• Journal of Advanced Navigation Technology
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• v.28 no.2
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• pp.172-177
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• 2024

This paper presents a method to overcome the problem of increasing elevation estimation error when estimating elevation in a multipath situation with radar. A multipath situation means that radar reception signals reflected from the same target come from multiple paths. In non-multipath, the monopulse method is accurate. For the opposite case, the least square error method is accurate. In multipath situation and when the elevation angle is very low, a singular occurs where the least square error estimate diverges. This singular was identified based on the propagation factor, and monopulse and least square error estimation methods were selectively used. As a result, we succeeded in increasing the accuracy of elevation estimation. MATLAB simulations were performed to verify the method proposed in this paper.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.4B
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• pp.365-376
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• 2009

The importance of resonable treatment of tide characteristics has been shown by Kweon, et al. (2005, 2006) for the crest elevation estimation because of a big difference of tidal elevation along Korean coast. For the procedure of crest elevation design, the expected overtopping probability (EOP) was estimated by Kweon, et al. (2006). The comparisons on each sea showed that EOP was lower east, south and west sea in order. The results involved the assumption that the tide and design level wave height meet any time in a year. However, big waves mainly occur in summer or winter in Korean coast, the study focuses on the encounter probability of big waves and seasonal tide level. A theory of the encounter probability is not derived by the present study but it shows reasonable acceptability of the proposed scenario in which the expected overtopping probability could be an index for the crest elevation estimation in Korean coast. The calculation based on the scenario gives the possibility range for the crest elevation estimation which has no tendency of each sea along Korean peninsular. The range is within the expected overtopping probability of 1% in the whole coast of Korea.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.614-617
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• 1995

The unbalance heavy-load elevation driving systems are composed of rotating link-mechanism and hydraulic cylinder which actuates elevation and compensates the static unbalance moment of supporting mechanism. Control and compensation of gun driving is very difficult because these mechanism imply highly nonlinearities due to hydraulic fluid characteristics and mechanical rotation of link-mechanism. In this study, through the analysis of manufactured link-mechanism, the optimal link-mechanism design of the elevating system is suggested. Also to estimate the control performance of the unbalance heavy-load elevation servo-control driving system, modeling and simulation of the system are carried out. To prove the reliability of performance estimation program,simulation results are compared with the experimental results. Both results are similar, therefore this program will be helpful to study the control performance improvement of the system.

• Proceedings of the KIEE Conference
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• 1999.11c
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• pp.703-705
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• 1999

In this paper, we introduce the direction of arrival(DOA) estimation of distributed signal based on the improved ESPRIT algorithm. Most research on the estimation of DOA has been performed based on the assumption that the signal sources are point sources. However, we consider a two-dimensional distributed signal source model using improved ESPRIT algorithm. In the distributed signal source model, a source is represented by two parameters, the azimuth angle and elevation angle. We address the estimation of the elevation and azimuth angles of distributed sources based on the parametric source modeling in the three-dimensional space with two uniform linear arrays. The array output vector is obtained by integrating a steering vector over all direction of arrival with the weighting of a distributed source density function. We also develop an efficient estimation procedures that can reduce the computational complexity. Some examples are shown to demonstrate explicity the estimation procedures under the distributed signal source model.

• Journal of Korea Water Resources Association
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• v.30 no.6
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• pp.721-729
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• 1997

Total scour depth at a bridge is comprised of three components: long-term changes, contraction scour and local scour. Therefore, the analysis of long-term bed elevation changes is very important in the estimation of total scour depth at bridge sites. In this research, long-term bed elevation changes at the Namhan River Bridge are analysed using CHARIMA and HEC-6 models. The results show that, for 5-year steady normal stream flow, the bed elevation is aggreded by 45cm for CHARIMA model but degraded by 5cm for HEC-6 model. For 5-year unsteady flow, the bed elevation is changed greatly and it has a great influence on the estimation of total scour depth. Therefore, to make a proper estimation of total scour depth, not only contraction scour and local scour, but also long-term bed elevation changes should be estimated precisely.

• Journal of Advanced Navigation Technology
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• v.16 no.6
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• pp.952-959
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• 2012

In this paper, we propose an ESPRIT based algorithm for target position estimation with uniform linear array (ULA) and uniform circular array (UCA) at transmitter and receiver, respectively. When UCA is adopted at the receiver, unlike the case of ULA at the receiver, the rotational invariance of the received signal is satisfied. Although there has been an attempt to resolve this issue, the problem of direction of departure estimation has not been considered. In this paper, we provide an ESPRIT based algorithm to simultaneously estimate transmitter elevation angle, receiver elevation angle, and receiver azimuth angle, taking into account the transmitter antennas as well as the receiver antennas.

• Spatial Information Research
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• v.10 no.2
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• pp.263-273
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• 2002

This paper presents desirable water environmental management to a closed watershed. In order to obtain spatially distributed environmental information, GIS data have been used. Elevation data are used to extract stream channels automatically and to divide networks of a watershed. A Digital Elevation Model (DEM) has been developed, validated, and adopted to estimate the runoff of total nitrogen pollutant from watershed. This GIS-linked model can be applied effectively to the watersheds with many sub-streams, and for the estimation of pollutant runoff considering land use change.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.6
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• pp.7-13
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• 1999

The unbalanced heavy-loaded elevation-driving system is composed of link-mechanism, hydraulic cylinder and compensator for the static unbalanced moment of the load. Control and compensation of elevation-driving system is very difficult because these mechanisms imply highly nonlinear properties due to hydraulic fluid characteristics and mechanical rotation of link-mechanism. In this study, through the analysis of the link-mechanism, the optimal design of the link-mechanism is suggested. Also to estimate the control performance of the unbalanced, heavy-loaded servo-controlled system, modeling and simulation of nonlinear system are carried out. To prove the validity of performance estimation program, simulation results are compared with the experimental results. Both results are similar, therefore this program will be helpful to study the improvement of the system control performance.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.3
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• pp.68-75
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• 1999

본 논문은 항공영상으로부터 REM( recovered elevation map)를 추출하여 DEM (digital elevation model)과 정합함으로써 비행체의 위치를 추정하는 기법을 제안하였다. 제안한 알고리듬은 연속항공영상을 이용함으로써 보다 넓은 지역에 대한 REM (recovered elevation map)복원이 가능하여 정합확률이 높아진다. 또한 강건한 거리 척도를 사용함으로써 몇 개의 점에서의 매우 큰 오차에 영향을 받지 않은 알고리듬을 제안하였다. 본 논문에선 몇 개의 항공영상을 가지고 컴퓨터 시뮬레이션을 통하여 제안한 알고리듬의 효용성을 보였다.

• The Journal of Industrial Distribution & Business
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• v.14 no.10
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• pp.35-43
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• 2023

Purpose: The purpose of this study is to analyze the structural relationship between the possibility of socioeconomic class elevation of wage earners, happiness and organizational commitment, and life satisfaction. Research design, data and methodology: Data from the 24th fiscal year (2021) of the Korea Labor Panel data were used for analysis. Only wage earners who measured job satisfaction and organizational engagement were analyzed, and a sample of 9,138 respondents was finally used, excluding missing values. Structural Equation Modeling was performed using AMOS 23.0, and Maximum Likelihood Estimation (MLE) was used as a model estimation method. Results: First, the hypothetical structural model set up for the study was found to be suitable. Second, the Possibility of Socioeconomic Class Elevation of wage earners, happiness, and organizational commitment were found to have a direct impact on life satisfaction. Third, the possibility of improving the socio-economic status of wage earners affects life satisfaction, and happiness and organizational commitment appear to have a partially mediating effect. Conclusions: This study is significant in that it has increased interest in organizational participation and life satisfaction, which were not covered in previous studies on the possibility of wage workers moving up the socioeconomic class.