• Journal of Biosystems Engineering
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• v.36 no.6
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• pp.484-490
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• 2011

Defects exist underneath the fruit skin are not easily discernable by using conventional color imaging technique in the visible wavelength ranges. Development of sensitive detection methods for the defects is necessary to ensure accurate quality sorting of fruits. Hyperspectral imaging techniques, which combine the features of image and spectroscopy to acquire spatial and spectral information simultaneously, have demonstrated good potentials for identifying and detecting anomalies on biological substances. In this study, a high spatial resolution hyperspectral reflectance technique was presented as a tool for detecting bruises on apple. The two-band ratio (494 nm / 952 nm) and simple threshold methods were applied to investigate the feasibility of discriminating the bruises from sound tissue of apple. The pixel wise accuracy of the discrimination was 74%. The resultant images processed with selected wavebands and morphologic algorithm distinctively showed the early stages of bruises on apple which were not discernable by naked eyes as well as a conventional color camera. Results demonstrated good potential of the hyperspectral reflectance imaging for detection of bruises on apple.

• Proceedings of the KSRS Conference
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• 2005.10a
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• pp.637-640
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• 2005

In the development of a electronic system for a optical payload comprising mainly EOS(Electro-Optical Sub-system) and PDTS(Payload Data Transmission Sub-system), many aspects should be investigated and discussed for the easy implementation, for th e higher reliability of operation and for the effective ness in cost, size and weight as well as for the secure interface with components of a satellite bus, etc. As important aspects the interfaces between a satellite bus and a payload, and some design features of the CEU(Camera Electronics Unit) inside the payload are described in this paper. Interfaces between a satellite bus and a payload depend considerably on whether t he payload carries the PMU(Payload Management Un it), which functions as main controller of the Payload, or not. With the PMU inside the payload, EOS and PDTS control is performed through the PMU keep ing the least interfaces of control signals and primary power lines, while the EOS and PDTS control is performed directly by the satellite bus components using relatively many control signals when no PMU exists inside the payload. For the CEU design the output channel configurations of panchromatic and multi-spectral bands including the video image data inter face between EOS and PDTS are described conceptually. The timing information control which is also important and necessary to interpret the received image data is described.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.4
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• pp.598-603
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• 2003

This paper presents a sub-band feature extraction approach in which the feature extraction method in the individual frequency sub-bands is determined in terms of speech recognition accuracy. As in the multi-band paradigm, features are extracted independently in frequency sub-regions of the speech signal. Since the spectral shape is well structured in the low frequency region, the all pole model is effective for feature extraction. But, in the high frequency region, the nonparametric transform, discrete cosine transform is effective for the extraction of cepstrum. Using the sub-band specific feature extraction method, the linguistic information in the individual frequency sub-bands can be extracted effectively for automatic speech recognition. The validity of the proposed method is shown by comparing the results of speech recognition experiments for our method with those obtained using a full-band feature extraction method.

• The Journal of the Korea Contents Association
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• v.13 no.3
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• pp.1-8
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• 2013

This paper proposes a new feature extraction algorithm to improve children's speech recognition in Korean. The proposed feature extraction algorithm combines three methods. The first method is on the vocal tract length normalization to compensate acoustic features because the vocal tract length in children is shorter than in adults. The second method is to use the uniform bandwidth because children's voice is centered on high spectral regions. Finally, the proposed algorithm uses a smoothing filter for a robust speech recognizer in real environments. This paper shows the new feature extraction algorithm improves the children's speech recognition performance.

• Wind and Structures
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• v.30 no.6
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• pp.575-595
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• 2020

The characteristics of winds associated with tropical cyclones are of great significance in many engineering fields. This paper presents an investigation of wind characteristics over a coastal urban terrain based on field measurements collected from multiple cup anemometers and ultrasonic anemometers equipped at 13 height levels on a 356-m-high meteorological tower in Shenzhen during severe Typhoon Hato. Several wind quantities, including wind spectrum, gust factor, turbulence intensity and length scale as well as wind profile, are presented and discussed. Specifically, the probability distributions of fluctuating wind speeds are analyzed in connection with the normal distribution and the generalized extreme value distribution. The von Karman spectral model is found to be suitable to depict the energy distributions of three-dimensionally fluctuating winds. Gust factors, turbulence intensity and length scale are determined and discussed. Moreover, this paper presents the wind profiles measured during the typhoon, and a comparative study of the vertical distribution of wind speeds from the field measurements and existing empirical models is performed. The influences of the topography features and wind speeds on the wind profiles were investigated based on the field-measured wind records. In general, the empirical models can provide reasonable predictions for the measured wind speed profiles over a typical coastal urban area during a severe typhoon.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.2
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• pp.42.2-42.2
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• 2014

We investigate the history of formation of ~400 galaxies in four Abell clusters at 0.04

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.1
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• pp.1-6
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• 2006

High performance $Si_{0.8}Ge_{0.2}$ heterostructure metal-oxide-semiconductor field effect transistors (MOSFETs) were fabricated using well-controlled delta-doping of boron and $Si_{0.8}Ge_{0.2}$/Si heterostructure epitaxal layers grown by reduced pressure chemical vapor deposition. In this paper, we report 1/f noise characteristics of the SiGe pMOSFETs measured under various bias conditions of the gate and drain voltages changing in linear operation regions. From the noise spectral density, we found that the gate and drain voltage dependence of the noise represented same features, as usually scaled with $f^{-1}$ However, 1/f noise was found to be much lower in the device with boron delta-doped layer, by a factor of $10^{-1}_10^{-2}$ in comparison with the device fabricated without delta-doped layer. 1/f noise property of delta-doped device looks important because the device may replace bipolar transistors most commonly embedded in high-frequency oscillator circuits.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.2
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• pp.83-86
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• 2013

The optical properties of ZnO thin film have been studied using photoluminescence(PL) spectroscopy with the change of sample temperatures from 10 K to 290 K. The spectrum at 10 K showed the characteristic emission lines of ZnO which were as follows: free exciton(FX) at 3.369 eV, neutral donor-bound exciton($D^0X$) at 3.360 eV, two electron satellite(TES) at 3.332 eV, $D^0X$-1LO at 3.289 eV, and donor-acceptor pair(DAP) transiton at 3.217 eV. From the spectral evolution with temperatures, two features could be identified as temperature went higher: (1) the bound excitons changed gradually into free excitons, (2) DAP turned into free electron-acceptor transition(e,$A^0$). The PL intensity of free exciton increased with the increase of temperatures, which was accompanied by the decrease of the intensity of bound excitions and bound excition-related transitons such as TES and $D^0X$-1LO. At 80 K DAP transition disappeared, while (e,$A^0$) transition started to appear at 30 K.

• International Journal of Ocean Engineering and Technology Speciallssue:Selected Papers
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• v.4 no.1
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• pp.51-55
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• 2001

The characteristics of elastic waves emanating from crack initiation in 2024 and 5052 aluminum alloys subject to static and fatigue loading are investigated through laboratory experiments. The objective of the study is to determine difference in the properties of the signals generated from static and fatigue tests and also to examine if the sources of the waves could be identified from the temporal and spectral characteristics of the acoustic emission (AE) waveforms. The signals are recoded using non-resonant, flat, broadband transducers attached to the surface of the alloy specimens. The time dependence and power spectra of the signals recorded during the tests were examined and classified according to their special features. Three distinct types of signals were observed. The waveforms and their power spectra were found to be dependent on the material and the type of fracture associated with the signals. Analysis of the waveforms indicated that some signals could be attributed to plastic deformation associated with static tests. The potential application of the approach in health monitoring of aging aircraft structures using a network of surface mounted broadband sensors is discussed.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.1
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• pp.55.2-55.2
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• 2012

Silicate-carbon stars are characterized by oxygen-rich (O-rich) dust features despite their carbon-rich (C-rich) photospheres. While the origin of silicate-carbon stars has been a mystery ever since their discovery, the most widely accepted hypothesis is that the silicate-carbon stars have a low-luminosity companion and the O-rich material is stored in a circumbinary disk or a circumstellar disk even after the primary star becomes a carbon star. In order to study the properties of circumstellar dust envelopes of silicate-carbon stars, we perform radiative transfer model calculations using RADMC-3D with an axi-symmetric dust density distribution (a disk) as well as a spherically symmetric dust distribution. For various dust envelope models with different shapes and chemistry, we calculate the model spectral energy distributions (SEDs) and compare the model results with the observed SEDs of selected 5 silicate-carbon stars. The Circumstellar disk models are fairly well fitted with the observational data of 5 silicate-carbon stars. We find some evidences that the circumbinary disk model could be a better explanation for the origin of silicate carbon stars than the simple detached silicate dust shell model of the transition phase of the stellar chemistry.