• 전기학회논문지
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• 제56권8호
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• pp.1491-1497
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• 2007

This paper considers robust and non-fragile guaranteed cost controller design method for descriptor systems with parameter uncertainties and time delay, and static state feedback controller with gain variations. The existence condition of controller, the design method of controller, the upper bound to minimize guaranteed cost function, and the measure of non-fragility in controller are proposed using linear matrix inequality (LMI) technique, which can be solved efficiently by convex optimization. Therefore, the presented robust and non-fragile guaranteed cost controller guarantees the asymptotic stability and non-fragility of the closed loop systems in spite of parameter uncertainties, time delay, and controller fragility.

• Educational Technology International
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• 제21권1호
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• pp.69-95
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• 2020

The purpose of this research is to analyze the predictive powers of the five technostress creators - techno-overload, techno-invasion, techno-complexity, techno-insecurity, and techno-uncertainty - in job satisfaction and teacher efficacy of primary school teachers in Korea when they incorporated mobile technology into teaching. A questionnaire was designed to measure the level of teacher's stress from technology, job satisfaction and teacher efficacy. Data were collected from 164 teachers. Multiple regression analysis was conducted to explain which area of technostress led to varying degrees of job satisfaction and teacher efficacy. The results showed that techno-complexity alone predicted both job satisfaction and teacher efficacy. The reason why techno-complexity was the only predictor is that teachers would have first needed to understand how to incorporate mobile technology into teaching, before feeling overloaded, invaded, insecure, or uncertain about it, meaning techno-complexity precedes other constructs. Therefore, the only stress factor that affected them was how to understand the complexity of mobile technology. This calls for adequate training and support from schools and governments in order for the teachers to fully incorporate technology into teaching.

• 대한인간공학회지
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• 제25권3호
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• pp.49-60
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• 2006

Technological encroachment provides human operators with flood of information that must be analyzed to understand the environment and make judgments that lead to strategic actions. Further, the environment is not static and therefore uncertain, changing its aspect dynamically. Complexity accompanied with its dynamics imposes substantial difficulty to human operators' task. Criticality of having situational understanding becomes more important than ever. Situationalunderstanding requires the human operators possessing tacit knowledge in order for them to make the sense out of the situation while interacting with information from many heterogeneous sources, the notion of sensemaking. Sensemaking refers to the process of developing mental framework to assemble pieces of information representing different aspects of the environment that can be used to develop one's own actionable knowledge to implement their judgments in the uncertain environment. Therefore, judgment process and performance is a key component of sensemaking process. Among many judgment and decision making models, the lens model with its extension can be utilized to partially describe the judgmental aspect of sensemaking. One of the lens model parameters, unmodeled knowledge, can be a corresponding quantitative measure for the tacit knowledge that plays an important role in sensemaking. In this paper, a comprehensive literature for sensemaking is provided to formally define the notion of sensemaking in the military domain. Also, it is proposed that there is a crucial link between the sensemaking and human judgment process and performance from the lens model perspective. Potential implications for experimental framework are also proposed.

• 대한기계학회논문집A
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• 제36권11호
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• pp.1327-1334
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• 2012

본 논문은 4차 동적 시스템인 구동기를 구성하는 부품들의 변량 및 공기외란의 변량으로 인해 구동기 성능에 변량이 존재할 때, 구동기의 성능을 순응도 기반으로 최적화한 설계 결과를 제시하였다. 구동기는 BLDC 모터와 평기어 및 웜기어 조립체, 카나드로 구성된다. 구동기의 성능은 시간에 따라 변화하는 카나드 각도 정보를 이용하여 평가하였다. 고차 시스템의 성능은 해석적 접근을 통해 시스템 변수들의 함수로 표현하기 어렵기 때문에 반응표면모델을 기반으로, F-검정을 수행하여 유효한 시스템 변수들을 선정한 후 성능을 유효한 시스템 변수들의 함수로 근사화하였다. 본 연구에서 변량을 가지는 구동기 성능의 규격에 대한 순응도를 확률값으로 정의하였다. 순응도를 최적화하여 구한 설계변수는 부품 및 공기외란에 변량이 존재하더라도 고려한 규격을 모두 만족시킬 수 구동기를 제공할 수 있다.

• 한국지능시스템학회논문지
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• 제10권3호
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• pp.218-227
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• 2000

본 논문에서는 시소러스에 근거한 새로운 퍼지 정보검색 기법을 제안한다. 제안된 방법에서 시소러스는 내부 용어들 간의 관련도를 정성적인 언어 갑으로 갖는 퍼지 언어 매트릭스로 표현되며 용어들간의 관계는 동의, 계층, 그릭 연관이 세 가지 관계가 제공된다 싯러스 내부 용어들 간이 무시된 관련도가 퍼기 이론에 근거한 퍼지이론에 근거한 퍼지 언어 매트릭스의 전이 폐쇄 알고리즘에 의해 추론된다 또한 제안돈 방법은 사용자의 질의, 그리고 문서와 같은 정보 항목의 표현에도 인간이 주관적이고 부정확한 측도를 그대로 반영하는 정성적인 언어 값을 허용한다. 따라서 논문 [1-3]에서 제안된 방법보다 좀 더 유용하다. 또한 질의 평가시 퍼지 언어 매트릭스와 AON(Associated Ordinary Number)값을 이용하기 때문에 논문 [1-3]에서 사용되는 방법보다 시간적으로 효츌적이다. 결과적으로 사용자가 좀 더 유용하고 지능적인 방법으로 질의를 처리할 수있도록 한다

• 한국CDE학회논문집
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• 제19권4호
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• pp.305-315
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• 2014

It is important to predict and measure the combat effectiveness (CE) of weapons system in battlefield for acquiring efficient weapon system. Moreover, quantitative calculation of weapon effectiveness under complicated and uncertain battlefield environment is also difficult based on the future network centric warfare. Many papers used the term of combat effectiveness and tried to study a lot of related issues about it. However, there is no paper dealing with the classification of study issue about CE and what will happen in this study field. In this paper, we proposed how to classify the study issue about CE and forecast future direction of this study field. Conceptually, CE is nothing but the assessment results to measure the ability of a military weapon system to accomplish its objective. We believe that it is an appropriate time to review the literature extensively on CE analysis because the research interests and the papers of CE are rapidly growing in these days. This paper reviewed many CE analysis papers, classified them according to their research content and the research methodology applied. Additionally, a comprehensive list of future research areas is also given.

• Structural Monitoring and Maintenance
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• 제6권4호
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• pp.317-346
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• 2019

Performance assessment of pavements proves useful, in terms of handling the ride quality, controlling the travel time of vehicles and adequate maintenance of pavements. Roughness profiles provide a good measure of the deteriorating condition of the pavement. For the accurate estimates of pavement roughness from dynamic vehicle responses, vehicle parameters should be known accurately. Information on vehicle parameters is uncertain, due to the wear and tear over time. Hence, condition monitoring of pavement requires the identification of pavement roughness along with vehicle parameters. The present study proposes a scheme which estimates the roughness profile of the pavement with the use of accurate estimates of vehicle parameters computed in parallel. Pavement model used in this study is a two-layer Euler-Bernoulli beam resting on a nonlinear Pasternak foundation. The asphalt topping of the pavement in the top layer is modeled as viscoelastic, and the base course bottom layer is modeled as elastic. The viscoelastic response of the top layer is modeled with the help of the Burgers model. The vehicle model considered in this study is a half car model, fitted with accelerometers at specified points. The identification of the coupled system of vehicle-pavement interaction employs a coupled scheme of an unbiased minimum variance estimator and an optimization scheme. The partitioning of observed noisy quantities to be used in the two schemes is investigated in detail before the analysis. The unbiased minimum variance estimator (MVE) make use of a linear state-space formulation including roughness, to overcome the linearization difficulties as in conventional nonlinear filters. MVE gives estimates for the unknown input and fed into the optimization scheme to yield estimates of vehicle parameters. The issue of ill-posedness of the problem is dealt with by introducing a regularization equivalent term in the objective function, specifically where a large number of parameters are to be estimated. Effect of different objective functions is also studied. The outcome of this research is an overall measure of pavement condition.

• 한국생산제조학회지
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• 제19권4호
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• pp.529-538
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• 2010

This paper presents a reliability-based topology optimization (RBTO) based on bidirectional evolutionary structural optimization (BESO). In design of a structure, uncertain conditions such as material property, operational load and dimensional variation should be considered. Deterministic topology optimization (DTO) is performed without considering the uncertainties related to the design variables. However, the RBTO can consider the uncertainty variables because it can deal with the probabilistic constraints. The reliability index approach (RIA) and the performance measure approach (PMA) are adopted to evaluate the probabilistic constraints in this study. In order to apply the BESO to the RBTO, sensitivity number for each element is defined as the change in the reliability index of the structure due to removal of each element. Smoothing scheme is also used to eliminate checkerboard patterns in topology optimization. The limit state indicates the margin of safety between the resistance (constraints) and the load of structures. The limit State function expresses to evaluate reliability index from finite element analysis. Numerical examples are presented to compare each optimal topology obtained from RBTO and DTO each other. It is verified that the RBTO based on BESO can be effectively performed from the results.

• 한국지능시스템학회논문지
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• 제21권6호
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• pp.761-766
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• 2011

Hedge는 불확실함을 나타내는 언어적 표현으로, 저자가 자신의 글에 내포된 내용이 불확실하거나 의심이 갈 때 사용한다. 이러한 불확실성 때문에 hedge가 포함된 문장은 사실이 아닌 문장으로 간주된다. 문장이 사실인지 아닌지를 판단하는 것은 여러 응용에서 사용될 수 있는데, 정보검색, 정보추출, 질의응답 등의 응용분야에서 전처리 과정으로 사용되어, 보다 정확한 결과를 얻게 한다. 본 논문에서는 한국어 hedge 말뭉치를 구축하고, 이로부터 hedge 단서 어구들을 추출하여 일반화된 단서어구 패턴을 구축한 후, 한국어 hedge 인식 실험을 하였다. 실험을 통하여 78.6%의 F1-measure값을 얻을 수 있었다.

• Journal of Korea Trade
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• 제24권6호
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• pp.1-18
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• 2020

Purpose - This study investigates whether a listing effect exists in cross-border M&As and whether the effect can be attributed to the uncertainty of the GDP growth rate in the target firm's home country. We apply a joint variable analysis using M&A announcement data from the Korea Exchange (KRX), Shanghai Stock Exchange (SSE), and the Taiwan Stock Exchange (TWSE) from 2004 to 2013. We also conduct an event study using the measure of the uncertainty of the GDP growth rate (based on IMF statistics) in 55 target countries. Design/methodology - We measure the abnormal return (AR) using the market-adjusted model. We test the significance of the AR and the cumulative abnormal return (CAR) using a one-sample t-test. We examine the characteristics of the CARs depending on whether the target company is listed by applying a difference analysis using CAR as a test variable. In addition, we set CAR (-5, +5) as a dependent variable to identify the cause of the listing effect, and test both the financial characteristic variables of the acquirer and the collective characteristic variables of the merger as independent variables in the multiple regression analysis. Findings - First, we find the listing effect of cross-border M&As in the KRX, SSE, and TWSE, which represent the capital markets in Korea, China, and Taiwan, respectively. This listing effect persists during the global financial crisis and has a negative effect on the wealth of acquiring shareholders, especially when the target countries are emerging markets. Second, greater uncertainty regarding the target countries' economic growth in cross-border M&As has a negative effect on the wealth of acquiring firms' shareholders. Third, our empirical analysis demonstrates that the listing effect is attributable to the fact that firms listed in a target country with greater uncertainty of economic growth are more directly and greatly exposed to uncertain capital markets through stock markets, than are unlisted firms. Originality/value - This study is significant in that it presents a new strategic perspective in the study of cross-border M&As by demonstrating empirically that the listing effect is attributable to the uncertainty regarding the economic development of the target firms' home countries.