• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.10
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• pp.1462-1470
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• 1989

This paper aims at investigating the Demand Assigned Multiple Access(DAMA) system for the packet-switched Satellite Communication. An onboard processor of the multisport beam satellite incorporates the ground controller to macimize the packet transmissions for each slot. 'Request Following' trnasmission mode is introduced as a transmission strategy of ground station under the control of its zone controller. The combined scheme of reservation channel access and contention channel access was proposed by Lee & Mark[3] for improving the Delay-Throughput performance. Our scheme provides less communication delay of approximately max. 200msec for achieving the corresponding throughput than the Lee & Mark's work does. Delay versus Throughput curves as well as Delay versus Traffic parameter curves are obtained. Numerical results obtained through the analysis and by the computer simulation show that the proposed scheme provides the low average packer delay even under the condition that the number of transponders (M)is below the half of the number of zones(N).

• The Journal of Engineering Geology
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• v.17 no.3
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• pp.393-404
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• 2007

The purpose of this study is to capture the essentials in survey and evaluation scheme which are able to assess the hazard of a rock slope systematically. Statistical analysis are performed on slope instability parameters related to failure of the rock slope. As the slope instability parameters, twelve survey items are considered such as tension crack, surface deformation, deformation of retaining structures, volume of existing failures, angles between strike of discontinuity and strike of cut slope face, angles between dip of discontinuity and dip of cut slope face, discontinuity condition, cut slope angle, rainfall or ground water level, excavation condition, drainage condition, reinforcement. A total of 233 road cut slopes located in Gyeongnam were considered. The stability of the road cut slopes were evaluated by estimating the slope instability index(SII) and corresponding stability rank. 126 rock slopes were selected to analyze statistical relation between SII and slope instability parameters. The multiple regression analysis was applied to derive statistical models which are able to predict the SII and corresponding slope stability rank. Also, its applicability was explored to predict the slope failures using the variables of slope instability parameters. The results obtained in this study clearly show that the methodology given in this paper have strong capabilities to evaluate the failures of the road cut slope effectively.

• International Journal of Automotive Technology
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• v.7 no.1
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• pp.43-49
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• 2006

In this paper, an index for the evaluation of a vehicle intake booming noise and intake sound quality were developed through a correlation analysis and a multiple factor regression analysis of objective measurement and subjective evaluation data. At first, an intake orifice noise was measured at the wide-open throttle test condition. And then, an acoustic transfer function between intake orifice noise and interior noise at the steady state condition was estimated. Simultaneously, subjective evaluation was carried out with a 10-scale score by 8 intake noise and vibration expert evaluators. Next, the correlation analysis between the psychoacoustic parameters derived from the measured data and the subjective evaluation was performed. The most critical factor was determined and the corresponding index for intake booming noise and sound quality are obtained from the multiple factor regression method. And, the optimal design of intake system was studied using the booming noise and the sound quality evaluation index for expectation performance of intake system. Conclusively, the optimal designing parameters of intake system from noise level and sound quality whose point of view were extracted by adapting comparative weighting between the booming noise and sound quality evaluation index, which optimized the process. These work could be represented guideline to system engineers, designers and test engineers about optimization procedure of system performance by considering both of noise level and sound quality.

• Journal of radiological science and technology
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• v.45 no.4
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• pp.355-363
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• 2022

This study was to investigate the prevalence rate of musculoskeletal disorders in relation to general characteristic factors, living environment factors, and work environment factors for sonographer's. For the response questions, the guidelines for musculoskeletal burden work were used. For statistical analysis, SPSS 26.0 version was used. For the common body parts of the sonographer's who responded, the prevalence was investigated by dividing the group into a group with high pain or discomfort and a group with low pain or discomfort according to the degree to which they experienced symptoms during the past 12 months. Multiple logistic regression analysis was used to determine the variance inflation factor(VIF), odds ratio (OR) and corresponding 95% confidence interval (CI). A p-value of <0.05 was considered statistically significant. As a result, housework hours, examination history, regular physical activity, number of patient examinations per day, and sitting posture were investigated as variables for rate musculoskeletal disorders. The sonographer's occupational group was found to have a high prevalence rate of musculoskeletal disorders like various other occupational groups. Based on the results of this study, it is judged that musculoskeletal disorders can be reduced by recognizing musculoskeletal disorders and improving work environment factors.

• Journal of the Korean Geotechnical Society
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• v.29 no.9
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• pp.71-80
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• 2013

This work studies the reliability analysis of a slope that considers multiple failure modes. The analysis consists of two parts. First, significant failure modes that contribute most to system reliability are determined. The so-called barrier method proposed by Der Kiureghian and Dakessian to identify significant failure modes successively is employed. Second, the failure probability for the slope is estimated on the basis of the identified significant failure modes and corresponding design points. For reliability problems entailing multiple design points, failure probability can be estimated by the multi-point first-order reliability method (FORM), Ditlevsen's bounds method, and Monte Carlo simulation. In this paper, a comparative study between these methods has been made through example problems. Analysis results showed that while a soil slope may have a large number of potential slip surfaces, its system failure probability is usually governed by a few significant slip surfaces. Therefore, the most important step in the system reliability analysis for a soil slope is to identify all the significant failure modes in an efficient way.

• International conference on construction engineering and project management
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• 2007.03a
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• pp.450-458
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• 2007

This paper presents the results of a statistical analysis and its research findings focusing on the learning aspect in the process of international joint ventures (IJVs). The contents of this paper is derived from a sample of 96 field cases based on a proposed conceptual model of effective learning for international construction joint ventures (ICJVs). The paper presents a brief review on the conceptual model with hypotheses and summarized the key results of statistical analysis including factor and multiple regression analysis for the testing of the validity of the proposed conceptual model and its associated research hypotheses. Among other research findings, the research confirms that ICJVs provides an excellent platform of in-action learning for construction organization and suggests that good outcomes in learning could be reaped by a company who has a clear learning intent from the beginning and subsequently take corresponding learning actions during the full process of the joint venture.

• Near Infrared Analysis
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• v.1 no.1
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• pp.1-7
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• 2000

A convenient algorithm for optimizing wavelength selection in multiple linear regression (MLR) has been developed. MOP (MLP Optimization Program) has been developed to test all possible MLR calibration models in a given spectral range and finally find an optimal MLR model with external validation capability. MOP generates all calibration models from all possible combinations of wavelength, and simultaneously calculates SEC (Standard Error of Calibration) and SEV (Standard Error of Validation) by predicting samples in a validation data set. Finally, with determined SEC and SEV, it calculates another parameter called SAD (Sum of SEC, SEV, and Absolute Difference between SEC and SEV: sum(SEC+SEV+Abs(SEC-SEV)). SAD is an useful parameter to find an optimal calibration model without over-fitting by simultaneously evaluating SEC, SEV, and difference of error between calibration and validation. The calibration model corresponding to the smallest SAD value is chosen as an optimum because the errors in both calibration and validation are minimal as well as similar in scale. To evaluate the capability of MOP, the determination of benzene content in unleaded gasoline has been examined. MOP successfully found the optimal calibration model and showed the better calibration and independent prediction performance compared to conventional MLR calibration.

• Structural Engineering and Mechanics
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• v.21 no.3
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• pp.351-367
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• 2005

Multi-span beams carrying multiple point masses are widely used in engineering applications, but the literature for free vibration analysis of such structural systems is much less than that of single-span beams. The complexity of analytical expressions should be one of the main reasons for the last phenomenon. The purpose of this paper is to utilize the numerical assembly method (NAM) to determine the exact natural frequencies and mode shapes of a multi-span uniform beam carrying multiple point masses. First, the coefficient matrices for an intermediate pinned support, an intermediate point mass, left-end support and right-end support of a uniform beam are derived. Next, the overall coefficient matrix for the whole structural system is obtained using the numerical assembly technique of the finite element method. Finally, the natural frequencies and the associated mode shapes of the vibrating system are determined by equating the determinant of the last overall coefficient matrix to zero and substituting the corresponding values of integration constants into the related eigenfunctions respectively. The effects of in-span pinned supports and point masses on the free vibration characteristics of the beam are also studied.

• Journal of Microbiology
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• v.40 no.4
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• pp.282-288
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• 2002

Since culture of Helicobacter pylori is relatively insensitive and cumbersome, molecular detection and typing of H. pylori isolates are gaining importance for strain differentiation. In the present study genomic DNA of 42 gastric biopsies and H. pylori isolates from corresponding patients were analyzed and compared by PCR-based RFLP assay. The 1,132-bp product representing an internal portion of ureC gene of H. pylori was amplified by PCR and digested with restriction enzymes HindⅢ, AiuⅠ and PvuⅠ. The HindⅢ, AluⅠ and PvuⅠ digestion produced 4, 7, and 2 distinguishable RFLP patterns respectively from 42-H. pylori isolates. By combining all three restriction enzyme digestions, 15 RFLP patterns were observed. However, when PCR products from 42 gastric biopsy specimens were digested by restriction enzymes HindⅢ, AluⅠ and PvuⅠ, we observed 5, 8 and 2 RFLP patterns, respectively. Patterns from 34 of 42 gastric biopsy specimens matched those of corresponding H. pylori isolates from respective patients. Patterns from the remaining eight biopsy specimens differed and appeared to represent infection with two H. pylori strains. The patterns of one strain from each of these biopsies was identical to that of the isolate from corresponding patients and the second pattern presumably represented the co-infecting strain. From the study, it appears that PCR-based RFLP analysis is a useful primary tool to detect and is distinguish H. pylori strains from gastric biopsy specimens and is superior to culture techniques in the diagnosis of infection with multiple strains of H. pylori.

• Geomechanics and Engineering
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• v.15 no.5
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• pp.1039-1046
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• 2018

This paper presents a limit analysis of the series of construction stages of shallow tunneling method by investigating their respective safety factors and failure mechanisms. A case study for one particular cross-section of Beijing Subway Line 7 is undertaken, with a focus on the effects of multiple soil layers and construction sequencing of dual tunnels. Results show that using the step-excavation technique can render a higher safety factor for the excavation of a tunnel compared to the entire cross-section being excavated all at once. The failure mechanisms for each different construction stage are discussed and corresponding key locations are suggested to monitor the safety during tunneling. Simultaneous excavation of dual tunnels in the same cross-section should be expressly avoided considering their potential negative interactions. The normal and shear forces as well as bending moment of the primary lining and locking anchor pipe are found to reach their maximum value at Stage 6, before closure of the primary lining. Designing these struts should consider the effects of different construction stages of shallow tunneling method.