• Journal of Korea Water Resources Association
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• v.45 no.12
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• pp.1293-1307
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• 2012

This study is to evaluate the RHESSys (Regional Hydro-Ecological Simulation System) simulated streamflow (Q), evapotranspiration (ET), soil moisture (SM), gross primary productivity (GPP) and photosynthetic productivity (PSNnet) with the measured data. The RHESSys is a hydro-ecological model designed to simulate integrated water, carbon, and nutrient cycling and transport over spatially variable terrain. A 8.5 $km^2$ Seolma-cheon catchment located in the northwest of South Korea was adopted. The catchment covers 90.0% forest and the dominant soil is sandy loam. The model was calibrated with 2 years (2007-2008) daily Q at the watershed outlet and MODIS (Moderate Resolution Imaging Spectroradiometer) GPP, PSNnet and 3 year (2007～2009) daily ET data measured at flux tower using the eddy-covariance technique. The coefficient of determination ($R^2$) and the Nash-Sutcliffe model efficiency (ME) for Q were 0.74 and 0.63, and the average $R^2$ for ET and GPP were 0.54 and 0.93 respectively. The model was validated with 1 year (2009) Q and GPP. The $R^2$ and the ME for Q were 0.92 and 0.84, the $R^2$ for GPP were 0.93.

• Journal of Korean Society of Transportation
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• v.21 no.4
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• pp.17-27
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• 2003

In general, an airport access system has influenced on airport terminal operation. The congestion and delay in service facilities at an airport are definitely depended on the patterns of passenger arrival behavior and time spent in a terminal. Therefore, it is necessary to analyze the passenger arrival behavior at an airport to improve the operations at passenger terminal. Passenger arrival patterns to an airport are mainly depended on factors such as the length of access time. reliability of access time. and provision of transport modes, etc. The focus of this paper is to estimate the relationship between the length of access time and passenger's total time spent to board aeroplane. For this, passenger surveys were conducted at the Gimpo International Airport for a large airport and Sacheon Airport for a small size airport. The mathematical relationship between arrival time at an airport prior to the scheduled time of departure(STD) and access time spent was then estimated. It is considered that the results of this study can be used to reduce congestion and delays, thereby to improve the efficiency of the passenger services at the airports.

• Journal of Korean Society of Transportation
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• v.34 no.4
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• pp.304-317
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• 2016

The advancement in technology including transportation and information communication has accelerated the flow of supplies, and the importance of the national logistics policy has increased following the expansion of the regional range of logistics to a national range. The rapid growth of the domestic logistics market results in the deficit of logistics facilities, inefficient operation of logistics facilities, and a complicated distribution structure. It has precipitated a plan aimed at efficiency improvement by building base logistics facilities, but this market is now undergoing difficulties due to low performance. Many studies on the revitalization of base logistics facilities have been conducted, but a causal analysis focusing on the function overlap of private logistics businesses has been absent. Therefore, this study has analyzed the function overlap of logistics facilities and the irrationality of the system, which resulted from the lost function of Inland Freight bases in the Yeongnam region. By suggesting the cause of disuse of base logistics complexes from the function overlap in the ground transportation of domestic freight, the study can provide the policy implication for the national logistics infrastructure.

• Journal of Internet Computing and Services
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• v.17 no.6
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• pp.81-91
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• 2016

VANET is one of the most developed technologies many people have considered a technology for the next generation. It basically utilizes the wireless technology and it can be used for measuring the speed of the vehicle, the location and even traffic control. With sharing those information, VANET can offer Cooperative ITS which can make a solution for a variety of traffic issues. In this way, safety for drivers, efficiency and mobility can be increased with VANET but data between vehicles or between vehicle and infrastructure are included with private information. Therefore alternatives are necessary to secure privacy. If there is no alternative for privacy, it can not only cause some problems about identification information but also it allows attackers to get location tracking and makes a target. Besides, people's lives or property can be dangerous because of sending wrong information or forgery. In addition to this, it is possible to be information stealing by attacker's impersonation or private information exposure through eavesdropping in communication environment. Therefore, in this paper we propose Privacy Assurance Architecture for VANET to ensure privacy from these threats.

• Korean Journal of Soil Science and Fertilizer
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• v.48 no.5
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• pp.397-403
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• 2015

Heavy metals reduce the photosynthetic efficiency and disrupt metabolic reactions in a concentration-dependent manner. Moreover, by replacing the metal ions in metalloproteins that use essential metal ions, such as Cu, Zn, Mn, and Fe, as co-factors, heavy metals ultimately lead to the formation of reactive oxygen species (ROS). These, in turn, cause destruction of the cell membrane through lipid peroxidation, and eventually cause the plant to necrosis. Given the aforementioned factors, this study was aimed to understand the physiological responses of rice to cadmium (Cd) and arsenic (As) toxicity and the effect of essential metal ions on homeostasis. In order to confirm the level of physiological inhibition caused by heavy metal toxicity, hydroponically grown rice (Oryza sativa L. cv. Dongjin) plants were exposed with $0-50{\mu}M$ cadmium (Cd, $CdCl_2$) and arsenic (As, $NaAsO_2$) at 3-leaf stage, and then investigated malondialdehyde (MDA) contents after 7 days of the treatment. With increasing concentrations of Cd and As, the MDA content in leaf blade and root increased with a consistent trend. At 14 days after treatment with $30{\mu}M$ Cd and As, plant height showed no significant difference between Cd and As, with an identical reduction. However, As caused a greater decline than Cd for shoot fresh weight, dry weight, and water content. The largest amounts of Cd and As were found in the roots and also observed a large amount of transport to the leaf sheath. Interestingly, in terms of Cd transfer to the shoot parts of the plant, it was only transported to upper leaf blades, and we did not detect any Cd in lower leaf blades. However, As was transferred to a greater level in lower leaf blades than in upper leaf blades. In the roots, Cd inhibited Zn absorption, while As inhibited Cu uptake. Furthermore, in the leaf sheath, while Cd and As treatments caused no change in Cu homeostasis, they had an antagonist effect on the absorption of Zn. Finally, in both upper and lower leaf blades, Cd and As toxicity was found to inhibit absorption of both Cu and Zn. Based on these results, it would be considered that heavy metal toxicity causes an increase in lipid peroxidation. This, in turn, leads to damage to the conductive tissue connecting the roots, leaf sheath, and leaf blades, which results in a reduction in water content and causes several physiological alterations. Furthermore, by disrupting homeostasis of the essential metal ions, Cu and Zn, this causes complete heavy metal toxicity.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.6
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• pp.864-871
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• 2010

At the current situation of continuous utilization of heavy metal contaminated upland for agricultural purpose in Korea, minimizing transport of heavy metals from soil to crops is important for securing safety of human health. The present study (in field scale) examined the efficiency of several soil amendments (dolomite, steel slag, lime, zeolite, and compost) on reduction of phytoavailable heavy metals (Cd, Cu, Pb, and Zn) in soil through comparison with no amendment treatment and clean soil cover treatment. For determination of the phytoavailability, 1 M $NH_4NO_3$ extraction and red pepper cultivation were introduced. Among the amendments, in general, dolomite and steel slag were the most effective in reduction of metal (Cd, Pb, and Zn) phytoavailability resulting in less accumulation of these metals in shoot and fruit of red pepper. However, dolomite and steel slag treatment was not as effective as clean soil cover treatment which showed the least metal accumulation in red pepper fruit. Nevertheless, with taking into account the cost, treatment of dolomite or steel slag can be competitive method because the current study showed that dolomite or steel slag treatment reduced accumulated heavy metal concentration effectively in both shoot and fruit of red pepper compared to those from control soil and the concentration in fruit was within the standard value (<0.2 mg $kg^{-1}$ for both Cd and Pb).

• Journal of Korean Tunnelling and Underground Space Association
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• v.24 no.6
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• pp.637-658
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• 2022

TBM tunnel is simple with the iterative process of excavating the ground, building a segment ring-build, and backfilling. Drill & Blast, a conventional tunnel construction method, is more complicated than the TBM tunnel and has some restrictions because it repeats the inspection, drilling, charging, blasting, ventilation, muck treatment, and installation of support materials. However, the preparation work for excavation requires time and cost based on a very detailed plan compared to Drill & Blasting, which reinforces the ground and forms a tunnel after the formation of tunnel portal. This is because the TBM equipment for excavating the target ground determines the success or failure of the construction. If the TBM, an expensive order-made equipment, is incorrectly configured at the assembly stage, it becomes difficult to excavate from the initial stage as well as the main excavation stage. When the assembled shield TBM equipment is dismantled again, and a situation of re-assembly occurs, it is difficult throughout the construction period due to economic loss as well as time. Therefore, in this study, the layout and plan of the site and the assembly process for each major part of the TBM equipment were reviewed for the assembly of slurry shield TBM to construct the largest diameter road tunnel in domestic passing through the Han River and minimized interference with other processes and the efficiency of cutter head assembly and transport were analyzed and improved to suit the site conditions.

• Journal of the Korea Organic Resources Recycling Association
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• v.27 no.1
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• pp.77-85
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• 2019

Biogasification is a technology that uses organic wastes to reproduce as environmental fuels containing methane gas. Biogasification has attracted worldwide attention because it can produce renewable-energy and stable land treatment with prohibit from landfilling and ocean dumping of organic waste. Biomethane is produced by refining biogas. It is injected into natural gas pipeline or used transportation fuel such as cars and buses. 90 bio-gasification facilities are operating in 2016, and methane gas production is very low due to it is limited to organic wastes such as food waste, animal manure, and sewage sludge. There are seven domestic biomethane manufacturing facilities, and the use of high value-added such as transport fuels and city-gas through upgrading biogas should be expanded. On the other hand, the rapid biogasification of organic wastes in domestic resulted in frequent breakdowns of facilities and low efficiency problems. Therefore, the problem is improving as technical guidance, design and operational technical guidance is developed and field experience is accumulated. However, while improvements in biogas production are being made, there is a problem with low utilization. In this study, the problems of biomethane manufacturing facilities were identified in order to optimize the production and utilization of biogas from organic waste resources. Also, in order to present the design and operation guideline of the gas pretreatment and the upgrading process, we will investigate precision monitoring, energy balance and economic analysis and solutions for on-site problems by facility.

• Korean Journal of Construction Engineering and Management
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• v.20 no.1
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• pp.52-61
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• 2019

On 30 June, 2017, the Ministry of Land, Infrastructure, and Transport announced the minimum size of parking section will be expanded in parking lots. The expansion of parking section could lead to increase in apartment prices because of increase in total area of the parking lots. It is necessary to adjust the column spacing and number in the parking lots and to apply the 8-Bay long-span parking module with good parking efficiency. According to the study, the construction cost of the 6-Bay module and 8-Bay module was almost the same. But The 8-Bay module was more economical than the 6-Bay module because of the reduction in total area of 8-Bay multi-moduel. The Result of construction cost of 8-Bay modules, Removal Deck-plate RC system was most economical. While the construction cost of PC system was higher due to increase in volume of the member, it would ensure sufficient economy by reducing the girder height to apply a pre-stress method. Also, the construction cost of hollow slab system was the highest. But it could be used as the underground parking lots for apartment, because it had the lowest cost per square meter. This Study has a academic significance by proving the applicability of the 8-Bay Module to underground parking lot of apartment. And it is expected that this study will be used as basic data to derive optimal construction method that applies 8-Bay Module.

• The Korean Journal of Applied Statistics
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• v.32 no.1
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• pp.111-128
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• 2019

Subways are eco-friendly public transportation that can transport large numbers of passengers safely and quickly. It is necessary to predict the accurate number of passengers in order to increase public interest in subway. This study groups stations on Lines 1 to 9 of the Seoul Metropolitan Subway using clustering analysis. We propose one final prediction model for all stations and three optimal prediction models for each cluster. We found three groups of stations out of 294 total subway stations. The Group 1 area is industrial and commercial, the Group 2 ares is residential and commercial, and the Group 3 area is residential districts. Various data mining techniques were conducted for each group, as well as driving some influential factors on demand prediction. We use our model to predict the number of passengers for 8 new stations which are part of the 3rd extension plan of Seoul metro line 9 opened in October 2018. The estimated average number of passengers per hour is from 241 to 452 and the estimated maximum number of passengers per hour is from 969 to 1515. We believe our analysis can help improve the efficiency of public transportation policy.