• Journal of the Korea Society of Computer and Information
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• v.11 no.3
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• pp.87-96
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• 2006

Most conventional database systems support specific queries that are concerned only with data that match a query qualification precisely. A cooperative query answering supports query analysis, query relaxation and provides approximate answers as well as exact answers. The key problem in the cooperative answering is how to provide an approximate functionality for alphanumeric as well as categorical queries. In this paper, we propose a metricized knowledge abstraction hierarchy that supports multi-level data abstraction hierarchy and distance metric among data values. In order to facilitate the query relaxation, a knowledge representation framework has been adopted, which accommodates semantic relationships or distance metrics to represent similarities among data values. The numeric domains also compatibly incorporated in the knowledge abstraction hierarchy by calculating the distance between target record and neighbor records.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.11
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• pp.31-37
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• 2018

This paper proposes an effective single-image haze-removal algorithm with low complexity by using a dual dark channel prior (DCP) and an adaptive brightness correction technique. The dark channel of a small patch preserves the edge information of the image, but is sensitive to noise and local brightness variations. On the other hand, the dark channel of a large patch is advantageous in estimation of the exact haze value, but halo effects from block effects deteriorate haze-removal performance. In order to solve this problem, the proposed algorithm builds a dual DCP as a combination of dark channels from patches with different sizes, and this meets low-memory and low-complexity requirements, while the conventional method uses a matting technique, which requires a large amount of memory and heavy computations. Moreover, an adaptive brightness correction technique that is applied to the recovered image preserves the objects in the image more clearly. Experimental results for various hazy images demonstrate that the proposed algorithm removes haze effectively, while requiring much fewer computations and less memory than conventional methods.

• Journal of IKEEE
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• v.23 no.2
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• pp.358-363
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• 2019

In this paper, we implemented a welfare system for the elderly living alone, disabled, or babies to provide fast incident response in case of emergency situations. The proposed system can quickly recognize emergency situations using heart rate sensors and real-time image sharing. The sensors attached on a wrist band monitor the heart rate along with relevant bio signals of clients and send alarms to guardians in the emergency situations. At the same time, the real-time image signals are captured using OpenCV and sent to the guardians in order to give the exact information for fast and appropriate response to handle the situation. In the proposed system, the camera works only in the emergency situations so as to provide enough privacy to the client's every day life.

• Smart Structures and Systems
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• v.24 no.3
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• pp.333-343
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• 2019

The possibility of adopting vibration-powered wireless nodes has been largely investigated in the last years. Among the available technologies based on the piezoelectric effect, the most common ones consist of a vibrating beam covered by electroactive layers. Another energy harvesting strategy is based on the use of piezoelectric strips attached to a hosting structure subjected to dynamic loads. The hosting structure, for example, can be the system to be equipped with wireless nodes. Such strategy has received few attentions so far and no analytical studies have been presented yet. Hence, the original contribution of the present paper is concerned with the development of analytical solutions for the electrodynamic analysis and design of piezoelectric polymeric strips attached to relatively large linear elastic structural systems subjected to random vibrations at the base. Specifically, it is assumed that the dynamics of the hosting structure is dominated by the fundamental vibration mode only, and thus it is reduced to a linear elastic single-degree-of-freedom system. On the other hand, the random excitation at the base of the hosting structure is simulated by filtering a white Gaussian noise through a linear second-order filter. The electromechanical force exerted by the polymeric strip is negligible compared with other forces generated by the large hosting structure to which it is attached. By assuming a simplified electrical interface, useful new exact analytical expressions are derived to assess the generated electric power and the integrity of the harvester as well as to facilitate its optimum design.

• Imaging Science in Dentistry
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• v.50 no.4
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• pp.281-290
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• 2020

Purpose: The objective of the present study was to evaluate the prevalence of dental implants positioning errors and their associations with adjacent structures and anatomical variations by means of cone-beam computed tomography (CBCT). Materials and Methods: CBCT images of 207 patients (584 dental implants) were evaluated by 2 oral radiologists. The distance between the implant and the adjacent teeth/implants was measured and classified as adequate (≥1.5 mm and ≥3 mm, respectively) or inadequate. The presence of thread exposure, cortical perforation, implant dehiscence, implant penetration into adjacent structures, and anatomical variations was also recorded. The incisor canal diameter and the depth of the concavity of the submandibular fossa were measured in order to evaluate their correlations with the frequency of implant penetration in these structures. Descriptive analyses, the Fisher exact test, and Spearman correlation analysis were performed (α=0.05). Results: The overall prevalence of positioning errors was 82.9%. The most common error was the inadequate distance between the implant and the adjacent teeth/implants. The presence of anatomical variations did not significantly influence the overall prevalence of errors (P>0.05). There was a positive correlation between the diameter of the incisor canal and the frequency of implant penetration in this structure (r=0.232, P<0.05). Conclusion: There was a high prevalence of dental implant positioning errors, and positioning errors were not associated with the presence of anatomical variations. Professionals should be aware of the space available for implant placement during the preoperative planning stage.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.18 no.5
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• pp.41-47
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• 2008

In a network environment, when a user requests a server's service, he/she must pass an examination of user authentication. Through this process, the server can determine if the user can use the provided services and the exact access rights of this user in these services. In these authentication schemes, the security of private information became an important issue. For this reason, many suggestions have been made in order to protect the privacy of users and smart cards have been widely used for authentication systems providing anonymity of users recently. An remote user authentication system using smart cards is a very practical solution to validate the eligibility of a user and provide secure communication. However, there are no studies in attribute-based authentication schemes using smart cards so far. In this paper, we propose a novel user authentication scheme using smart cards based on attributes. The major merits include : (1) the proposed scheme achieves the low-computation requirement for smart cards; (2) user only needs to register once and can use permitted various services according to attributes; (3) the proposed scheme guarantees perfect anonymity to remote server.

• The Journal of the Korea Contents Association
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• v.22 no.3
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• pp.105-111
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• 2022

Multiple-choice survey types have been mainly performed to analyze students' needs for online classes. However, in order to analyze the exact needs of students, unstructured data analysis by answer for essay question is required. Big data is applied in various fields because it is possible to analyze unstructured data. This study aims to investigate and analyze what students want subjects or topics for software lecture in general education that process on non-face-to-face online teaching methods. As for the experimental method, keyword analysis and association analysis of big data were performed with unstructured data by giving a subjective questionnaire to students. By the result, we are able to know the keyword what the students want for software lecture, so it will be an important data for planning and designing software lecture of liberal arts in the future as students can grasp the topics they want to learn.

• Advances in concrete construction
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• v.14 no.5
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• pp.299-307
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• 2022

Cement-based matrixes have low tensile strength and negligible ductility. Adding fibres to these matrixes will improve their mechanical properties and make these composites suitable for structural applications. Post-cracking tensile strength of steel fibers-reinforced cementitious composite materials is directly related to the number of transverse fibers passing through the crack width and the pulling-out behavior of each of the fibers. Therefore, the exact recognition of the pullout behavior of single fibers is necessary to understand the uniaxial tensile and bending behavior of steel fiber-reinforced concrete. In this paper, an experimental study has been carried out on the pullout behavior of 3D (steel fibers with totally two hooks at both ends), 4D (steel fibers with a total of four hooks at both ends), and 5D (steel fibers with totally six hooks at both ends) in which the fibers have been located either perpendicular to the crack width or in an inclined manner. The pullout behavior of the mentioned steel fibers at an inclination angle of 0, 15, 30, 45, and 60 degrees and with embedded lengths of 10, 15, 20, 25, and 30 millimetres is studied in order to explore the simultaneous effect of the inclination angle of the fibers relative to the alongside loading and the embedded length of fibers on the pullout response in each case, including the maximal pullout force, the slip of the maximum point of pullout force, pullout energy, fiber rupture, and concrete matrix spalling. The results showed that the maximum pullout energy in 3D, 4D, and 5D steel fibers with different embedded lengths occurs at 0 to 30° inclination angles. In 5D fibers, maximum pullout energy occurs at a 30° angle with a 25 mm embedded length.

• Journal of Korean Physical Therapy Science
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• v.29 no.4
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• pp.65-74
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• 2022

Background: This study attempted to find out the degree of awareness of owners who have the most influence on companion animal's rehabilitation exercise, and the purpose of the treatment effect, and the expectations of rebilitation treatment. The purpose of this study is to find out about the awareness, comprehension, and expectations of caregiver for rehabilitation exercise in companion animal medical services, and to develop them into a field of animal medical services. Design: The tool used in this study used a questionnaire, and the composition consists of the subject's general characteristics, recognition of companion animal rehabilitation, comprehension and expectation. Methods: A questionnaire was given to 103 companion animal's owners, and all were collected and analyzed. Analysis of the frequency analysis method, Fisher's exact test were analyzed. Results: It was confirmed that the difference was significant in the question of whether the caregivers had heard companion animal rehabilitation (p<.05). When asked that rehabilitation is necessary to improve physical function, the difference was confirmed to be significant (p<.05). The significance was confirmed when asked if the caregiver was willing to participate in animal rehabilitation education (p<.05). When asked if caregiver was willing to recommend rehabilitation exercise for companion animal of other caregiver who need rehabilitation exercise, it was confirmed that the difference was significant (p<.05). Conclusion: There was significant difference between gender. This study confirmed that the definite concept caregivers' perception in animal rehabilitation was not established. Therefore, in order to improve perception of caregivers, interdisciplinary exchanges and publicity for animal rehabilitation are needed, and the development of training and education programs for rehabilitation experts was suggested.

• Journal of the Korea Society of Computer and Information
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• v.28 no.5
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• pp.83-93
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• 2023

The purpose of this study is to improve pain and injury through bicycle fitting and to propose rehabilitation methods. Pain and injuries caused by bicycles can be largely divided into knee and ankle pain, wrist, shoulder, neck, and back pain, and hip pain. The cause of these pains and injuries stems from incorrect bicycle fitting and posture. In order to improve these pain and injuries and prevent recurrence, appropriate bicycle fitting and rehabilitation exercise are needed. Pain and injury are divided into kinetic pain and pain by a fixed posture. In the case of kinetic pain, rehabilitation exercise is required along with inflammatory treatment, and pain by a fixed posture should understand the exact characteristics of the body and learn and practice bicycle posture according to the body's characteristics. Through this method, it can contribute to preventing the recurrence of bicycle pain and injuries and further creating an environment where a safe bicycle culture can be established.