• Advances in aircraft and spacecraft science
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• v.10 no.3
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• pp.281-302
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• 2023

In this paper, bending analysis of exponentially varying functionally graded (FG) plate is presented using trigonometric shear deformation theory (TSDT) considering both transverse shear and normal deformation effects. The in-plane displacement field consists of sinusoidal functions in thickness direction to include transverse shear strains and transverse displacement include the effect of transverse normal strain using the cosine function in thickness coordinate. The governing equations and boundary conditions of the theory are derived using the virtual work principle. System of governing equations, for simply supported conditions, Navier's solution technique is used to obtain results. Plate material properties vary across thickness direction according to exponential distribution law. In the current theory, transverse shear stresses are distributed accurately through the plate thickness, hence obviates the need for a shear correction factor. TSDT results are compared with those from other theories to ensure the accuracy and effectiveness of the present theory. The current theory is in excellent agreement with the semi-analytical theory.

• IEMEK Journal of Embedded Systems and Applications
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• v.9 no.6
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• pp.323-334
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• 2014

In this paper, we proposed indoor positioning system with improved accuracy. The proposed indoor location measurement system is based pedestrian location measurement method that use the embedded sensor of smartphone. So, we do not need wireless external resources, such as GPS or WiFi signals. The conventional methods measure indoor location by generating a movement route of pedestrian by step and direction recognition. In this paper, to correct the direction sensor error, we use the common feature of the normal indoor floor map that the indoor path is lattice-structured. And we quantize moving directions depending on the direction of indoor path. In addition, we propose moving direction measuring method using geomagnetic sensor and gyro sensor to improve the accuracy. Also, the proposed step detection method uses angle and accelerometer sensors. The proposed step detection method is not affected by the posture of the smartphone. Direction errors caused by direction sensor error is corrected due to proposed moving direction measuring method. The proposed location error correction method corrects location error caused by step detection error without the need for external wireless signal resources.

• 한국정보통신설비학회:학술대회논문집
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• 2009.08a
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• pp.382-386
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• 2009

Online or sequential learning is one of the most basic and powerful method to train neuron network, and it has been widely used in disease detection, weather prediction and other realistic classification problem. At present, there are many algorithms in this area, such as MRAN, GAP-RBFN, OS-ELM, SVM and SMC-RBF. Among them, SMC-RBF has the best performance; it has less number of hidden neurons, and best efficiency. However, all the existing algorithms use signal normal distribution as kernel function, which means the output of the kernel function is same at the different direction. In this paper, we use multi-variable normal distribution as kernel function, and derive EKF learning formulas for multi-variable normal distribution kernel function. From the result of the experience, we can deduct that the proposed method has better efficiency performance, and not sensitive to the data sequence.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.05a
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• pp.114-117
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• 2007

In the present study, the effects of initial texture on the twinning formation of AZ31 Mg rolled sheet was investigated. Uniaxial compression tests were performed on samples cut along the normal direction and rolling direction of rolled AZ31 Mg alloy sheet at various temperatures (RT, 200, 250, 300, 350, $400^{\circ}C$) with the 0.01/s strain rate. Pole figure of rolling planes showed that basal planes of most gain were located parallel to the rolling direction. After compression test, microstructures and stress-strain curves results indicated that active deformation twining occurred only at the specimen cut along the rolling direction. The slip-twin transition with the increase of temperature was also investigated.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.550-553
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• 2008

In this paper, experiments of air-breathing proton exchange membrane fuel cell (PEMFC) for mobile devices were carried out according to the cathode conditions. These conditions are defined by the cathode flow field plate type (the channel type, the open type) and the cathode surface direction. Single cell and 6-cell stack were used in this experiments. The experimental results showed that the open type cathode flow field plate gave better performance for small size PEMFCs because the open type cathode plate allowed better air convection than the channel type cathode plate. In the experiments related to the direction of the slits on the cathode flow field plate, the horizontal slit cell was better than the vertical slit cell. With respect to the cathode surface direction, when the cathode surface is placed in the direction normal to the ground, PEMFC generated more stable power in the mass transport loss region.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.472-475
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• 2014

Abnormal cab vibrations in the Y direction in commercial vehicles during driving(70~90kph) are not common vibrations that happen to vehicles during driving and can be an obstacle to normal driving. This study conducted Operation Deflection Shape(ODS) testing to identify the causes of those abnormal cab vibrations and find solutions for them and also a sine sweep test to find resonance and frequency in the cab suspension system and set directions for improvement. The study also altered the shape of the bush inner part for changes to the rigidity features of the cab bush in the Y direction and revised the design with optimal rigidity in the Y direction, thus improving abnormal cab vibrations in the Y direction during driving.

• Korean Journal of Applied Biomechanics
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• v.23 no.4
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• pp.335-345
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• 2013

The purpose of this study was to investigate the effects of foot type and ankle joint fatigue levels on the trajectories of center of pressure and center of mass during a single-leg stance. The study subjects included 24 healthy women (normal foot group, n=10; pronated foot group, n=14). Ankle joint muscle fatigue was induced by using an isokinetic dynamometer, where the fatigue levels were measured on plantar flexion and dorsiflexion at angular velocities of $30^{\circ}/s$ at 50% and 30% of the peak torque of ankle plantar flexion. Following assessments in the anteroposterior direction according to the level of fatigue, the pronated foot group showed decreased single-leg stance ability at 50% and 30% of the fatigue level. Moreover, the normal foot group showed better single-leg stance ability than the pronated foot group at 30% of the fatigue level. Following assessments in the mediolateral direction, we noted that the single-leg stance ability did not differ significantly according to the levels of fatigue or foot type. In conclusion, ankle plantar flexion at 50% and 30% of the peak torque reduced the ability of the pronated foot group to achieve a single leg stance in the anteroposterior direction. Moreover, the normal foot group showed better single-leg stance ability than the pronated foot group.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.7
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• pp.655-663
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• 2013

Several studies of film cooling were accomplished with a secondary flow channel parallel to the main flow. In real turbine blades, however, the direction of the secondary flow channel is generally normal to the main flow. Thus, this study performs a numerical analysis to investigate the effects of the direction of secondary flow on the effectiveness of double-jet film cooling. The blowing ratio is 1 and 2, and the lateral injection angle is $22.5^{\circ}$. The parallel channel case creates a well-developed anti-kidney vortex with a blowing ratio of 1, and the laterally averaged film cooling effectiveness of the parallel channel is enhanced compared to the normal channel. The normal channel shows higher performance with a blowing ratio of 2. Both cases show high film cooling effectiveness. These phenomena can be attributed to a high blowing ratio and flow rate rather than an anti-kidney vortex.

• Proceedings of the Safety Management and Science Conference
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• 2001.05a
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• pp.179-184
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• 2001

The objective of this work is to develop the capability to analyze accurately the mixed-mode propagation of a crack in composite structures with elastic orthotropic material stiffness properties and anisotropic material strength characteristics. We employ the normal stress ratio theory to predict the direction of crack extension. It is shown that the angle of crack extension can be altered by the use of second order term in the series expansion is important for the accurate determination of crack growth direction.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 1999.02a
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• pp.109-112
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• 1999

The normal zone propagation (NZP) velocity and V-I characteristics of two Bi-2223 pancake coils with different Ag/SC ratio were investigated by experiment. Non-uniformity of Ic and broad restive transition was oberserbed in two coils. The NZP velocity of azimuth direction is faster than radius direction, and the NZP velocity of coil with higher Ag/SC ratio is faster than another coil with lower Ag/SC ratio.