• Journal of Advanced Marine Engineering and Technology
• /
• 제29권7호
• /
• pp.785-794
• /
• 2005

Modern ship hulls of large oil carriers and container carrers have become more flexible with scantling optimization and increase in ship length. On the other hand. as the demand for power has increased with the ship size. shaft diameters have become larger and stiffer. Consequently. the alignment of the propulsion system has become more sensitive to hull girder deflections. resulting in difficulties in analyzing the alignment and conducting the alignment procedure. Accordingly. the frequency of shaft alignment related bearing damages has increased significantly in recent years. The alignment related damages are mostly attributed to inadequate analyses. changes in the design of the vessel. shipyards' practices in conducting the alignment. and a lack of well defined analytical criteria. The hull deflections should be considered at the design stage to minimize the bearing damage caused by hull deflection. Hull deflections can be estimated by analytical approach and reverse calculation using the measured data. The hull girder deflection analysis using the reverse calculation will be introduced in this paper.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• 제10권6호
• /
• pp.658-665
• /
• 1998

This paper investigates local exhaust effectiveness in a room with a supply and an exhaust slots on the ceiling. The mean age of air is an indicator of supply effectiveness, while the mean residual life time can be used as an indicator of exhaust effectiveness. The distribution of local mean residual life time in a space is calculated by four different numerical procedures. The reverse-flow calculation method has been proved to show quite accurate results while it can save considerable amount of computation time and efforts, compared to the method by its original definition. It is concluded that the diffusion term in the equation of mean residual life time can be neglected. The spatial and temporal diffusion characteristics of the contaminant are also discussed.

• Membrane Journal
• /
• 제2권1호
• /
• pp.33-48
• /
• 1992

OSRO process was developed and it was confirmed more effective in ethanol concentrating process comparing to reverse osmosis process. It may be industrialized if more effective membrane for OSRO and reverse osmosis, which indicate the value greater than zero, it was shown that OSRO process was more effective than reverse osmosis for the ethanol concentration process. The decrease of feed concentration and flow rate and the increase of applied pressure made more effective operating conditions in OSRO process to concentrate ethanol. From the numerical esults for the multi-plates, theoretical DC values of reverse osmosis and OSRO process was increased as the umber of stages increased. DC values were increased with the increase of applied pressure in same number of stages. The theoretical values of DC by numerical calculation were corresponded to the experimental values within 15% tolerance. DC value was increased proportional to applied pressure and osmotic sink solution flow rate but it was decreased proportional to feed concentration and flow rate. The numerical calculation over the wide ranges inclading experimental condition was proposed in this study.

• The Journal of the Acoustical Society of Korea
• /
• 제26권5호
• /
• pp.214-219
• /
• 2007

This paper proposes a new IFFT(Inverse Fast Fourier Transform) algorithm, which is proper for IMDCT(Inverse Modified Discrete Cosine Transform) of MPEG-2 AAC(Advanced Audio Coding) decoder. The $2^n$(N-point) type IMDCT is the most powerful among many IMDCT algorithms, however it includes IFFT that requires many calculation cycles. The IFFT used in $2^n$(N-point) type IMDCT employ the bit-reverse data arrangement of inputs and N/4-point complex IFFT to reduce the calculation cycles. We devised a new data arrangement method of IFFT input and $N/4^{n+1}$-type IFFT and thus we can reduce multiplication cycles, addition cycles, and ROM size.

• Transactions of the Korean Society of Automotive Engineers
• /
• 제6권2호
• /
• pp.178-190
• /
• 1998

We have developed a planar impact model with a capability of reverse calculation to reconstruct various types of automobile collisions. This topic is the main part of what is referred to as accident reconstruction. The model uses the principle of impulse and momentum, and introduces a restitution coefficient and an impulse ratio at the impact center. Based on the car-to-car collision test results, we present how to estimate the restitution coefficient and the impulse ratio from some impact conditions. To validate the model and improve its reliability in accident analysis, the collision analysis has been performer with the estimated parameters. The analysis and experimental results agree well in the kinetic energy loss and the post-impact velocity.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 한국정밀공학회 1996년도 추계학술대회 논문집
• /
• pp.787-792
• /
• 1996

The method of manipulation by striking a part and letting it slide until it comes to rest, has been very little studied. However, the manipulation method is not uncommon in our daily lives. We analyze the dynamic behavior of a rigid polygonal part being striked and sliding on a horizontal surface under the action of fiction. There are two parts in this problem; one is the impact problem, and the other is the sliding problem. We characterize the impact and sliding dynamics with friction for polygonal parts, and present the possibility of reverse calculation for motion planning of striking operations. Using a high speed video camera, the computer simulation results are experimentally verified.

• Bulletin of the Korean Chemical Society
• /
• 제15권3호
• /
• pp.241-245
• /
• 1994

A method has been developed to estimate the kinetic energy release originating from the reverse critical energy in unimolecular ion dissociation. Contribution from the excess energy was estimated by RRKM theory, the statistical adiabatic model and the modified phase space calculation. This was subtracted from the experimental kinetic energy release distribution (KERD) via deconvolution. The present method has been applied to the KERDs in $H_2$, loss from $C_6H_6^+$ and HF loss from ${CH_2CF_2}^+$. In the present formalism, not only the energy in the reaction coordinate but also the energy in some transitional vibrational degrees of freedom at the transition state is thought to contribute to the experimental kinetic energy release. Details of the methods for treating the transitional modes are found not to be critical to the final outcome. For a reaction with small excess energy and large reverse critical energy. KERD is shown to be mainly governed by the reverse critical energy.

• Transactions of the Korean Society of Mechanical Engineers
• /
• 제16권7호
• /
• pp.1391-1397
• /
• 1992

Improved power law flow model was suggested for the calculation of wake flow characteristics around the three dimensional ship stern in case of the formation of bilge vortex in the direction of stern. In comparison with the power law and Coles flow model, the flow velocity calculated based on this study was delayed around the boundary of inner layer and outer layer in reverse flow. More accurate results was obtained with this improved power law flow model by the velocity calculation around ship stern. Accuracy was validated with the comparison of other calculation results and experimental datas.

• Proceedings of the Safety Management and Science Conference
• /
• 대한안전경영과학회 2002년도 춘계학술대회
• /
• pp.275-283
• /
• 2002

This study is focused on the calculation for optimum period for environmental logistics system to replace old truck. Companies throughout the world have recognized the importance of environmentalism and the role of logistics in structuring a corporate response to environmental issues like recycling, waste disposal, pollution, and many others. Reverse logistics, the term often used to represent the role of logistics in environmentalism, is gaining acceptance by firms.

• Progress in Superconductivity and Cryogenics
• /
• 제5권2호
• /
• pp.58-65
• /
• 2003

The high temperature superconductivity(HTS) cable must be cooled below the nitrogen liquefaction temperature to applicate the cable in power generation and transmi-ssion system under the superconducting state. To obtain superconducting state. a reliable cryocooler system is required. Structural and thermal design have been performed to design cryocooler system operated with reverse Brayton cycle using gas neon as refrigerant. This cryocooler system consists of compressor. recuperator. coldbox. control valves and has 1 kW cooling capacity. Heat loss calculation was conducted for the given cryocooler system by considering the conduction and radiation through the multi-layer insulation(MLI) and high vacuum. The results can be summarized as: conduction heat loss is 7 W in valves and access port and radiation heat loss is 18 W through the surface of cryocooler. The full design specifications were discussed and the results were applied to construct in house HTS cable cooling system.