• 한국산학기술학회논문지
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• 제21권3호
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• pp.414-419
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• 2020

본 연구에서는 사장교의 케이블 가속도계로부터 확보한 방대한 계측데이터의 활용을 확대하고자 인공지능 기반의 케이블 장력 추정 모델을 개발하였다. 케이블 장력 추정 모델은 진동법에 따른 장력 추정 과정에서 고유진동수를 판정할 수 있는 알고리즘을 핵심으로 하며 학습데이터 구성에 적합하고 판정 결과에 대한 성능이 확보될 수 있도록 입력층, 은닉층, 출력층으로 구성되는 인공신경망(Artificial Neural Network)을 적용하였다. 인공신경망의 학습데이터는 케이블 가속도 계측데이터를 진동수로 변환 후 구성하였으며 고유진동수를 중심으로 일정한 패턴을 갖는 특성을 활용하여 기계학습을 진행하였다. 학습데이터 구성 시 다수 패턴의 고유진동수를 대표할 수 있도록 다양한 크기의 진폭을 갖는 진동수를 사용하고 일정 수준으로 진동수를 누적하여 사용할 경우 고유진동수에 대한 판정 성능이 개선됨을 확인하였다. 장력 추정 모델의 성능을 판단하기 위해 계측분석 기술자에 의해 추정한 장력의 관리기준과 비교하였다. 케이블 가속도계로부터 확보한 139개의 진동수를 입력값으로 사용하여 검증을 수행한 결과 실제 정답과 유사하게 고유진동수를 판정하였고 고유진동수에 의해 케이블의 장력을 추정한 결과는 96.4%의 수준으로 관리기준에 부합하는 결과를 보여주고 있다.

• Steel and Composite Structures
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• 제15권1호
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• pp.103-130
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• 2013

Fire performance and fire safety of high-rise buildings have become major concerns after the disasters of World Trade Center in the U.S. in 2001 and Windsor tower in Spain in 2005. Performance based design (PBD) approaches have been considered as a better method for fire resistance design of structures because it is capable of incorporating test results of most recent fire resistance technologies. However, there is a difficulty to evaluate fireproof performance of large structures, which have multiple structural members such as columns, slabs, and walls. The difficulty is mainly due to the limitation in the testing equipment, such as size of furnace that can be used to carry out fire tests with existing criteria like ISO 834, BS 476, and KS F 2257. In the present research, a large scale calorie meter (10 MW) was used to conduct three full scale fire tests on medical modular blocks. Average fire load of 13.99 $kg/m^2$ was used in the first test. In the second test, the weighting coefficient of 3.5 (the fire load of 50 $kg/m^2$) was used to simulate the worst fire scenario. The flashover of the medical modular block occurred at 62 minutes in the first test and 12 minutes in the second test. The heat resistance capacity of the external wall, the temperatures and deformations of the structural members satisfied the requirements of fire resistance performance of 90 minutes burning period. The total heat loads and the heat values for each test are calculated by theoretical equations. The duration of burning was predicted. The predicted results were compared with the test results, and they agree quite well.

• 품질경영학회지
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• 제50권4호
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• pp.811-830
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• 2022

Purpose: In this paper, we will discuss 1) prioritizing databases to be integrated; 2) which data elements should be emphasized in federated database integration; and 3) the degree of efficiency in the integration. This paper aims to lay the groundwork for building data governance by presenting guidelines for database integration using metrics to identify and evaluate the capabilities of the UK's air quality databases. Methods: This paper intends to perform relative efficiency analysis using Data Envelope Analysis among the multi-criteria decision-making methods. In federated database integration, it is important to identify databases with high integration efficiency when prioritizing databases to be integrated. Results: The outcome of this paper aims not to present performance indicators for the implementation and evaluation of data governance, but rather to discuss what criteria should be used when performing 'federated integration'. Using Data Envelope Analysis in the process of implementing intelligent data governance, authors will establish and present practical strategies to discover databases with high integration efficiency. Conclusion: Through this study, it was possible to establish internal guidelines from an integrated point of view of data governance. The flexiblity of the federated database integration under the practice of the data governance, makes it possible to integrate databases quickly, easily, and effectively. By utilizing the guidelines presented in this study, authors anticipate that the process of integrating multiple databases, including the air quality databases, will evolve into the intelligent data governance based on the federated database integration when establishing the data governance practice in the railway industry.

• 한국수자원학회논문집
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• 제44권12호
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• pp.1015-1029
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• 2011

전통적인 다기준의사결정(Multi-Criteria Decision Analysis, MCDA)기법은 복수 대안을 평가기준과 의사결정권자의 선호도에 따라 평가하여 유역 전반에 걸친 최적 대안을 선정하는 데 있어 효율적으로 사용되는 기법이다. 하지만, 홍수터 관리를 위한 유역 전반에 걸친 의사결정 정보는 지역적 특색을 반영할 수 있는 공간적 변동성을 체계적으로 파악할 수 있는 능력에 제한을 받고 있다. 이와 관련하여 최적대안 결정시 지리정보체계(GIS)의 적용은 신속하고 정확한 정보를 제공하고, 공간적인 차원에서 야기되는 문제의 해결과 합리적인 자원의 이용 및 배분 등을 수행하여 해당 기술 분야의 전문가들과 최종의사결정권자들의 의사결정과정에서 요구되는 각종 정보를 공간분포형태로 제시할 수 있어 상충하는 여러 목표 간의 갈등을 최소화하고, 투명하고 객관적인 의사결정을 수행할 수 있도록 도와준다. 본 연구에서는 홍수터 해석 분야에서 GIS와 MCDA 기법을 결합(공간형 MCDA기법)하여 홍수피해 저감대책 평가를 수행하였다. 수자원 분야의 고전적인 MCDA기법인 CP (Compromise Programming)와 SCP (Spatial Compromising Programming)기법 적용을 위해 부산 수영강 유역에 대한 사례연구를 통하여 적용성을 평가한 결과 CP기법은 해당 유역에 대해 단일 홍수피해 저감대책만을 제시하는 문제점이 있었으며 GIS와 결합된 SCP기법은 모든 격자지점의 공간특성 반영이 가능하여 관심 지점에 대한 개별 대안을 의사결정권자들에게 제시할 수 있었다.

• KEPCO Journal on Electric Power and Energy
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• 제8권2호
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• pp.159-179
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• 2022

Often a network becomes complex, and multiple entities would get in charge of managing part of the whole network. An example is a utility grid. While the entire grid would go under a single utility company's responsibility, the network is often split into multiple subsections. Subsequently, each subsection would be given as the responsibility area to the corresponding sub-organization in the utility company. The issue of how to make subsystems of adequate size and minimum number of interconnections between subsystems becomes more critical, especially in real-time simulations. Because the computation capability limit of a single computation unit, regardless of whether it is a high-speed conventional CPU core or an FPGA computational engine, it comes with a maximum limit that can be completed within a given amount of execution time. The issue becomes worsened in real time simulation, in which the computation needs to be in precise synchronization with the real-world clock. When the subject of the computation allows for a longer execution time, i.e., a larger time step size, a larger portion of the network can be put on a computation unit. This translates into a larger margin of the difference between the worst and the best. In other words, even though the worst (or the largest) computational burden is orders of magnitude larger than the best (or the smallest) computational burden, all the necessary computation can still be completed within the given amount of time. However, the requirement of real-time makes the margin much smaller. In other words, the difference between the worst and the best should be as small as possible in order to ensure the even distribution of the computational load. Besides, data exchange/communication is essential in parallel computation, affecting the overall performance. However, the exchange of data takes time. Therefore, the corresponding consideration needs to be with the computational load distribution among multiple calculation units. If it turns out in a satisfactory way, such distribution will raise the possibility of completing the necessary computation in a given amount of time, which might come down in the level of microsecond order. This paper presents an effective way to split a given electrical network, according to multiple criteria, for the purpose of distributing the entire computational load into a set of even (or close to even) sized computational loads. Based on the proposed system splitting method, heavy computation burdens of large-scale electrical networks can be distributed to multiple calculation units, such as an RTDS real time simulator, achieving either more efficient usage of the calculation units, a reduction of the necessary size of the simulation time step, or both.

• 대한산업공학회지
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• 제40권6호
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• pp.628-641
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• 2014

Stepwise efficiency improvement in data envelopment analysis (DEA)-based benchmarking is a realistic and effective method by which inefficient decision making units (DMUs) can choose benchmarks in a stepwise manner and, thereby, effect gradual performance improvement. Most of the previous research relevant to stepwise efficiency improvement has focused primarily on how to stratify DMUs into multiple layers and how to select immediate benchmark targets in leading levels for lagging-level DMUs. It can be said that the sequence of benchmark targets was constructed in a myopic way, which can limit its effectiveness. To address this issue, this paper proposes an optimization approach to the construction of a sequence of benchmarks in DEA-based benchmarking, wherein two optimization criteria are employed : similarity of input-output use patterns, and proximity of input-output use levels between DMUs. To illustrate the proposed method, we applied it to the benchmarking of 23 national universities in South Korea.

• Journal of the Korean Data and Information Science Society
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• 제27권2호
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• pp.275-284
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• 2016

정확한 전력수요 예측은 에너지 소비를 줄이고 전력수급의 불균형을 방지한다. 본 연구는 외부요인의 영향을 가장 적게 받는 특정 시간대의 일 단위 전력 수요량을 참조선 (reference line)으로 한 시계열모형을 세우고자 한다. 고려된 시계열모형은 슬라이딩 창을 이용한 이중 계절성 Holt-Winters 모형과 TBATS 모형이다. 시계열모형의 모수는 2009년 1월 4일부터 2011년 12월 31일까지 자료를 이용하여 추정되었으며, 2012년 1월 1일부터 2012년 12월 29일까지의 각 모형의 전력수요량을 예측하여 성능을 비교하였다. RMSE와 MAPE를 통해 예측 성능을 비교한 결과 TBATS 모형의 성능이 우수하였다.

• 한국작물학회지
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• 제41권6호
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• pp.656-664
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• 1996

광산, 진주와 밀양에서 수확된 사천006, 두산12 호와 두산2002 종자를 인위노화시켜 종자세를 조절하였다. 이들 종자로서 표준발아검사(standard germination test), 저온발아검사(cold germi-nation test), 전기전도도검사(electroconductivity test)와 Tetrazolium 검사(TZ vigor test)를 실시하여 포장출아율 및 수량과의 관계를 구명하고자 하였다. 9가지 seed lot을 이용한 맥주보리의 포장출아율 예측에는 표준발아검사에서의 발아율만으로 65%의 예측효과가 인정되었고 표준발아검사에서의 유묘세와 저온발아검사에서의 유묘세와 발아율 parameter 또한 효과적인 방법임을 다중회귀분석으로 알 수 있었다. 수량 예측에는 TZ검사에서의 종자세 지수와 표준발아검사에서의 발아율과 TZ검사에서의 예측발아율이 효과적 인 parameter임을 알 수 있었다.

• 대한산업공학회지
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• 제36권2호
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• pp.138-145
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• 2010

In this paper, we consider the information processing system, which organizes the collected data to meaningful information when the number of data collected from multiple sources reaches to a predetermined number, and performs any action by processing the collected data, or transmits to other devices or systems. We derive an analytical model to calculate the time until it takes to process information after starting to collect data. Therefore, in order to complete the processing data within certain time constraints, we develop some design criteria to control various parameters of the information processing system. Also, we analyze the discrete time model for packet switching networks considering data with no particular arrival nor drop pattern. We analyze the relationship between the number of required packets and average information processing time through numerical examples. By this, we show that the proposed model is able to design the system to be suitable for user's requirements being complementary the quality of information and the information processing time in the system with time constraints.

• 한국조경학회지
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• 제28권4호
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• pp.117-124
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• 2000

This paper presents a design of urban waterfront park using agricultural reservoir in urban fringe area to meet increasing leisure demand for urban resident and to improve resident's quality of life through preventing the reservoir from urban use after reclamation. The site, Unam-Ji, is located on northern part of Taegu metropolitan area, having 17,791 square meters. We had designed this park from 1997 to 1998. After analyzed such factor as accessibility, current land uses, topography, hydrology, vegetation and landscape, climate, and soil, we constructed basic design scheme and principes such as conservation of natural resources, meeting user's recreation demands, providing opportunities for experiencing natural process, integrating naturalness and amenity of the site, and comfortable place with natural dynamism. Based on these principles, we have designed Unam-Ji waterfront park having intrinsic characteristics of the site, maintaining water quality and ecological restoration and improving water-based recreation opportunities. After evaluation of such criteria of design alternative as land use and circulation, spatial organization, convenience for use of and maintenance, conservation of natural environment, and degree of achieving planning and design goals, and maintaining landscape, we have visualized and formalized waterfront park in design process, which is consisted of four squares-- green square for multiple uses, water-based recreation square, pedestrian roads and decks near waterfront, performance square and fords near waterfront. In conclusion, this waterfront park design contributes to improve quality of urban development through preserving agricultural as an important component of urban water system and provide important planning and design implications in urban open space planning.