• Journal of Environmental Science International
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• v.20 no.12
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• pp.1509-1519
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• 2011

The protective effect of nitric oxide (NO) on the antioxidant system under paraquat(PQ) stress was investigated in leaves of 8-week-old lettuce (Lactuca sativa L.) plants. PQ stress caused a decrease of leaf growth including leaf length, width and weight. Application of NO donor, sodium nitroprusside (SNP), significantly alleviated PQ stress induced growth suppression. SNP permitted the survival of more green leaf tissue preventing chlorophyll content reduction and of higher quantum yield for photosystem II than in non-treated controls under PQ exposure, suggesting that NO has protective effect on chloroplast membrane in lettuce leaves. Flavonoids and anthocyanin were significantly accumulated in the leaves upon PQ exposure. However, the rapid increase of these compounds was alleviated in the SNP treated leaves. PQ treatment resulted in lipid peroxidation and induced accumulation of hydrogen peroxide ($H_2O_2$) in the leaves, while SNP prevented PQ induced increase in malondialdehyde (MDA) and $H_2O_2$. These results demonstrate that SNP serves as an antioxidant agent able to scavenge $H_2O_2$ to protect plant cells from oxidative damage. The activities of two antioxidant enzymes that scavenge reactive oxygen species, superoxide dismutase (SOD) and catalase (CAT) in lettuce leaves in the presence of NO donor under PQ stress were higher than those under PQ stress alone. Application of 2-(4-carboxyphenyl)-4, 4, 5, 5-tetramethylimidazoline-1-oxyl-3-oxide (PTIO), a specific NO scavenger, to the lettuce leaves arrested SNP mediated protective effect on leaf growth, photosynthetic pigment and antioxidant systems. However, PTIO had little effect on lettuce leaves under PQ stress compared with that of PQ stress alone. The obtained data suggest that the damage caused by PQ stress is in part due to increased generation of active oxygen by maintaining increased antioxidant enzyme activities and SNP protects plants from oxidative stress. From these results it is suggested that NO might act as a signal in activating active oxygen scavenging system that protects plants from oxidative damage induced by PQ stress and thus confer PQ tolerance.

• Korean Journal of Construction Engineering and Management
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• v.9 no.4
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• pp.140-153
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• 2008

The recent stagnation of construction market draw more attention to construction technology development which is believed to be playing a important role in increasing the competitiveness of the construction industry. Thus, increasing pressures has been on the government playing a catalytic role of strengthen technology competitiveness. Hereupon, this study analyzed technology skill evaluation items of the Pre-Qualification system to facilitate construction technology development at the national level and tried to show the correlation between the PQ system and patent application through multilateral analysis of patent applications. Analysis results are intended to provide basic reference in decision-making process related to governmental regulation improvement especially on the PQ system. This research also attempted to draw implications to increase the use of technology related regulations such as patent & utility model based on PQ system analysis results. To do so, a comprehensive trend Analysis on the PQ system has been conducted from the view points of construction technology. Similar analysis has been done with the patent system & Utility model system. Based on Analysis result, implications of regulation improvements was outlined to promote construction technology development, due to eventually increase the competitiveness of Korean construction industry.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.13 no.12
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• pp.965-971
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• 2003

To reach high areal density, less track pitch is expected and more servo bandwidth is required. One approach to overcoming the problem is by using dual stage servo system. For this system. we have suggested new milliactuator based on the shear mode of piezoelectric elements to drive the head suspension assembly. In this paper, we introduce milliactuator and controller design method, PQ method. PQ method reduces the controller design problem for DISO (dual-input/single-output) systems to two standard controller design problems for SISO ( single-input/single-output) problems. The first part of PQ method directly addresses the issue of actuator output contribution, and the second part allows the use of traditional loop shaping to achieve the overall system performance. This paper shows how to employ the PQ method to meet aggressive close-loop performance specifications for a disk drive system with a VCM and piezoelectric milliactuator.

• KIEE International Transactions on Power Engineering
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• v.4A no.4
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• pp.214-220
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• 2004

Power quality monitoring is the cornerstone for power quality analysis, diagnosis and improvement. The measurement of power quality (PQ) evolves from instantaneous metering to continuous monitoring. Furthermore, recent technologies enable us to construct more flexible, reliable, rapid and economical power quality monitoring system (PQMS). Therefore, this paper presents an improved PQMS with a new distributed monitoring structure. The proposed PQMS consists of a PQ meter, PQ analyzer and GUI. The PQ meter only collects raw data and the PQ analyzer performs power quality analysis. It has several advantages compared to conventional structures in economic efficiency, modularity, speed, etc. PQ monitoring algorithms to catch steady-state trends and to detect PQ events are also adapted to the proposed structure. Using the proposed structure and monitoring algorithm, a prototype PQMS is constructed and real-time testing is performed.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.67 no.4
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• pp.191-199
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• 2018

The harmonic reduction method of ac motor drive, ACL and DCL were commonly used, but the current distortion ratio was only 35%, thus the several different types of filters as BBHF(broad band harmonic filter), HHF(hybrid harmonic filter), NHHF(new hybrid harmonic filter) have been developed to satisfy the IEEE Std. 519 harmonic limitation. However, these filters had been limited marketability due to cost and size problems. This study suggests the methods to reduce cost and size of the harmonic filter including topologies, besides we discussed simulation results of the power system with regard to the implementation and performance of the filters.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.9
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• pp.86-93
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• 2011

The necessity of Power Quality(PQ) Management grow bigger because the disturbance strength in power system is increasing, on the other hand, the tolerance of electrical components is reducing with widely use of the IT and digital equipments. The domestic management standards on power quality are enacted based on the IEC standards in recent. Since the IEC standards defines the measurement and evaluation point on PQ as PCC(Point of Common Coupling) which is normally the point of penetration between customer and power company, the PQ monitoring system(PQMS) should be made to measure and manage the PQ of custom effectively. In this paper, therefore, the economical construction plan on PQMS using the wireless communication channel in distribution automation system is suggested, and the usefulness of the PQMS are shown by analyzing the PQM data with IEC standards.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.29B no.10
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• pp.10-18
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• 1992

This paper considers and implementation of the memory system which provides simultaneous access to pq image points of block(p$\times$q), horizontal vector(1$\times$pq)and/vertical vector(pq$\times$1) in 2-dimension image array, where p and q are design parameters. This memory system consists of an address calculation circuit, address routing circuit, data routing circuit, module selection circuit and m memory modules where m>qp. The address calculation circuit computes pq addresses in parallel by using the difference of addresses among image points. Extra module assignment circuit is not used by improving module selection circuit with routhing circuit. By using Verilog-XL logic simulator, we verify the correctness of the memory system and estimate the performance. The implemented system provides simultaneous access to 16 image points and is 6 times faster than conventional memory system.

• The Transactions of the Korean Institute of Power Electronics
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• v.8 no.6
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• pp.527-533
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• 2003

Recently, need of power stability and reliability has been increased as the spread of the sensitive electronic loads. Therefore, the power quality(PQ) problems become the hot Issue of public interest in these days. Many kinds of algorithms have been studied for the monitoring of PQ problems using the monitoring algorithms with RMS or FFT scheme, but it is still not enough to measure all of the PQ problems. This paper proposed the application of discrete wavelet transform(WT) for the PQ problems monitoring with the Introduction of WT theory, and the design of PQ monitoring data acquisition system Is described with some experimental results to verify the validity of the proposed PQ monitoring algorithm.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11a
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• pp.46-51
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• 2001

To reach high areal density, less track pitch is expected and more servo bandwidth is required. One approach to overcoming the problem is by using dual stage servo system. In this system, a voice coil motor (VCM) is used as the primary stage while a milliactuator is used as the secondary stage. We have suggested new milliactuator based on the shear mode of piezoelectric elements to drive the head suspension assembly. In this paper, we introduce controller design method, PQ method. PQ method reduces the controller design problem for DISO(dual-input/single-output) systems to two standard controller design problems for SISO(single-input/single-output) problems. The first part of PQ method directly address the issue of actuator output contribution, and the second part allows the use of traditional loop shaping to achieve the overall system performance. This paper shows how to employ the PQ method to meet aggressive close-loop performance specifications for a disk drive system with a VCM and piezoelectric milliactuator.

• Biomolecules & Therapeutics
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• v.23 no.5
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• pp.407-413
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• 2015

Paraquat dichloride (N,N-dimethyl-4-4'-bipiridinium, PQ) is an extremely toxic chemical that is widely used in herbicides. PQ generates reactive oxygen species (ROS) and causes multiple organ failure. In particular, PQ has been reported to be an immunotoxic agrochemical compound. PQ was shown to decrease the number of macrophages in rats and suppress monocyte phagocytic activity in mice. However, the effect of PQ on macrophage cell viability remains unclear. In this study, we evaluated the cytotoxic effect of PQ on the mouse macrophage cell line, RAW264.7 and its possible mechanism of action. RAW264.7 cells were treated with PQ (0, 75, and $150{\mu}M$), and cellular apoptosis, mitochondrial membrane potential (MMP), and intracellular ROS levels were determined. Morphological changes to the cell nucleus and cellular apoptosis were also evaluated by DAPI and Annexin V staining, respectively. In this study, PQ induced apoptotic cell death by dose-dependently decreasing MMP. Additionally, PQ increased the cleaved form of caspase-3, an apoptotic marker. In conclusion, PQ induces apoptosis in RAW264.7 cells through a ROS-mediated mitochondrial pathway. Thus, our study improves our knowledge of PQ-induced toxicity, and may give us a greater understanding of how PQ affects the immune system.