• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.10
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• pp.1413-1420
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• 2013

This paper proposes a novel compact MIMO antenna which has miniaturized radiators and their row correlation coefficient, working for the LTE mobile communication, and its SAR is observed. Each of the proposed radiators has a shape of staircase and the bandwidth is twice larger than the conventional PIFA as 600MHz(21%) in 2.5 GHz - 3.15 GHz. And the area of the radiators is $16.5mm{\times}9.7mm$ proper for a handheld device. Also, by adding a planar mushroom decoupling structure between the radiators, the isolation is improved. The design has been carried out using the commercial full-wave time-domain EM solver and the finalized MIMO antenna has the return loss less than -10 dB in the LTE band, the isolation better than 20 dB and the efficiency more than 90% with the gain of 4.3 dB. Regarding the SAR of the antenna, it is observed that the average SAR value of 1g is estimated as 1.37W/Kg, which is lower than the SAR standard.

• Journal of Electrical Engineering and Technology
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• v.10 no.3
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• pp.740-754
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• 2015

This paper focuses on the reverse blocking busbar protection scheme with aim to improve the speed of its operation and at the same time to increase operational reliability, flexibility and stability of the protection during external and internal faults by implementation of the extended functionality provided by the IEC61850 standard-based protective Intelligent Electronic Devices (IEDs). The practical implementation of the scheme by the use of IEC 61850 standard communication protocol is investigated. The proposed scheme is designed for a radial type of a distribution network and is modeled and simulated in the DigSILENT software environment for various faults on the busbar and its outgoing feeders. A laboratory test bench is built using three ABB IEDs 670 series that are compliant with the IEC 61850 standard, CMC 356 Omicron test injection device, PC, MOXA switch, and a DC power supplier. Two types of the reverse blocking signals between the IEDs in the test bench are considered: hard wired and Ethernet communication by using IEC 61850 standard GOOSE messages. Comparative experimental study of the operational trip response speeds of the two implementations for various traffic conditions of the communication network shows that the performance of the protection scheme for the case of Ethernet IEC 61850 standard-based communication is better.

• The KSFM Journal of Fluid Machinery
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• v.11 no.2
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• pp.29-37
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• 2008

Air supply is required to the cathode of fuel cells for the provision of oxygen to produce electricity through chemical reaction with hydrogen in the cell, and supplied air should be free of impurities such as oil mist and tiny particles separated from sliding surfaces. Hence, air compressor for fuel cell air supply must be oil-less type and have no severe sliding surfaces inside. This paper introduces the concept of single-vane type rotary air compressor whose structure is particularly suitable for the fuel cell application: sliding action of the vane against the cylinder wall, which causes severe friction in the conventional vane rotary compressors, is made to be prevented by attaching the vane to the driving shaft with the compliant device between the vane and the rotor in this new design. For 2 kW fuel cell application, preliminary design has been carried out, and its performance has been estimated by using computer simulation program: for discharge pressure of 2 bar, the volumetric, adiabatic, and mechanical efficiencies are calculated to be 82.5%, 92.5%, and 96.3%, respectively.

• The Journal of Korean Physical Therapy
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• v.23 no.3
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• pp.37-42
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• 2011

Purpose: The principal objective of this study was to evaluate the power output of ultrasound in Korean clinics and compare the value with Korean and global standards. Methods: A total of 69 units were measured for ultrasound power output. The normal range of power output level was ${\pm}30%$ of the output set according to KFDA standards. Device model, manufacturer, ERA, and BNR were obtained via simple questionnaires. A portable ultrasound power meter was used for output measurement. Results: 37 machines, with reported ERA values, were assessed for power output per unit area. Of these machines, 13 (37.14%) were considered to be compliant with US FDA standards at 0.5, 1.0, 1.5, $20W/cm^2$ and 18 (51.43%) were considered within KFDA standards. The remainder of the machines were outside the standard error and evidenced irregular output levels, even though most of them were the same model. Conclusion: Appropriate ultrasound intensity is incredibly important for safety and effective use. Therefore, the KFDA standards regarding ultrasound may require revision in light of global standards, including BNR and ERA additionally, attention should be paid to regular calibration for safe use in clinical practice.

• Journal of Advanced Navigation Technology
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• v.22 no.5
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• pp.472-477
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• 2018

In this paper, we develop interactive content services for preventing depression of users through an intelligent Internet of Things(IoT) mirror system. For interactive content services, an IoT mirror device measures attention and meditation data from an EEG headset device and also measures facial expression data such as "sad", "angery", "disgust", "neutral", " happy", and "surprise" classified by a multi-layer perceptron algorithm through an webcam. Then, it sends the measured data to an oneM2M-compliant IoT server. Based on the collected data in the IoT server, a machine learning model is built to classify three levels of depression (RED, YELLOW, and GREEN) given by a proposed merge labeling method. It was verified that the k-nearest neighbor (k-NN) model could achieve about 93% of accuracy by experimental results. In addition, according to the classified level, a social network service agent sent a corresponding alert message to the family, friends and social workers. Thus, we were able to provide an interactive content service between users and caregivers.

• Journal of Communications and Networks
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• v.13 no.5
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• pp.518-524
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• 2011

A high assurance IP encryption (HAIPE) compliant protocol accelerator is proposed for military networks consisting of red (or classified) networks and black (or unclassified) networks. The boundary between red and black sides is assumed to be protected via a HAIPE device. However, the IP layer encryption introduces challenges for bandwidth on demand satellite communication. The problems experienced by transmission control protocol (TCP) over satellites are well understood: While standard modems (on the black side) employ TCP performance enhancing proxy (PEP) which has been shown to work well, the HAIPE encryption of TCP headers renders the onboard modem's PEP ineffective. This is attributed to the fact that under the bandwidth-on-demand environment, PEP must use traditional TCP mechanisms such as slow start to probe for the available bandwidth of the link (which eliminates the usefulness of the PEP). Most implementations recommend disabling the PEP when a HAIPE device is used. In this paper, we propose a novel solution, namely broadband HAIPE-embeddable satellite communications terminal (BHeST), which utilizes dynamic network performance enhancement algorithms for high latency bandwidth-on-demand satellite links protected by HAIPE. By moving the PEP into the red network and exploiting the explicit congestion notification bypass mechanism allowed by the latest HAIPE standard, we have been able to regain PEP's desired network enhancement that was lost due to HAIPE encryption (even though the idea of deploying PEP at the modem side is not new). Our BHeST solution employs direct video broadcast-return channel service (DVB-RCS), an open standard as a means of providing bandwidth-on-demand satellite links. Another issue we address is the estimation of current satellite bandwidth allocated to a remote terminal which is not available in DVBRCS. Simulation results show that the improvement of our solution over FIX PEP is significant and could reach up to 100%. The improvement over the original TCP is even more (up to 500% for certain configurations).

• The Journal of the Korea Contents Association
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• v.12 no.8
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• pp.77-86
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• 2012

Avionics system are composed of multiple electronic device that performs important missions the number of electronic devices for the performance of aircraft has been gradually increasing. As a result, cost of development, maintenance and operating have increased. To solve this problem, technology paradigm of avionics has been shifting from federated avionics systems that manage to each system independently to IMA(Integrated Modular Avionics) systems. Unlike federated systems, fault tolerance becomes an essential technology in IMA systems. Because each aircraft features integrated in the an IMA system, a fault can jeopardize the entire system. In this paper, we define faults which can occur on the ARINC 653 based IMA system first, and design the ARINC 653 compliant HM(health Monitoring) system for the system can continue to operate be normal when occur a fault.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.7
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• pp.969-975
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• 2018

The purpose of this study is to develop a healthcare service based on standard protocol and information communication technology for mother's sustainable postpartum care. The developed service was consisted of a client area where mothers measure, manage and transmit their vital signs using their own smartphone and personal health devices, and a server area that manages and shares with the received mother's vital signs and the results of examination results and personal health records. The client area collects vital signs through the IEEE 11073 Personal Health Device (PHD) using the m-health application of the previous study and Continua Health alliance certified personal health devices and transfers to Health Level Seven (HL7) V2.4, Continuity of Care Record (CCR) and Continuity of Care Document (CCD). The server area consists of a mobile web that manages and shares the HL7 Fast Healthcare Interoperability Resources (FHIR)-compliant personal health records to ensure interoperability of examination results, and a mobile web where the postpartum caregiver enters and manages the results of the mother's examination results and provides it to the mother. In this way, the healthcare service of this study securing continued exchanges between the mother and postpartum caregiver improves the quality of life of the mother not only to satisfy the needs of the mother who was discharged but also through self-management and postpartum. In the future, we will conduct a study applying mothers and postpartum caregiver after approval of a clinical trail at a university hospital to evaluate developed healthcare services.

• Journal of Digital Contents Society
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• v.19 no.9
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• pp.1819-1824
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• 2018

This paper proposes a control method of ASMR(autonomous sensory meridian response) contents to relieve user's stress and improve his attention. The proposed method measures EEG(electroencephalography), attention, meditation, and eyeblink data from an EEG device and sends them to an oneM2M-compliant IoT(internet of things) server platform through an Android IoT Application. Then a SVM(support vector machine) model is built to classify user's mental health status by using EEG, attention and meditation data collected in the server platform. The ASMR contents are controlled by the mental health status classified by a SVM model and the eyeblink data. When comparing the SVM models according to types of data used, the SVM model with attention and meditation data showed accuracy of 85.7%. It was verified that the proposed control algorithm of ASMR contents properly worked as the mental health status from the SVM model and the eyeblink data changed.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.10a
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• pp.348-353
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• 2008

Despite the increasing popularity of wireless sensor network, indoor positioning using low power IEEE 802.15.4 compliant radio had attracted an interest of many researchers in the last decade. Old fashionable indoor location sensing information has been presented in dull and unpleasant 2D image standard. This paper focused on visualizing high precision 3 dimensional RSSI-based (received signal strength indication) spatial sensing information in an interactive virtual reality on PDA. The developed system operates by capturing and extracting signal strength information at multiple pre-defined reference nodes to provide information in the area of interest, thus updating user's location in 3D indoor virtual map. VRML (Virtual Reality Modeling Language) which specifically developed for 3D objects modeling is utilized to design 3D indoor environment.