• Journal of applied mathematics & informatics
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• v.30 no.3_4
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• pp.531-540
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• 2012

An approximation for the number of customers at service facility in $M/G/c/K$ retrial queue is provided with the help of the approximations of ordinary $M/G/c/K$ loss system and ordinary $M/G/c$ queue. The interpolation between two ordinary systems is used for the approximation.

• Journal of applied mathematics & informatics
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• v.26 no.3_4
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• pp.511-517
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• 2008

Let G be a planar graph. It is proved that if G does not contain a k-cycle with a chord for some k ${\ni}$ {4,5,6}, then G is total-($\Delta(G)+2$)-colorable.

• Korean Journal of Agricultural Science
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• v.17 no.2
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• pp.115-129
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• 1990

This study was carried out to develop a microcomputer-based data acquisition system and software for analysis of engine vibration. Due to this development of system and software, studies on the vibration of engine was able to conduct efficiently. From the display of CRT, the outputs of test was compared and analysed on a zero-base motoring. The results obtained are summarized as follows : 1. Data acquisition system in microcomputer were designed and programmed and operated accurately. 2. The result of test was easily compared in monitoring of zero-base at color monitor. 3. This system and program developed was able to control the measuring intervals, no. of channels, and no. of data as wated. 4. The type of vibration of engine was type of bi-mode from the FFT and statistical analysis. 5. The maxima of engine vibration were 9.11 G at X-axis. 11.27 G at Y-axis, and 4.9 G at Z axis for full load of net output 6. The maxima of engine vibration unloaded were 4.28 G, 5.59 G, 2.68 G at 2200 rpm.

• Magazine of the Korean Society of Agricultural Engineers
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• v.39 no.5
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• pp.97-108
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• 1997

Natural wastewater treatment systems using the constructed wetland system were evaluated for the wastewater from the industrial complex in rural areas. For the treatment of wastewater from the industrial complex in rural area, a pilot plant of the constructed wetland system was installed at Baeksuk agri-industrial complex in ChunahnCity, Chunchungnam-Do. The experiment with this pilot plants was performed for 1996 and 1997. Results of the study were summarized as follows. For the BOD and COD, when the pollutant loading of them was about 1 3.8g/$m^2$. day (the concentration was l24.0mg/${\ell}$) arid 24.4g/$m^2$.day(the concentration was 220.Omg/${\ell}$), the removal rate of them was high, 90.2% and 93.4%, respectively. For the SS, the effluent concentration was consistently lower than the water quality standard even though the influent concentration varied significantly, which showed that SS was removed by the system effectively which consist of soil and plants. For the T-N and T-P, when the influent pollutant loading of them were moderately high, 2.8g/$m^2$.day to 7.4g/$m^2$. day(concentration 25.0mg/${\ell}$ to 49.7mg/${\ell}$) for T-N and 1.0g/$m^2$.day to 2.6g /$m^2$.day(concentration 8.6mg/${\ell}$ to 14.7mg/${\ell}$) for T-P, the removal rate of them were 86.5% and 94.0%, respectively. The removal rate by the flow distance increased rapidly in the first 4m from the inlet zone, and gradually there after. The width of system was 2m. Overall, the result showed that constructed wetland system is a feasible alternative for the treatment of wastewater from industrial complex in rural areas. Compared to existing systems, this system is quite competitive because it requires low capital cost, almost no energy and maintenance, and therefore, very cost effective.

• Journal of Korean Society for Atmospheric Environment
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• v.13 no.5
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• pp.333-343
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• 1997

The cyclone/annular denuder system/filter pack sampling system (ADS) was used to collect the acidic air pollutants in Chongju city. The data set was collected on fifty -eight different days with 24 hour sampling period from October 27, 1995 through August 25, 1996. The chemical species measured were HN $O_3$, HN $O_2$, S $O_2$ and N $H_3$ in the gas phase, and PM2.5( $d_{p}$ ＜2.5 ${\mu}{\textrm}{m}$), S $O_4$$^{2-}$, N $O_3$$^{[-10]}$ and N $H_4$$^{+}$ in the Particulate Phase. Mean concentrations measured for this study were: 0.45 $\mu\textrm{g}$/㎥ for HN $O_3$, 3.39 $\mu\textrm{g}$/㎥ for HN $O_2$, 26.4 $\mu\textrm{g}$/㎥ for S $O_2$, 3.83$\mu\textrm{g}$/㎥ for N $H_3$, 44.2 $\mu\textrm{g}$/㎥ for P $M_{2.5}$, 8.22 $\mu\textrm{g}$/㎥ for S $O_4$$^{2-}$, 3.63 $\mu\textrm{g}$/㎥ for N $O_3$$^{[-10]}$ , and 2.84 $\mu\textrm{g}$/㎥ for N $H_4$$^{- }$. HN $O_3$ and N $H_3$ were higher during the summer. However, HN $O_2$ and S $O_2$ were higher during the fall and winter. P $M_{2.5}$ , S $O_4$/ sup 2-/ and N $H_4$$^{+}$ were not showed seasonal variations, but N $O_3$$^{[-10]}$ was higher in the winter.ter.r.

• Journal of information and communication convergence engineering
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• v.16 no.2
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• pp.93-98
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• 2018

The Internet of Things (IoT) is a form of the emerging 4th industry in the 5G era. IoT is expected to develop naturally in our daily life in the 5G era in which high-speed communication will be completed. Along with the rise of IoT, concerns about security and malicious attacks are also increasing. This paper examines DoS attacks, which are one of the representative security threats of IoT and proposes a local detection and blocking system that are suitable for response to such attacks. First, systems of the LoRaWAN type, which are most actively researched in the IoT system field and DoS attacks that can occur in such systems were examined. Then, the inverse order tree algorithm using regional characteristics was designed as a cluster analysis form. Finally, a system capable of defending denial-of-service attacks in the 5G IoT system using local detection and blocking with the Euclidean distance was designed.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.4
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• pp.85-94
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• 2015

Recently, research on the smart grid that combines ICT(Information & Communication technology) to the power system has been actively progressed. If the occupancy of the EV(Electric vehicle) is increased. the V2G(Vehicle to grid) system is available which constitutes the micro-grid through battery of EV. V2G system performs load leveling and efficient energy consumption by battery operation considering load condition. But, if the battery is used only depending on the electricity rates, it doses not consider the life of the battery. The ACC(Achievable cycle) and the total transferable energy of battery varies corresponding to the selected DOD(Depth of discharge). In this paper, the optimal DOD selection method of V2G system considering battery wear cost and average driving distance of EV. Also, the total revenue prediction of various nation is presented considering the actual electricity costs per hour.

• The Journal of the Convergence on Culture Technology
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• v.7 no.4
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• pp.759-764
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• 2021

Because sensitive and private information should be exchanged between electric vehicles and a V2G service provider, reliable communication channel is essential to operate Vehicle-to-Grid (V2G) system which considers battery of electric vehicles as a factor of smart grid. The block chain is a platform for cryptocurrency transaction and fully distributed database system running by only equivalent node in the network without help of any central management or 3^rd party. In this paper, the structure and operation method of the blockchain are investigated, and the application of the blockchain for the V2G system was also explained and analyzed.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.2795-2803
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• 2011

Due to speed acceleration, higher requirements have been put forward to high speed railway communication and signaling system. The railway applications, including intra-train, train to ground and trackside networks, demand larger bandwidth, higher reliability and shorter response time from railway communication networks to ensure security operation and passenger communication. However, the current railway communication and signaling system has lagged behind the railway development, so advanced communication technologies are needed to improve the current situation. This paper presents high speed railway communication and signaling system based on 4G LTE technology, introduces its network architecture, key technology and analyzes its technical advantages compared with GSM-R system. According to analysis, LTE based high-speed railway communication network is more effective and reliable.

• The Journal of the Korea Contents Association
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• v.5 no.5
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• pp.287-295
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• 2005

This paper describes user context awareness system, which is one of the most essential technologies in various application services of ubiquitous computing. The proposed system used two-akial accelerometer, embedded in SenseWear(R)PRO2 Armband (BodyMedia). When it was worn on the right upper arm of the experiment subjects, MAD (mean of absolute difference) value of the sensor data was calculated to quantify the amount of the wear's activity. Using this data, PC-based fuzzy inference system was realized to distinguish human motion states, such as, lying, sitting, walking and running and to recognize the restricted emergency situations. In laboratory experiment, the amount of activities for tying, sitting, walking and running were 0.204 g/s, 0.373 g/s, 2.808 g/s and 16.243 g/s respectively. The recognition rates of human motion states were 96.7 %, 93.0 %, 95.2 % and 98.4 % respectively for lying, sitting, walking and running. The recognition rate of restricted emergency situation was 100%.