The purpose of this study is the realization of LED light environment closely resembling the Autumn daylight which people feel comfortable with. This research was conducted through an optical experiment and Emotional evaluation through human's eyes. Human beings are affected by the color of light, quality and light intensity. Unlike the past when human beings have worked mainly in daylight, the urbanites today spend most of the time in indoor spaces. Therefore, the artificial light is needed to strive toward a spectrum of daylight. This study is purposed to provide the pleasant light environment for human beings and build its database. This study course is expected to contribute to the new design methodology of the related fields under the development of the LED emotional lighting color.

Full-Color LED lighting system requires efficient control of the lighting color in order to easily achieve various color effects. In this paper, we present not only a portable color scanner using color sensors which can control lighting color directly from detected color but also methods to convert detected color to a complementary color, similar colors and so on. In addition, we propose a compensation method for measured sensor color to reduce measurement errors more than 50[%] in detected color. The developed color scanner is applied to control full-color LED ceiling light for emotional lighting.

In this study, a standard illuminant A type LED that has similar emission spectrum as the standard illuminant A was developed using LED chip(emission peak: 405[nm]) and four types of phosphors(blue, green orangered and red). Using the design of experiment for spectrum control, the trend of the change of spectrum shape influenced by the change of interaction among phosphors and their density could be examined. Computer simulation through the optimization of the design of experiment revealed that, among four phosphors, the most influential one on the shape of the spectrum was green phosphor. Using the obtained optimal combination ratio of the four phosphors, an alternative LED illuminant to the actual standard illuminant A was developed and the spectrums of these two were confirmed identical. Using this standard illuminant A type LED, a portable transmittance meter with the range of measurement error of [%] was developed.

In this paper, the effect of pulse current and generated heat on characteristics of the LED is measured and evaluated. For experiments, the LED driving circuit and digital logic which determines period and duty ratio of lighting are designed. At rated current, the temperature and optical characteristics of the LED with change in duty ratio and period are compared, and those of the LED with change in duty ratio and existence of cooling fan are also compared at constant average current. As a result, frequency does not affect device temperature and optical characteristic of the LED but duty ratio does. Also, the cooling fan is less effective on those of the LED at rated current.

Smart Grid has two main objectives on both supply and demand aspects which are to distribute the renewable energy sources on supply side and to develop realtime price responses on demand side. Renewable energy does not consume fossil fuels, therefore it improves the eco-friendliness and saves the cost of power system operation at the same time. Demand response increases the flexibility of the power system by mitigating the fluctuation from renewable energies, and reduces the capacity investment cost by shedding the peak load to off-peak periods. Currently Smart Grid technologies mainly focus on energy monitoring and display services but it has been proved that enabling technologies can induce the higher demand responses through many pilot projects in USA. On this context, this paper provides a price responsive algorithm for HEMS (home energy management system) on the real time pricing environment. This paper identifies the demand response as a core function of HEMS and classifies the demand into 3 categories of fixed, transferable, and realtime responsive loads which are coordinated and operated for the utility maximization or cost minimization with the optimal usage combination of three kinds of demand.

This paper proposes a boost type single-phase inverter system to compensate the voltage sag appeared on source side. The proposed system is composed of a boost converter, a PWM inverter, and a bypass diode. If the voltage sag has appeared in input voltage, the boost converter would be operated to compensate it in the proposed system. The boost converter would not be operated when the magnitude of input voltage is more than 0.9 pu. The output voltage is kept constant by a direct-quadrature frame controller in the inverter. A 300 W class boost type inverter system was simulated, and the validity of the proposed system was verified by carrying out experiments.

In this paper, the starting torque and efficiency characteristics of the induction motor (IM) for the electric vehicle (EV) are improved by changing the slot shapes of squirrel cage. The initial model of the induction motor is designed by the loading distribution method (LDM), and then the rotor with squirrel cage of NEMA class A is selected to optimize the slot shape by response surface method(RSM). The design variables of rotor slot shape are obtained by the RSM. Starting torque and efficiency were calculated by the equivalent circuit method. As a result, starting torque and efficiency of the optimized model shows good performance through whole-speed range.

Recently, photovoltaic generator system is widely extended by energy policy of the government. Add to this, for high efficiency of power generation per natural light unit area is needed to sun tracking system. And it is needed to condensed light generator for reducer of equipment expense. As method of solving this problem, this paper is developed multi-flat reflector sun tracking system for sun photocell maximum power generation. The system is consisted of multi-flat reflector and two axes machinery and sun location perceiver and AVR controller. GaAs 3J cell generated 6.75 times power more than silicon cell by times condensing light system. As a result, condensing light system of multi-flat reflector generated maximum power and showed reducing costs to photovoltaic generator.

The solid insulation system of stator windings in high voltage rotational machines is usually aging in accordance with long time operation. The partial discharge test have been known to check whether insulation deterioration exist or not, and the PD test can effectively diagnose a solid insulation condition regardless of during operation(on-line) or not(off-line). The on-line PD measurement have proven to be a successful technique in monitoring stator insulation condition nowadays. This paper describes the characteristics of comparing the on-line PD measurement data using PDMS-HG(Partial Discharge Monitoring System for Hydro-electric Generator) installed in field with the off-line diagnosis measurement data(insulation resistance, winding resistance, PI, and PD) on hydro generator(13[kV]) stator windings. These results make good use of managing rotational machines through evaluating the solid insulation condition of stator windings.

There are two main types of concentrating optical systems in use today: refractive types that use Fresnel lenses, and reflective systems that use one or more mirrors. Regardless of the chosen optical system, the result is concentrated sunlight being aimed at the sensitive face of the cell, to produce more energy from less photovoltaic material. In this paper, for the achieve trackerless CPV system, CPV module included that the spherical lens with reflect mirror makes it possible to achieve high and stable power generation performance for the high concentration photovoltaic power generation system and cope with the needs for a variety of shapes and sizes in flexible manners and that the multiple cavity assemble method greatly reduces costs. Development of these high performance multi-junction CPV module promises to accelerate growth in photovoltaic power generation.

In Korea, characterized in most cases by limited area or high earth resistivity, it is likely to design narrow distances between grounding conductors, with a view to keeping ground resistance and touch voltage below the safety margin values. A new grounding method is suggested, making use of double meshes, to lower touch voltage in a confined area, since it is difficult to lay the plugs under the ground with narrow gaps between them on a limited site. For the presentation of a new model, the suggested grounding system has been analyzed and studied in ground resistance, touch voltage and step voltage, using IEEE Std. 80 calculations and computer simulations.

This paper describes inverse E class frequency multiplier which is lower inductance and peak switching voltage than E class frequency multiplier. The frequency multiplier is designed to generate 5.8[GHz] frequency by doubling the input frequency 2.9[GHz]. The peak switching voltage of designed inverse E class frequency multiplier with 11[V] is lower 4[V] than that of E class frequency multiplier with 15[V]. The inverse E class frequency multiplier has a conversion gain 6[dB] at output power 21[dBm] and maximum 35[%] power efficiency.

This paper is tried to analysis the optical emission spectroscopy related to the position of inductive load coil and flow rates of methane and oxygen in the RF inductive plasma process. According to the position of load coil, peak of , , and CH were appeared strongly at the middle position of the coil and it decreased both direction. The electron temperature was approximately 0.9[eV] at that position. Emission intensities of , , and CH increased linearly by increasing input power. In addition, intensities of and increased by increasing the flow rate of oxygen. It might be ascribed that the oxygen species were bonded with by suppressing the combination with hydrogen atoms. Consequently, the optimal position of the inductive coil is decided to the intermediate position between 4th and 5th turns, the wanted carbon thin-film is possible to deposit by controlling flow rates of methane and oxygen.

This paper introduces and develops an efficient method for measuring power factor (PF) and its nature under nonlinear load current situations. The method is based on generating a pulse width modulated signal whose width correlates to the value of PF. This signal can then be employed as a feedback signal for controlling PF related power quantities in a system. This method has the advantages of its simple implementation, less computational complexity, and its allowable error of less than 4[%], which is justified by the computer simulation results.

In terrestrial wireless optical communication links, atmospheric effects including turbulence, absorption and scattering have significant impact on the system performance. Based on the analysis of transmission in atmospheric channel concerning 830[nm] wavelength diode laser beam, performance of free space optical (FSO) link utilizing Galilean optics as a laser beam transmitting and receving optics, PIN photodiode as a detecting device. In this paper we designed optical link equation for received optical power and we analyze the atmospheric effects on the signal to noise ratio (SNR) and bit error rate (BER) of an terrestrial FSO system. We show that the possible communication distance for BER= in proposed adverse atmospheric conditions.