• 한국신재생에너지학회:학술대회논문집
• /
• 2007.06a
• /
• pp.383-386
• /
• 2007

This paper describes the design and integration of the wind- fuel cell hybrid system. The hybrid system components included a wind turbine, an electrolyzer (for generation of H2), a PEMFC (Proton Exchange Membrane Fuel Cell), storage system and BOP (Balance of Plant) system. The energy input is entirely provided by a wind turbine. A DC-DC converter controls the power input to the electrolyzer, which produces hydrogen and oxygen form water. The hydrogen used the fuel for the PEMFC. The hydrogen is compressed and stored in high pressure tank by hydrogen gas booster system.

• Journal of Korea Technology Innovation Society
• /
• v.8 no.spc1
• /
• pp.499-524
• /
• 2005

The economic spillover effect from technology self-reliance of NSSS(nuclear steam supply system) by Korea Atomic Energy Research Institute was evaluated. Both production spillover effect and value added spillover effect were estimated by using Input-Output table. The production spillover effect from technology self-reliance of NSSS was estimated as 135 trillion Won during 1986-2015, while the value added spillover effect was 69 trillion Won during the same period. Besides, it was found that the technology self-reliance made great contribution to unquantifiable economic benefits such as enhancement of overall nuclear technology level, improvement of the role in international nuclear society, and improved potential to nuclear technology export.

• 한국태양에너지학회:학술대회논문집
• /
• 2008.04a
• /
• pp.190-195
• /
• 2008

This study aims to develop the thermal performance and economic analysis program of solar heating system applied to district heating systems. The program, named SOLAN-DHS, is consisted of four modules like as user's interface for system input/output, library, and utilities and a calculating engine. SOLAN-DHS simplifies user's input data through the database and can design 5 different types of solar systems. Due to the user-friendly layout, all design parameters can be changed quickly and easily for the influence on system efficiency. The reliability of SOLAN-DHS was finally verified by the experiments.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.2 no.3
• /
• pp.61-71
• /
• 1998

A performance-based seismic design method for reinforced concrete building structures being developed in Japan is outlined. Technical and scientific background of the performance-based design philosophy as well as recently developed seismic design guidelines are is presented, in which maximum displacement response to design earthquake motion is used as the limit-state design criteria. A method of estimating dynamic response displacement of the structures based on static nonlinear analysis is described. A theoretical estimation of nonlinear dynamic response considering the characteristics of energy input to the system is described in detail, which may be used as the standard method in the new performance-based code. A desing philosophy not only satisfying the criteria but also evaluating seismic capacity of the structures is also introduced.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.11 no.4
• /
• pp.1889-1910
• /
• 2017

This paper investigates a protocol so-called Adaptive Harvest Then Transmit (AHTT) for wireless powered communication networks (WPCNs) in multiple-input single-output (MISO) downlink systems, which assists in transmitting signals from a multi-antenna transmitter to a single-antenna receiver. Particularly, the power constrained relay is supplied with power by utilizing radio frequency (RF) signals from the source. In order to take advantage of multiple antennas, two different linear processing schemes, including Maximum Ratio Combining (MRC) and Selection Combination (SC) are studied. The system outage capacity and ergodic capacity are evaluated for performance analysis. Furthermore, the optimal power allocation is also considered. Our numerical and simulation results prove that the implementation of multiple antennas helps boost the energy harvesting capability. Therefore, this paper puts forward a new way to the energy efficiency (EE) enhancement, which contributes to better system performance.

• 제어로봇시스템학회:학술대회논문집
• /
• 1991.10a
• /
• pp.1091-1097
• /
• 1991

A logical and systematic procedure to derive a mathematical model for magnetically levitation(maglev) systems with a combined lift and guidance is developed by using and graph. First, bond graph is constructed for the energy-feeding system with magnetic leakage flux. And, the overall maglev system in which lift and guidance dynamics are coupled is modeled by using the concept of multi-port field in bond notations. Finally, the LQG/LTR control systems are designed for single-input single-output and for multi-input multi-output maglev systems. In this paper, it has been shown that the bond graph is an excellent method for modeling multi-energy domain systems such as maglev systems and the multivariable control system is required to improve the performance of the maglev system with a combined lift and guidance.

• ETRI Journal
• /
• v.17 no.2
• /
• pp.11-19
• /
• 1995

The plasma densities generated from a semiconductor bridge (SCB) device employing a capacitor discharge firing set have been measured by a novel diagnostic technique employing a microwave resonator probe. The spatial resolution of the probe is comparable to the separation between the two wires of the transmission lines (${\approx}$3 mm). This method is superior to Langmuir probes in this application because Langmuir probe measurements are affected by sheath effects, small bridge area, and unknown fraction of multiple ions. Measured electron densities are related to the land material and input energy. Although electron densities in the plasma generated by aluminum or tungsten-land SCB devices show a general tendency to increase steadily with power, at the higher energies, the electron densities generated from tungsten-land SCB devices are found to remain constant.

• Journal of Power Electronics
• /
• v.8 no.4
• /
• pp.345-353
• /
• 2008

In this paper, a novel loss minimization of an induction generator in wind energy generation systems is presented. The proposed algorithm is based on the flux level reduction, for which the generator d-axis current reference is estimated using support vector regression (SVR). Wind speed is employed as an input of the SVR and the samples of the generator d-axis current reference are used as output to train the SVR algorithm off-line. Data samples for wind speed and d-axis current are collected for the training process, which plots a relation of input and output. The predicted off-line function and the instantaneous wind speed are then used to determine the d-axis current reference. It is shown that the effect of loss minimization is more significant at low wind speed and the loss reduction is about to 40% at 4[m/s] wind speed. The validity of the proposed scheme has been verified by experimental results.

• The KSFM Journal of Fluid Machinery
• /
• v.13 no.5
• /
• pp.58-63
• /
• 2010

Optimal operation of turbo blowers connected in serial is analyzed by experimental measurements and numerical simulation with three-dimensional Navier-Stokes equations. The turbo blower system considered in the present study is widely used for the refuse collection system. Design optimization of the turbo blower using some design variables is also studied to enhance the performance of the blower. Throughout numerical simulation, it is found that the input energy reduction by optimal operation of the turbo blowers with the proper changes of the rotor's rotating frequency can be reduced a input energy for operating the blower system compared to the conventional on-off operation method theoretically. It is also found that the optimal design method is effective to enhance the performance of the turbo blower.

• Journal of the Korean Society of Hazard Mitigation
• /
• v.9 no.2
• /
• pp.45-51
• /
• 2009

A probabilistic approach may be adopted to predict freeze and thaw depths to account for the variability of (1) material properties, and (2) contemporary and future surface energy input parameters(e.g. air temperatures, cloud cover, snow cover) predicted with global climate models. To illustrate the probabilistic approach, an example of the predicted of thaw depths in cold regions is considered. More specifically, the Stefan equation is used together with the Monte Carlo simulation technique to make a probabilistic prediction of thaw penetration. The simulation results indicate that the variability in material properties, surface energy input parameters and temperature data can lead to significant uncertainty in predicting thaw penetration.