• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2002년도 Proceedings of International Symposium on Remote Sensing
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• pp.810-814
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• 2002

According to the image level definition for KOMPSAT-2 in KOMPSAT-2 Ground Station Specification, the level 0 is frame formatted, unprocessed data at full resolution; any and all communications artifacts (e.g., synchronization frames, communications headers) removed. The level 0 is used for two purposes: 1) exchange of imagery between image receiving & processing element (IRPE), and 2) image transfer from the Receiving & Archiving Subsystem to Search & Processing Subsystem. On-board processing of imagery data of KOMPSAT-2 includes JPEG-like compression and encryption besides conventional CCSDS packetization. The encryption is used to secure imagery data from any intervention during downlink and compression allows real-time downlink of image data reducing data rate produced from the camera. While developing ground receiving system for KOMPSAT-2, it was necessarily to define level 0 products. In this paper, we will suggest level 0 product definition for KOMPSAT-2 and explain reasons of the decisions made. The key factor used while defining the level 0 products is the efficiency of whole ground receiving system. The latter half of the paper will explain the implementation of software that generates level 0 products. The necessary steps to produce level 0 products will be explained, and the performance achieved will be presented.

• Geomechanics and Engineering
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• 제14권2호
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• pp.115-129
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• 2018

This paper presents a set of results of plate load tests that imposed incremental cyclic loading to a sandy soil bed containing multiple layers of granulated rubber-soil mixture (RSM) at large model scale. Loading and unloading cycles were applied with amplitudes incrementally increasing from 140 to 700 kPa in five steps. A thickness of the RSM layer of approximately 0.4 times the footing diameter was found to deliver the minimum total and residual settlements, irrespective of the level of applied cyclic load. Both the total and residual settlements decrease with increase in the number of RSM layers, regardless of the level of applied cyclic load, but the rate of reduction in both settlements reduces with increase in the number of RSM layers. When the thickness of the RSM layer is smaller, or larger, settlements increase and, at large thicknesses may even exceed those of untreated soil. Layers of the RSM reduced the vertical stress transferred through the foundation depth by distributing the load over a wider area. With the inclusion of RSM layers, the coefficient of elastic uniform compression decreases by a factor of around 3-4. A softer response was obtained when more RSM layers were included beneath the footing damping capacity improves appreciably when the sand bed incorporates RSM layers. Numerical modeling using "FLAC-3D" confirms that multiple RSM layers will improve the performance of a foundation under heavy loading.

• Steel and Composite Structures
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• 제34권2호
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• pp.241-260
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• 2020

This article presented a comprehensive model to study static buckling stability and associated mode-shapes of higher shear deformation theories of sandwich laminated composite beam under the compression of varying axial load function. Four higher order shear deformation beam theories are considered in formulation and analysis. So, the model can consider the influence of both thick and thin beams without needing to shear correction factor. The compression force can be described through axial direction by uniform constant, linear and parabolic distribution functions. The Hamilton's principle is exploited to derive equilibrium governing equations of unified sandwich laminated beams. The governing equilibrium differential equations are transformed to algebraic system of equations by using numerical differential quadrature method (DQM). The system of equations is solved as an eigenvalue problem to get critical buckling loads and their corresponding mode-shapes. The stability of DQM in determining of buckling loads of sandwich structure is performed. The validation studies are achieved and the obtained results are matched with those. Parametric studies are presented to figure out effects of in-plane load type, sandwich thickness, fiber orientation and boundary conditions on buckling loads and mode-shapes. The present model is important in designing process of aircraft, naval structural components, and naval structural when non-uniform in-plane compressive loading is dominated.

• 한국정보통신학회논문지
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• 제12권8호
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• pp.1511-1518
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• 2008

무선 센서 네트워크는 소형의 무선 센서노드들로 구성된 네트워크이다. 무선으로 구성된 센서 네트워크는 사물과 환경의 변화를 감지하여 싱크로 전송한다. 무선 센서 네트워크에서 센서 노드는 무선으로 데이터를 전송할 때 가장 많은 에너지를 소모한다. 한정된 에너지 자원을 효율적으로 사용하기 위해서는 데이터 전송에 이용하는 라디오모듈의 사용을 최소화하여 네트워크 전체의 데이터 전송량을 감소시켜야 한다. 본 논문에서 제안하는 NRMC는 에너지 소모를 줄이기 위해 DPCM, 웨이블릿, 양자화, 가변 길이 부호화를 사용하여 전송되는 데이터의 양을 줄여 라디오모듈을 통한 데이터 전송 횟수를 줄였고, 결과적으로 센서네트워크의 트래픽을 감소시켜 에너지 소모를 줄였다.

• Steel and Composite Structures
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• 제18권2호
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• pp.519-546
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• 2015

This study addresses the load capacity prediction of circular concrete-filled steel tube (CFST) columns under axial compression using current design codes. Design methods given in the Chinese code CECS 28:2012 (2012), American code AISC 360-10 (2010) and EC4 (2004) are presented and described briefly. A wide range of experimental data of 353 CFST columns is used to evaluate the applicability of CECS 28:2012 in calculating the strength of circular CFST columns. AISC 360-10 and EC4 (2004) are also compared with the test results. The comparisons indicate that all three codes give conservative predictions for both short and long CFST columns. The effects of concrete strength, steel strength and diameter-to-thickness ratio on the accuracy of prediction according to CECS 28:2012 are discussed, which indicate a possibility of extending the limitations on the material strengths and diameter-to-thickness ratio to higher values. A revised equation for slenderness reduction factor in CECS 28:2012 is given.

• Computers and Concrete
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• 제22권6호
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• pp.539-550
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• 2018

Concrete is highly non-linear material which is originating from the transition zone in the form of micro-cracks, governs material response under various loadings. In this paper, the constitutive models published by many researchers have been used to generate novel stiffness parameters and constitutive curves for concrete. Following such linear material formulations, where the energy is conservative during the curvature, and a nonlinear contribution to the concrete has been made and investigated. In which, nonlinear concrete elastic modulus modeling has been developed that is capable-of representing concrete elasticity for grades ranging from 10 to 140 MPa. Thus, covering the grades range of concrete up to the ultra-high strength concrete, and replacing many concrete models that are valid for narrow ranges of concrete strength grades. This has been followed by the introduction of the nonlinear Hooke's law for the concrete material through the replacement of the Young constant modulus with the nonlinear modulus. In addition, the concept of concrete elasticity index (${\varphi}$) has been proposed and this factor has been introduced to account for the degradation of concrete stiffness in compression under increased loading as well as the multi-stages micro-cracking behavior of concrete under uniaxial compression. Finally, a sub-routine artificial neural network model has been developed to capture the concrete behavior that has been introduced to facilitate the prediction of concrete properties under increased loading.

• Composites Research
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• 제36권1호
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• pp.42-47
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• 2023

In this paper, we present a fatigue life prediction methodology using multiple S-N curves according to the different stress states of laminated composites. The stress states of the plies of the laminated composites are classified into five modes: longitudinal tension or compression and transverse tension or compression, and shear according to the maximum stress criterion and Puck's criterion with a scaling factor K. This methodology has advantages in computational cost, and it can also consider microstructural characteristics of the composites by applying different S-N curves. The S-N curves for the fatigue analysis are obtained by experimental fatigue test. The proposed methodol is implemented into commercial software, ABAQUS user material subroutine and therefore, the fatigue analysis is conducted using the structural analysis results. The finite element (FE) simulation results are presented for unidirectional composites with and without open-hole. The FE simulation results show that the stress condition is different depending on the fiber orientation of the unidirectional composite, so the fatigue life is calculated with different S-N curves.

• Journal of Korean Neurosurgical Society
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• 제52권4호
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• pp.339-345
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• 2012

Objective : The purpose of this study was to investigate the patterns and the risk factors of newly developed vertebral compression fractures (VCFs) after percutaneous vertebroplasty (PVP). Methods : We performed a retrospective review of the 244 patients treated with PVP from September 2006 to February 2011. Among these patients, we selected 49 patients with newly developed VCFs following PVP as the new VCFs group, and the remaining 195 patients as the no VCFs group. The new VCFs group was further divided into 2 groups : an adjacent fractures group and a nonadjacent fractures group. The following data were collected from the groups : age, gender, body weight/height, body mass index (BMI), bone mineral density (BMD) score of the spine and femur, level of initial fracture, restoration rate of anterior/middle vertebral height, and intradiscal cement leakage, volume of polymethylmethacrylate (PMMA). Results : Age, gender, mean body height/weight, mean BMI and volume of PMMA of each of the group are not statistically significantly associated with fractures. In comparison between the new VCFs group and the no VCFs group, lower BMD, intradiscal cement leakage and anterior vertebral height restoration were the significant predictive factors of the fracture. In addition, new VCFs occurrence at the adjacent spines was statistically significant, when the initial fracture levels were confined to the thoracolumbar junction, among the subgroups of new VCFs. Conclusion : Lower spinal BMD, the greater anterior vertebral height restoration rate and intradiscal cement leakage were confirmed as risk factors for newly formed VCFs after PVP.

• Journal of Pharmaceutical Investigation
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• 제41권2호
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• pp.83-90
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• 2011

Main objectives of this study were to investigate the effects of a lubricant, magnesium stearate, as blended in a hydrophilic matrix tablet and to identify significant factors using a tablet ejection force and a swelling property. The characteristics of tablet ejection were evaluated with three different compression forces (30, 40, and 60 MPa) and two controlled factors, amount of magnesium stearate and its mixing time. A hydrophilic model drug (terazosin HCl dihydrate) was regarded as a default factor. Tablet swelling was also evaluated. The optimal amount of PEG compared to PEO was set to be 88.50% w/w. As the amount of magnesium stearate was varied from 0.79% to 2.20% w/w, the amount of PEO and PEG was adjusted to meet the tablet's total weight while maintaining the ratio between the two excipients constant. As the mixing time of magnesium stearate was increased, the tablet ejection force and the swelling property were decreased. As the amount of magnesium stearate was increased, the tablet ejection force and the swelling property were decreased since the increased mixing time and the amount of magnesium stearate induced hydrophobic properties of the matrix tablet more effectively. The ejection force of the tablet increased as a result of increase in the compression force, which means that the breaking of tablet/die-wall adhesion energy was also increased when the compression energy was increased. The results gavea valuable guide how to choose suitable amount of the lubricant with processing conditions for the development of hydrophilic matrix formulations.

• Journal of Korean Neurosurgical Society
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• 제50권5호
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• pp.434-440
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• 2011

Objective : The goals of surgical intervention for metastatic spinal cord compression (MSCC) are prolonging survival and improving quality of life. Non-ambulatory paraplegic patients, either at presentation or after treatment, have a much shorter life expectancy than ambulatory patients. We therefore analyzed prognostic factors for survival and postoperative ambulation in patients surgically treated for MSCC. Methods : We assessed 103 patients with surgically treated MSCC who presented with lower extremity weakness between January 2001 and December 2008. Factors prognostic for overall survival (OS) and postoperative ambulation, including surgical method, age, sex, primary tumor site, metastatic spinal site, surgical levels, Tokuhashi score, and treatment with chemo- or radiation therapy, were analyzed retrospectively. Results : Median OS was significantly longer in the postoperatively ambulatory group [11.0 months; 95% confidence interval (CI), 9.29-12.71 months] than in the non-ambulatory group (5.0 months; 95% CI, 1.80-8.20 months) ($p$=0.035). When we compared median OS in patients with high (9-11) and low (0-8) Tokuhashi scores, they were significantly longer in the former (15.0 months; 95% CI, 9.29-20.71 months vs. 9.0 months; 95% CI, 7.48-10.52 months; $p$=0.003). Multivariate logistic regression analysis showed that preoperative ambulation with or without aid [odds ratio (OR) 5.35; 95% CI 1.57-18.17; $p$=0.007] and hip flexion power greater than grade III (OR 6.23; 95% CI, 1.29-7.35; $p$=0.038) were prognostic of postoperative ambulation. Conclusion : We found that postoperative ambulation and preoperative high Tokuhashi score were significantly associated with longer patient survival. In addition, preoperative hip flexion power greater than grade III was critical for postoperative ambulation.