• Spatial Information Research
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• v.15 no.2
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• pp.111-121
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• 2007

The GPS positioning offer 3D position using code and carrier phase measurements, but the user can obtain the precise accuracy positioning using carrier phase in Real Time Kinematic(RTK). The main problem, which RTK have to overcome, is the necessary to have a reference station(RS) when using RTK should be generally no more than 10km on average, which is significantly different from DGPS, where distances to RS can exceed several hundred kilometers. The accuracy of today's RTK is limited by the distance dependent errors from orbit, ionosphere and troposphere as well as station dependent influences like multipath and antenna phase center variations. For these reasons, the author proposes Network based GPS Carrier Phase Differential Positioning using Multiple RS which is detached from user receiver about 30km. An important part of the proposed system is algorithm and software development, named DAUNet. The main process is corrections computation, corrections interpolation and searching for the integer ambiguity. Corrections computation of satellite by satellite and epoch by epoch at each reference station are calculated by a Functional model and Stochastic model based on a linear combination algorithm and corrections interpolation at user receiver are used by area correction parameters. As results, the users can obtain the cm-level positioning.

• Journal of the Korean Society of Propulsion Engineers
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• v.13 no.1
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• pp.10-18
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• 2009

Numerical simulation has been performed in this study to investigate the capabilities of turbulence modeling schemes on estimating the film cooling at a referenced parallel wall jet-nozzle configuration. Also a additional simulation has been performed for film cooling under 2-dimensional axis symmetry conditions at a parallel wall jet-nozzle configuration. It was concluded that the best turbulence model is the standard $k-{\epsilon}$ model with enhanced wall functions. Also a additional simulation showed the film cooling characteristics that are resonable physically.

• Horticultural Science & Technology
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• v.18 no.1
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• pp.28-32
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• 2000

This study was carried out to investigate the effects of uniconazole treatment on the growth and flowering of potted Chrysanthemum indicum L. for high quality pot plant production. Uniconazole was drenched at 0.05, 0.01, or 0.15 mg a.i./pot at 14 days after planting (DAP) of rooted cuttings. Simultaneously the short-day treatment (SDT) and pinching were adapted. The same amount of uniconazole (0.05 mg a.i./pot) was spilt drenched at once, twice, and three times, respectively, at 1 week interval. Uniconazole markedly reduced plant height, branch length, and stem diameter. Plant height was reduced linearly with increasing uniconazole concentration at 0.05, 0.01, or 0.15 mg a.i./pot up-to 41.6%, 52.5%, and 58.5%, respectively. In 0.05 mg a.i./pot, the number of branches greatly increased and plant height of 22.6 cm was adequate for pot plant. However, higher concentrations (0.10, 0.15 mg a.i.) were not suitable for production of high quality pot plant (17.0, 14.8 cm, respectively). Pinching and SDT decreased the number of days to visible bud, while uniconazole treatments delayed days to visible bud by 5-9 days compared with pinching and SDT. Number of visible buds was highest at 0.05 mg a.i./pot uniconazole treatment. However, flower diameter was decreased by uniconazole treatment, resulting in compact form. Number of stomata was increased by uniconazole treatment. The length of vascular tissues of uniconazole-treated plants ($11.2{\mu}m$) was smaller than that of non-treated plants ($15.0{\mu}m$, and the size of xylem vessel was also decreased. Uniconazole treatment at 0.05 mg a.i./pot at 14 DAP with pinching and SDT were recommended for pot plant production of C. indicum L.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.30 no.5
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• pp.445-458
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• 2012

The objective of GPS control surveying is ultimately to determine coordinate sets of control points within targeted accuracy through a series of observations and network adjustments. To this end, it is of equivalent importance for the accuracy of these coordinates to be realistically represented by using an appropriate method. The accuracy representation can be quantitively made by the variance-covariance matrices of the estimates, of which features are sensitive to the mathematical models used in the adjustment. This paper deals with impact of functional and stochastic modeling techniques into the accuracy representation of the GPS control surveying with a view of gaining background for its standardization. In order to achieve this goal, mathematical theory and procedure of the single-baseline based multi-session adjustment has been rigorously reviewed together with numerical analysis through processing real world data. Based on this study, it was possible to draw a conclusion that weighted-constrained adjustment with the empirical stochastic model was among the best scheme to more realistically describe both of the absolute and relative accuracies of the GPS surveying results.

• Annual Conference on Human and Language Technology
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• 2000.10d
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• pp.255-261
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• 2000

동사의 애매성 해소는 언어학의 여러 부문 중에서도 가장 실체가 불명확한 의미를 다루는 것이기 때문에 언어학뿐만 아니라 자연언어처리에 있어서도 가장 해결하기 어려운 문제 중에 하나이다. 애매성은 언어학에서 말하는 동음이의어와 다의어를 동시에 포괄하는 개념으로 정의된다. 단일어를 대상으로 한 이와 같은 분류는 비교적 명확한 반면 두 개의 언어 이상의 다국어를 대상으로 하는 기계번역용 사전과 같은 대역사전에 있어서는 동음이의어와 다의어의 구변은 경계가 불명확하여 의미에 기반한 대역어의 작성에 도움이 되지 않는다. 그 원인은 의미를 구성하는 세 가지 요소인 [실체], [개념], [표현]의 관점에서 [실체]와 [개념]은 어느 언어를 막론하고 보편적인 반면 [실체]와 [개념]을 최종적으로 실현하는 형대인 [표현]의 경우 각각의 언어에 따라 그 형태가 다르게 표출된다고 하는 사실 때문이다. [나무]라는 [실체]가 있다고 할 때 [나무]에 대한 [실체]와 [개념]은 언어를 초월해서 공통적이라고 할 수 있다. 한편, [개념]을 표현하는 실체인 [표현]은 언어에 따라 [namu](한국어), [ki](일본어), [tree](영어) 등과 같이 언어에 따라 자의적으로 [개념]을 표현하고 있다. [namu], [ki], [tree]가 같은 뜻을 나타낸다고 인식할 수 있는 것은 [개념]이 같기 때문이지 이들 각각의 [표현]이 의미적 연관성을 갖고 있기 때문은 아니다. 지금까지 의미를 다루는 연구에서는 이와 같은 관점이 결여됨으로 인해 의미의 다양성을 정확히 파악하는 데 한계가 있었으며 애매성 해소에 관한 연구도 부분적 시도에 그친 면이 적지 않다. 본고에서는 다국어를 대상으로 한 대역사전의 구축에 있어서 다의어와 동음이의어에 대한 종래의 분류의 문제점을 지적하고 나아가 애매성 해소의 한 방법론으로 활발히 이용되고 있는 시소러스의 분류체계의 한계를 지적한다. 나아가 이의 해결책을 한국어와 일본어의 대역사전의 구축에서 얻어진 경험을 바탕으로 제시한다.

• Proceedings of the Korean Society for Cognitive Science Conference
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• 2000.06a
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• pp.255-261
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• 2000

동사의 애매성 해소는 언어학의 여러 부문 중에서도 가장 실체가 불명확한 의미를 다루는 것이기 때문에 언어학뿐만 아니라 자연언어처리에 있어서도 가장 해결하기 어려운 문제 중에 하나이다. 애매성은 언어학에서 말하는 동음이의어와 다의어를 동시에 포괄하는 개념으로 정의된다. 단일어를 대상으로 한 이와 같은 분류는 비교적 명확한 반면 두 개의 언어 이상의 다국어를 대상으로 하는 기계번역용 사전과 같은 대역사전에 있어서는 동음이의어와 다의어의 구별은 경계가 불명확하여 의미에 기반한 대역어의 작성에 도움이 되지 않는다. 그 원인은 의미를 구성하는 세 가지 요소인 [실체], [개념], [표현]의 관점에서 [실체]와 [개념]은 어느 언어를 막론하고 보편적인 반면 [실체]와 [개념]을 최종적으로 실현하는 형태인 [표현]의 경우 각각의 언어에 따라 그 형태가 다르게 표출된다고 하는 사실 때문이다. [나무]라는 [실체]가 있다고 할 때 [나무]에 대한 [실체]와 [개념]은 언어를 초월해서 공통적이라고 할 수 있다. 한편 [개념]을 표현하는 실체인 [표현]은 언어에 따라 [namu](한국어_, [ki](일본어),[tree](영어) 등과 같이 언어에 따라 자의적으로 [개념]을 표현하고 있다. [namu], [ki], [tree]가 같은 뜻을 나타낸다고 인식할 수 있는 것은 [개념]이 같기 때문이지 이들 각각의 [표현]이 의미적 연관성을 갖고 있기 때문은 아니다. 지금까지 의미를 다루는 연구에서는 이와 같은 관점이 결여됨으로 인해 의미의 다양성을 정확히 파악하는 데 한계가 있었으며 애매성 해소에 관한 연구도 부분적 시도에 그친 면이 적지 않다. 본고에서는 다국어를 대상으로 한 대역사전의 구축에 있어서 다의어와 동음이의어에 대한 종래의 분류의 문제점을 지적하고 나아가 애매성 해소의 한 방법론으로 활발히 이용되고 있는 시소러스의 분류체계의 한계를 지적한다. 나아가 이의 해결책을 한국어와 일본어의 대역사전의 구축에서 얻어진 경험을 바탕으로 제시한다.

• Journal of Navigation and Port Research
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• v.36 no.10
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• pp.825-832
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• 2012

GPS signal delay that caused by dry gases and water vapor in troposphere is a main error source of GPS point positioning and it must be eliminated for precise point positioning. In this paper, we implemented to generate tropospheric delay grid map over the Korean Peninsula based on post-processing method by using the GPS permanent station network in order to determine the availability of tropospheric delay generation algorithm. GIPSY 5.0 was used for GPS data process and nationwide AWS observation network was used to calculate the amount of dry delay and wet delay separately. As the result of grid map's accuracy analysis, the RMSE between grid map data and GPS site data was 0.7mm in ZHD, 7.6mm in ZWD and 8.5mm in ZTD. After grid map accuracy analysis, we applied the calculated tropospheric delay grid map to single frequency relative positioning algorithm and analyzed the positioning accuracy enhancement. As the result, positioning accuracy was improved up to 36% in case of relative positioning of Suwon(SUWN) and Mokpo(MKPO), that the baseline distance is about 297km.

• Journal of Astronomy and Space Sciences
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• v.22 no.1
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• pp.1-12
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• 2005

The Korean VLBI Network (KVN) will open a new field of research in astronomy, geodesy and earth science using the newest three Elm radio telescopes. This will expand our ability to look at the Universe in the millimeter regime. Imaging capability of radio interferometry is highly dependent upon the antenna configuration, source size, declination and the shape of target. In this paper, imaging simulations are carried out with the KVN system configuration. Five test images were used which were a point source, multi-point sources, a uniform sphere with two different sizes compared to the synthesis beam of the KVN and a Very Large Array (VLA) image of Cygnus A. The declination for the full time simulation was set as +60 degrees and the observation time range was -6 to +6 hours around transit. Simulations have been done at 22GHz, one of the KVN observation frequency. All these simulations and data reductions have been run with the Astronomical Image Processing System (AIPS) software package. As the KVN array has a resolution of about 6 mas (milli arcsecond) at 220Hz, in case of model source being approximately the beam size or smaller, the ratio of peak intensity over RMS shows about 10000:1 and 5000:1. The other case in which model source is larger than the beam size, this ratio shows very low range of about 115:1 and 34:1. This is due to the lack of short baselines and the small number of antenna. We compare the coordinates of the model images with those of the cleaned images. The result shows mostly perfect correspondence except in the case of the 12mas uniform sphere. Therefore, the main astronomical targets for the KVN will be the compact sources and the KVN will have an excellent performance in the astrometry for these sources.