• Proceedings of the Korean Operations and Management Science Society Conference
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• 1996.04a
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• pp.147-150
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• 1996

Human posture prediction and motion simulation methods try to solve inverse kinematic problems using the optimization technique based on the concept of minimum principle. It is very important to select a cost function which relfects the human posture acurately. In this study, lifting postures were predicted using the five biomechanical cost functions and compared with real human postures in order to evaluate the predictivities of the cost functions. The result showed that all the biomechanical cost functions used in this study could not predict lifting postures accurately. The cost function which minimizes the sum of joint moments showed the smallest mean prediction error, while the one which minimizes the MUR showed statistically better performance.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.05a
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• pp.75-76
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• 2023

The construction industry's lack of experience and expertise makes it difficult for projects to realize the full benefits of implementing modular construction. Such project performance-hindering elements are often labeled as modular challenges. The added requirement for the transportation of the finished volumetric module is one aspect of the 'module transportation logistics,' the under-researched modular challenge that can prevent projects from incurring maximum cost and productivity benefits. The typical module transportation phases include lifting, transporting, and offloading. From conducting a literature review, this paper aims to investigate the equipment commonly adopted to lift and offload the module and validate its economic efficiency by comparing it with the alternative lifting/offloading equipment used in the two case projects. The results showed that hydraulic jacks are an economic alternative to the crane for lifting/offloading the module. The increase in single-module projects with smaller budgets made crane usage economically undesirable, and this study suggested a viable option for a more economical alternative.

• Journal of Mechanical Science and Technology
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• v.20 no.10
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• pp.1753-1764
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• 2006

A U-80 propeller and its modified version, U-75 propeller, are used for a micro air vehicle. The performance characteristics of a U-80 propeller and a U-75 propeller have not much known in the published literature. Thus, their aerodynamic characteristics are investigated using a lifting surface numerical method. The lifting surface method is validated by comparing computed results with measured data in a wind tunnel. From the computed results, it is found that the U-75 propeller produces larger thrust with higher efficiency than the U-80 propeller. To enhance the performance of these propellers, a new propeller is designed by following the sequential design procedures with the design parameters such as hub-tip ratio, maximum camber and its position, and chord length distribution along the radial direction. The performance of the designed propeller is shown to be improved much comparing with those of both the U-80 and U-75 propellers.

• Journal of Broadcast Engineering
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• v.11 no.2 s.31
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• pp.164-173
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• 2006

The data structure of the concentric mosaic can be regarded as a video sequence with a slowly panning camera. We take a concentric mosaic with match or alignment of video sequences. Also the concentric mosaic required for huge memory. Thus, compressing is essential in order to use the concentric mosaic. Therefore we need the algorithm that compressed data structure was maintained and the scene was decoded. In this paper, we used 3D lifting transform to compress concentric mosaic. Lifting transform has a merit of wavelet transform and reduces computation quantities and memory. Because each frame has high correlation, the complexity which a scene is detected form 3D transformed bitstream is increased. Thus, in order to have higher performance and decrease the complexity of detecting of a scene we executed 3D lifting and then transformed data set was sequently compressed with each frame unit. Each frame has a flexible bit rate. Also, we proposed the algorithm that compressed data structure was maintained and the scene was decoded by using property of lifting structure.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.5C
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• pp.344-354
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• 2005

In this paper, we proposed a new lifting architecture for JPEG2000 and implemented to ASIC. We proposed a new cell to execute unit calculation of lifting using the property of lifting which is the repetitious arithmetic with same structure, and then recomposed the whole lifting by expanding it. After the operational sequence of lifting arithmetic was analyzed in detail and the causality was imposed for implementation to hardware, the unit cell was optimized. A new lifting kernel was organized by expanding simply the unit cell, and a lifting processor was implemented for Motion JPEG2000 using it. The implemented lifting kernel can accommodate the tile size of $1024{\times}1024$, and support both lossy compression using the (9,7) filter and lossless compression using (5,3) filter. Also, it has the same output rate as input rate, and can continuously output the wavelet coefficients of 4 types(LL, LH, HL, HH) at the same time. The implemented lifting processor completed a course of ASIC using $0.35{\mu}m$ CMOS library of SAMSUNG. It occupied about 90,000 gates, and stably operated in about 150MHz though difference from the used macro cell for the multiplier. Finally, the improved operated in about 150MHz though difference from the used macro cell for the multiplier. Finally, the performance can be identified in comparison with the previous researches and commercial IPs.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.7C
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• pp.647-657
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• 2005

In this paper, we proposed a new lifting architecture for JPEG2000 and implemented to ASIC. We proposed a new cell to execute unit calculation of lifting using the property of lifting which is the repetitious arithmetic with same structure, and then recomposed the whole lifting by expanding it. After the operational sequence of lifting arithmetic was analyzed in detail and the causality was imposed for implementation to hardware, the unit cell was optimized. A new lifting kernel was organized by expanding simply the unit cell, and a lifting processor was implemented for Motion JPEG2000 using it. The implemented lifting kernel can accommodate the tile size of 1024$\times$1024, and support both lossy compression using the (9,7) filter and lossless compression using (5,3) filter. Also, it has the same output rate as input rate, and can continuously output the wavelet coefficients of 4 types(LL, LH, HL, HH) at the same time. The implemented lifting processor completed a course of ASIC using 0.35$\mu$m CMOS library of SAMSUNG. It occupied about 90,000 gates, and stably operated in about 150MHz though difference from the used macro cell for the multiplier. Finally, the improved operated in about 150MHz though difference from the used macro cell for the multiplier. Finally, the performance can be identified in comparison with the previous researches and commercial IPs.

• Korean Journal of Construction Engineering and Management
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• v.9 no.3
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• pp.185-193
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• 2008

In order to improve work efficiency in high-rise apartment building construction, it is required to establish the major criteria and practical method for selecting the construction lifts. It is necessary to analyze work efficiency and economic feasibility depending on speed, size and capacity of lifting equipment and characteristics of construction projects. The purpose of this research is to develop the fundamental process and information for selecting the lift in order to plan and manage the material lifting and laborers' vertical transporting in the high-rise apartment building projects more effectively. In order to satisfy the objective of the research, work performance of the lifting machines with different speed and carrying capacity is analyzed under the practical constraints. In addition, potential economic evaluation is conducted. One of the significant findings of the research is that the mid-speed lift shows 43% improvement in work efficiency compared with the low-speed lift. The results of the research will be used as the basis for developing the further optimal lifting management system.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.1
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• pp.37-43
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• 2023

Compressed still image or video bitstreams require protection from channel errors in a wireless channel. Embedded Zerotree Coding(EZW), SPIHT could have provided unprecedented high performance in image compression with low complexity. If bit error is generated by dint of wireless channel transmission problem, the loss of synchronization on between encoder and decoder causes serious performance degradation. But wavelet zerotree coding algorithms are producing variable-length codewords, extremely sensitive to bit errors. The idea is to partition the lifting coefficients. A many partition of lifting transform coefficients distributes channel error from wireless channel to each partition. Therefore synchronization problem that caused quality deterioration in still image and video stream was improved.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.01a
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• pp.7-12
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• 2009

In JPEG2000, the Cohen-Daubechies-Feauveau (CDF) 9/7-tap wavelet filter adopted in lossy compression is implemented by the lifting scheme or by the convolution scheme while the LeGall 5/3-tap wavelet filter adopted in lossless compression is implemented just by the lifting scheme. However, these filters are not optimal in terms of Peak Signal-to-Noise Ratio (PSNR) values, and irrational coefficients of wavelet filters are complicated. In this paper, we proposed a method to optimize image quality based on wavelet filter design and on wavelet decomposition. First, we propose a design of wavelet filters by selecting the most appropriate rational coefficients of wavelet filters. These filters are shown to have better performance than previous wavelet ones. Then, we choose the most appropriate wavelet decomposition to get the optimal PSNR values of images.

• Journal of Mechanical Science and Technology
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• v.20 no.10
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• pp.1548-1556
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• 2006

Appropriate contact force is required for the pantograph on the high speed train to collect current from the catenery system without separation. However, at high speed, large aerodynamic lifting force is generated by the contact plate and the body of pantograph, which may cause wear of the contact wire. In this study, to confirm the interface performance of the pantograph on Korea High Speed Train, a method to measure the contact force of the pantograph was proposed and the related measuring system was developed. The forces acting on the pantograph were clarified and a practical procedure to estimate the forces was proposed. A special device was invented and applied to measure the aerodynamic lifting force. Measured contact forces were displayed by the developed system and evaluated based on the criteria.