• Title/Summary/Keyword: 모의기반

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Improvement of turbid water prediction accuracy using sensor-based monitoring data in Imha Dam reservoir (센서 기반 모니터링 자료를 활용한 임하댐 저수지 탁수 예측 정확도 개선)

  • Kim, Jongmin;Lee, Sang Ung;Kwon, Siyoon;Chung, Se Woong;Kim, Young Do
    • Journal of Korea Water Resources Association
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    • v.55 no.11
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    • pp.931-939
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    • 2022
  • In Korea, about two-thirds of the precipitation is concentrated in the summer season, so the problem of turbidity in the summer flood season varies from year to year. Concentrated rainfall due to abnormal rainfall and extreme weather is on the rise. The inflow of turbidity caused a sudden increase in turbidity in the water, causing a problem of turbidity in the dam reservoir. In particular, in Korea, where rivers and dam reservoirs are used for most of the annual average water consumption, if turbidity problems are prolonged, social and environmental problems such as agriculture, industry, and aquatic ecosystems in downstream areas will occur. In order to cope with such turbidity prediction, research on turbidity modeling is being actively conducted. Flow rate, water temperature, and SS data are required to model turbid water. To this end, the national measurement network measures turbidity by measuring SS in rivers and dam reservoirs, but there is a limitation in that the data resolution is low due to insufficient facilities. However, there is an unmeasured period depending on each dam and weather conditions. As a sensor for measuring turbidity, there are Optical Backscatter Sensor (OBS) and YSI, and a sensor for measuring SS uses equipment such as Laser In-Situ Scattering and Transmissometry (LISST). However, in the case of such a high-tech sensor, there is a limit due to the stability of the equipment. Therefore, there is an unmeasured period through analysis based on the acquired flow rate, water temperature, SS, and turbidity data, so it is necessary to develop a relational expression to calculate the SS used for the input data. In this study, the AEM3D model used in the Water Resources Corporation SURIAN system was used to improve the accuracy of prediction of turbidity through the turbidity-SS relationship developed based on the measurement data near the dam outlet.

A Disk Group Commit Protocol for Main-Memory Database Systems (주기억 장치 데이타베이스 시스템을 위한 디스크 그룹 완료 프로토콜)

  • 이인선;염헌영
    • Journal of KIISE:Databases
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    • v.31 no.5
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    • pp.516-526
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    • 2004
  • Main-Memory DataBase(MMDB) system where all the data reside on the main memory shows tremendous performance boost since it does not need any disk access during the transaction processing. Since MMDB still needs disk logging for transaction commit, it has become another bottleneck for the transaction throughput and the commit protocol should be examined carefully. There have been several attempts to reduce the logging overhead. The pre-commit and group commit are two well known techniques which do not require additional hardware. However, there has not been any research to analyze their effect on MMDB system. In this paper, we identify the possibility of deadlock resulting from the group commit and propose the disk group commit protocol which can be readily deployed. Using extensive simulation, we have shown that the group commit is effective on improving the MMDB transaction performance and the proposed disk group commit almost always outperform carefully tuned group commit. Also, we note that the pre-commit does not have any effect when used alone but shows some improvement if used in conjunction with the group commit.

A Sliding Mode Control of an Underwater Robotic Vehicle under the Influence of Thrust Dynamics (추진기의 동역학을 고려한 무인잠수정의 슬라이딩 모드 제어)

  • Choi, Hyeung-Sik;Park, Han-Il;Roh, Min-Shik;So, Myung-Ok
    • Journal of Advanced Marine Engineering and Technology
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    • v.33 no.8
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    • pp.1203-1211
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    • 2009
  • The dynamics of underwater vehicles can be greatly influenced by the dynamics of the vehicle thrusters. The control of the state of the hovering or very slow motion of the underwater vehicle is most important for automatic docking or control of the manipulator of the vehicle. The dynamics of the thruster based on the electric motor is nonlinear and has uncertain parameters. Since the dynamics of the vehicle coupled with the dynamics of the thruster is nonlinear and has uncertain parameters, a robust control is very effective for a desired motion tracking of the uncertain and nonlinear vehicle. In this paper a study was performed on the robust control scheme of the very slow motion or hovering motion of the underwater vehicle actuated by the electric motor. Also, a concurrent control on the state of the vehicle with nonlinearity and uncertain parameters was performed. A sliding mode control algorithm out of robust controllers was designed and applied, which compensates the nonlinear forces and uncertain parameters of the vehicle and actuator. Through a computer simulation, the proposed control scheme was compared with a linear PD controller and its superior performance was validated.

Modeling of Earthquake Ground Motion in a Small-Scale Basin (소규모 분지에서의 지진 지반운동 모델링)

  • Kang, Tae-Seob
    • Geophysics and Geophysical Exploration
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    • v.15 no.2
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    • pp.92-101
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    • 2012
  • Three-dimensional finite-difference simulation in a small-scale half-sphere basin with planar free-surface is performed for an arbitrary shear-dislocation point source. A new scheme to deal with free-surface boundary condition is presented. Then basin parameters are examined to understand main characteristics on ground-motion response in the basin. To analyze the frequency content of ground motion in the basin, spectral amplitudes are compared with each other for four sites inside and outside the basin. Also particle motions for those sites are examined to find which kind of wave plays a dominant role in ground-motion response. The results show that seismic energy is concentrated on a marginal area of the basin far from the source. This focusing effect is mainly due to constructive interference of the direct Swave with basin-edge induced surface waves. Also, ground-motion amplification over the deepest part of the basin is relatively lower than that above shallow basin edge. In the small-scale basin with relatively simple bedrock interface, therefore, the ground-motion amplification may be more related to the source azimuth or direction of the incident waves into the basin rather than depth of it.

Color-Texture Image Watermarking Algorithm Based on Texture Analysis (텍스처 분석 기반 칼라 텍스처 이미지 워터마킹 알고리즘)

  • Kang, Myeongsu;Nguyen, Truc Kim Thi;Nguyen, Dinh Van;Kim, Cheol-Hong;Kim, Jong-Myon
    • Journal of the Korea Society of Computer and Information
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    • v.18 no.4
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    • pp.35-43
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    • 2013
  • As texture images have become prevalent throughout a variety of industrial applications, copyright protection of these images has become important issues. For this reason, this paper proposes a color-texture image watermarking algorithm utilizing texture properties inherent in the image. The proposed algorithm selects suitable blocks to embed a watermark using the energy and homogeneity properties of the grey level co-occurrence matrices as inputs for the fuzzy c-means clustering algorithm. To embed the watermark, we first perform a discrete wavelet transform (DWT) on the selected blocks and choose one of DWT subbands. Then, we embed the watermark into discrete cosine transformed blocks with a gain factor. In this study, we also explore the effects of the DWT subbands and gain factors with respect to the imperceptibility and robustness against various watermarking attacks. Experimental results show that the proposed algorithm achieves higher peak signal-to-noise ratio values (47.66 dB to 48.04 dB) and lower M-SVD values (8.84 to 15.6) when we embedded a watermark into the HH band with a gain factor of 42, which means the proposed algorithm is good enough in terms of imperceptibility. In addition, the proposed algorithm guarantees robustness against various image processing attacks, such as noise addition, filtering, cropping, and JPEG compression yielding higher normalized correlation values (0.7193 to 1).

The Analysis of Suspended Sediment Load of Donghyang and Cheoncheon Basin using GIS-based SWAT Model (GIS 기반 SWAT 모델을 이용한 동향·천천유역의 부유사량 분석)

  • Lee, Geun-Sang;Kim, Yu-Ri;Ye, Lyeong;Lee, Eul-Rae
    • Journal of the Korean Association of Geographic Information Studies
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    • v.12 no.2
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    • pp.82-98
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    • 2009
  • This study applied SWAT model to analyze suspended sediment load that is influence on the high density turbid water in Donghyang and Cheoncheon basin, which are located in the upstream of Yongdam Dam. GIS data such as DEM, land cover map and soil map, and meteorological data were used as the input data of SWAT model. And the rating curve equation and Q-SS equation of Donghyang and Cheoncheon gauge station were applied as the measured values of them. As the result of flowout, the coefficient of determination (R2) and the Nash-Sutcliffe coefficient of efficiency (EI) of model calibration showed high as 0.87 and 0.87 at Donghyang gauge station, and the R2 and EI of model validation were high as 0.95 at Cheoncheon gauge station. Also, as the result of suspended sediment load, the R2 and EI of model calibration were high as 0.77 and 0.76 at Donghyang gauge station, and the R2 and EI of model validation marked high as 0.867 and 0.80 at Cheoncheon gauge station. It is considered that the suspended sediment load of 2003 showed the highest due to rainfall amounts and rainfall intensity in using SWAT model. The results of suspended sediment modeled in this study can be applied to the decision-making support data for the evaluation of soil erosion possibility and turbid water potential in the management of reservoir.

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A Study on the Transport of Soil Contaminant (A Development of FDM Model for 3-D Advection-Diffusion Equation with Decay Term) (토양 오염원의 이동에 관한 연구 (감쇠항이 있는 3차원 이송-확산 방정식의 수치모형 개발))

  • Kim, Sang-Jun
    • Journal of Korea Water Resources Association
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    • v.45 no.2
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    • pp.179-189
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    • 2012
  • To simulate the transport of pollutant, a numeric model for the advection-diffusion equation with the decay term is developed. This is finite-difference model using the implicit method (with the weight factor α) and Gauss-Seidel SOR(successive over-relaxation). This model is compared to the analytical solutions (of simpler dimensional or boundary conditions), and in the condition of Peclet number < 5~20, the result shows stable condition, and Crank-Nicolson method (α=0.5) shows the more accurate results than fully-implicit method (α=1). The mass of advection, diffusion and decay is calculated and the error of mass balance is less than 3%. This model can evaluate the 3-D concentrations of the advection-diffusion and decay problems, but this model uses only the finite-difference method with the fixd grid system, so it can be effectively used in the problems with small Peclet numbers like the pollutant transport in groundwater.

Experimental Study on Underwater Transient Noise Generated by Water-Entry Impact (입수 충격 수중 순간 소음에 대한 실험적 연구)

  • Jung, Youngcheol;Seong, Woojae;Lee, Keunhwa;Kim, Hyoungrok
    • The Journal of the Acoustical Society of Korea
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    • v.33 no.1
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    • pp.10-20
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    • 2014
  • To study the water-entry impact noise, on-board experiment using a small launcher firing various objects was performed in the Yellow Sea. As the launcher fires a cylindrical object from the ship vertically, generated noise is measured with a hydrophone on the starboard of Chung-hae, Marine surveyor. Three types of cylindrical objects, which have noses of flat-faced, conical, and hemisphere, were used during the experiment. The measured noise exhibits a time-dependency which can be divided into three phases: (1) initial impact phase, (2) open cavity flow phase, (3) cavity collapse and bubble oscillation phase. In most cases, the waveform of bubble oscillation phase is dominant rather than that of initial impact phase. Pinch-off time, where a cavity begins to collapse, occurs at 0.18 ~ 0.2 second and the average lasting time of bubble was 0.9 ~ 1.3 second. The energy of water-entry impact noise is focused in the frequency region lower than 100 Hz, and the generated noise is influenced by the nose shapes, object mass, and launching velocity. As a result, energy spectral density on the bubble frequency is higher in the order of flat-faced, conical, hemisphere nose, and the increase of initial energy raises the energy spectral density on the bubble frequency in the cylinder body of same shape. Finally, we compare the measurements with the simulated signals and spectrum based on the bubble explosion physics, and obtain satisfactory agreements between them.

Development of C2 Virtual Linked Simulator For Engineering and Engagement Level Battle Experimentation (공학-교전급 전투실험을 위한 C2 가상모의 연동 시뮬레이터 개발)

  • Lee, Sangtae;Lee, Seungyoung;Hwang, Kun-Chul;Kim, Saehwan;Lee, Kyuhyun
    • Journal of the Korea Society for Simulation
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    • v.22 no.4
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    • pp.11-19
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    • 2013
  • The Korean naval weapon systems, combat experiments establish the concept of Battle operations, and create the future of the new weapons system. Doctrine development and training as well as ranging from experiments for evaluate the performance of mission operations for combat experiments are used. The battle lab is effectively support tool for the Korean Naval battle experiments. The battle lab is through a dedicated testing facility and to build efficient and effective simulation-based acquisition supporting environment. In this paper, the ship / submarines C2 operations virtual simulator was developed to support the concept of Battle operations of naval combat experiments in training and tactical development. The ship C2 operations virtual simulator makes the anti-ship and anti-aircraft the engagement scenario for performed experiments using the SADM. The submarines C2 operations virtual simulator makes the anti-submarine engagement scenario for performed experiments using EAS. EAS System was created before reuse. EAS system by modifying the additional interfaces HLA-RTI has been reused. Reflected in the tactics and training after analysis of the results through the battle experiment. Also increase training fidelity through operator involvement. The anti-ship and anti-aircraft system architecture (SADM) and anti-submarine system architecture (EAS) requires unique design of system framework since two separate architectures should be integrated into a system. An C2 virtual linked architecture was used to integrate different system architecture. A C2 virtual linked software framework, designed that have integrated protocol for battle experimental linkage and battlefield visualization environment.

Enhanced WMAN System based on Region and Time Partitioning D-TDD OFDM Architecture (영역/시간 세분화 D-TDD OFDM 구조에 기반한 새로운 WMAN 시스템 구조 설계)

  • Kim, Mee-Ran;Cheong, Hee-Jeong;Kim, Nak-Myeong
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.43 no.11 s.353
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    • pp.68-77
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    • 2006
  • In accommodating the asymmetric traffic for future wireless multimedia services, the dynamic time division duplexing (D-TDD) scheme is considered as one of the key solutions. With the D-TDD mode, however, the inter-BS and inter-MS interference is inevitable during the cross time slot (CTS) period, and this interference seriously degrades the system performance. To mitigate such interference, we propose a region and time partitioning D-TDD architecture for OFDM systems. Each time slot in the CTS period is split into several minislots, and then each cell is divided into as many regions as the number of minislots per time slot. We then assign the minislots only to the users in its predefined corresponding region. On top of such architecture which inherently separates the interfering entities farther from each other, we design a robust time slot allocation scheme so that the inter-cell interference can be minimized. By the computer simulation, it has been verified that the proposed scheme outperforms the conventional time slot allocation methods in both the outage probability and the bandwidth efficiency.