• 한국측량학회지
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• 제25권6_1호
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• pp.507-516
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• 2007

Segmentation and organization of the LiDAR (Light Detection and Ranging) data of the Earth's surface are difficult tasks because the captured LiDAR data are composed of irregularly distributed point clouds with lack of semantic information. The reason for this difficulty in processing LiDAR data is that the data provide huge amount of the spatial coordinates without topological and/or relational information among the points. This study introduces LiDAR data segmentation technique by utilizing histograms of the LiDAR height image data and analyzing roof shape for 3D reconstruction and visualization of the buildings. One of the advantages in utilizing LiDAR height image data is no registration required because the LiDAR data are geo-referenced and ortho-projected data. In consequence, measurements on the image provide absolute reference coordinates. The LiDAR image allows measurement of the initial building boundaries to estimate locations of the side walls and to form the planar surfaces which represent approximate building footprints. LiDAR points close to each side wall were grouped together then the least-square planar surface fitting with the segmented point clouds was performed to determine precise location of each wall of an building. Finally, roof shape analysis was performed by accumulated slopes along the profiles of the roof top. However, simulated LiDAR data were used for analyzing roof shape because buildings with various shapes of the roof do not exist in the test area. The proposed approach has been tested on the heavily built-up urban residential area. 3D digital vector map produced by digitizing complied aerial photographs was used to evaluate accuracy of the results. Experimental results show efficiency of the proposed methodology for 3D building reconstruction and large scale digital mapping especially for the urban area.

• Structural Engineering and Mechanics
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• 제22권2호
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• pp.197-222
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• 2006

In this paper, the non-linear time-dependent closed-form, discrete and combined solutions for the post-elastic response of a geometrically and physically non-linear suspended cable to a uniformly distributed load considering the creep effects, are presented. The time-dependent closed-form method for the particularly straightforward determination of a vertical uniformly distributed load applied over the entire span of a cable and the accompanying deflection at time t corresponding to the elastic limit and/or to the elastic region, post-elastic and failure range of a suspended cable is described. The actual stress-strain properties of steel cables as well as creep of cables and their rheological characteristics are considered. In this solution, applying the Irvine's theory, the direct use of experimental data, such as the actual stress-strain and strain-time properties of high-strength steel cables, is implemented. The results obtained by the closed-form solution, i.e., a load corresponding to the elastic limit, post-elastic and failure range at time t, enable the direct use in the discrete non-linear time-dependent post-elastic analysis of a suspended cable. This initial value of load is necessary for the non-linear time-dependent elastic and post-elastic discrete analysis, concerning incremental and iterative solution strategies with tangent modulus concept. At each time step, the suspended cable is analyzed under the applied load and imposed deformations originated due to creep. This combined time-dependent approach, based on the closed-form solution and on the FEM, allows a prediction of the required load that occurs in the post-elastic region. The application of the described methods and derived equations is illustrated by numerical examples.

• 한국지반환경공학회 논문집
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• 제19권9호
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• pp.13-19
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• 2018

최근 우리나라는 도시의 노후화가 가속되며 사회기반시설에 대한 다양한 문제점들이 발생하고 있다. 이에 영향을 받는 도시철도 구조물 또한 노후화가 가속되면서 시민들의 불안감은 커지고 있어 이에 대한 연구의 필요성이 제기되고 있다. 도시철도 구조물은 시민의 안전과 밀접하게 연관되어 있어 이상 현상을 신속히 발견하여 처리해야 한다. 도시철도 지하구조물의 경우, 선로에 변형률 게이지를 부착하거나 광섬유 센서인 브래그 격자 센서를 활용하여 측정하고 있다. 그러나 이러한 방식은 장거리 모니터링에는 용이하지만 공간 분해능이 떨어져 이상구간을 정밀하게 측정하는 데에는 한계가 있다. 따라서 본 연구에서는 브릴루앙 광 상관영역 기반(Brillouin Optical Correlation Domain Analysis; BOCDA)의 분포형 광섬유 센서 시스템을 구축하여 도시철도 지하구조물인 궤도에 관한 모니터링 적용성 평가를 수행하였다. 구축된 BOCDA 기반의 고분해능 분포형 광섬유 센서 시스템은 공간분해능 10, 20, 50, 100cm이며 측정거리 2km 구간에 대해 상시 모니터링 및 특정 위치에 대해 모니터링이 가능하다. 철도 폐선부지에 광섬유를 약 250m 포설하여 상시 모니터링에 대한 적용성을 평가하였으며, 윤중 시험기를 사용하여 특정위치에 대한 모니터링 적용성을 평가하였다. 시험결과, 공간분해능 1.0m에서 0.1m로 낮아질수록 손실이 커지는 경향을 보이고 있으며, 공간분해능이 낮을수록 측정 속도는 감소하지만 위치 및 변형에 대한 정확한 데이터를 얻을 수 있었다. 추후, 포설방법이 해결된다면 다양한 구조물의 모니터링에 활용될 수 있을 것이다.

• The Journal of Asian Finance, Economics and Business
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• 제7권8호
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• pp.323-332
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• 2020

This study aims to examine the level of students' satisfaction toward the services (i.e. accommodation facilities, transportation facilities, and recreation and sports facilities) provided by the public universities in Bangladesh. The study also aims to identify the major service factors that influence students' satisfaction in public universities in the country. A cross-sectional survey was conducted at six public universities to obtain primary data. A standardized questionnaire was distributed to a total of 500 randomly selected students to collect the data. Several statistical tools, namely, reliability analysis, descriptive statistics, correlation analysis and multiple regression analysis were employed to analyze the data. The findings revealed that recreation and sports facilities have the strongest impact on students' satisfaction in the public universities in Bangladesh. Transportation facilities also have positive and significant impact on student's satisfaction. However, the study found a negative correlation between accommodation facilities and students' satisfaction indicating that students are not satisfied with the accommodation facilities provided by the public universities. The findings of this study provide an insight about students' satisfaction that might be useful to authorities of the public universities and other higher educational institutions in designing policies for various services and facilities to be provided to their students.

• Journal of Electrical Engineering and Technology
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• 제13권3호
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• pp.1110-1122
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• 2018

This paper proposes an alternative method to evaluate the effect of wind power to the power system stability with small disturbance. Alternatively, available techniques for stability analysis of a power system based on deterministic methods are less accurate for high penetration of wind power. Numerical simulations of random behaviors are computationally expensive. A stochastic stability index (SSI) is proposed for the power system stability evaluation based on the theory of stochastic stability and energy function, specifically the stochastic derivative of the relative well-defined energy function and the critical energy. The SSI is implemented on the modified nine-bus system including wind turbines under different conditions. A doubly-fed induction generator (DFIG) wind turbine is characterized and modeled using measured wind data from several sites in Thailand. Each of the obtained wind power data is analyzed. The wind power effect is modeled considering the aggregated effect of wind turbines. With the proposed method, the system behavior is properly predicted and the stability is quantitatively evaluated with less computational effort compared with conventional numerical simulation methods.

• 한국인쇄학회지
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• 제30권2호
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• pp.13-22
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• 2012

This research attempts to analyze communication effects of print ad having pictorial typography. 150 Questionnaires were distributed to respondents staying Daejeun City and 148 copies were retreated for five days from April 22nd to 26th, 2012. Frequency analysis, factor analysis, Cronbach's alpha for reliability analysis were utilized for data analysis with SPSS 12.0. For testing hypothesis, regression analysis was used. As result of testing hypothesis, 'informative, beneficial, creative, reliable' were partially significant to attitude towards print ad having pictorial typography. That means 'creative' and 'reliable' were insignificant, while 'informative' and 'beneficial' are significant. Variable of the most influencing on attitude towards advertising is 'informative.' 'Informative, beneficial, creative, and reliable' were partially significant to brand attitude, too. That means 'beneficial' and 'creative' were insignificant, while 'informative' and 'reliable' were significant. Variable of the most influencing on brand attitude was 'reliable.' Therefore, to enhance communication effect of print ad having pictorial typography, 'informative' and 'reliable' are most significant variables.

• 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.

• 한국인터넷방송통신학회논문지
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• 제18권6호
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• pp.1-9
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• 2018

현재 이슈가 되고 있는 4차 산업혁명에서 다양한 빅데이터 기술들을 통하여 기존의 느린 속도 보다 빠른 분석 결과를 즉각적으로 받아 볼 수 있고, 모바일과 웹에서 실시간 모니터링을 하는 연구를 진행하였다. 먼저 IoT 기기인 Raspberry Pi를 이용하여 다양한 비정형 센서 데이터를 생성하고 센서 데이터를 실시간 수집하고, 수집한 데이터를 여러 개의 노드를 이용해 분산 저장한 뒤 저장된 센서 데이터를 가공, 정제 처리하여 분석 모델 및 알고리즘을 통해 분석 결과를 시각화하여 출력한다. 이러한 방법들을 이용한 진행은 IoT를 이용한 빅데이터 및 모바일 관련 분야에서 필요한 고급 인력을 양성 및 데이터를 효율적이고 빠르게 처리할 수 있다. 또한, 실시간 모니터링을 통하여 연구결과의 신뢰성을 확인할 수 있는 정보를 제공하고자 한다.

• 지질공학
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• 제30권3호
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• pp.253-268
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• 2020

본 연구에서는 분포형 수문모형 SWAT-K를 사용한 함양률을 산정하고 이를 뒷받침하기 위해 유역 내에서 실제로 관측한 수문곡선 자료를 기반으로 기저유출 분리법을 이용하여 함양량 산정의 타당성을 평가하였다. 통상 지하수 개발가능량 산정 시 10년 빈도 갈수 시 강수량에 평균함양률을 곱하여 실무에 활용하고 있으나, 실제로 함양률은 강수량이 작을수록 작아지는 경향을 보이기 때문에 평균 함양률을 사용하게 되면 개발가능량이 과다 산정될 가능성이 높다. 이러한 문제를 해결하기 위해서 본 연구에서는 강수량 규모를 고려한 함양량으로 함양률을 재산정하여 개발가능량을 산정하였다. 이 방법을 의왕·과천·성남시에 적용한 결과 소유역별 개발가능량은 기존 방법 대비 55.5~77.6%로 감소하는 것으로 나타났다.

• 한국태양에너지학회 논문집
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• 제38권4호
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• pp.55-66
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• 2018

nZEH (net-Zero Energy House) is defined as a self-sufficient energy building where the sum of energy output generated from new & renewable energy system and annual energy consumption is zero. The electricity generated by new & renewable energy system with the form of distributed generation is preferentially supplied to electrical demand, and surplus electricity is transmitted back to grid. Due to the recent expansion of houses with photovoltaic system and the nZEH mandatory by 2025, the rapid increase of distributed generation is expected. Which means, we must prepare for an electricity-power accident and stable electricity supply. Also electricity charges have to be reduce and the grid-connected should be operated efficiently. The introduction of ESS is suggested as a solution, so the analysis of the load matching and grid interaction is required to optimize ESS design. This study analyzed the load matching and grid interaction by expected consumption behavior using actual data measured in one-minute intervals. The experiment was conducted in three nZEH with photovoltaic system, called all-electric houses. LCF (Load Cover Factor), SCF (Supply Cover Factor) and $f_{grid}$ (Grid Interaction Index) were evaluated as an analysis indicator. As a result, LCF, SCF and $f_{grid}$ of A house were 0.25, 0.23 and 0.27 respectively; That of B house were 0.23, 0.23, 0.19, and that of C were 0.20, 0.19, 0.27 respectively.