• Structural Engineering and Mechanics
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• 제54권2호
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• pp.337-362
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• 2015

This paper presents a feasibility study on structural damage alarming and localization of long-span cable-supported bridges using multi-novelty indices formulated by monitoring-derived modal parameters. The proposed method which requires neither structural model nor damage model is applicable to structures of arbitrary complexity. With the intention to enhance the tolerance to measurement noise/uncertainty and the sensitivity to structural damage, an improved novelty index is formulated in terms of auto-associative neural networks (ANNs) where the output vector is designated to differ from the input vector while the training of the ANNs needs only the measured modal properties of the intact structure under in-service conditions. After validating the enhanced capability of the improved novelty index for structural damage alarming over the commonly configured novelty index, the performance of the improved novelty index for damage occurrence detection of large-scale bridges is examined through numerical simulation studies of the suspension Tsing Ma Bridge (TMB) and the cable-stayed Ting Kau Bridge (TKB) incurred with different types of structural damage. Then the improved novelty index is extended to formulate multi-novelty indices in terms of the measured modal frequencies and incomplete modeshape components for damage region identification. The capability of the formulated multi-novelty indices for damage region identification is also examined through numerical simulations of the TMB and TKB.

• Ocean and Polar Research
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• 제32권4호
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• pp.387-396
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• 2010

This paper estimates changes in the total factor productivity and technical efficiency change index and the technical change index using the Malmquist productivity index (MPI) in fishery-processed wholesale products over the time period spanning 2006-2008. The model considers a number of employees and operating costs as input factors, and sales and EBIT (earnings before tax and interest) as output factors. The results demonstrate that, between 2006 and 2007, there has generally been no technical progress, although a small improvement in productivity was detected in the sales scale of 10 billion won-50 billion won. Between 2007 and 2008, there was technical progress in the majority of DMU, except within the range of 20 million won-10 billion won. Wilcoxon's rank-sum test, however, demonstrates no statistically significant differences in productivity between the two periods.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2005년도 추계 학술논문 발표대회
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• pp.117-120
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• 2005

The business market of architecture has got a system that controls a deposit according to the price function. This system is written on a law of contract about countries. So the main body of construction has to make a reasonable contract. This study is written about a rate of numerical index on controling a deposit. We tried to fine problems and solutions of labor expenses, instrument costs and material costs which is so big and changable on the construction market Labor expenses are expressed according to the rate of construction scale between direct and indirect cost that applies ability of works. Instrument costs are expressed according to an output method of a unit price annually and a weight allowance of local instrument conditions and use frequence. The last material costs expressed according to a local weight allowance make a decision of the material cost index. They applies locally relative index more than absolute one on what uses the price rate of producers and importations. This solutions are not enough to apply to the real market, so it needs to exam and to be on the market after a feasibility study.

• Journal of Power Electronics
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• 제16권1호
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• pp.319-328
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• 2016

In this study, we first briefly introduce the effect of circulating current control on the modulation signal of a modular multilevel converter (MMC). The maximum modulation index is also theoretically derived. According to the optimal modulation index analysis and the model in the continuous domain, different DC-side output impedance equivalent models of MMC with/without compensating component are derived. The DC-side impedance of MMC inverter station can be regarded as a series xR + yL + zC branch in both cases. The compensating component of the maximum modulation index is also related to the DC equivalent impedance with circulating current control. The frequency characteristic of impedance for MMC, which is observed from its DC side, is analyzed. Finally, this study investigates the prediction of the DC voltage ripple transfer between two-terminal MMC high-voltage direct current systems under unbalanced conditions. The rationality and accuracy of the impedance model are verified through MATLAB/Simulink simulations and experimental results.

• 한국항해항만학회지
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• 제46권2호
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• pp.110-120
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• 2022

Spain is Europe's second-largest country with total throughput reaching 16.7 million twenty-foot equivalent units (TEU) by 2020. The purpose of this study was to measure and compare the efficiency of 17 container terminals. As a study method, the DEA-CCR model, undesirable variable, and Malmquist Index (MI) were used for data envelopment analysis (DEA). The study results are as follow: (1) DEA-CCR is used to evaluate basic efficiency. The most efficient terminals are decision-making units DMU 1 (APM Terminals (Algeciras Port)), DMU 2 (Total Terminal International Algeciras (Algeciras Port)) and DMU 5 (Barcelona Europe South Terminal (Barcelona Port)). (2) Undesirable DEA was conducted to suggest inefficiency from the undesirable output. Overall, the efficiency scores were reduced. However, DMU 1, DMU 2, and DMU 5 maintained efficiency scores regardless of the finish factor. (3) Malmquist Index was used to observe technology and efficiency changes dynamically. The changes in TCI affected Spanish container terminals more than the Technical Efficiency Change Index (TECI) in 2018-2019. However, in 2019-2020, the TECI was 2.706, higher than the TCI value, indicating that the change in TECI had more influence on the increase in productivity. This study offers a broader understanding of Spanish container terminals.

• 한국공작기계학회논문집
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• 제12권1호
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• pp.92-100
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• 2003

Using a quarter car model, an analytic method for performance estimation of a vehicle suspension system with respect to frequency response, RMS response and performance index is presented. From frequency response function, compromization of response performance to the whole frequency range is verified and from RMS response and performance index, sensitivity of ride md handling characteristics are examined. Using a full car model, sweet area(stable ride area) are determined and performance sensitivity is estimated according to the change of feedback gains. In order to esimate the output sensitivity, response we is displayed using a 3-dimensional contour plot. Design data n suggested for optimal design parameter esimation, which maximize the performance of the given suspension system.

• 융합신호처리학회 학술대회논문집
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• 한국신호처리시스템학회 2003년도 하계학술대회 논문집
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• pp.169-172
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• 2003

PID control has been well used for several decade. For PID algorithm, some tuning methods are used and with these parameters, control system is designed. But in some cases various kinds of performance are needed, so variable type of performance index must be utilized so that the designed control system meets the conditions. This paper presents some linear combinational type of performance index and with numerical methods, the PID parameters are obtained. Moreover I-PD type controller is used so that this two degree of freedom controller may give more desirable output characteristics. Simulations are done with MATLAB m file and mdl files.

• 한국수자원학회논문집
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• 제33권5호
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• pp.647-658
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• 2000

본 연구에서는 공급측면 산업연관분석모형을 사용하여 물공급지장이 끼치는 산업의 전방효과를 분석하고자 하였다. 여기서 분석된 공급지장비용은 수도사업의 신뢰도 결정에 사용될수 있으며 물의 공급부족이 발생할 경우 물의 효율적 배분을 위한 정책적 기초를 제공할 수 있다. 따라서 산업연관분석을 이용하여 수도부문이 차지하는 국민경제적 위치를 확인하고 공급지장으로 인한 산업간 직·간접 피해를 분석하였다. 또한 가뭄시 중요한 공급우선 순위 결정을 위한 공급지장지수를 제안하였다. 한편 가뭄의 발생은 지역적인 특성을 가지고 있어서 전국산업연관표를 이용한 지역수준의 공급지장비용이 과대 도는 과소평가될 여지가 있다. 따라서 경남지역산업연관표를 통해 산정한 공급지장비용을 전국산업관표와 비교·분석하였다.

• Journal of Chest Surgery
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• 제23권1호
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• pp.22-32
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• 1990

Postoperative cardiac performance of cyanotic congenital heart disease is somewhat different from that of other cardiac diseases. For the evaluation of postoperative cardiac performance in the cyanotic congenital heart disease we measured cardiac output by thermodilution technique at 1, 4, 8, 12, 16, 20, 24, 36, 48 postoperative hours in 14 patients operated from Feb. 1989 to Nov. 1989 in The Department of Thoracic and Cardiovascular Surgery, Seoul National University Children`s Hospital. At the same time, we checked left atrial pressure [LAP], central venous pressure [CUP], and mixed venous oxygen saturation [SvO2] to detect correlation between them. Immediate postoperative cardiac index was 3.585 $\pm$ 0.945 L/min/m2, and it decreased maximally to 3.322$\pm$1.007 L/min/m2 at postoperative 16 hours. After then it increased and stabilized from 36 hours after operation, and its value was 4.426$\pm$1.358 L/min/m2. There were no correlations between cardiac index and left atrial pressure or central venous pressure. Between mixed venous oxygen saturation and cardiac index, there was no correlation in the early postoperative period but after postoperative 16 hours, there was significant correlation between them and correlation coefficients were 0.573 [16hrs], 0.743 [20hrs], 0.436 [24hrs], 0.560 [36hrs], 0.636 [48hrs], respectively. From these results, we concluded that in the corrective surgery of cyanotic congenital heart disease, cardiac performance was depressed in the early postoperative period. It improved from postoperative 16 hours, and stabilized from 36 hours after operation. During early postoperative period, mixed venous oxygen saturation should not be used as a predictor of cardiac performance but it could be used as a predictor of cardiac performance from 16 hours after operation.

• 기술혁신연구
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• 제21권3호
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• pp.41-72
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• 2013

정보화 사회의 도래에 따른 정보통신기술의 발전과 활용이 국가 경제구조 및 성장에 급격한 영향을 미치고 있는 추세에 맞춰 본 연구는 자료포락분석과 맘퀴스트지수를 활용하여 국가별 정보통신기술의 활용성과를 상대적 효율성 및 생산성의 관점에서 접근하고자 하였다. 투입요소로 ICT환경과 ICT이용준비도 그리고 산출물로 ICT활용도를 이용하여 총 28개 국가를 대상으로 2008년부터 2011년 동안 정보통신기술 활용성과를 진단한 결과, 자료포락분석에서는 전체적인 ICT 효율성이 감소한 것으로 나타나 외형적 성장에 비해 실질적인 ICT 활용 부문은 부진한 것으로 판단되었고, 맘퀴스트지수 분석결과에서도 전체적인 ICT 생산성은 지난 3개년 구간동안 개선되지 않은 것으로 분석되었다. 이러한 분석결과를 종합적으로 고려해 볼 때, ICT 활용성과를 제고하기 위해서는 지금까지 추진해온 물리적 요소의 양적 투입에 의존하는 외형적 개발정책보다는 투입요소와 산출물을 합목적적으로 연계시키고 ICT 활용 효율성을 증진시킬 수 있는 다각적인 운영 합리화 방안이 필요하다고 본다.