• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.250-255
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• 2005

For navigation of a service robot, mapping and localization are very important. To estimate the robot pose, the map of the environment is required and it can be built by exploration or SLAM. Exploration is the fundamental task of guiding a robot autonomously during mapping such that it covers the entire environment with its sensors. In this paper, an efficient exploration scheme based on the position probability of the end nodes of a topological map is proposed. In this scheme, a topological map is constructed in real time using the thinning-based approach. The robot then updates the position probability of each end node maintaining its position at the current location based on the Bayesian update rule using the range data. From this probability, the robot can determine whether or not it needs to visit the specific end node to examine the environment around this node. Various experiments show that the proposed exploration scheme can perform exploration more efficiently than other schemes in that, in most cases, exploration for the entire environment can be completed without directly visiting everywhere in the environment.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.8
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• pp.823-831
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• 2008

Since it needs the light computational load and small database, sound source localization method using time delay of arrival(TDOA method) is applied at many research fields such as a robot auditory system, teleconferencing and so on. Researches for time delay estimation, which is the most important thing of TDOA method, had been studied broadly. However studies about factors for time delay estimation are insufficient, especially in case of real environment application. In 1997, Brandstein and Silverman announced that performance of time delay estimation deteriorates as reverberant time of room increases. Even though reverberant time of room is same, performance of estimation is different as the specific part of signals. In order to know that reason, we studied and analyzed the factors for time delay estimation using speech signal and room impulse response. In result, we can know that performance of time delay estimation is changed by different R/D ratio and signal characteristics in spite of same reverberant time. Also, we define the performance index(PI) to show a similar tendency to R/D ratio, and propose the method to improve the performance of time delay estimation with PI.

• Structural Engineering and Mechanics
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• v.54 no.2
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• pp.379-392
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• 2015

A number of acceleration-based damage detection methods have been developed but they have not been widely applied in engineering practices because the acceleration response is insensitive to minor damage of civil structures. In this article, a damage detection approach using the long-gauge strain sensing technology and the principle component analysis technology is proposed. The Long gauge FBG sensor has its special merit for damage detection by measuring the averaged strain over a long-gauge length, and it can be connected each other to make a distributed sensor network for monitoring the large-scale civil infrastructure. A new damage index is defined by performing the principle component analyses of the long-gauge strains measured from the intact and damaged structures respectively. Advantages of the long gauge sensing and the principle component analysis technologies guarantee the effectiveness for structural damage localization. Examples of a simple supported beam and a steel stringer bridge have been investigated to illustrate the successful applications of the proposed method for structural damage detection.

• Journal of the Earthquake Engineering Society of Korea
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• v.7 no.4
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• pp.89-95
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• 2003

In this paper, an algorithm to locate and size damage in a complex truss structure using the time domain response is presented. Sampled response data for specific time interval is spatially expanded over the structure to obtain the mean train energy for each element of the structure. The mean strain energy for each element is, in turn, used to build a damage index that represents the ratio of the stiffness parameter of the pre-damaged to the post-damaged structure. The validity of the methodology is demonstrated using data from a numerical example of a space truss structure with simulated damage. Also in the example, the effects of noisy data on the proposed algorithm are examined by adding random noised to the response data.

• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.4
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• pp.637-644
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• 2019

This paper describes an implementation of a graph-based simultaneous localization and mapping(SLAM) method called the General Graph Optimization. The General Graph Optimization formulates the SLAM problem using nodes and edges. The nodes represent the location and attitude of a robot in time sequence, and the edge between the nodes depict the constraint between the nodes. The constraints are imposed by sensor measurements. The General Graph Optimization solves the problem by optimizing the performance index determined by the constraints. The implementation is verified using the measurement data sets which are open for test of various SLAM methods.

• Structural Monitoring and Maintenance
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• v.9 no.2
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• pp.107-127
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• 2022

Structural health monitoring (SHM) has been related to damage identification with either operational loads or other environmental loading playing a significant complimentary role in terms of structural safety. In this study, a non-parametric method of time frequency analysis on the measurement is used to address the time-frequency representation for modal parameter estimation and system damage identification of structure. The method employs the wavelet decomposition of dynamic data by using the modified complex Morlet wavelet with variable central frequency (MCMW+VCF). Through detail discussion on the selection of model parameter in wavelet analysis, the method is applied to study the dynamic response of both steel structure and reinforced concrete frame under white noise excitation as well as earthquake excitation from shaking table test. Application of the method to building earthquake response measurement is also examined. It is shown that by using the spectrogram generated from MCMW+VCF method, with suitable selected model parameter, one can clearly identify the time-varying modal frequency of the reinforced concrete structure under earthquake excitation. Discussions on the advantages and disadvantages of the method through field experiments are also presented.

• Journal of Nutrition and Health
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• v.24 no.1
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• pp.1-11
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• 1991

In this study. the importance of body fat distribution as an indicator of metabolic aberrations in diabetics was'evaluated. Skinfold thicknesses at eight sites and circumferences at five sites and total body fat content were measured on 105 diabetics. 1) The waist/thigh girth ratio(WTR) was positively correlated(r=0.38-0.54) to plasma glucose levels during oral glucose loading in diabetic men alone. 2) There was no significant difference in serum total cholesterol of diabetics and nondiabetics. However, HDL-cholesterol was significantly lower(p : 0.000. in male and female) in diabetics(male : 36.31$\pm$ 16.98mg/dl, female: 37.89$\pm$14.67mg/dl) than nodiabetics(male 61.75$\pm$14.08mg/dl, female : 62.29$\pm$12.65mg/dl) and serum triglyceride was significantly higher(p=0.0212) in diabetic women(171.90$\pm$ 76.61mg/dl) than nondiabetic women(111.10$\pm$42.84mg/dl) . 3) In both sexes. anthropometric measurements that significantly correlated to serum triglyceride concentration were percentage of ideal body weight. body mass index(BMI) and waist circumference. Positive and significant correlations were found between serum cholestrol, and BMI(R: 0.31, 0.34) and waist circumference(r=0.29) in diabetic men. Moreover, skinfolds of trunk area(r=0.29~0.32) especially abdomen, were closely associated with serum lipids than other fat deposits. Increasing percentage of total body fat content was accompanied by progressively increasing serum triglyceride concentration(r=0.41) in dieabetic men. This study shows that knowledge of body fat localization may help identify risks of carbohydrate intolerance and hyperlipidemia in diabetics.

• Korean Journal of Medicinal Crop Science
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• v.11 no.5
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• pp.402-407
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• 2003

Karyotype analysis and chromosomal localization of 5S and 45S rDNAs using multi-color fluorescence in situ hybridization (McFISH) technique were carried out in Bupleurum longeradiatum. Somatic metaphase chromosome number was 2n=12. Karyotype was composed of three pairs of metacentrics (No.3, 4 and 6) and three pairs of submetacentrics (No. 1, 2 and 5). The length of somatic prometaphase chromosomes ranges from 2.55 to $5.05{\mu}m$ with total length of $18.15\;{\mu}m$. In FISH experiment, one pair of 5S rDNA signals was detected on the pericentromeric region of chromosome 4 and one pair of 45S rDNA signals was detected on the telomeric region of chromosome 2.

• Journal of the Korean Institute of Rural Architecture
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• v.18 no.1
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• pp.47-56
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• 2016

Urban planning is the task to explore measures for bringing order to the change in urban space of future predicted in relation to the size and purpose of the land and a variety of facilities in cities in order to present the environment that can promote the qualitative improvement of activities of residents, ensure orderly urban space of future, and create appropriate urban environment which meets the desire of citizens by anticipating the urban development on the basis of overall activities such as politics, economics, culture, etc, so that the improvement in urban life can be accomplished ultimately. Therefore, this study attempted to examine current conditions information necessary for establishing policies pursuant to the national land development plan and regional development, as well as respond to the needs of urban residents who need the improvement of settlement environment including various amenities for the convenience of life, by shifting away form the macroscopic and one-size-fits top-down approach of development so far and aiming a balanced development of national land in quest for welfare society and by utilizing the urban index as the basic prior task necessary for seeking the shift ind the direction of policies and setting the direction for policies on the basis of the top-down development approach which suits the anticipation and hope of local residents as the subject of development, considering the growing interest in the shift in the policies for regional development in this era of localization. Techniques for urban planning need to be applied, such as the prior planning and the following development, along with the support at the policy level for achieving the improvement in the related sector, in order to induce continuos urban deelopment based on the establishment of healthy and sound settlement environment, and furthermore, the efforts must be drven forward to improve the urban settlement environment while the urban planning and policies are established.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.15 no.1
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• pp.43-58
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• 2002

A methodology to nondestructively locate and estimate size of damage in beam-type structures using a few natural frequencies or a few mode shapes is presented. A damage-localization algorithm to locate damage from changes in natural frequencies and a damage-sizing algorithm to estimate crack-size from natural frequency perturbation are outlined. A damage index algorithm to localize and estimate severity of damage from monitoring changes in mode shapes is outlined. The frequency-based method and the mode-shape-based method are evaluated for several damage scenarios by locating and sizing damage in PS concrete beams lot which a few natural frequencies and mode shapes are generated from finite element models. The result of the analyses indicates that the two methods correctly localize and closely estimate the size of the crack simulated in the test beam.