• Proceedings of the Korea Information Processing Society Conference
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• 2019.05a
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• pp.498-500
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• 2019

Point cloud is a flexible set of points that can provide a scalable geometric representation which can be applied in different computer graphic task. We propose a method based on EdgeConv and densely connected layers to aggregate the features for better classification. Our proposed approach shows significant performance improvement compared to the state-of-the-art deep neural network-based approaches.

• Journal of the Korean Society for Nondestructive Testing
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• v.22 no.4
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• pp.422-429
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• 2002

The identification of ultrasonic flaw signals is a truly difficult task in the angle beam testing of welded joints due to non-relevant signals from the geometric reflectors such as weld roots and counter bores. This paper describes a new approach called "technique for identification of flaw signal using deconvolution(TIFD)" in order to identify the flaw signals in such a problematic situation. The concept of similarity function based on the deconvolution is introduced in the proposed approach. The "reference" signals from both flaws and geometric reflectors and test signals are acquired and normalized. The similarity functions are obtained by deconvolution of test signals with reference signals. The flaw signals could be identified by the patterns of similarity function. The initiative results show great potential of TIFD to distinguish notch comer signals from the geometric reflections.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.10
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• pp.1910-1924
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• 1994

Curved 3D objects represented by range data contain large amounts of information compared with planar objects, but do not have distinct features for matching to those of object models. This makes it difficult to represent and identify a general 3D curved object. This paper introduces a new view-point independent approach to recognizing general 3D curved objects using range data. Our approach makes use of the relative geometric differences between particular points on the object surface and some model points. The model points are prespecified arbitrarily and keeping the task in mind so that the following task can be easily described using the model points. Our approach has several advantages. Since model points are specified arbitrarily and task dependently, further processing can be reduced in application by locating the model points at places which are useful for further operations in the task. The knowledge base is simple with less storage requirement. And, it is easy to compensate the uncertainties of positions estimation caused by noise and quantization error.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.18 no.1
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• pp.32-40
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• 2008

Methyl bromide has been used as a representative fumigant for quarantine, and several poisoning cases have occurred recently by this chemical in Korea. The purpose of this study is to evaluate workers' exposures to airborne methyl bromide in the importing and exporting plant products quarantine companies. Air samples were collected 400/200 mg Anasorb 747TM and were analyzed by gas chromatograph /flame ionization detector according to the Occupational Safety and Health Agency (OSHA) Method PV2040. Geometric mean (GM) and arithmetic mean (AM) of total 27 workers' exposure concentrations to airborne methyl bromide were 1.12 ppm and 0.24 ppm, respectively. Two exposures(12.1 ppm and 12 ppm as 8hr-TWA) of total 27 workers' exposures exceeded the Korean standard (5 ppm) of Ministry Labor, while 4 exposures (15%) exceeded the Threshold Limit Value (TLV) (1 ppm) of American Conference of Governmental Industrial Hygienists (ACGIH). Seven samples (11%) of total 63 short-term air samples exceeded the OSHA Permissible Exposure Limit (PEL) 20 ppm (Ceiling). The opening (management) task in wood fumigation by tent showed the highest short-term exposure concentrations (AM: 18.6 ppm, GM: 0.58 ppm, maximum: 340.7 ppm). The maximum level in treatment task of the same process was 2.01 ppm. Methyl bromide concentrations in opening operation was significantly higher than that in treatment operation (p<0.05). In conclusion, the GM of workers' 8hr-TWA exposures to airborne methyl chloride in the importing/exporting plant quarantine industry was estimated below the ACGIH TLV (1 ppm). However, opening task in the fumigation of wood being covered with tent or fumigation of pant products in container showed the levels exceeding ACGIH TLV (1 ppm), and opening task in the fumigation of wood being covered with tent showed the level exceeding the Korean standard of Ministry of Labor (5 ppm).

• Journal of the Korean Society of Industry Convergence
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• v.20 no.4
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• pp.299-305
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• 2017

This study proposes a new technique to design and control of robot hand gripper for assembling and disassembling of a machine parts. The motion equation describing dynamics of the manipulators and object together with geometric constraint is formulated by Lagrange-Euler's equation. And the problems of controlling both the grasping force and the rotation angle of the grasped object under the constraints are analyzed. The effect of geometric constraints and a method of computer simulation for overall system is verified. Finally, it is illustrated that even in case of there exists a sensory feedback from sensing data of the rotational angle of the object to command inputs control of joint and this feedback connection from sensing data to control grasping of machinery parts.

• Computers and Concrete
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• v.17 no.2
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• pp.241-253
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• 2016

Depending on the researcher, the effect of prestressing on the natural frequency of a PSC (prestressed concrete) structure appear to have been interpreted differently. Most laboratory tests on PSC beams available showed that the natural frequency is increased appreciably by prestressing. On the other hand, some other references based on field experience argued that the dynamic response of a PSC structure does not change regardless of the prestressing applied. Therefore, the deduced conclusions are inconsistent. Because an experiment with and without prestressing is a difficult task on a full size PSC bridge, the change in natural frequency of a PSC bridge due to prestressing may not be examined through field measurements. The study examined analytically the effects of prestressing on the natural frequency of PSC bridges. A finite element program for an undamped dynamic motion of a beam-tendon system was developed with additional geometric stiffness. The analytical results confirm that a key parameter in changing the natural frequency due to prestressing is the relative ratio of prestressing to the total weight of the structure rather than the prestressing itself.

• Proceedings of the KSRS Conference
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• v.2
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• pp.643-646
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• 2006

This paper addresses the approach to extract linear features from satellite imagery using an efficient segmentation method. The extraction of linear features from satellite images has been the main concern of many scientists. There is a need to develop a more capable and cost effective method for the Iranian map revision tasks. The conventional approaches for producing, maintaining, and updating GIS map are time consuming and costly process. Hence, this research is intended to investigate how to obtain linear features from SPOT satellite imagery. This was accomplished using a discontinuity-based segmentation technique that encompasses four stages: low level bottom-up, middle level bottom-up, edge thinning and accuracy assessment. The first step is geometric correction and noise removal using suitable operator. The second step includes choosing the appropriate edge detection method, finding its proper threshold and designing the built-up image. The next step is implementing edge thinning method using mathematical morphology technique. Lastly, the geometric accuracy assessment task for feature extraction as well as an assessment for the built-up result has been carried out. Overall, this approach has been applied successfully for linear feature extraction from SPOT image.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.16 no.4
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• pp.1166-1186
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• 2022

Artistic font design has become an integral part of visual media. However, without prior knowledge of the font domain, it is difficult to create distinct font styles. When the number of characters is limited, this task becomes easier (e.g., only Latin characters). However, designing CJK (Chinese, Japanese, and Korean) characters presents a challenge due to the large number of character sets and complexity of the glyph components in these languages. Numerous studies have been conducted on automating the font design process using generative adversarial networks (GANs). Existing methods rely heavily on reference fonts and perform font style conversions between different fonts. Additionally, rather than capturing style information for a target font via multiple style images, most methods do so via a single font image. In this paper, we propose a network architecture for generating multilingual font sets that makes use of geometric structures as content. Additionally, to acquire sufficient style information, we employ multiple style images belonging to a single font style simultaneously to extract global font style-specific information. By utilizing the geometric structural information of content and a few stylized images, our model can generate an entire font set while maintaining the style. Extensive experiments were conducted to demonstrate the proposed model's superiority over several baseline methods. Additionally, we conducted ablation studies to validate our proposed network architecture.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.16 no.6
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• pp.2044-2059
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• 2022

Recent works have shown that the geometric constraint can be harnessed to boost the performance of CNN-based camera localization. However, the existing strategies are limited to imposing image-level constraint between pose pairs, which is weak and coarse-gained. In this paper, we introduce a pixel-level epipolar geometry constraint to vanilla localization framework without the ground-truth 3D information. Dubbed EpiLoc, our method establishes the geometric relationship between pixels in different images by utilizing the epipolar geometry thus forcing the network to regress more accurate poses. We also propose a variant called EpiSingle to cope with non-sequential training images, which can construct the epipolar geometry constraint based on a single image in a self-supervised manner. Extensive experiments on the public indoor 7Scenes and outdoor RobotCar datasets show that the proposed pixel-level constraint is valuable, and helps our EpiLoc achieve state-of-the-art results in the end-to-end camera localization task.

• Journal of Information Processing Systems
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• v.19 no.6
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• pp.791-802
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• 2023

The manual inspection of photovoltaic (PV) panels to meet the requirements of inspection work for large-scale PV power plants is challenging. We present a hot spot detection and positioning method to detect hot spots in batches and locate their latitudes and longitudes. First, a network based on the YOLOv3 architecture was utilized to identify hot spots. The innovation is to modify the RU_1 unit in the YOLOv3 model for hot spot detection in the far field of view and add a neural network residual unit for fusion. In addition, because of the misidentification problem in the infrared images of the solar PV panels, the DeepLab v3+ model was adopted to segment the PV panels to filter out the misidentification caused by bright spots on the ground. Finally, the latitude and longitude of the hot spot are calculated according to the geometric positioning method utilizing known information such as the drone's yaw angle, shooting height, and lens field-of-view. The experimental results indicate that the hot spot recognition rate accuracy is above 98%. When keeping the drone 25 m off the ground, the hot spot positioning error is at the decimeter level.