• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.7
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• pp.153-161
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• 2015

In the present study, as part of the technology development (Quality of Life Technology, QoLT) to improve the socio-economic status of people with disabilities as an extension of these studies, we propose the development of the smart wheelchair system and navigation technology for stable and safe driving in various environments. For the disabled and the elderly make driving easy and convenient with manual/autonomous driving condition, we firstly develop the user-oriented smart wheelchair system with optimized sensors for environment recognition, and then we propose a navigation framework of a hierarchical structure to ensure real-time response, as well as driving stability when traveling to various environmental changes, and to enable a more efficient operation. From the result of several independent experiments, we ensure efficiency and safety of smart wheelchair and its navigation system.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.15 no.1
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• pp.14-26
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• 2022

Recently, according to the severity of air pollution, interest in air pollution is increasing. The IoT based fine dust monitoring system proposed in this paper allows the measurement and monitoring of fine dust, volatile organic compounds, carbon dioxide, etc., which are the biggest causes affecting the human body among air environmental pollution. The proposed system consisted of a device that measures atmospheric environment information, a server system for storing and analyzing measured information, an integrated monitoring management system for administrators and smart phone applications for users to enable visualization analysis of atmospheric environment information in real time. In addition, the effectiveness of the proposed fine dust monitoring system based on the Internet of Things was verified by using the response speed of the system, the transmission speed of the sensor data, and the measurement error of the sensor. The fine dust monitoring system based on the Internet of Things proposed in this paper is expected to increase user convenience and efficiency of the system by visualizing the air pollution condition after measuring the air environment information with portable fine dust measuring device.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.11
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• pp.1596-1602
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• 2021

Battery-operated IoT devices in IoT systems require low power consumption. In general, IoT devices enter a sleep state synchronously to reduce power consumption. A problem arises when an IoT device has to handle asynchronous user requests, as the duty cycle must be reduced to enhance response time. In this paper, we propose a new low-power-consumption scheme, called Repetitive Wake-up scheme for IoT systems of asynchronous environments such as indoor lights control. The proposed scheme can reduce power consumption by sending wake-up signals from the smartphone repetitively and by retaining the IoT device in sleep state to the smallest possible duty cycle. In the various environments with IoT devices at home or office space, we showed that the proposed scheme can reduce power consumption by up to five times compared to the existing synchronous interlocking technique.

• Journal of the Korea Society of Computer and Information
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• v.14 no.10
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• pp.189-197
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• 2009

As the web service technology matures. research is focused on the composite web services that combine individual web services within an enterprise or between enterprises. Quality of service is the critical competitiveness factor in this mature technology stage where there are many services with similar functionalities differing only in some non-functional properties. Monitoring is the key component for the service quality management of a web service. A service quality monitoring system design using a broker is presented in this paper. OWL-S is used to specify the composite service process and a service policy (inputs and outputs of each service, quality attributes and values, etc.) built by WS-Policy is applied to the composite service process. If there is any discrepancy between the service policy and the monitored data, the service provider and the user are notified of it so as to take necessary measures. We have implemented a travel reservation system as an example of the presented design and the experimental results are shown. Average response time was monitored and the timeout policy was applied in the experiment.

• KIPS Transactions on Computer and Communication Systems
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• v.12 no.11
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• pp.337-346
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• 2023

There is a need to develop an app for a caregiver health management that can provide continuous management in response to changes over time, because elderly people have low digital utilization capabilities, difficulty maintaining regular and continuous self-management. Based on this need, this study designed an app with a user-friendly UI and simple structure for the elderly. The app developed in this study supports regular management of health data such as blood pressure, blood sugar, and heart rate, as well as specific information on physical, disease, cognitive, communication, and environment in the care field. The app developed in this study supports care services by automatically entering data through integration with health management devices, automatically analyzing and visually representing recorded data to understand trends and volatility, and adding scalability to connect with various health management and medical support platforms. The effectiveness and satisfaction of the developed app were confirmed to be significant in the field verification results.

• Journal of Digital Contents Society
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• v.17 no.6
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• pp.581-592
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• 2016

WebRTC has quickly grown to be the world's advanced real-time communication in several platforms such as web and mobile. In spite of the advantage, the current technology in WebRTC does not handle a big-streaming efficiently between peers and a large amount request of users on the Signaling server. Therefore, in this paper, we put our work to handle the problem by delivering the flow of data with dynamical load balancing algorithms. We analyze the request source users and direct those streaming requests to a load balancing component. More specifically, the component determines an amount of the requested resource and available resource on the response server, then it delivers streaming data to the requesting user parallel or alternately. To show how the method works, we firstly demonstrate the load-balancing algorithm by using a network simulation tool OPNET, then, we seek to implement the method into an Ubuntu server. In addition, we compare the result of our work and the original implementation of WebRTC, it shows that the method performs efficiently and dynamically than the origin.

• Journal of Preventive Medicine and Public Health
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• v.31 no.4 s.63
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• pp.628-643
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• 1998

To investigate the exposure levels of organic solvents and subjective symptoms of dry-cleaning workers, 77 male and 52 female dry-cleaning workers who had been worked in a small city of Chungnam province, and a large city, Taejon were selected for the study group. Air concentrations of organic solvents in the working environment were analyzed, and subjective symptoms of dry-cleaning workers were surveyed, from July to August 1996. The results obtained were as follows : 1. The concentrations of organic solvents in the working environment were within permissible TLV-TWA limits. 2. For the 13 symptom clusters, the most frequently complained symptom clusters were fatigue as 71.3%, and followed by depression and urinary disturbances as 53.5% and 51.9%. Other symptom clusters complained were below 50%. 3. Positive response rates of subjective symptoms were significantly higher in worker groups such as lived in a large city, female, higher education level, more frequently alcohol drinking, higher concentration of organic solvent in working environment, work in alone. 4. Workers who had used solvent B showed 2.3 point higher scores of subjective symptoms than those of solvent A. Of the subjective symptoms scores, amnesia and nervousness were higher in solvent B user group than solvent B user group. 5. As a result of factor analysis, 3 factors such as depression, urinary disturbance and neurologic disturbance were selected. 6. As a result of the logistic regression analysis, sex, the number of fellow workers, working time, region, job tenure, smoking, alcohol drinking, ventilating system, concentration of organic solvent in working environment and place of residence were selected for the related variables. For the conclusion, even though the concentrations of organic solvents in the working environments of dry-cleaning workers were within permissible limit of TLV-TWA, many dry-cleaning workers complained symptoms, such as fatigue, depression, urinary disturbances and so on. And the factors affecting to the symptoms of dry-cleaning workers were the number of fellow workers, work hours, region, job tenure, smoking and alcohol drinking.

• KIPS Transactions on Computer and Communication Systems
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• v.6 no.10
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• pp.429-436
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• 2017

There is a growing tendency to outsource sensitive or important data in cloud computing recently. However, it is very important to protect the privacy of outsourced data. So far, a variety of secure and efficient multi-keyword search schemes have been proposed in cloud computing environment composed of a single data owner and multiple data users. Zhang et. al recently proposed a search protocol based on multi-keyword in cloud computing composed of multiple data owners and data users but their protocol has two problems. One is that the cloud server can illegally infer the relevance between data files by going through the keyword index and user's trapdoor, and the other is that the response for the user's request is delayed because the cloud server has to execute complicated operations as many times as the size of the keyword index. In this paper, we propose an improved multi-keyword based search protocol which protects the privacy of outsourced data under the assumption that the cloud server is completely unreliable. And our experiments show that the proposed protocol is more secure in terms of relevance inference between the data files and has higher efficiency in terms of processing time than Zhang's one.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.3
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• pp.89-97
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• 2012

In recent years, efficient energy management technologies are required, as environmental problems have emerged worldwide. In response to this, smart home services focused on efficient energy management technology seems to be emerging. And the integration of technology of user-oriented real-time energy monitoring and control systems is required. In this paper, we present a location-based green home service using smart phones for efficient energy management in a house. We design a green home network system to apply the green home service, and implement an integrated gateway system which connects and controls each appliance in a house. We develop appliance control services and indoor location services on smart phones, and determine whether user's occupancy of each room by measuring the location according to the variation of signal strength. In order to evaluate the performance of the energy savings, we have set up the scenarios of energy usage pattern and have compared the energy variation resulting from the application of the indoor location services with smart meters. A comparison of energy usage demonstrated that the energy saving of a house with the proposed location-based green home service was down up to 30%.

• The KIPS Transactions:PartD
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• v.10D no.1
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• pp.1-12
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• 2003

Recently, there have been many indexing schemes for multimedia data such as image, video data. But recent database applications, for example data mining and multimedia database, are required to support multi-user environment. In order for indexing schemes to be useful in multi-user environment, a concurrency control algorithm is required to handle it. So we propose a concurrency control algorithm that can be applied to CBF (cell-based filtering method), which uses the signature of the cell for alleviating the dimensional curse problem. In addition, we extend the SHORE storage system of Wisconsin university in order to handle high-dimensional data. This extended SHORE storage system provides conventional storage manager functions, guarantees the integrity of high-dimensional data and is flexible to the large scale of feature vectors for preventing the usage of large main memory. Finally, we implement the web-based image retrieval system by using the extended SHORE storage system. The key feature of this system is platform-independent access to the high-dimensional data as well as functionality of efficient content-based queries. Lastly. We evaluate an average response time of point query, range query and k-nearest query in terms of the number of threads.