• Journal of the Computational Structural Engineering Institute of Korea
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• v.16 no.2
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• pp.183-195
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• 2003

In this study, the method of the finite element modeling for free vibration control of beam-type smart structures with bonded plate-type piezoelectric sensors and actuators is proposed. Constitutive equations for the direct piezoelectric effect and converse piezoelectric effect of piezoelectric materials are considered. By using the variational principle, the equations of motion for the smart beam finite element are derived. The proposed 2-node beam finite element is an isoparametric element based on Timoshenko beam theory. Therefore, by analyzing beam-type smart structures with smart beam finite elements, it is possible to simulate the control of the structural behavior by applying voltages to piezoelectric actuators and monitoring of the structural behavior by sensing voltages of piezoelectric sensors. By using the smart beam finite element and constant-gain feed back control scheme, the formulation of the free nitration control for the beam structures with bonded plate-tyPe Piezoelectric sensors and actuators is proposed.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.3
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• pp.371-377
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• 2007

In this paper, acceleration threshold of perception for the horizontal vibration of tall buildings was estimated. Excessive vibration of tall buildings by wind can give displeasure, such as giddiness and visual insecurity. To provide comfortable environment to residents of tall buildings, acceleration needs to be limited. For tall buildings the first mode of vibration is dominant. To reproduce the first mode of vibration, experiments were performed by generating sine waves by a shaking table. A nitration house was made and forty persons were employed for experiments. The forty persons were organized into five experimental groups, each of which was composed of eight persons, and the threshold of perception for horizontal vibration was measured by increasing acceleration in the range of 0.2Hz through 1.2Hz of frequency, Performance curves were obtained by dividing the distribution of perception for horizontal vibration into the range of $0{\sim}20%,\;21{\sim}40%,\;41{\sim}60%,\;61{\sim}80%\;and\;81{\sim}100%$ and by fitting curves.

• Analytical Science and Technology
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• v.28 no.6
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• pp.430-435
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• 2015

Two-dimensional analysis between the explosive performance and the impact sensitivity for methylnitroimidazole derivatives was performed to understand where these new energetic molecules could be utilized. The explosive performance was analyzed with the Cheetah program, while the impact sensitivity was predicted using neural network analysis. Successive nitration of methylimidazole made the molecule more sensitive, but methyltrinitroimidzole appeared to have a relatively good safety characteristic. We recently developed a novel method to analyze the potential usage of new energetic molecules using a two-dimensional chart, where the explosive performance and the impact sensitivity were located on the X-axis and Y-axis, respectively. An analysis of a two-dimensional plot between the performance and the sensitivity indicated that methyldinitroimidazole would be useful for insensitive explosive formulations, while methyltrinitroimidazole was forecasted for use as an ingredient for high explosive formulations.

• Journal of the Korean Ceramic Society
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• v.29 no.7
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• pp.511-516
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• 1992

In this study, SiC powder and Si powder were used as the raw materials. Mixture was prepared with addition of Al2O3 and Fe2O3 at 0.1~0.5wt% respectively. After this step, the mixture was pressed and nitrided for 30 hrs at 140$0^{\circ}C$ under NH3-N2 atmosphere. Mechanical properties of sintered specimens were investigated from measurement of porosity, bulk density and three point bending test. nitration reaction extent was observed at the change of mass before and after reaction, and the microstructure and the change of $\alpha$-Si3N4 and $\beta$-Si3N4 were observed by XRD and SEM. In the current work, the results are as follows 1. When Fe2O3 added, the nitridation increased with the content of Fe2O3, and the bending strength was increased from 0.1 wt% to 0.3 wt%, and decreased to 0.5 wt%. 2. When Al2O3 added, the nitridation and the bending strength increased little by little with the content of Al2O3 3. The bending strength of the specimen added with Fe2O3 were higher than that with Al2O3. Because the specimens contained Fe2O3 had much more the whisker type crystal of Si3N4 contributing to strength than contained Al2O3.

• Asian Journal of Atmospheric Environment
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• v.4 no.1
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• pp.1-8
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• 2010

The effectiveness of the government regulation on tail-pipe emission for diesel vehicles issued in 2003 in Tokyo was evaluated in this study. Variations in annual average concentrations of polycyclic aromatic hydrocarbons (PAHs) and nitro-PAHs associated with airborne particulate matter were investigated in connection with the variation in airborne elemental carbon (EC) concentration in downtown Tokyo, Japan in 2006-2007 and in 1997-1998. The annual average concentrations of EC, seven different PAHs, and 1-nitropyrene were found to have decreased significantly from 1997-1998 to 2006-2007. The most prominent decrease in atmospheric concentration was observed for 1-nitropyrene, which is a representative nitro-PAH originating from diesel vehicles. This indicated that the government control has worked to considerably reduce both atmospheric mutagens and airborne particulate matter. In contrast, the concentrations of two nitro-PAHs, 2-nitrofluoranthene and 2-nitropyrene, remained the same. These nitro-PAHs are known to be formed by atmospheric nitration of their parent PAHs, and this result suggested factors other than the concentration of parent PAHs and $NO_2$ affects the degree of atmospheric formation of nitro-PAHs.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.5
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• pp.555-559
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• 2011

Oil hydraulic piston pumps are extensively used worldwide because of their simple design, light weight, and cost effectiveness. However, an oil hydraulic pump is likely to have high leakage, friction, and low energy efficiency after long-term use. In oil hydraulic piston pumps the clearance between the valve block and the piston plays an important role in the volumetric and overall efficiency. We studied the wear property of the SACM645 material used in hydraulic piston pumps via experiments with different heat treatments. We prepared three different specimens. The maximum tensile strengths of the QT and QT-nitration specimens are similar (about 820 MPa), but the strains are significantly different. However, the fatigue characteristic depended on the heat treatment.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.2
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• pp.164-171
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• 2004

Active control techniques have been used in wide areas of noise and nitration control engineering and a noise barrier is one of them. Omoto's work in 1993 would be one of the fundamental and systematic studies on the actively controlled noise barrier, in which he used equal number of control sources and error sensors. The error sensors were placed uniformly along the top edge of the noise barrier with equal distance apart and the control sources were placed in the exactly same way some distance apart from the error sensors. Since then, a couple of studies were made on the secondary sources'arrangement rather than the optimality of secondary source positions. Shao's results showed that arc shaped arrangement for secondary sources is better than the straight line one, and later work of Yang showed that the more important factor is the average distance between the primary source and secondary sources. However, since these studies were all executed with a simple uniform distribution of the secondary sources along the straight line or arc, it is difficult to conclude which arrangement is superior In order for the fare comparison. the optimality of the source positions in each arrangement must be given in prior. The primary goal of this study is focused on this aspect and some major factors were investigated and compared. The computer simulation results showed that the arc shaped arrangement is marginally better than the straight line one, and more importantly slightly tuned position can greatly improve the performance of the control system.

• KSBB Journal
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• v.19 no.1
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• pp.57-61
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• 2004

A peroxynitrite is formed when superoxide and nitric oxide exist at near eqimolar ratio in biological systems. Although not a free radical by chemical nature, peroxynitrite is a powerful oxidant having a wide array of tissue damaging effects ranging from lipid oxidation and inactivation of enzymes and ion channels through protein oxidation and nitration to inhibition of mitochondrial respiration. During our search for new antioxidizing components from natural resources, twenty salt marsh plants were screened for their ONOO and DPPH radical scavenging activities. Among them, methanol extract of Rosa rugosa, lxeris tamagawaensis, Erigeron annus, Tetragonia tetragonoides, Imperata cylindrica, and Suaeda japonica inhibited more than 85% of peroxynitrite produced by 3-morpholinsydnonimine (SIN-1) at a concentration of 5 $\mu\textrm{g}$/$m\ell$. In addition, Rosa rugosa, Artemisia capillaris, Erigeron annus and Ixeris tamagawaensis showed significant scavenging effect against DPPH (1,1-diphenyl-2-picrylhydrazyl radical).

• Journal of the Korean institute of surface engineering
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• v.31 no.1
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• pp.54-62
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• 1998

In this study, the behaviorof ion nitriding of AISI 304 stainless steel was investigated using plasma ion nitriding system. The characteristics of ion nitriding, and their micsoctrucyures, and physical properties were investigated as a function of process parmeteds. important conclusions can be summarzied as follows. Firstly, it was found that growth of nitride layer in ion nitriding are mainly affected by N2 partial pressures and nitriding temperatures for AISI 304 stainless steel. The $N_2$<\TEX> partial pressure plays on important role in ion nitriding since it determiness the incoming flux of nitrogen species onto specimen surface. Nitriding thmprrature is also important besauseit determines the diffusion rates of nitrogen through nitride layers. While both parameters affects the characteristics rateding are controlled by nitridingen diffusion nitration profiles of N and alloying elements such as Cr and Ni are observed through niride layers. Secondly, nitride layer consists of the upper white laywe having various nitride phases and the underneath diffusion layers. The thickness of white layer increases with $N_2$<\TEX> partial pressures and nitriding temperatures. The thinkness of diffusion layer is increasting nitriding temperatures. Finally, nitriding of stainless steels steel show slighly low their corrsionce prorerties. However, passivation properties, which is normally observed in stainless steels, were still observed aftre ion nitriding.

• Journal of Plant Biotechnology
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• v.34 no.4
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• pp.355-361
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• 2007

Cotyledons of perilla6 were cultured on MS medium containing 0.5 mg/l NAA and 0.5 mg/l BA for 7 weeks. The activity of perilla peroxidase was observed to increase following culture stages as assessed by peroxidase assay. A peroxidase (POD) was purified from perilla tissue cultured on MS medium for 7 weeks. The peroxidase was purified using ion exchange and gel nitration chromatography. The perilla peroxidase had a molecular mass of 30 kDa by SDS-PAGE. We showed that the N-terminal amino acid sequence of this protein shared 67% identity with the tea peroxidase. As indicated by SDS-PAGE, the banding pattern of the 30 kDa polypeptide present in total soluble protein from perilla tissue was increased following culture stages. Immunoblot analysis indicated that perilla peroxidase protein appeared after 3 weeks of perilla tissue culture, and continued to increase with extended duration of tissue culture for at least 7 weeks.