• JSTS:Journal of Semiconductor Technology and Science
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• 제15권3호
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• pp.334-341
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• 2015

This research outlines the design of a HR-TDC (High Resolution Time-to-Digital Converter) for high data rate communication systems using a $0.18{\mu}m$ CMOS process. The coarse-fine architecture has been adopted to improve the resolution of the TDC. A two-stage vernier time amplifier (2S-VTA) was used to amplify the time residue, and the gain of the 2S-VTA was larger than 64. The error during time amplification was compensated using two FTDCs (Fine-TDC) with their outputs. The resolution of the HR-TDC was 0.15 ps with a 12-bit output and the power consumption was 4.32 mW with a 1.8-V supply voltage.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2002년도 Proceedings of International Symposium on Remote Sensing
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• pp.792-797
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• 2002

In the following paper two algorithms, suitable for the analysis of panchromatic data as provided by KOMPSAT-1 will be presented. One is a texture analysis which will be used to create a settlement mask based on the variations of gray values. The other is a fusion algorithm which allows the combination of high resolution panchromatic data with medium resolution multispectral data. The procedure developed for this purpose uses the spatial information present in the high resolution image to spatially enhance the low resolution image, while keeping the distortion of the multispectral information to a minimum. This makes it possible to use the fusion results for standard multispecatral classification routines. The procedures presented here can be automated to large extent, making them suitable for a standard processing routine of satellite data.

• 한국전자파학회논문지
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• 제25권4호
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• pp.467-475
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• 2014

본 논문에서는 1차원 레이더 특성(signature)인 고해상도 거리 측면도(HRRP)와 2차원 레이더 특성인 ISAR 영상을 형성하기 위하여 CS(Compressive Sensing) 기반의 레이더 신호 모델을 적용한 sparse 복원(sparse recovery) 알고리즘을 소개하고자 한다. 만약, 관측된 RCS(Radar Cross Section) 데이터 샘플에서 데이터 손실이 발생할 경우, 기존의 discrete Fourier transform(DFT) 방식으로는 올바른 고해상도의 레이더 특성들을 얻을 수 없다. 하지만, 데이터 손실이 존재하더라도 상기 sparse 복원 알고리즘을 적용하면 고해상도의 레이더 특성을 성공적으로 복원할 수 있고, 원래 광대역의 RCS 데이터를 이용한 레이더 특성과 동등하게 고해상도를 유지할 수 있다. 따라서, 본 논문에서 보여준 결과에서와 같이 원하지 않는 간섭신호나 전파 교란 신호에 의해 데이터 손실이 발생한 RCS 데이터를 수집하더라도, sparse 복원 알고리즘을 이용하면 기존 DFT 방식과 달리 고해상도의 레이더 특성을 성공적으로 복원할 수 있음을 관찰할 수 있었다.

• 한국대기환경학회지
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• 제21권2호
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• pp.179-189
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• 2005

Recently air quality modeling studies for industrial complex and large cities located in the coastal regions have been carried out. Especially, the representation of atmospheric flow fields within a model domain is very important, because an adequate air quality simulation requires an accurate portrayal of the realistic three -dimensional wind fields. Therefore this study investigated effect of using high resolution terrain height data in numerical simulation. So the experiments were designed according to the detail terrain height with 3second resolution or not. Case 30s was the experiment using the terrain height data of USGS and Case 3s was the other using the detail terrain height data of Ministry of Environment. The results of experimental were more remarkable. In Case 3s, temperature indicated similar tendency comparing to observational data predicting maximum temperature during the daytime and wind speed made weakly for difference of terrain height.

• 대한원격탐사학회지
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• 제23권5호
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• pp.483-491
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• 2007

One of the major obstacles to classify and validate Land Cover maps is the high cost of acquiring reference data. In case of inaccessible areas such as North Korea, the high resolution satellite imagery may be used for reference data. The objective of this paper is to investigate the possibility of utilizing QuickBird high resolution imagery of North Korea that can be obtained from Google Earth data via internet for reference data of land cover classification. Monthly MODIS NDVI data of nine months from the summer of 2004 were classified into L=54 cluster using ISODATA algorithm, and these L clusters were assigned to 7 classes - coniferous forest, deciduous forest, mixed forest, paddy field, dry field, water, and built-up areas - by careful use of reference data obtained through visual interpretation of the high resolution imagery. The overall accuracy and Kappa index were 85.98% and 0.82, respectively, which represents about 10% point increase of classification accuracy than our previous study based on GCP point data around North Korea. Thus we can conclude that Google Earth may be used to substitute the traditional reference data collection on the site where the accessibility is severely limited.

• 한국환경복원기술학회지
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• 제9권6호
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• pp.1-12
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• 2006

Remote sensing cannot provide a direct measurement of vegetation index (VI) but it can provide a reasonably good estimate of vegetation index, defined as the ratio of satellite bands. The monitoring of vegetation in nearby urban regions is made difficult by the low spatial resolution and temporal resolution image captures. In this study, enhancing spatial resolution method is adapted as to improve a low spatial resolution. Recent studies have successfully estimated normalized difference vegetation index (NDVI) using improved resolution method such as from the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard EOS Terra satellite. Image enhancing spatial resolution is an important tool in remote sensing, as many Earth observation satellites provide both high-resolution and low-resolution multi-spectral images. Examples of enhancement of a MODIS multi-spectral image and a MODIS NDVI image of Cheongju using a Landsat TM high-resolution multi-spectral image are presented. The results are compared with that of the IHS technique is presented for enhancing spatial resolution of multi-spectral bands using a higher resolution data set. To provide a continuous monitoring capability for NDVI, in situ measurements of NDVI from paddy field was carried out in 2004 for comparison with remotely sensed MODIS data. We compare and discuss NDVI estimates from MODIS sensors and in-situ spectroradiometer data over Ochang plain region. These results indicate that the MODIS NDVI is underestimated by approximately 50%.

• 대한원격탐사학회지
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• 제32권1호
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• pp.25-38
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• 2016

With the increasing need for high temporal resolution satellite imagery for monitoring land surfaces, this study evaluated the temporal resolution of the NDVI composites from Geostationary Ocean Color Imager (GOCI) data. The GOCI is the first geostationary satellite sensor designed to provide continuous images over a $2,500{\times}2,500km^2$ area of the northeast Asian region with relatively high spatial resolution of 500 m. We used total 2,944 hourly images of the GOCI level 1B radiance data obtained during the one-year period from April 2011 to March 2012. A daily NDVI composite was produced by maximum value compositing of eight hourly images captured during day-time. Further NDVI composites were created with different compositing periods ranging from two to five days. The cloud coverage of each composite was estimated by the cloud detection method developed in study and then compared with the Moderate Resolution Imaging Spectroradiometer (MODIS) Aqua cloud product and 16-day NDVI composite. The GOCI NDVI composites showed much higher temporal resolution with less cloud coverage than the MODIS NDVI products. The average of cloud coverage for the five-day GOCI composites during the one year was only 2.5%, which is a significant improvement compared to the 8.9%~19.3% cloud coverage in the MODIS 16-day NDVI composites.

• Journal of electromagnetic engineering and science
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• 제2권1호
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• pp.39-44
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• 2002

A high speed data link capability is one of the critical factors in determining the performance of the spaceborne SAR system with high resolution because of the strict requirement far the real-time data transmission of the massive SAR data in a limited time of mission. In this paper, based on the data lint model characterized by the spaceborne small SAR system, the high rate multi-channel data link module is designed including link storage, link processor, transmitter, and wide-angle antenna. The design results are presented with the performance analysis on the data link budget as well as the multi-mode data rate in association with the SAR imaging mode of operation from high resolution to the wide swath.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume I
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• pp.426-429
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• 2006

Flood caused by Typhoon and severe rain during summer is the most destructive natural disasters in Korea. Almost every year flood has resulted in a big lost of national infrastructure and loss of civilian lives. It usually takes time and great efforts to estimate the flood-related damages. Government also has pursued proper standard and tool for using state-of-art technologies. High resolution satellite imagery is one of the most promising sources of ground truth information since it provides detailed and current ground information such as building, road, and bare ground. Once high resolution imagery is utilized, it can greatly reduce the amount of field work and cost for flood related damage assessment. The classification of high resolution image is pre-required step to be utilized for the damage assessment. The classified image combined with additional data such as DEM and DSM can help to estimate the flooded areas per each classified land use. This paper applied object-oriented classification scheme to interpret an image not based in a single pixel but in meaningful image objects and their mutual relations. When comparing it with other classification algorithms, object-oriented classification was very effective and accurate. In this paper, IKONOS image is used, but similar level of high resolution Korean KOMPSAT series can be investigated once they are available.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2005년도 전기학술대회논문집
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• pp.757-763
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• 2005

A multi-channel seismic system has been developed and applied for bedrock mapping in near shore environment. The system is composed of an analog signal processor and an A/D converter installed on the computer, and a streamer with the group interval of 5 meters. The system is accomplished with a data acquisition program which controls the system and a data processing software. With the PC-based shallow marine seismic survey system high-resolution 2-D marine seismic profiles which have high S/N ratios can be obtained after appropriate data processing.