• Journal of Korean Neurosurgical Society
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• 제48권6호
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• pp.490-495
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• 2010

Objective : Bone cement augmentation procedures such as percutaneous vertebroplasty and balloon kyphoplasty have been shown to be effective treatment for acute or subacute osteoporotic vertebral compression fractures. The purpose of this study was to determine the efficacy of bone cement augmentation procedures for long standing osteoporotic vertebral compression fracture with late vertebral collapse and persistent back pain. Methods : Among 278 single level osteoporotic vertebral compression fractures that were treated by vertebral augmentation procedures at our institute, 18 consecutive patients were included in this study. Study inclusion was limited to initially, minimal compression fractures, but showing a poor prognosis due to late vertebral collapse, intravertebral vacuum clefts and continuous back pain despite conservative treatment for more than one year. The subjects included three men and 15 women. The mean age was 70.7 with a range from 64 to 85 years of age. After postural reduction for two days, bone cement augmentation procedures following intraoperative pressure reduction were performed. Imaging and clinical findings, including the level of the vertebra involved, vertebral height restoration, injected cement volume, local kyphosis, clinical outcome and complications were analyzed. Results : The mean follow-up period after bone cement augmentation procedures was 14.3 months (range 12-27 months). The mean injected cement volume was 4.1 mL (range 2.4-5.9 mL). The unipedicular approach was possible in 15 patients. The mean pain score (visual analogue scale) prior to surgery was 7.1, which decreased to 3.1 at 7 days after the procedure. The pain relief was maintained at the final follow up. The kyphotic angle improved significantly from $21.2{\pm}4.9^{\circ}$ before surgery to $10.4{\pm}3.8^{\circ}$ after surgery. The fraction of vertebral height increased from 30% to 60% after bone cement augmentation, and the restored vertebral height was maintained at the final follow up. There were no serious complications related to cement leakage. Conclusion : In the management of even long-standing osteoporotic vertebral compression fracture for over one year, bone cement augmentation procedures following postural reduction were considered safe and effective treatment in cases of non-healing evidence.

• Steel and Composite Structures
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• 제47권1호
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• pp.121-134
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• 2023

This paper tested 11 concrete-encased concrete-filled steel tube (CFST) composite columns and one reinforced concrete column under combined axial compression and lateral loads. The primary parameters, including the loading system, axial compression ratio, volume stirrup ratio, diameter-to-thickness ratio of the steel tube, and stirrup form, were varied. The influence of the parameters on the failure mode, strength, ductility, energy dissipation, strength degradation, and damage evolution of the composite columns were revealed. Moreover, a two-parameter nonlinear seismic damage model for composite columns was established, which can reflect the degree and development process of the seismic damage. In addition, the relationships among the inter-story drift ratio, damage index and seismic performance level of composite columns were established to provide a theoretical basis for seismic performance design and damage assessments.

• 대한치과교정학회지
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• 제16권2호
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• pp.53-67
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• 1986

The physical tooth movement by orthodontic force is based upon alveolar bone resorption at compression site and new bone formation at tension site of the alveolar socket. The function of the cyclic AMP is to participate not only in initial action of bone cells by mechanical forces but also in the continuous cellular response leading to bone remodelling. This experiment was performed to clarify the role of cyclic AMP in bone remodelling by mechanical force in the NORMAL group, the DIABETES group and the INSULIN TREATED group. The 72 rats were divided into the NORMAL group, the DIABETES group and the INSULIN TREATED group. The same orthodontic forces were applied to the rats of 3 groups. These rats were treated for periods of time ranging from 1 hour, 1 day, 7 days, 14 days, 21 days and 28 days. The samples of alveolar bones were obtained from compression and tension sites surrounding the tipping teeth from NORMAL, DIABETE and INSULIN TREATED rats. The samples were assayed for cyclic AMP by the cyclic AMP RIA kit. The results were as follows: 1. The cyclic AMP levels of alveolar bone in compression and tension sites showed initial decrease, then increased and .remained elevated by the time consuming. 2. The highest cyclic AMP level showed in the DIABETES group and the lowest level was in the NORMAL group. 3. The cyclic AMP levels in the INSULIN TREATED group was similar with the NORMAL group in control and tension sites, but in the compression sites it was similar with the DIABETES group.

• 한국정보통신학회논문지
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• 제11권6호
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• pp.1104-1114
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• 2007

디지털 비디오 압축 기술은 대역폭과 저장 공간이 제한되는 멀티미디어 데이터의 효율적인 전송과 저장을 가능하게 하는 중요한 역할을 해왔다. JVT가 제안한 새로운 비디오 코딩 표준인 H.264/AVC는 압축 성능에 있어서 이전의 표준들을 훨씬 능가하고 있다. 특히 비디오 및 이미지 압축 응용에서 가변길이 부호는 중요한 역할을 한다. H.264/AVC 표준은 엔트로피 코딩 방식으로서 CAVLC를 채택하였다. H.264/AVC의 CAVLC는 많은 메모리 액세스를 필요로 한다. 이는 메모리 액세스시에 상당한 전력을 소비하기 때문에 DMB와 비디오 폰 서비스와 같은 응용을 위해서는 심각한 문제가 될 수 있다. 본 논문에서는 이러한 문제점을 극복하기 위해, 산술연산에 근거한 메모리 사용없는 coeff_token, level 및 run_before 디코딩을 구현하고, total_zero 가변길이 디코딩시에만 필요한 메모리의 70%만 사용하여 구현하는 가변길이 디코딩 기법을 제안한다.

• 소프트웨어공학소사이어티 논문지
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• 제26권1호
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• pp.1-16
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• 2013

가변 길이 정보 메시지는 컴퓨터 네트워크 시스템을 통하여 효율적인 정보 제공을 하기 위하여 개발된 통신 프로토콜 표준이다. 이러한 가변 길이 정보 메시지는 정보 수신자의 정보 요구 수준 및 정보 수신자의 정보 접근 수준에 따라 정보의 상세함을 가변적으로 조절 할 수 있도록 설계된 메시지이다. 정보 메시지 최적화 기술은 정보 메시지를 다양한 데이터 압축 기술을 사용하여, 메시지 전체의 물리적인 사이즈를 줄이려고 노력하였다. 정보 메시지 최적화에서는 정보의 정확성을 최우선으로 고려하고 있어, 최적화 전/후가 동일한 비손실 압축 기법을 응용하여 사용하고 있다. 하지만, 이러한 비손실 압축 기법만을 사용하면, 압축효율성이 현저하게 떨어져, 제한된 대역폭을 갖는 무선 네트워크 환경에서의 효율적인 전송이 이루어지지 않는다. 본 논문에서는 가변 길이 정보 메시지를 대상으로, 메시지 필드 단위로 정보의 최적화를 수행하여 메시지의 길이를 물리적으로 좀 더 효과적으로 최적화하도록 시도하였다. 또한, 본 논문에서 제시한 최적화 방법의 효율성을 보이기 위하여, 가변 길이 정보 메시지에 대한 최적화 실험을 수행하였다.

• Structural Engineering and Mechanics
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• 제6권7호
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• pp.827-839
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• 1998

This paper presents a study of buckling of the multi-vaulted cylindrical shell ("Aster"), under an axial compression alone or combined with an external pressure. This shell which was presented in a recent paper is a self-stiffened structure having a satisfactory behaviour and a higher buckling strength under external pressure than a circular cylindrical shell with the same dimensions. The results of this study emphasize the interest of the behaviour of the "Aster" shell under two other types of loading, revealing an acceptable level of strength which is favorable for an expansion of its use in other areas.

• 한국멀티미디어학회논문지
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• 제20권3호
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• pp.446-455
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• 2017

A color image compression based on saliency map was proposed. The proposed method provides higher quality in saliency blocks on which people's attention focuses, compared with non-saliency blocks on which the attention less focuses at a given bitrate. The proposed method uses 3 different quantization tables according to each block's saliency level. In the experiment using 6 typical images, we compared the proposed method with JPEG and other conventional methods. As the result, it showed that the proposed method (Qup=0.5*Qx) is about 3.1 to 1.2 dB better than JPEG and others in saliency blocks in PSNR at the almost similar bitrate. In the comparison of result images, the proposed one also showed less error than others in saliency blocks.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2008년도 추계 학술논문 발표대회
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• pp.93-96
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• 2008

This research performed strength improvement analysis after evaluating strength characteristics by estimated temperatures to evaluate the real time strength performance of 50 to 80 MPa high performance concrete equipped with heat resistance, and the results are as follows. The lesser W/B and the lesser target slump flow value difference, compression strength was shown to increase, and the more curing temperature becomes, the strength increased accordingly. According to the correlation review result of strength improvement analysis by estimated temperature change performed using logistic analysis model, the compression strength value predicted with logistic curve expression and the compression strength value measured in experiment were shown to have similar correlation, and the strength improvement analysis value by logistic model was shown to be estimated good when W/B is high.

• 전기학회논문지
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• 제56권12호
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• pp.2251-2256
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• 2007

In this paper, the wavelet transform based lossless image compression algorithm is proposed. The proposed algorithm transforms the input image using 9/7 ICFB and S+P filter, and eliminates the spacious correlation of the subband coefficients, applying the context modeling predictive technique based on the multi-resolution structure and the feedback of the prediction error. The prediction context exploits the subordination and direction property of the different level subband in the vertical, horizontal, and diagonal subband coefficients. The simulation result of the high frequency images such as PEPPERS, BOAT, and AIRPLANE shows that the proposed algorithm efficiently predicts the edge area of each multi-resolution subband.

• 한국포장학회지
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• 제7권1호
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• pp.16-20
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• 2001

In order to optimize designing process of corrugated fiberboard boxes for agricultural products, first of all, compression strength of each liner were experimentally evaluated on the various conditions of relative humidity and analyzed by liner regression analysis. At the 66 percents of relative humidity, IK(imported kraft liner) liner board lost little of its compression strength compared to others. At the relative humidity 93 percents, KA liner board lost its compression strength only 40 percents while SK liner board lost up to 56 percents. From the result of prediction modeling of ring crush strength in various humidity conditions, R square values were ranged from 0.59 to 0.97. At 56 percents of RH or below, R square values were relatively low, but at 66 percents of RH or higher, the values were 0.85 or higher. The significance values were lower than 0.001 at every RH condition. Level of significance of experimented values was about 80 percents of predicted values and R square values were between 0.89 to 0.95.