• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.12
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• pp.1145-1151
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• 2007

In this paper, vibration sources of an electric forklift are identified and the forklift vibrations are reduced by structural modification. For vibration identification, vibration signals are measured by an accelerometer when the forklift is moving. These signals are presented in a waterfall plot in order to find the dependency of frequency components on the forklift speed. It is found that main vibration source is tire pattern excitation. From some experiments and finite element analyses, it is also found that resonances occur because the natural frequencies of the forklift exist in usual driving speed range. To shift the natural frequencies outside the driving speed range, the connection parts between main body and loader are modified to increase stiffness. It is verified that considerable amount of vibration are reduced by the structural modification.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.5 s.110
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• pp.470-478
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• 2006

An efficient method for change of eigenvectors and eigenvalues due to the modifying proportional damping structure using sensitivity coefficients is presented. Sensitivity coefficients are determined by iteration with eigenvalue and eigenvectors before modification of system. The proposed method is applied to examples of 3 degrees of freedom system and plate by modifying mass and stiffness. The predicted change of eigenvectors and eigenvalues are in a good agreement with these from the structural re-analysis after modification of mass and stiffness.

• Journal of the Korean Society for Heat Treatment
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• v.13 no.3
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• pp.170-176
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• 2000

A novel method for improving the adhesion of diamond films on cemented carbide tool inserts has been investigated. This method is based on the formation of a compositionally graded interface by developing a microrough surface structure using a pulsed laser process. Residual stresses of diamond films deposited on laser modified cemented carbides were measured as a function of substrate roughness using micro-Raman spectroscopy. The surface morphology and roughness of diamond films and cemented carbides were also investigated at different laser modification conditions. It was found that the increasing interface roughness reduced the average residual stress of diamond films, resulting in improved adhesion of diamond films on cemented carbides.

• Bulletin of the Korean Chemical Society
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• v.34 no.11
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• pp.3295-3300
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• 2013

Acrolein (ACR) is a well-known carbonyl toxin produced by lipid peroxidation of polyunsaturated fatty acids, which is involved in the pathogenesis of neurodegenerative disorders such as Alzheimer's disease (AD). In Alzheimer's brain, ACR was found to be elevated in hippocampus and temporal cortex where oxidative stress is high. In this study, we evaluated oxidative modification of cytochrome c occurring after incubation with ACR. When cytochrome c was incubated with ACR, protein aggregation increased in a dose-dependent manner. The formation of carbonyl compounds and the release of iron were obtained in ACR-treated cytochrome c. Reactive oxygen species scavengers and iron specific chelator inhibited the ACR-mediated cytochrome c modification and carbonyl compound formation. Our data demonstrate that oxidative damage of cytochrome c by ACR might induce disruption of cyotochrome c structure and iron mishandling as a contributing factor to the pathology of AD.

• Bulletin of the Korean Chemical Society
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• v.34 no.2
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• pp.406-410
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• 2013

Tetrahyropapaveroline (THP) is compound derived from dopamine metabolism and is capable of causing dopaminergic neurodegenerative disorder, such as Parkinson's disease (PD). The aim of this study was to evaluate the potential of THP to cause oxidative damage on the structure of cytochrome c (cyt c). Our data showed that THP led to protein aggregation and the formation of carbonyl compound in protein aggregates. THP also induced the release of iron from cyt c. Reactive oxygen species (ROS) scavengers and iron specific chelator inhibited the THP-mediated cyt c modification and carbonyl compound formation. The results of this study show that ROS may play a critical role in THP-induced cyt c modification and iron releasing of cyt c. When cyt c that has been exposed to THP was subsequently analyzed by amino acid analysis, lysine, histidine and methionine residues were particularly sensitive. It is suggested that oxidative damage of cyt c by THP might induce the increase of iron content in cells and subsequently led to the deleterious condition. This mechanism is associated with the deterioration of organs under neurodegenerative disorder such as PD.

• Structural Engineering and Mechanics
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• v.33 no.3
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• pp.261-284
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• 2009

The seismic behavior of a framed structure with chevron-type buckling restrained braces was investigated and their behavior factors, such as overstrength, ductility, and response modification factors, were evaluated. Two types of structures, building frame systems and dual systems, with 4, 8, 12, and 16 stories were designed per the IBC 2003, the AISC LRFD and the AISC Seismic Provisions. Nonlinear static pushover analyses using two different loading patterns and incremental dynamic analysis using 20 earthquake records were carried out to compute behavior factors. Time history analyses were also conducted with another 20 earthquakes to obtain dynamic responses. According to the analysis results, the response modification factors turned out to be larger than what is proposed in the provision in low-rise structures, and a little smaller than the code-values in the medium-rise structures. The dual systems, even though designed with smaller seismic load, showed superior static and dynamic performances.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.12
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• pp.3782-3791
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• 1996

A great deal of effert has been invested in upgrading the performance and the efficiency of mechanical structures. Using experimental modal analysis(EMA) or finite element analysis(FEA) data of mechanical structures, this performance and efficiency can be effectively evaluated. In order to analyze complex structures such as automobiles and aircraft, for the sake of computing efficiency, the dynamic substructuring techniques that allow to predict the dynamic behavior of a structure based on that of the composing structures, are widely used. By llinking a modal model obtained from EMA and an analytical model obtained from FEA, the best conditioned structures can be desinged. In this paper, a new algorithm for structural dynamic modification-SRFSM (substructure response function sensitivity method) is proposed by linking frequency responce function synthesis and response function sensitivity. A mehtod to obtain response function sensitivity using direct derivative of mechanical impedance, is also used.

• Journal of Aerospace System Engineering
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• v.15 no.5
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• pp.106-112
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• 2021

In this study, we performed a design and structural analysis of a blade-shaped antenna installation on the rear fuselage of a rotary wing aircraft operated by the military. When the structure is damaged while the aircraft is in operation, it is separated from the aircraft main structure and may collide with the rotor or blades to cause the aircraft to crash. Therefore, structural safety for the modified structure must be secured. The design requirement for the newly installed modified part were established, and the load condition was constructed by applying the load that may occur in the aircraft after the modification. Structure safety for the modified structure was secured by performing structure analysis. To analysis stress and deformation of aircraft structure, we developed finite element model and verified it by using hand calculation method. We confirmed the safety of the modified structure through the final structural integrity analysis.

• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.601-604
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• 2002

We propose modified fence electrode structure for manufacturing of ITO-electrode-free PDP. Luminance, luminance efficiency and addressing time for the proposed structure shows performance improvement about 25 percent. Our results can be used for the reduction of manufacturing cost without degradation of PDP performance.

• Proceedings of the IEEK Conference
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• 2002.06a
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• pp.383-386
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• 2002

The goal of this study is to realize the PBG lowpass filter using novel PBG structure modification both upper layer and ground layer. It has been designed three aperture slots of ground layer for PBG structure which the center slot shape of ground is two type, rectangular and dumbbell. This PBG LPF llas the character of the broader stopband and smaller size than typical LPF. The measurement results have matched the simulated ones. It has the cutoff frequency of each 4.4650Hz and 3.520Hz and at least -2OdB of the signal suppression at the stopband.