• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 2003년도 ISIS 2003
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• pp.616-619
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• 2003

In this paper, we develop an input device equipped with accelerometers and gyroscopes. The installed sensors measure the inertial measurements i.e., accelerations and angular rates produced by the movement of the system when a user is writing on the plane surface or in the three dimensional space. The gyroscope measurement are integrated once to give the attitude of the system and consequently used to remove the gravity included in the acceleration measurements. The compensated accelerations bin doubly integrated to yield the position of the system. Due to the integration processes involved in recovering the users'motions, the accuracy of the position estimation significantly deteriorates with time. Among various error sources of the system incorrect estimation of attitude causes the largest portion of the positioning error since the gravity is not fully cancelled. In order to solve this problem, we propose a Kalman filler-based attitude estimation algorithm which fuses measurement data from accelerometers and gyroscopes by fuzzy logic approach. In addition, the online calibration of the gyroscope biases are performed in parallel with the attitude estimation to give more accurate attitude estimation. The effectiveness and the feasibility of the presented system is demonstrated through computer simulations and actual experiments.

• 한국산업정보학회논문지
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• 제21권4호
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• pp.1-11
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• 2016

본 연구는 Facebook 사용자들의 Like활동 정보를 사용하여 정치성향을 예측하기 위한 분석 모델과 프로그램를 개발하였다. Facebook의 Ajax사용 특성 을 반영한 Facebook 크로울러를 개발하였으며, 이를 사용하여 수집된 성기고 방대한 데이터의 상관 매트릭스 정보를 효과적의 축소하기 위한 카테고리 레벨 필터링 기법을 개발하였다. 대한민국 사용자들을 대상으로 LCA (Latent class analysis) 분석한 결과 28 개의 기준 (전체 대상페이지의 3% 미만) 으로 사용자의 정치적인 극성을 상당히 정확하게 (AUC of 0.82) 예측할 수 있음을 확인하였다.

• Journal of Advanced Marine Engineering and Technology
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• 제27권6호
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• pp.696-703
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• 2003

A photovoltaic power generation system is an infinite and clean energy system. Recently. because of the realization of high efficiency and low cost PV modules, the studies on the PV system have extensively increased. In this paper. we present an online scheme for parameter estimation of solar cell, based on the model adjustment technique and a real-coded genetic algorithm(RCGA). The ideal diode model and the diode model with series and shunt resistors are used to estimate their parameters, Simulation works using field data in the form of a V-I characteristic curve are carried out to demonstrate the effectiveness of the proposed method.

• Journal of Power Electronics
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• 제18권1호
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• pp.129-136
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• 2018

An accurate state-of-charge (SOC) estimation ensures the reliable and efficient operation of a lithium-ion battery management system. On the basis of a combined electrochemical model, this study adopts the forgetting factor least squares algorithm to identify battery parameters and eliminate the influence of test conditions. Then, it implements online SOC estimation with high accuracy and low run time by utilizing the low computational complexity of the unscented Kalman filter (UKF) and the rapid convergence of a particle filter (PF). The PF algorithm is adopted to decrease convergence time when the initial error is large; otherwise, the UKF algorithm is used to approximate the actual SOC with low computational complexity. The effect of the number of sampling particles in the PF is also evaluated. Finally, experimental results are used to verify the superiority of the combined method over other individual algorithms.

• Journal of Power Electronics
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• 제17권1호
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• pp.149-160
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• 2017

To improve the performance of sensorless induction motor (IM) drives, an adaptive speed estimation method based on a strong tracking extended Kalman filter with a least-square algorithm (LS-STEKF) for induction motors is proposed in this paper. With this method, a fading factor is introduced into the covariance matrix of the predicted state, which forces the innovation sequence orthogonal to each other and tunes the gain matrix online. In addition, the estimation error is adjusted adaptively and the mutational state is tracked fast. Simultaneously, the fading factor can be continuously self-tuned with the least-square algorithm according to the innovation sequence. The application of the least-square algorithm guarantees that the information in the innovation sequence is extracted as much as possible and as quickly as possible. Therefore, the proposed method improves the model adaptability in terms of actual systems and environmental variations, and reduces the speed estimation error. The correctness and the effectiveness of the proposed method are verified by experimental results.

• Journal of Power Electronics
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• 제15권2호
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• pp.411-418
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• 2015

In this paper, a new method for the online estimation of equivalent series resistances (ESR) of the DC-link capacitors in induction machine (IM) drive systems with a front-end diode rectifier is proposed, where the ESR estimation is conducted during the regenerative operating mode of the induction machine. In the first place, a regulated AC current component is injected into the q-axis current component of the induction machine, which induces the current and voltage ripple components in the DC-link. By processing these AC signals through digital filters, the ESR can be estimated by a recursive least squares (RLS) algorithm. To acquire the AC voltage across the ESR, the DC-link voltage needs to be measured at a double sampling frequency. In addition, the ESR current is simply reconstructed from the stator currents and switching states of the inverter. Experimental results have shown that the estimation error of the ESR is about 1.2%, which is quite acceptable for condition monitoring of the capacitor.

• 한국소프트웨어감정평가학회 논문지
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• 제16권1호
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• pp.45-53
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• 2020

본 논문에서는 웹 페이지 탐색 시 지속해서 발생하는 사용자 상호작용 과정을 이용하여 시선 검출을 위한 캘리브레이션 데이터를 획득하고, 사용자의 시선을 검출하는 동안 자연스럽게 캘리브레이션을 수행하는 방법에 관하여 기술하였다. 제안된 비강압식 캘리브레이션은 획득한 캘리브레이션 데이터를 이용하여 미리 학습된 시선 검출 CNN 모델을 새로운 사용자에 적응하도록 보정하는 과정이다. 이를 위해 훈련을 통해서 시선을 검출하는 일반화된 모델을 만들고 캘리브레이션에서는 온라인 학습 과정을 통해 빠르게 새로운 사용자에 적응하도록 하였다. 실험을 통하여 다양한 사용자 상호작용의 조합으로 시선 검출 모델을 캘리브레이션 하여 성능을 비교하였으며, 기존 방법 대비 개선된 정확도를 얻을 수 있었다.

• 한국의류학회지
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• 제31권12호
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• pp.1721-1732
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• 2007

본 연구는 온라인 의사결정과정에서 온라인 쇼핑속성, 정보원 및 구매의도와 관련된 소비자 정보탐색의 경로모델을 밝히고자 하였다. 연구대상은 미국 남서부지역의 대학교에 재학중인 대학생으로 표본으로 설문조사 하였으며, 총 219명의 이용 가능한 자료가 수집되었다. 자료분석을 위해 요인분석과 LISREL8.53을 이용하여 경로분석을 실시하였다. 연구결과, 소비자의 온라인 의복구매를 위한 정보원은 온라인 정보원, 소매점 정보원, 대중매체의 세 가지 유형으로 분류되었다. 특히, 온라인 의복구매를 위해 소매점 정보원(점포내 디스플레이, 제조업체의 팜플렛 또는 카달로그)을 더 많이 이용하는 것으로 나타났다. 추정된 경로모델을 살펴보면, 온라인 쇼핑속성의 중요도가 정보탐색에 유의한 영향을 미쳤다. 특히 온라인 의복 구매시, 소비자의 온라인 정보원 이용은 거래관련속성 즉 구매유인서비스(incentive service)에 의해 가장 크게 영향을 받는 반면, 소매점 정보원 이용은 심미성, 가격 등의 제품 및 시장관련속성의 중요도에 의해 더 크게 영향을 받는 것으로 나타났다. 또한 소비자의 세가지 탐색유형 모두 구매의도에 정적인 효과를 보이고 있었으며, 다른 정보원에 비해, 소매점 정보원 이용이 온라인 의복구매의도에 가장 큰 효과를 보였다. 따라서, 본 연구는 온라인 쇼핑속성별 소비자의 차별화된 정보탐색 패턴이 온라인 구매의도를 증가시키고 있음을 확인함으로써, 의류제품의 멀티채널 소매전략(Multi-channel retailing) 방향이 논의되었다.

• KDI Journal of Economic Policy
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• 제39권1호
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• pp.83-102
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• 2017

Price control can restore efficiency in some cases, but an uncarefully designed policy fails to restore efficiency, yields side effects, or even exacerbates efficiency losses. This paper shows that the copyright royalty rule, which takes the greater of ad valorem royalties and perunit royalties, tends to fix the prices of final goods at a specific level. Such a rule weakens competition as it prevents prices from decreasing even when market conditions change, having negative effects on social welfare as well as consumer surplus. Counterfactual analyses using estimation results in the Korean online music service industry show that firms could have profitably reduced prices if the ad valorem rule had been applied instead, although they did not have an incentive to do so under the original combination rule.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 Ⅳ
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• pp.2200-2203
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• 2003

In an active noise control(ANC) system using the Filtered-X least mean square(LMS) algorithm, the online secondary path modeling method by exploiting a random noise generator is applied. This method is suitable for secondary path modeling. However, it is increased the residual error of the ANC system. In this paper, we presents an ANC system improved online secondary path modeling method which is modified Kuo and Zhang model that is the secondary path estimation by the additive noise. In addition, our proposed model is used that additive noise is transformed into the signal multiplied reference signal by gain control parameter and delayed.