• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제8권11호
• /
• pp.3789-3809
• /
• 2014

Radio environment maps (REMs) and geolocation database represent an important source of information for the operation of cognitive radio networks, replacing or complementing spectrum sensing information. This paper provides a survey of methods for constructing the radio frequency layer of radio environment map (RF-REM) using distributed measurements of the signal levels at a given frequency in space and time. The signal level measurements can be obtained from fixed or mobile devices capable of sensing radio environment and sending this information to the REM. The signal measurements are complemented with information already stored in different REM content layers. The combined information is applied for estimation of the RF-REM layer. The RF-REM construction methods are compared, and their advantages and disadvantages with respect to the spatial distribution of signal measurements and computational complexity is given. This survey also indicates possible directions of further research in indirect RF-REM construction methods. It emphasizes that accurate RF-REM construction methods should in the best case support operation with random and clustered signal measurements, their operation should not be affected by measurements outliers, and it must estimate signal levels comparably on all RF-REM locations with moderate computational effort.

• 대한조선학회논문집
• /
• 제52권3호
• /
• pp.187-197
• /
• 2015

This study aims the development of a semi-analytic method for the parametric roll of large containerships advancing in longitudinal waves. A 1.5 Degree-of-Freedom(DOF) model is proposed to account the change of transverse stability induced by wave elevations and vertical motions (heave and pitch). By approximating the nonlinearity of restoring moment at large heel angles, the magnitude of roll amplitude is predicted as well as susceptibility check for parametric roll occurrence. In order to increase the accuracy of the prediction, the relationship between righting arm(GZ) and metacentric height(GM) is examined in the presence of incident waves, and then a new formula is proposed. Based on the linear approximation of the mean and first harmonic component of GM, the equation of parametric roll in irregular wave excitations is introduced, and the computational results of the proposed model are validated by comparing those of weakly nonlinear simulation based on an impulse-response-function method combined with strip theory. The present semi-analytic doesn’ t require heavy computational effort, so that it is very efficient particularly when numerous sea conditions for the analysis of parametric roll should be considered.

• International Journal of Control, Automation, and Systems
• /
• 제6권2호
• /
• pp.269-277
• /
• 2008

This paper proposes a necessary and sufficient condition of convergence in the $L_2$-norm sense for a feedback-based iterative learning control (ILC) system including a multi-input multi-output (MIMO) linear time-invariant (LTI) plant. It is shown that the convergence conditions for a nominal plant and an uncertain plant are equal to the nominal performance condition and the robust performance condition in the feedback control theory, respectively. Moreover, no additional effort is required to design an iterative learning controller because the performance weighting matrix is used as an iterative learning controller. By proving that the least upper bound of the $L_2$-norm of the remaining tracking error is less than that of the initial tracking error, this paper shows that the iterative learning controller combined with the feedback controller is more effective to reduce the tracking error than only the feedback controller. The validity of the proposed method is verified through computer simulations.

• 수산경영론집
• /
• 제35권1호
• /
• pp.1-22
• /
• 2004

Since the red grouper stock was initially declared to be overfished by the NMFS in September 2002, the Gulf of Mexico Fishery Management Council must prepare for the red grouper rebuilding plan considering the following alternative management policies: Total Allowable Catch(TAC), 5 - month season closure, 1800 - pound trip limit, and 50 - fathom longline boundary. The first concern the Council has is to evaluate the effects of recommended policies and the second is to analyze the impact of management policies on yellow edge grouper. This is because the fleets harvest red grouper also catch yellowedge grouper, the regulations on red grouper are likely to allow fishing effort to be distributed into yellowedge grouper. Therefore, this study is aimed at evaluating the biological and economic effects of management policies considering simultaneously the impact of red grouper regulations on yellow edge grouper by developing a combined red grouper and yellowedge grouper bioeconomic model. The overall results indicate that management policies for red grouper would adversely affect the yellowedge grouper stock if yellowedge grouper is not protected by its regulations. The TAC policy has the most serious impact on the yellowedge grouper stock, while the 1800 - pound trip limit policy minimizes the reduction in the yellowedge grouper stock. However, the target stock size of red grouper is achieved as well as the largest net present value of returns is gained in the TAC policy.

• 보건교육건강증진학회지
• /
• 제29권4호
• /
• pp.83-99
• /
• 2012

Objectives: The purpose of this review is to introduce reporting guidelines for health promotion research in an effort to enhance systematic structure and quality of health promotion research reported in academic papers. Methods: Widely accepted guidelines were selected for description, which focus on 4 distinct types of research design. Checklists and flow diagrams are described and compared. Results: CONSORT Statement is reporting guidelines for randomized controlled trials with a 25-item checklist and a flow diagram. TREND Statement with a 22-item checklist is to guide reporting of health research in nonrandomized design. STROBE Statement is a compiled guidelines for observational health research, accompanied by a 22-item checklist in a combined edition. PRISMA Statement consists of a 27-item checklist and a flow diagram, providing guidelines for reporting systematic reviews and meta-analyses. All items on the checklists and flow diagrams were introduced and discussed. Conclusion: Solid understanding of research designs and adoption of reporting guidelines will enhance the quality of research with information on internal and external validity. Education and training of researchers on the research reporting is required along with systems level adoption of efforts for research enhancement.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2000년도 추계학술대회논문집
• /
• pp.431-436
• /
• 2000

Adaptive feed forward control algorithms based largely upon LMS approach have developed in recent two decades, and they have been widely applied to practical sound and vibration control problems in the case of the reference signal is available. Feedforward control can be applied only when reference signals can be measured or regenerated, while feedback controllers are used to reduce; sound and vibration when reference signals are not available. In recent years, hybrid control schemes in which adaptive feed forward controllers are combined with feedback ones have been studied based on simulations and experiments. The results have shown that the hybrid control may have better control performances in convergence speed and steady state error than the single control schemes. Hybrid control has the advantages of improving stability and performance as well as the disturbance rejection property. However, little effort has been made to the analysis or interpretation of hybrid control systems. In this study, we discussed the feedback controller effects on the stability of feed forward control algorithm in the presence of uncertain error path and a simple example showed that a stable feedback controller could make the feedforward controller unstable. A design criterion of feedback controllers is proposed in order to guarantee the stability of feedforward algorithms in the presence of error paths with uncertainties.

• The Journal of Asian Finance, Economics and Business
• /
• 제6권2호
• /
• pp.173-181
• /
• 2019

The paper aims to evaluate the combination of strategies that influence the success of New Technology Based Firms (NTBFs) located in isolated areas with resource constraints. We utilize the Kauffman Firm Survey to construct a subset of 224 firms operating in primary metal manufacturing industries and who are located in non-thriving areas. We focus on the impact of technological strategy, in the form of Inward Technology Licensing (ITL), combined with financial strategy, in the form of increased financial slack. Using a negative binomial-specification technique to model these relations, we find that ITL positively impacts internal innovation in the firm and this relation is strengthened by the presence of greater financial slack. This positive impact of financial slack supports the behavioral theory of the firm rather than agency theory in that financial slack enables further innovation rather than stifling it. This research confirms the importance of resource acquisition, suggesting that entrepreneurs may utilize external sources of knowledge in an effort to build a favorable situation when facing the challenges of location. Finally, by presenting evidence showing the compatibility of a financial strategy with a knowledge strategy (ITL), this study emphasizes the importance to entrepreneurs of choosing the proper combination of varying strategies.

• Earthquakes and Structures
• /
• 제17권5호
• /
• pp.477-487
• /
• 2019

Understanding the behavior of skew bridges under the action of earthquakes is quite challenging due to the combined transverse and longitudinal responses even under unidirectional hit. The main goal of this research is to assess the response of skew bridges when subjected to longitudinal and transversal earthquake loading. The effect of skew on the response considering two- and three- span bridges with skew angles varying from 0 to 60 degrees is illustrated. Various pier fixities (and hence stiffness) and cross-section shapes, as well as different abutment's bearing articulations, are also studied. Finite-element models are established for modal and seismic analyses. Around 900 models are analyzed under the action of the code design response spectrum. $Vis-{\grave{a}}-vis$ modal properties, the higher the skew angle, the less the fundamental period. In addition, it is found that bridges with skew angles less than 30 degrees can be treated as straight bridges for the purpose of calculating modal mass participation factors. Other monitored results are bearings' reactions at abutments, shear and torsion demand in piers, as well as deck longitudinal displacement. Unlike straight bridges, it has been typically noted that skew bridges experience non-negligible torsion and bi-directional pier base shears. In a complementary effort to assess the accuracy of the conducted response spectrum analysis, a series of time-history analyses are applied under seven actual earthquake records scaled to match the code design response spectrum and critical comparisons are performed.

• Interaction and multiscale mechanics
• /
• 제4권1호
• /
• pp.17-34
• /
• 2011

This paper deals with the modeling of the plane frame structure-foundation-soil system. The superstructure along with the foundation beam is idealized as beam bending elements. The soil medium near the foundation beam with stress concentrated is idealized by isoparametric finite elements, and infinite elements are used to represent the far field of the soil media. This paper presents the modeling of shear wall structure-foundation and soil system using the optimal membrane triangular, super and conventional finite elements. Particularly, an alternative formulation is presented for the optimal triangular elements aimed at reducing the programming effort and computational cost. The proposed model is applied to a plane frame-combined footing-soil system. It is shown that the total settlement obtained from the non-linear interactive analysis is about 1.3 to 1.4 times that of the non-interactive analysis. Furthermore, the proposed model was found to be efficient in simulating the shear wall-foundation-soil system, being able to yield results that are similar to those obtained by the conventional finite element method.

• 산경연구논집
• /
• 제13권9호
• /
• pp.1-9
• /
• 2022

Purpose: This study evaluates the ability to improve the economic welfare of rural communities in Indonesia by using the inequality measures of the distribution of information between leaders and their people as a variable that weakens the capacity of increasing the welfare. Research Design, Data, and Methodology: The research designed by developing an instrument using data validity and reliability testing. Before, primary data collected through interviews, questionnaires, observation, and documentation on the selected respondents. Then, the research method used is mixed methods research, in which quantitative and qualitative methods combined. Result: The finding from this study is that there is an inequality measure in the form of a high gap between the score of information distribution obtained by the village government compared to the score of the community, which has led to the welfare of the village which is still at a moderate level and not ready to become a prosperous society. Conclusion: The weakness of the village community is related to two things, namely the behavior and knowledge of the community about the issues, so the implication is that there must be a strong effort from the central government to ensure that technology is more evenly distributed to all villagers.