• Journal of the Korean Association of Geographic Information Studies
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• v.12 no.1
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• pp.36-43
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• 2009

In this study, the impact of the covariance between the baselines on the network-based GPS positioning is analyzed. For the analysis, the multi-baseline solutions with properly modeled covariance between the baselines and the combined solutions from the single-baseline solutions are obtained, respectively. Then, the accuracies of both solutions are evaluated in terms of coordinate residuals, i.e., the differences between the positioning solutions and the published stations' coordinates. The results indicate that the positioning accuracy in static mode depends much on the geometry of GPS satellites rather than the proper modeling of covariance between the baselines. Also, slight but negligible improvement in positioning accuracy is observed in static solutions. Therefore, one may use combined solutions as an alternative to multi-baseline solutions for the network-based GPS positioning. However, multi-baseline solution with properly modeled covariance between the baselines is recommended to use especially for the applications to detect very small displacement, i.e., deformation of the building or bridge.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.4
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• pp.593-602
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• 2018

This study examined the impact of trivial baselines obtained from GNSS single-baseline processing into a network adjustment in terms of accuracy and estimated coordinates sets. To this end, depending on the inclusion of the dependent baselines, three different types of experimental GNSS networks were composed and adjusted. The results showed that the networks including the trivial baselines are generally overestimated, but differences in the derived coordinates are limited at the millimeter level. A comparison of the adjusted coordinates with those published by the national geodetic agency showed that results of the network consisting of only the independent baselines are more constant than those of the networks with trivial baselines. Finally, a trivial baseline should be excluded from the GNSS network adjustment with a consideration of the realistic accuracy presentation and data processing burden.

• Bulletin of the Korean Space Science Society
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• 2011.04a
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• pp.25.3-25.3
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• 2011

지구 또는 우주 원격탐사 및 관측에서 진일보한 임무 수행을 위해 위성 편대 비행의 필요성이 점차 부상하고 있다. 편대 비행은 단일 위성으로는 실현하기가 어렵거나 불가능한 과학적인 임무를 수행할 수 있다. 다양한 위성 편대 비행 기술에서 중요한 기술 중에 하나는 편대 위성간의 정밀기선결정 기술이며, 정밀도 검증 기술도 함께 동반되어야 한다. 이 논문에서는 Gravity Recovery and Climate Experiment(GRACE) 위성의 실제 Global Positioning System(GPS) 데이터를 사용하여 GRACE A와 B 두 위성의정밀기선결정을 수행하였다. 그리고 K/Ka-Band Ranging system(KBR) 바이어스 거리측정값으로 일괄처리 및 순차처리 방법을 통해 정밀도를 검증하였다. 제안된 순차처리 방법은 KBR 바이어스를 추정하는 대신에 기산점 차분으로 이를 제거하여 정밀도를 검증하기 때문에 검증자(KBR baised range)가 피검증자(GPS-baseline)와 독립적이고 실시간 정밀도 검증에 적용이 가능하다. 그 결과 일괄처리 검증방법과 유사한 1.5 ~ 3.0 mm의 순차처리 정밀도 검증 결과를 얻었다.

• Journal of Astronomy and Space Sciences
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• v.14 no.2
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• pp.347-354
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• 1997

We developed a GPS phase data processing S/W system which calculates baseline vectors and distances between two points located in the surface of the Earth. For this development a Double-Difference mothod and L1 carrier phase data from GPS(Global positioning System) were used. This S/W system consists of four main parts: satellite position calculation, Single-Difference equation, Double-Difference equation, and correlation. To verify our S/W, we fixed KAO($N36^{circ}.37,E127^{circ}.37,H77.61m$), one of the International GPS Services for Geodynamics, which is located at Tae-Jon, and we measured baseline vectors and relative distances with data from observations at approximate baseline distances of 2.7, 42.1, 81.1, 146.6km. Then we compared the vectors and distances with the data which we obtained from the GPSurvey S/W system, with the L1/L2 ION-Free method and broadcast ephemeris. From the comparison of the vectors and distances with the data from the GPSurvey S/W system, we found baseline vectors X, Y, Z and baseline distances matched well within the extent of 50cm and 10cm, respectively.

• Annual Conference on Human and Language Technology
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• 2002.10e
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• pp.92-97
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• 2002

의미기반 정보 검색, 자연어 질의 응답, 지식 자동 습득, 담화 처리 등 높은 수준의 자연언어처리 시스템에서 의미처리를 위한 대용량의 지식 베이스가 필요하다. 이러한 지식 베이스 중에서 가장 기본적인 것이 워드넷이다. 이러한 워드넷을 이용함으로써 여러 의미 사이의 의미 유사도를 구할 수 있고, 속성을 물려받을 수 있기 때문에 비슷한 속성을 가진 의미들을 한꺼번에 다루는 데 유용하다. 본 논문에서는 기본 어휘를 바탕으로 기존의 명사 워드넷과 단일어 사전을 이용하여 한국어 동사 워드넷을 구축하는 방법을 제시한다. 본 논문에서 1차 작업을 통하여 구축한 동사 워드넷에는 동사 1,757개에 대한 4,717개의 의미(중복을 포함하면 모두 5,235개의 의미)를 포함하고 있으며 특별히 의미가 많이 편중된 14개의 개념에 속한 571개의 의미를 53개의 세부 개념으로 재분류하여 최종적으로 모두 767개의 계층적 개념으로 구성된 동사 워드넷이 만들어 졌다.

• Horticultural Science & Technology
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• v.32 no.4
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• pp.434-439
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• 2014

This research was conducted to examine the effects of night interruption (NI) at different times on vegetative growth and flowering in Salvia splendens 'Salsa'. Plants were grown in a growth chamber under 9-h photoperiod (short-day, SD) or 9-h photoperiod plus NI with light intensity at $3-5{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ photosynthetic photon flux. The NI was applied at 18:00-22:00 HR (NI18), 22:00-02:00 HR (NI22), or 02:00-06:00 HR (NI02). The net photosynthetic rate under NI18, NI22, and NI02 increased by 0.33, 0.16, and $0.13{\mu}mol{\cdot}CO_2{\cdot}m^{-2}{\cdot}s^{-1}$, respectively, during the NI period. Dry weight, plant height, and the number of nodes under NI were not significantly different from those of the plants under SD. However, flowering was earlier by approximately 9.8 days, and the number of flowers increased to 138.7 in NI02 compared to 36.4 flowers under SD at 17 weeks after the treatment. Our results indicate that NI02 was the most effective treatment in promoting flowering. Although vegetative growth of salvia was not increased in response to the increased net photosynthesis, flowering was promoted. Under NI18, NI22, and NI02 treatments, 77.8, 88.9, and 100.0% of salvia plants flowered within 8 weeks, whereas 44.4% of the plants flowered within the same time under SD conditions.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.25 no.5
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• pp.399-405
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• 2007

Providing a precise positioning information is the primary characteristics of GPS. The relative positioning technique which utilizes the common measurements between a GPS reference station and a user is generally used to do the generation of a precise positioning. But if user is far from a GPS reference site, the properties of medium penetrated by GPS signals will be different from each other, It is difficult to eliminate the error sources such as the ionosphere and the troposphere effectively by the double differencing method. In this study the additional error correction values with the ionosphere and the troposphere to the data processing have applied. As a result, the positioning accuracy of fourteen out of seventeen testing sites were improved by appling the error correction values. We also analysed the improved rate of the positioning accuracy by the baseline.

• Journal of Astronomy and Space Sciences
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• v.21 no.4
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• pp.371-382
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• 2004

To improve the precision of relative positioning for GPS single frequency(L1) receiver, we accomplished the GPS data processing using the weighted smoothing techniques. The weighted phase smoothing technique is used to minimize the measurement error of pseudorange and position domain smoothing technique is adopted to make the complement of cycle-slip affection. we also considered some component errors like as ionospheric error, which are related with baseline length, and processed for several baselines (5, 10, 30, 40, and 150 km) to check the coverage area of this algorithm. This paper shows that weighted phase smoothing technique give more stable results after using this technique and the position domain smoothing technique can reduce the errors which are sensitive to the observational environment. Based on the results, we could find out that this algorithm is available for post-time and real-time applications and these techniques can be substitution methods which is able to get the high accuracy and precision without resolving the Integer ambiguity.

• Annual Conference on Human and Language Technology
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• 1996.10a
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• pp.21-31
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• 1996

복합명사는 한국어에서 가장 빈번하게 나타나는 색인어의 한 형태로서, 영어권 중심의 정보검색 모델로는 다루기가 어려운 언어 현상의 하나이다. 복합명사는 2개 이상의 단일어들의 조합으로 이루어져 있고, 그 형태 또한 여러 가지로 나타나기 때문에 색인과 검색의 큰 문제로 여겨져 왔다. 본 논문에서는 복합명사의 어휘적 정보를 단위명사들의 통계적 행태(statistical behavior)에 기반 하여 자동 획득하고, 이러한 어휘적 정보를 검색에 적용하는 모텔을 제시하고자 한다. 본 방법은 색인시의 복합명사 인식의 어려움과 검색시의 형태의 다양성을 극복하는 모델로서 한국어를 포함한 동양권의 언어적 특징을 고려한 모델이다.

• Annual Conference on Human and Language Technology
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• 1999.10e
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• pp.389-396
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• 1999

본 연구에서는 이미 만들어진 양국어 단일 언어 어휘 분류체계를 이용하여 양국어 어휘 분류등급 간의 개념유사도에 의한 양국어 분류체계간의 연관 관계를 구축하고자 한다. 중국어 유의어사전과 한국어 분류어휘표를 이용하여 양국어 어휘 분류체계에서의 분류등급 간의 개념유사성 및 양국어간의 어휘 유사성에 의하여 어휘분류망을 자동 구축한다. 자동 구축된 어휘분류망을 통하여 한국어 분류어휘표의 어휘 구성 및 분류체계에 대한 분석 평가를 진행할 것이며 나아가 한국어 분류어휘표에 대한 어휘 및 분류체계에 대한 보완을 시도하고자 한다. 본 연구는 한국어 자체 어휘 분류체계의 구축 방법론의 연구에도 어느 정도 도움될 것으로 기대한다.