• Journal of the Korean Wood Science and Technology
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• v.19 no.2
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• pp.40-55
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• 1991

To investigate the influence of cross section geometries on the behavior of composite beams in the case of small span to depth ratio and deep beams. the static flexural behavior of composite I-beams and Box- beams was evaluated. 12 types of composite I -beams composed of LVL flanges and particleboard or plywood web and 3 types of composite Box-beams composed of LVL flanges and plywood web were tested under one-point loading. The load-deflection curves were almost linear to failure, therefore, the behavior of tested composite beams was elastic. The theoretical flexural rigidity of composite beams was calculated and compared with observed flexural rigidity. The highest value was found in I-W type beams and the lowest value was found in G-P type beams. The difference between theoretical and observed flexural rigidity was small. Theoretical total deflection of tested composite beams was calculated using flexural rigidity and compared with actual deflection. Shear deflection of these beams was evaluated by the approximation method, solid crosss section method and elementary method. The difference between actual deflection and expected deflection was not found in D, E and F type beams. This defference was small in G, H and I type beams or Box-beam.

• Journal of the Korean Institute of Navigation
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• v.19 no.3
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• pp.11-19
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• 1995

When an automatic course keeping is introduced, as is quite popular in modern navigation, the closed-loop control system consists of autopilot device, power unit, steering gear, ship dynamics, and magnetic or gyrocompass. We derive mathematical models of each element of the automatic steering system. We provide a method of theoretical analysis on the propulsive energy loss related to automatic steering of ships in the open seas, taking account of the on-off(non-linear) characteristics of power unit. Also we paid attention to non-linear element installed in autopilot device, which is normally called weather adjuster. Next we make numerical calculation of the effects of autopilot control constants on the propulsive energy loss for two kinds of ship, a fishing boat and an ore carrier. Realistic sea and wind disturbances are employed in the calculation.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.48 no.4
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• pp.182-186
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• 1999

Evaluation of the AC losses in the HTS tapes which are used in electric power machines in one of the important topics in this field. This paper deals with the calculation and measurement of the magnetization loss in HTS tapes. Bean model is adopted for the theoretical calculation of the magnetization loss. Magnetization method is used for the measurement of the loss. Two types of the HTS tape model, multi-filamentary model and mono-filamentary model, are used to evaluate the magnetization loss in this paper. According to the results of the analysis, large discrepancy between the calculated and measured value is observed in multi-filamentary model is more useful than multi-filamentary model for the evaluation of the magnetization loss.

• Fire Science and Engineering
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• v.16 no.1
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• pp.24-29
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• 2002

The purpose of this study is developing the computer program for hydraulic design sprinkler systems have performed the means for the general use of network analysis method. The computer program is based on the theoretical concepts of the related Hazen-Williams equations, a modified Bernoulli equations, and the Hardy Cross method of pipe network analysis. Looped piping calculations are solved by using either the Hardy Cross method or the other iteration methods. While the other methods are solved using simultaneous equations, the Hardy Cross method is concerned with one loop at a time using reiterative process. Due to its simplicity the Hardy Cross method will be the primary method described in this thesis. The purpose of this study is to develope hydraulic calculation program by using algorithm for network analysis method. The development of computer program for the hydraulic design of sprinkler systems will perform the means in the performance-based sprinkler system design.

• Journal of Ocean Engineering and Technology
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• v.11 no.2
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• pp.91-99
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• 1997

This paper presents theoretical formulations and numerical computations for predicting first-and second-order hydrodynamic force on a ship advvancing in waves. The theoretical formulation leads to linearized radiation and diffration problems solving the three-dimensional Green function integral equations over the mean wetted body surface. Green function representing a translating and pulsating source potantial for infinite water depth is used. In order to solve integral equations for three dimentional flows using Green function efficiently, the Hoff's method is adopted for numerical calculation of the Green function. Based on the first-order solution, the mean seconder-order forces and moments are obtained by directly integrating second-order pressure over the mean wetted body surface. The calculated items are carried out for analyzing the seakeeping characteristics of Series 60. The calculated items are hydrodynamic coefficients, wave exciting forces, frequency response functions and addd resistance in waves.

• Journal of KSNVE
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• v.7 no.2
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• pp.331-345
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• 1997

A theoretical formulation for the analysis of free vibration of clamped-free cylindrical shells with plates attached at arbitrary axial position(s) was completed and it was programed to get the numerical results which yield natural frequencies and mode shape of the combined system of the plate and the shells. The frequencies and mode shapes from theoretical calculation were compared with those of commercial finite element code, ANSYS. In order to validate the theory, modal test was also performed by impact test and FFT analysis. The results shows good agreement with those of ANSYS and test results in frequencies and mode shapes. The method developed herein is likely to be used for the analysis of the free vibration of the clamped-free circular cylindrical shells with any kinds of lids such as hollow circular plates, conical shells, spherical shells, or semi-spherical shells.

• Journal of the Korean Institute of Navigation
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• v.22 no.2
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• pp.89-98
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• 1998

In the field of research of seakeeping quality, much development has been made incent years using the method of calculation based on the strip theory. It is indispensable to grasp quantitatively the seaworthiness of a ship in order to draw correct design at initial stage and to perform proper operations at sea services. In this paper, the responses of three fishing vessels are calculated using statistical and spectral analyzing method to get the characteristics of the motion response. From the theoretical result we know that the significant values of the pitching and rolling motion can be signiicantly affected by not only the ship's tonnage but also the mean wave period in spite of the similar sea environment. So we can apply these expected results to the safe maneuvering and fishing operations in rough weather conditions by combining environmental circumstance with the stability condition of vessels.

• Journal of Information Processing Systems
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• v.19 no.2
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• pp.164-172
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• 2023

Through theoretical proof and algorithm design, this paper numerically demonstrates that the three sampling methods of DDS are equivalent in amplitude-frequency characteristics. Depending on theoretical analysis, the article obtains the conclusion that 2 points are optimal when sampling at 2, 3, and 4 points. Built on the data results, this paper obtains the fractional form of the amplitude and phase of the DDS sampled signal; in addition, this paper also obtains the design parameters of the DDS post-stage filter. It also gives a control method for the calculation error when addressing this issue.

• Journal of Advanced Marine Engineering and Technology
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• v.11 no.3
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• pp.53-60
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• 1987

Steam ejector is a equipment which compresses the gases to desired discharge pressure. It is widely used for the evacuation systems because of its high working confidence. And recently it is used as the thermo-compressors in the various energy saving systems. Steam ejector is constructed of three basic parts; a suction chamber, a motive nozzle and a diffuser. The high velocity stream jet of steam emitted by the motive nozzle creats suction chamber, which draws the low pressure gases. The diffuser converts the kinetic energy of high velocity flow to pressure energy. It is not easy to determine the dimensions of a steam ejector met to the desired design condition, because that the expected suction rates must be obtained by reapeating the complicate calculation. And also such a calculation is concomitant with geometrical analysis for suction part and diffuser based on the stability of steam flow. Therefore, it is considered that the Computer-Aided Design (CAD) of steam ejector is a powerful design method. In this paper, computer program for steam ejector design is developed based on the theoretical research and the previous experimental results. And the determinating method of diffuser inlet angle and the velocity development profile of suction gas along to the diffuser are suggested. The validity of the development profile of suction gas along to the diffuser are suggested. The validity of the developed computer results with other's for the practical design calculation of a manufactured steam ejector.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.6C
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• pp.602-608
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• 2003

In this paper, we propose an efficient DCT calculation method for fast video encoding. We show that the SAD obtained in the motion estimation and compensation process is decomposed into the positive and negative terms. Based on a theoretical analysis, it is shown that the DCT calculation is classified into 4 cases - DCT Skip, Reduced_DCT1 , Reduced_DCT2, and original DCT- according to the positive and negative terms. In the proposed algorithm, one of 4 cases is used for DCT in order to reduce the computational complexity. The simulation results show that the proposed algorithm achieves computational saving approximately 25.2% without image degradation and computational overhead.