• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권9호
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• pp.3357-3376
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• 2015

Wireless sensor network is an important research topic that has attracted a lot of attention in recent years. However, most of the interest has focused on wireless sensor network to gather scalar data such as temperature, humidity and vibration. Scalar data are insufficient for diverse applications such as video surveillance, target recognition and traffic monitoring. However, if we use camera sensors in wireless sensor network to collect video data which are vast in information, they can provide important visual information. Video sensor networks continue to gain interest due to their ability to collect video information for a wide range of applications in the past few years. However, how to efficiently store the massive data that reflect environmental state of different times in video sensor network and how to quickly search interested information from them are challenging issues in current research, especially when the sensor network environment is complicated. Therefore, in this paper, we propose a fast algorithm for extracting key frames from video and describe the design and implementation of key frame extraction and sharing in Android for wireless video sensor network.

• Journal of Positioning, Navigation, and Timing
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• 제13권1호
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• pp.25-34
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• 2024

The Satellite Based Augmentation System (SBAS) improves the accuracy and reliability of user positioning by transmitting the error correction and integrity information of the global navigation satellite system signal from geostationary satellites in real time. For this reason, SBAS was designed for aircraft operations and approach procedures and is now in operational or development stages in many countries. Time has passed since the construction of SBAS and many changes have occurred in the composition of the monitoring stations and the geostationary satellites. These changes have been investigated and the current operation and development status of SBAS globally are surveyed. The development and test schedules for the transition to dual frequency multi-constellation, an important topic in SBAS, are discussed.

• 정보과학회 컴퓨팅의 실제 논문지
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• 제21권12호
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• pp.768-773
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• 2015

사회적 혼란을 야기하는 이벤트는 발생 직후 어떻게 대응하느냐에 따라 소요되는 비용의 편차가 크다. 이에 따라 비정상적인 이벤트를 탐지하고 의미를 파악하는 연구가 많이 진행되고 있다. 또한 예측 분석에 관한 연구도 많이 수행되고 있다. 그러나 대부분의 연구는 이벤트의 전체적인 미래 경향에 대한 수치 결과를 예측할 뿐, 이벤트가 내포하는 의미에 대한 예측 연구는 미비하다. 이에 따라 본 논문에서는 비정상적인 이벤트가 내포하는 토픽의 조합을 통해 미래에 어떠한 일이 발생할 수 있는지에 대한 시각적 예측 분석 방법을 제안한다. 제안하는 방법은 먼저 트윗에서 실시간으로 비정상 이벤트를 탐지한다. 그 다음 과거 유사한 사례를 탐색한 다음 이벤트와 관련된 토픽들을 추출한다. 마지막으로 사용자는 의미 있는 토픽의 조합을 통해 미래에 어떠한 일이 발생할 수 있을지 분석할 수 있다. 실험은 두 가지 상황에 대한 예측 분석을 수행하였으며, 실험 결과 본 논문에서 제안한 방법의 타당성을 입증하였다.

• 한국콘텐츠학회논문지
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• 제21권4호
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• pp.1-13
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• 2021

코로나19에 대한 전세계적 팬데믹이 진행되고 있는 상황에서 잘못된 정보가 대중에게 노출되었을 경우 발생할 수 있는 잠재적인 문제에 대한 우려와 함께 현재 주요 앱 마켓에서 민간 애플리케이션에 대한 차단 조치도 단행되고 있다. 그러나 감염병 상황에서 중앙집중식의 일방적인 정보 전달보다 대중이 스스로 정보를 공유하는 것이 효과적인 측면도 동시에 존재한다. 본 연구는 텍스트마이닝을 이용해 감염병 상황에서 민간 주도의 정보제공에 대한 이용자 반응을 분석한다. 이를 위해 정부와 민간이 현재 한국의 구글 플레이스토어에서 제공하고 있는 모든 코로나19 애플리케이션에 대한 이용자들의 반응에 대한 토픽 모델링과 감성분석을 실시한다. 분석 결과, 이용자들은 정보의 신뢰성, 위험회피, 실시간성, 유용성, 안정성 등 모든 차원에서 정부 대비 민간 애플리케이션에 대해 더 긍정적인 반응을 보이는 것으로 분석되었다. 분석 결과를 바탕으로 민간 애플리케이션에 대한 일방적인 차단이 아닌, 사후적인 모니터링 시스템을 도입하는 방안 등을 제안한다.

• Structural Engineering and Mechanics
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• 제86권6호
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• pp.715-730
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• 2023

Broad studies have addressed the issue of structural element damage identification, however, rubber bearing, as a key component of load transmission between the superstructure and substructure, is essential to the operational safety of a bridge, which should be paid more attention to its health condition. However, regarding the limitations of the traditional bearing damage detection methods as well as few studies have been conducted on this topic, in this paper, inspired by the model updating-based structural damage identification, a two-stage bearing damage identification method has been proposed. In the first stage, we deduce a novel bearing damage localization indicator, called element relative MSE, to accurately determine the bearing damage location. In the second one, the prior knowledge of bearing damage localization is combined with sailfish optimization (SFO) to perform the bearing damage estimation. In order to validate the feasibility, a numerical example of a 5-span continuous beam is introduced, also the noise robustness has been investigated. Meanwhile, the effectiveness and engineering applicability are further verified based on an experimental simply supported beam and actual engineering of the I-40 Bridge. The obtained results are good, which indicate that the proposed method is not only suitable for simple structures but also can accurately locate the bearing damage site and identify its severity for complex structure. To summarize, the proposed method provides a good guideline for the issue of bridge bearing detection, which could be used to reduce the difficulty of the traditional bearing failure detection approach, further saving labor costs and economic expenses.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2013년도 추계학술대회 논문집
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• pp.63-64
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• 2013

Induction motors' faults detection is almost a popular topic among researchers. Monitoring the output of motors is a key factor in detecting these faults. (Short-time) Fourier, (continuous, discrete) wavelet, and extended Park vector transformations are among the methods for fault detection. One major deficiency of these methods is not being able to detect the severity of faults that carry low energy information, e.g. in ball bearing system failure, there is absolutely no way to detect the severity of fault using Fourier or wavelet transformations. In this paper, the authors have applied the Discrete Wavelet Transform (DWT) frequency-domain analysis to detect bearing faults in an induction motor. In other words, in discrete transform which the output signal is decomposed in several steps and frequency resolution increases considerably, the frequency-band analysis is performed and it will be verified that first of all, fault sidebands become more recognizable for detection in higher levels of decomposition, and secondly, the inner race bearing faults turn out easier in these levels; and all these matter because of eliminating the not-required high energy components in lower levels of decomposing.

• International Journal of Aeronautical and Space Sciences
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• 제17권4호
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• pp.535-550
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• 2016

Securing the safety and the reliability of liquid-propellant rocket engines (LREs) for space vehicles is indispensable as engines consist of many complex components and operate under extremely high energy-dense conditions. Thus, health monitoring has become a mandatory requirement, especially for the reusable LREs that are currently being developed. In this context, a dynamic simulation program based on MATLAB/Simulink was developed in the current research on the Space Shuttle Main Engine (SSME), a partly reusable engine. Then, a series of fault simulations using this program was conducted: at a steady state operating condition (104% Rated Propulsion Level), various simulated fault conditions were artificially injected into the simulation models for the five major valves, the pumps, and the turbines of the SSME. The consequent effects due to each fault were analyzed based on the time responses of the major parameters of the engine. It is believed that this research topic is an essential pre-step for the development of fault detection and diagnosis algorithms for reusable engines in the future.

• 지식경영연구
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• 제16권4호
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• pp.35-45
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• 2015

Fintech, which means the convergence of finance and information technology, becomes a hot topic in the financial sector. Through innovative activities on financial services, ICT(Information and Communication Technology) is integrated into the overall financial industry, and a new form of financial services could be expected to improve the existing financial system. On the other hand, fintech services are relatively vulnerable to security issues. Due to the process simplication and the channel fusion, the leakage of personal and financial informations, authentication bypass, phishing, and pharming are getting more concerned. In this study we investigated the security risk of fintech services in the viewpoints of service provider, technology adoption, and security policy. The possible countermeasures to reduce those risks are suggested because security is an important criterion for selecting financial services. This study basically offers quantification of the potential security risks and step-by-step control measures about business processes in the fintech services. The suggested security model includes user authentication, terminal security, payment information protection, API(Application Programming Interface) security, and abnormal transaction monitoring. This study might contribute to an understanding of the security risks and some possible measures for mitigating those risks on the practical perspective.

• 한국학교ㆍ지역보건교육학회지
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• 제14권2호
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• pp.59-73
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• 2013

Objectives: Health promotion policies have been developed and implemented in most developed countries. The purpose of this study is to compare the national health promotion plans among Korea, Japan and USA. Methods: Data were collected and involved overview of health promotion plans, formulation of policy, evaluation, monitoring and research, implementation in each countries. I got the some literatures over the governmental websites related to the health promotion. The data from each country were analyzed for comparison. Results: The goals of Healthy People 2020 are to attain high-quality, longer lives, to achieve health equity, to create social and physical environments, to promote quality of life across all life stages. Those of Healthy Japan 21 are increasing the year of healthy life and reducing health disparities. and Those of Health Plan 2020 are prolonging of healthy age and improvement of healthy equity. The number of topic areas and objectives of health promotion in each countries were different. Healthy People 2020 lacks participation of community people and stakeholders in the process of planning, impletation, evaluation. Conclusion: The planning models of health promotion were different among countries. But they reflect the social determinants of health. The health plan goals of Korea were similar to Japan. but were different from USA. The implementation and evaluation systems of USA and Japan were systematic and performed well than those of Korea.

• Tuberculosis and Respiratory Diseases
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• 제80권3호
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• pp.230-240
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• 2017

Chronic obstructive pulmonary disease (COPD) results in high morbidity and mortality among patients both domestically and globally. The Korean clinical practice guideline for COPD was revised in 2014. It was drafted by the members of the Korean Academy of Tuberculosis and Respiratory Diseases, as well as participating members of the Health Insurance Review and Assessment Service, Korean Physicians' Association, and Korea Respiration Trouble Association. This revised guideline covers a wide range of topics, including the epidemiology, diagnosis, assessment, monitoring, management, exacerbation, and comorbidities of COPD in Korea. We drafted a guideline on COPD management by performing systematic reviews on the topic of management with the help of a meta-analysis expert. We expect this guideline will be helpful medical doctors treating patients with respiratory conditions, other health care professionals, and government personnel in South Korea.