• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.44 no.1
• /
• pp.1-7
• /
• 2007

An MTJ element not only computes Boolean function but also stores the output result in itself. We can make the most use of magneto-logic's merits by employing the magneto-logic in substitution for the sequential logic as well as the combinational logic. This unique feature opens a new horizon for potential application of MTJ as a universal logic element. Magneto-logic circuits using MTJ elements are more integrative and non-volatile. This paper presents novel 3-bit magneto-logic up/down counters and presents simulation results based on the HSPICE macro-model of MTJ that we have developed.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2003.06a
• /
• pp.768-771
• /
• 2003

The impulse between launch vehicle and atmosphere can generate a lot of noise and vibration during the process of launching a satellite. Structurally, electronic equipment (KOMPSAT 2, RDU : Remote Drive Unit) of a satellite consists of aluminum case containing PCB (Printed circuit boards). Each PCB has resistors and IC (Integrated circuits). Noise and vibration of wide frequency band are transferred to the inside of fairing, subsequently creating vibration of the electronic equipment of the satellite. In this situation. random vibration can cause malfunctioning of the electronic equipment of the device. Furthermore, when tile frequency of random vibration meets with natural frequency of PCB. fatigue fracture nay occur in the part of solder joint. The launching environment, thus. needs to be carefully considered when designing the electronic equipment of a satellite. In general. the safety of the electronic equipment is supposed to be related to the natural frequency, shapes of mode and dynamic deflection of PCB in the electronic equipment. Structural vibration analysis of PCB and its electronic components can be performed using either FEM(Finite Element Method) or vibration test. In this study. the natural frequency and dynamic deflection of PCB are measured by FEM, aud the safety of the electronic components of PCB is being evaluated according to the results. This study presents a unique method for finite element modeling and analysis of PCB and its electronic components. The results of FEA are verified by vibration test. The method proposed herein may be applicable to various designs from the electronic equipments of a satellite to home electronics.

• The Journal of the Acoustical Society of Korea
• /
• v.14 no.2E
• /
• pp.73-86
• /
• 1995

The transducer section of the forward-looking ultrasound imaging catheter (FLUIC) consists of a circular piezoelectric element as a vibrator and a conical acoustic mirror as a perfect reflector. A small diameter piezoelectric transducer element is mounted on the side of a catheter's rotating shaft. The unique design of FLUIC provides the capability to form a two-dimensional image of a cross-section of vessel in front of the catheter, which is lacking in the present generation of intravascular ultrasound (IVUS) transducers, as well as a conventional side view image. The mirror configuration for the transducer section of the FLUIC is designed using an approximated ray tracing techniques. The diffraction transfer function approach [1] developed for the field prediction from primary sources is generalized and extended to predict the secondary diffraction characterstics from an acoustic mirror. The extended model is verified by simulation and experiment through a simple plane reflector and employed to analyzed the field characteristics of a FLUIC.

• Korean Journal of Materials Research
• /
• v.20 no.1
• /
• pp.31-36
• /
• 2010

Methylene blue (MB) was degraded by $TiO_2$ and ZnO deposited on an activated carbon fiber (ACF) surface under UV light. The ACF/$TiO_2$ and ACF/ZnO composites were characterized by BET, SEM, XRD, and EDX. The BET surface area was related to the adsorption capacity for composites. The SEM results showed that titanium dioxide and zinc oxide are distributed on the ACF surface. The XRD results showed that the ACF/$TiO_2$ and ACF/ZnO composites contained a unique anatase structure for $TiO_2$ and a typical hexagonal phase for ZnO respectively. These EDX spectra showed the presence of peaks of Ti element on ACF/$TiO_2$ composite and peaks of Zn element on the ACF/ZnO composite. The blank experiments for either illuminating the MB solution or the suspension containing ACF/$TiO_2$ or ACF/ZnO in the dark showed that both illumination and the catalyst were necessary for the mineralization of organic dye. Additionally, the ACF/$TiO_2$ composites proved to be efficient photocatalysts due to degradation of MB at higher reaction rates. The addition of an oxidant $([NH_4]_2S_2O_8)$ led to an increase of the degradation rate of MB for ACF/$TiO_2$ and ACF/ZnO composites.

• Journal of Ginseng Research
• /
• v.44 no.1
• /
• pp.96-104
• /
• 2020

Objectives: Oleanolic acid, a minor element of ginsenosides, and its derivatives have been shown to have cytotoxicity against some tumor cells. The impact of cytotoxic effect of oleanolic acid 3-acetate on ovarian cancer SKOV3 cells and endometrial cancer HEC-1A cells were examined both in vivo and in vitro to explore the underlying mechanisms. Methods: Cytotoxic effects of oleanolic acid 3-acetate were assessed by cell viability, phosphatidylserine exposure on the cell surface, mitochondrial release of cytochrome C, nuclear translocation of apoptosis-inducing factor, depolarization of mitochondrial transmembrane potential (∆Ψ_m), and generation of reactive oxygen species (ROS). In vivo inhibition of tumor growth was also assessed with xenografts in immunocompromised mice. Results: Oleanolic acid 3-acetate exhibited potent cytotoxicity toward SKOV3 and HEC-1A cells by decreasing cell viability in a concentration-dependent manner. Importantly, oleanolic acid 3-acetate effectively suppressed the growth of SKOV3 cell tumor xenografts in immunocompromised mice. Furthermore, oleanolic acid 3-acetate induced apoptotic cell death as revealed by loss of ∆Ψ_m, release of cytochrome c, and nuclear translocation of apoptosis-inducing factor with a concomitant activation of many proapoptotic cellular components including poly(ADP-ribose) polymerase, Bcl-2, and caspases-8, caspase-3, and caspase-7. Oleanolic acid 3-acetate, however, caused a decrease in ROS production, suggesting the involvement of an ROS-independent pathway in oleanolic acid 3-acetate-induced apoptosis in SKOV3 and HEC-1A cells. Conclusion: These findings support the notion that oleanolic acid 3-acetate could be used as a potent anticancer supplementary agent against ovarian and endometrial cancer. Oleanolic acid 3-acetate exerts its proapoptotic effects through a rather unique molecular mechanism that involves an unconventional ROS-independent but mitochondria-mediated pathway.

• The Journal of Korean Academy of Prosthodontics
• /
• v.30 no.4
• /
• pp.582-610
• /
• 1992

The long-term success of any dental implant is dependent upon the optimization of stresses which occur during oral function and parafunction. Especially, it has been suggested that there is an unique set of problems associated with joining an osseointegrated implant and a natural tooth with a fixed partial denture. For this particular case, although many literatures suggest different ways to avoid high stress concentrations on the bone surrounding the implant under static and dynamic loading conditions, but few studies on the biomechanical efficacy of each assertion have been reported. The purpose of this investigation was to evaluate the efficacies of clinically suggested methods on stress distribution under static load and shock absorption under dynamic load, using two dimensional finite element method. In FEM models of osseointegrated implant-natural tooth supported fixed partial dentures, calculations were made on the stresses in surrounding bone and on the deflections of abutments and superstructure, first, to compare the difference in stress distribution effects under static load by the flexure of fastening screw or prosthesis, or intramobile connector, and second, to compare the difference in the shock absorption effects under dynamic load by intramobile connector or occlusal veneering with composite resin. The results of this analysis suggest that : 1. Under static load condition, using an implant design with fastenign screw connecting implant abutment and prosthesis or increasing the flexibility of fastening screw, or increasing the flexibility of prosthesis led to the .increase in height of peak stresses in cortical bone surrounding the implant, and has little effect on stress change in bone around the natural tooth. 2. Under static load condition, intramobile connector caused the substantial decrease in stress concentration in cortical bone surrounding the implant and the slight increase in stress in bone around the natural tooth. 3. Under dynamic load condition, both intramobile connector and composite resin veneering showed shock absorption effect on bone surrounding the implant and composite resin veneering had a greater shock absorption effect than intramobile connector.

• Smart Structures and Systems
• /
• v.24 no.3
• /
• pp.303-317
• /
• 2019

Magneto-rheological fluid (MRF) rotatory dampers are normally used for controlling the constant rotation of machines and engines. In this research, such a device is proposed to act as variable stiffness device to alleviate the rotational oscillation existing in the many engineering applications, such as motor. Under such thought, the main purpose of this work is to characterize the nonlinear torque-angular displacement/angular velocity responses of an MRF based variable stiffness device in oscillatory motion. A rotational hysteresis model, consisting of a rotatory spring, a rotatory viscous damping element and an error function-based hysteresis element, is proposed, which is capable of describing the unique dynamical characteristics of this smart device. To estimate the optimal model parameters, a modified whale optimization algorithm (MWOA) is employed on the captured experimental data of torque, angular displacement and angular velocity under various excitation conditions. In MWOA, a nonlinear algorithm parameter updating mechanism is adopted to replace the traditional linear one, enhancing the global search ability initially and the local search ability at the later stage of the algorithm evolution. Additionally, the immune operation is introduced in the whale individual selection, improving the identification accuracy of solution. Finally, the dynamic testing results are used to validate the performance of the proposed model and the effectiveness of the proposed optimization algorithm.

• Structural Engineering and Mechanics
• /
• v.78 no.2
• /
• pp.163-174
• /
• 2021

Track-bridge interaction has become an essential part in the design of bridges and rails in terms of modern railways. As a unique ballastless slab track, the longitudinal continuous slab track (LCST) or referred to as the China railway track system Type-II (CRTS II) slab track, demonstrates a complex force mechanism. Therefore, a comprehensive track-bridge interaction study between multi-span simply supported beam bridges and the LCST is presented in this work. In specific, we have developed an integrated finite element model to investigate the overall interaction effects of the LCST-bridge system subjected to the actions of temperature changes, traffic loads, and braking forces. In that place, the deformation patterns of the track and bridge, and the distributions of longitudinal forces and the interfacial shear stress are studied. Our results show that the additional rail stress has been reduced under various loads and the rail's deformation has become much smoother after the transition of the two continuous structural layers of the LCST. However, the influence of the temperature difference of bridges is significant and cannot be ignored as this action can bend the bridge like the traffic load. The uniform temperature change causes the tensile stress of the concrete track structure and further induce cracks in them. Additionally, the influences of the friction coefficient of the sliding layer and the interfacial bond characteristics on the LCST's performance are discussed. The systematic study presented in this work may have some potential impacts on the understanding of the overall mechanical behavior of the LCST-bridge system.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2007.05a
• /
• pp.298-301
• /
• 2007

Magnesium alloy sheets have unique mechanical properties such as high in-plane anisotropy/asymmetry of yield stress and hardening response. The unusual mechanical behavior of magnesium alloys has been understood by the limited symmetry crystal structure of HCP metals or by deformation twinning. In the present study, the continuum plasticity models considering the unusual plastic behavior of magnesium alloy sheet were derived for a finite element analysis. A new hardening law based on two-surface model was developed to consider the general stress-strain response of metal sheets such as Bauschinger effect, transient behavior and the unusual asymmetry. Three deformation modes observed during the continuous tension/compression tests were mathematically formulated with simplified relations between the state of deformation and their histories. In terms of the anisotropy and asymmetry of the initial yield stress, the Drucker-Prager's pressure dependent yield surface was modified to include the anisotropy of magnesium alloys.

• The International Journal of Costume Culture
• /
• v.8 no.1
• /
• pp.32-42
• /
• 2005

This paper aims to propose fashion designs based on the application of art flower technique to translucent clothing material. For study method, firstly I looked into art flower applications occurred in modern trend since 2000 as well as theoretical research on art flower and transparency expressed as artificial beauty. Second, I attempt to express transparency in a variety of unique ways by using the art flower technique in producing clothes. Third, I utilized transparent flower with translucent clothing material and tried to suggest fashion design attempting mixture of new materials. As a result, firstly transparent image and material are well fitted in with modern trend and especially it was very suitable for expressing feminine beauty. Second, transparency was the element to suggest creative formative world in fashion design in regard to flower's beauty, various shapes and colors and to provide infinite materials as design motive. Third, the combination of knit clothing and plastic art flower displayed a new form of material combination. Especially as translucent material is fitted with trend such as function, lightness and variableness in modern times of the $21^{st}$ century, it presents beautiful combination with transparent flower. Fourth, Silk flower technique is variously used in art flower techniques. Various possibility ranges are presented such as flower was recreated with artificial image by silk flower technique to be newly expressed and various materials like aesthete film can be also expressed with silk flower technique.