• Korean Journal of Construction Engineering and Management
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• v.23 no.5
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• pp.87-97
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• 2022

Although the use of BIM in architectural projects has increased, repetitive modeling tasks and frequent design errors remain as obstacles to the practical application of BIM. In particular, interior finishing elements include the most varied and detailed requirements, and thus requires improving its modelling efficiency and resolving potential design errors. Recently, visual programming-based modules has gained traction as a way to automate a series of repetitive modeling tasks. However, existing approaches do not adequately reflect the practical modeling needs and focus only on replacing siimple, repetitive tasks. This study developed and evaluated the performance of three modules for automatic detailing of walls, floors and ceilings. The three elements were selected by analyzing the man-hours and the number of errors that typically occur when detailing BIM models. The modules were then applied to automatically detail a sample commercial facility BIM model. Results showed that the implementations met the practical modeling requirements identified by actual modelers of an construction management firm.

• Journal of Positioning, Navigation, and Timing
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• v.4 no.1
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• pp.1-7
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• 2015

In the case of an unmanned aerial vehicle (UAV) equipped with a GNSS sensor, a boundary line where the vehicle can actually exist can be calculated using a navigation error model, and safe navigation (e.g., precise landing and collision prevention) can be supported based on this boundary line. Therefore, for the safe operation of UAV, a model for the position error of UAV needs to be established in advance. In this study, the multipath error of a GNSS sensor installed at UAV was modeled through a flight test, and this was analyzed and compared with the error model of an existing manned aircraft. The flight test was conducted based on a scenario in which UAV performs hovering at an altitude of 40 m, and it was found that the multipath error value was well bound by the error model of an existing manned aircraft. This result indicates that the error model of an existing manned aircraft can be used in operation environments similar to the scenario for the flight test. Also, in this study, a scenario for the operation of multiple UAVs was considered, and the correlation between the multipath errors of the UAVs was analyzed. The result of the analysis showed that the correlation between the multipath errors of the UAVs was not large, indicating that the multipath errors of the UAVs cannot be canceled out.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.3
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• pp.387-393
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• 2012

It is very difficult to determine suitable cutting conditions in order to obtain accurate cutting profiles because machining errors caused by tool deflection depend upon cutting conditions. In this study the relationship between real cutting profiles (inclined shapes and machining errors) and cutting conditions was modeled in order to fabricate draft angle on micro molds. CCD (Central Composite Design) of DOE (Design Of Experiment) and RSM (Response Surface Method) were applied in order to model the relationship between cutting conditions and machining errors. In order to use CCD the range of radial depth of cut was chosen by $10-90{\mu}m$ and the range of feedrate was chosen by 200-300mm/min, and 9 points of cutting conditions were chosen inside determined ranges. Then, actual cutting processes were carried out as respect to 9 points of cutting conditions, draft angles and real cutting profiles were measured on cutting profiles, each response surface function was determined by conducting response surface analysis and the functions were represented by 3-dimensional graphs, contour lines and $101{\times}101$ matrices. Consequently it is possible to determine suitable cutting conditions in order to obtain arbitrary given draft angles and cutting profiles by using modeling. To validate proposed approach in this study suitable cutting conditions were determined by modeling in order to obtain arbitrary given draft angle and cutting profile, and actual cutting processes were carried out. About 95% of good agreement between predicted and measured values was obtained.

• Journal of KIBIM
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• v.14 no.3
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• pp.13-21
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• 2024

This study aims to simplify the rebar quantity estimation process during the detailed design stage of buildings by addressing identified issues in the existing rebar quantity estimation process and establishing a BIM-based simplification method. To validate the applicability of the proposed method, it was applied to a case study of 'K' High School, with the results compared to rebar quantities from shop drawings to assess usability in real projects. It showed an error rate of 1.4% for SHD22S and 2.63% for HD10 among the types of rebar used in the case model. SHD22S, used as the main rebar in the columns, exhibited this error due to differences in the calculation method for splice and anchorage lengths. HD10, used as stirrup rebar in the columns, showed errors due to the omission of hook length considerations in the simplified estimation formula. Although these discrepancies resulted in cumulative errors of 10 to 20 meters, the error rates of 1.4% and 2.63% respectively fall within the generally accepted rebar overage rate of 5%, suggesting that this method is sufficiently accurate for quantity estimation during the detailed design stage. This study presents a method for efficiently estimating rebar quantities based on BIM during the detailed design stage. While traditional 2D quantity estimation and BIM-based methods often suffer from inefficiencies due to repetitive tasks and high modeling complexity, the proposed method assumes BIM models at LOD200, which are less complex and automate most of the structural information required for rebar quantity estimation, thereby reducing repetitive tasks. However, to further minimize errors, especially those related to hook and anchorage length calculations, additional research is needed to refine the estimation process and expand its applicability to the entire building's rebar quantity estimation.

• MALSORI
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• no.43
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• pp.137-150
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• 2002

Speech segmentation at phoneme level is important for corpus-based text-to-speech synthesis. In this paper, we examine acoustic modeling methods to improve the performance of automatic speech segmentation system based on Hidden Markov Model (HMM). We compare monophone and triphone models, and evaluate several model training approaches. In addition, we employ an energy-based postprocessing scheme to make correction of frequent boundary location errors between silence and speech sounds. Experimental results show that our system provides 71.3% and 84.2% correct boundary locations given tolerance of 10 ms and 20 ms, respectively.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.725-730
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• 2002

This paper presents an efficient modeling method for open cracked beam structures. An equivalent bending spring model is introduced to represent the structural weakening effect in the presence of open cracks. The proposed method adopts the exact dynamic element method (EDEM) to avoid the difficulty and numerical errors in association with re-meshing the structure. The proposed method is rigorously compared with a commercial finite element code. Experiments are also performed to validate the proposed modeling method. Finally, a diagnostic scheme for open cracked beam structures is proposed and demonstrated through a numerical example.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.23 no.57
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• pp.87-92
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• 2000

This paper describes a three dimensional parametric modeling system for transmission gears of tractor. In conventional design and manufacturing, information about three dimensional shapes has been described in engineering drawings. However drawing based design presents several problems; 1) communication errors between the designer and the modeller or manufacturer. 2) time taken and costs incurred in the design process. To solve these problems the system of parametric design based modeling has been proposed. Developed system in this paper consists of four steps; 1) parametric design of transmission gears with a solid modeler. 2) evaluation of gear geometry and strength. 3) dynamic simulation for gear interference check. 4) gear stress analysis with a CAE software. The proposed system has been tested in the fields and found to be a useful system.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.43-46
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• 2000

Optical triangulation displacement sensors(0TDSs) are widely used for their simple struchlre, high resolution, and long operating range. However, there are several factors that must be taken into account in order to obtain high accuracy and reliability Measurement errors from inclinations a？ an object surface, prohe signal fluctuations generated by speckle effects. power vanation of a light source, electronic noises, and so on. Previous models of OTDSs can not show reasonable behavior as change of surface inclination and shape of light intensity distribution on the detector. In this paper, we propose a new and reasonable modeling for diffise-type OTDSs based on a geometrical optics. To verify propriety of new modeling, we take basic experiments. Shape of light intensity distribution is asymmetric in both simulation result and experimental result. Both simulation result and experimental result show same tendency of light intensity distribution movement as changing surface inclination

• Speech Sciences
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• v.10 no.3
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• pp.225-239
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• 2003

In this paper, we develop a keyword spotting system using vocabulary-independent speech recognition technique, and investigate several non-keyword modeling and post-processing methods to improve its performance. In order to model non-keyword speech segments, monophone clustering and Gaussian Mixture Model (GMM) are considered. We employ likelihood ratio scoring method for the post-processing schemes to verify the recognition results, and filler models, anti-subword models and N-best decoding results are considered as an alternative hypothesis for likelihood ratio scoring. We also examine different methods to construct anti-subword models. We evaluate the performance of our system on the automatic telephone exchange service task. The results show that GMM-based non-keyword modeling yields better performance than that using monophone clustering. According to the post-processing experiment, the method using anti-keyword model based on Kullback-Leibler distance and N-best decoding method show better performance than other methods, and we could reduce more than 50% of keyword recognition errors with keyword rejection rate of 5%.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.763-767
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• 2002

This paper explores a structuring method for solid modeling processes of an automobile automatic transmission-lever design. The aim of this work is to establish standard procedures to minimize iterations and trial and errors during the product development process to increase development time and costs. The design of the transmission-lever is periodically required to be changed with the model change of an automobile. The transmission-lever design process has mainly depended on the designer's experience. It causes to make difficulties to handle the dependency of components. The design process can be improved by resolving the dependency problem using the DSM. The process of applying the DSM provides a systematic way for the solid modeling of transmission-lever by the consideration of geometry dependency.