• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2003년도 Proceedings of ACRS 2003 ISRS
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• pp.1055-1057
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• 2003

In this research, the concrete with paint film was classified using hyper-spectral remote sensing. First, spectral characteristics of concrete and concrete with some kinds of paint films were investigated with a spectrometer. Second, using reflectance and first order derivative, spectral characteristics of the normal concrete and the concrete with paint film were classified. By using hyper-spectral remote sensing, not only extraction of crack but also inspection of paint film distribution is possible.

• Journal of the Optical Society of Korea
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• 제5권1호
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• pp.9-15
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• 2001

The ocean Scanning Multi-spectral Imager (OSMI) is a payload on the KOrea Multi-Purpose SATellite (KOMPSAT) to perform worldwide ocean color monitoring f the study of biological oceanography. OSMI performs solar and dark calibrations for on-orbit instrument calibration. The purpose of the solar calibration is to monitor the degradation of imaging performance for each pixel of 6 spectral bands and to correct the degradation effect on OSMI image during the ground station date processing. The design, the operation concept, and the radiometric characteristics of the solar calibration are investigated. A linear model of image response and a solar calibration radiance model are proposed to study the instrument characteristics using the solar calibration data. The performance of spectral responsivity and spatial response uniformity. The first solar calibration data and the analysis results are important references for further study on the on-orbit stability of OSMI response during its lifetime.

• 대한원격탐사학회지
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• 제38권5_1호
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• pp.523-533
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• 2022

이 논문에서는 상호보완적인 공간 및 분광해상도를 가진 다중센서 위성영상을 이용하여 공간해상도와 분광해상도를 향상시키기 위해 영역-점 회귀 크리깅(area-to-point regression kriging, ATPRK) 기반의 2단계 spatio-spectral fusion method (2SSFM)을 제안하였다. 2SSFM은 ATPRK와 random forest 회귀 모형을 결합하여 다중센서 위성영상에서 높은 공간해상도를 갖는 분광 밴드를 예측한다. 첫 번째 단계에서는 다중센서 위성영상 사이의 공간해상도 차이를 감소시키기 위해 ATPRK 기반 공간 상세화를 수행한다. 두 번째 단계에서는 다중센서 위성영상 사이의 분광 밴드의 관계성을 정량화하기 위해 random forest를 이용한 회귀 모델링을 적용하였다. 2SSFM의 예측 성능은 적색 경계와 단파 적외선 밴드를 생성하는 사례 연구를 통해 평가하였다. 사례 연구에서 2SSFM은 실제 분광 밴드와 유사한 분광패턴을 보이면서 공간해상도가 향상된 적색 경계와 단파 적외선 밴드를 생성할 수 있었으며, 2SSFM가 고해상도 위성영상에서 제공하지 않은 분광 밴드 생성에 유용함을 확인할 수 있었다. 따라서 2SSFM을 통해 실제로 획득 불가능하지만 환경 모니터링에 효과적인 분광 밴드를 예측함으로써 다양한 분광 지수를 생성할 수 있을 것으로 기대된다.

• 말소리와 음성과학
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• 제3권4호
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• pp.109-115
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• 2011

The purposes of this study were to identify acoustic parameters of connected speech and to contribute to acoustic analysis of dysphonic voice about patient's natural speech voice as well as sustained phonation of vowels. Acoustic parameters of sentences included LTAS (long-term average spectrum) mean and spectral slope over frequence ranges such as 0-4kHz, 0-6kHz, 0-8kHz, 0-12.5kHz as well as HNR. Acoustic parameters of the vowel 'a' included jitter, RAP, shimmer, NHR, and HNR. Based on 'G' of GRBAS for the severity of dysphonia, two experienced raters judged and classified as four groups including controls, mild, moderate and severe dysphonic group. Connected speech was two sentences extracted from 'stroll' passage. Parameters of the vowel and LTAS mean of the sentences were measured by CSL. The spectral slope of the sentences and HNR of the vowel and the sentences were measured by Praat. Data were statistically analyzed by Spearman correlation and Kruskal-Wallis test using SPSS 12.0. The results of this study are as follows: First, jitter, RAP, shimmer and NHR were significantly different between the groups. Second, for several frequencies, LTAS mean and spectral slope of the sentences were significantly different between the groups. Third, the HNR of the sentences were significantly different between the groups. Forth, there was a presence of correlation between HNR and NHR of the vowel and HNR of the sentences. Accordingly, this study concluded that LTAS, spectral slope, and HNR were predictive parameters of connected speech voice for dysphonic voice.

• 말소리와 음성과학
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• 제6권3호
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• pp.91-99
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• 2014

Although it is well documented that patients with cochlear implant experience hearing difficulties when processing their first language, very little is known whether or not and to what extent cochlear implant patients recognize segments in a second language. This preliminary study examines how Korean learners of English identify English segments in a normal hearing and cochlear implant simulation conditions. Participants heard English vowels and consonants in the following three conditions: normal hearing condition, 12-channel noise vocoding with 0mm spectral shift, and 12-channel noise vocoding with 3mm spectral shift. Results confirmed that nonnative listeners could also retrieve spectral information from vocoded speech signal, as they recognized vowel features fairly accurately despite the vocoding. In contrast, the intelligibility of manner and place features of consonants was significantly decreased by vocoding. In addition, we found that spectral shift affected listeners' vowel recognition, probably because information regarding F1 is diminished by spectral shifting. Results suggest that patients with cochlear implant and normal hearing second language learners would experience different patterns of listening errors when processing their second language(s).

• 말소리와 음성과학
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• 제3권3호
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• pp.49-56
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• 2011

This study investigates how American English high back vowels are identified. American English and Korean speakers participated in a phonetic experiment for this study. This study shows their response times of the vowels and discusses how the speakers identified them. For the experiment I used a synthesized vowel continuum between American English /u/ and /$\mho$/based on American English male speakers' voice obtained by Peterson and Barney (1952). I manipulated spectral steps and vowel duration of the stimuli. The statistical results showed that American English speakers were not able to distinguish the stimuli based on spectral quality. Instead they relied on vowel duration. This suggests that the American English high back vowels have changed since Peterson and Barney recorded them in 1952. The Korean speakers also relied on vowel duration, not spectral quality since they could not distinguish them. American speakers' response times of these vowels were not affected by both spectral quality and vowel duration. Koreans' response times were affected by vowel durations only.

• 대한원격탐사학회지
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• 제28권1호
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• pp.39-54
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• 2012

본 연구의 목적은 KOMPSAT-2 위성영상에 가장 일반적으로 적용 가능한 영상융합기법을 제시하는 것이다. 가장 널리 사용되는 영상융합기법인 HPF, modified IHS, pan-sharpened, wavelet을 지역적, 계절적 특성이 서로 다른 4장의 KOMPSAT-2 위성영상에 적용하였고, 각각의 융합결과를 공간적, 분광적으로 비교분석하였다. 영상융합기법의 품질평가는 시각적 분석과 정량적 분석을 병행하여 수행하였으며, 정량적 분석에는 spatial ERGAS, spectral ERGAS, SAM, Q4가 사용되었다. 종합적인 분석결과를 고려할 때, pan-sharpened가 색상정보와 공간정보의 균형적인 보존 측면에서 다른 융합기법들에 비해, 상대적으로 우수한 결과를 나타냈다. modified-IHS의 경우, 공간정보는 잘 보존하였지만 다소 큰 색상 왜곡이 발생되었고, HPF와 wavelet은 색상 왜곡은 적었지만, 공간정보의 왜곡이 발생하였다.

• 한국지구과학회지
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• 제38권7호
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• pp.535-545
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• 2017

한반도 주변 해상사고가 증가함에 따라 원격탐사 자료를 활용한 선박탐지 연구의 중요성이 점점 더 강조되고 있다. 이 연구는 고해상도 광학영상에 의존하는 기존 선박탐지 분야에 수백 개 채널의 분광정보를 포함하는 초분광영상을 활용하여 새로운 선박탐지 알고리즘 제시하였다. 두 차례의 현장관측을 통해 측정한 선박 선체의 반사 스펙트럼과 AVIRIS (Airborne Visible/Infrared Imaging Spectrometer) 초분광센서 영상의 선박 및 해수 반사 스펙트럼 간의 분광정합 기법을 적용하였다. 총 다섯 개의 탐지 알고리즘 spectral distance similarity (SDS), spectral correlation similarity(SCS), spectral similarity value (SSV), spectral angle mapper (SAM), spectral information divergence (SID)를 사용하였다. SDS는 선박 일부가 해수로 탐지되는 오차를 나타내었고, SAM은 선박과 해수 사이에 약 1.8배의 차이를 나타내어 명확한 분류 결과를 보여주었다. 이와 더불어 본 연구에서는 각 기법의 최적 임계값을 제시하여 초분광 영상에 포함되어 있는 선박을 분류하였으며 그 결과 SAM, SID가 다른 탐지 알고리즘에 비해 우수한 선박탐지 능력을 보여주었다.

• 대한원격탐사학회지
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• 제3권1호
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• pp.1-10
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• 1987

The study was performed to recognize the most preferable spectral chennels for discriminating geological materials using the portable radiometer. The portable radiometer covers the visible and short infrared regions from approximately 0.4 to 2.5 microns which are coincided with Landsat TM, and the rock samples used for the study are pyrophylites, andesites, granite, granodiorite and silicified sedimentary rocks which are collected in Yangsan-Dongrae fault area. The analysis of the rock sample provides a preliminary basis for determining the wavelength regions showing diagnostic spectral features and for discriminating hydrothermal altered rocks from the unaltered rocks. The measurement of spectral of spectral reflectance for the rock samples was carried out in the laboratory which environment condition such as temperature, light sources, and humidity are constant. The analysis of the measured data was based on correlation between the reflectance value of the rock samples, and the follow discriptions are output of the study. 1) Pyrophyllite shows absorption at 0.83 $\mu\textrm{m}$ due to the oxidation of pyrite, and absorption at 2.22 $\mu\textrm{m}$ due to OH. 2) The altered rocks have generally higher reflectance than the unaltered rocks. 3) The ratio mesurement of pyrophyllites shows strong absorption at band 5/6 and band 6/4(in Landsat TM 5/7, 7/4). The ratio 1/5(Landsat TM 1/5) may be useful to discriminate andesite from the granite.

• 한국해양공학회지
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• 제35권4호
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• pp.257-265
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• 2021

Many studies have been performed to predict a reliable and accurate stress-range distribution and fatigue damage regarding the Gaussian wide-band stress response due to multi-peak waves and multiple dynamic loads. So far, most of the approximation models provide slightly inaccurate results in comparison with the rain-flow counting method as an exact solution. A step-by-step study was carried out to develop new approximate spectral moments that are close to the rain-flow counting moment, which can be used for the development of a fatigue damage model. Using the special parameters and bandwidth parameters, four kinds of parameter-based combinations were constructed and estimated using the R-squared values from regression analysis. Based on the results, four candidate empirical formulas were determined and compared with the rain-flow counting moment, probability density function, and root mean square (RMS) value for relative distance. The new approximate spectral moments were finally decided through comparison studies of eight response spectra. The new spectral moments presented in this study could play an important role in improving the accuracy of fatigue damage model development. The present study shows that the new approximate moment is a very important variable for the enhancement of Gaussian wide-band fatigue damage assessment.