• Journal of the Korean Society for Precision Engineering
• /
• v.21 no.4
• /
• pp.79-87
• /
• 2004

The light pattern reflected from a machined surface contains some information like roughness and profile on the projected surface as expected in the Beckmann-Spizzichino model. In applying the theory into a real reliable measuring device, many parameters such as incident light power, wave length, spot size should be kept a constant optical value. However, the reflected light power is likely to change with the environmental noise, the variations of the light source, the reflectivity of the surface, etc. even though the incident light power is constant. In this study, a method for adjusting the incident light power to keep the reflected light power projected on a CMOS image sensor constant was proposed and a simple adjustment algorithm based on PI digital control was examined. Experiments verified that the proposed method made the surface roughness measurement better and more reliable even under variations of the height of light source.

• Journal of the Korean Society for Precision Engineering
• /
• v.21 no.6
• /
• pp.94-101
• /
• 2004

From the Beckmann's reflection model of wave incident, reflected light from a surface is known to have not only specular but also diffuse components. The specular component dominant a surface for a mirror-like surface is distributed on the almost the same area as the spot on the surface, but the diffuse component region dominant f3r a rough surface spreads scattered on the larger areas than the spot. Therefore, statistic parameters from the scattered light distribution are more meaningful in the diffuse region, while the magnitude of rather meaning in the specular region. In usual, there need two sensors to acquire two kinds of information: Photo-detector for light intensity magnitude and image sensor for light intensity distribution. But dual sensor scheme requires a beam splitter usually to feed light to each sensor, and moreover there is not a combination rule to relieve the different sensor characteristics. In this study a new method is proposed for acquisition of the dual information using only an image sensor. Specular region is established on an image area being distinguished from a diffuse component, and laser power is adjusted so that no pixel of the image sensor in the specular region is saturated. Simulation based on the light reflection theory and the experimental results are quite well matched, and thus the proposed method was proved to be very useful for mirror-like surface measurement.

• Journal of the Korean Solar Energy Society
• /
• v.27 no.3
• /
• pp.1-6
• /
• 2007

In this study, we analyze the maximum power generation of photovoltaic(PV) module depending on constituent materials and incidence angle dependence of light. To verify characteristics of constituent materials, we made photovoltaic modules with 4 kinds of solar cells and textured glass according to fabrication method. To find the degree of the maximum power generation dependence on intensity of light, Solar Simulator is applied by changing angle of module and light intensity. Through this experiment, to obtain maximum power generation from limited PV modules, it is needed to fully understand constituent materials, fabrication method and dependence of incident light characteristics.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.62 no.3
• /
• pp.371-375
• /
• 2013

A new model about output power prediction of PV module with various tilted angles and cell to cell distances has been proposed in this paper. Light intensity arrived on a solar cell could be changed by characteristics of PV module materials. Refractive indices, thickness and absorption coefficients of glass, EVA, solar cell and Backsheet are used to predict output. Also, the incident angle of light is changed 0 to 90[$^{\circ}$] and cell to cell distances are 5, 10 15[mm]. Two types of light incident on a solar cell are considered which are direct to a solar cell and reflected from Backsheet. The intensity of the incident light directly into the solar cell is reduced through glass and EVA about 17.5[%] in theoretical way. It has an error of 2.26[%] compared with experimental result. The results for compare theoretical with experimental data is validated within the error of 6.3[%]. This paper would be a research material to predict output power when the PV module is installed outdoor or a building.

• Journal of the Korean Vacuum Society
• /
• v.21 no.1
• /
• pp.62-68
• /
• 2012

The conversion efficiency of solar cells depending on incident angle of light is important for building-integrated photovoltaics (BIPV) applications. The quantum efficiency is the ratio of the number of charge carriers collected by the solar cell to the number of photons of a given energy shining on the solar cell. The analysis of angle dependence of quantum efficiencies give more information upon the variation of power output of a solar cell by the incident angle of light. The variations in power output of solar cells with increasing angle of incidence is different for the type of cell structures. In this study we present the results of the quantum efficiency measurement of single-crystalline silicon solar cells and a-Si:H thin-film solar cells with the angle of incidence of light. As a result, as the angle of incidence increases in single-crystalline silicon solar cells, quantum efficiency at all wavelength (300~1,100 nm) of light were reduced. But in case of a-Si:H thin-film solar cells, quantum efficiency was increased or maintained at the angle of incidence from 0 degree to about 40 degrees and dramatically decrease at more than 40 degrees in the range of visible light. This results of quantum efficiency with increasing incident angle were caused by haze and interference effects in thin-film structure. Thus, the structural optimization considering incident angle dependence of solar cells is expected to benefit BIPV.

• Journal of Power System Engineering
• /
• v.12 no.4
• /
• pp.46-51
• /
• 2008

Honeycomb panel has a constructive advantage because it is constructed with a honeycomb core, so it has relatively higher strength ratio to weight. Therefore honeycomb panel has been used as the light weight panels in the high-speed railway technology and high-speed ship like as cruise yachts. Also it has been used in the aircraft and aerospace industry as a structural panel because light weight structure is indispensible in that field of industry. Recently, the honeycomb panel is embossed in the viewpoints of high oil prices as the lightweight panel of the transport machine, however the sound insulation capacity of the honeycomb panel is poorer than those of uniform and another sandwich panels. In this paper a method to improving the sound absorption coefficient of a honeycomb panel Is studied by using the Helmholtz resonator. The sound absorption coefficients for some kinds of honeycomb cores are demonstrated by the normal incident absorption coefficient method.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.25 no.6
• /
• pp.647-653
• /
• 1988

A rapid thermal annealing system using tungsten halogen lamp has been designed and assembled. A control scheme where the temperature control is executed with calculated wafer temperature by considering the thermocouple delay rather than measured thermocouple temperature,is proposed. This control scheme gives more accurate control of the wafer temperature. In addition, the distribution of transmitted light power to the wafer in the system has been simulated, and lamp interval modification has been able to give more uniform light power distribution. Considering incident light spectrum, absorption, reflection, radiation of silicon, etc., temperature profile has been simulated. When the light power uniformity on the 3" wafer is below 1%, the temperature uniformity is about 2%.

• Journal of the Optical Society of Korea
• /
• v.19 no.2
• /
• pp.149-153
• /
• 2015

A digital micro-mirror device (DMD) has the potential to modulate an incident wave with high speed, and the application for holographic display has been studied by many researchers. However, the quality of reconstructed image isn't good in comparison with that from a gray-scale amplitude-only hologram since it is a binary amplitude-only spatial light modulator (SLM). In this paper, we suggest a method generating a set of binary holograms to improve the quality of the reconstructed image. Here, we are concerned with the case for which the object plane is positioned at the Fourier domain of the plane of the SLM. In this case, any point in the Fourier plane is related to all points in the hologram. So there is a chance to generate a set of binary holograms illuminated by incident wave with constant optical power. Moreover, we find an interesting fact that the quality of reconstructed image is improved when the spatial frequency bandwidth of the binary hologram is limited. Therefore, we propose an iterative segmentation algorithm generating a set of binary holograms that are designed to be illuminated by the wave with constant optical power. The feasibility of our method is experimentally confirmed with a DMD.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.27 no.1
• /
• pp.50-55
• /
• 2015

In this paper, wave energy convertors which convert incident wave energy into electric power using floating light buoy are investigated. One-tenth models of a floating light buoy, straight line and seesaw type electric power plant are manufactured and tested in wave flume. In these systems, we measure the horizontal and vertical slope, generated current and power of buoy with different wave heights and periods. This was confirmed the capability of getting electric power, then we suggest further works to get more efficiency.

• Journal of Advanced Marine Engineering and Technology
• /
• v.35 no.4
• /
• pp.500-505
• /
• 2011

In this paper, two types of micro-optic submersion detection systems are proposed and demonstrated. The structures are based on the transmission and reflection of incident light, respectively. Two collimators are separated by 10 mm and installed face to face in straight line. The incident light transmits from one side of collimator to the other through the air, but the optical loss is below 1 dB. On the other hand, when the sensors are submersed into water, most of optical power scattered into water. The systems monitor the dramatical power change to alarm the submersion. Reflection type of sensor system has a Bragg grating at the end of the sensor for back-reflection of sensing signal. This is for simple configuration of systems. The performance of two sensor systems are described in detail.