• Journal of Soil and Groundwater Environment
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• v.23 no.1
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• pp.54-62
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• 2018

This paper is aimed at source tracking of soil heavy metal contamination at a site established by reusing construction wastes. The soil heavy metal concentration at the study site peaked at a depth range of 5-10 m. Column studies were conducted to investigate the possibility of the contamination scenario of infiltration of stormwater carrying heavy metals of ground origin followed by selective heavy metal accumulation at the 5-10 m depth range. Almost all amount of lead, zinc, cadmium, and nickel introduced to the columns each packed with 0-5 m or 5-10 m field soil were accumulated in the column. The very poor heavy metal mobility in spite of the weak association of the heavy metals with the soil (characterized by a sequential extraction procedure) can be attributed to the high pH (10-11) of the construction wastes. From the results, the heavy metal contamination of the subsurface soil by an external heavy metal source was determined to be very unlikely at the study site. The column study applied in the current study is expected to be a useful methodology to present direct evidence of the contaminant source tracking at soil contamination sites.

• Investigative Magnetic Resonance Imaging
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• v.19 no.4
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• pp.212-217
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• 2015

Purpose: For a single time-point hyperpolarized $^{13}C$ magnetic resonance spectroscopy imaging (MRSI) of animal models, scan-time window after injecting substrates is critical in terms of signal-to-noise ratio (SNR) of downstream metabolites. Pre-scans of time-resolved magnetic resonance spectroscopy (MRS) can be performed to determine the scan-time window. In this study, based on two-site exchange model, protocol-specific simulation approaches were developed for $^{13}C$ MRSI and the optimal scan-time window was determined to maximize the SNR of downstream metabolites. Materials and Methods: The arterial input function and conversion rate constant from injected substrates (pyruvate) to downstream metabolite (lactate) were precalibrated, based on pre-scans of time-resolved MRS. MRSI was simulated using two-site exchange model with considerations of scan parameters of MRSI. Optimal scan-time window for mapping lactate was chosen from simulated lactate intensity maps. The performance was validated by multiple in vivo experiments of BALB/C nude mice with MDA-MB-231 breast tumor cells. As a comparison, MRSI were performed with other scan-time windows simply chosen from the lactate signal intensities of pre-scan time-resolved MRS. Results: The optimal scan timing for our animal models was determined by simulation, and was found to be 15 s after injection of the pyruvate. Compared to the simple approach, we observed that the lactate peak signal to noise ratio (PSNR) was increased by 230%. Conclusion: Optimal scan timing to measure downstream metabolites using hyperpolarized $^{13}C$ MRSI can be determined by the proposed protocol-specific simulation approaches.

• Korean Journal of Construction Engineering and Management
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• v.15 no.2
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• pp.122-131
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• 2014

As plant market grows up, client demands to increase quality, technology and to reduce construction period. Due to the vast scale of the construction site and complexity of process, plant project can have some problems of communication among the project participants, the duplication of work, errors and rework. As a result those cause more costs, delay the construction schedule and reduce productivity and quality. Therefore, real-time communication between participants and real-time sharing of information such as material, equipment and construction are required in plant project site. This research aims to propose process and develop system using NFC(Near Field Communication) technology and augmented reality technology with mobile device for plant construction site. Administrators and operators are able to work efficiently using proposed process and system which create an environment designed to share and deliver information such as material, construction information.

• Journal of the Korean Institute of Landscape Architecture
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• v.21 no.4
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• pp.113-129
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• 1994

This study is designed to analyze the trends of professional services in Landscape Architecture during the past 5 years(1987-1991) in Korea. The data were collected from 1,117 projects from 56 engineering and landscape architecture firms. The findings are summarized as follows: 1) The projects have been increased annually by 19 percent in numbers and by 47 percent in money terms. 2) The main sources of projects are local governments and corporations. However the private sector comprise 31 percent in projects number and 46 percent in money terms. 3) The public park and tourism site development comprise a half of the projects. Recently recreational forest, golf, amusement and large housing site development have increased very rapidly. 4) In terms of workscope they are devided by 'complex' project which include extensive engineering works and 'simple' project which contain mostly planting design. The former include receational project with average 5 or 6 months contract period, and the later include housing and building site design with 2 or 3 months period. 5) Two types of consulting firms are typical. One is comprehensive engineering firms with urban planning section and few landscape section. The other is specialized professional firms with urban planning or landscape architecture. 50 percent of the project was done by comhensive engineering firms and 60 percent was done by urban planning section. The implication of these findings are broad: Firstly, We have to meet the demands in private secter mostly in recreation and leisure related projects. Secondly, landscape architects and project managers need more professional skills and coordination ability to deal with 'complex' projects. Thirdly, to enhance the quality of professional services it is required to have enough work time and higher service fee through legal and institutional enforcements.

• Korean Journal of Construction Engineering and Management
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• v.19 no.5
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• pp.101-110
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• 2018

Safety-related accidents are continuously increasing in the construction field. In order to prevent or minimize such accidents, a systematic and active safety activities of on-site managers and workers are required. However, preexisting advance research is lacking on how the safety organization systems are built in construction sites varying in sizes, and how well-trained the related personnel are in safety knowledge and task performances. Especially, a research on the analysis of the formation of their safety knowledge sharing and safety performance cooperation and their visualization is virtually nonexistent. In this regard, this research was conducted with a purpose to study the generalized safety organization method of domestic construction sites, analyze the safety knowledge and cooperation system of the members based on the SNA method and ultimately provide a hands-on data that could be effectively utilized in building an effective safety management system in the future.

• Journal of Soil and Groundwater Environment
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• v.19 no.4
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• pp.52-61
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• 2014

Metal concentrations in the former Janghang smelter area were determined and human health risk of arsenic (As) with bioaccessibility was investigated. Site investigation of the area within 1.5 km from the Janghang smelter showed the As concentrations of 4.8~169.8 mg/kg (avg. 37.8 mg/kg). For 85 samples out of 126 samples, As concentrations were higher than the Worrisome Level of the Korean Soil and Environment Conservation Act, and seven samples exceeded the Countermeasure Standard. Risk assessment for As incorporated with the bioaccessibility revealed that potential human health risk of the carcinogenic ($1.8{\sim}5.0{\times}10^{-5}$) was above the acceptable risk range ($10^{-5}{\sim}10^{-6}$) while the risk of the non-carcinogenic was not found. Remediation goals based on risk incorporated with bioaccessibility of As ranged from 10.8 to 20.0 mg/kg. Such difference in the remediation goals resulted from various bioaccessibility of As (i.e., between 8.7~66.3%) at the study site.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.16 no.12
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• pp.4008-4023
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• 2022

Since machine learning was introduced into cross-site scripting (XSS) attack detection, many researchers have conducted related studies and achieved significant results, such as saving time and labor costs by not maintaining a rule database, which is required by traditional XSS attack detection methods. However, this topic came across some problems, such as poor generalization ability, significant false negative rate (FNR) and false positive rate (FPR). Moreover, the automatic clustering property of graph convolutional networks (GCN) has attracted the attention of researchers. In the field of natural language process (NLP), the results of graph embedding based on GCN are automatically clustered in space without any training, which means that text data can be classified just by the embedding process based on GCN. Previously, other methods required training with the help of labeled data after embedding to complete data classification. With the help of the GCN auto-clustering feature and labeled data, this research proposes an approach to detect XSS attacks (called GCNXSS) to mine the dependencies between the units that constitute an XSS payload. First, GCNXSS transforms a URL into a word homogeneous graph based on word co-occurrence relationships. Then, GCNXSS inputs the graph into the GCN model for graph embedding and gets the classification results. Experimental results show that GCNXSS achieved successful results with accuracy, precision, recall, F1-score, FNR, FPR, and predicted time scores of 99.97%, 99.75%, 99.97%, 99.86%, 0.03%, 0.03%, and 0.0461ms. Compared with existing methods, GCNXSS has a lower FNR and FPR with stronger generalization ability.

• Geomechanics and Engineering
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• v.35 no.4
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• pp.449-464
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• 2023

Advanced nonlinear effective stress constitutive models are started to be frequently used in one-dimensional (1D) and two-dimensional (2D) site response analysis for assessment of porewater generation and liquefaction potential in soft soil deposits. The emphasis of this research is on the assessment of the implementation of this category of models at the element stage. Initially, the performance of a coupled porewater pressure (PWP) and constitutive models were evaluated employing a catalogue of 40 unidirectional cyclic simple shear tests with a variety of relative densities between 35% and 80% and effective vertical stresses between 40 and 80 kPa. The authors evaluated three coupled constitutive models (PDMY02, PM4SAND and PDMY03) using cyclic direct simple shear tests and for decide input parameters used in the model, procedures are recommended. The ability of the coupled model to capture dilation as strength is valuable because the studied models reasonably capture the cyclic performance noted in the experiments and should be utilized to conduct effective stress-based 1D and 2D site response analysis. Sandy soils may become softer and liquefy during earthquakes as a result of pore-water pressure (PWP) development, which may have an impact on seismic design and site response. The tested constitutive models are mathematically coupled with a cyclic strain-based PWP generation model and can capture small-strain stiffness and large-strain shear strength. Results show that there are minor discrepancies between measured and computed excess PWP ratios, indicating that the tested constitutive models provide reasonable estimations of PWP increase during cyclic shear (r_u) and the banana shape is reproduced in a proper way indicating that dilation and shear- strain behavior is well captured by the models.

• Korean Journal of Construction Engineering and Management
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• v.25 no.1
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• pp.13-22
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• 2024

On January 8, 2021, the Act on the Punishment of Severe Disasters passed the Legislation and Judiciary Committee and has been in effect in earnest since January 2022. However, safety accidents at construction sites are still continuing, and it is necessary to discuss ways to improve the safety awareness of construction workers. Therefore, in this study, data were collected through a survey of construction site workers, and the effect of the organizational climate of the workplace on the level of safety consciousness of workers was studied. As a result of the study, the factors of organizational structure, guaranteeing autonomy and consideration of supervisors among the organizational climate of the workplace had a positive effect on the improvement of workers' safety awareness. Based on this, this researcher suggested that workers should be delegated the authority to perform some tasks according to the situation and content of the work during the field work and that incentives should be compensated according to performance.

• 한국생물공학회:학술대회논문집
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• 2003.10a
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• pp.654-654
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• 2003