• Safety and Health at Work
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• v.6 no.2
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• pp.90-96
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• 2015

Background: The physical work demands of construction work can be reduced using ergonomic measures. The aim of this study was to evaluate the use of ergonomic measures related to musculoskeletal disorders (MSDs) among construction workers. Methods: A questionnaire was sent at baseline and 2 years later to 1,130 construction workers. We established (1) the proportion of workers reporting an increase in their use of ergonomic measures, (2) the proportion of workers reporting a decrease in MSDs, (3) the relative risk for an increase in the use of ergonomic measures and a decrease in MSDs, and (4) workers' knowledge and opinions about the use of ergonomic measures. Results: At follow-up, response rate was 63% (713/1,130). The proportion of workers using ergonomic measures for vertical transport increased (34%, 144/419, p < 0.01); for measures regarding horizontal transport and the positioning of materials, no change was reported. The proportion of workers reporting shoulder complaints decreased (28%, 176/638, p = 0.02). A relationship between the use of ergonomic measures and MSDs was not found; 83% (581/704) of the workers indicated having sufficient knowledge about ergonomic measures. Lightening the physical load was reported to be the main reason for using them. Conclusion: Only the use of ergonomic measures for vertical transport increased over a 2-year period. No relationship between the use of ergonomic measures and MSDs was found. Strategies aimed at improving the availability of ergonomic equipment complemented with individualized advice and training in using them might be the required next steps to increase the use of ergonomic measures.

• Journal of Advanced Navigation Technology
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• v.21 no.1
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• pp.90-98
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• 2017

This paper is concerned with air traffic controllers' fatigue and stress that they experience during their daily job particularly as being shift workers. Previous researches reveal that the controllers' fatigue and stress increase by several factors including time spent at work, traffic intensity, visibility, etc. The researches also indicate that air traffic controllers' fatigue and stress can be reasonably surrogated by their heart rate. We set three hypotheses relating the influencing factors and the fatigue and stress represented by the heart rates. Using wrist bands, air traffic controllers' heart rates at various situations are collected at Choongju airport. The hypothetical tests explicitly confirm that the heart rate is highly correlated with the traffic level and the time spent at work. In particular, it be shown that even when handling the same traffic level, air traffic controllers' stress level increases as the time they spent at work increases.

• Journal of Korea Society of Industrial Information Systems
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• v.10 no.2
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• pp.76-81
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• 2005

This research approached electrical characteristics of organic light emitting diodes getting into the spotlight by next generation display device. Basic mechanism of OLED's emitting is known as that electron by cathode of lower work function and hole by anode of higher work function are driven and recombine exciton-state being flowed in emitting material layer passing carrier transport layer In order to make many electron-hole pairs, we must manufacture device in multi-layer structure. There are Carrier Injection Layer(CIL), Carrier Transport Layer(CTL) and Emitting Material Layer(EML) in multi-layer structure. It is important that regulate thickness of layer for high luminescence efficiency and set mobility of hole and electron.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.8 no.6
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• pp.98-111
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• 2009

The objective of this study is to revise the related regulations and laws of intelligent transport systems performance tests and methods. This study improves the reliability of present traffic information, reduce public discontent by systematic reforms and reduce national and social costs through the analysis of intelligent transport system performance tests'current status and problems. This study will maximize the investment profits and efficiency of ITS system as the reliability of transportation information which is created through the maintenance of ITS equipment and center, systemization of work responsibility through close analysis of ITS performance test and overall evaluation of role of ITS performance assessment organization will improve and new level of service will be born.

• Journal of computational fluids engineering
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• v.21 no.1
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• pp.19-29
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• 2016

A Prototype Gen-IV Sodium-cooled Fast Reactor which is one of the $4^{th}$ generation nuclear reactors is in development by Korea Atomic Energy Research Institute. The reactor is composed of four main fluid systems which are categorized by its functions, i.e., Primary Heat Transport System, Intermediate Heat Transport System, Decay Heat Removal System and Sodium-Water Reaction Pressure Relief System. The coolant of the reactor is liquid sodium and sodium-to-sodium heat exchangers are installed at the interfaces between two fluid systems, Intermediate Heat Exchangers between the Primary Heat Transport System and the Intermediate Heat Transport System and Decay Heat Exchangers between the Primary Heat Transport System and the Decay Heat Removal System. For the design and performance analysis of the Intermediate Heat Exchanger and the Decay Heat Exchanger, a computer code was written during previous step of research. In this work, the computer code named "SHXSA" has been validated preliminarily by computational fluid dynamics simulations.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.56 no.1
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• pp.1-5
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• 2007

Study on the electron transport coefficient in mixtures of CF4 and Ar, have been analyzed over a range of the reduced electric field strength between 0.1 and 350[Td] by the two-term approximation of the Boltzmann equation (BEq.) method and the Monte Carlo simulation (MCS). The calculations of electron swarm parameters require the knowledge of several collision cross-sections of electron beam. Thus, published momentum transfer, ionization, vibration, attachment, electronic excitation, and dissociation cross-sections of electrons for $CF_4$ and Ar, were used. The differences of the transport coefficients of electrons in $CF_4$ mixtures of Ar, have been explained by the deduced energy distribution functions for electrons and the complete collision cross-sections for electrons. The results of the Boltzmann equation and the Monte Carlo simulation have been compared with the data presented by several workers. The deduced transport coefficients for electrons agree reasonably well with the experimental and simulation data obtained by Nakamura and Hayashi. The energy distribution function of electrons in $CF_4-Ar$ mixtures shows the Maxwellian distribution for energy. That is, $f({\varepsilon})$ has the symmetrical shape whose axis of symmetry is a most probably energy. The proposed theoretical simulation techniques in this work will be useful to predict the fundamental process of charged particles and the breakdown properties of gas mixtures. A two-term approximation of the Boltzmann equation analysis and Monte Carlo simulation have been used to study electron transport coefficients.

• Journal of the Korean Society for Heat Treatment
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• v.35 no.4
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• pp.193-202
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• 2022

Manholes and underground spaces are installed to manage the buried heat transport pipes of the district heating system, and the corrosion damage of the equipment placed in this space often occurs. The purpose of this work is to identify locations with a high risk of corrosion damage in the air vent and to establish preventive measures based on precise analysis via sampling of heat transport pipes and air vents that have been used for about 30 years. The residual thickness of the air vent decreased significantly by reaching ~1.1 mm in thickness, and locations of 60~70 mm away from a transport pipe were the most vulnerable to corrosion. The energy dispersive X-ray spectroscopy (EDS) analysis was performed in the corroded oxides, and it was found that chloride ion was contained in the corrosion products. Anodic polarization tests were carried out on the air vent materials (SPPS250, SS304) with varying the amounts of chloride ions at two different temperatures (RT, 80℃). The higher concentration of chloride ions and temperature are, the lower corrosion resistances of both alloys are.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.2 no.1 s.2
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• pp.1-13
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• 2003

This International Standard establishes an AVI/AEI System based on radio frequency technologies. This system is intended for general application in ITS. Specially, It allows the transfer of the identification codes and further information about equipment and vehicles used in intermodal transport into such CVO and information systems related to Intermodal Transport processes. The aim of this standard is to define, describe and specify Architecture, System Parameters, Numbering/ Data structures and interface related to an AVI/AEI system to provide an enabling Standard, which, whilst allowing the system specifier to determine the performance levels and operating conditions, provides a framework for nominal interoperability. The Standard is to establish a common framework to achieve unambiguous identification in AVI/AEI applications. Thes is AVI/AEI is designed to be an 'enabling' structure to allow interoperability between different commercial systems, and not prescriptive in determining any one system. The ISO TC204 WG4 has eight active work items. A new WI on ERI is progressing quickly; three WIs for the road environment and four multimodal WIs are under development. All Work Items are joint between CEN TC278 and ISO TC204 according to the Vienna Agreement, with CEN in the lead. The work is progressing with some delay. For all the work items, the countries who have appointed experts we: Australia, Austria, Belgium, Canada, Czech, Denmark France, Germany, Japan, Korea, the Netherlands, Norway, Spain, Sweden, UK and USA. There are 30 registered experts. The study focus on the AVI/AEcl standardization and developing of the Korea standard

• Nuclear Engineering and Technology
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• v.52 no.2
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• pp.230-237
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• 2020

In this part, an implicit time dependent solution is presented for the Boltzmann transport equation discretized by the analytic coarse mesh finite difference method (ACMFD) over the spatial domain as well as the simplified P₃ (SP₃) for the angular variable. In the first part of this work we proposed a SP₃-ACMFD approach to solve the static eigenvalue equations which provide the initial conditions for temp dependent equations. Having solved the 3D multi-group SP₃-ACMFD static equations, an implicit approach is resorted to ensure stability of time steps. An exponential behavior is assumed in transverse integrated equations to establish a relationship between flux moments and currents. Also, analytic integration is benefited for the time-dependent solution of precursor concentration equations. Finally, a multi-channel one-phase thermal hydraulic model is coupled to the proposed methodology. Transient equations are then solved at each step using the GMRES technique. To show the sufficiency of proposed transient SP₃-ACMFD approximation for a full core analysis, a comparison is made using transport peers as the reference. To further demonstrate superiority, results are compared with a 3D multi-group transient diffusion solver developed as a byproduct of this work. Outcomes confirm that the idea can be considered as an economic interim approach which is superior to the diffusion approximation, and comparable with transport in results.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.425.1-425.1
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• 2014

Thermal transport in nanomaterials is not only scientifically interesting but also technological important for various future electronic, bio, and energy device applications. Among the various computation approaches to investigate lattice thermal transport phenomena in nanoscale, the atomistic nonequilibrium Green's function approach based on first-principles density functional theory calculations appeared as a promising method given the continued miniaturization of devices and the difficulty of developing classical force constants for novel nanoscale interfaces. Among the nanometerials, carbon atomic chains, namely the cumulene (all-doulble bonds, ${\cdots}C=C=C=C{\cdots}$) and polyyne (alternation of single and triple bonds, ${\cdots}C{\equiv}C-C{\equiv}C{\cdots}$) can be considered as the extream cases of interconnction materials for nanodevices. After the discovery and realization of carbon atomic chains, their electronic transport properties have been widely studied. For the thermal transport properties, however, there have been few literatures for this simple linear chain system. In this work, we first report on the development of a non-equilibrium Green's function theory-based computational tool for atomistic thermal transport calculations of nanojunctions. Using the developed tool, we investigated phonon dispersion and transmission properties of polyethylene (${\cdots}CH2-CH2-CH2-CH2{\cdots}$) and polyene (${\cdots}CH-CH-CH-CH{\cdots}$) structures as well as the cumulene and polyyne. The resulting phonon dispersion from polyethylene and polyene showed agreement with previous results. Compared to the cumulene, the gap was found near the ${\Gamma}$ point of the phonon dispersion of polyyne as the prediction of Peierls distortion, and this feature was reflected in the phonon transmission of polyyne. We also investigated the range of interatomic force interactions with increase in the size of the simulation system to check the convergence criteria. Compared to polyethylene and polyene, polyyne and cumulene showed spatially long-ranged force interactions. This is reflected on the differences in phonon transport caused by the delicate differences in electronic structure.