• 대한기계학회논문집
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• 제16권4호
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• pp.803-810
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• 1992

본 연구에서는 서산등과 Nishiyama등이 제시한 특이점 분포법에 의한 기초식 을 비선형으로 해석하기 위하여 익과 유한한 길이의 캐비티의 자유유선에 용출, 와, 이중용출 등의 특이점을 분포시켜서 수퍼캐비테이션을 발생시키는 익열의 유동장을 지 배하는 비선형의 적분방정식을 복소포텐셜로 나타내고 경계 요소법을 이용하여 수치계 산함으로써 수퍼비테이션익열의 유동에서의 수력특성을 구하는 데 있다.

• Structural Engineering and Mechanics
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• 제31권1호
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• pp.39-56
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• 2009

Vibration is an undesirable phenomenon in a dynamic system like lightly damped aerospace structures and active vibration control has gradually been employed to suppress vibration. The objective of the current investigation is to introduce an active torsional magneto-rheological (MR) fluid based damper for vibration control of a typical nose landing gear. They offer the adaptability of active control devices without requiring the associated large power sources. A torsional damper is designed and developed based on Bingham plastic shear flow model. The numerical analysis is carried out to estimate the damping coefficient and damping force. The designed damper is fabricated and an experimental setup is also established to characterize the damper and these results are compared with the analytical results. A typical FE model of Nose landing gear is developed to study the effectiveness of the damper. Open loop response analysis has been carried out and response levels are monitored at the piston tip of a nose landing gear for various loading conditions without damper and with MR-damper as semi-active device. The closed-loop full state feedback control scheme by the pole-placement technique is also applied to control the landing gear instability of an aircraft.

• 말소리와 음성과학
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• 제9권4호
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• pp.107-114
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• 2017

The purpose of the current study was to compare selected acoustic and electroglottographic measures (closed quotient, pitch, and loudness) among vowel phonation, traditional voiced lip trill ($VLT_T$), modified voiced lip trill methods ($VLT_M$). A total of 21 participants without voice complaints produced 4-second long samples using each phonation method. Results indicated that mean closed quotient of $VLT_M$ was higher than that of vowel phonation and $VLT_T$, while its range and standard deviation measures were higher than those of vowel phonation. Mean, range, standard deviation, maximum of pitch measures of $VLT_M$ were higher than those of vowel phonation. Lastly, mean and maximum loudness of the $VLT_M$ were higher than $VLT_T$. In conclusion, the current data indicate the possibility to use the $VLT_M$ as a training method for singing or a strategy to facilitate generalization effect of voice therapy. Current results also reflect the necessity for further study pertaining to the long-term effect of the $VLT_M$ training method. Clinical implications are discussed.

• Journal of Biosystems Engineering
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• 제25권4호
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• pp.273-278
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• 2000

The hybrid heat pump system of the air to air and / or air to water was composed and its COP was analyzed with the ambient temperature on the opened and closed loop system respectively. The results be indicated by the equation(7) that the COP(Coefficient of Performance) of air-source(air to air and / or air-water) heat pump is effected with the ambient air temperature and AVACTHE.(Automatic Variable Area Capillary Type Heat Exchanger) 2. The COP of air-to-water heat pump without AVACTHE decreased in accordance with the ambient temperature decrease, however in case of the heat pump with AVACTHE the COP was maintained at 2.8∼3.0 level when the ambient temperature decrease from -$5^{\circ}C$ to $-11^{\circ}C$. 3. The COP of the air-to-water heat pump operated on the open loop was higher 40∼58% than that of the heat pump operated on the close loop. 4. The lower ambient temperature air effect on the COP of the air-to-air heat pump operated on the semi closed loop could be controlled using the AVACTHE, and at the high ambient air temperature the COP increased using the Bypass circuit.

• International Journal of Computer Science & Network Security
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• 제24권1호
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• pp.187-195
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• 2024

This is an extended paper explaining the role of E-learning and quality development in the current situation. Amid Covid:19, E-Learning has achieved a new miles stone in imparting education and all levels of institutions have transformed their learning platform from face to face to virtual learning. In this scenario E-Learning is facing two major challenges, first to ensure the ability of computer systems or software to exchange and make use of information on virtual platform (interoperability) and secondly, developing quality learning through e-Learning. To impart learning and teaching (L&T) through E-learning, Middle East University (MEU) has adopted Learning Management Services (LMS) through Blackboard. The university has three types of L&T methods; full online, Blended and Supportive. This research studies the concept, scope and dimensions of interoperability (InT) of E-Learning in MEU then the connection and interdependence between with quality development. In this paper we have described the support and the importance of finest standards and specifications for the objectives of InT of E-Learning and quality development in MEU. The research is based principally on secondary data observed from MEU E-Learning deanship. Also sample of 20 E-Learning experts at MEU were given closed ended as well as semi closed questionnaires for evaluating the assurance of InT of E-Learning and quality development. These experts are mainly certified online facilitators and admin staff. Results provide the verification of application and presence of InT of E-Learning and assured the quality development process in MEU.

• 지구물리와물리탐사
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• 제14권3호
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• pp.185-190
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• 2011

해양전자탐사의 모델링에서 1차장은 송수신 간격이 넓어지면 크게 감소하기 때문에 기존의 선형필터로서는 정확한 계산이 어려워진다. 그러나 균질 반무한공간의 경우 TM 모드의 Hankel 변환에는 해석해가 존재하므로 이를 이용하면 Hankel 변환의 계산을 위한 선형필터의 정확도를 검토할 수 있다. 그 결과 송수신 간격이 커짐에 따라서 전자기장이 반대수 그래프에서 선형적으로 감소하는 경우는 총 36가지 송수신 조합 중 9가지 뿐이며, 나머지 조합에서는 전자기장이 0 이거나 아니면 공기층의 영향을 받아 전자기장의 감소가 크지 않다. 다행히 이 9가지 조합에는 해석해가 존재하고, 나머지 조합에서는 전자기장의 극단적인 감소가 나타나지 않으므로 비교적 길이가 짧은 필터로도 Hankel 변환의 정확한 계산이 가능하다. 이상의 결과를 토대로 이 논문에서는 균질 반무한공간 모델에 대한 전자기장 계산법으로서 TM 모드의 Hankel 변환에는 해석해를 쓰고 TE 모드 계산에는 그 계수가 61개인 필터를 쓰는 방식을 제안한다.

• 한국안전학회지
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• 제22권4호
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• pp.13-19
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• 2007

An numerical method to estimate thermal diffusivity has been developed for one-dimensional unsteady heat conduction problem, when the temperatures are know at two positions in a semi-infinite body. Using the closed form solution which has already derived an explicit solution for the inverse problem for one-dimensional transient heat conduction using Laplace transform technique, we first estimate the surface temperature. The thermal diffusivity can be estimated by using the estimated surface temperature and measured temperatures, which include some uncertainties. The estimated surface heat flux and thermal diffusivity are found to be in good agreement with those of the experimented conditions. This method will be extended to the simultaneous measurement of thermal diffusivity and thermal conductivity.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.530-535
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• 2004

This paper considers a state set estimation (SSE) based model predictive control (MPC) for linear parameter- varying (LPV) systems with input constraint. We estimate, at each time instant, a feasible set of all states which are consistent with system model, measurements and a priori information, rather than the state itself. By combining a state-feedback MPC and an SSE, we design an SSE-based MPC algorithm that stabilizes the closed-loop system. The proposed algorithm is solved by semi-de�nite program involving linear matrix inequalities. A numerical example is included to illustrate the performance of the proposed algorithm.

• IEIE Transactions on Smart Processing and Computing
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• 제5권3호
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• pp.153-163
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• 2016

Local feature extraction methods for images and videos are widely applied in the fields of image understanding and computer vision. However, robust features are detected differently when using the latest feature detectors and descriptors because of diverse image environments. This paper analyzes various feature extraction methods by summarizing algorithms, specifying properties, and comparing performance. We analyze eight feature extraction methods. The performance of feature extraction in various image environments is compared and evaluated. As a result, the feature detectors and descriptors can be used adaptively for image sequences captured under various image environments. Also, the evaluation of feature detectors and descriptors can be applied to driving assistance systems, closed circuit televisions (CCTVs), robot vision, etc.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1997년도 추계학술대회 논문집
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• pp.31-36
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• 1997

Thermal expansion of the ball screw in semi-closed loop type CNC Lathe directly affects the position precision along the travel axis. In this paper, the thermal displacement of the ball screw is estimated by using macro variables. The estimated displacements of the ball screw are managed by calculating the interval of pitch error rate in the NC. The thermal behaviour of the ball screw of the CNC Lathe, under the constant operating conditions, was measured to examine the effectiveness of this compensation method. The results showed that thermal displacement of the ball screw could be maintained its accuracy better than 6${\mu}{\textrm}{m}$ while applying this method.