• Journal of Korean Society on Water Environment
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• v.31 no.5
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• pp.523-532
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• 2015

Hydrocyclone is widely used in industry, for its simple design, high capacity, low maintenance and low operational cost. The objective of this study is to develop hydrocyclone coagulation and filtration system. The system is made of hydrocyclone ballasted coagulation with polyaluminium chloride silicate (PACS) and upflow filter to treat micro particles in urban storm runoff. Roadside sediment particles (< $200{\mu}m$) was mixed with tap water to make various turbid suspensions to simulate urban storm runoff. The filter cartridge was filled with polyethylene media system and ran 1hr per everyday and total operation time were 8.19hrs and backwashing everyday after end of operation. The operation condition of flowrate was $8.2{\sim}11.9m^3/day$ (mean $10.1m^3/day$) and surface overflow rate (SOR) based on filter surface area was $45.5{\sim}65.9m^3/m^2/day$ (mean $55.7m^3/m^2/day$). The range of PACS dosage concentration was 14.0~31.5 mg/L. As the results of operation, the range of removal efficiency of turbidity, SS were 81.0~95.8% (mean 89.5%) 81.8~99.0% (mean 91.4%), respectively. An increase of filtration basin retention time brought on increased of removal efficiency of turbidity and SS, and increase of SOR brought on decreased of removal efficiency. During the first flush in urban area, storm runoff have an high concentration of SS (200~600 mg/L) and the filtration bed becomes clogged and decreased of removal efficiency. Backwashing begins when the drainage pipe valve at the filtration tank bottom is completely open (backwashing stage 1). Backwashing stage 2 was using air bubbles and water jet washing the media for 5 mins and open the drainage valve. After backwashing stage 1, 2, 61.83~64.04%, 18.53~27.51% of SS loading was discharged from filtration tank, respectively. Discharged SS loading from effluent was 7.12~14.79% and the range of residual SS loading in fliter was 2.26~5.00%. The backwashing effects for turbidity, SS were 89.5%, 91.4%, respectively. The hydrocyclone coagulation and filtration with backwashing system, which came out to solve the problems of the costly exchange filter media, and low efficiency of removing micro particles of filter type nonpoint treatment devices, is considered as an alternative system.

• The Journal of Industrial Distribution & Business
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• v.10 no.11
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• pp.49-56
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• 2019

Purpose: Corporate social responsibility is a self-regulating business model that helps a firm be socially accountable to the public. By practicing corporate social responsibility, firms can be conscious of the kind of impact they are having on all aspects of society, including economic, social, and environmental. Corporate social responsibility activities are not directly linked to increasing corporate performance and corporate value, but rather involve spending expenses. Based on these facts, this study verifies whether the effects of corporate social responsibility activities differ depending on the firm's situation. Research design, data and methodology: This study analyzed the effect of market competition on corporate social responsibility activities using logistic regression analysis on listed companies in the KOSPI and KOSDAQ for fiscal years 2014 through 2016. In this study, market competition was measured using the Herfindahl-Herschman Index(HHI). Higher HHI value can be interpreted as a lower degree of market competition. We also measured corporate social responsibility activities using the KEJI Index published by the Korea Economic Justice Institute (KEJI). If a firm-year is included in the top 200 companies of the KEJI Index, it is classified as a good corporate social responsibility activity firm. Results: We find that companies in less competitive market were not included in the KEJI Index. This result indicates that firms in the market with lower market competition perform less corporate social responsibility activities that incur costs. An additional analysis showed that there was a significant negative relationship between the market competition and the corporate social responsibility activity scores published by the KEJI Index. These result adds robustness to the result of the hypothesis that firms that have a monopolistic place in the market practice passive corporate social responsibility activities. Conclusions: The results show that managers of a firm in the lower market competition have a lower incentive to use limited resources for projects that are not directly related to revenue. The results of this study imply that corporate social responsibility activities vary according to the position of the business. Therefore, this study suggests that market investors should consider the degree of competition in the market when they evaluate corporate social responsibility activities.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.42 no.1
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• pp.1-11
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• 2005

Several Solid Freeform Fabrication Systems(SFFS) are commercialized in a few companies for rapid prototyping. However, they have many technical problems including the limitation of applicable materials. A new method of agile prototyping is required for the recent manufacturing environments of multi-item and small quantity production. The objectives of this paper include the development of a novel method of SFFS, the CAFL/sup VM/(Computer Aided Fabrication of Lamination for Various Material), and the manufacture of the various material samples for the certification of the proposed system and the creation of new application areas. For these objectives, the technologies for a highly accurate robot path control, the optimization of support structure, CAD modeling, adaptive slicing was implemented. However, there is an important problem with the conventional 2D lamination method. That is the inaccuracy of 3D model surface, which is caused by the stair-type surface generated in virtue of vertical 2D cutting. In this paper, We design the new control algorithm that guarantees the constant speed, precise positioning and tangential cutting on the 5DOF SFFS. We develop the tangential cutting algorithm to be controlled with constant speed and successfully implemented in the 5DOF CAFL/sup VM/ system developed in this paper. Finally, this paper confirms its high-performance through the experimental results from the application into CAFL/sup VM/ system.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.3
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• pp.169-173
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• 2015

This study is to predict the life exponent by measuring, over 7 years, the insulation resistance of high-voltage cables in 22 kV operation for 13 years. We found out the lifetime index in order to determine the time-dependent trend of deteriorating performance of power cables. The insulation resistances decreased according to elapsed time. We found that: the initial measurements of the cable systems were in agreement with the deterioration properties of the Arrhenius Law. By analyzing the life curve of the cable system, we also verified that the value of the life exponent (n) in the v-t characteristics defined by Weibull distribution has values from 10 to 11. When designing the cable system, the initial value of life exponent was chosen as 9 without any grounding. We have verified that the theoretical grounding based on the design safety of n=9 was actually the best one available. In the short term, we apply our research result to the diagnosis and evaluation of the power cables. In the long run, however, we plan to reduce the cost of the installation and management of cable systems in operation at power stations.

• Journal of the Earthquake Engineering Society of Korea
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• v.6 no.2
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• pp.63-71
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• 2002

This paper examines the ASCE first generation benchmark problem for a seismically excited cable-stayed bridge, and proposes a new semi-active control strategy focusing on inclusion of effects of control-structure interaction. This benchmark problem focuses on a cable-stayed bridge in Cope Girardeau, Missouri, USA, for which construction is expected to be completed in 2003. Seismic considerations were strongly considered in the design of this bridge due to the location of the bridge in the New Madrid seismic zone and its critical role as a principal crossing of the Mississippi River. In this paper, magnetorheological(MR) fluid dampers are proposed as the supplemental damping devices, and a clipped-optimal control algorithm is employed. Several types of dynamic models for MR fluid dampers, such as a Bingham model, a Bouc-Wen model, and a modified Bouc-Wen model, are considered, which are obtained from data based on experimental results for full-scale dampers. Because the MR fluid damper is a controllable energy-dissipation device that cannot add mechanical energy to the structural system, the proposed control strategy is fail-safe in that bounded-input, bounded-output stability of the controlled structure is guaranteed. Numerical simulation results show that the performance of the proposed semi-active control strategy using MR fluid dampers is quite effective.

• Journal of the Earthquake Engineering Society of Korea
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• v.16 no.5
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• pp.41-53
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• 2012

The objective of this study is to evaluate the seismic capacity of RC piers with small aspect ratios. Test specimens were selected from the prototype piers among existing national roadway bridges which are expected to fail in shear and/or complex shear-flexural mode. Two groups of full scale RC pier models were constructed with aspect ratios of 2.25 and 2.67. Quasi-static tests have been implemented to investigate the failure behavior of the RC piers in terms of the lap-spliced longitudinal reinforcing steel and the aspect ratio. It is confirmed that regarding its shear-flexural behavior, the pier is very sensitive to the aspect ratio or details. In the case of a test pier with highly lap-spliced longitudinal bars, the bond failure of lap-splice steels was the dominant cause of failure before the occurrence of flexure or shear-flexural failure, despite a slight change in the aspect ratio. Finally, based on the test results and analysis, this paper proposes formulas for the yielding and ultimate displacements of circular reinforced concrete bridge piers without seismic details. These formulas will be useful for the investigation and upgrade of the seismic capacity of bridge piers without seismic details.

• JSTS:Journal of Semiconductor Technology and Science
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• v.5 no.3
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• pp.149-158
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• 2005

This paper describes design, fabrication, and application of the silicon based temperature controllable micro reactor. In order to achieve fast temperature variation and low energy consumption, reaction chamber of the micro reactor was thermally isolated by etching the highly conductive silicon around the reaction chamber. Compared with the model not having thermally isolated structure, the thermally isolated micro reactor showed enhanced thermal performances such as fast temperature variation and low energy consumption. The performance enhancements of the micro reactor due to etched holes were verified by thermal experiment and numerical analysis. Regarding to 42 percents reduction of the thermal mass achieved by the etched holes, approximately 4 times faster thermal variation and 5 times smaller energy consumption were acquired. The total size of the fabricated micro reactor was $37{\times}30{\times}1mm^{3}$. Microchannel and reaction chamber were formed on the silicon substrate. The openings of channel and chamber were covered by the glass substrate. The Pt electrodes for heater and sensor are fabricated on the backside of silicon substrate below the reaction chamber. The dimension of channel cross section was $200{\times}100{\mu}m^{2}$. The volume of reaction chamber was $4{\mu}l$. The temperature of the micro reactor was controlled and measured simultaneously with NI DAQ PCI-MIO-16E-l board and LabVIEW program. Finally, the fabricated micro reactor and the temperature control system were applied to the thermal denaturation and the trypsin digestion of protein. BSA(bovine serum albumin) was chosen for the test sample. It was successfully shown that BSA was successfully denatured at $75^{\circ}C$ for 1 min and digested by trypsin at $37^{\circ}C$ for 10 min.

• Child Health Nursing Research
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• v.19 no.1
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• pp.1-11
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• 2013

Purpose: This study was done to develop a scenario and evaluate student performance in simulation learning of care for children with respiratory distress syndrome in neonatal intensive care units. Methods: To test the application effect, a one group pre-test design was applied. The scenario based on actual patients and textbook material was developed through several meetings of experts. The scenario was used with 17 groups of 55 senior nursing students who participated voluntarily. Results: Contents were organized focusing on the nursing process for simulation learning. In the application of knowledge and skills, nursing students had high scores in the contents of observation of oxygen saturation, and care to relieve dyspnea. Participants' ability, especially in suction and oxygen supply in the evaluation of objective structured clinical examination was not adequate. There was a significant positive correlation between problem-solving ability and satisfaction in learning. Conclusion: The respiratory distress syndrome simulation scenario developed in this study was an effective tool to give students experience in problem solving and critical thinking ability under conditions similar to reality. The development of various scenarios for child nursing care is needed.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.7
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• pp.1505-1510
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• 2014

High-Pass (ETC ; Electronic Toll Collection) system is one of the basic elements, which adopts a wireless communication method using 5.8 GHz and can realize a part of ITS (Intelligent Traffic System). On the other hand, communication errors occur frequently in Hi-Pass system due to signal erros, multi-path reflection, and/or system-to-system interferences. To solve these problems, an EM (Electro-Magnetic) wave absorber can be used. To solve these Problems, we fabricated some samples in the different composition ratios of Carbon, Sendust, and CPE, and it was confirmed that the optimum composition ratio of Carbon : Sendust : CPE is 10 : 40 : 50 wt.%. The complex relative permittivity and complex relative permeability were derived by using the measured data. In addition, the optimum design parameters for the absorber were determined by simulation. Then the absorption abilities were calculated by changing the thickness of the EM wave absorbers. As a result, the optimum thickness of the developed EM wave absorber was 2.85 mm with absorption ability over 22.4 dB at 5.8 GHz. Futhermore, the EM wave absorber was fabricated based on the simulated and designed values. The measured values agreed well with the simulated ones. Therefore, it was clearly shown that the developed EM wave absorber in this paper is to be applied in actual situations.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.7C
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• pp.647-657
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• 2005

In this paper, we proposed a new lifting architecture for JPEG2000 and implemented to ASIC. We proposed a new cell to execute unit calculation of lifting using the property of lifting which is the repetitious arithmetic with same structure, and then recomposed the whole lifting by expanding it. After the operational sequence of lifting arithmetic was analyzed in detail and the causality was imposed for implementation to hardware, the unit cell was optimized. A new lifting kernel was organized by expanding simply the unit cell, and a lifting processor was implemented for Motion JPEG2000 using it. The implemented lifting kernel can accommodate the tile size of 1024$\times$1024, and support both lossy compression using the (9,7) filter and lossless compression using (5,3) filter. Also, it has the same output rate as input rate, and can continuously output the wavelet coefficients of 4 types(LL, LH, HL, HH) at the same time. The implemented lifting processor completed a course of ASIC using 0.35$\mu$m CMOS library of SAMSUNG. It occupied about 90,000 gates, and stably operated in about 150MHz though difference from the used macro cell for the multiplier. Finally, the improved operated in about 150MHz though difference from the used macro cell for the multiplier. Finally, the performance can be identified in comparison with the previous researches and commercial IPs.