed within 6$\sim$8 hours at 25$^{\circ}C$ and about 15 hours at 10$^{\circ}C$. DGGE profiles showed that the initial species of microorganisms were changed from seeded activated sludge into the microorganisms detected in sediments. INT-DHA test also showed that the activities of microorgnaisms were not decreased even in the 15 days of interevent period.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.12
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• pp.1273-1280
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• 2008

This study sought to establish the optimum operating condition for the recovery of caustic (NaOH) solution from mercerization in textile process. As main factors, the silt density index (SDI) evaluation of ceramic membrane for the application of nanofiltration/reverse osmosis (NF/RO) membrane, the recovery yield measurement of caustic solution for the application of polymeric membrane, the optimum condition of chemical cleaning for the membrane regeneration, the optimum removal condition of total organic carbon (TOC), turbidity, color, and the permeate flux of ceramic membrane/polymeric membrane combined process were investigated. As results, ceramic ultrafiltration (UF) in the first step and nanofiltration (NF) in the second step were found to be suitable for the removal of total suspended solid (TSS), residual organics, turbidity including color, and the recovery of caustic solution from caustic wastewater stream in mercerization process. When only the ceramic UF membrane was used, the rejection efficiency of both of TSS and turbidity was more than 99.0%, and the color and TOC were rejected about 74.7% and 49.2%, respectively. Meanwhile, the combined membrane precess of UF and NF membranes showed even more efficient removal abilities and thus more than 99.9% of TSS and turbidity, 87.7% of color, and 78.2% of TOC were removed. In particular, 91.3% of NaOH was successfully recovered with 83.7% of total volume in the combined membrane process. With this regard, a clean caustic solution was obtained in a high purity, which can be reused for mercerization process, expecting to offer economical benefits.

• Journal of Biosystems Engineering
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• v.6 no.1
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• pp.60-72
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• 1981

This study was carried out to find out the effects of the sheaf size of paddy harvested by the binders on the threshing performance, load characteristics and power requirement of an auto-feed thresher. The results of the study are summarized as follows: 1. The seperating performance of the thresher appeared to be satisfactory for all the sheaf sizes although the amount of rubbishes and empty grains slightly increased with the sheaf size of paddy. 2. There was no significant difference in grain output quality of the thresher among the three sheaf sizes. However, the amount of grains left unthreshed increased with the sheaf size. In the case of the largest sheaf size with the feed rate of 780kg/h, it exceeded the limit set by the national inspection regulations. 3. The position of the feed-chain rail gave a significant effect on the power requirement of the thresher. At the feed rate of 780kg/h, the net power required to convey sheafs through the feed chain was in the range of 0.37 to 0.50 PS for the middle and lowest position of feed-chain rail, and there was no significant difference among the sheaf sizes. At the highest position, however, it appeared that the smallest sheaf required more power than the others. The net power requirements at this position were 1.03, 0.59. 0.65 PS for the smallest, medium and largest sheafs respectively. 4. The torques of both the thresher and the engine shaft increased with the feed rate and were not affected by the sheaf size for the lower two feed rates of 520 and 780kg/h. At the highest feed rate of 1,040 kg/h, however, they were affected by the sheaf size. In this case, the medium sheaf size gave lower values than the others. 5. The variations in the thresher and the engine torque increased with the feed rate and were not affected by the sheaf size for the feed rate of 520kg/h. At the feed rate of 780kg/h, however, they increased with sheaf size. And at the feed rate of 1,040 kg/h, the torque variations increased greatly for all the sheaf sizes due to an over-load operating condition. 6. It appeared that the average and maximum power requirements of the thresher increased with the feed rate. But, there was no significant difference in power requirement among the sheaf sizes for the lower two feed rates. 7. The threshing efficiency of the thresher was in the range of 214-249 kg/ps.h with the feed rates of 520 and 780 kg/h, and it was not affected by both the sheaf size and the feed rate. At the feed rate of 1,040 kg/h, however, it decreased to as low as 171-174 kg/ps.h because of a sudden increase in power requirement. 8. The average power requirements of the engine were slightly higher than those of the thresher due to the slippage of flat belt between the thresher and engine. It appeared that power transmission from the engine to the thresher was maintained properly since slippages were moderately low with the range of 2.78 to 6.51% throughout the tests. 9. The specific fuel consumption of the engine (diesel 8PS) decreased as the feed rate increased. However, there was no significant reduction in specific fuel consumption as the feed rate increased above 780 kg/h.

• International Journal of Highway Engineering
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• v.14 no.3
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• pp.151-162
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• 2012

It is not surprising to hear news about irresistible natural disasters all over the world due to climate change. Korean Government has focused on developing a variety of green technologies to reduce green house gasses, in particular, carbon dioxide. This study suggested 18 technology divisions for achieving green highway technology development in six different sub-sectors considering life-cycle of roadway and surveyed 29 highway and/or transportation professionals of three institutes using AHP(Analytical Hierarchy Process) analysis to construct "Green Highway"and realize carbon emission reductions and energy use efficiency in a road sector in Korea. Expert Choice Software was used to rank 18 technology divisions weighted by two-level choices. Transport Operating Infrastructure Improvement, Roadway Policy Implementation, Green Transportation(such as Pedestrian and Bicycle) were highly ranked by respondents according to results of the AHP modeling. Among the 18 divisions, technology policy for supporting R&D investments from development to commercialization was ranked as the most significant one to be focused. Green Transportation Facility Design/Construction/Operation and Eco-Friendly Roadway Plan were followed as expected since professionals have thought that the planning/design step of the life-cycle is a starting point to reduce carbon dioxide from roads more and more. Additionally, comparing the results with the Government investment trend 2006-2011 for the roads, it can be interpreted that the Government should invest to the R&D area more widely than before to promote element and core technology development for Green Highway Construction. Above all, small and mid-sized businesses have to be invested as well as encouraged to undertake green highwayrelated objects to accomplish the divisions which ranked high.

• Journal of Korean Society of Transportation
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• v.36 no.2
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• pp.67-85
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• 2018

Vehicle platooning through wireless communication and automated driving technology has become realized. Platooning is a technique in which several vehicles travel at regular intervals while maintaining a minimum safety distance. Truck platooning is of keen interest because it contributes to preventing truck crashes and reducing vehicle emissions, in addition to the increase in truck flow capacity. However, it should be noted that interactions between vehicle platoons and adjacent manually-driven vehicles (MV) significantly give an impact on the performance of traffic flow. In particular, when vehicles entering from on-ramp attempt to merge into the mainstream of freeway, proper interactions by adjusting platoon size and inter-platoon spacing are required to maximize traffic performance. This study developed a methodology for establishing operational strategies for truck platoonings on freeway on-ramp areas. Average speed and conflict rate were used as measure of effectiveness (MOE) to evaluate operational efficiency and safety. Microscopic traffic simulation experiments using VISSIM were conducted to evaluate the effectiveness of various platooning scenarios. A decision making process for selecting better platoon operations to satisfy operations and safety requirements was proposed. It was revealed that a platoon operating scenario with 50m inter-platoon spacing and the platoon consisting of 6 vehicles outperformed other scenarios. The proposed methodology would effectively support the realization of novel traffic management concepts in the era of automated driving environments.