• 한국가시화정보학회지
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• 제3권2호
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• pp.71-78
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• 2005

Uncertainty introduced by a cross-correlation algorithm based on FFT has been investigated using PIV standard images. The standard images were generated by the Monte Carlo simulation method. Both bias and random errors from the velocity vector have been analyzed with regard to the particle diameter, displacement, and the number of particles. The uncertainty of velocity is evaluated based upon the IS0/IEC standard. As a result, a total error of $0.26\%$ is included in the PIV cross-correlation algorithm. In addition, the uncertainty budget is presented, where the effect of the above three variables is examined. According to the budget, the variation of the number of particles within the interrogation window mainly contributes to the combined standard uncertainty of the real measured velocity field when excluding the effect of errors by the experiments itself. Finally, the expanded uncertainty is found to be about $12\%$ at the $95\%$ confidence level.

• 한국멀티미디어학회논문지
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• 제8권7호
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• pp.1000-1011
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• 2005

본 논문에서는 통계에 대한 지식이 부족한 임상 의학자들이 보다 쉽고 정확하게 데이터를 분석할 수 있도록 표본 데이터의 분포에 따라 적절한 분석 방법을 제시해주고, 분석 과정을 아이콘들의 트리로 구성한 가이드맵을 제공하는 의료 통계분석 시스템을 개발하였다. 개 발 시스템은 일반적으로 활용되는 통계 방법, 반복측정자료에 활용되는 통계 방법, 생존분석 등 의료 분야에서 자주 사용되는 분석법들을 포함하고 있다. 또한 3차원 글리프를 이용하여 결과를 인터랙티브하게 보여주고, 불확실성을 시각화함으로써 분석된 결과를 더욱 쉽게 이해할 수 있도록 하였다.

• 한국가시화정보학회지
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• 제4권2호
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• pp.37-43
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• 2006

An experimental apparatus for PIV performance evaluation has been developed. Stardard uncertainty of a two-dimensional cross-correlation PIV system was investigated based upon the standard experimental apparatus, which was devised to model the rigid body rotating flows. For the systematic analysis of the uncertainty introduced by each component (algorithm, CCD camera, frame grabber) of the PIV system, standard images are fed into the component independently. The standard experiments show that 53% of the uncertainty in the present PIV system results from the frame grabber but the errors from the algorithm and digital camera are ignorable.

• 한국가시화정보학회지
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• 제17권2호
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• pp.48-57
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• 2019

A straightforward strategy for particle image velocimetry (PIV) interrogation and post-processing has been proposed, aiming at reducing errors and clarifying vortex structures. The interrogation window size should be kept small to reduce bias error and improve spatial resolution. A spatial filter is then applied to the velocity field to reduce random error and clarify flow structure. The performance of three popular spatial filters were assessed: box filter, median filter, and local quadratic polynomial regression filter. In order to quantify random uncertainty, the image matching (IM) method is applied to an experimental dataset of homogeneous and isotropic turbulence (HIT) obtained by 2D-PIV. We statistically analyze the uncertainty propagation through the spatial filters, and verify the reduction in random uncertainty. Moreover, we illustrate that the spatial filters help clarify vortex structures using vortex identification criteria. As a result, PIV random uncertainty was reduced and the vortex structures became clearer by spatial filtering.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 춘계학술대회논문집
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• pp.1197-1202
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• 2001

Near-field acoustic holography is a powerful tool to visualize sound sources. This method requires pressure measurement at many points for a good hologram. Thus one has to measure carefully so that errors due to the uncertainty of position, sensor mismatch, and so on are reduced. A method to solve this problem is to use a well-designed measurement system. This paper introduces a sound visualization system at center for noise and vibration control (NOVIC), KAIST, and addresses the advantages in terms of the error reduction. The system consists of array microphones, array jigs, a system to control the position and the velocity of the jigs, a data acquisition system, and a monitoring system. This paper also shows some sound visualization results when the system is applied to a speaker and a computer. The results verifies that the sound visualization system is useful for identifying sound sources.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권2호
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• pp.749-766
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• 2021

Cyber powers around the world are conducting cyber information-gathering activities in cyberspace, a global domain within the Internet-based information environment. Accordingly, it is imperative to obtain the latest information through the cyber intelligence preparation of the battlefield (IPB) process to prepare for future cyber operations. Research utilizing the cyber battlefield visualization method for effective cyber IPB and situation awareness aims to minimize uncertainty in the cyber battlefield and enable command control and determination by commanders. This paper designed architecture by classifying cyberspace into a physical, logical network layer and cyber persona layer to visualize the cyber battlefield using BGP archive data, which is comprised of BGP connection information data of routers around the world. To implement the architecture, BGP archive data was analyzed and pre-processed, and cyberspace was implemented in the form of a Di-Graph. Information products that can be obtained through visualization were classified for each layer of the cyberspace, and a visualization method was proposed for performing cyber IPB. Through this, we analyzed actual North Korea's BGP and OSINT data to implement North Korea's cyber battlefield centered on the Internet network in the form of a prototype. In the future, we will implement a prototype architecture based on Elastic Stack.

• 한국가시화정보학회지
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• 제9권1호
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• pp.36-41
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• 2011

It is highly needed to measure the dissolved oxygen (DO) concentration field in water for a variety of purposes such as biological, industrial, environmental monitoring and medical application. Application of PSP (Pressure Sensitive Paint) which is sensitive to oxygen concentration has been carried out to measure DO concentration field using PtOEP/PS film and intensity based method under the UV-LEDs illumination. A micro round water jet having 100% of DO was obliquely impinged on to a PtOEP/PS film coated plate placed in a 0% of DO water container. DO concentration fields on the impinging plate were quantitatively visualized with a $2.94\;{\mu}m$ of spatial resolution. Through pixel-by-pixel calibration, uncertainty of each pixel by different sensitivity, different dye concentration and non-uniformity of illumination was removed. It is demonstrated that the high DO concentration region was coincided with the impingement area. The DO concentration gradient due to DO diffusion was affected by Reynolds number.

• 지질공학
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• 제12권2호
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• pp.179-188
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• 2002

최근 컴퓨터 성능 및 컴퓨터 가시화 기술의 발달에 힘입어 지반공학 분야의 지반조사결과를 가시화 할 수 있는 소프트웨어들이 출시되고 있다. 지반조사의 중요한 목적 중 하나는 건설대상 부지 내에 분포하는 건설에 불리하게 작용하는 불확실성을 예측하고 파악하는 것이다. 이들 불확실성은 시공의 안정성을 떨어뜨릴 뿐만 아니라 공기를 지연시키고 공사비를 증가시킨다. 3차원 가시화 기법은 이러한 지반의 불확실성을 극복할 수 있는 좋은 도구중 하나이다. 본 논문에서는 터널설계 및 시공분야에 3차원 가시화 기술, GIS 기술, 데이터베이스 기술을 적용하기위하여 새롭게 개발된 시스템을 소개한다. 가상현실과 3차원 가시화 기술은 지반구조 및 특성을 3차원 모델화 하는데 사용되었으며, 데이터베이스 기술과 GIS 기술을 접목하여 지반조사와 터널시공 중에 획득되는 지반정보를 데이트베이스화 하였다. 본 시스템을 이용함으로서 초목 엔지니어는 설계단계에서 계획을 세울 때 지반조사 정보를 유용하게 이용할 수 있고, 시공단계에서 공사의 안정성 및 경제성을 극대화시킬 있을 것이다.

• 한국가시화정보학회지
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• 제20권2호
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• pp.86-92
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• 2022

Pipe failure due to thermal fatigue and environmental regulations are increasing the importance of pipe monitoring systems in industrial plants. Since most pipe monitoring systems are focus on external crack inspected, it is necessary to temperature and concentration measuring monitoring system inside the pipe. These systems have spatial uncertainty due to sample inspection by one-point measurement. In addition, real-time measurement is not possible due to the limitation of time delay due to contact measurement. In this study, CT-TDLAS (Computed tomography-Tunable diode laser absorption spectroscopy) apply to overcome the limitations of existing methods. Lasers exhibiting an absorption response at a wavelength of 1395 nm were arranged in a lattice pattern on measuring cell. It showed that the inside of the pipe changed to an unstable combustion state over time.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2020년도 학술발표회
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• pp.171-171
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• 2020

Decision making strategies should consider both adaptiveness and robustness in order to deal with two main characteristics of climate change: non-stationarity and deep uncertainty. Especially, robust strategies are different from traditional optimal strategies in the sense that they are satisfactory over a wider range of uncertainty and may act as a key when confronting climate change. In this study, a new framework named Robust Stochastic Dynamic Programming (R-SDP) is proposed, which couples previously developed robust optimization (RO) into the objective function and constraint of SDP. Two main approaches of RO, feasibility robustness and solution robustness, are considered in the optimization algorithm and consequently, three models to be tested are developed: conventional-SDP (CSDP), R-SDP-Feasibility (RSDP-F), and R-SDP-Solution (RSDP-S). The developed models were used to derive optimal monthly release rules in a single reservoir, and multiple simulations of the derived monthly policy under inflow scenarios with varying mean and standard deviations are undergone. Simulation results were then evaluated with a wide range of evaluation metrics from reliability, resiliency, vulnerability to additional robustness measures. Evaluation results were finally visualized with advanced visualization tools that are used in multi-objective robust decision making (MORDM) framework. As a result, RSDP-F and RSDP-S models yielded more risk averse, or conservative, results than the CSDP model, and a trade-off relationship between traditional and robustness metrics was discovered.