• Journal of information and communication convergence engineering
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• 제21권3호
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• pp.185-191
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• 2023

The Internet of Things (IoT) can be defined as the connection of devices, sensors, and actors via the Internet to a single network to provide services to end-users. Owing to the flexibility and simplicity of IoT devices, which impart convenience to end-users, the demand for these devices has increased significantly in the last decade. To make these systems more scalable, achieve a larger number of connected devices, and achieve greater economic success, it is vital to develop them by considering parameters such as security, cost, bandwidth, data rate, and power consumption. This study aims to improve energy efficiency and prolong the lifetime of IoT networks by proposing a new approach called the constrained application protocol CoAP45. This approach reduces the number of updates to the CoAP server using a centralized resource. The simulation results show that the proposed approach outperforms all existing protocols.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2008년도 한국컴퓨터종합학술대회논문집 Vol.35 No.1 (D)
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• pp.476-479
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• 2008

Wireless Sensor Network typically incorporates various real time applications that must meet timing constraints under severe resource limitations. Due to the high data rate and burst traffic for that type of applications, occurrence of congestion is very common. Ensuring the end-to-end deadline under congested scenario is quite challenging. In this paper we propose a hop-by-hop rate control algorithm which avoids the congestion as well as ensures that the real time traffic will meet the end-to-end deadline by guaranteeing the meeting of local deadline at intermediate hop. Finally, simulation has demonstrated the effectiveness of our approach.

• 대한치과의사협회지
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• 제55권8호
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• pp.556-564
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• 2017

Endodontic surgery is a procedure to treat apical periodontitis or abscess in cases that did not heal after nonsurgical treatment or retreatment. This might include situations with persistent intracanal infection after root canal treatment. Other reasons might be found in extraradicular infection, such as bacterial biofilm on the apical root surface or bacteria within the lesion. For many years, the treatment standard was the traditional approach with surgical burs and amalgam for root-end filling. Endodontic microsurgery is the most recent step in the evolution of endodontic surgery, applying not only ultrasonic tip and biocompatible filling materials but also incorporating high-power magnification and illumination. Although many studies have been published that advocate the use of modern technique, the traditional techniques are still widely used in the surgery community. The purpose of this study was to demonstrate the endodontic microsurgery procedure including the root-end preparation and filling with the use of a surgical operating microscope.

• Journal of Computing Science and Engineering
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• 제9권3호
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• pp.142-154
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• 2015

Fault localization techniques help locate faults in source codes by exploiting collected test information and have shown promising results. To precisely locate faults, the techniques require a large number of test cases that sufficiently exercise the executable statements together with the label information of each test case as a failure or a success. However, during the process of software development, developers may not have high-coverage test cases to effectively locate faults. With the test case generation techniques, a large number of test cases without expected outputs can be automatically generated. Whereas the execution results for generated test cases need to be inspected by developers, which brings much manual effort and potentially hampers fault-localization effectiveness. To address this problem, this paper presents a method to select a few test cases from a number of test cases without expected outputs for result inspection, and in the meantime selected test cases can still support effective fault localization. The experimental results show that our approach can significantly reduce the number of test cases that need to be inspected by developers and the effectiveness of fault localization techniques is close to that of whole test cases.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권2호
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• pp.618-633
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• 2014

Relay technology is becoming more important for mobile communications and wireless internet of things (IoT) networking because of the extended access network coverage range and reliable quality of service (QoS) it can provide at low power consumption levels. Existing mobile multihop relay (MMR) technology uses fixed-point stationary relay stations (RSs) and a divided time-frame (or frequency-band) to support the relay operation. This approach has limitations when a local fixed-point stationary RS does not exist. In addition, since the time-frame (or frequency-band) channel resources are pre-divided for the relay operation, there is no way to achieve high channel utilization using intelligent opportunistic techniques. In this paper, a different approach is considered, where the use of mobile/IoT devices as RSs is considered. In applications that use mobile/IoT devices as relay systems, due to the very limited battery energy of a mobile/IoT device and unequal channel conditions to and from the RS, both minimum energy consumption and QoS support must be considered simultaneously in the selection and configuration of RSs. Therefore, in this paper, a mobile RS is selected and configured with the objective of minimizing power consumption while satisfying end-to-end data rate and bit error rate (BER) requirements. For the RS, both downlink (DL) to the destination system (DS) (i.e., IoT device or user equipment (UE)) and uplink (UL) to the base station (BS) need to be adaptively configured (using adaptive modulation and power control) to minimize power consumption while satisfying the end-to-end QoS constraints. This paper proposes a minimum transmission power consuming RS selection and configuration (MPRSC) scheme, where the RS uses cognitive radio (CR) sub-channels when communicating with the DS, and therefore the scheme is named MPRSC-CR. The proposed MPRSC-CR scheme is activated when a DS moves out of the BS's QoS supportive coverage range. In this case, data transmissions between the RS and BS use the assigned primary channel that the DS had been using, and data transmissions between the RS and DS use CR sub-channels. The simulation results demonstrate that the proposed MPRSC-CR scheme extends the coverage range of the BS and minimizes the power consumption of the RS through optimal selection and configuration of a RS.

• 제어로봇시스템학회논문지
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• 제2권1호
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• pp.35-44
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• 1996

A design method for a teleoperator robot system is presented in this paper. The control system consists of two phases; approach phase and contact one. The end-effector position of the estimated slave robot and the contact force between the end-effector and wall are displayed on the monitors at control site, using which the operator controls the teleoperator system. The approach phase controller is designed using Smith's principle and the contact one designed based upon the structured singular value ${\mu}$ in order to increase the robustness of the system. The uncertainatices such as communication time delay and the variations of system parameters are considered as a muliplicative pertubation. Computer simulations are conducted in order to evaluate the performance of the proposed design method. It is found that desirable control performance, especially in the contact phase, is obtained if the control mode is switched into contact phase when the estimated position of the slave robot end-effector is in front of the wall.

• 성인간호학회지
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• 제29권2호
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• pp.119-130
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• 2017

Purpose: The purpose of this study was to understand the nurses' experiences of end of life care of older adults with dementia living in long-term care hospitals and geriatric care facilities. Methods: The participants were nine nurses. Open in-depth interviews were used to collect data from June, 2016 to November, 2016. Colaizzi's phenomenological approach was used to analyze the data. Results: Three categories were identified. The nurses' reported experiences of end of life care of older adults with dementia were 'warm care with living together', 'care for family', and the 'self-reflection and responsibility as a nurse'. There were ten clusters of themes and 24 themes. The participants stated that the end of life care of older adults with dementia were individualized holistic care with dignity, being in older adults with dementia and family, and responsibility as a professional. Nurses reported the need for dementia hospice care. Conclusion: These results could be considered in planning nursing intervention for hospice care. The findings support the need for educational strategies and programs to improve end of life care among older adults with dementia.

• 한국정보통신학회논문지
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• 제8권2호
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• pp.449-455
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• 2004

본 논문에서는 입력 정합(input matching) BIST(Built-In Self-Test, 자체내부검사) 회로를 이용한 RF front end(고주파 전단부)의 새로운 결함 검사방법을 제안한다. 자체내부검사 회로를 가진 고주파 전단부는 1.8GHz LNA(Low Noise Amplifier, 저 잡음 증폭기)와 이중 대칭 구조의 Gilbert 셀 믹서로 구성되어 있으며, TSMC 40.25{\mu}m$ CMOS 기술을 이용하여 설계되었다. catastrophic 결함(거폭 결함) 및 parametric 변동 (미세 결함)을 가진 고주파 전단부와 결함을 갖지 않은 고주파 전단부를 판별하기 위해 고주파 전단부의 입력 전압특성을 조사하였다. 본 검사방법에서는 DUT(Device Under Test, 검사대상이 되는 소자)와 자체내부검사회로가 동일한 칩 상에 설계되어 있기 때문에 측정할 때 단지 디지털 전압계와 고주파 전압 발생기만 필요하며, 측정이 간단하고 비용이 저렴하다는 장점이 있다.

• 한국ITS학회 논문지
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• 제13권2호
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• pp.80-89
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• 2014

본 논문에서는 최종 사용자의 프로파일(profile), 물의 종류 및 네트워크 상태를 고려한 미래의 스마트 워터 그리드에서의 물의 분배를 위한 컨텍스트 인지 추천시스템을 제안한다. 수자원에 대한 최종 사용자의 공통적인 관심사를 근거로 최종 사용자를 각각 다른 공동체로 군집화하기 위한 스펙트럴 군집화 방안을 개발하였다. 수자원에 대한 최종 사용자의 선호도 평가 목록을 얻기 위한 역전파 신경망을 도입하여 설계하였다. 본 방식은 예상 평가가 가장 높은 수자원을 최종 사용자에게 추천토록 하였다. 시뮬레이션의 결과는 제안된 방식이 기존의 추천 방안에 비하여 보다 나은 사용자의 경험을 바탕으로, 추천의 정확도(오차 2.5%이내)를 상당히 개선시킬 수 있음을 보여주었다.

• Journal of Advanced Marine Engineering and Technology
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• 제18권4호
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• pp.25-32
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• 1994

This paper presents a robust impedance controller design to coordinate a robot manipulator under system uncertainties while regulating external forces. By an impedance approach, the relationship between the motion and external forces is defined. Due to the system uncertainties, two kind of sliding mode control schemes based on the impedance approach are derived to ensure that the manipulator end-effector follows a desired trajectory and the force applied to end effector is regulated according to a target impendance. A stability condition is shown according to a sliding condition. To evaluate the devised control scheme, a numerical example is shown.