• Communications for Statistical Applications and Methods
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• v.18 no.5
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• pp.645-655
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• 2011

Chandrasekar et al. (2004) introduced a generalized Type-II hybrid censoring. In this paper, we propose generalized doubly Type-II hybrid censoring. In addition, this paper presents the statistical inference on the scale parameter for the half logistic distribution when samples are generalized doubly Type-II hybrid censoring. The approximate maximum likelihood(AMLE) method is developed to estimate the unknown parameter. The scale parameter is estimated by the AMLE method using two di erent Taylor series expansion types. We compar the AMLEs in the sense of the mean square error(MSE). The simulation procedure is repeated 10,000 times for the sample size n = 20; 30; 40 and various censored samples. The $AMLE_I$ is better than $AMLE_{II}$ in the sense of the MSE.

• Publications of The Korean Astronomical Society
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• v.2 no.1
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• pp.47-60
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• 1985

Four observational astronomical item, have been pilottested with a 150mm refracting telescope in order to layout the detailed procedures for the suggested (inquiry) activities listed in the high school earth science curriculum and to contrive some adequate instructions for students stressed on how to make proper treatments with the collected materials. The tested items were of sunspots' motion, the size of lunar craters, the Galilian satellites' revolution, and the galactic distribution of stars. Following series of activities are suggested with respect to the way of collecting observational data and of giving proper instruction to students in class: 1) Photography and other material, he made by teacher and/or extracurricular group of students; 2) Replicas (xeroxed, photographs, Or slides) he made from the collected materials, '0 that they are available to all the students in class; 3) Quantative analyses, be taken as student' activity.

• Journal of the Korea Concrete Institute
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• v.12 no.5
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• pp.121-130
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• 2000

Currently, in evaluating a flexural strength of a concrete member, the effect of specimen depth has not been systematically studied, even though its effect on ultimate strength of a section is very important. For all types of loading conditions, the trend is that the strength of a member tends to decrease when the member depth increases. In this study, the influence of specimen depth on flexural compressive strength of concrete member was examined experimentally. A series of C-shaped specimens subjected to axial compressive force and bending moment were tested using three geometrically similar specimens with different length-to depth ratios (h/c = 1, 2 and 4) which have compressive strength of 55 MPa. The results indicate that the flexural compressive strength decreased as the specimen depth increased. A model equation was derived based on regression analyses of the experimental data. Also, the results show that ultimate strain decreases as the specimen depth increases. Finally, a general model equation for the depth effect is proposed.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.988-989
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• 2008

This paper describes a rapid pulsed power charging system for pulsed power application. It is capable of charging 35kJ/s energy up to 0.47uF 25kV within 3ms and maximum pulse repetition rate of 300 pps can be achieved. The charger is designed based on three-phase series resonant inverter followed by air cooled set-up transformers thus it has many advantages of lower weight, small size and high efficiency compared with large bulky traditional pulse charger system. Detail design procedure of resonant inverter and high voltage transformers is explained. Experimental results carried out at different condition and its results shows 90% efficiency at full load condition.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.2
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• pp.252-259
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• 2001

Computational study has been performed to observe the flow characteristics of combustion chamber for geometrical modification in municipal solid waste incinerator. A series of geometrical modification has been carried out as an attempt to reduce the size of recirculation zone, to obtain uniform flow field in the secondary combustion chamber and to improve the mixing of combustion gas. Two dimensional non-reacting turbulent flow has been studied as the first step to get such goals and the result of design optimization is presented. In addition, three dimensional non-reacting and reacting flow analyses were performed to verify the validity of two dimensional approach.

• Proceedings of the KSMRM Conference
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• 2003.10a
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• pp.23-23
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• 2003

To evaluate clinical visualization of intracranial aneurysms between 3D-TOF MRA with 3.0T MR and CTA with 16-slices MDCT. In a prospective series, 12 patients with 16 aneurysms were studies with 3D-TOF MRA and CTA. MRA were performed on a GE Signa 3.0 T system (Signa VH/i, GE) with 25/3/20 (TR/TE/FA). CTA were peformed on a 16 slice MDCT (Sensation 16, Somatom, Siemens) with IV shooting of 80 ml iodinated contrast mediumat antecubital vein at a rate of 3.5 ml/sec. Four among 12 patients underwent DSA for surgery. Size, shape, neck and parent vessel of aneurysms were evaluated for comparison of visualization and detectability of aneurysms.

• 한국전산유체공학회:학술대회논문집
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• 2007.04a
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• pp.177-181
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• 2007

Present study examines the numerical issues of cell structure simulation for various regimes of detonation phenomena ranging from weakly unstable to highly unstable detonations. Inviscid fluid dynamics equations with $variable-{\gamma}$ formulation and one-step Arrhenius reaction model are solved by a MUSCL-type TVD scheme and 4th order accurate Runge-Kutta time integration scheme. A series of numerical studies are carried out for the different regimes of the detonation phenomena to investigate the computational requirements for the simulation of the detonation wave cell structure by varying the reaction constants and grid resolutions. The computational results are investigated by comparing the solution of steady ZND structure to draw out the minimum grid resolutions and the size of the computational domain for the capturing cell structures of the different regimes of the detonation phenomena.

• Proceedings of the KSME Conference
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• 2001.06a
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• pp.883-888
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• 2001

The theoretical method is developed to investigate the effects of ring stiffeners on free vibration characteristics and transient response for the ring stiffened composite cylindrical shells subjected to the impulse pressure loading. In the theoretical procedure, the Love's thin shell theory combined with the discrete stiffener theory to consider the ring stiffening effect is adopted to formulate the theoretical model. The concentric or eccentric ring stiffeners are laminated with composite and have the uniform rectangular cross section. The modal analysis technique is used to develop the analytical solutions of the transient problem. The analysis is based on an expansion of the loads, displacements in the double Fourier series that satisfy the boundary conditions. The effect of stiffener's eccentricity, number, size, and position on transient response of the shells is examined. The theoretical results are verified by comparison with FEM results.

• Proceedings of the KIPE Conference
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• 2010.07a
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• pp.242-243
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• 2010

This paper investigates a power supply of medium voltage with enhanced ignition characteristics for plasma torch. Series resonant half-bridge topology is presented to be a suitable ignition circuitry. The ignition circuitry is integrated into the main power conversion system of a multi-phase staggered three-level dc-dc converter with a diode front-end rectifier. The plasma torch rated for 3MW, 2kA and having the physical size of 1m long is selected to be a high enthalpy source in waste disposal system. The steady-state and transient operations of plasma torch are simulated. The parameters of Cassie-Mary arc model are calculated based on 3D magneto-hydrodynamic simulations. Circuit simulation waveform shows that the ripple of arc current can be maintained within ${\pm}10%$ of its rated value under the existence of load disturbance. This power conversion configuration provides high enough ignition voltage around 5KA during ignition phase and high arc stability under the existence of arc disturbance noise resulting in a high-performance plasma torch system.

• The Transactions of the Korean Institute of Power Electronics
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• v.17 no.2
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• pp.121-128
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• 2012

In this paper, a new planar transformer with a novel core configuration that can regulate the leakage inductance is proposed and described in detail. In order to design the slim size power system for flat panel TV, Two planar transformers applied to LLC resonant converter are connected in series at primary and in parallel by the center-tap winding at secondary. In this paper, a 300W low profile LLC resonant converter was built and tested to verify the proposed planar transformer.