• The Transactions of the Korean Institute of Power Electronics
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• v.28 no.1
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• pp.30-38
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• 2023

In this paper, a constant current(CC) and constant voltage(CV) control method using a primary-side regulated(PSR) fly-buck converter is proposed. Because the primary-side structure of the fly-buck converter is the same as that of the synchronous buck converter, it always operates in continuous conduction mode(CCM). Therefore, in the proposed method, the load information on the secondary side can always be easily estimated by measuring the primary inductor current at the midpoint of the switch-on period. An accurate CC/CV control can be achieved through simple calculations based on this estimated information. Consequently, the proposed method is advantageous for optimizing the control performance of the PSR converter. The validity of the proposed control was verified using a 5 W prototype of a PSR fly-buck converter. The experimental results confirmed that the current reference of 500 mA was followed within the error range of 1.2%, and that the voltage reference of 12 V was followed within the error range of 1.8% despite the indirect control of the load current and output voltage from the primary side.

• Journal of the Korea Computer Graphics Society
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• v.6 no.3
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• pp.17-23
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• 2000

Recently, as it is growing concern about Non-Photo-Realistic Rendering, several researchers are studying to simulate conventional artistic expressions such as pen-and-ink, watercolor and impressionism techniques. In this paper, we describe a mosaic technique using color paper tore by hands. We will also try to represent real paper by using random midpoint displacement method (RMD) to express a shape of paper tore by hands without using cutters or scissors. The Perlin's noise function is used to express texture of paper.

• Structural Engineering and Mechanics
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• v.56 no.4
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• pp.535-548
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• 2015

A series of experimental results on thin mild steel plates clamped at the boundary subjected to gas detonation shock loading are presented. Detonation occurred by mixing Acetylene (C2H2)-Oxygen (O2) in various volume ratio and different initial pressure. The applied impulse is varied to give deformation in the range from 6 mm to 35 mm. Analytical modeling using energy method was also performed. Dependent material properties, as well as strain rate sensitivity, are included in the theoretical modeling. Prediction values for midpoint deflections are compared with experimental data. The analytical predictions have good agreement with experimental values. Moreover, it has been shown that the obtained model has much less error compared with those previously proposed in the literature.

• Journal of Multimedia Information System
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• v.4 no.4
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• pp.239-242
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• 2017

This paper proposes a low-cost method for counting people based on blob detection and blob tracking. Here background subtraction is used to detected blob and then the blob is classified with its width and height to specify that the blob is a person. In this system we first define the area of entry and exit point in the video frame. The counting of people starts when midpoint of the people blob crosses the defined point. Finally, total number of people entry and exit from the place is displayed. Experiment result of this proposed system has high accuracy in real-time performance.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2006.05a
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• pp.99-104
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• 2006

A semi-Lagrangian finite element scheme with objective time stepping algorithm for solving viscoelastic flow problem is presented. The convection terms in the momentum and constitutive equations are treated using a quasi-monotone semi-Lagrangian scheme, in which characteristic feet on a regular grid are traced backwards over a single time-step. Concerned with the generalized midpoint rule type of algorithms formulated to exactly preserve objectivity, we use the geometric transformation such as pull-back, push-forward operation. The method is applied to the 4:1 planar contraction problem for an Oldroyd B fluid for both creeping and inertial flow conditions.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1080-1085
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• 2003

The flow of electrical current through a microscopic actual contact spot between two conductors is influenced by the flow through adjacent contact spots. A smoothed version of this interaction effect is developed and used to predict the contact resistance when the statistical size and spatial distribution of contact spots is known. To illustrate the use of the method, an idealized fractal rough surface is defined using the random midpoint displacement algorithm and the size distribution of contact spots is assumed to be given by the intersection of this surface with a constant height plane. With these assumptions, it is shown that including finer scale detail in the fractal surface, equivalent to reducing the sampling length in the measurement of the surface, causes the predicted resistance to approach the perfect contact limit.

• Journal of Chest Surgery
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• v.30 no.8
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• pp.833-837
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• 1997

Congenital tracheal stenosis is very rare, but it leads to life threatening obstruction in infancy and childhood. Recently, we experienced two cases of congenital tracheal stenosis, involving half of the distal trachea. We adopted slide tracheoplasty procedure Proposed by Peter Goldstraw Tracheoplasty was performed by dividing the stenosis at midpoint, incising the proximal and distal narrow segments vertically on opposite anterior and posterior surfaces, and sliding these together. On case 1, the patient':s now doing well. On case 2, the patient succumbed due to anastomotic disruption at postoperative ay 4.

• Journal of Power Electronics
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• v.15 no.4
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• pp.920-928
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• 2015

Transformerless solar inverters have a higher efficiency than those with an isolation link. However, they suffer from a leakage current issue. This paper proposes a family of single phase six-switch transformerless inverter topologies with an ac bypass circuit to solve the leakage current problem. These circuits embed two unidirectional freewheeling current units into the midpoint of a full bridge inverter, to obtain a freewheeling current path, which separates the solar panel from the grid in the freewheeling state. The freewheeling current path contains significantly fewer devices and poor performance body diodes are not involved, leading to a higher efficiency. Meanwhile, it is not necessary to add a voltage balancing control method when compared with the half bridge inverter. Simulation and experiments are provided to validate the proposed topologies.

• Structural Engineering and Mechanics
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• v.20 no.3
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• pp.293-312
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• 2005

In this paper, free vibration of rotating beam with random properties is studied. The cross-sectional area, elasticity modulus, moment of inertia, shear modulus and density are modeled as random fields and the rotational speed as a random variable. To study uncertainty, stochastic finite element method based on second order perturbation method is applied. To discretize random fields, the three methods of midpoint, interpolation and local average are applied and compared. The effects of rotational speed, setting angle, random property variances, discretization scheme, number of elements, correlation of random fields, correlation function form and correlation length on "Coefficient of Variation" (C.O.V.) of first mode eigenvalue are investigated completely. To determine the significant random properties on the variation of first mode eigenvalue the sensitivity analysis is performed. The results are studied for both Timoshenko and Bernoulli-Euler rotating beam. It is shown that the C.O.V. of first mode eigenvalue of Timoshenko and Bernoulli-Euler rotating beams are approximately identical. Also, compared to uncorrelated random fields, the correlated case has larger C.O.V. value. Another important result is, where correlation length is small, the convergence rate is lower and more number of elements are necessary for convergence of final response.

• Structural Engineering and Mechanics
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• v.54 no.3
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• pp.433-451
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• 2015

This paper focuses on large deflection static behavior of edge cracked simple supported beams subjected to a non-follower transversal point load at the midpoint of the beam by using the total Lagrangian Timoshenko beam element approximation. The cross section of the beam is circular. The cracked beam is modeled as an assembly of two sub-beams connected through a massless elastic rotational spring. It is known that large deflection problems are geometrically nonlinear problems. The considered highly nonlinear problem is solved considering full geometric non-linearity by using incremental displacement-based finite element method in conjunction with Newton-Raphson iteration method. There is no restriction on the magnitudes of deflections and rotations in contradistinction to von-Karman strain displacement relations of the beam. The beams considered in numerical examples are made of Aluminum. In the study, the effects of the location of crack and the depth of the crack on the non-linear static response of the beam are investigated in detail. The relationships between deflections, end rotational angles, end constraint forces, deflection configuration, Cauchy stresses of the edge-cracked beams and load rising are illustrated in detail in nonlinear case. Also, the difference between the geometrically linear and nonlinear analysis of edge-cracked beam is investigated in detail.