• Smart Structures and Systems
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• 제14권5호
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• pp.765-784
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• 2014

In comparison with conventional shape memory actuated structures, antagonistic shape memory alloy (SMA) actuators permits a fully reversible two-way response and higher response frequency. However, excessive internal stress could adversely reduce the stroke of the actuators under repeated use. The two-way shape memory effect might further decrease the range of the recovered strain under actuation of an antagonistic SMA actuator unless additional components (e.g., spring and stopper) are added to regain the overall actuation capability. In this paper, the performance of all four possible types of SMA actuation schemes is investigated in detail with emphasis on five key properties: recovered strain, cyclic degradation, response frequency, self-sensing control accuracy, and controllable maximum output. The testing parameters are chosen based on the maximization of recovered strain. Three types of these actuators are antagonistic SMA actuators, which drive with two active SMA wires in two directions. The antagonistic SMA actuator with an additional pair of springs exhibits wider displacement range, more stable performance under reuse, and faster response, although accurate control cannot be maintained under force interference. With two additional stoppers to prevent the over stretch of the spring, the results showed that the proposed structure could achieve significant improvement on all five properties. It can be concluded that, the last type actuator scheme with additional spring and stopper provide much better applicability than the other three in most conditions. The results of the performance analysis of all four SMA actuators could provide a solid basis for the practical design of SMA actuators.

• The Journal of the Acoustical Society of Korea
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• 제17권1E호
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• pp.30-35
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• 1998

Given a noisy sampled at equispaced points with white noise, we consider problems where the signal to be recovered is known to be positive; for example, images, chemical spectra or other measurements of intensities. Shrinking noisy wavelet coefficients via thresholding offers very attractive alternatives to existing methods of recovering signals from noisy data. In this paper, we propose a method of recovering the original signal from a corrupted noisy signal, guaranteeing the recovered signal positive. We first obtain wavelet coefficients by thresholding, and use a nonlinear optimization to find the denoised signal which must be positive. Numerical examples are used to illustrate the performance of the proposed algorithm.

• ETRI Journal
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• 제43권2호
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• pp.344-356
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• 2021

CRAFT is a tweakable block cipher introduced in 2019 that aims to provide strong protection against differential fault analysis. In this paper, we show that CRAFT is vulnerable to side-channel cube attacks. We apply side-channel cube attacks to CRAFT with the Hamming weight leakage assumption. We found that the first half of the secret key can be recovered from the Hamming weight leakage after the first round. Next, using the recovered key bits, we continue our attack to recover the second half of the secret key. We show that the set of equations that are solvable varies depending on the value of the key bits. Our result shows that 99.90% of the key space can be fully recovered within a practical time.

• 전자공학회논문지
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• 제51권1호
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• pp.97-103
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• 2014

본 논문에서는 1/8-rate 위상검출기를 이용한 클록-데이터 복원회로를 제안한다. 기존의 full-rate 또는 half-rate 위상검출기의 사용은 동일 데이터 속도에서 복원된 클록의 주파수가 상대적으로 높아야 하므로 샘플링회로와 VCO의 설계에 부담으로 작용한다. 본 논문에서는 복원된 클록의 주파수를 낮추기 위해 1/8-rate 클록을 사용할 수 있는 위상검출기를 구성하고 Linear equalizer를 위상검출기 입력에 사용하여 복원된 클록의 지터를 감소시켰다. 테스트 칩은 0.13-${\mu}m$ CMOS 공정으로 제작되었고 입력은 3-Gb/s PRBS 데이터 패턴, 동작전압은 1.2-V에서 측정되었다.

• 자원ㆍ환경경제연구
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• 제23권1호
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• pp.133-156
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• 2014

경제구조를 표현하는 식들로 구성된 모형을 이용하여 도출되는 정량적 분석결과는 성과의 크기를 제시하므로 정책을 평가할 때에 유용하다. 이에 본 논문에서는 해외석유 가스개발사업의 국민경제에 대한 효과를 정량적으로 측정하기 위하여 해외석유 가스개발사업을 반영한 거시경제모형을 구축하고, 이를 이용하여 해외석유 가스개발사업으로부터의 회수액이 GDP, 경상수지, 실업률, 소비자물가, 환율 등에 미치는 효과를 분석하였다. 해외석유 가스개발 사업의 회수액은 우리나라 기업이 해외석유 가스개발사업에 참여하여 획득한 석유 또는 가스를 달러 형태로 금액화한 것이다. 해외석유 가스개발사업을 반영한 거시경제모형은 한국은행의 모형(1997, 2004, 2012)을 이용하여 구축하였으며, 개별 행태방정식의 통계적 적합성과 historical simulation을 통해 모형 전체의 안정성을 확인하였다. 분석결과에 따르면 시간이 경과하면서 해외석유 가스개발사업 회수액의 규모가 커지면서 우리 나라의 거시경제 변수에 미치는 효과의 크기도 커졌다. 변수별로 보면 해외석유 가스개발사업은 경상수지, 실질 GDP, 실업률에 대해서 긍정적인 효과를 유도하였다. 이에 비해서 소비자물가에 대해서는 상승하는, 그리고 환율에 대해서는 하락(원화가치의 평가절상)하는 효과를 보였다. 매해마다 효과의 크기는 다르지만, 2011년 기준으로 해외석유 가스개발사업 회수액은 경상수지를 2.226%, 실질 GDP를 0.401% 증가시키고, 실업률을 0.489%p 감소시켰다. 소비자물가는 0.101% 증가시키고, 원/달러환율은 0.379% 낮추었다.

• 한국정보처리학회논문지
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• 제7권5호
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• pp.1491-1499
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• 2000

This paper is designed and implemented the data recovery mechanism for 2-D (2-dimensional) bar code system. The data recovery algorithm used the modified Reed-Solomon algorithm and it is implemented into 2-D bar code system. There are 7 types of 2-D bar code system, which are 21x21, 25x25, 41x41, 73x73, 101x101, 177x177. This paper has been experimented that how many data is saved among several 2-D bar code types and how many data re recovered. In the first experiment, the big size 2-D bar code system has many ECC codeword. Therefore, original data cannot be assigned to 2-D bar code system. In the second experiment, even if 35∼40% loss dta for the 2-D bar code system, the 2-D bar code system could have been recovered to original data.

• Journal of Astronomy and Space Sciences
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• 제35권4호
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• pp.243-252
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• 2018

In a satellite gravimetry mission similar to GRACE, the precision of inter-satellite ranging is one of the key factors affecting the quality of gravity field recovery. In this paper, the impact of ranging precision on the accuracy of recovered geopotential coefficients is analyzed. Simulated precise orbit determination (POD) data and inter-satellite range data of formation-flying satellites containing white noise were generated, and geopotential coefficients were recovered from these simulated data sets using the crude acceleration approach. The accuracy of the recovered coefficients was quantitatively compared between data sets encompassing different ranging precisions. From this analysis, a rough prediction of the accuracy of geopotential coefficients could be obtained from the hypothetical mission. For a given POD precision, a ranging measurement precision that matches the POD precision was determined. Since the purpose of adopting inter-satellite ranging in a gravimetry mission is to overcome the imprecision of determining orbits, ranging measurements should be more precise than POD. For that reason, it can be concluded that this critical ranging precision matching the POD precision can serve as the minimum precision requirement for an on-board ranging device. Although the result obtained herein is about a very particular case, this methodology can also be applied in cases where different parameters are used.

• 대한기계학회논문집
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• 제17권9호
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• pp.2271-2279
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• 1993

In the case of life prediction on the structures and machines after long service, it is natural to consider a degradation problems. Most of degradation data form practical structures are isolated data obtained at the time of periodical inspection or repair. From such data, it may be difficult to obtain the degradation curve available and necessary for life prediction. In this paper, for the purpose of obtaining a degradation curves, developed the simulate degradation method and fatigue test and Charpy impact test were conducted on the degraded, simulate degraded and recovered materials. Fatigue life prediction were conducted by using the relationship between fracture transition temperature (DBTT : vTrs) obtained from the Charpy impact test through the degradation process and fatigue crack growth constants of m and C obtained from the fatigue test.

• 대한산업공학회지
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• 제34권1호
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• pp.32-41
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• 2008

This paper studies a joint EOQ and EPQ model in which a stationary demand can be satisfied by recycled products as well as newly purchased products. The model assumes that a fixed quantity of the used products are collected from customers and later recovered for reuse. The recovered products are regarded as perfectly new ones. We also assume that the number of orders for newly purchasing items and the number of recovery setups in a cycle can be mutually independent integers. Under these assumptions, we develop an optimization model obtaining the economic order quantity for newly procured products, the optimal lot size for the recovery process, and the sequence of the orders and the setups, simultaneously. And then a simple solution procedure to find a local optimal control parameter set is proposed. To validate the model and the solution procedure, finally, some computational experiments are presented.

• 수산경영론집
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• 제40권3호
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• pp.29-49
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• 2009

There are various types of predictable economic benefits to restoring beneficial uses from contaminated marine sediment cleanup. These benefits can be derived from reduction in aquatic animals died or infected, increase in their consumption recovery, increase in tourism including recreational fishing, reduction in human health risk, increase in amenity and aesthetics, increase in ecosystem integrity, and so on. The paper focuses on estimating the net increase in value for producers and consumers from producing and consuming those fish due to the pollution reduction of marine contaminated cleanup project. Almost Ideal Demand System(AIDS) is employed for estimate of the demand for fish, and the production cost function for fish are determined using market data. The result shows 10.8 billion won per year for economic surplus to the net increase for producers and consumers.