• 한국항행학회논문지
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• 제8권1호
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• pp.26-37
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• 2004

차분 위성 항법에 있어서 빈번한 동적 변화를 수반하는 항체에 대하여 편향되지 않은 위치 추정치를 생성하기 위해서는 위상 평활화 코드 필터가 널리 사용되고 있다. 위치추정, 오차해석, 고장진단, 그리고 미지정수 결정 등 보정위성항법시스템의 다양한 응용분야에 있어서 정확한 오차공분산 정보는 중요한 역할을 담당한다. 반면, 기존의 위상 평활화 코드 필터 알고리즘들은 대부분 누적위상 측정오차에 의한 시전달 오차를 무시하므로 실재에 비하여 낙관적인 오차공분산 정보를 생성할 위험성을 내포하고 있다. 위상 평활화 코드 기법의 활용에 있어서 일관성 있고 적절한 오차공분산 정보를 생성하기 위하여 본 논문에서는 Stepwise Optimal Position Projection Filter와 Stepwise Unbiased Position Projection Filter 알고리즘을 제안하였다. 제안된 필터는 기존의 필터에 비하여 누적위상의 특성에 기인하는 시전달 오차의 특성을 정확하고 상세하게 고려하여 주며 잦은 가시위성의 변화도 함께 고려할 수 있는 장점을 가진다. 몬테카를로 시뮬레이션에 의하여 수신기 Kalman 필터, 기존의 위상 평활화 코드 필터, 그리고 제안된 두 필터들의 성능을 비교 분석 하였다.

• 한국항행학회논문지
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• 제28권1호
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• pp.155-158
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• 2024

Multipath, a major error source in urban GNSS positioning (global navigation satellite system), pose a challenge due to its site-dependent nature, varying with the user's signal reception environment. In our previous study, we introduced a technique generating GNSS multipath map in urban canyon. However, due to uncertainty in initial GNSS positions, applying multipath maps required generating multiple candidate positions. In this study, we present an efficient method for applying multipath maps by projecting the multipath correction in position domain. This approach effectively applies multipath maps, addressing the challenges posed by urban user position uncertainties.

• 한국항해항만학회지
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• 제38권2호
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• pp.121-126
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• 2014

본 논문은 저가형 GPS 수신 모듈에 DGPS 서비스를 적용하기 위한 방안으로 NMEA GPGSV 데이터의 위성 배치 정보에 포함된 위성 앙각과 방위각으로 관측 행렬을 구성한 후, 거리기반 보정정보를 위치영역으로 투영하여 기 산출된 위치 오차 벡터를 수정하는 방안을 제시하였다. 저가형 수신기인 U-blox LEA-5H 모델의 출력 데이터에 제안한 알고리즘을 적용한 결과 주 활동 시간인 낮 시간에 수평 오차 RMS를 1.8m에서 1m 이내로 줄였으며, 수직 정확도는 RMS 5.8m에서 1.4m로 75% 향상시킴을 확인하였다. 본 논문에서 제안하는 방식은 하드웨어의 변경없이 소프트웨어만으로 저가형 GPS의 성능을 DGPS 수준으로 향상시키는 기법이므로, 소비자와 제조사의 부담을 경감시켜 향후 제공될 고정밀 측위 서비스 인프라의 활성화에 기여할 수 있을 것으로 기대된다.

• 한국항행학회논문지
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• 제20권5호
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• pp.433-439
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• 2016

저가형 GNSS (global navigation satellite system) 수신 모듈에 DGNSS (differential GNSS) 서비스를 적용하기 위한 방안으로 거리 영역의 보정정보를 위치 영역으로 투영한 후, stand-alone으로 산출한 위치에 적용하는 DGNSS-CP 방식이 제안된 바 있다. DGNSS-CP 를 상용 수신기 또는 휴대폰에 적용하기 위해서는 항법 방정식의 관측행렬을 이용하여 위치영역 투영 방정식을 구성하므로, 각 위성의 시선벡터를 산출하여야 한다. GNSS 항법 메시지, 배치 정보 등이 시선벡터 산출을 위하여 사용되는데, 각 방법에 따라 정확도와 연산량 등의 성능에 차이가 발생한다. 본 연구에서는 제시된 두 가지 시선벡터 산출 방식에 따라 DGNSS-CP의 성능에 어떠한 영향을 끼치는지 확인하기 위하여, Septentrio PolaRx4 Pro 수신기에서 stand-alone mode 로 저장된 데이터에 해당 알고리즘을 적용하였고, 배치 정보를 사용하는 방법이 궤도정보를 사용하는 방법에 비해 정확도 면에서는 그 성능이 RMS (root mean square) 0.1 m 가량 저하되는 반면, 연산량은 약 1/15수준으로 줄일 수 있음을 확인하였다.

• 대한음성학회지:말소리
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• 제19_20호
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• pp.58-87
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• 1990

According to Government Phonology, at 1 phonological positions save the domain's head must be licensed in order to appear in the syllable structure. A non-nuclear head is licensed by the following nucleus, and the nuclei with phonetic content are licensed through government by the nuclear head of the domain at the level of the nuclear projection. Therefore, in the theory of Government Phonology it is claimed that words always end with a nucleus. With regard to the licensing of empty nuclei, Kaye(1990a) proposes the 'Empty Category Principle' and its sub-theory of 'Projection Government'. Government Phonology claims that a nucleus which dominates a vowel that regularly undergoes elision in certain contexts is underlyingly empty. This underlying empty nucleus is not manifested phonetically when it is properly governed by an unlicensed(i, e, a nucleus filled with a full vowel). It is when proper government fails to apply, that the empty nucleus is phonetically Interpreted. The purpose of this paper is to present a principled account of the process of $[i]{\Leftrightarrow}{\emptyset}$ alternation in Korean. Following Kaye's proposal, we assume that [i] of Korean is underlyingly empty. This position is pronounced as [i] if it is unlicensed, and is not phonetically realized if is licensed. Empty nuclei ape devided into two categories: domain-internal and domain-final. Firstly, we consider the question why Korean has little word ending with [i]. As for this, ECP states that domain-final empty nuclei are not pronounced if the language licenses domain-final empty nuclei. Whether a final empty nucleus may occur in the structure is parametric variation. This property is seen from the fact that words may appear to end in consonants in this language. Since Korean abounds with words ending in a consonant, it licenses domain-final empty nuclei. Therefore, it is quite natural that Korean has little word ending with [i]. Secondly, word-internal empty nuclei of Korean respect proper government and inter-onset government. That is, an empty nucleus in word-internal position will be pronounced with the vowel [i] if either proper government or inter-onset government fail to apply. Inter-onset government refers to the government established between two onsets across an empty nucleus. Thirdly, we consider words ending with [i], which seems to be exceptional to the final licensing. Host of them are. either mono-syllabic verbs(for instance, [s'i-] 'to write') or derived adjectives ending with [p'i] (for instance, [kip'i-] 'be happy'). As for the former, the 'inaccessibility for proper government' is applied because the empty nucleus appears in the first syllable. In latter case, domain-final empty nuclei are pronounced as [i] because of government-licensing. That is, final empty nucleus is pronounced to license the preceding onset dominating negatively charmed segments which empty nucleus of Korean cannot license.

• Journal of Positioning, Navigation, and Timing
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• 제3권1호
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• pp.25-30
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• 2014

Differential Global Positioning System-Correction Projection (DGPS-CP) algorithm, which has been suggested as a method of correcting pre-calculated position error by projecting range-domain correction to positional domain, is a method to improve the accuracy performance of a low price GPS receiver to 1 to 3 m, which is equivalent to that of DGPS, just by using a software program without changing the hardware. However, when DGPS-CP algorithm is actually realized, the error is not completely eliminated in a case where a reference station does not provide correction of some satellites among the visible satellites used in user positioning. In this study, the problem of decreased performance due to the difference in visible satellites between a user and a reference station was solved by applying the Multifunctional Transport Satellites (MTSAT) based Augmentation System (MASA) correction to DGPS-CP, instead of local DGPS correction, by using the Satellite Based Augmentation System (SBAS) operated in Japan. The experimental results showed that the accuracy was improved by 25 cm in the horizontal root mean square (RMS) and by 20 cm in the vertical RMS in comparison to that of the conventional DGPS-CP.

• 한국통신학회논문지
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• 제24권12B호
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• pp.2369-2381
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• 1999

본 논문에서는 웨이브렛 변환을 이용하여 블록기반 변환 부호화 영상에서의 블록화 현상을 반복적으로 제거하는 방법을 제안하였다. 제안된 방법에서는 블록화 현상이 수직, 수평 방향의 블록 경계를 따라 수직, 수평으로만 나타나는 점에 착안하여, 블록화 현상이 있는 영상 신호를 수직, 수평 방향의 분리적인 1차원 신호의 집합으로 간주하고 Gaussian 형태 함수의 1차 도함수를 모 웨이브렛으로 하는 1차원 웨이브렛 영역에서의 평균 자승 오차를 최소화시키는 필터로써 첫 번째 스케일 웨이브렛 영역의 블록 경계 위치에서의 분산이 다른 위치에 비하여 유달리 크게 나타나도록 하는 블록화 현상에 의한 신호 성분을 제거하는 과정과 양자화에 관한 블록 집합으로 투영하는 과정을 반복적으로 수행하여 블록화 현상이 제거된 영상을 얻는다. 실험결과, 제안된 방법은 0.56 - 1.07dB의 PSNR 성능 향상뿐만 아니라 에지 몽롱화가 없이 블록화 현상이 거의 제거된 주관적 화질 개선을 보였다.

• 미술이론과 현장
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• 제7호
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• pp.165-188
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• 2009

In the development of linear perspective, Brook Taylor's theory has achieved a special position. With his method described in Linear Perspective(1715) and New Principles of Linear Perspective(1719), the subject of linear perspective became a generalized and abstract theory rather than a practical method for painters. He is known to be the first who used the term 'vanishing point'. Although a similar concept has been used form the early stage of Renaissance linear perspective, he developed a new method of British perspective technique of measure points based on the concept of 'vanishing points'. In the 15th and 16th century linear perspective, pictorial space is considered as independent space detached from the outer world. Albertian method of linear perspective is to construct a pavement on the picture in accordance with the centric point where the centric ray of the visual pyramid strikes the picture plane. Comparison to this traditional method, Taylor established the concent of a vanishing point (and a vanishing line), namely, the point (and the line) where a line (and a plane) through the eye point parallel to the considered line (and the plane) meets the picture plane. In the traditional situation like in Albertian method, the picture plane was assumed to be vertical and the center of the picture usually corresponded with the vanishing point. On the other hand, Taylor emphasized the role of vanishing points, and as a result, his method entered the domain of projective geometry rather than Euclidean geometry. For Taylor's theory was highly abstract and difficult to apply for the practitioners, there appeared many perspective treatises based on his theory in England since 1740s. Joshua Kirby's Dr. Brook Taylor's Method of Perspective Made Easy, Both in Theory and Practice(1754) was one of the most popular treatises among these posterior writings. As a well-known painter of the 18th century English society and perspective professor of the St. Martin's Lane Academy, Kirby tried to bridge the gap between the practice of the artists and the mathematical theory of Taylor. Trying to ease the common readers into Taylor's method, Kirby somehow abbreviated and even omitted several crucial parts of Taylor's ideas, especially concerning to the inverse problems of perspective projection. Taylor's theory and Kirby's handbook reveal us that the development of linear perspective in European society entered a transitional phase in the 18th century. In the European tradition, linear perspective means a representational system to indicated the three-dimensional nature of space and the image of objects on the two-dimensional surface, using the central projection method. However, Taylor and following scholars converted linear perspective as a complete mathematical and abstract theory. Such a development was also due to concern and interest of contemporary artists toward new visions of infinite space and kaleidoscopic phenomena of visual perception.