• Journal of the Korean earth science society
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• v.35 no.2
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• pp.97-103
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• 2014

An isotopic hydrograph separation technique has been able to determine the contribution of new water (event water such as rain or snowmelt) and old water (pre-event water like groundwater) to a stream hydrograph for last several decades using stable water isotopes. It is based on the assumption that the isotopic compositions of both new water and old water at a given instant in time are known and the stream water is a mixture of the two waters. In this study, we show that there is a systematic error (standard error in the new water fraction) in the isotopic hydrograph separation if the average isotopic compositions of new water were used ignoring the temporal variations of those of new water. The standard error in the new water fraction is caused by: (1) the isotopic difference between the average value and temporal variations of new water; (2) the new water fraction as runoff contributing to the stream during rainfall or spring melt; and (3) the isotopic differences between new and old water (inversely). The standard error is large, in particular, when new water dominates the stream flow, such as runoff during intense rainfall and in areas of low infiltration during spring melt. To reduce the error in the isotopic hydrograph separation, incorporation of fractionation in the isotopic composition of new water observed at a point should be considered with simultaneous sampling of new water, old water and stream water.

• Journal of Aerospace System Engineering
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• v.10 no.4
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• pp.35-40
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• 2016

Mid-course correction maneuvers (MCCMs) are necessary to correct the launch-vehicle dispersion to go to the Moon. There were 3 or 4 MCCMs needed for a direct transfer trajectory. But the strategy for MCCMs of the phasing-loop trajectory is different, because it has a longer trans-lunar trajectory than direct transfer does. An orbiter using a phasing-loop trajectory has several rotations of the Earth, so the orbiter has several good places, such as perigee and apogee, to correct the launch-vehicle dispersion. Although launch dispersion is relatively high, the launch vehicle is not as accurate as we expected. A good MCCM strategy can overcome the high dispersion by using small-magnitude correction maneuvers. This paper describes the phasing-loops sequence and strategy to correct high launch-vehicle dispersions.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.13 no.1
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• pp.78-84
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• 2014

The rotation of a spindle unit must be accurate for high-quality machining and to improve the quality of the machine tools.Therefore, the proper measurement of the rotation accuracy and ensuring a proper analysis are very important. Separate processes are necessary because spindle errors and roundness errors associated with the test balls can both factor into the measured rotation error values. We used three methods to discern test ball errors and analyzed which could be deemed as the most proper technique in a test of the rotation accuracy of the main spindle of a machine tool.

• The Korean Journal of Applied Statistics
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• v.17 no.1
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• pp.75-88
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• 2004

The Support Vector Machine(SVM) algorithm has paid attention on maximizing the shortest distance between sample points and discrimination hyperplane. This paper suggests the total margin algorithm which considers the distance between all data points and the separating hyperplane. The method extends existing support vector machine algorithm. In addition, this newly proposed method improves the generalization error bound. Numerical experiments show that the total margin algorithm provides good performance, comparing with the previous methods.

• The Korean Journal of Petroleum Geology
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• v.12 no.1
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• pp.9-13
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• 2006

Volcanic glass shard, which shows relatively homogeneous chemical composition in volcanic eruption materials, is used to determine ages of tephra layers and then to correlate tephra layers each other for understanding of evolution of Quaternary geomorphology. For reducing processing errors in age determination and correlation of units, amorphous glass shard should be separated carefully from soil sample through laboratory procedures such as washing, separation, and identification. Introduction of these processes in detail could be reduced errors in tephrochronology by using volcanic glass shard.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.4 no.3
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• pp.139-145
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• 1992

In this paper, a technique to separate the incident and reflected waves in the flume tests is investigated. Using a least squares method, the separation technique has been formulated systematically. This method is applicable to the regular and irregular wave conditions. To illustrate its validity and applicability, numerical experiments have been carried out for both regular and irregular wave conditions. It was found that the method gives perfect results for the conditions without signal noises, and yields reasonable results even for the conditions with 30% signal noises of incident wave height. Hydraulic experiments have been also performed to prove its applicability of the method for real situations.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.271-274
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• 2002

본 논문에서는 초기 부호책 설계 방법으로 가장 널리 사용되는 이분 미소분리 방법의 성능 개선과 설계시간을 단축하기 위한 새로운 알고리즘을 제안한다. 성능 개선을 위해 학습벡터의 소속수가 최소인 부호백터를 제거하고, 최대인 부호벡터를 미소분리하여 대체하는 방법을 적용하고, 모든 부호벡터와의 거리오차론 구하여 학습벡터의 소속 여부를 결정하는 기존 방법과는 달리, 전단계와 현재 단계의 소속 부호벡터와의 거리오차를 가지고 소속 여부를 결정함으로써 설계시간을 크게 단축할 수 있다.

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 1992.08a
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• pp.121-125
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• 1992

입사파와 반사파의 분리는 수리모형실험에 있어서 기본적이면서도 대단히 중요한 문제이다. 최근까지 개발된 분리기법으로는 Goda and Suzuki (1976)의 2점법과 Mansard and Funke (1980)의 3점범을 들 수 있다. 2점법은 두 지점에서의 파고를 관측하여 분리하는 기법으로 두 지점사이의 거리에 따라 해가 존재하지 않는 파랑조건이 존재하며 수조에서 발생되는 횡파, 비선형 파랑상호 간섭, signal noise, 측정오차 등에 민감한 단점이 있다.(중략)

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2000.11a
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• pp.21-21
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• 2000

Thrust Cut-Off 시스템은 로켓 발사체의 분리시의 충격에 의한 비행방향오차 및 비행거리를 감소하고 Pay-Load 부에 추진력을 증가시키고 분리된 추진 기관부의 낙하위치 예측을 용이하게 한다. 이와 같이 중요한 역할을 하게되는 Thrust Cut-Off 시스템에서 스냅링은 핵심적인 역할을 하게 된다. 정상적인 추진체의 작동 시에는 고압의 연소가스를 지탱하고 분리 시에는 쉽게 분리되어 연소가스를 역 분사 시켜야한다.(중략)

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1998.06a
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• pp.1089-1092
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• 1998