• Smart Structures and Systems
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• 제1권4호
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• pp.325-338
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• 2005

Utilizing robotic based reconfigurable nodal structural health monitoring systems has many advantages over static or human positioned sensor systems. However, creating a robot capable of traversing a variety of civil infrastructures is a difficult task, as these structures each have unique features and characteristics posing a variety of challenges to the robot design. This paper outlines the design and implementation of a novel robotic platform for deployment on ferromagnetic structures as an enabling structural health monitoring technology. The key feature of this design is the utilization of an attachment device which is an advancement of the common magnetic base found in the machine tool industry. By mechanizing this switchable magnetic circuit and redesigning it for light weight and compactness, it becomes an extremely efficient and robust means of attachment for use in various robotic and structural health monitoring applications. The ability to engage and disengage the magnet as needed, the very low power required to do so, the variety of applicable geometric configurations, and the ability to hold indefinitely once engaged make this device ideally suited for numerous robotic and distributed sensor network applications. Presented here are examples of the mechanized variable force magnets, as well as a prototype robot which has been successfully deployed on a large construction site. Also presented are other applications and future directions of this technology.

• 한국환경보건학회지
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• 제36권3호
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• pp.208-214
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• 2010

Green tobacco sickness (GTS) is an illness associated with nicotine exposures among tobacco harvesters. The purposes of this study were to measure the concentration of nicotine residues on the hands and forearms of tobacco harvesters, and to compare the concentrations according to the harvesting task. Wipe samples from the both hands and forearms were obtained from 16 workers at three sampling times (before work, in the morning after harvesting leaves, and in the afternoon after binding leaves). The geometric means of the right and left hand nicotine levels in harvesting work were 0.70 and $0.61\;{\mu}g/cm^2$, respectively, which were substantial, if significantly lower than the corresponding levels in binding work of 5.19 and $1.50\;{\mu}g/cm^2$ (p=0.016). The overall combined nicotine levels for the hands (i.e., left and right) were significantly higher than those for the forearms (p=0.013). The results of this study therefore indicate that, for GTS prevention, waterproof gloves should be worn while harvesting.

• Smart Structures and Systems
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• 제4권6호
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• pp.779-794
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• 2008

Observer-based fault detection and isolation (FDI) filter design method is a model-based method. By carefully choosing the observer gain, the residual outputs can be projected onto different independent subspaces. Each subspace corresponds to the monitored structural element so that the projected residual will be nonzero when the associated structural element is damaged and zero when there is no damage. The key point of detection filter design is how to find an appropriate observer gain. This problem can be interpreted in a geometric framework and is found to be equivalent to the problem of finding a decentralized static output feedback gain. But, it is still a challenging task to find the decentralized controller by either analytical or numerical methods because its solution set is, generally, non-convex. In this paper, the concept of detection filter and iterative LMI technique for decentralized controller design are combined to develop an algorithm to compute the observer gain. It can be used to monitor structural element state: healthy or damaged. The simulation results show that the developed method can successfully identify structural damages.

• International Journal of Automotive Technology
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• 제6권5호
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• pp.545-554
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• 2005

Passive velocity field control (PVFC) was previously developed for fully mechanical systems, in which the motion task was specified by behaviors in terms of a velocity field and the closed-loop was passive with respect to the supply rate given by the environment input. However, the PVFC was only applied to a single manipulator. The proposed control law was derived geometrically and the geometric and robustness properties of the closed-loop system were also analyzed. In this paper, we propose a virtual passivity-based algorithm to apply decentralized control to multiple 3­wheeled mobile robotic systems whose subsystems are under nonholonomic constraints and convey a common rigid object in a horizontal plain. Moreover, it is shown that multiple robot systems ensure stability and the velocities of augmented systems converge to a scaled multiple of each desired velocity field for cooperative mobile robot systems. Finally, the application of proposed virtual passivity-based decentralized algorithm via system augmentation is applied to trace a circle and the simulation results is presented in order to show effectiveness for the decentralized control algorithm proposed in this research.

• 한국측량학회지
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• 제37권5호
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• pp.331-341
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• 2019

With the popularity of sensor-rich environments, smartphones have become one of the major platforms for obtaining and sharing information. Since it is difficult to utilize GNSS (Global Navigation Satellite System) inside the area with many buildings, the localization of smartphone in this case is considered as a challenging task. To resolve problem of localization using smartphone a four step image-based localization method and procedure is proposed. To improve the localization accuracy of smartphone datasets, MMS (Mobile Mapping System) and Google Street View were utilized. In our approach first, the searching for candidate matching image is performed by the query image of smartphone's using GNSS observation. Second, the SURF (Speed-Up Robust Features) image matching between the smartphone image and reference dataset is done and the wrong matching points are eliminated. Third, the geometric transformation is performed using the matching points with 2D affine transformation. Finally, the smartphone location and attitude estimation are done by PnP (Perspective-n-Point) algorithm. The location of smartphone GNSS observation is improved from the original 10.204m to a mean error of 3.575m. The attitude estimation is lower than 25 degrees from the 92.4% of the adjsuted images with an average of 5.1973 degrees.

• Nuclear Engineering and Technology
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• 제53권12호
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• pp.3944-3951
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• 2021

Several reasons such as no free lunch theorem indicate that there is not a universal Feature selection (FS) technique that outperforms other ones. Moreover, some approaches such as using synthetic dataset, in presence of large number of FS techniques, are very tedious and time consuming task. In this study to tackle the issue of dependency of estimation accuracy on the selected FS technique, a methodology based on the heterogeneous ensemble is proposed. The performance of the major learning algorithms of neural network (i.e. the FFNN-BR, the FFNN-LM) in combination with the diverse FS techniques (i.e. the NCA, the F-test, the Kendall's tau, the Pearson, the Spearman, and the Relief) and different combination techniques of the heterogeneous ensemble (i.e. the Min, the Median, the Arithmetic mean, and the Geometric mean) are considered. The target parameters/transients of Bushehr nuclear power plant (BNPP) are examined as the case study. The results show that the Min combination technique gives the more accurate estimation. Therefore, if the number of FS techniques is m and the number of learning algorithms is n, by the heterogeneous ensemble, the search space for acceptable estimation of the target parameters may be reduced from n × m to n × 1. The proposed methodology gives a simple and practical approach for more reliable and more accurate estimation of the target parameters compared to the methods such as the use of synthetic dataset or trial and error methods.

• 한국수학교육학회지시리즈C:초등수학교육
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• 제26권1호
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• pp.45-63
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• 2023

패턴의 규칙을 찾는 활동은 초등학생들의 대수적 사고를 신장하는 데 유용하다. 본 논문은 초등학생들에게 패턴활동을 지도하는 세 가지 주요 활동, 즉 패턴의 구조를 분석하는 활동, 규칙을 찾아 특정한 항을 구하는 활동, 규칙을 찾아 표현하는 활동을 중심으로 2015 개정 수학과 교육과정에 따른 초등학교 4학년 검정 교과용 도서의 '규칙찾기' 단원에 제시된 패턴 활동의 지도 방안을 분석하였다. 분석 결과 10종 도서에서 증가 수 패턴, 증가 기하 패턴, 계산식 패턴을 중심으로 세 가지 활동이 제시되어 있었다. 패턴의 구조를 분석하는 활동은 대부분 증가 기하패턴을 다룰 때 제시되어 있었는데, 주로 패턴을 이루는 모형의 개수를 구하는 데 초점을 두었다. 반면 규칙을 찾아 특정한 항을 구하는 활동은 세 가지 패턴에서 고루 제시되어 있었고, 대개 가까운 항을 구하는 문항이 많았다. 규칙을 찾아 표현하는 활동은 자신의 언어로 규칙을 이야기해 보거나 써보도록 제시되어 있었다. 이와 같은 분석결과를 토대로 본 연구는 초등학생들의 대수적 사고를 신장하기 위한 패턴 활동의 지도 방안에 대해 교과용 도서의 구성 및 활용 측면에서 구체적인 시사점을 제공한다.

• 한국멀티미디어학회논문지
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• 제16권2호
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• pp.254-268
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• 2013

본 논문에서는 마비/편마비 환자의 손 재활운동을 위한 증강현실 인터랙션을 통한 재활운동시스템을 제안한다. 주로 기계적 장치에 의존하고 있는 기존의 마비환자 재활운동시스템에서 가정에서 손쉽게 재활훈련을 수행할 수 있도록 시스템을 구성하기위하여 컴퓨터 비전 기법을 이용하여 재활훈련에 필요한 장비를 최소화하고 좀 더 간편하게 설치하여 사용할 수 있도록 하는데 초점을 맞추었다. 본 논문에서 제안된 방법은 손끝의 움직임과 상태를 손끝마커의 위치와 접촉여부를 검사함으로써 인터랙션 상태를 점검한다. 한대의 카메라로부터 입력되는 손끝 마커의 2차원 위치는 3차원 객체와의 인터랙션을 위하여 ARToolKit 마커를 기반으로 보정된 3차원 카메라 공간상의 좌표로 변환되어 사용된다. 3차원 좌표계로 변환과정을 거친 손끝 마커의 3차원 위치는 3차원 객체와의 인터랙션에 반영함으로써 증강현실 기반의 인터랙션을 구현하였다. 본 논문에서 제시한 인터랙션 기법의 구현내용을 실험결과에서 나타내었고, 증강현실 기반 테이블탑 환경에서 마비환자의 재활운동에 활용될 수 있음을 나타내었다.

• 컴퓨터교육학회논문지
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• 제12권4호
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• pp.57-64
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• 2009

단백질 구조 비교는 각 단백질에 존재하는 수많은 원자들을 처리해야 하므로 많은 컴퓨팅 자원을 요구하는 작업이다. 이러한 작업을 처리하기 위한 접근법으로써 그리드 환경에서 시간 소모가 큰 계산 작업을 분산 처리하는 것이 널리 사용되어 왔다. 그러나 이러한 그리드 환경을 통제하는 것은 비전문가들에게 쉽지 않을 수 있다. 본 논문에서는 비전문가들도 쉽게 그리드 환경을 통제할 수 있는 JXTA 기반의 단백질 구조 비교 시스템을 제안한다. 쿼리 단백질과 비슷한 단백질들을 찾기 위해 사전처리 단계 와 인식단계로 구성된 기하학적 해싱 알고리즘이 사용되었다. 실험 결과에 의하면 주어진 쿼리 단백질 구조와 일치하는 단백질 구조를 시스템이 정확히 찾고 또한 제안된 시스템은 쉽게 단백질 다킹 문제를 해결하도록 확장될 수도 있다. 본 논문에서 제안하는 시스템은 비전문가들, 특히 생물학이나 화학을 전공하는 대학생들처럼 일반적으로 분산 시스템에 대한 숙련된 지식이 없는 사용자들에게 도움이 되리라 기대된다.

• 한국CDE학회논문집
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• 제17권6호
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• pp.417-425
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• 2012

In recent years, great attention has been paid to using simple physical objects as tangible objects to improve user interaction in augmented reality (AR) environments. In this paper, we address AR-based user interaction using tangible objects, which has been used as a key component for virtual design evaluation of engineered products including digital handheld products. We herein consider the use of two types (product-type and pointer-type) of tangible objects. The user creates input events by touching specified parts of the product-type object with the pointer-type object, and the virtual product reacts to the events by rendering its visual and auditory contents on the output devices. The product-type object is used to reflect the geometric shape of a product of interest and to determine its position and orientation in the AR environment. The pointer-type object is used to recognize the reference position of the pointer (or finger) in the same environment. The rapid prototype of the product is employed as a good alternative to the product-type object, but various alternatives to the pointer-type object can be considered according to fabrication process and touching mechanism. In this paper, we present four alternatives to the pointer-type object and investigate their strong and weak points by performing experimental comparison of their various aspects including interaction accuracy, task performance, and qualitative user experience.