• The KIPS Transactions:PartA
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• v.14A no.1 s.105
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• pp.1-14
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• 2007

MPICH-G2 is an MPI implementation to solve complex computational problems by utilizing geographically dispersed computing resources in grid environments. However, the computation nodes in MPICH-G2 are exposed to the external network due to the lack of supporting the private IP clusters, which raises the possibility of malicious security attacks. In order to address this problem, we propose MPICH-GP with a new relay scheme combining NAT(Network Address Translation) service and an user-level proxy. The proxy running on the front-end system of private IP clusters forwards the incoming connection requests to the systems inside the clusters. The outgoing connection requests out of the cluster are forwarded through the NAT service on the front-end system. Through the connection path between the pair of processes, the requested MPI jobs can be successfully executed in grid environments with various clusters including private IP clusters. By simulations, we show that the performance of MPICH-GP reaches over 80% of the performance of MPICH-G2, and over 95% in ease of using RANK management method.

• Plant Journal
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• v.12 no.4
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• pp.37-43
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• 2016

Power system which provides electricity to the accident mitigation load for nuclear power plant should be verified to maintain the proper voltage level under the various loading and source conditions. For this purpose, it was needed to collect the voltage data of safety related buses during operation of the Reactor Coolant Pump(RCP) motor and Component Cooling Water Pump(CCWP) motor, respectively, under the certain loading condition of the plant. The data (such as, voltage, current, power factor) collected from actual measurement were used to modify the existing ETAP model and then the reanalysis was conducted to simulate the testing conditions. Through these actual measurement and analysis, it ensures that the existing electrical system analysis including assumptions and methods was conducted properly. Finally, the voltage of safety related buses was not dropped below the acceptable level, and the discrepancy between two results was within the limit.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.2
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• pp.46-53
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• 2007

Extension of the mobile communication and the rapidly developing services connected with wireless multimedia(W-CDMA, DMB, Wibro, and so on) need great many base station transceiver systems, antennas, and many signal transmission line to embody these services. The min communication appliances system is exposed always in danger of transient overvoltage by direct stroke or induced lightning surge flowing in through antenna because the antenna of base station transceiver system or relay equipment is combined with expensive communication network equipments through signal transmission line. Now, gas discharge tube(GDT) or narrow band stub arrestor which is used by the surge protector for communication use is exposing limitations as for lightning surge protective means of the communication facility with high speed and wide frequency band. Therefore, for improving performance of surge arrestor, we applied ceramic filter which can reduce lightning surge invading from antenna effectively, and proved that ceramic filter is effective in residual voltage reduction through the experimental research.

• The KIPS Transactions:PartC
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• v.13C no.7 s.110
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• pp.913-922
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• 2006

It used exclusively the radio communication where is the TRS(Trunked Radio Service) at frequency where the person whom it does is specific with hitherto radio communication method differently frequency of the decimal which is allocated to the relay station it talks the at the room which the multiple user uses with commonness. The TRS system the most big feature is the region multiple group and order communication method. The TRS the composition of system is composed of the multi mind group, the each group is composed of the terminal of the users who have the objective which is similar relates in business contents. With above it follows in same multi objective and the connection of the form which is various or group communication accomplishes and quality case, a possibility a or of having many problem point in key distribution for a large scale communication there is it could be exposed to attack of the form which is various. There is a place where it accomplishes the communication which is safe at the TRS from research which it sees it investigates group key distribution method which is an essential element. The method which it sees when it reduces a communication frequency, it stands but is the user, it proposes the efficient group key distribution method it will be able to accomplish.

• International Journal of Aeronautical and Space Sciences
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• v.18 no.3
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• pp.545-554
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• 2017

Among various applications of the High Altitude Long Endurance (HALE) Unmanned Aerial Vehicle (UAV), this paper has a focus on the Global Positioning System (GPS) utilizing pseudolite and its improved performance, particularly during the multi-purpose missions. In a multi-purpose mission, the HALE UAV follows a specified flight trajectory for both navigation applications and missions. Some of the representative HALE missions are remote exploration, surveillance, reconnaissance, and communication relay. During these operations, the HALE UAV can also be an additional positioning signal source as it broadcast signals using pseudolite. The pseudolite signal can improve the availability, accuracy, and reliability of the GPS particularly in areas with poor signal reception, such as shadowed regions between tall buildings. The improvement in performance of navigation is validated through simulations of multi-purpose missions of the solar-powered HALE UAV in an urban canyon. The simulation includes UAV trajectory generation at stratosphere and uses actual geographical building data. The results indicate that the pseudolite-equipped HALE UAV has the potential to enhance the performance of the satellite navigation system in navigationally degraded regions even during multi-purpose operations.

• Journal of the Korea Safety Management & Science
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• v.19 no.4
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• pp.35-42
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• 2017

A number of plating companies have been exposed to the risk of fire due to unexpected temperature increasing of water or other reasons in a plating bath. Since the companies are not able to forecast the unexpected temperature increasing of plating bath and most of raw materials in the bath have low ignition temperature, it is easy to be exposed to the risk of fire. Thus, in previous study, we tried to monitor and notice the dangerous change of temperature of water immediately to prevent the risk of fire from plating process. However, unfortunately previous studies were not able to shut out the fundamental cause of fire since bath temperature sensor can detect air temperature when the level sensor was malfunctioned. In this paper we developed the Teflon heater which contains a built in temperature sensor and improved plating equipment system. Teflon heater is improved using Pt $100{\Omega}$ sensor which can detect until $600^{\circ}C$. When the bath temperature sensor detects over $60^{\circ}C$ or the Teflon heater sensor detects over $240^{\circ}C$ they temporarily shut down the heater to control temperature. Also relay completely shuts down main power when detects instant temperature is detected over 5% of $240^{\circ}C$ by the heater sensor to prevent teflon melting down and fire spreads. Developed plating equipment system can monitor a real time temperature in the teflon tube and bath water. Therefore we think the proposed plating equipment can eliminate the possibility of fire in plating processes fundamentally.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.3
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• pp.422-429
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• 2022

In this paper, the intermediate frequency transmission signal level between the network system-based baseband and RF unit consisting of multi-channel airborne relay devices and a lot of mission devices, which are currently undergoing technology development tasks, is kept constant at the reference signal level. Considering the other party's receiving input range, despite changes in the short-range long-range wireless communication environment, it presents a multi-link protection and MLP-A algorithm that allows signals to be transmitted stably and reliably through signal detection automatic gain control, and experiments and analysis considering short-distance and long-distance wireless environments were performed by designing, manufacturing, and implementing RF units to which MLP-A algorithms were applied, and applying distance calculation equations to the configuration of multiple air movements and verification networks. Through this, it was confirmed that a stable and reliable RF communication system can be operated.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.12 no.3
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• pp.282-289
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• 2019

Reflective and solar LED road studs are being used as a way of securing visibility for road environments. Road markers have various advantages and disadvantages in terms of versatility, efficiency, simplicity and visibility as individual products of reflective type and solar LED. However, in addition to the above, it is possible to prevent secondary accident after accident, It has a common drawback that it is difficult to have. In this paper, we propose a road stud system incorporating a wireless control function using RF - based communication with existing solar LED road studs and a system for controlling them. The proposed system is called the smart road stud system and it can control the equipment through the central control unit and the relay unit connected to the central control room by incorporating the RF communication function in the existing solar LED road stud. In addition, since it is possible to control the lighting method, color, etc. according to the road condition, it is possible to provide the driver with the state of the road to perform the function for preventing the second accident after the accident. It also adds features that minimize the ongoing power consumption of LED and RF communications. In order to verify the validity of the proposed system, prototypes were produced and it was confirmed that it is possible to act as a university for prevention of accident after accident by linking with other traffic system besides accident prevention function by securing existing visibility.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.6
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• pp.180-187
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• 2013

In this paper, we propose a LED communication based multi-hop audio data transmission network system. The main contribution and features of the proposed system are as follows. First, the contribution of this research is to develope the LED communication based multi-hop transmission network system which can transmit audio data signal with long distance via multi-hops. Second, the developed system has the following features: In transmitter, audio data is transmitted after encoding with S/PDIF format via a general LED. The relay receives digital audio signal by using photo diode and then transmits the signal to receiver after error checking and amplifying. The receiver receives the encoded audio data via photo diode and then converts to analog audio signal by using decoding and amplifying. The performance evaluation of the proposed system is conducted in the laboratory with fluorescent light source. The results of the performance evaluation confirm that the system can provide high quality audio transmission from transmiter to receiver via multi-hop relays in a long distance while we can see there are differences in the transmitted audio quality according to the used LED colors.

• Journal of IKEEE
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• v.19 no.3
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• pp.311-318
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• 2015

This dissertation proposes method for development technology of voice and SMS(Short Message Service) alarming system based on modbus protocol. The proposed technology is composed of the following 3 stages; hardware development based on microprocessor, development of input and output driver for modem, mp3 decoder, making modbus protocol stack. In the stage of hardware development based on microprocessor, we develop hardware which receives alarm from modbus master and transmit sms message, play mp3. In the stage of development of input / ouput device driver such as modem, mp3 decoder, we develop program which control each devices. In the stage of making modbus protocol stack, voice and sms alarm system is made for receiving alarm via modbus protocol. To evaluate performance of proposed technology, we issued alarm to voice and sms alarming system on purpose. As a result, response speed of detecting alarm was 10.7ms, communication distance was 1.2Km, operating temperature was from $-25^{\circ}C$ to $70^{\circ}C$, we confirmed supporting modbus protocol. And we verified that proposed voice and sms alarming system in the thesis has a performance to be used as an industrial building alarming system.