• The Korean Journal of Applied Statistics
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• v.27 no.3
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• pp.475-485
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• 2014

A stochastic weather generator based on a generalized linear model (GLM) approach is a commonly used tools to simulate a time series of daily weather. In this paper, we propose a multi-site weather generator with applications to historical data in South Korea. The proposed method extends the approach of Kim et al. (2012) by considering spatial dependence in the model. To reduce this phenomenon, we also incorporate a time series of seasonal mean precipitations of South Korea in the GLM weather generator as a covariate. Spatial dependence was incorporated into the model through a latent Gaussian process. We apply the proposed model to precipitation data provided by 62 stations in Korea from 1973{2011.

• Geophysics and Geophysical Exploration
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• v.16 no.4
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• pp.293-299
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• 2013

The recent Multiple Lapse Time Window (MLTW) analysis of Korean Peninsula event showed that the focal depth was far greater influence factor than the velocity structure of the model, applying the analysis of the direct simulation Monte Carlo (DSMC) method. Thus, using the events with focal depth of about 10 km, this study considered 330 paths connecting 41 events and 71 stations, and re-examined uniform and depth-dependent velocity models previously studied. As a result, the residual of misfit function greatly decrease from analytic model to DSMC model, reflecting variation of the focal depth from 0 to 10 km. On the other hand, the difference of residuals for each velocity model were relatively small.

• Water for future
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• v.26 no.3
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• pp.75-85
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• 1993

In this study, reach boundaries in QUAL2E Model were set by the locations of point-waste discharge or tributary input and measured or direct calculated hydrologic factors were used in computation as much as possible. South Platte Experimental River in Colorado, USA was selected as a target river and data collected during September 1991 and January 1992 periods were used for calibration and verification, respectively. Constituents modeled in this study are 5-day carbonaceous biochemical oxygen demand(CBOD$) and dissolved oxygen(DO). The good agreement was obtained between a calculated using this model and observed, less than 5% to DO and about 20% to CBOD$. According to the result of water-quality prediction, experimental river is classified as the 4th category by the criteria of environmental protection agency in the USA in 2001.

• Water for future
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• v.14 no.1
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• pp.51-58
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• 1981

This study attempts to examine and estabilish a simulation model from the stochastic analysis of daily streamflow. Daily streamflow records obstained at the main gauging stations along the Han, Nakdong and Geum River were used in the analysis. The following results were abtained. From the analysis of time series of streamflow by the correlogram and spectraal density, The serial component of one-year periodicity, serial correlation and irregular or random component were found. The coefficient of determination R2 of multilag model remaine a plateau at log-two, so that second order mu.ltilag model was Known to fit in the simulation of daily streamflow, Consequently, multilag and recised Markov model of the sewnd order give the best results in simulatin of daily streamflow. But the former generally gives better results than the latter. And theoretical markev model is unfit in the simulation of daily series without modification.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.178-183
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• 2008

지구온난화로 인한 기후변화가 기정사실화 되면서 이러한 기후변화에 대비하기 위한 다양한 연구가 진행중이다. 수자원과 관련된 기후변화 연구를 살펴보면 초기에는 장기적 관점에서 기후변화가 유출에 미치는 영향에 대한 연구가 대부분을 이루고 있었으나 2003년을 기점으로 유럽을 중심으로 기후변화가 홍수량에 미치는 영향에 대한 연구가 시작되었다. 기후변화가 홍수에 미치는 영향을 평가하는데 가장 중요한 것은 수문시계열 자료의 해상도라고 할 수 있다. 이러한 시공간적 해상도 문제를 해결하기 위해서 세계 각국은 각국의 상황에 맞는 RCM을 개발하고 있으며 자국에 적합한 축소기법을 개발하고자 노력하고 있다. 따라서 본 연구에서는 고해상도 수문기상자료의 생성을 위하여 기후변화 모형으로부터 생성된 일 단위 강우자료를 시자료로 분해하기 위한 기법을 제시하고자한다. 지난 수십년 동안 강우나 기타 수문시계열 자료를 다양한 해상도의 자료로 변환하기 위한 연구가 진행되어왔다. 그러나 이러한 연구의 가장 큰 한계점은 대부분의 시계열 자료가 추계학적 특성을 가지고 있다고 가정한 후, 분석을 진행했다는 것이다. 이렇게 되면 강우발생에 따른 물리적 과정을 모형의 구조에 반영하는데 한계점을 드러내게 된다. 따라서 본 연구에서는 해상도를 변화시키는데 따른 강우의 운동역학적 특성을 고려하기 위하여 카오스를 기반으로 한 분해기법을 제시하고자 한다. 우선 카오스 분석을 통해서 지점 강우자료의 카오스 특성을 확인한 후, 현재까지 관측된 강우를 기반으로 $2CO_2$에서의 일 강우를 일 단위 보다 작은 단위로 분해하였다.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.2061-2065
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• 2008

본 연구는 강우-유출 및 TOC의 패턴 분류를 위하여 광주 광산 강우관측소의 강우량자료와 나주지점의 유출량 그리고 기존의 BOD 및 COD 수질농도 측정값에 비하여 적은 오차요인과 빠른 시간에 결과 값을 얻을 수 있으며 유출량과 난분해성 물질에 대한 해석이 가능하고 재현성이 탁월한 TOC자료를 사용하였다. SOM을 적용하기 위해 먼저 Map의 크기는 Garcia가 제시한 $M=5{\sqrt{N}}$을 이용하여 결정한다. 이러한 비선형적인 다변량 자료를 분석하기 위해서 Map에 의해 구분된 자료 위치를 추출하여 원자료를 재구축하고 이를 통해 원자료를 패턴별로 분류 할 수 있었다. 이러한 패턴별 분류를 통해 유출량에 따른 TOC자료를 2차원의 Map 상에 시각적으로 가시화하여 비선형적인 경향이 강한자료의 분포적 양상을 이해하는데 큰 도움이 되며, 향후 이를 통해 예측을 위한 모형화 과정에도 크게 도움을 줄 것으로 기대된다. 또한, 강우자료 또는 유출량 자료만을 이용한 단일변량의 패턴분류를 위해 SOM의 적용이 가능할 것으로 판단되며, 이는 각 변량의 본질적인 특성을 파악할 수 있을 것으로 기대된다.

• Korean Journal of Optics and Photonics
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• v.8 no.2
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• pp.107-110
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• 1997

We generated a diffraction free beam from Nd:YAG laser with an NBUR (negative branch unstable ring) resonator. The field inside the resonator had a plane wavefront and a homogeneous intensity distribution and the output beam through a scraper mirror of an annular type was used as a source. The outpur beam had an inner radius of 2.5 mm and an outer radius of 5 mm. In this experiment, we used a Fourier transformation lens with the focal length of 5 m to observe the far-field pattern. The lens was placed at a distance of the focal length from the scraper mirror and we found that the beam did not show any noticable diffraction over the distance of 13 m from the lens.

• Journal of the Korean Geographical Society
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• v.41 no.1 s.112
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• pp.94-105
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• 2006

This paper aims to analyze changes of unusual temperature events on summer and winter and their controlling factors. There has been obviously an increased frequencies of summer unusual high temperature occurrence and decreased frequencies of winter unusual low temperature at most of stations. WMI, winter SHI and AOI might be essential for prediction of unusual temperature during winter and summer OHI and spring NPI for summer unusual low temperature. These factors are crucial because they reflect the recent global warming trend as well as have apparent associations with unusual temperature occurrence frequency in Korea.

• Journal of the Korean Geotechnical Society
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• v.15 no.5
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• pp.141-155
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• 1999

Korea Ocean Research & Development Institute(KORDI) conducted an offshore geotechnical investigation for the Eardo Ocean Research Station with the help of the Fugro International Limited at a site location approximately 152 km away from Mara Island, Korea. The primary purpose of the geotechnical investigation was to obtain information on soil and foundation conditions, and to develop foundation design data for a fixed offshore observation platform. This paper discussed the details of the geotechnical investigation and the foundation design recommendations for the Ocean Research Station. Clear recommendations were proposed for the foundation type of driven pile considering the existing soil conditions.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.12 no.2
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• pp.141-150
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• 1992

In this study, six gaging stations(T/M bureau) in the Han River basin were selected for flood frequency analysis and was carried out frequency analysis by POT(peaks Over a Threshold) model where existing flood data of short record length are available. Frequency and magnitudes of each station floods in the river basins were estimated by POT model based on statistical method, and also were compared with standard errors to verify applicability of the estimates by POT model. Furthermore, in order to evaluate for the adequate design flood which is needed for the design of the hydrologic structures in the ungaged watersheds, it is considered to be possible to develop the statistical regionalized model by regional frequency analysis.