Earticle

This paper reported the measurements and modeling of noise on the 22.9kV Medium-Voltage (MV) underground power distribution cable for Broadband Power Line Communication (BPLC). The proposed measurement system was composed of inductive coupler and Digital Phosphor Oscilloscope (DPO). The empirical noise data with the measurement system was obtained from thirty-two pad mounted transformers in the test field located in Choji area of Ansan city. After conducting analysis of noise characteristics in time and frequency domain, the noise model are presented. In order to analyze the noise in frequency domain, Power Spectral Density (PSD) was computed with empirical data using Welch’s method. The model of the power line noise at each frequency carried out using Cumulative Probability Distribution (CPD) of computed noise power. It compared with common Cumulative Distribution Function (CDF) of Nakagami-m distribution, Gaussian distribution, Gamma distribution. Below 20MHz frequency range, gamma distribution was fitted with the CPD. Nakagami-m distribution provides a good fitting to the noise CPD above 20MHz frequency range.

Generally, about 67% of hydropower generation is depending on the rainy season. In other word, the process of development of water resources is too limited to a particular season. As a solution to this problem, this paper proposes an optimal control method of hydroelectric power development in multi level water dams. The main advantage of the system is stabilization of the amount of power generate in dams. Simulation results show that the proposed optimal control method indicates development rate in Chungpyung Dam is about a 40%, 25% in Chungju Dam and 37.5% in Paldang.

Air supply is a crucial parameter for many aerobic processes. Specific growth rate (μ) was determined for both the reactors (conventional UT-ALF and modified CDT-ALF) under identical operating conditions. The conventional uniform tube external loop airlift fermenter (UT-ALF) was modified keeping the volume and height same. Only the riser part of the conventional external loop airlift fermenter was replaced by a irregular geometry in the form of converging-diverging tube. The modified system is thus named converging-diverging tube airlift fermenter (CDT-ALF), which possesses a novel geometry comprised of walls with sinusoidal waves that mimic baffles in an effort to promote mixing at low Reynold’s number (Re). This geometry provides a unique hydrodynamic environment suitable also for the cultivation of mammalian cells and tissues. The results from UT-ALF and CDT-ALF were compared. At any operating condition CDTALF showed higher μmax (maximum specific growth rate) compared to UT-ALF. The highest (μmax) was observed for CDT-ALF corresponding to an initial sugar concentration of 50 kg/m3 and air flow rate of 1.0 vvm. This was 29 % higher compared to UT-ALF under identical operating conditions. So, operating cost may be minimized to a great extent if commercialized.

This paper presents performance measurements of implemented inter-vehicle communication system over various wireless WAN interfaces such as WCDMA, HSDPA and WiBro networks respectively. To show the applicability of inter-vehicle communication, a simplified V2I2V-based vehicle communication system is implemented to evaluate major performance metrics by road test. In addition, results of road test for traffic information service are investigated in view of RTT, latency and server processing time. The experimental result indicates that V2I2V-based vehicle communication system sufficiently can provide time-tolerant traffic information to moving vehicles.