• International Journal of Highway Engineering
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• v.3 no.3 s.9
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• pp.147-158
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• 2001

One of the most important factors accounting for the structural capacity of concrete pavement is load transfer efficiency. Load transfer efficiency is affected by slab temperature gradient, construction of dowel bars, degree of aging, and crack width. The purpose of this study is to determine the patterns of load transfer efficiency of concrete pavement; to determine the factors that affect the load transfer efficiency; and to present the proper measuring method of load transfer efficiency. As a result from this study, load transfer efficiency was affected primarily by the average temperature in concrete slab. Load transfer efficiency decreased with decreasing temperature and increasing crack width. For the sections with dowel bars, there were little differences in load transfer efficiency regardless of temperature changes. For the sections without dowel bars, however, there on great losses of load transfer efficiency at low temperatures. For the old pavement, even in the sections with dowel bars, the load transfer efficiency reduced as the temperature dropped For the sections in this study, 1.4% reduction of the load transfer efficiency was observed for each $1^{\circ}C$ drop in the slab temperature.

• Journal of Environmental Health Sciences
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• v.46 no.6
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• pp.719-725
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• 2020

Objectives: With the growth of national interest in fine particulate matter, many complaints about pollutants emitted from air pollution emitting facilities have arisen in recent years. In particular, it is thought that a large volume of particulate pollutants are discharged from workplaces that use Solid Refuse Fuel (SRF). Therefore, particulate contaminants generated from SRF were measured and analyzed in this study in terms of respective particle sizes. Methods: In this study, particulate matter in exhaust gas was measured by applying US EPA method 201a using a cyclone. This method measures Filterable Particulate Matter (FPM), and does not consider the Condensable Particulate Matter (CPM) that forms particles in the atmosphere after being discharged as a gas in the exhaust gas. Results: The mass concentration of Total Suspended Particles (TSP) in the four SRF-using facilities was 1.16 to 11.21 mg/Sm3, indicating a very large concentration deviation of about 10 times. When the fuel input method was the continuous injection type, particulate matter larger than 10 ㎛ diameter showed the highest particle size fraction, followed by particulate matter smaller than 10 ㎛ and larger than 2.5 ㎛, and particulate matter of 2.5 ㎛ or less. Contrary to the continuous injection type, the batch injection type had the smallest particle size fraction of particulate matter larger than 10 ㎛. The overall particulate matter decreased as the operating load factor decreased from 100% to 60% at the batch input type D plant. In addition, as incomplete combustion significantly decreased, the particle size fraction also changed significantly. Both TSP and heavy metals (six items) satisfied the emissions standards. The measured value of the emission factor was 38-99% smaller than the existing emissions factor. Conclusions: In the batch injection facility, the particulate matter decreased as the operating load factor decreased, as did the particle size fraction of the particulate matter. These results will help the selection of effective methods such as reducing the operating load factor instead of adjusting the operating time during emergency reduction measures.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.1120-1122
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• 2002

Switching power supply are widely used in many industrial field. Power factor improvement and harmonic reduction technique is very important in switching power supply. The power factor correction (PFC) circuit using boost converter used in input of power source is studied in this paper. It is analyzed distortional situations and harmonics of input currents that presented at continuous conduction mode(CCM) of boost PFC circuit. It is done simulations of harmonics distribution according to load variation by using PSPICE and MATLAB. From the actual experiment of boost PFC circuit the validity of the analysis is confirmed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.09a
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• pp.19-22
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• 2001

For stabilization and improving power factor in the power lines, various Static Var Compensators(SVC) have been considered to be installed and partly applicated already. With all these merits of the SVC, it stil has demerits, principally evoking harmonic problems. So far, many harmonic reduction type inverters have been used in various parts. In this paper, the reactive power is controlled by amplitude of the output voltage. This paper propose that the multiple voltage source inverter have controllable power factor made by load vary at receive-stage as lagging and leakage control. The theoretical analysis on this system was confirmed through the computer simulation and the experiments.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.2258-2261
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• 2010

Since national mid-term target for GHG reduction was determined in 2009, various efforts in transportations have been prepared. Generally, the GHG emission of transportation is calculated using the emission factor published from IPCC guideline(2006). However, it is necessary to develop new emission factors considering the properties of transportation as well as fuel. In Korean railroad, main emission sources are the consumption of diesel and electricity from railcar operation. The GHG emission of electric-powered railcars can be estimated using national electric emission factor, but diesel-powered railcars show different trends. The purpose of this study was to establish the development plans of emission factors for diesel-powered railcars. As a result, the emission factors of diesel-powered railcars were classified into railcar type, engine type and life cycle, notch, load, and traffic volume. In future, several emission factors with this category will be presented quantitatively through field tests with the order of priority.

• Journal of the Korean Home Economics Association
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• v.31 no.3
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• pp.75-87
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• 1993

The purpose of this study is to analyze the variables related to household work and to find the methods to increase it. The data using in-depth interview method was collected. 30 homemakers were sampled, and the frequency and interview contents were presented. The major findings were as follows: 1. 18 out of 30 interviewees were satisfied with their household work, but they just accepted their given lives. 2. Changes in socialization for woman, general images of household work and women's perception to their work rather than reduction of work load are needed. 3. When women choose the household work as their job, their satisfaction will be increased.

• Journal of Korean Society on Water Environment
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• v.36 no.5
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• pp.385-391
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• 2020

Soil loss is a serious problem frequently caused by local torrential rainfalls due to climate change. In particular, soil loss is occurring in agricultural areas rather than urban areas, and many pollutants are introduced into rivers, causing environmental problems. To reduce soil loss, the Ministry of Environment has designated and managed non-point source management areas. The Jaun-district in Hongcheon-gun, which was designed as a non-point pollution source management area in Gangwon-do, is located in the upper stream of Soyang Lake. Most of the agricultural fields are composed of highland agriculture fields. The highland agricultural fields in the Jaun-district are also composed of large-scale farming areas, and the ditches located near the agricultural fields have been illegally used for farmland. Therefore, the local government in Hongcheon-gun is conducting a project to restore the ditches occupied by agricultural fields. However, an analysis of the amount of soil loss that can be reduced by the restoration of the ditches has not been conducted yet. Thus, the purpose of this study was to analyze the effect of reducing the soil loss from the restoration of the ditches used as agricultural fields in the Jaun-district. The SATEEC L Module was used to analyze the reduction in soil loss by ditch restoration. The SATEEC L Module was constructed to estimate the LS factor using Moore and Burch's method after calculating the slope length using the digital elevation model and the maximum allowable slope length. The LS factor and the USLE formula were used to estimate the amount of soil loss that could be reduced by ditch restoration. The analysis showed that the ditch restoration could reduce about 16.6% of the soil loss in the Jaun-district. The results of this study will contribute to the study of methods to reduce soil loss in non-point pollution management areas.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.2
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• pp.145-152
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• 2015

In the study, the effects of damping devices on damping ratio increase and wind-load reduction were investigated based on the computational platform, which is one of the parametric modeling methods. The computational platform helps the designers or engineers to evaluate the efficacy of the numerous alternative structural systems for irregular Super-Tall building, which is crucial in determining the capacity and the number of the supplemental damping devices for adding the required damping ratios to the building. The inherent damping ratio was estimated based on the related domestic and foreign researches conducted by using real wind-load records. Two types of damping devices were considered: One is inter-story installation type passive control devices and the other is mass type active control devices. The supplemental damping ratio due to the damping devices was calculated by means of equivalent static analysis using an equation suggested by FEMA. The optimal design of the damping devices was conducted by using the computational platform. The structural element quantity reduction effect resulting from the installation of the damping devices could be simply assessed by proposing a wind-load reduction factor, and the effectiveness of the proposed method was verified by a numerical example of a 455m high-rise building. The comparison between roof displacement and the story shear forces by the nonlinear time history analysis and the proposed method indicated that the proposed method could simply but approximately estimate the effects of the supplemental damping devices on the roof displacement and the member force reduction.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.1
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• pp.169-174
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• 2005

The conventional harmonic filters to reduce zero harmonic current from neutral reactors and Zig-Zag connection, have several disadvantages of the decreased reduction rate of harmonics under a light load, because they have the load factor-dependent reduction rate of harmonics, and the risk of potential breaking in the neutral line by heated neutral reactor. Based Zig-Zag connection and Open-Delta mode, this new harmonic eliminating device (HANOS) adopts the combination of Zig-Zag connection and Open-Delta mode-the latter is additionally applied to the transformer's core block for connection to the neutral line. The results of this study demonstrated that the new device could eliminate safely zero harmonic current running in the neutral line without heating.

• The Journal of the Convergence on Culture Technology
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• v.6 no.3
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• pp.443-448
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• 2020

In this study, field measurements were performed to analyze the effects of train types (AREX, AREX Express, KTX, KTX-Sancheon) and train speeds on the dynamic behavior of the direct fixation track structure on Yeongjong grand bridge by bridge type (truss bridge, suspension bridge). Based on field measurement results, the track impact factor and train running stability (coefficient of derailment, Rate of wheel load reduction, lateral displacement of rail head) are compared with domestic and foreign standards and regulations to influence the dynamic behavior of direct fixation track. As a result, the differences in the dynamic behavior of the direct fixation tracks by the type of bridges of Yeongjong bridge are not significant, but it was analyzed that these were more directly affected by the magnitude of the train load. Therefore, it is necessary to establish the reinforcement plan of the direct fixation track structure on Yeongjong grand bridge in consideration of the increase of the track impact factor and dynamic track force.