• 수면정신생리
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• 제11권2호
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• pp.80-83
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• 2004

목 적：수면잠복기 반복검사(Multiple sleep latency test, MSLT)는 주간 졸림증을 측정하는 객관적 방법으로 현재 가장 널리 쓰이고 있다. 미국 수면학회의 MSLT guideline에서는 수면의 시작을 최소 1개 epoch의 1단계 수면으로 정의하고 있으나 여전히 상당수의 수면센터에서는 수면의 시작을 위해 3개 epoch 이상의 1단계수면을 요구하고 있다. 본 연구는 두가지 다른 기준의 적용에 의해 수면잠복기반복검사의 결과에 어느 정도의 차이가 발생하는지를 확인하고 보다 타당한 수면시작기준을 알아보고자 한다. 방 법：1999년 4월부터 2004년 7월까지 고려대병원 수면다원검사실에서 시행한 수면잠복기 반복검사중 60건(300 nap)의 수면잠복기 반복검사기록을 후향적으로 조사하였다. 동일한 수면잠복기 반복검사기록을 각기 1개 epoch 기준과 3개 epoch 기준을 적용하여 수면잠복기를 기록후 이를 통계적 방법으로 비교하였다. 결 과：전체 60명의 MSLT 중 수면시작의 기준을 달리 적용했을때 평균 수면잠복기 결과가 달라진 경우는 20명으로 33.3%였으며 3개 epoch 기준에 비해 1개 epoch 기준을 적용시 단축되는 평균수면잠복기의 변화율은 최소 1.3%에서 최대 38.5%으로 평균값은 15.9%였지만 통계적으로 의미있는 차이는 아니였으며 수면잠복기가 상대적으로 긴비기면병군이 기면병군에 비해 변화가 발생하는 비율이 더 높았다. 결 론：다른 수면시작기준의 적용에 따라 수면잠복기결과의 변화가 나타났으나 졸림증의 정도가 중등도이상인 경우 그차이는 통계적으로 의미있는 것은 아니였다. 하지만 임상적으로 의미있는 졸리움을 보다 민감하게 측정할 수 있는 기준이라는 측면에서는 1개 이포크기준이 보다 타당할 수 있겠다.

• Journal of Positioning, Navigation, and Timing
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• 제3권3호
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• pp.117-122
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• 2014

In CDGPS, ambiguity resolution is determined by the performance of a floating solution, and thus, the performance needs to be improved. In the case of precise positioning at a stationary position, the batch method using multiple measurements is used for the accuracy improvement of a position. The position accuracy performance of a floating solution is outstanding, but it has a problem of high computation cost because all measurements are used. In this study, to improve the floating solution performance of the initial static user in CDGPS, a floating solution method using a recursive filter was implemented. A recursive filter estimates the position solution of the current epoch using the position solution of up to the previous epoch and the pseudorange measurement of the current epoch. The computation cost of the floating solution method using a recursive filter was found to be similar to that of the epoch-by-epoch method. Also, based on actual GPS signals, the floating solution performance was found to be similar to that of the batch method. The floating solution using a recursive filter could significantly improve the performance of the prompt initial position and ambiguity resolution of the initial static user.

• 디지털콘텐츠학회 논문지
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• 제10권2호
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• pp.225-231
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• 2009

디지털 문화유산의 활용범위가 확대 되면서, 국내에서도 체계화된 디지털 문화유산 연구가 필요하게 되었다. 유럽에서 진행된 EPOCH 프로젝트는 디지털 문화유산 연구의 표준화 작업, 기술과 역사학 간의 학제간 연계 증진 방안 연구, 디지털 문화유산의 실질적인 활용방안 모색 등의 결과를 이루었다. 이를 경영 기술 문화 영역에서 분석함으로서 앞으로 진행될 디지털 문화유산 프로젝트의 방향을 발견할 수 있었다. 본 논문에서는 정책분야에서 디지털 문화유산의 독립적인 연구 분야 확립과 박물관의 민간 자본 투입을 제안하고, 연구 분야에서는 맞춤형 기술을, 그리고 경영학 측면에서의 연구 필요성 등을 제안한다.

• Wind and Structures
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• 제9권3호
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• pp.179-191
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• 2006

Parent wind data are often acknowledged to fit a Weibull probability distribution, implying that wind epoch maxima should fall into the domain of attraction of the Gumbel (Type I) extreme value distribution. However, observations of wind epoch maxima are not fitted well by this distribution and a Generalised Extreme Value (GEV) analysis leading to a Type III fit empirically appears to be better. Thus there is an apparent paradox. The reasons why advocates of the GEV approach seem to prefer it are briefly summarised. This paper gives a detailed analysis of the errors involved when the GEV is fitted to epoch maxima of Weibull origin. It is shown that the results in terms of the shape parameter are an artefact of these errors. The errors are unavoidable with the present sample sizes. If proper significance tests are applied, then the null hypothesis of a Type I fit, as predicted by theory, will almost always be retained. The GEV leads to an unacceptable ambiguity in defining design loads. For these reasons, it is concluded that the GEV approach does not seem to be a sensible option.

• Management Science and Financial Engineering
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• 제9권2호
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• pp.1-12
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• 2003

For a stationary queue with BMAP arrivals, Takine and Takahashi [8] present a relationship between the queue length distributions at a random epoch and at a departure epoch by using the rate conservation law of Miyazawa [6]. In this note, we derive the same relationship by using the elementary balance equation, ‘rate-in = rate-out’. Along the same lines, we additionally derive relationships between the queue length distributions at a random epoch and at an arrival epoch. All these relationships hold for a broad class of finite-as well as infinite-capacity queues with BMAP arrivals.

• Journal of Contemporary Eastern Asia
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• 제20권2호
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• pp.138-156
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• 2021

The aim of this article is to describe direction of Sino-Russian relations toward a new epoch - as the decision-making centers of both countries define them - indicating the commitment to building the future international order. It includes the synthesis of evolution of relations, descriptions of cooperation building of mutual confidence by both sides in variety of institutions; analyses of geo-economic relations emphasizing their geostrategic dimension and finally dynamics showing how two great powers want to achieve new areas of cooperation focused on building multipolar world order which is the essence of "new epoch". The argument goes towards recognizing the relationship as a "hhybrid alliance". This hybridity is a structural factor that can constrain the use of new dimensions of asymmetric interdependence as political leverage especially by United States against the two non-western powers but also facilitate to use it against West.

• 한국측량학회:학술대회논문집
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• 한국측량학회 2002년도 추계학술발표회 논문집
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• pp.63-66
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• 2002

• 한국측량학회지
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• 제35권6호
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• pp.573-580
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• 2017

GPS 관측값을 이용하여 측위를 하는 경우 조정계산이 수반되면 이때 관측오차에 대한 정확한 모델링이 필수적이다. 본 연구에서는 GPS 관측타입별 관측오차를 분석하기 위해 MINQUE(Minimum Norm Quadratic Unbiased Estimators) 방법을 사용하였으며 단기선 GPS측위 모델을 기반으로 하였다. C1, P2, L1, L2 관측타입에 대해 각각 단위분산을 계산하였으며 그 결과 관측오차는 각각 22.3cm, 27.6cm, 2.5cm, 2.2cm로 나타났다. 단위분산 계산에는 대용량의 컴퓨터 메모리와 복잡한 계산이 필요하다. 이러한 단점을 극복하기 위해 epoch별로 단위분산을 추정하였으며 결과를 분석함으로써 epoch별 계산방법의 유효성을 검증하였다. 분석 결과, 계산된 결과값에 차이가 있긴 했으나 그 차이가 비교적 작기 때문에 대부분의 GPS 응용분야에서의 활용에는 문제가 없을 것으로 판단된다.

• 천문학회보
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• 제41권2호
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• pp.33.1-33.1
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• 2016

We report detection of short-term flux variability in multi-epoch observations and intraday variability in polarized emission at millimeter-wavelength from S5 0716+714 using Korean VLBI Network (KVN) radio telescopes. Over the whole observation epochs, the source shows significant inter-month variations at K- and Q-band with modulation indices of 19% at K-band and 36% at Q-band. In each epoch, the source shows monotonic flux increase in Epoch 1 and 3, and monotonic flux decrease in Epoch 2 and 4. We found an inverted spectrum with mean spectral indices of -0.57 in Epoch 1 and -0.15 in Epoch. On the contrary, we found relatively steep indices of 0.24 and 0.17 in Epoch 2 and Epoch 4, respectively. In the study of intraday variability of polarization, we found significant variations in the degree of linear polarization at 86 GHz, and in polarization angle at 43 and 86 GHz during ~10 h. The spectrum of the source is quite flat with spectral indices of -0.07 to 0.07 at 22-43 GHz and -0.23 to 0.04 at 43-86 GHz. The measured degree of the linear polarization ranges from 2.3% to 3.3 % at 22 GHz, from 0.9% to 2.2 % at 43 GHz and from 0.4 % to 4.0 % at 86 GHz, yielding prominent variations at 86 GHz over 4-5 h. The linear polarization angle is in the range of 4 to $12^{\circ}$ at 22 GHz, -39 to $81^{\circ}$ at 43 GHz, and 66 to 119 at 86 GHz with a maximum rotation of $110^{\circ}$ at 43 GHz over ~4 h. We estimated the Faraday rotation measures (RM) ranging from -9200 to 6300 rad m-2 between 22 and 43 GHz, and from -71000 to 7300 rad m-2 between 43 and 86 GHz, respectively. The frequency dependency of RM was investigated, yielding a mean power-law index, a, of 2.0. This implies that the polarized emission from S5 0716+714 at 22-86 GHz moves through a Faraday screen in or near the jet of the source.

• 천문학회지
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• 제56권2호
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• pp.137-147
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• 2023

Shoushili was the official calendrical method promulgated in 1280 CE by the Yuan dynasty. It contains a list of the angular spans in right ascensions for the 28 lunar lodges. They are known to have been measured by Guo Shoujing with his advanced instruments with an unprecedented precision or reading error of 5'. Such precise data are useful to determine their observational epoch with an error range which is narrow enough to pinpoint on which historical occasion they were observed. Using the precise SIMBAD data based on eDR3 of GAIA and carefully identified determinative stars and considering the precession of equinoxes and proper motions, we apply linear regression methods to those data and obtain the observational epoch of 1271 ± 16 CE and the measurement error of 4.1'. We also have polar distances corresponding to declinations written in another manuscript of the Ming dynasty. Since the two data sets have similar significant digits, they were suggested to have the same origin. However, we obtain their observational epoch of 1364±5 CE and the measurement error of 5.7'. They must have been measured with different instruments and on a different occasion from the observations related to Shoushili. We review the history of the calendrical reform during the 13th century in the Yuan dynasty. We conclude that the observational epoch obtained from lodge spans in Shoushili agrees with the period of observations led by Guo Shoujing or 1276-1279 CE, which is also supported by the fact that the ecliptic lodge span values listed in Shoushili were calculated from the equatorial lodge spans.