• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.1516-1519
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• 1997

With disseminationof Distributed Control Systems(DCS), the huge amounts of process operation data could have been available and led to figure out process behaviors better on the statistical basis. Until now, the statistical modeling technology has been susally applied to process monitoring and fault diagnosis. however, it has been also thought that these process information, extracted from statistical analysis, might serve a great opportunity for process operation improvements and process improvements. This paper proposed a general methodolgy for process operation improvements including data analysis, backing up the result of analysis based on the methodology, and the mapping physical physical phenomena to the Principal Components(PC) which is the most distinguished feature in the methodology form traditional statistical analyses. The application of the proposed methodology to the Balst Furnace(BF) process has been presented for details. The BF process is one of the complicated processes, due to the highly nonlinear and correlated behaviors, and so the analysis for the process based on the mathematical modeling has been very difficult. So the statisitical analysis has come forward as a alternative way for the useful analysis. Using the proposed methodology, we could interpret the complicated process, the BF, better than any other mathematical methods and find the direction for process operation improvement. The direction of process operationimprovement, in the BF case, is to increase the fludization and the permeability, while decreasing the effect of tapping operation. These guide directions, with those physical meanings, could save fuel cost and process operator's pressure for proper actions, the better set point changes, in addition to the assistance with the better knowledge of the process. Open to set point change, the BF has a variety of steady state modes. In usual almost chemical processes are under the same situation with the BF in the point of multimode steady states. The proposed methodology focused on the application to the multimode steady state process such as the BF, consequently can be applied to any chemical processes set point changing whether operator intervened or not.

• Smart Structures and Systems
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• 제25권2호
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• pp.135-153
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• 2020

There has been a sustained interest towards the non-contact structural displacement measurement by means of videogrammetric technique. On the way forward, one of the major concerns is the spurious image drift induced by temperature variation. This study therefore carries out an investigation into the temperature effect of videogrammetric technique, focusing on the exploration of the mechanism behind the temperature effect and the elimination of the temperature-caused measurement error. 2D videogrammetric measurement tests under monotonic or cyclic temperature variation are first performed. Features of measurement error and the casual relationship between temperature variation and measurement error are then studied. The variation of the temperature of digital camera is identified as the main cause of measurement error. An excellent linear relationship between them is revealed. After that, camera parameters are extracted from the mapping between world coordinates and pixels coordinates of the calibration targets. The coordinates of principle point and focal lengths show variations well correlated with temperature variation. The measurement error is thought to be an outcome mainly attributed to the variation of the coordinates of principle point. An approach for eliminating temperature-caused measurement error is finally proposed. Correlation models between camera parameters and temperature are formulated. Thereby, camera parameters under different temperature conditions can be predicted and the camera projective matrix can be updated accordingly. By reconstructing the world coordinates with the updated camera projective matrix, the temperature-caused measurement error is eliminated. A satisfactory performance has been achieved by the proposed approach in eliminating the temperature-caused measurement error.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2009년 추계학술대회논문집
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• pp.151-158
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• 2009

To implement the insects' flapping flight for developing flapping MAVs(micro air vehicles), the unsteady flow characteristics of the insects' forward flight is investigated. In this paper, two-dimensional FSI(Fluid-Structure Interaction) simulations are conducted to examine realistic flow features of insects' flapping flight and to examine the flexibility effects of the insect's wing. The unsteady incompressible Navier-Stokes equations with an artificial compressibility method are implemented as the fluid module while the dynamic finite element equations using a direct integration method are employed as the solid module. In order to exchange physical information to each module, the common refinement method is employed as the data transfer method. Also, a simple and efficient dynamic grid deformation technique based on Delaunay graph mapping is used to deform computational grids. Compared to the earlier researches of two-dimensional rigid wing simulations, key physical phenomena and flow patterns such as vortex pairing and vortex staying can still be observed. For example, lift is mainly generated during downstroke motion by high effective angle of attack caused by translation and lagging motion. A large amount of thrust is generated abruptly at the end of upstroke motion. However, the quantitative aspect of flow field is somewhat different. A flexible wing generates more thrust but less lift than a rigid wing. This is because the net force acting on wing surface is split into two directions due to structural flexibility. As a consequence, thrust and propulsive efficiency was enhanced considerably compared to a rigid wing. From these numerical simulations, it is seen that the wing flexibility yields a significant impact on aerodynamic characteristics.

• 방송공학회논문지
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• 제16권4호
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• pp.596-601
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• 2011

양안식 3차원 방송의 경우 좌우 두 시점에 해당하는 영상을 동시에 전송해야 하기 때문에 전송 대역폭의 부담이 매우 크다. 이러한 부담을 줄이기 위해 좌우 시점의 두 영상을 전송하는 대신에 좌영상과 이에 해당하는 깊이맵을 부호화하여 전송하는 방법이 있다. 이러한 3차원 방송 시스템의 수신단에서는 좌영상과 깊이맵을 복호한 뒤에 우영상을 만들어 좌우 영상을 실시간으로 출력한다. 본 논문에서는 좌영상과 깊이맵을 이용하여 가상시점 영상을 생성할 때 생기는 빈 공간을 효율적으로 채우는 기법을 제안하고, 전 과정의 실시간 처리를 위해 이를 GPU상에서 병렬로 처리되도록 구현했다. 그 결과 효과적으로 홀 채움을 수행하면서 CPU 대비 15배 이상 빠르게 양안식 영상을 생성할 수 있었다.

• International Journal of Concrete Structures and Materials
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• 제7권3호
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• pp.225-238
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• 2013

In this study, a two-layer feed-forward neural network was constructed and applied to determine a mapping associating mix design and testing factors of cement-nano silica (NS)-rice husk ash ternary blended concrete samples with their performance in conductance to the water absorption properties. To generate data for the neural network model (NNM), a total of 174 field cores from 58 different mixes at three ages were tested in the laboratory for each of percentage, velocity and coefficient of water absorption and mix volumetric properties. The significant factors (six items) that affect the permeability properties of ternary blended concrete were identified by experimental studies which were: (1) percentage of cement; (2) content of rice husk ash; (3) percentage of 15 nm of $SiO_2$ particles; (4) content of NS particles with average size of 80 nm; (5) effect of curing medium and (6) curing time. The mentioned significant factors were then used to define the domain of a neural network which was trained based on the Levenberg-Marquardt back propagation algorithm using Matlab software. Excellent agreement was observed between simulation and laboratory data. It is believed that the novel developed NNM with three outputs will be a useful tool in the study of the permeability properties of ternary blended concrete and its maintenance.

• 시스템엔지니어링학술지
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• 제11권2호
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• pp.1-11
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• 2015

During the industrial plant system life cycle, required technologies are developed and assessed to analyze their performance, risks and costs. The assessment is called technology readiness assessment (TRA) and the measure of readiness is called technology readiness level (TRL). The TRL consists of 9 levels and through the TRL assessment, the technology to be developed and its components are assigned to their appropriate TRL. TRL assessment should be performed in each life cycle stages to monitor the technology readiness and analyze the potential risks and costs. However, even though the concept of TRL has been largely adopted by numerous organizations and industry, direct and clear assignment of target TRL for each life cycle stage has been overlooked. Direct mapping/assignment of target TRL for each life cycle has benefits as follow: (1) the technical risks condition of each life cycle stage can be better understood, (2) cost incurred if the technology development is failed can be analyzed in each life cycle stage, and (3) more effective decision making because the technology readiness achievement for each life cycle stages is agreed beforehand. In this paper, we propose a steel-making plant system life cycle and TRL assignment to each of the system life cycle stage. By directly assigning target TRL for each life cycle stages, we look forward to a more coordinated (in terms of exit criteria) and highly effective (in terms of technical risks identification and eventually prevent project failure) technology development and assessment processes.

• 한국정보통신학회논문지
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• 제21권5호
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• pp.861-868
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• 2017

도핑 되지 않은 반 절연 LEC GaAs내의 EL2와 얕은 준위 분포를 영상화하기 위해 대역단 적외선 영상 기법을 활용했다. 대역단 적외선 투사 매핑에 근거한 본 기법은 분석 속도가 빠르고 비파괴적인 방법이다. EL2 흡수 영상이 콘트라스트 반전되는 대역단 부근에 대한 정량적인 해석은 아직 보고되지 않고 있다. 본 논문은 대역단 부근에서 영상의 특정 부분(cell, wall)에 대한 포토퀀칭 메커니즘의 스펙트럼-, 공간- 및 온도- 종속성을 논하고 있다. 결함 부분별(EL2w, EL2b)로 포토퀀칭 개시점이 다른 것은 불순물 종류의 차이로 인한 서로 다른 전기적 작용에 기인한 것으로 해석할 수 있다. 전위(dislocation) 밀도가 높은 곳에서는 EL2b 밀도는 약간 적은 반면 EL2w 밀도는 보다 많다는 것을 정량적 해석으로부터 확인 했다.

• 지구물리와물리탐사
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• 제18권4호
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• pp.216-222
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• 2015

항공 전자 탐사법은 지하 천부의 전도성 광체 탐사를 위하여 이미 수십년 전에 도입되었다. 그러나 통상적인 시간 영역 항공 전자 탐사(ATEM) 시스템은 신호가 미약하여 가탐 심도에 한계가 있다. 최근 이러한 문제점을 극복하기 위하여 지상 송신원 시간 영역 항공 전자 탐사법(GREATEM)이 개발되었다. GREATEM은 지상에 설치된 긴 전선을 송신원으로 사용하는 준 항공 전자 탐사법이다. 항공 전자 탐사에서는 방대한 자료가 획득되므로, 계산 시간의 절감을 위하여 대개 1차원 해석 방법이 사용되고 있다. 그러나 GREATEM은 1차원 모델링의 경우에도 긴 전선을 따라 수치 적분이 필요하므로 루프 송신원을 사용하는 ATEM의 1차원 모델링에 비하여 계산 시간이 많이 걸린다는 문제점이 있다. 이 논문에서는 일반적인 1차원 모델링보다 비교할 수 없을 정도로 계산 속도가 빠른 ABFM법을 도입하여 ATEM 1차원 모델링을 수행하였다. 통상적인 모델링과 ABFM 결과를 비교한 결과, ABFM법은 GREATEM 1차원 모델링에도 적용 가능할 것으로 확인되었다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.1
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• pp.185-189
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• 2006

Time series analysis is a frequently effective method of constructing model and prediction in data processing of deformation monitoring. The monitoring data sample must to be as more as possible and time intervals are equal roughly so as to construct time series model accurately and achieve reliable prediction. But in the project practice of GPS deformation monitoring, the monitoring data sample can't be obtained too much and time intervals are not equal because of being restricted by all kinds of factors, and it contains many variates in the deformation model moreover. It is very important to study the data processing method for small samples and multi-variates time series in GPS deformation monitoring. A new method of establishing small samples and multi-variates deformation model and prediction model are put forward so as to resolve contradiction of small samples and multi-variates encountered in constructing deformation model and improve formerly data processing method of deformation monitoring. Based on the system theory, a deformation body is regarded as a whole organism; a time-dependence linear system model and a time-dependence bilinear system model are established. The dynamic parameters estimation is derived by means of prediction fit and least information distribution criteria. The final example demonstrates the validity and practice of this method.

• Toxicological Research
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• 제35권4호
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• pp.295-301
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• 2019

In this review, we describe the absorption rates (Caco-2 cell permeability) and hepatic/plasma pharmacokinetics of 53 diverse chemicals estimated by modeling virtual oral administration in rats. To ensure that a broad range of chemical structures is present among the selected substances, the properties described by 196 chemical descriptors in a chemoinformatics tool were calculated for 50,000 randomly selected molecules in the original chemical space. To allow visualization, the resulting chemical space was projected onto a two-dimensional plane using generative topographic mapping. The calculated absorbance rates of the chemicals based on cell permeability studies were found to be inversely correlated to the no-observed-effect levels for hepatoxicity after oral administration, as obtained from the Hazard Evaluation Support System Integrated Platform in Japan (r = -0.88, p < 0.01, n = 27). The maximum plasma concentrations and the areas under the concentration-time curves (AUC) of a varied selection of chemicals were estimated using two different methods: simple one-compartment models (i.e., high-throughput toxicokinetic models) and simplified physiologically based pharmacokinetic (PBPK) modeling consisting of chemical receptor (gut), metabolizing (liver), and central (main) compartments. The results obtained from the two methods were consistent. Although the maximum concentrations and AUC values of the 53 chemicals roughly correlated in the liver and plasma, inconsistencies were apparent between empirically measured concentrations and the PBPK-modeled levels. The lowest-observed-effect levels and the virtual hepatic AUC values obtained using PBPK models were inversely correlated (r = -0.78, p < 0.05, n = 7). The present simplified PBPK models could estimate the relationships between hepatic/plasma concentrations and oral doses of general chemicals using both forward and reverse dosimetry. These methods are therefore valuable for estimating hepatotoxicity.