• Journal of Korean Neurosurgical Society
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• v.60 no.2
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• pp.181-188
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• 2017

Objective : The objective of this study was to analyze the correlation between further compression and necrotic area in osteoporotic vertebral fracture (OVF) patients with contrast-enhanced magnetic resonance imaging (CEMRI). In addition, we investigated the radiological and clinical outcome according to the range of the necrotic area. Methods : Between 2012 and 2014, the study subjects were 82 OVF patients who did not undergo vertebroplasty or surgical treatment. The fracture areas examined on CEMRI at admission were defined as edematous if enhancement was seen and as necrotic if no enhancement was seen. The correlation between further compression and the necrotic and edematous areas of CEMRI, age, and bone mineral density was examined. Also, necrotic areas were classified into those with less than 25% (non-necrosis group) and those with more than 25% (necrosis group) according to the percentages of the entire vertebral body. For both groups, further compression and the changes in wedge and kyphotic angles were examined at admission and at 1 week, 3 months, and 6 months after admission, while the clinical outcomes were compared using the visual analog scale (VAS) and Eastern Cooperative Oncology Group (ECOG) performance status grade. Results : Further compression was $14.78{\pm}11.11%$ at 1 month and $21.75{\pm}14.43%$ at 6 months. There was a very strong correlation between the necrotic lesion of CEMRI and further compression (r=0.690, p<0.001). The compression of the necrosis group was $33.52{\pm}12.96%$, which was higher than that of the non-necrosis group, $14.96{\pm}10.34%$ (p<0.005). Also, there was a statistically significantly higher number of intervertebral cleft development and surgical treatments being performed in the necrosis group than in the non-necrosis group (p<0.005). Moreover, there was a statistical difference in the decrease in the height of the vertebral body, and an increase was observed in the kyphotic change of wedge angle progression. There was also a difference in the VAS and ECOG performance scales. Conclusion : The necrotic area of CEMRI in OVF had a strong correlation with further compression over time. In addition, with increasing necrosis, intervertebral clefts occurred more frequently, which induced kyphotic changes and resulted in poor clinical outcomes. Therefore, identifying necrotic areas by performing CEMRI on OVF patients would be helpful in determining their prognosis and treatment course.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.4
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• pp.51-56
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• 2011

In this paper, we propose a CAN message compression method using bit rearrangement to reduce the CAN bus load and the error probability during the transmission of CAN messages. In conventional CAN message compression methods, message compression is accomplished by sending only the differences between the previous data and the current data. In the proposed method, the difference bits are rearranged to further increase the compression efficiency. By simulations in car applications, it is shown that the CAN transmission data is further reduced up to 26% by the proposed method, compared with the conventional method.

• Proceedings of the Korea Society of Information Technology Applications Conference
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• 2005.11a
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• pp.169-172
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• 2005

Genetic algorithm based predictor for lossless image compression is propsed. We describe a genetic algorithm to learn predictive model for lossless image compression. The error image can be further compressed using entropy coding such as Huffman coding or arithmetic coding. We show that the proposed algorithm can be feasible to lossless image compression algorithm.

• Geomechanics and Engineering
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• v.18 no.4
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• pp.417-426
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• 2019

Gangue filling in the goaf is an effective measure to control the surface subsidence. However, due to the obvious deformation of gangue compression, the filling effect deserves to be further studied. To this end, the deformation of coal gangue filling in the goaf is analyzed by theoretical analysis, large-scale crushed rock compression test, and field investigation. Through the compression test of crushed rock, the deformation behaviour characteristics and energy dissipation characteristics is obtained and analysed. The influencing factors of gangue filling and predicted amount of main deformation are summarized. Besides, the predicted equation and filling subsidence coefficients of gangue are obtained. The gangue filling effect was monitored by the movement observation of surface rock. Gangue filling can support the roof of the goaf, effectively control the surface subsidence with little influence on the ground villages. The premeter and equations of the main deformation in the gangue filling are verified, and the subsidence coefficient is further reduced by adding cemented material or fine sand. This paper provides a practical and theoretical reference for further development of gangue filling.

• Steel and Composite Structures
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• v.42 no.5
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• pp.617-631
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• 2022

To study the eccentric compressive performance of the basalt-fiber reinforced recycled aggregate concrete (BFRRAC)-filled circular steel tubular stub column, 8 specimens with different replacement ratios of recycled coarse aggregate (RCA), basalt fiber (BF) dosage, strength grade of recycled aggregate concrete (RAC) and eccentricity were tested under eccentric static loading. The failure mode of the specimens was observed, and the relationship curves during the entire loading process were obtained. Further, the load-lateral displacement curve was simulated and verified. The influence of the different parameters on the peak bearing capacity of the specimens was analyzed, and the finite element analysis model was established under eccentric compression. Further, the design-calculation method of the eccentric bearing capacity for the specimens was suggested. It was observed that the strength failure is the ultimate point during the eccentric compression of the BFRRAC-filled circular steel tubular stub column. The shape of the load-lateral deflection curves of all specimens was similar. After the peak load was reached, the lateral deflection in the column was rapidly increased. The peak bearing capacity decreased on enhancing the replacement ratio or eccentric distance, while the core RAC strength exhibited the opposite behavior. The ultimate bearing capacity of the BFRRAC-filled circular steel tubular stub column under eccentric compression calculated based on the limit analysis theory was in good agreement with the experimental values. Further, the finite element model of the eccentric compression of the BFRRAC-filled circular steel tubular stub column could effectively analyze the eccentric mechanical properties.

• Proceedings of the Optical Society of Korea Conference
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• 1991.06a
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• pp.102-108
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• 1991

Utilizing self-phase modulation effects of a dispersion-shifted fiber and delay-line characteristics of two gratings, mode-locked 80 ps pulses at 1.319${\mu}{\textrm}{m}$ wavelength from a Nd: YAG laser are compressed down to 2.1 ps. These pulses are further compressed down to 340 fs using higher order soliton effects in a common single mode fiber.

• MALSORI
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• v.55
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• pp.143-158
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• 2005

The adequate compression algorithm is essential to achieve high quality embedded TTS system. in this paper, we Propose waveform interpolation coder for TTS corpus compression after many speech coder investigation. Unlike speech coders in communication system, compression rate and anality are more important factors in TTS DB compression than other performance criteria. Thus we select waveform interpolation algorithm because it provides good speech quality under high compression rate at the cost of complexity. The implemented coder has bit rate 6kbps with quality degradation 0.47. The performance indicates that the waveform interpolation is adequate for TTS DB compression with some further study.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.12
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• pp.4624-4642
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• 2014

Image compression is a popular research issue that focuses on the problems of reducing the size of multimedia files. Vector Quantization (VQ) is a well-known lossy compression method which can significantly reduce the size of a digital image while maintaining acceptable visual quality. A locally adaptive scheme (LAS) was proposed to improve the compression rate of VQ in 1997. However, a LAS needs extra indicators to indicate the sources, consequently the compression rate of LAS will be affected. In this paper, we propose a novel method to eliminate the LAS indicators and so improve the compression rate. The proposed method uses the concept of data hiding to conceal the indicators, thus further improving the compression rate of LAS. From experimental results, it is clearly demonstrated that the proposed method can actually eliminate the extra indicators while successfully improving the compression rate of the LAS.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.6
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• pp.2761-2781
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• 2018

With the continuous growth of data size and the use of compression technology, data reduction has great research value and practical significance. Aiming at the shortcomings of the existing semantic compression algorithm, this paper is based on the analysis of ItCompress algorithm, and designs a method of bidirectional order selection based on interval partitioning, which named An Optimized Iterative Semantic Compression Algorithm (Optimized ItCompress Algorithm). In order to further improve the speed of the algorithm, we propose a parallel optimization iterative semantic compression algorithm using GPU (POICAG) and an optimized iterative semantic compression algorithm using Spark (DOICAS). A lot of valid experiments are carried out on four kinds of datasets, which fully verified the efficiency of the proposed algorithm.

• Transactions of Materials Processing
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• v.4 no.1
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• pp.39-47
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• 1995

The compression molding of SMC (sheet molding compund) at room temperature was analyzed based on rigid-viscoplastic approach by three dimensional finite element program. The developed program was tested by solving the three dimensional compression of wedge type specimens of aluminum alloys at various processing conditions. The simulation results were compared well to the experimental results available in the literature. based on this comparison the program was proved to be valid and was further applied in solving compression molding of SMC, which is a thermosetting material reinforced with chopped fiber glass. To investigate the effects of friction conditions and mold closing speeds for compression molding of SMC charge at room temperature, compressions of the cylindrical and rectangular shaped SMC were analyzed for various friction conditions and mold closing speeds. The calculated load values were compared to the experimental results for the compression molding of cylindrical specimen.