• Proceedings of the Korean Society For Composite Materials Conference
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• 2000.04a
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• pp.80-84
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• 2000

A mesh superposition technique is presented for an efficient analysis of structural behavior. Refined child mesh is superimposed over parent elements for the region of interest. It is a kind of adaptive mesh refinement, which allows locally refined mesh without introducing transition region or multipoint constraints. Proper boundary condition is necessary to avoid redundant rigid body motion and kinematic compatibility between neighbor elements. Delamination buckling analysis is conducted to demonstrate accuracy and efficiency of the present method.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.1013-1016
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• 1995

This paper deals with dynamics and control of a PRP6-DOF parallel manipulator. Dynamic modeling includes the effect of inertia of all links in the mechanism to increase modeling accuracy. Kinematic analysis about forward and inverse kinematics is also explained. Using Lagrange-D' Alambert method we get equations of motions in a link space which fully represent 6DOF motions of the manipulator.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.1095-1096
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• 2008

By adding height compensation to the usual 3 points skew adjustment device, an improved functional skew adjustment device is implemented in this paper. The proposed skew adjustment device is for traverse which will be adapted to BD and HD player system requiring more accuracy. and It can adjust not only R/T skew but also height. The system is composed of personal computer, control box, kinematic mechanism device and bar-code reader device. Application programs are implemented by visual basic.

• 한국공간정보시스템학회:학술대회논문집
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• 2004.05a
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• pp.37-42
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• 2004

The primary objective of this paper is to trace the post-buckling behavior of space trusses in the inelastic range. Modeled member material behavior characteristics of struts in the post-critical elasto-plastic stage are determined and three types of idealized hardening rules are described. To perform this analysis, the present work is used the current stiffness parameter method combined with the cylinderical arc-length method. Numerical examples are presented to illustrate the accuracy and the application of the numerical solutions introduced above.

• Steel and Composite Structures
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• v.34 no.1
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• pp.141-154
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• 2020

In the present paper, free vibration analysis of angle-ply laminated composite annular and circular plates is performed by numerical methods. First-order shear deformation plate theory is used for kinematic relations. The related governing equations of motion are discretized via differential quadrature and discrete singular convolution methods. Frequency values are obtained for different lamina scheme, thickness-to-radius ratio, and mode numbers. The advantages and accuracy of these two methods are also tested in detail.

• Journal of Positioning, Navigation, and Timing
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• v.7 no.1
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• pp.43-52
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• 2018

In recent years, the need of high accuracy navigation for vehicles has increased due to the development of autonomous driving vehicles and increase in land transportation convenience. This study is performed for vehicle users to achieve a performance of centimeter-level positioning accuracy by utilizing Compact Network Real-time Kinematic (RTK) that is applicable as a national-level infrastructure. To this end, medium-baseline RTK was implemented in real time to estimate accurate integer ambiguities between reference stations for reliable generation of Network RTK correction using the linear combination of carrier-phase observations and L1/L2 pseudo-range measurements. The residual tropospheric error was estimated in real time to improve the accuracy of double-differenced integer ambiguity resolution between network configuration reference stations that have at least 30 km or longer baseline distance. In addition, C++ based software was developed to enable real-time generation and broadcasting of Compact Network RTK correction information by utilizing an accurately estimated double-differenced integer ambiguity values. As a result, the horizontal and vertical 95% accuracy was 2.5cm and 5.2cm, respectively, without performance degradation due to user's position change within the network.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.454-458
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• 2007

Nonpoint source (NPS) pollution is a serious problem causing the degradation of soil and water quality. Concentrated overland flow is the primary transport mechanism for a large amount of NPS pollutants from hillslope areas to downslope areas in a watershed. In this study, a soil erosion model, nLS model, to identify transitional overland flow regions (i.e., ephemeral gully head areas) was developed using the kinematic wave overland flow theory. Spatial data, including digital elevation models (DEMs), soil, and landcover, were used in the GIS-based model algorithm. The model was calibrated and validated using gully head locations in a large agricultural watershed, which were identified using 1-m aerial photography. The model performance was better than two previous approaches; the overall accuracy of the nLS model was 72 % to 87 % in one calibration subwatershed and the mean overall accuracy was 75 to 89 % in four validation subwatersheds, showing that the model well predicted potential transitional erosion areas at different watersheds. However, the user accuracy in calibration and validation was still low. To improve the user accuracy and study the effects of DEM resolution, finer resolution DEMs may be preferred because DEM grid is strongly sensitive to estimating model parameters. Information gained from this study can improve assessing soil erosion process due to concentrated overland flow as well as analyze the effect of microtopographic landscapes, such as riparian buffer areas, in NPS control.

• Journal of Korean Society for Geospatial Information Science
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• v.17 no.1
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• pp.37-42
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• 2009

The accuracy of RTK GPS is limited by the distance dependent errors from orbit, ionosphere and troposphere, as the distance between the rover and the base station increases in the Real Time Kinematic surveying. To solve this problem, VRS system has installed. This study would estimated the accuracy of cadastral detail surveying, which is used on the VRS RTK instead of Total Station and RTK GPS demand for various equipments and time. As a result of study, the positioning accuracy of the VRS RTK and RTK GPS surveying make no greate difference, as RMSE of VRS RTK surveying is 0.144m and that of RTK GPS surveying is 0.146m and the new method would be more efficient.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2003.10a
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• pp.123-128
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• 2003

Data acquired from digital Imagery were processed via Delphi, an object-oriented programming language to develop a computer aided program, that allows us to build up the information on road horizontal alignment(BC, EC, R, IP). And the developed program could maximize the visual effects better than traditional programs, because it used many image data. Comparing with data from traditional horizontal alignment extraction programs based on the principle of least square method, the data acquired by horizontal alignment information and kinematic GPS out of the developed road information systems showed the enhanced accuracy of IP value up to about 2m in the direction of X, Y axes, where the accuracy of curve radius(R) becomes enhanced up to about 2.5 m.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.12 no.5
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• pp.163-169
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• 2013

The objective of this study is to replace labor intensive forging processes by an automated system. For achieving it, an exclusive mechanism that consists of a positioner, an arm, and a hanger is configured to handle hot forging objects. Also, a structural analysis is applied to the horizontal motion unit, which is the most highly loaded, in order to verify its validity. In addition, its possibility is also verified through identifying the performance of the proposed system before applying it to sites. As a result, the major characteristic items, such as positioning accuracy, material diameter, object traveling weight, product failure rate, and forging process rate, in this system are perfectly verified for applying it to manufacturing sites.