• Proceedings of the KSME Conference
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• 2004.04a
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• pp.834-839
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• 2004

In this paper, modeling methods for the structural dynamic analysis employing single reference frame are presented and their modal and transient analysis results are compared. The geometric stiffening effects often occur when structures undergo large overall motion. These effects were considered in several structural previous modeling methods but the role of reference frame has never been scrutinized. In this study, modeling methods employing single reference frame are presented, and their numerical results are compared. The results show that discrepancy between the two modeling methods increases as the eccentricity of the structural system and the magnitude of the large overall motion increase.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.6
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• pp.890-897
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• 2003

This paper compares engineering estimation schemes of C＊ and creep COD for circumferential and axial through-wall cracked pipes at elevated temperatures with detailed 3-D elastic-creep finite element results. Engineering estimation schemes included the GE/EPRI method, the reference stress method where reference stress is defined based on the plastic limit load and the enhanced reference stress method where the reference stress is defined based on the optimized reference load. Systematic investigations are made not only on the effect of creep-deformation behaviour on C＊ and creep COD, but also on effects of the crack location, the pipe geometry, the crack length and the loading mode. Comparison of the FE results with engineering estimations provides that for idealized power law creep, estimated C＊ and COD rate results from the GE/EPRI method agree best with FE results. For general creep-deformation laws where either primary or tertiary creep is important and thus the GE/EPRI method is hard to apply, on the other hand, the enhanced reference stress method provides more accurate and robust estimations for C* and COD rate than the reference stress method.

• Journal of Sensor Science and Technology
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• v.13 no.2
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• pp.114-120
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• 2004

The $Comet{\acute{e}}$ Consultatif de $Thermom{\acute{e}}trie$ (CCT) under the Comete International des Poids et Measures (CIPM) has decided to perform the Key Comparison (KC) for triple point of water cells used as a reference fixed point of thermometry at the 21st meeting held at November 2001, and the Bureau International des Poids et Measures (BIPM) has been nominated as a KC coordinator. According to the KC protocol prepared by BIPM, KRISS performed the KC experiments and evaluate a uncertainty. The temperature difference between two reference cells for the Korea Research Institute of Standards and Science (KRISS) and a test cell for the transfer standard, which is moved to BIPM was 0.024 mK and the combined standard uncertainty evaluated 0.055 mK.

• Journal of Korean Library and Information Science Society
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• v.44 no.1
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• pp.409-432
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• 2013

The purpose of this study is to examine 5 writing guidelines of reference collection development policy(RCDP) and to identify major elements of RCDP through the comparison and analysis of 24 RCDP in academic libraries in the U.S. As a result of this study, a total of 9 elements(5 core elements and 4 selective elements) were identified. Five core elements were (1) introduction, (2) scope, size, and level, (3) format, (4) types, and (5) management(i.e., selection, weeding, evaluation, and responsibilities) of reference collection. The results of this study would be helpful to those academic libraries which are planning to write RCDP in academic libraries in the near future.

• International Journal of Aeronautical and Space Sciences
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• v.17 no.2
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• pp.222-231
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• 2016

This paper proposes a new method achieving computationally efficient attitude reference system for low cost strapdown sensors and microprocessor platform. The main idea in this method is to define and compare velocity differential vectors, geometrically computed from INS and GPS data with different update rate, for generating attitude error measurements which is further used for filter construction. A quaternion based Kalman filter configuration is applied for the attitude estimation with the adapted measurement model of differential vector comparison. Linearized model for Extended Kalman Filter and low pass filtered characteristics of measurement greatly extend the affordability of the proposed algorithm to the field of simple low cost embedded systems. For performance verification, experiment are done employing a practical low cost MEMS IMU and GPS receiver specification. Performance comparison with a high grade navigation system demonstrated good estimation result.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.12 no.1
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• pp.95-106
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• 1994

The purpose of this paper is to establish the optimum reference field as testing some geopotential model, gravity data and GPS data. We have to decide a best fitting geopotential model as a reference surface for establishing the optimum geoid solutions. We conduct some tests on the Korean Peninsula gravity data to establish which of the model would be prove to be the best one. Three ways were used to compare the geopotential coefficient solutions. One of the tests is to compare the residual gravity anomaly remaining after the anomaly computed from the geopotential model has been subtracted from the "observed" gravity anomaly. The second method is a comparison of several geopotential solutions in terms of differences in gravity anomalies and quasi-geoid undulations. The third method is a comparison between the undulation obtained by GPS and the corresponding undulation from each geopotential model. The result showed that OSU91A model is a best fitting model as a reference in the region of Korean Peninsula.Peninsula.

• Korean Journal of Remote Sensing
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• v.32 no.1
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• pp.13-24
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• 2016

This paper presents a method to evaluate the performance of subpixel localization operators using target image data. Subpixel localization of edges is important to extract the precise shape of objects from images. In this study, each target image was designed to provide reference lines and edges to which the localization operators can be applied. We selected two types of moment-based operators: Gray-level Moment (GM) operator and Spatial Moment (SM) operator for comparison. The original edge localization operators with kernel size 5 are tested and their extended versions with kernel size 7 are also tested. Target images were collected with varying Camera-to-Object Distance (COD). From the target images, reference lines are estimated and edge profiles along the estimated reference lines are accumulated. Then, evaluation of the performance of edge localization operators was performed by comparing the locations calculated by each operator and by superimposing them on edge profiles. Also, enhancement of edge localization by increasing the kernel size was also quantified. The experimental result shows that the SM operator whose kernel size is 7 provides higher accuracy than other operators implemented in this study.

• Proceedings of the KIEE Conference
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• 2006.07d
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• pp.2077-2078
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• 2006

This paper describes the development or a closed-loop Strapdown Attitude Reference System (SARS) algorithm integrated filtering estimator for determining attitude reference for railway and aviation system using fuzzy inference. The SARS consists of 3 single-axis rate gyms in conjunction with 2 single-axis accelerometers. For optimal values of fuzzy systems, we utilize on-line scheduling method for initial values and then use genetic algorithms for fine tuning. Implementation using experimental test data of unmanned aerial vehicle has been performed in order to verify the estimation. The proposed fuzzy inference based SARS demonstrate that more accurate performance can be achieved in comparison with conventional one. The estimation results were compared with the on-board vertical gyro as the reference standard.

• Proceedings of the KSME Conference
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• 2001.11a
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• pp.80-86
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• 2001

An engineering estimation equation for the crack opening displacement (COD) is proposed for a complex cracked pipe, based on the reference stress approach. To define the reference stress, a simple plastic limit load analysis for the complex cracked pipe subjected to combined bending and tension is performed considering the crack closure effect in the compressive-stressed region. Comparison with ten published test data and the results from existing method shows that the present method not only reduces non-conservatism associated with the existing method, but also provides consistent and overall satisfactory results.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.2
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• pp.57-59
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• 2006

In order to apply the network adjustment, the correct ambiguities between each of reference stations must be calculated. This paper focused on the comparison of ambiguity resolution between the reference stations. Three hours test data with different baseline length from 20 km to 60 km have been analyzed. The results show that the time-to-fix between 20 km and 40 km is typically under 1 minute. However, over 60km baseline, the time-to-fix performance degrades.