• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제49권3호
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• pp.165-171
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• 2000

This paper proposes a technique to design of air-core type Linear DC Motor(LDM) by using Equivalent Magnetizing Current(EMC) method and has performed its dynamic analysis. The magnetic flux density differ in accordance with airgap position due to difference of mechanical and magnetic air gap length and the coil shape has an influence on the thrust. Therefore, the analysis of magnetic field due to the magnets is carried out by EMC. The phenomena according to the various coil various coil shape under the same Magneto Motive Force(MMF) has been analyzed and its result is applied to the design process. The appropriateness of the proposed technique is confirmed by Finite Element Method(FEM) and its dynamic analysis is carried out from the coupling of the electrical circuit equation and mechanical kinetic equation.

• 한국자동차공학회논문집
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• 제22권7호
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• pp.16-22
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• 2014

Automotive NVH on brake operation is mainly caused by a coupling action of vehicle speed and inter parts friction and its frequency occurs over a broad band of 0.1 kHz~10 kHz. Especially, squeal noise, being a self-excited vibration generated by friction force between drum and lining, occurs over 1 kHz and consequently dynamic instability is induced when friction energy is applied to a brake vibration system. The squeal strongly depends on nonlinear properties influenced by the material of lining, velocity of vehicle, and the dynamic properties of a brake system. The dynamic properties are considered as a main influential design factor to squeal noise, however the analysis of the properties are rarely facilitated due to arbitrariness of shape by wearing down. In this paper, we research generating tendency of squeal noise through complex eigenvalue analysis, tracking drum brake's unstable modes in accordance with the wear shape of drum and lining such as tapered and bellmouth shape, and analyze computed unstable modes by variable shapes.

• International Journal of Aeronautical and Space Sciences
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• 제18권3호
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• pp.485-497
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• 2017

The pogo phenomenon refers to a type of multidiscipline-related instability found in space launch vehicles. It is caused by coupling between the fuselage structure and other structural propulsion components. To predict the pogo phenomenon, it is essential to undertake adequate structural modeling and to understand the characteristics of the feedlines and the propulsion system. To do this, a modal analysis is conducted using axisymmetric two-dimensional shell elements. The analysis is validated using examples of existing launch vehicles. Other applications and further plans for pogo analyses are suggested. In addition, research on the pogo phenomenon of Saturn V and the space shuttle is conducted in order to constitute a pogo stability analysis using the results of the present modal analysis.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.1347-1348
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• 2007

In this paper, ITO gate electrode surface was modified using $O_2$ plasma and organic gate insulating layers were deposited on the ITO surface using plasma polymerization technique. In order to investigate the influence of the plasma coupling method and plasma conditions on the plasma polymerized methyl methacrylate (ppMMA) thin film properties, inductively coupled (ICP) and capacitively coupled plasma (CCP) were used to generate the plasma and the plasma parameters were varied. The ppMMAs were investigated using atomic force microscopy (AFM) and a Fourier Transform Infrared (FT-IR) spectroscopy. Dielectric constants of the ppMMA thin films were investigated using a impedance analyzer (HP4192A, LF Impedance Analyzer). Current-Voltage (I-V) characteristics of the organic thin film transistors (OTFTs) were investigated using a source measurement unit (SMU: Keithley 2612). Proposed method can be applied to dry-process to fabricate OTFTs during overall fabricating steps.

• Journal of Photoscience
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• 제2권1호
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• pp.19-25
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• 1995

Picosecond time-resolved and static protein fluorescence spectra and absorption spectra of octopus rhodopsin, a photorecepting protein, are measured and compared with those of bacteriorhodopsin, a photon-induced proton pumping protein, to understand the protein conformations and functions of octopus rhodopsin and its deprotonated photocycle intermediate. The bluer and weaker absorption of retinal indicates that octopus rhodopsin is better in thermal noise suppression but less efficient in light harvesting than bacteriorhodopsin. The protein fluorescence of octopus rhodopsin shows the characteristic of Trp only and the uantum efficiency and lifetime variations may result primarily from variations in the coupling strength with the retinal. The stronger intensity by four times and larger red shift by 12 nm of fluorescence suggest that octopus rhodopsin has more open and looser structure compared with bacteriorhodopsin. Fluorescence decay profiles reveal two decay components of 300 ps (60%) and 2 ns (40%). The deprotonation of protonated Schiff's base increases the shorter decay time to 500 ps and enhances the fluorescence intensity by 20%. The fluorescence and its decay time from Trp residues near retinal are influenced more by the deprotonation. The increase of fluorescence intimates that protein structure becomes loosened and relaxed further by the deprotonation of protonated Schiff's base. The driving force of sequential changes initiated by absorption of a photon is too exhausted after the deprotonation to return the intermediate to the ground state of the begun rhodopsin form.

• 한국소음진동공학회논문집
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• 제17권3호
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• pp.264-273
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• 2007

A smart panel with structural sensors and actuators for minimizing noise radiation or transmission is described in the paper with the concept of active structural acoustical control. The sensors and actuators are both quadratically shaped piezoelectric polyvinylidene fluoride(PVDF) Polymer films to implement a volume velocity sensor and uniform force actuator respectively. They are collocated on either side of the panel to take advantage of direct velocity feedback(DVFB) strategy, which can guarantee a robust stability and high performance as long as the sensor-actuator response is strictly positive real(SPR). However, the measured sensor-actuator response of the panel showed unexpected result with non-SPR property. In the paper, the reason of the non-SPR property is investigated by theoretical analysis, computer simulation and experimental verification. The investigation reveals that the arrangement of collocated piezoelectric PVDF sensor and actuator pair on a panel is not relevant to get a high feedback gain and good performance with DVFB strategy.

• Bulletin of the Korean Chemical Society
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• 제11권6호
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• pp.560-563
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• 1990

A.c. susceptibility for $Bi_{1.4}Pb_{0.6}Sr_2Ca_2Cu_{3.6}O_x$ superconductor is measured as a function of temperature at different value of a.c. magnetic field amplitude. Two transition steps are attributed to the intergranular and intragranular properties. Based on Bean's critical state model, intergranular critical current density, $J_c^{gb}$ (11 $A/cm^2$ at 77 K) and intragranular critical current density, $J_c^g (7{\times}10^3\;A/cm^2$ at 100 K) are estimated. The low values of $J_c^{gb}$and $J_c^g$ reflect a poor nature of coupling between grains and the low pinning force density of intragrain in $Bi_{1.4}Pb_{0.6}Sr_2Ca_2Cu_{3.6}O_x$ superconductor.

• Archives of Pharmacal Research
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• 제6권1호
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• pp.69-73
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• 1983

It was reported from our laboratory that the rate of deterioration of the force of contraction was slower in heart from Panax ginseng extract treated rats. Present investigation was designed to elucidate the mechanism of the slow deterioration of contractility of ginseng treated hearts. Therefore, $^{45}Ca^{2+}$ Uptake by sarcoplasmic reticulum (SR) isolated from ginseng treated rate and control rats was studied. Rate weighing 150-250g were administered orally with ginseng ethanol extract (100mg/kg) for 10 days. Cardiac SR was isolated by differential centrifugation and $^{45}Ca^{2+}$ uptake was assessed by the Millipore method. Freshly isolated SR from treated as well as control animals did not show any differences, but after incubation for 30 and 60 min at 37.deg.C, $^{45}Ca^{2+}$ uptake of control animal SR was found to be greatly depressed. The SR of treated animal possessed a greater degree of resistance to incubation. Thus it can be concluded that ginseng may have an ability to sustain the normal function of the heart by sustaining Ca accumulation by SR involved with the excitationcontraction coupling processes.

• Ocean Systems Engineering
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• 제8권4호
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• pp.441-459
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• 2018

A coupled dynamic analysis of a semisubmersible-type FOWT has been carried out in time domain under the combined action of irregular wave and turbulent wind represented respectively by JONSWAP spectrum and Kaimal spectrum. To account for the turbine-floater motion coupling in a more realistic way, the wind turbulence has been incorporated into the calculation of aerodynamic loads. The platform model was referred from the DeepCwind project and the turbine considered here was the NREL 5MW Baseline. To account for the operationality of the turbine, two different environmental conditions (operational and survival) have been considered and the aerodynamic effect of turbine-rotation on actual responses of the FOWT has been studied. Higher mean offsets in surge and pitch responses were obtained under the operational condition as compared to the survival condition. The mooring line tensions were also observed to be sensitive to the rotation of turbine due to the turbulence of wind and overestimated responses were found when the constant wind was considered in the analysis. Additionally, a special analysis case of sudden shutdown of the turbine has also been considered to study the swift modification of responses and tension in the mooring cables.

• International Journal of Naval Architecture and Ocean Engineering
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• 제11권1호
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• pp.233-243
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• 2019

In this paper, numerical and experimental studies are performed to investigate the liquid impact on a free falling wedge. In the numerical simulation, the structure is assumed to be rigid and the elastic response is ignored. The fully nonlinear coupling between wedge and water is considered by an auxiliary function method based on the Boundary Element Method (BEM). At the intersection of the wedge surface and liquid surface, two coincident nodes are used to decouple the boundary conditions. The Eulerian free surface conditions in the local coordinate system are adopted to update the deformed free surface. In the experiments, five pressure sensors are fixed on each side of the wedge which is released from an experimental installation. Steel and aluminum wedges that have different structural elasticity are used in the experiments to investigate the influence of structural elasticity on the impact force. Numerical results are compared with experimental data and they agree very well. The influence of fluid gravity, body mass, initial entry speed and deadrise angle on the impact pressure are further investigated.