• Transactions on Electrical and Electronic Materials
• /
• v.11 no.4
• /
• pp.170-173
• /
• 2010

Nanocrystalline cadmium sulfide (CdS) thin films were prepared using chemical bath deposition in a solution bath containing $CdSO_4$, $SC(NH_2)_2$, and $NH_4OH$. The CdS thin films were investigated using X-ray diffraction (XRD), photoluminescence (PL), and Fourier transform infrared spectroscopy (FTIR). The as-deposited CdS thin film prepared at $80^{\circ}C$ for 60 min had a cubic phase with homogeneous and small grains. In the PL spectrum of the 2,900 A-thick CdS thin film, the broad red band around 1.7 eV and the broad high-energy band around 2.7 eV are attributed to the S vacancy and the band-to-band transition, respectively. As the deposition time increases to over 90 min, the PL intensity from the band-to-band transition significantly increases. The temperature dependence of the PL intensity for the CdS thin films was studied from 16 to 300 K. The $E_A$ and $E_B$ activation energies are obtained by fitting the temperature dependence of the PL intensity. The $E_A$ and $E_B$ are caused by the deep trap and shallow surface traps, respectively. From the FTIR analysis of the CdS thin films, a broad absorption band of the OH stretching vibration in the range $3,000-3,600\;cm^{-1}$ and the peak of the CN stretching vibration at $2,000\;cm^{-1}$ were found.

• Journal of Veterinary Clinics
• /
• v.20 no.3
• /
• pp.317-322
• /
• 2003

Cytogenetic and hematological analysis was performed in peripheral blood from the Korean native goat bred in the nuclear power plant (Wolsong and Uljin) and control area. The frequency of micronuclei (MN) in peripheral blood lymphocytes from goat was used as a biomarker of radiobiological effects resulting from exposure to environmental radiation. An estimated dose of radiation was calculated by best fitting linear-quadratic model based on the radiation-induced MN data over the range from 0 to 4 Gy from the goat lymphocytes with in vitro irradiation. MN rates in goats from the Wolsong and Uljin nuclear power plant, and control area were 9.60/1000, 6.83/1000 and 9.88/1000, respectively. There were no significant differences in MN frequencies and hematological values in goats between nuclear power plant and control area. High level of platelet in the goat from Uljin nuclear power plant was observed, which seemed to be related to the goat management.

• Journal of Korean Society for Atmospheric Environment
• /
• v.21 no.1
• /
• pp.1-14
• /
• 2005

In this study, a Long Path Differential Optical Absorption Spectroscopy system (K-JIST LP-DOAS) has been used to simultaneously measure atmospheric monoaromatic hydrocarbons and other trace compounds. The validity of the K-JIST LP-DOAS for measuring atmospheric monoaromatic hydrocarbons was tested during a field campaign between 12 February and 14 March 2003 at an urban site in Seoul, Korea through inter-comparative measurements against a collocated on-line Gas Chromatography (GC) system. The concentrations of benzene, toluene, p-xylene, and m-xylene were measured with the K-JIST LP-DOAS system in the UV region (239～302 nm) over a 740 m beam path. For the other trace compounds, a longer spectral range (299～362 nm) was used. In order to remove the interference of atmospheric abundant species (such as oxygen, sulfur dioxide and ozone), two oxygen optical density spectra obtained at two pathlengths, 697 and 1133m, and reference spectra of sulfur dioxide and ozone were incorporated in the fitting procedure. The mean concentrations measured by our LP-DOAS during the measurement period were 0.77 ($\pm$0.38) ppbv for benzene, 3.68 ($\pm$1.90) ppbv for toluene, 0.41 ($\pm$0.19) ppbv for p-xylene, 0.54 ($\pm$0.24) ppbv for m-xylene. The concentration data of benzene, toluene, p-xylene and m-xylene obtained by our LP-DOAS were found to be in relatively good correlations with those of the online GC system. Pearson's coefficients in the observed concentrations between LP-DOAS and on-line GC were 0.84 for benzene, 0.83 for toluene and 0.65 for m,p-xylene. This study suggests that the LP-DOAS system can be used to provide reliable information on both the mixing ratios and temporal distribution characteristics of monoaromatic hydrocarbons in the urban air.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.21 no.5
• /
• pp.555-563
• /
• 2011

The goal of image calibration is to find a relation between image and world coordinates. Conventional image calibration uses physical camera model that is able to reflect camera's optical properties between image and world coordinates. In this paper, we try to calibrate images distortion using performance criterion-based polynomial model which assumes that the relation between image and world coordinates can be identified by polynomial equation and its order and parameters are able to be estimated with image and object coordinate values and performance criterion. In order to overcome existing limitations of the conventional image calibration model, namely, over-fitting feature, the performance criterion-based polynomial model is proposed. The efficiency of proposed method can be verified with 2D images that were taken by laser scan camera.

• Journal of Korean Society of Forest Science
• /
• v.88 no.3
• /
• pp.320-326
• /
• 1999

In this study, 15 survival functions in integral and difference forms for forest plantation were derived based on assumptions for the number of surviving trees and the differential forms of the mortality rate model. Then, performance of the models was evaluated by fitting to remeasurement data of unthinned white pine(Pinus strobes) forest plantation. As a result, three equations associated with a power function of age, $t^{\beta}$, are somewhat more suitable for describing the effect of self-thinning over time. On the other hand, a general survival function for Japanese larch(Larix leptolepts) forest plantation was derived in order to exam the effect of site quality on self-thinning procedures. The results indicate that the $N_{min}$ is negatively correlated with site index and, even though the same initial stand density was assumed, the survival function curves differ in shapes associated with site index values.

• Transactions on Electrical and Electronic Materials
• /
• v.12 no.4
• /
• pp.164-168
• /
• 2011

Nanocrystalline cadmium sulphide (CdS) thin films were prepared using chemical bath deposition (CBD), and the structural, optical and photoconductive properties were investigated. The crystal structure of CdS thin film was studied by X-ray diffraction. The crystallite size, dislocation density and lattice constant of CBD CdS thin films were investigated. The dislocation density of CdS thin films initially decreases with increasing film thickness, and it is nearly constant over the thickness of 2,500 ${\AA}$. The dislocation density decreases with increasing the crystallite size. The Urbach energies of CdS thin films are obtained by fitting the optical absorption coefficient. The optical band gap of CdS thin films increases and finally saturates with increasing the lattice constant. The Urbach energy and optical band gap of the 2,900 A-thick CdS thin film prepared for 60 minutes are 0.24 eV and 2.83 eV, respectively. The activation energies of the 2,900 ${\AA}$-thick CdS thin film at low and high temperature regions were 14 meV and 31 meV, respectively. It is considered that these activation energies correspond to donor levels associated with shallow traps or surface states of CdS thin film. Also, the value of ${\gamma}$ was obtained from the light transfer characteristic of CdS thin film. The value of ${\gamma}$ for the 2,900 A-thick CdS thin film was 1 at 10 V, and it saturates with increasing the applied voltage.

• Advances in environmental research
• /
• v.5 no.3
• /
• pp.153-167
• /
• 2016

We applied multilayer perceptron (MLP) and radial basis function (RBF) neural network in upstream and downstream water quality stations of the Karaj Reservoir in Iran. For both neural networks, inputs were pH, turbidity, temperature, chlorophyll-a, biochemical oxygen demand (BOD) and nitrate, and the output was dissolved oxygen (DO). We used an MLP neural network with two hidden layers, for upstream station 15 and 33 neurons in the first and second layers respectively, and for the downstream station, 16 and 21 neurons in the first and second hidden layer were used which had minimum amount of errors. For learning process 6-fold cross validation were applied to avoid over fitting. The best results acquired from RBF model, in which the mean bias error (MBE) and root mean squared error (RMSE) were 0.063 and 0.10 for the upstream station. The MBE and RSME were 0.0126 and 0.099 for the downstream station. The coefficient of determination ($R^2$) between the observed data and the predicted data for upstream and downstream stations in the MLP was 0.801 and 0.904, respectively, and in the RBF network were 0.962 and 0.97, respectively. The MLP neural network had acceptable results; however, the results of RBF network were more accurate. A sensitivity analysis for the MLP neural network indicated that temperature was the first parameter, pH the second and nitrate was the last factor affecting the prediction of DO concentrations. The results proved the workability and accuracy of the RBF model in the prediction of the DO.

• Journal of Convergence for Information Technology
• /
• v.10 no.8
• /
• pp.35-39
• /
• 2020

DNN error is small compared to the conventional speech recognition system, DNN is difficult to parallel training, often the amount of calculations, and requires a large amount of data obtained. In this paper, we generate a phoneme unit to estimate the GMM parameters with each phoneme model parameters from the GMM to solve the problem efficiently. And it suggests ways to improve performance through clustering for a specific vocabulary to effectively apply them. To this end, using three types of word speech database was to have a DB build vocabulary model, the noise processing to extract feature with Warner filters were used in the speech recognition experiments. Results using the proposed method showed a 97.9% recognition rate in speech recognition. In this paper, additional studies are needed to improve the problems of improved over fitting.

• Journal of the Society of Naval Architects of Korea
• /
• v.44 no.4
• /
• pp.379-388
• /
• 2007

Ever increasing fuel prices and environmental concerns are forcing commercial vessel operators and designers to re-assess current vessel designs with an emphasis on their propulsion systems. The most important parameter determining propulsive efficiency is the diameter of propeller. Many investigations have been carried out to adapt a large and slow turning propeller known as one of the most robust and effective way of achieving high efficiency in ship propulsion system. However, for the same vessel a further increase of propeller diameter would require the modification of the aft end while still paying attention to the hull clearance to prevent excessive propeller excited vibrations. In order to take the advantage of this approach small workboats (e.g. tug boats, fishing vessels etc.) operate in service with a significant increase of aft draught and hence resulting "inclined keel" configuration can be observed. Although it is not unusual to see large vessels sometimes to operate with stern trim to improve their operational performance and fuel efficiency, it is rare to see a such vessel purposely built with an inclined keel feature to fit a large diameter propeller for power saving. This paper investigates the application of the inclined keel configuration to a 3600TEU container vessel with the aim of fitting an 11 % larger diameter propeller (and hence resulting 17.5 % lower rpm) to gain further power saving over the similar size basis container ship with conventional "level keel" configuration.

• Journal of the Society of Naval Architects of Korea
• /
• v.46 no.2
• /
• pp.97-104
• /
• 2009

Ever increasing fuel prices, almost doubled in the last three years, and global pressure to reduce their environmental impact have been enforcing commercial vessel operators and designers to re-assess current vessel designs with emphasis on their propulsion systems and operational practices. In this paper the "Inclined Keel Hull (IKH)" concept, which facilitates to use larger propeller diameter in combination with lower shaft speed rates and hence better transport efficiency, is explored for a modern 3600 TEU container vessel with the aim of fitting an 13 % larger diameter propeller (and hence resulting 20% lower rpm) to gain further power saving over the similar size basis container ship with conventional "level keel" configuration. It appears that successful application of the "inclined keel Hull" concept is a fine balance amongst the maximum gain in propulsive efficiency, minimum increase in hull resistance and satisfaction of other naval architectural and operational requirements. In order to make the concept economically more viable, this paper concentrates on the fore body design with the possible combination of increase of volume in its fore body to recover the expected volume loss in the aft body due to the space for larger propeller and its low wave-making resistance to minimize the efficiency loss using a well-established optimization software.