• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.12
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• pp.77-86
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• 2020

Power quality problems caused by feeder voltage drop and extension construction cost problems can occur with the increasing utilization rates of the existing fixed-type EV (electric vehicle) charger. Moreover, EV users might not be able to access the EV charger due to a lack of EV charging facilities. Therefore, this paper proposes an MPSD (movable power supply device) for EVs to overcome user inconvenience caused by the insufficient number of chargers and extension cost issues. The proposed MPSD was mainly composed of a PV (photovoltaic) system, ESS (energy storage system), EV charging system, and monitoring and control system. Furthermore, there are three operation modes available to enhance the flexibility of the MPSD application, depending on the situation. This paper also presents an economical evaluation modeling using the present worth method to consider the cost and benefit elements. The simulation results based on proposed modeling showed that MPSD is more economical than the existing EV charger. Moreover, its profit can be increased significantly depending on the distance to the installation point.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.7 no.3
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• pp.49-56
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• 1993

This paper describes design and implementation of signal transmission system using LCX as communication media, which has characteristics of high reliability easy for expansion and complex transmission of voice, data and video signal in Electric culvert. In this system, we estimated system performance as result of variable transmission characteristics test. In case of voice signal, transmission loss characteristics improved 5-10(dB] than designed Values in received signal level. In the test of speech quality estimation, we obtained satisfactory result as speech intensity = 3 (QSA value), speech atriculation = 4 (QRK value). As for data and video signal transmission, communication success rates were 981% 1 in monitoring and control functional test. As a result of transmission characteristics test in transmission line and system, transmission range by LCX communication system without repeater can reach in 6Km. This paper presents basic construction method using LCX communication system for total management in Electric culvert.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.44 no.6
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• pp.29-34
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• 2007

It is important to analyse the frequency spectrum for the measurement of modulated signal, distortion, and noise. The frequency spectrum analysis is performed by the execution of Radix-2 DIT DFT i.e. FFT algorithm. The discrete input signal converted by A/D converter from the input signal in time domain is mathematically transformed to the frequency spectrum by FFT algorithm. In this study, we design the digital spectrum analyser by the hardware based on the TMS320F2812 DSP and AD9244 converter, and by the software based on the C28x S/W modules. We can timely analyse the frequency spectrum in mobile communication system by the digital frequency analyser based on the high performance DSP and S/W modules. This real-time analysing capability is the important performance in the internet-based mobile communication server system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.3
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• pp.40-45
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• 2018

Intelligent monitoring and diagnosis of production processes based on multivariate statistical methods has been one of important tasks for safety and quality issues. This is due to the fact that faults and unexpected events may have serious impacts on the operation of processes. This study proposes a diagnostic scheme based on effective representation of process measurement data and is evaluated using simulation process data. The effects of utilizing a preprocessing step and nonlinear statistical methods are also tested using fifteen faults of the simulation process. Results show that the proposed scheme produced more reliable results and outperformed other tested schemes with none of the filtering step and nonlinear methods. The proposed scheme is expected to be robust to process noises and easy to develop due to the lack of required rigorous mathematical process models or expert knowledge.

• The KIPS Transactions:PartA
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• v.10A no.6
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• pp.651-656
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• 2003

Emerging technologies, such as multimedia and mobile computing, require that middleware platforms can support high adaptability in order to provide more flexible services in heterogeneous environments. To support high quality of service in distributed wired/wireless environments, it will be necessary for applications and middleware to be aware of changes in users requirements as well as environmental conditions, also to be able to adapt their behaviour as such changes. According to the needs of adaptability supporting in middleware, we structure a component-based, mobile agents framework in base level and meta level by using reflection. We propose concepts of meta agents and meta-service agents that are able to reflect changes made by mobile agents to the system. At the meta level of our framework, meta agents monitor execution of mobile agents and it is possible to provide dynamic adaptation of users requirements, deployment of application services and service customization with meta agents and meta-service agents.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.8
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• pp.9-16
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• 2007

Currently, the measurement of RF parameters for a base station in operation is typically limited to easily measured forward path items. In this paper, the forward monitoring ports of base stations are used to measure the reverse RF performance. The system has been implemented and effectiveness has been proven on an operating base station. The receiver sensitivity is measured using an internal CDMA modem which is used to monitor the output power based on closed loop power control when the modem is connected to the base station via a voice call. In order to improve accuracy, in addition to the modem Tx adjust(TxAdj) parameter, the detector's actual measurement is used. For accurate receiver sensitivity, the measurement should be made when there is no traffic which is not possible on an operating base station. Therefore, pilot channel chip energy to received signal power spectral density ratio$(E_c/I_o)$ compensation method is used to offset the receiver sensitivity degradation with voice traffic increase.

• Journal of Internet Computing and Services
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• v.14 no.4
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• pp.85-90
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• 2013

Currently, the electric fire prediction system uses PIC(Peripheral Interface Controller) for controller microprocessor. PIC has a slower computing speed than DSP does, so its real-time computing ability is inadequate. So with the basic characteristics waveform during arc generation as the standard reference, the comparison to this reference is used to predict and alarm electric fire from arc. While such alarm can be detected and taken care of from a remote central server, that prediction error rate is high and remote control in mobile environment is not available. In this article, the arc detection of time domain and frequency domain and wavelet-based adaptation algorithm executing the adaptation algorithm in conversion domain were applied to develop an electric fire prediction system loaded with new real-time arc detection algorithm using DSP. Also, remote control was made available through iPhone environment-based app development which enabled remote monitoring for arc's electric signal and power quality, and its utility was verified.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.9 no.6
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• pp.151-158
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• 2010

In line with the requirement of appropriate protocol support for such mission-critical wireless sensor network (WSN) applications as patient monitoring, we investigate the framework for designing medium access control (MAC) schemes. The data traffic in medical systems comes with inherent traffic heterogeneity as well as strict requirement of reliability according to the varied extents of devise-wise criticality in separate cases. This implies that the quality-of-Service (QoS) issues are very distinctly delicate requiring specialized consideration. Besides, there are features in such systems that can be exploited during the design of a MAC scheme. In a monitoring or routine surveillance application, there are degrees of regularity or predictability in traffic as coordinated from a node of central control. The coordinator thus takes on the role of marshaling the resources in a neighborhood of nodes deployed mostly for upstream traffic; in a collision-free scheme, it schedules the time slots for each superframe based on the QoS specifications. In this preliminary study, we identify the key artifacts of such a MAC scheme. We also present basic performance issues like the impact of superframe length on delay incurred, energy efficiency achieved in the network operation as obtained in a typical simulation setup based on this framework.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.376.2-376.2
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• 2014

마이크로볼로미터 적외선 센서는 인체감지, 전자부품의 품질검사, 에너지 절감, 산업시설감시 및 군사용으로 다양하게 적용되고 있다. 기존에 이러한 적외선 센서의 감지재료로 VOx 또는 비정질 Si이 가장 많이 사용되고 있으며, VOx는 감도가 높고, 세계적으로 가장 많이 사용되고 있는 물질이다. 본 연구에서는 기존의 VOx 박막 증착법을 개선하여 Zn 산화물 박막을 혼용한 적외선 감지재료를 이용한 마이크로볼로미터 제작 및 특성에 대해 보고한다. RF sputtering 방법으로 약 140 nm의 VOx/ZnO/VOx 샌드위치 박막을 증착하고, 산소분위기에서 열처리함으로써 온도저항계수(TCR)가 약 -3.0 %/K의 값을 갖는 특성을 구현하였다. 갓 증착된 V-Zn 박막에서는 XRD 스펙트럼에서는 V2O5 관련 피크가 주로 관측되었으며, 산소열처리에 의해 VO2 피크가 새롭게 관측되었다. 볼로미터 감지소자는 유효면적 $50{\times}50{\mu}m^2$ 으로 bulk micromaching 공정을 통해 제작하였다. Si 기판위에 SiNx 박막을 PECVD 장치를 이용하여 증착하였으며, 적외선 감지층으로 V-Zn 산화물을 RF sputtering 방법으로 증착하여 열처리 후 SiNx passivation 박막으로 보호하였다. 열적고립을 위해 패터닝 후 Si 기판을 KOH 용액을 이용하여 약 $20{\mu}m$ 식각하여 소자를 구현하였다. 제작된 소자의 특성을 평가한 결과 반응도는 1.57e+4 V/W, 탐지도는 $8.79e+7cmHz^{1/2}/W$를 얻을 수 있었다. 소자의 동작 특성을 평가하기 위해 진공 압력을 1e-3 torr 이하에서 thermoelectric cooler를 장착한 metal package를 제작하여 동작온도에 따른 특성을 평가하였다. 동작온도를 $10^{\circ}C{\sim}40^{\circ}C$로 하여 측정한 결과 동작온도가 증가할수록 신호전압은 감소함을 알 수 있었다.

• Journal of Internet Computing and Services
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• v.12 no.2
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• pp.123-133
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• 2011

This paper introduces security problems on the video surveillance systems where the network cameras are equipped at remote places and isolated from the updated and secure environment and proposes a framework for a proxy server that is delegated to connect to network cameras by providing a secure connections from the clients. The server in the framework is deployed within a secure network, secretes the information for connection to cameras and authenticates the clients. Additionally, it provides a secure video service incorporating multi-level privileges for both images and clients through a encryption key distribution and management facility. Through an implementation of the server and a its deployment, it was proved that In this server implement to multi network camera and we confirm compare direct access to network camera equal video quality of service and it can be protection network camera. We expect that can be secure and integral management about traditional network camera through experimental result.