• 대한조선학회 특별논문집
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• 대한조선학회 2008년도 특별논문집
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• pp.68-75
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• 2008

This paper describes the design and implementation of a low cost inertial navigation system(INS) using an inertial measurement unit(IMU), a digital compass, GPS, and an embedded system. The system has been developed for a transporter that load and unload ship blocks in a shipbuilding yard. When the transporter would move from place to place, they would periodically pass under obstructions that would obscure the GPS signal. This increases the error when estimating the position. Thus the INS has been used to improve position accuracy. INS is also capable of providing continuous estimates of the transporter's position and orientation. Even though IMU is typically very expensive, this INS is made of "low cost" components and the indirect Kalman filtering algorithm.

• Advances in concrete construction
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• 제3권2호
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• pp.127-143
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• 2015

Steel fibre reinforced concrete (SFRC) is an anisotropic material due to the random orientation of the fibres within the cement matrix. Fibres under different inclination angles provide different strength contribution of a given crack width. For that the pull-out response of inclined fibres is of great importance to understand SFRC behaviour, particularly in the case of fibres with hooked ends, which are the most widely used. The paper focuses on the numerical modelling of the pull-out response of this kind of fibres from high-strength cementitious matrix in order to study the effects of different inclination angles of the fibres to the load-displacement pull-out curves. The pull-out of the fibres is studied by means of accurate three-dimensional finite element models, which take into account the nonlinearities that are present in the physical model, such as the nonlinear bonding between the fibre and the matrix in the early stages of the loading, the unilateral contact between the fibre and the matrix, the friction at the contact areas, the plastification of the steel fibre and the plastification and cracking of the cementitious matrix. The bonding properties of the fibre-matrix interface considered in the numerical model are based on experimental results of pull-out tests on straight fibres.

• 대한전기학회논문지
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• 제39권1호
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• pp.36-48
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• 1990

브러쉬없는 직류전동기의 위치제어시 새로운 제어방법을 제시하였다. 일반적으로 브러쉬없는 직류전동기의 모델식은 비선형특성을 갖는다. 이 비선형특성을 벡터제어에 근거한 filed orientation방법으로 선형화시켰고, 선형화된 시스템에 새로운 상태변수를 첨가한 상태변수 궤환(augmented state variable feedback)방법이 적용될 수 있음을 보였다. 또한 부하외란을 미지의 입력으로 본 0-관측기(0-observer)로 부터 관측하고 여기서 얻은값을 이용하여 응답이 빠른 feedforward로 보상하였다. 이로써 전체시스템의 응답특성을 변화시키지 않고도 외란에 안정한(robust)특성이 얻어짐을 보였다. 전체 시스템은 마이크로 프로세어 MC68000을 이용한 디지탈 제어기로 구현하였고, 각 제어 알고리즘에 대한 시뮬레이션 및 실험결과로 제안된 제어알고리즘의 효과를 보였다.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제49권8호
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• pp.557-564
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• 2000

A very simple control approach using neural network for the robust position control of a Permanent Magnet Synchronous Motor(PMSM) is presented. The linear quadratic controller plus feedforward neural network is employed to obtain the robust PMSM system approximately linearized using field-orientation method for an AC servo. The neural network is trained in on-line phases and this neural network is composed by a feedforward recall and error back-propagation training. Since the total number of nodes are only eight, this system can be easily realized by the general microprocessor. During the normal operation, the input-output response is sampled and the weighting value is trained multi-times by error back-propagation method at each sample period to accommodate the possible variations in the parameters or load torque. In addition, the robustness is also obtained without affecting overall system response. This method is realized by a floating-point Digital Signal Processor DS1102 Board (TMS320C31).

• 센서학회지
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• 제19권3호
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• pp.209-213
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• 2010

This paper describes the fabrication and characteristics of AlN piezoelectric MPG(micro power generator). The micro energy harvester was fabricated to convert ambient vibration energy to electrical power as a AlN piezoelectric cantilever with Si proof-mass. To be compatible with CMOS process, AlN thin film was grown at low temperature by RF magnetron sputtering and micro power generators were fabricated by MEMS technologies. X-ray diffraction pattern proved that the grown AlN film had highly(002) orientation with low value of FWHM(full width at the half maximum, $\theta=0.276^{\circ}$) in the rocking curve around(002) reflections. The implemented harvester showed the $198.5\;{\mu}m$ highest membrane displacement and generated 6.4 nW of electrical power to $80\;k{\Omega}$ resistive load with $22.6\;mV_{rms}$ voltage from 1.0 G acceleration at its resonant frequency of 389 Hz. From these results, the AlN piezoelectric MPG will be possible to suitable with the batch process and confirm the possibility for power supply in portable, mobile and wearable microsystems.

• International Journal of Automotive Technology
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• 제7권3호
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• pp.361-367
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• 2006

This paper describes a novel stereo vision based localization of free parking site, which recognizes the target position of automatic parking system. Pixel structure classification and feature based stereo matching extract the 3D information of parking site in real time. The pixel structure represents intensity configuration around a pixel and the feature based stereo matching uses step-by-step investigation strategy to reduce computational load. This paper considers only parking site divided by marking, which is generally drawn according to relevant standards. Parking site marking is separated by plane surface constraint and is transformed into bird's eye view, on which template matching is performed to determine the location of parking site. Obstacle depth map, which is generated from the disparity of adjacent vehicles, can be used as the guideline of template matching by limiting search range and orientation. Proposed method using both the obstacle depth map and the bird's eye view of parking site marking increases operation speed and robustness to visual noise by effectively limiting search range.

• 한국정밀공학회지
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• 제18권12호
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• pp.177-184
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• 2001

C3M(chemical mechanical micro machining) is applied for diminishing the size of burr and fabricating the massless patterning for aluminium wafer(thickness of 1${\mu}m$). It is difficult to perform the micro size machining with the radically increased shear stress. While the miniaturization and function-orientation of parts has been needed in the many field such as electronics, optics and medicine. etc., it is not enough to satisfy the industry needs in the machining technology. In this paper feasibility test of diminishing burr and fabricating maskless pattern was experimented and analyzed. In the experiment oxide layer was farmed on the aluminium with chemical reaction by ${HNO_3}$(10wt%), then the surface was grooved with tungsten carbide tool for the different condition such as the load and fred rate. The result was compared with the conventional machining to show the improvement of C3M with SEM for burr diminish and XPS for atomic existence, AFM for more precise image.

• Structural Engineering and Mechanics
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• 제57권1호
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• pp.45-63
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• 2016

Fiber metal laminates (FMLs) represent a high-performance family of hybrid materials which consist of thin metal sheets bonded together with alternating unidirectional fiber layers. In this study, the buckling behavior of a FML circular cylindrical shell under axial compression is investigated via both analytical and finite element approaches. The governing equations are derived based on the first-order shear deformation theory and solved by the Navier solution method. Also, the buckling load of a FML cylindrical shell is calculated using linear eigenvalue analysis in commercial finite element software, ABAQUS. Due to lack of experimental and analytical data for buckling behavior of FML cylindrical shells in the literature, the proposed model is simplified to the full-composite and full-metal cylindrical shells and buckling loads are compared with the available results. Afterwards, the effects of FML parameters such as metal volume fraction (MVF), composite fiber orientation, stacking sequence of layers and geometric parameters are studied on the buckling loads. Results show that the FML layup has the significant effect on the buckling loads of FML cylindrical shells in comparison to the full-composite and full-metal shells. Results of this paper hopefully provide a useful guideline for engineers to design an efficient and economical structure.

• 설비공학논문집
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• 제16권10호
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• pp.960-968
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• 2004

One of the most important functions of a building is to provide thermally comfortable indoor environmental conditions for the occupants. Therefore, a great deal of energy is consumed for heating and cooling to satisfy those thermal requirements. In order to provide thermal comfort with minimum heating and cooling energy consumption, optimal design of building affecting indoor climate is required. This study used the TRNSYS for modeling and simulation of the energy flows of residential building types, and examined the energy efficient measures to reduce the thermal loads. The residential building types are classified into the detached house, apartment house and high-rise residential complex. The results of the simulation show that the heating energy consumption in the detached house is especially high, whereas the cooling load is an important determinant in the apartment house and high-rise residential complex. The measures examined are the insulation thickness, various types of glazing, infiltration, natural and controlled ventilation, solar shading, orientation and etc. Comparative evaluations and sensitivity analyses revealed the effects of these variables and identified their energy efficient building design strategies.

• 한국식생활문화학회지
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• 제34권3호
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• pp.277-283
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• 2019

This study explore the market segmentation based on beer consumers' purchase motivation 1) to analyze beer consumers and markets more closely and 2) to demonstrate the characteristics of each market segment and contribute to marketing strategies with beer consumer segment. Using -administrated questionnaires asked questions recognizable beer purchase within 6 months by over 20-years-olds, this study 201 surveys online 22 days. The results as follows: beer consumers' purchase motivation consisted of three factors enhancement, social orientation, and value enhancement. Cluster analysis based on beer purchase showed that there were three groups motivation multi-motivation and motivation group based on average value of beer purchase motive factors and relative load per factor. demographic,beer drinking characteristics and group difference according to cluster gender and monthly average income, and beer drinking characteristics also significantly different by preferred beer, preferred beer type, occasion and drinking place.