• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.9
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• pp.1849-1858
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• 2002

An h-adaptive scheme of first-order least-squares meshfree method is presented. A posteriori error estimates, which can be readily computed from the residual, are also presented. For elliptic problem the error indicators are further improved by applying the Aubin-Nitsche method. In the proposed refinement scheme, Voronoi cells are utilized to insert nodes at appropriate positions. Through numerical examples, it is demonstrated that the error indicators reveal good correlations with the actual errors and the adaptive first-order least-squares meshfree method is effectively applied to the localized problems such as the shock formation in fluid dynamics.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.3
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• pp.98-103
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• 2012

One of the problems in the grinding process using the machining center(MC) with a small diametric wheels is machining error due to decrease of the quill diameter. In this thesis, side-cut grinding is performed with a vitrified bonded CBN wheel on the machining center to establish the basis of the grinding using MC. The grinding force and machining error are investigated experimentally for the change of the machining condition. It is possible to estimate the machining performance by the ratio of the setting depth of cut and actual depth of cut. In addition, the relation between normal grinding force and machining error is presented by the experimental formula.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.1
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• pp.106-112
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• 2008

In this paper, It does the profile measurement of the cam of diesel engine SOHC of the actual object. It uses the measurement of run-out method. This method is that the surface of the object is measured by the sensor when the object rotate, and calculated and displayed by the computer the signal which acquired by sensor. When we acquire the signals, we have two error because of motion and contacting between cam and probe. In this paper, we compensate the motion error while simply liner equation. And we have a solution that we change the figure of probe when we have a contacting error. We compared the data measuring on developed automatic cam profile measuring system with the data measured on CMM.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.613-617
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• 2000

This paper descries the effect of the stylus tip size on the measuring error in surface topography measurement. To analyze the distortional effect of an actual surface geometry originating from the finite stylus size, the surface is modeled as a sinusoid and the stylus tip as a circle. the measuring error is defined as the ratio of the standard deviation of a tracing profile and an original profile. It is shown that this measuring error depends on the amplitude and wavelength of an original profile. In this paper, the spectrum analysis is applied to investigate the distortional effect due to the mechanical filtering of the stylus in the frequency domain. and, the cumulative power spectrum is applied to determinate the minimum wavelength limits to be measured with the various stylus tip radius from these results, a new method to select proper stylus tip radius is proposed.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.2
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• pp.121-127
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• 2008

Micro end-milling has been becoming an important machining process to manufacture a number of small products such as micro-devices, bio-chips, micro-patterns and so on. Despite the importance of micro end-milling, many related researches have given grand efforts to micro end-milling phenomenon, for example, micro end-milling mechanism, cutting force modeling and machinability. This paper strongly concerned actual problem, micro tool deflection, which causes excessive machining errors on the workpiece. To solve this problem, machining error prediction method was proposed through a series of test micro cutting and analysis of their SEM images. An iterative algorithm was applied in order to obtain corrected tool path which allows reducing machining errors in spite of tool deflection. Experiments are carried out to validate the proposed approaches. In result, remarkable error reduction could be obtained.

• Journal of Korea Multimedia Society
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• v.24 no.10
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• pp.1391-1402
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• 2021

This paper focuses use context-sensitive spelling error correction using generative adversarial network. Generative adversarial network[1] are attracting attention as they solve data generation problems that have been a challenge in the field of deep learning. In this paper, sentences are generated using word embedding information and reflected in word distribution representation. We experiment with DCGAN[2] used for the stability of learning in the existing image processing and D2GAN[3] with double discriminator. In this paper, we experimented with how the composition of generative adversarial networks and the change of learning corpus influence the context-sensitive spelling error correction In the experiment, we correction the generated word embedding information and compare the performance with the actual word embedding information.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.2
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• pp.304-310
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• 2020

The technology in 3D modelling have advanced not only maps, heritages, constructions but also trees modelling. By laser scanning(Faro s350) and photogrammetry software(Pix4d) for 3D modelling, this study compared with real coniferous tree and both technology's results about characteristics of shape, texture, and dimensions. As a result, both technologies all showed high reproducibility. The scanning technique showed very good results in the reproduction about bark and leaves. Comparing the detailed dimensions on it, the error between the actual tree and modelling with scanning was 1.7~2.2%, and the scanning result was larger than the actual tree. The error between the actual tree and photogrammetry was only 0.2~0.5%, which was larger than the actual tree. On the other hand, the dark areas's modelling was not fully processed. This study is meaningful as a basic research that can be used for tree DB on BIM for the landscape architecture, landscape design and analysis with AR technology, historical tree and heritage also.

• Journal of Oriental Neuropsychiatry
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• v.32 no.4
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• pp.321-328
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• 2021

Objectives: To compare bone proportional cun and finger-breadth cun in the head area to clearly distinguish the anterior hairline. Methods: In this study, the head area was measured for 50 adult males and females in their 20s with normal hair condition. We compared bone proportional cun and finger-breadth cun in the head area and calculated the error by analyzing the difference between the actual location of the anterior hairline and the location measured with the two methods. Results: There was a significant difference between bone proportional cun and finger-breadth cun in the head area. The two methods showed significant difference from the actual location of the anterior hairline. In addition, as a result of calculating the error between the actual location of the anterior hairline and the location measured by the two methods, the finger-breadth cun had fewer errors than the bone proportional cun. Conclusions: The finger-breadth cun is better than the bone proportional cun as an alternative when it is difficult to find the anterior hairline.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.36 no.1
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• pp.54-59
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• 2000

This paper presents a control system that uses a fuzzy algorithm in controlling the depth of a model midwater trawl net, and experimental results carried out in the circulating water channel by using a model trawl winch system.The fuzzy controller calculates the length of the warp to be changed, based on the depth error between the desired depth and actual depth of the model trawl net and the ratio of change in the depth error. The error and the error change are calculated every sampling time. Then the control input, i.e. desirable length of the warp, is determined by inference from the linguistic control rules which an experienced captain or navigator uses in controlling the depth of the trawl winch controller and the length of the warp is changed. Two kinds of fuzzy control rules were tested, one was obtained from the actual operations used by a skilled skipper or navigator, and the other was a modified from the former by considering the hydrodynamic characteristics of the model trawl system.Two kinds of fuzzy control were tested, one was obtained fro the actual operations used by a skilled skipper or navigator, and the other was a modified from the former by considering the hydrodynamic characteristics of the model trawl system.The results of these model experiments indicate that the proposed fuzzy controllers rapidly follow the desired depth without steady-state error although the desired depth was given in one step, and show robustness properties against changes in the parameters such as the change of the towing sped. Especially, a modified rule shows smaller depth fluctuations and faster setting times than those obtained by a field oriented rule.

• Journal of Ecology and Environment
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• v.41 no.4
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• pp.114-119
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• 2017

This study tried to analyze error range and resolution of drone images using a rotary wing by comparing them with field measurement results and to analyze stands patterns in actual vegetation map preparation by comparing drone images with aerial images provided by National Geographic Information Institute of Korea. A total of 11 ground control points (GCPs) were selected in the area, and coordinates of the points were identified. In the analysis of aerial images taken by a drone, error per pixel was analyzed to be 0.284 cm. Also, digital elevation model (DEM), digital surface model (DSM), and orthomosaic image were abstracted. When drone images were comparatively analyzed with coordinates of ground control points (GCPs), root mean square error (RMSE) was analyzed as 2.36, 1.37, and 5.15 m in the direction of X, Y, and Z. Because of this error, there were some differences in locations between images edited after field measurement and images edited without field measurement. Also, drone images taken in the stream and the forest and 51 and 25 cm resolution aerial images provided by the National Geographic Information Institute of Korea were compared to identify stands patterns. To have a standard to classify polygons according to each aerial image, image analysis software (eCognition) was used. As a result, it was analyzed that drone images made more precise polygons than 51 and 25 cm resolution images provided by the National Geographic Information Institute of Korea. Therefore, if we utilize drones appropriately according to characteristics of subject, we can have advantages in vegetation change survey and general monitoring survey as it can acquire detailed information and can take images continuously.