• Aerospace Engineering and Technology
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• v.8 no.1
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• pp.132-137
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• 2009

This study has regard to classification by using multi-temporal SAR data. Multi-temporal JERS-1 SAR images are used for extract the land cover information and possibility. So far, land cover information extracted by high resolution aerial photo, satellite images, and field survey. This study developed on multi-temporal land cover status monitoring and coherence information mapping can be processing by L band SAR image. From July, 1997 to October, 1998 JERS SAR images (9 scenes) coherence values are analyzed and then extracted land cover information factors, so on. This technique which forms the basis of what is called SAR Interferometry or InSAR for short has also been employed in spaceborne systems. In such systems the separation of the antennas, called the baseline is obtained by utilizing a single antenna in a repeat pass.

• Korean Journal of Remote Sensing
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• v.29 no.4
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• pp.389-397
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• 2013

Recently high spatial resolution space-borne Synthetic Aperture Radar (SAR) systems have launched and have been operated successfully. Interferometric SAR (InSAR) processing with the space-based high resolution observations acquired by these systems can provide more detail information for various geodetic applications. Coherence is regarded as a critical parameter in the evaluating the quality of an InSAR pair. In this study, we evaluate the coherence characteristics of high-resolution data acquired by TerraSAR-X (X-band) and ALOS PALSAR (L-band) and intermediate-resolution data acquired by Envisat ASAR (C-band) over western Texas, U.S.A. Our coherence analysis reveals that the high-resolution X-band TSX (3.1 cm) data has a high coherence level (0.3-0.6), similar to that of the L-band ALOS PALSAR data (23.5 cm) in short temporal baselines. Further more, the TSX coherence values are significantly higher than those of the C-band (5.6 cm) Envisat ASAR data. The higher coherence of the TSX dataset is a surprising result, because common scattering theories suggest that the longer wavelength SAR data maintain better coherence. In vegetated areas the shorter wavelength radar pulse interacts mostly with upper sections of the vegetation and, hence, does not provide good correlation over time in InSAR pairs. Thus, we suggest that the higher coherence values of the TSX data reflect the data's high-resolution, in which stable and coherent scatters are better maintained. Although, however, the TSX data show a very good coherence with short temporal baseline (11-33 days), the coherences are significantly degraded as the temporal baselines are increased. This result confirms previous studies showing that the coherence has a strong dependency on the temporal baseline.

• Journal of Korean Society for Geospatial Information Science
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• v.25 no.2
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• pp.67-74
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• 2017

The D-InSAR is a technique for precisely measuring the subsidence of subsidence using difference of two SAR images. In order to calculate the subsidence using D-InSAR, a high coherence between master image and the slave image is essential. Since the existing D-InSAR method calculates the displacement based on the total coherence, the accuracy of the subsidence is lowered when the coherence map contains mountains or bare-land. In order to solve this problem, in this study, a point having a temporal coherence and spatial coherence of 0.7 or more was extracted to form TIN, and the subsidence was calculated based on this TIN. In addition, we compared the existing D-InSAR technique with the new D-InSAR technique considering spatial and temporal coherence. As a result, the new D-InSAR technique showed smaller standard deviation, relative variance, variation coefficient and quadrature deviation than the existing D-InSAR technique. It is also easy to grasp the trend of the subsidence.

• The Journal of Engineering Geology
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• v.32 no.2
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• pp.271-280
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• 2022

Landfast sea ice forms near coastlines in polar regions. Continuous monitoring of this sea ice is important, as it plays a key role in the marine ecosystem and affects the operation of nearby research stations. This study detected landfast sea ice around Jang Bogo research station in East Antarctica by stacking interferometric coherence images of Sentinel-1 synthetic aperture radar (SAR) data with 6-, 12- and 18-day temporal baselines. A total of 50 landfast sea ice maps were generated covering July 2017 to June 2018. The time series revealed regional differences in the timing of the maximum extent as well as growth rate of landfast sea ice. Overall, detecting landfast sea ice using interferometric SAR coherence seems promisingly feasible; however, limitations remain owing to low backscattering coefficients from new and smooth sea ice surfaces and subtle movements of sea ice in contact with the Campbell Glacier Tongue.

• Korean Journal of Remote Sensing
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• v.31 no.6
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• pp.501-512
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• 2015

Landfast sea ice (LFI) in Terra Nova Bay, East Antarctica where the Jangbogo Antarctic Research Station is located, has significant influences on marine ecosystem and the sailing of an icebreaker. Therefore, it is essential to analyze the spatio-temporal variation of the LFI in Terra Nova Bay. In this study, we chose interferometric pairs with the temporal baseline from 1 to 9 days out of a total of 62 COSMO-SkyMed synthetic aperture radar (SAR) images over Terra Nova Bay obtained from December 2010 to January 2012, and then constructed the coherence image of each pair. The LFI showed coherence values higher than 0.3 even in the interferometric SAR (InSAR) pairs of up to 9-days of temporal baseline. This was because the LFI was fixed at coastline and thus showed low temporal phase decorrelation. Based on the characteristics of the coherence on LFI, We defined the areas of LFI that show spatially homogeneous coherence values higher than 0.5. Pack ice (PI) and open water showed low coherence values due to large temporal phase decorreation caused by current and wind. Distinguishing PI from open water in the coherence images was difficult due to their similarly low coherence values. PI was identified in SAR amplitude images by investigating cracks on the ice. The extents of the LFI and PI were estimated from the coherence and SAR amplitude images and their temporal variations were analyzed. The extent of the LFI increased from March to July (maximum extent of $170.7km^2$) and decreased from October. The extent of the PI increased from February to May and decreased from May to July when the LFI increases dramatically. The extent of the LFI and air temperature showed an inverse correlation with a time lag of about 2 months, i.e., the extent of the LFI decreases after 2 months of the increase in the air temperature. Meanwhile the correlation between wind speed and the extent of the LFI was very low. This represents that the extent of LFI in Terra Nova Bay are influenced more by the air temperature than wind speed.

• Defense and Technology
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• no.2 s.156
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• pp.52-61
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• 1992

미.일 양국정부는 탈냉전의 시대를 맞이한 오늘날 양국관계가 새로운 정치.경제적 과제에 직면하고 있음을 인식함은 물론, 전후 양국이 구축해온 긴밀한 협력이 양국사회에 이익이 되었음을 인식하며, 이 기반위에 더욱 긴밀한 파트너십을 구축할 것을 약속한다. 따라서 미.일 양국정부는 이와 같은 가치에 근거한 글로벌파트너십 하에 손을 맞잡고 공정하고, 평화로우며, 번영하는 세계의 구축을 지원하는 21세기의 과제를 위해 노력할 것을다짐한다(동경선언 중에서)

• Nuclear industry
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• v.6 no.10 s.44
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• pp.77-78
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• 1986

• Journal of KIISE:Computer Systems and Theory
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• v.35 no.4
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• pp.166-171
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• 2008

We studied the variety and affinity between the successive words in the text document A number of groups were defined by the frequency of a following word in the whole text (corpus). In the previous studies, the Zipf's power law was explained by Chinese restaurant process and hub node was searched after by examining the edge number profile in scale free network. We have observed both a power law and a hub profile at the same time by studying the conditional frequency and degeneracy of a group. A symmetry between the affinity and the variety between words were found during the data analysis. And this phenomenon can be explained within a viewpoint of "exploitation and exploration." We also remark on a small symmetry breaking phenomenon in TIPSTER data.

• Journal of KIISE:Software and Applications
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• v.30 no.7_8
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• pp.681-686
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• 2003

In this paper, we describes a system that extracts important sentences from Korean newspaper articles using automatic paragraphing. First, we detect repeated words between sentences. Through observation of the repeated words, this system compute Closeness Degree between Sentences(CDS ) from the degree of morphological agreement and the change of grammatical role. And then, it automatically divides a document into meaningful paragraphs using the number of paragraph defined by the user´s need. Finally. it selects one representative sentence from each paragraph and it generates summary using representative sentences. Though our system doesn´t utilize some features such as title, sentence position, rhetorical structure, etc., it is able to extract meaningful sentences to be included in the summary.

• Korean Journal of Labor Studies
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• v.14 no.2
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• pp.267-307
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• 2008

이 논문은 일본 임금교섭의 '높은 수준의 조율'과 '상당한 기업규모별 임금격차의 존재'라는 일견 서로 모순되는 두 현상을 종합적으로 이해하고자 하였다. 이를 위해 우선 일본에서의 기업규모별 임금격차의 상황을 보았다. 여기서 상당한 정도의 임금격차가 있다는 것을 재확인했다. 그렇지만 일본의 임금격차의 양상은 보다 복합적이어서 소정내 임금을 기준으로 할 때 초임에서는 기업규모별 임금격차가 거의 없었다. 또한 1970년대 이후 1990년대까지 기업규모별 임금격차가 거의 확대되지 않았으며, 한국과 비교할 때 기업규모별 임금격차는 작았다. 이렇게 된 한 가지 이유는 임금교섭인 춘투가 긴밀하게 조율됨으로써 초임이 통일되었고 기업간 평균임금의 격차를 일정 범위 내로 제한할 수 있었기 때문이다. 그리고 기업별 교섭이 긴밀하게 조율될 수 있었던 데에는 일단 '통일투쟁'을 주도한 노조의 전략이 중요한 요인이었다. 통일투쟁의 선두에 선 대기업 노조들은 기업 내에서의 임금극대화보다는 사회적 임금결정 기준을 형성하는 데에 노력했다. 이와 함께 노조에 맞서 강한 단결을 유지하고 긴밀한 협의체제를 만들어간 사용자의 대응 역시 결정적 요인이었다. 그럼에도 상당 폭으로 존재하는 임금격차 역시 임금교섭의 양상과 연관되어 있다. 기업별 교섭이 긴밀히 조율되긴 하나 조율에 한계가 있어서 임금격차를 어느 한도 이상 줄이지 못하는 것이다. 조율의 한계로는 첫째 노조 연대임금 정책의 부재, 둘째 기업별 교섭으로 인한 전국적 조율의 한계, 셋째 연공적 임금체계 하에서 기업횡단적 임금결정 기준이 부재한 것 등을 들 수 있다.