• Journal of Electrical Engineering and Technology
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• 제13권2호
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• pp.648-658
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• 2018

Regarding the fact that wind power forecast accuracy is gradually improved as time is approaching, this paper proposes a two-stage rolling dispatch approach based on model predictive control (MPC), which contains an intra-day rolling optimal scheme and a real-time rolling base point tracing scheme. The scheduled output of the intra-day rolling scheme is set as the reference output, and the real-time rolling scheme is based on MPC which includes the leading rolling optimization and lagging feedback correction strategy. On the basis of the latest measured thermal unit output feedback, the closed-loop optimization is formed to correct the power deviation timely, making the unit output smoother, thus reducing the costs of power adjustment and promoting wind power accommodation. We adopt chance constraint to describe forecasts uncertainty. Then for reflecting the increasing prediction precision as well as the power dispatcher's rising expected satisfaction degree with reliable system operation, we set the confidence level of reserve constraints at different timescales as the incremental vector. The expectation of up/down reserve shortage is proposed to assess the adequacy of the upward/downward reserve. The studies executed on the modified IEEE RTS system demonstrate the effectiveness of the proposed approach.

• 한국국방경영분석학회지
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• 제31권2호
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• pp.28-44
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• 2005

The previous studies approach the field artillery fire scheduling problem as deterministic and do not explicitly include information on the potential scenario changes. Unfortunately, the effort used to optimize fire sequences and reduce the total time of engagement is often inefficient as the collected military intelligence changes. Instead of modeling the fire sequencing problem as deterministic model, we consider a stochastic artillery fire scheduling model and devise a solution methodology to integrate possible enemy attack scenarios in the evaluation of artillery fire sequences. The goal is to use that information to find robust solutions that withstand disruptions in a better way, Such an approach is important because we can proactively consider the effects of certain unique scheduling decisions. By identifying more robust schedules, cascading delay effects will be minimized. In this paper we describe our stochastic model for the field artillery fire sequencing problem and offer revised robust stochastic model which considers worst scenario first. The robust stochastic model makes the solution more stable than the general two-stage stochastic model and also reduces the computational cost dramatically. We present computational results demonstrating the effectiveness of our proposed method by EVPI, VSS, and Variances.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2002년도 춘계종합학술대회
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• pp.167-170
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• 2002

본 논문에서는 다양한 기동표적에 대해 적은 연산량으로 효과적인 추적을 위한 방법에 대해 기술한다. 일반적으로 사용하는 KF는 기동하지 않는 표적의 추적에는 효과적인 반면 표적이 기동하는 경우에는 열악한 추적 성능을 발휘한다. 이에 대해 여러 운동상태를 고려한 IMM이 적합한 대안으로 고려된다. 하지만 IMM은 모델의 수가 증가할수록 연산량이 증가한다는 제한사항을 가지고 있다. 따라서 기동표적 추적에서 IMM의 제한사항을 보완하기 위해 KF를 Two-Stage로 나누어 각각 필터링을 수행하는 Optimal Two-Stage Kalman Estimator (OTSKE)를 IMM 구조에 적용하고 더 나아가 기존의 IAC 알고리즘에 적용하여 IMM과 유사한 추적성능을 발휘하면서도 연산량은 약 58% 감소시킬 수 있었다.

• 응용통계연구
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• 제28권1호
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• pp.93-102
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• 2015

D-최적 등을 위시한 최적실험은 비선형모형인 경우 추정을 하여야할 모수에 의존하는 문제점이 존재한다. 따라서 기본적으로 문헌에서는 모수추정을 위해서는 순차실험을 제안한다. 본 연구에서는 2단계 실험설계를 모수추정의 사례를 포함한 다양한 환경 하에서의 사용방법을 알아보았다. 본 연구에서 제안한 내용은 단계의 수나 구체적인 실험기준의 숫자에 상관없이 적용되는 범용적인 기준이다. 본 연구는 2단계 실험에서 3개 이상의 실험목적을 가지고 있는 경우 하이브리드(hybrid)방법을 제안하였다. 모든 실험은 근사실험설계의 형태로 논의되었다.

• Structural Engineering and Mechanics
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• 제43권3호
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• pp.311-320
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• 2012

The higher-order asymptotic C(t) - $A_2(t)$ approach was employed to investigate the crack-tip stress of two collinear cracks in a power-law creeping material under the plane strain conditions. A comprehensive calculation was made of the single crack, collinear crack model with S/a = 0.4 and 0.8, by using the C(t) - $A_2(t)$ approach, HRR-type field and the finite element analysis; the latter two methods were used to check the constraint significance and the calculation accuracy of the C(t) - $A_2(t)$ approach, respectively. With increasing the creep time, the constraint $A_2$ was exponentially increased in the small-scale creep stage, while no discernible dependency of the constraint $A_2$ on the creep time was found at the extensive creep state. In addition, the creep time and the mechanical loads have no distinct influence on accuracy of the results obtained from the higher-order asymptotic C(t) - $A_2(t)$ approach. In comparison with the HRR-type field, the higher-order asymptotic C(t) - $A_2(t)$ solution matches well with the finite element results for the collinear crack model.

• 대한전기학회논문지:시스템및제어부문D
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• 제49권2호
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• pp.81-87
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• 2000

This paper presents a new approach to the synthesis of two-dimensional arrays such as Atmel 6000 series FPGAs using internal don't cares. Basically complex terms which fits to the linear array of cells without further routing wires are generated and they are collected by OR/XOR operations. In previous methods, complex terms are collected only by XOR operations, which may not be effective for nearly unate functions. In this paper, we allow complex terms to be collected by OR operations in addition to XOR operations. First, complex terms that lies in the ON-set of the function are generated and collected by OR operations. The sub-function realized by the first stage becomes an internal don't cares and they are exploited in the second stage which generates complex terms collectable by XOR operation. Experimental results shows the efficacy of the proposed method compared to the previous methods.

• JSTS:Journal of Semiconductor Technology and Science
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• 제9권4호
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• pp.233-239
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• 2009

A mixed CT/DT 2-1 cascaded ${\Sigma\Delta}M$ which includes a first stage CT ${\Sigma\Delta}M$ and a second stage mismatch insensitive two-channel time-interleaved DT ${\Sigma\Delta}M$ is proposed. With this approach, the advantages of both CT and DT ${\Sigma\Delta}Ms$ including high speed operation, inherent anti-aliasing filter, and good coefficient matching can be achieved. The two-channel time-interleaved ${\Sigma\Delta}M$ used in the second stage alleviates the speed constraints of the DT ${\Sigma\Delta}M$, whereas enables better matching between the analog and digital filter coefficients compared to CT ${\Sigma\Delta}Ms$.

• Asian Journal of Innovation and Policy
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• 제7권1호
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• pp.178-189
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• 2018

In this paper, we present a case study of a new emerging business startup involved in smart house appliances. The irreversible investment concept and real-option theory are introduced as the fundamentals of the model. By using games theory we show that the startup's actions can trigger reactions from other firms. The first part covers initial the research and development stage, while the second part covers production and commercialization. The findings of this study suggest that, given a certain amount of initial investment, an open and shared innovation may lead to hurting a firm's investment while strengthening the competitors' position in the market. However, given the sensitivity analysis, when volatility and demand grow favorably, sharing R&D investment is not a bad option for a new player to adjust its position in the market while still maintaining positive returns.

• Clinics in Shoulder and Elbow
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• 제25권3호
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• pp.202-209
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• 2022

Background: The purpose of our study was to investigate short-term outcomes of two-stage reverse total shoulder arthroplasty (RTSA) with an antibiotic-loaded cement spacer for shoulder infection. Methods: Eleven patients with shoulder infection were treated by two-stage RTSA following temporary antibiotic-loaded cement spacer. Of the 11 shoulders, nine had pyogenic arthritis combined with complex conditions such as recurrent infection, extensive osteomyelitis, osteoarthritis, or massive rotator cuff tear and two had periprosthetic joint infection (PJI). The mean follow-up period was 29.9 months (range, 12-48 months) after RTSA. Clinical and radiographic outcomes were evaluated using the visual analog scale (VAS) score for pain, American Shoulder and Elbow Surgeons (ASES) score, subjective shoulder value (SSV), and serial plain radiographs. Results: The mean time from antibiotic-loaded cement spacer to RTSA was 9.2 months (range, 1-35 months). All patients had no clinical and radiographic signs of recurrent infection at final follow-up. The mean final VAS score, ASES score, and SSV were significantly improved from 4.5, 38.6, and 29.1% before RTSA to 1.7, 75.1, and 75.9% at final follow-up, respectively. The mean forward flexion, abduction, external rotation, and internal rotation were improved from 50.0°, 50.9°, 17.7°, and sacrum level before RTSA to 127.3°, 110.0°, 51.8°, and L2 level at final follow-up, respectively. Conclusions: Two-stage RTSA with antibiotic-loaded cement spacer yields satisfactory short-term clinical and radiographic outcomes. In patients with pyogenic arthritis combined with complex conditions or PJI, two-stage RTSA with an antibiotic-loaded cement spacer would be a successful approach to eradicate infection and to improve function with pain relief.

• Journal of Mechanical Science and Technology
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• 제20권11호
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• pp.1834-1847
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• 2006

A robust minimum-time control (RMTC) strategy is addressed and it is extended to the dual-stage servo design. Rather than conventional switching type sub-optimal controls, it is a reference following control approach where the predetermined minimum-time trajectory (MTT) is tracked by the perturbation compensator based feedback controller. First, the minimum-time trajectory for a mass-damper system is derived. Then, the perturbation compensator to achieve robust tracking performance in spite of model uncertainty and external disturbance is suggested. The RMTC is also applied to the dual-stage positioner which consists of coarse actuator and fine one. To best utilize the actuation redundancy of the dual-stage mechanism, a null-motion controller to actively regulate the relative motion between the two stages is formulated. The performance of RMTC is validated through simulation and experiment.