• The Bulletin of The Korean Astronomical Society
• /
• v.46 no.1
• /
• pp.39.2-40
• /
• 2021

본 연구는 《숭전역서》 혹은 《서양신법역서》 이후, 하국종(何國宗, ? -1767)과 매각성(梅殼成, 1681-1764) 등에 의해 기술된 《역상고성》 상하편에 실린 <일전역리>, <일전역법>, <일전표>를 바탕으로 태양의 운동을 자세히 살펴보았다. 《숭전역서》 <일전역리>에서는 티코브라헤의 혼합모형을 기반에 두었지만 태양의 운동은 톨레미(Ptolemy)의 이심모델(Eccentric model)과 차이가 없다. 그러나 <일전표>에 수록된 가감차의 값은 이퀀트모델(Equant model)을 기초로 한 것이었다. 《신법산서》 <일전표>에는 이 모델에 의한 계산법을 소개하고 있으나 계산의 오류를 범하였다. 태양 실측과의 어긋남, 태양의 운동을 기술하는 여러 상수들이 다시 얻어짐에 따라 《역상고성》 상하편의 <일전역리>에서는 코페르니쿠스 모델을 기초로 한 본륜-균륜 모델을 채택하고 있다. 이 모델을 기초로 한 가감차 계산 과정에 조금의 수학적 오류가 있지만 계산 결과에는 영향을 미치지 않았다. 그리고 <일전표>에 제시된 가감차값은 바로 이 모델을 기반으로 한 값들이다. <일전역법>에 제시된 동지 이후 태양의 실제 경도를 구하는 방법이 매우 구체적이다. 이 방법은 이후 《역상고성후편》의 <일전역법>도 그대로 따르고 있는데 다만 《역상고성후편》의 <일전역리>는 케플러의 타원모델을 채택하고 있다. 태양의 황경을 구하는 현재의 방법과 비교해보면 《역상고성》 <일전역법>에서는 그 기준이 동지이고 현재의 방법은 춘분점이라는 것만 다를 뿐이고, 방법은 동일하다. 다만 필요한 상수 값들이 시간에 따라 아주 느리게 변하기에 이 값들의 보정이 필요할 뿐이다. 이 방법은 조선에서 집필된 《세초류휘》, 《시헌기요》, 《추보속해》, 《추보첩례》에도 사용한 모델과 상수들은 다르지만 동일한 방법을 요약하고 있다.

• Journal of Korea Water Resources Association
• /
• v.40 no.9
• /
• pp.743-754
• /
• 2007

This study theoretically compared three possible methods for the ground-truth, that is three ground-truth designs of radar rainfall using the rain gauge rainfall. Theoretical results derived are first applied to the rainfall field generated by the Waymire-Gupta-Rodriguez Iturbe(WGR) model, and then to the Mt. Gwanak radar data using the rain gauge data from MOCT within the radar range of observation. Overall application results were found to be similar to those from theoretical studies, also those from the application to the WGR rainfall field. In conclusion, the ground-truth design using only positive(+) rainfalls from both radar and rain gauges causes serious design bias to be inappropriate as a ground-truth design.

• Journal of the Korean Vacuum Society
• /
• v.5 no.4
• /
• pp.292-300
• /
• 1996

The scattering of incident ions and target atoms in the amorphous solid matters are calculated by Monte Carlo simulation method. The experimentally derived universal scattering cross-section of Kalbitzer and Oetzmann is used to describe nuclear scattering. For electronic energy loss, the Lindhard-Scharff and Bethe formula are used. Comparing the ion scattering formulas and ranges with the known results of experiment and other programs, we find our results are good agreement with others.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.32 no.5
• /
• pp.527-537
• /
• 2014

In 2013, NGII(National Geographic Information Institute) has developed and provided the KNGeoid13(Korean National Geoid Model 2013) to support the fundamental computation of GNSS-derived orthometric height. In this study, the adjusted ellipsoidal height, the sum of geoidal height and height by the leveling, is applied to calculate the GNSS-derived orthometric height without the local bias, based on GNSS static surveying and KNGeoid13. The mean of errors in GNSS-derived orthometric heights could be verified with the leveling data, which was actually less than 0.5 cm with using the adjusted ellipsoidal heights, but 3 cm by calculating differences between ellipsoidal heights and geoidal heights. By analyze the accuracy of GNSS-derived orthometric height depending on the duration of observation, we could realized 95% of data shows less than 4 cm accuracy, when the GNSS survey conducting for 4 hours spread over two days, but while the case of GNSS survey conducting for 4 hours and 2 hours respectively, resulted in 95% of data less than 5cm level of accuracy. Also, if the ambiguity is fixed, less than 10cm of accuracy could be obtained at 95% of data for only 30 minutes GNSS survey over a day. Following the study, we expected that the height determination by GNSS and geoid models can be used in the public benchmark surveying.

• Journal of Korean Society for Geospatial Information Science
• /
• v.4 no.2 s.8
• /
• pp.79-90
• /
• 1996

It is well known that point positioning using a C/A-code receiver is severely biased by errors in pseudorange. This paper shows the procedures of quantitive analysis for several error elements and that some methods to monitor SA(selective availability) of witch process is not opened are proposed. It is possible to verify the effects of SA in the Doppler shift and receiver clock drift variation. Easy methods to reduce SA effects are to fit second order polynomials for the one and a linear function for the other. With periodic autocorrelation functions. SA effects are analyzed and first order Gauss-Markov process parameters are decided.

• Journal of agricultural medicine and community health
• /
• v.45 no.3
• /
• pp.130-140
• /
• 2020

목적: 본 연구는 65세 이상 농업인과 비농업인의 노화에 따른 취약성을 파악하고 차이를 비교 분석하고자 하였다. 방법: 본 연구는 단면 연구로서 강원도에 거주하는 고령의 농업인 29명과 비농업인 25명이 연구에 참여하였다. 노화에 대한 취약성 평가를 위해 노쇠, 신체 구성, 인지·신체 기능, 심리 상태를 검사하였다. 결과: 집단 간 유의한 차이가 있었던 배우자 유무를 보정하여 편 상관 분석한 결과, 농업인에서만 나이와 취약성 요소 간 유의한 상관관계가 있었으며, 편 상관 계수를 비교하였을 때 body mass index(BMI, r = -0.625 vs 0.026, P < 0.01), 우울도(r = 0.521 vs -0.046, P < 0.05)에서 유의한 차이가 있었다. 결론: 고령의 농업인과 비농업인의 노화에 대한 취약성을 비교하였을 때 나이와 취약성 요소 간 유의한 상관관계는 농업인에서만 나타나 비농업인과는 차별적인 패턴을 보였다. 이러한 결과는 농촌의 고령 농업인에 대하여 건강한 노화를 위한 예방 및 관리 전략이 필요함을 시사한다.

• 한국HCI학회:학술대회논문집
• /
• 2008.02c
• /
• pp.172-177
• /
• 2008

Biometrics is essential for person identification because of its uniqueness from each individuals. Face recognition technology has advantage over other biometrics because of its convenience and non-intrusive characteristics. In this paper, we will present a overview of face recognition technology including face detection, feature extraction, and face recognition system. For face detection, we will describe template based method and face component based approach. PCA and LDA approach will be discussed for feature extraction, and nearest neighbor classifiers -will be covered for matching. Large database and the standardized performance evaluation methodology is essential in order to support state-of-the-art face recognition system. Also, 3D based face recognition technology is the key solution for the pose, lighting and expression variations in many applications.

• Survey Research
• /
• v.9 no.2
• /
• pp.1-27
• /
• 2008

Problems of incomplete data are pervasive in statistical analysis. In particular, incomplete data have been an important challenge in repeated measures studies. The objective of this study is to give a brief introduction to missing data mechanisms and conventional/recent missing data methods and to assess the performance of various missing data methods under ignorable and non-ignorable missingness mechanisms. Given the inadequate attention to longitudinal studies with missing data, this study applied recent advances in missing data methods to repeated measures models and investigated the performance of various missing data methods, such as FIML (Full Information Maximum Likelihood Estimation) and MICE(Multivariate Imputation by Chained Equations), under MCAR, MAR, and MNAR mechanisms. Overall, the results showed that listwise deletion and mean imputation performed poorly compared to other recommended missing data procedures. The better performance of EM, FIML, and MICE was more noticeable under MAR compared to MCAR. With the non-ignorable missing data, this study showed that missing data methods did not perform well. In particular, this problem was noticeable in slope-related estimates. Therefore, this study suggests that if missing data are suspected to be non-ignorable, developmental research may underestimate true rates of change over the life course. This study also suggests that bias from non-ignorable missing data can be substantially reduced by considering rich information from variables related to missingness.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.27 no.5
• /
• pp.629-635
• /
• 2009

Collapses of cutting area have frequently occurred due to heavy rainfall caused by the recent unusual weather patterns. Collapses of cutting area have the most crucial influence on the damaged property and casualties. Therefore, formulating and preparing an effective measures and control system is urgent. For this reason, in this study, we researched formation investigation method of location-based cutting area for an efficient management of cutting area. We conducted comparative and analytic research on the hand GPS method and DGPS method which is GPS augmentation system, using SBAS signals. The results of the research showed that there was difficult in discerning the accurate shape of cutting area when the existing method was used; however, the detecting the shape of four sides and accurate location was possible when DGPS was used. Consequently, it is possible to establish a preventive measures for cutting area, which considers the condition of the surrounding environment of cutting area because the polygon based management of incision cliff is attainable, apart from the existing control point based approach.

• Proceedings of the Korean Information Science Society Conference
• /
• 2004.10b
• /
• pp.718-720
• /
• 2004

일반적으로 카메라는 좁은 시각 영역(field of view)를 가짐으로 인해, 넓은 영역의 뷰를 얻기 위해서는 모터를 이용하여 카메라를 팬/틸트시키는 것이 일반적이다. 하지만, 이들은 아직까지 기계적으로 카메라를 직접 움직여 원하는 영역의 영상을 보여주기 때문에, 내구성이 떨어지며 생산 원가도 많이 든다. 또한 움직임으로 인한 모션 블러 현상도 나타난다. 본 논문에서는 한번에 보은 지역을 촬영할 수 있고, 비기계적으로 팬/틸트가 가능한 카메라 시스템을 개발하고자 한다. 한번의 촬영으로 널은 영역을 얻기 위해, 어안렌즈를 CCD 센서와 항께 사용한다. 또한, 어안렌즈(fish-eye lens)를 통해 얻은 왜곡된 영상을 와핑 기술을 이용해 편 다음, 원하는 부분의 영상을 보여준다. 본 논문은 TI사의 TMS320DSC25 프로세서로 구현하였으며, 어안 렌즈 캘리브레이션 및 실시간 왜곡 보정, 영상 출력을 위한 방법을 소개한다.