• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.12 no.1
• /
• pp.196-204
• /
• 2008

In this paper, we propose an efficient method to classify human facial impression using frontal face image. The features that represent the shape of eye, jaw and face are used. The proposed method employs PCA, LDA and SVM in series. PCA is used to project the feature space to a low dimensional subspace. LDA produces well separated classes in a low dimensional subspace even under severe variation. This results in good discriminating power for classification. SVM is used to classify the data. Human face has been classified for 8 facial impressions. The experiments have been performed for many face images, and show encouraging result.

• Journal of the Korean Society for Industrial and Applied Mathematics
• /
• v.25 no.2
• /
• pp.54-65
• /
• 2021

In this study, a two-dimensional thermoelastic problem under hyperbolic heat conduction theory with an internal heat source is considered. The general solution for the temperature field, stress components and displacement field are obtained using the reduced differential transform method. The stress and displacement components are obtained using the thermal stress function in the reduced differential transform domain. All the solutions are obtained in the form of power series. The special case with a time-dependent laser heat source has been considered. The problem is considered for homogeneous material with finite rectangular cross-section heated with a non-Gaussian temporal profile. The effect of the heat source on all the characteristics of a material is discussed numerically and graphically for magnesium material taking a pulse duration of 0.2 ps. This study provides a powerful tool for finding the solution to the thermoelastic problem with less computational work as compared to other methods. The result obtained in the study may be useful for the investigation of thermal characteristics in engineering and industrial applications.

• Journal of IKEEE
• /
• v.28 no.3
• /
• pp.432-439
• /
• 2024

This paper introduces an enhanced Selective Harmonic Elimination (SHE) technique of a single-phase Cascaded H-Bridge (CHB) Multilevel Inverter (MLI) for improving the reliability and power quality of a second life battery energy storage system (ESS). The technique involves solving non-linear transcendental equations derived from Fourier series offline to determine the optimal switching angles for the proposed SHE-PWM implementation. These angles are then applied in real-time via a Look-Up Table (LUT). The Levenberg-Marquardt algorithm, an iterative method, is employed in MATLAB to solve the equations and obtain the switching angles. The effectiveness of the proposed method is validated using PLECS simulation software and is compared with other conventional PWM techniques for MLIs.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.4
• /
• pp.117-122
• /
• 2018

A large-capacity three-phase system air conditioner recently includes an inverter circuit to reduce power consumption. The inverter circuit uses a DC voltage that comes from DC-link power capacitor with the function of rectifying, which means AC voltage to DC voltage using a diode. An electrolytic capacitor is generally used to satisfy the voltage ripple and current ripple conditions of a DC-link power capacitor used for rectifying. Reducing the capacitance of the capacitor decreases the size, weight, and cost of the circuit. This paper proposes an algorithm to reduce the input ripple current by combining the minimum point estimation phase locked loop (PLL) phase control and the average voltage d axis current control technique. When this algorithm was used, the input ripple current decreased by almost 90%. The current ripple of the DC-link capacitor decreased due to the decrease in input ripple current. The capacitor capacity can be reduced but the electrolytic capacitor has a heat generation problem and life-time limitations because of its large equivalent series resistance (ESR). This paper proposes a method to select a film capacitor considering the current ripple at DC-link stage instead of an electrolytic capacitor. The capacitance was selected considering the voltage limitation, RMS (Root Mean Square) current capacity, and RMS current frequency analysis. A $1680{\mu}F$ electrolytic capacitor can be reduced to a $20{\mu}F$ film capacitor, which has the benefit of size, weight and cost. These results were verified by motor operation.

• Journal of Advanced Navigation Technology
• /
• v.15 no.3
• /
• pp.349-354
• /
• 2011

In this paper, H-polarized scattering problems by a resistive strip grating with zero resistivity at strip-edges over a grounded dielectric plane according to the strip width and grating period, the relative permittivity and thickness of a dielectric layer, and incident angles of a transverse electric (TE) plane wave are analyzed by applying the Fourier-Galerkin Moment Method (FGMM). The tapered resistivity of resistive strips has zero resistivity at strip edges, then the induced surface current density on the resistive strip is expanded in a series of Chebyshev polynomials of the second kind as a orthogonal ploynomials. The sharp variations of the reflected power are due to resonance effects were previously called wood's anomallies, the numerical results for the reflected power are compared with those of uniform resistivity in the existing papers.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.17 no.1
• /
• pp.112-119
• /
• 1993

A strength and durability estimation system of involute cylindrical gears which are commonly used as power transmission devices is developed on the personal computer, which analyzed and/or evaluates the gear design and the service performance at the point of view of strength and durability. The typical considerations are the bending strength and the sunface durability, and the strength and durability estimations are carried out using the reliable standards of AGMA&ISO. In addition, the finite element analysis (FEM) of tooth bending stress is conducted in order to compare the real maximum stress with the estimaed bending stress by the standard. Therefore, the system is built so that the variables or factors considered differently in those standards and the strength & durability are appraised seperately by each method, and a series of the estimation processes is integrated into the system can be used in the initial design at the view point of strength and durability. And it is useful to the purpose of the trouble-shooting of gear system and the purpose of introducing the methods for maintaining design strength in service, with appraising the strength and durability after design or with appraising the influencing factors, as a whole. Therefore, this strength and durability estimation system can help the aim of automatic design of cylindrical gears.

• 한국태양에너지학회:학술대회논문집
• /
• 2011.11a
• /
• pp.278-281
• /
• 2011

This system can predict the maximum output about all illumination levels so that the PV system designer can design the system having the best efficiency. For the output prediction exact about the solar cell, that is the device the basis most in the PV system, the basis has to be in order to try this way. The solution based on Lambert W-function are presented to express the transcendental current-voltage characteristic containing parasitic power consuming parameters like series and shunt resistances. A simple and efficient method for the extraction of a single current-voltage (I-V) curve under the constant illumination level is proposed. With the help of the Lambert W function, the explicit analytic expression for I is obtained. And the explicit analytic expression for V is obtained. This analytic expression is directly used to fit the experimental data and extract the device parameters. The I-V curve of the solar cell was expressed through the modeling using Lambert W-function and the numerical formula where there is the difficulty could be logarithmically expressed This method expresses with the I-V curve through the modeling using Lambert W-function which adds other loss ingredients to the equation2 as to the research afterward. And the solar cell goes as small and this I-V curve can predict the power penalty in the system unit.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.10 no.2
• /
• pp.194-202
• /
• 2005

This paper proposes a new multi-level energy recovery sustaining driver for AC PDP(Plasma Display Panel), which solves the problems and maintains the merits of the conventional multi-level sustaining driver. While the conventional circuit improves the hard switching in the Weber circuit, there exist parasitic resonant currents in resonant inductors and Vs/2 sustaining period. Comparing the proposed circuit with the conventional circuit, the number of inductors are reduced by half, the parasitic resonant currents in resonant inductors are eliminated, and the hard switching problem is solved by CIM(Current Injection Method). Moreover the voltages across series-connected switching elements in the full bridge circuit are distributed equally by adopting NPC(Neutral Point Clamping) techniques. And circuit operations of the proposed circuit are analyzed for each mode and the validity is verified by the simulations using PSpice program and experimentation with a prototype drive circuit.

• Geomechanics and Engineering
• /
• v.7 no.5
• /
• pp.477-493
• /
• 2014

This study examines the behaviour of single micropiles subjected to axial tension or compression load in collapsible loess under in-situ moisture content and saturated condition. Five tension loading tests and five compression loading tests on single micropiles were carried out at a typical loess site of the Loess Plateau in Northwest China. A series of laboratory tests, including grain size distribution, specific gravity, moisture content, Atterberg limits, density, granular components, shear strength, and collapse index, were carried out during the micropile loading tests to determine the values of soil parameters. The loess at the test site poses a severe collapse risk upon wetting. The tension or compression load-displacement curves of the micropiles in loess, under in-situ moisture content or saturated condition, can generally be simplified into three distinct regions: an initial linear, a curvilinear transition, and a final linear region, and the bearing capacity or failure load can be interpreted by the L1-L2 method as done in other studies. Micropiles in loess should be considered as frictional pile foundations though the tip resistances are about 10%-15% of the applied loads. Both the tension and compression capacities increase linearly with the ratio of the pile length to the shaft diameter, L/d. For micropiles in loess under in-situ moisture content, the interpreted failure loads or capacities under tension are 66%-87% of those under compression. However, the prewetting of the loess can lead to the reductions of 50% in the tensile bearing capacity and 70% in the compressive bearing capacity.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.12
• /
• pp.8576-8584
• /
• 2015

Load forecasting is needed to make supply and demand plan for a stable supply of electricity. It is also necessary for optimal operational plan of the power system planning. In particular, in order to ensure stable power supply, long-term load forecasting is important. And regional load forecasting is important for tightening supply stability. Regional load forecasting is known to be an essential process for the optimal state composition and maintenance of the electric power system network including transmission lines and substations to meet the load required for the area. Therefore, in this paper we propose a forecasting method using SARIMA during the 12 months (long-term/mid-term) load forecasting by 16 regions of the South Korea.