• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.1476-1481
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• 2009

최근 기상이변과 국지성 호우로 인한 홍수피해를 경감하기 위해 국가차원과 더불어 지역단위의 홍수방어대책이 많은 사업을 통해 제시되고 있다. 대표적인 예로 풍수해저감종합계획과 하천기본계획 등을 들 수 있는데 이러한 사업들은 실제 피해지역에 대한 원인과 대책을 제시함과 동시에 홍수 등의 피해가 예상되는 위험지역에 대해서도 그 원인과 대책을 제시해야한다. 따라서 피해발생이 예상되는 지역을 예측하고 그 원인을 찾는데 있어 최근 홍수범람해석에 대한 필요성이 점차적으로 증대되면서 다양한 해석모형과 프로그램들이 개발되었고 현재까지도 홍수범람분석에 관한 활발한 연구들이 이루어지고 있다. 그러나 홍수범람구역을 결정하기 위한 과정은 GIS Tool에 대한 이해도 부족, 원 자료의 부족, 지형 구축을 위한 자료생성의 어려움 등과 같은 다양한 문제점들을 내포하고 있다. 특히, 홍수범람구역의 결정을 위한 전산프로 그램의 기능향상은 점차 향상되는데 비해 지형구축 등과 같은 범람해석 프로세스 내에서 상당한 수작업이 요구되는 바 작업소요시간이 많이 요구되는 단점으로 인해 실무자들에게 널리 적용되는데 있어 걸림돌이 되고 있는 실정이다. 따라서 본 연구에서는 실무적 관점에서 홍수범람해석의 요구빈도가 높은 중소규모 자연하천을 대상으로 두가지 해석 기법을 통하여 홍수범람해석을 수행하여 해석 과정 및 결과 등을 비교하였다. 첫 번째 기법으로 홍수범람해석을 수행하는데 있어 실용성, 신속성 등이 고려된다고 판단되는 Civil 3D를 이용하여 수치지형도 및 측량자료와 같은 원 자료로부터 3D 지형을 구축하고 Civil 3D의 Extension 프로그램인 HEC-RAS Tool과 1차원 수리모형인 HEC-RAS를 전 후처리에 연계함으로서 각 대상유역별, 빈도별 홍수위에 따른 홍수범람구역과 수심 및 범람지역을 우선적으로 분석하였다. 두 번째 기법으로서 실무에서 주로 이용되고 있는 ArcGIS를 이용하여 3D 지형을 구축하고 Hydrologic Engineering Center (HEC)와 Environmental Systems Research Institute(ESRI)의 협력개발로 개발된 HEC-GeoRAS와 HEC-RAS 모형을 전 후처리에 연계하여 홍수범람해석을 수행하였다. 이들 두 가지 기법을 통한 홍수범람해석의 과정과 결과에 대해 정량적, 정성적 비교를 수행하였으며, 두 기법간의 차이점 및 효율성을 제시하였다. 본 연구의 결과는 보다 실용적이면서도 정밀한 홍수범람구역의 결정, 홍수범람 예상도 등의 재해지도 작성, 치수경제성 분석 등에 있어 도움이 될 것으로 판단된다.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.21 no.1
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• pp.27-36
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• 2003

Generally, the latest acquisition method of geo-spatial informations in urban area is executed by generation of digital elevation model (DEM) and digital ortho image by digital photogrammetry method which is used large scale photo image. However, the biggest problem of this method is coarse accuracy of DEM which is automatically generated by digital photogrammetry workstation system. The coarse accuracy of DEM caused geo-spatial information in urban area to reduce of accuracy. Therefore, this study is purposed to increase of DEM accuracy which is applied to method terrain classification in urban area. As the results of this study, the proposed method of this study which is increased to accuracy of DEM by classification of terrain is better than accuracy of DEM which is automatically generated by digital photogrammetry workstaion system. And, the edge detection method which is proposed by this study is established to capability of 3D digital mapping in urban area.

• East Asian mathematical journal
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• v.31 no.5
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• pp.707-716
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• 2015

We consider a queueing system with N-limited nonstop forwarding. In this queueing system, when the server breaks down, up to N customers can be serviced during the repair time. It can be used to model an assembly line consisting of several automatic stations and a manual backup station. Within the framework of $Geo^X/D/1$ queue, the matrix analytic approach is used to obtain the performance of the system. Some numerical examples are provided.

• Journal of Astronomy and Space Sciences
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• v.10 no.1
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• pp.17-27
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• 1993

The orbit characteristics and perturbation effects of an artificial satellite with critical inclination have been studied. The critical inclination problem in artificial satellite theory is treated as Ideal Resonance Problem(IRP). The KITSAT-1 satellite launched by Arian 42P at Guiana in August 11, 1992 has orbital inclination close to the critical value cos-1(1/√5). In that case, there is a singularity in some perturbation terms and perigee of the orbit is fixed because d$\omega$/dt is theoretically equal to zero. But actually the long periodic behaviour in argument of perigee, $\omega$ shows a small oscillation. The causes of the oscillation and the relativistic effect in IRP have been studied and applied to the KITSAT-1. The geo-potential perturbation terms which are seperated inclination terms have been obtained using Algebraic manipulation. Also luni-solar disturbing funtion based on the relative position of the sun, moon, and satellite has been obtained. Phase portraits are used to depict the change of eccentricity and grgument of perigee. The variations of each orbital elements have been obtained in case of the KITSAT-1.

• Journal of Advanced Navigation Technology
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• v.28 no.5
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• pp.588-593
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• 2024

Korea augmentation satellite system (KASS), KASS training and test platform (KTTP) was developed for KASS operator and maintainer training and KASS system verification, and it is an independently operated system. KTTP has one each of KASS reference station (KRS), KASS processing station (KPS), KASS uplink station (KUS), network bench, geostationary earth orbit (GEO) simulator and added the one central monitoring & control simulator (CMS) to switch the master operation mode to backup. Hardware and software of KTTP are identical to the KASS system. Therefore, the area where KTTP is installed must be verified through site infrastructure acceptance review (SIAR) in the same way as the KASS system. KTTP Verification is based on the KASS system integration, verification, qualification (IVQ) procedure, and verification was completed with a focus on the functionality rather than performance.

• Geophysics and Geophysical Exploration
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• v.7 no.1
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• pp.56-61
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• 2004

In order to image the distribution of permeability in granitic rocks, we carried out two-dimensional (2D) resistivity profiling, together with in-situ permeability tests, electrical logging of boreholes, and resistivity measurements of rock core samples in a laboratory. Based on the electrical logging and in-situ permeability data from boreholes, we obtained empirical equations which relate resistivity and permeability of the granitic rocks in the area studied. We then applied the empirical equation to a 2D resistivity section, to produce a 2D permeability section of the granitic rocks. In this paper, we present details of the field data and of the procedure for conversion from the resistivity section to a permeability section. The observed relationship between resistivity and permeability of the rocks is also discussed.

• Journal of the Korean GEO-environmental Society
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• v.14 no.5
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• pp.23-32
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• 2013

This paper presents the effect of pile diameter on the lateral behavior of offshore pile for wind turbine. The material parameters of the soils were estimated through SPT on the Southwestern offshore area in Korea, where the first wind farm is planned. The FDM software, FLAC3D, and LPile were adopted to derive the load-displacement curve, p-y curve, and maximum bending moment at a specified displacement. It was found that the results from softwares significantly differ and the LPile could overestimate the allowable capacity. The maximum bending moment along the pile with 2m diameter could be as large as four times the bending moment with 1m diameter. Similar trend was observed for the allowable lateral capacity.

• Journal of Korea Society of Industrial Information Systems
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• v.23 no.2
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• pp.29-39
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• 2018

In this paper, we discuss a discrete-time queueing system with dyadic server control policy that combines workload control and multiple vacations. Customers arrive at the system with Bernoulli arrival process. If there is no customer to serve in the system, an idle single server spends a vacation of discrete random variable V and returns. The server repeats the vacation until the total service time of waiting customers exceeds the predetermined workload threshold D. In this paper, we derived the steady-state workload distribution of a discrete-time queueing system which is operating under a more realistic and flexible server control policy. Mean workload is also derived as a performance measure. The results are basis for the analysis of system performance measures such as queue lengths, waiting time, and sojourn time.

• Journal of the Korean GEO-environmental Society
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• v.15 no.6
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• pp.31-39
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• 2014

The objective of this study is to suggest the proper sediment transport equation and short and long-term bed change for planning and implementing the river management in Korea. To analyze total sediment discharge and short and long-term bed change, existing sediment transport equations, HEC-RAS 4.1 and CCHE2D numerical models were applied in urban and mountainous rivers. The results of this study are as followings; Firstly, the modified Einstein equation showed the most appropriate result for the estimation of total sediment discharge in the local rivers. Secondly, The stage-discharge relation curve and the discharge-total sediment discharge relation curve were suggested to examine the characteristics of river bed change. Finally, it is founded that river bed change of mountainous river has occurred greater than that of the urban river, and the river bed of urban river now tends to be stabilized on the whole.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.1D
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• pp.153-160
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• 2009

In relation to digital elevation model(DEM) production using high resolution satellite imagery, existing studies present that DEM accuracy differently show according to land cover property. This study therefore proposes auto-selection method of window size for correlation matching according to land cover property of IKONOS Geo-level stereo image. For this, land cover classified image is obtained by IKONOS color image with four bands. In addition, correlation-coefficients are computed at regular intervals in pixels of the window-search area to shorten of matching time. As the results, DEM by the proposed method showed more accurate than DEM using the fixed window-size matching. We estimate that accuracy of the proposed DEM improved more than DEM by digital map and ERDAS in agricultural land.