• Korean Journal of Construction Engineering and Management
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• v.15 no.2
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• pp.3-11
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• 2014

As the recent construction projects have been carried out as a mixed-use complex project that includes architecture, civil, mechanical, electrical, and landscape, as well as become bigger and high-rise with the increased repetitive works, the TACT technique has received more attention as an effective method for achieving a target completion date by securing the continuous works. Although the TACT technique can maintain a steady flow without the interruption of works in order to utilize the resources of the repetitive works, it can not be considered as the systematic scheduling technique because the schedule computations are not possible as well as a critical path can not be recognized. This paper proposes the applicabilities of scheduling and monitoring the TACT schedule by the BDM technique as comparing and analyzing the methodologies for apartment finish works by the Excel, the Primavera(P6) based on the PDM technique, and the Beeliner based on the BDM technique that is a new networking technique, respectively.

• KIPS Transactions on Computer and Communication Systems
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• v.8 no.12
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• pp.297-304
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• 2019

The technological advances such as communication, sensor, and artificial intelligence lead smart factory construction. Smart factory aims at efficient process control by utilizing data from the existing automation process and intelligence technology such as machine learning. As a result of constructing smart factory, productivity increases, but costs increase. Therefore, small companies try to make a step-by-step transition from existing process to smart factory. In this paper, we have proposed a remote control system that support data collection, monitoring, and control for manufacturing equipment to support the construction of CNC cutting machine based small-scale smart factory. We have proposed the structure and design of the proposed system and efficient sensing data transmission scheme. To check the feasibility, the system was implemented for CNC cutting machine and functionality verification was performed. For performance evaluation, the web page access time was measured. The results means that the implemented system is available level.

• Geophysics and Geophysical Exploration
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• v.21 no.1
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• pp.8-14
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• 2018

For the purpose of maintenance and prevention of earth fill dams against damage from natural hazards, automatic monitoring through various measuring instruments and resistivity survey has been carried out. Reservoirs and embankments have the structural vulnerability on the agricultural usages since most of them were built more than thirty years ago. The main aim to use monitoring method is to verify the safety and integrity of the dam. Resistivity survey can detect potential weaknesses, such as defective zones, anomalous seepages or internal erosion processes. Permanent resistivity monitoring systems were installed at a reservoir, which daily measurements have been taken every 6 hour. Using monitoring data for one year, anomalous seepage and structural defects were clarified for dam safety. Annual water level fluctuations are around 10 m. During their operation, reservoir dams are subject to a never-ending hydraulic load from the reservoir, which over the years may cause changes in the properties of the inner parts of the dam construction. Detailed analysis of the monitoring results was performed and showed that resistivities at most locations have been very stable over the full monitoring period excluding the effects of water fluctuation and seasons. To investigate the detectability of weak zone using the DC resistivity monitoring, numerical modeling with a simplified model for the drainage at a reservoir dam was also performed. The results showed that the seepage zone near drainage in a reservoir dam could be detected by resistivity response change.

• International conference on construction engineering and project management
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• 2024.07a
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• pp.343-350
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• 2024

Mobile electroencephalography (EEG) can continuously and objectively monitor construction workers' psychological stress, thereby contributing to enhanced safety and health. Traditional EEG-based stress assessment techniques utilize headset-type devices that cover the scalp, including the frontal area, which is the most relevant brain part to stress. Yet, the invasiveness of such devices may pose a potential barrier to their field application. In response, ear-EEG technology presents a less intrusive alternative for continuous monitoring, potentially overcoming the limitations of scalp-EEG. The temporal regions monitored by ear-EEG hold anatomical and functional significance in the brain's response to stress, suggesting that ear-EEG could effectively detect stress. Despite its advantage, the effectiveness of ear-EEG in stress detection remains underexplored, largely due to the existing literature's focus on frontal brain regions. To address this gap, the authors aim to evaluate ear-EEG's effectiveness in measuring stress and compare it to high-density scalp-EEG. EEG signals were collected with ear- and scalp-EEGs from 10 subjects in a controlled laboratory while they performed the mental arithmetic tasks under time pressure and socio-evaluative threats to induce stress at different levels (high vs. low). Subsequently, the authors performed t-tests and point-biserial analysis to analyze differences between high and low-stress conditions in the most reliable stress biomarkers in literature: high-beta power in temporal regions for ear-EEG, and alpha asymmetry in frontal regions for scalp-EEG. The results indicate that both EEG techniques could effectively differentiate between stress levels, with statistical significance (p <0.001 for both) and moderate effect size. Furthermore, the results demonstrate ear-EEG's comparable effectiveness to scalp-EEG in detecting stress-induced brain activity given the comparable statistical metrics, such as p-value and effect size. This study provides a groundwork for further explorations into leveraging ear-EEG as a practical tool for the early detection of stress, aiming to enhance stress management strategies within the construction industry.

• Journal of Environmental Impact Assessment
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• v.22 no.5
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• pp.525-528
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• 2013

River otter(Lutra lutra) are listed as endangered species and Natural monument in Korea, and this study examined the possibility of extinct of river otter in Hongchon river using with the application of Population Viability Analysis (PVA) technique. In Hongchon river areas population was estimated 9 individuals for the last 1999-2005 years and PVA analysis was done for the next 10 years using the average population of 9. Using the initial population the river otter was estimated 30% of extinct for the next 10 years. This estimation was quite low considering water pollution and construction of highways. Also PVA only used population size lacking in other life history information. Nonetheless river otter population can be in risk of extinction if the current construction of crossovers, cement bank are maintained. Long term information regarding life history needs essential.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.11a
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• pp.61-62
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• 2017

In this study, the initiation of steel corrosion was monitored due to chloride attack using embedded sensor. In general, Steel bars embedded in concrete are protected from corrosion by being forming a passive film on the surface. However, the passive film is destroyed by chemical erosion such as concrete carbonation and chloride penetration, and the rebar is exposed to the deteriorating factor and corrosion proceeds. In order to realize the initiation of steel corrosion, OCP and change of Impedance parameter were observed by using Half-cell and EIS method depending on cover depth. As result, 10mm cover showed the impedence increased in 6weeks.

• The Journal of Engineering Geology
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• v.28 no.2
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• pp.313-324
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• 2018

In order to study the earthquake precursor in the Korean peninsula, long-term variations of chemical composition, radon-222, and water level were measured at depths (-60 m, -100 m) in the groundwater monitoring wells of the Daejeon and the Cheongwon area. The pH and electrical conductivity of groundwater in the monitoring wells showed some relationship with the Pohang earthquake. The ${HCO_3}^-$ and $Cl^-$ concentration of groundwater in the Daejeon and $Mg^{2+}$, $Cl^-$ and ${NO_3}^-$ in the Cheongwon showed some relation with the Pohang earthquake. However, it is not distinct to find the relationship between their variation and earthquake. The radon-222 concentration in Daejeon was observed a significant increase from a minimum of 162 Bq/L prior to the earthquake to 573 Bq/L right after the earthquake, that indicating a strong correlation with earthquakes. In the case of groundwater levels, it can not find some correlation between earthquakes and continuous decreasing trend in the monitoring wells of Daejeon and Cheongwon area. However, water level of a national groundwater observation well within 10 kilometers of Pohang epicenter was recorded as an abrupt drop right before the earthquake. Conclusively, although the location of monitoring wells is more than 180 kilometers apart from the epicenter of the Pohang earthquake, the radon gas in groundwater can be considered as a reliable candidate among earthquake precursors. The pH, electrical conductivity, ${HCO_3}^-$ and $Cl^-$ among hydrochemicals showed some correlation with earthquake should be monitored during a longer term to recognize distinctly as a precursor of earthquake.

• International Journal of Highway Engineering
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• v.17 no.6
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• pp.1-9
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• 2015

PURPOSES : The objective of this study is to propose a quality control and quality assurance method for use during asphalt pavement construction using non-destructive methods, such as ground penetrating radar (GPR) and an infrared (IR) camera. METHODS : A 1.0 GHz air-coupled GPR system was used to measure the thickness and in situ density of asphalt concrete overlay during the placement and compaction of the asphalt layer in two test construction sections. The in situ density of the asphalt layer was estimated based on the dielectric constant of the asphalt concrete, which was measured as the ratio of the amplitude of the surface reflection of the asphalt mat to that of a metal plate. In addition, an IR camera was used to monitor the surface temperature of the asphalt mat to ensure its uniformity, for both conventional asphalt concrete and fiber-reinforced asphalt (FRA) concrete. RESULTS : From the GPR test, the measured in situ air void of the asphalt concrete overlay gradually decreased from 12.6% at placement to 8.1% after five roller passes for conventional asphalt concrete, and from 10.7% to 5.9% for the FRA concrete. The thickness of the asphalt concrete overlay was reduced from 7.0 cm to 6.0 cm for the conventional material, and from 9.2 cm to 6.4 cm for the FRA concrete. From the IR camera measurements, the temperature differences in the asphalt mat ranged from $10^{\circ}C$ to $30^{\circ}C$ in the two test sections. CONCLUSIONS : During asphalt concrete construction, GPR and IR tests can be applicable for monitoring the changes in in situ density, thickness, and temperature differences of the overlay, which are the most important factors for quality control. For easier and more reliable quality control of asphalt overlay construction, it is better to use the thickness measurement from the GPR.

• Journal of Korean Society of societal Security
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• v.2 no.3
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• pp.47-53
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• 2009

This study performed the construction of test bed for the combination of the health monitoring system In Yongjong grand bridge with the safety management network system in order to explore the feasibility of combining the existing monitoring system with the safety management network system. For this purpose, connection program which consists of DAQ sender server program and DAQ receiver server program has been developed. DAQ sender server program installed in the connection server, which is located on the DMZ zone of the existing monitoring system, plays the role of communicating with the monitoring system. On the other hand, DAQ receiver server program installed in the connection server, which is located on the integrated operation center of the safety management network system, plays the part of gathering real time and tim history data of the existing monitoring system and storing them in the integrated operation server through the communication with the DAQ sender. Test bed demonstrated the feasibility of combining the existing monitoring system with the safety management network system.

• Korean Journal of Construction Engineering and Management
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• v.5 no.1 s.17
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• pp.88-98
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• 2004

In recent, Information Technology(IT) is the biggest issue on the social whole including the construction industry. IT is recognized as a key strategic means to reinforce competitive power and raise the effectiveness. However, CEOs of each firm have trouble with IT investment decision-making. Because there is neither any case to measure real value of IT nor any confidence to economic effect of information system. IT evaluation is so helpful for most construction firms to make a plan of IT investment. In addition, which will eventually facilitate to achieve their management goal and have the maximum of the firms' value. Therefore, the purpose of this research is to develop IT evaluation system for monitoring IT level continually. And this will be enable a construction company to increase IT investment and improve the level of IT in the construction industry.