• Journal of Korean Vacuum Science & Technology
• /
• v.6 no.1
• /
• pp.51-54
• /
• 2002

Polymer EL devices of glass/ITO/PI/MEH-PPV/Al structure were fabricated using spin coating and the Ionized Cluster Beam deposition technique. PMDA-ODA type thin polyimide films which can be used as a impurity blocking layer of EL device were deposited by ICB. According to our previous results, the packing densities of polyimide films were subject to change and depend on their deposition condition. By inserting a Pl layer with various thickness and packing density, I-V characteristics and life time of the devices were investigated to determine the role of a interlayer. The blocking of impurity diffusion from ITO to luminescent layer were confirmed by XPS.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.21 no.1
• /
• pp.45-50
• /
• 1984

V-groove N+P solar cell is fabricated by thermal diffusion in silicon wafer with (100) crystal structure. To form the V-grooves in (100) silicon surface, a mixture of etylen-diamine, water, pyrocathecol is used as the etchant of anisotropic etching. Under light intensity of 100mW/$\textrm{cm}^2$, the efficiency of the V-groove solar cell is 2.5-3.5% greater than the conventional N+P solar cell and 0.4-0.6% greater than the texturized one.

• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 2009.01a
• /
• pp.638-643
• /
• 2009

A computer-generated hologram(CGH) is made for three-dimensional image reconstruction of a virtual object which is a difficult to irradiate the laser light directly. One of the adverse effect factors is quantization of wave front computed by program when a computer-generated hologram is made. Amplitude element is not considered in Kinoform, it needs processing to reduce noise or false image. So several investigation was reported that the improvement of reconstructed image of Kinoform. Means to calculate the most suitable complex amplitude distribution are iterative algorithm, simulated annealing algorithm and genetic Algorithm. Error diffusion method reconstructed to separate the object as for the noise that originated in the quantization error. So it is efficient method to obtain high quality image with not many processing.

• 한국연소학회:학술대회논문집
• /
• 2003.12a
• /
• pp.19-26
• /
• 2003

Experimental measurements of flame structure and soot characteristics were performed for ethene inverse diffusion flames (IDF). IDF has been considered as the excellent flow field to study the incipient soot because soot particle do not experience the oxidation process. In this study, LIF image clarified the reaction zone of IDF with OH signal and PAH distribution. laser light scattering technique also identified the being of soot particle. To address the degree of soot maturing, C/H ratio and morphology of soot sample were investigated. From these measurements, the effect of flow residence time and temperature on soot inception could be suggested, and more details on soot characteristic in the IDF was determined according to fuel dilution and flame condition. The fuel dilution results in a decrease of temperature and enhancement of residence time, but the critical dilution mole fraction is existed for temperature not to effect on soot growth. Also, the soot inception evolved on the specific temperature and its morphology are independent of the fuel dilution ratio of fuel.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.16 no.9
• /
• pp.1796-1804
• /
• 1992

Profiles of soot volume fraction, average diameter and particle number density have been measured using a light scattering and extinction technique in a coannular propane diffusion flame at atmosperic pressure. Temperature profiles were also obtained using a thermocouple technique. Measurements show that soot is first observed to form low in the flame in an annular region inside the main reaction zone. At higher locations this annular region widen until entire flame is observed to contain particles. Soot volume fraction and particle diameter profiles peak some 1mm on the fuel side of peak temperature and increase with height to oxidation region. Number density of the flame core drop steeply from formation region to growth region and relatively invariant to some height and decay out at flame tip.

• Nuclear Engineering and Technology
• /
• v.42 no.1
• /
• pp.73-78
• /
• 2010

The suppression of molten salt vaporization is one of the key technical issues in the electrolytic reduction process developed for recycling spent nuclear fuel from light-water reactors Since the Hertz-Langmuir relation previously applied to molten salt vaporization is valid only for vaporization into a vacuum, a diffusion model was derived to quantitatively assess the vaporization of LiCl, $Li_2O$ and Li from an electrolytic reducer operating under atmospheric pressure. Vaporization rates as a function of operation variables were calculated and shown to be in reasonable agreement with the experimental data obtained from thermogravimetry.

• Journal of The Korean Astronomical Society
• /
• v.35 no.1
• /
• pp.41-57
• /
• 2002

We have written a code called QDM_sca, which numerically solves the problem of radiative transfer in an anisotropically scattering, spherical atmosphere. First we formulate the problem as a second order differential equation of a quasi-diffusion type. We then apply a three-point finite differencing to the resulting differential equation and transform it to a tri-diagonal system of simultaneous linear equations. After boundary conditions are implemented in the tri-diagonal system, the QDM_sca radiative code fixes the field of specific intensity at every point in the atmosphere. As an application example, we used the code to calculate the brightness of atmospheric diffuse light(ADL) as a function of zenith distance, which plays a pivotal role in reducing the zodiacal light brightness from night sky observations. On the basis of this ADL calculation, frequent uses of effective extinction optical depth have been fully justified in correcting the atmospheric extinction for such extended sources as zodiacal light, integrated starlight and diffuse galactic light. The code will be available on request.

• Journal of the Korean Applied Science and Technology
• /
• v.28 no.1
• /
• pp.102-108
• /
• 2011

The study of wave propagation and scattering in biological media has become increasingly important in recent years. The propagation of light within tissues is an important problem that confronts the dosimetry of therapeutic laser delivery and the development of diagnostic spectroscopy. In the clinical application of photodynamic therapy(PDT) and in photobiology, the photon deposition within a tissue determines the spatial distribution of photochemical reactions. Scattered light is measured as a function of the distance (r) between the axis of the incident beam and the detection spot. Consequently, knowledge of the photosensitizer(Chlorophyll-a) function that characterizes a phantom is measured. To obtain the results of scattering coefficients(${\mu}s$) of a turbid material from diffusion described by experimental approach. It was measured the energy fluency of photon radiation at the position of penetration depth. From fluorescence experimental method obtained the analytical expression for the scattered light as the values of $(I/I_o)_{wavelength}$ vs the distance between the center of the incident beam and optical fiber in terms of the condition of "in situ spectroscopy(optically thick)" and real time by fluorometric measurements. The result was compromised with transport of intensities though a random distribution of scatters.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2012.02a
• /
• pp.252-252
• /
• 2012

It is widely accepted that short exciton diffusion lengths of organic semiconductors with respect to the film thickness limit the charge (hole and electron) separation before excitons recombination in organic photovoltaic (OPV) cells. Therefore the efficient absorption of incident light within the thin active organic layer is of great importance to improve the power conversion efficiency (PCE) of the cells. In this work, we fabricated 2-dimensionally (2D) nano-patterned poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOST:PSS) layers using capillary phenomenon and nano-imprinting technology at the scale of several hundred nanometers. This 2D nano-patterned PEDOT:PSS layer exerted photonic crystal effect such as redirection of light paths and variation of light intensity at specified wavelengths. It is also expected that the consequently alternated light pass lengths and intensities change the absorption properties of zinc phthalocyanine (ZnPc) thin films grown on top of the nano-patterned PEDOT:PSS layer. The influence of conductivity and thickness of the PEDOT:PSS layer on the absorption properties of ZnPc thin films were also investigated.

• Korean Journal of Materials Research
• /
• v.24 no.6
• /
• pp.305-309
• /
• 2014

When sunlight irradiates a boron-doped p-type solar cell, the formation of BsO2i decreases the power-conversion efficiency in a phenomenon named light-induced degradation (LID). In this study, we used boron-doped p-type Cz-Si solar cells to monitor this degradation process in relation to irradiation wavelength, intensity and duration of the light source, and investigated the reliability of the LID effects, as well. When halogen light irradiated a substrate, the LID rate increased more rapidly than for irradiation with xenon light. For different intensities of halogen light (e.g., 1 SUN and 0.1 SUN), a lower-limit value of LID showed a similar trend in each case; however, the rate reached at the intensity of 0.1 SUN was three times slower than that at 1 SUN. Open-circuit voltage increased with increasing duration of irradiation because the defect-formation rate of LID was slow. Therefore, we suppose that sufficient time is needed to increase LID defects. After a recovery process to restore the initial value, the lower-limit open-circuit voltage exhibited during the re-degradation process showed a trend similar to that in the first degradation process. We suggest that the proportion of the LID in boron-doped p-type Cz-Si solar cells has high correlation with the normalized defect concentrations (NDC) of BsO2i. This can be calculated using the extracted minority-carrier diffusion-length with internal quantum efficiency (IQE) analysis.