• 항공우주시스템공학회지
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• 제14권1호
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• pp.68-73
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• 2020

본 논문은 산악 지형, 도심, 함정, 교량 등에서 수직 이·착륙 비행, 제자리 비행, 고정익기처럼 저속 및 고속비행을 할 수 있는 덕티드 추진체를 사용한 수직 이·착륙 초소형 무인 항공기 개발 동향을 기술한다. 이 항공기는 여러 측면에서 헬리콥터와 고정익기와는 비행 특성이 다르다. 미육군 미래 전투 체계와 DARPA의 OAV 프로그램의 목적은 운용자에 안전하고 낮은 음향 특성을 갖는 수직 이·착륙 덕티드 팬 초소형 무인 항공기 개발이다. 현재의 초소형 무인 항공기에 영상/적외선 카메라를 탑재하고 숲이나 언덕 뒤에 숨어 있는 적을 정지비행과 응시로 약 1 시간 동안 감시 및 정찰을 한다. OAV의 Class-I은 개인 병사가 배낭에 담아 운반할 수 있는 크기와 무게의 수직 이·착륙 덕티드 MAV 개발이다. Class-II는 Class-I보다 두 배의 운용 시간과 더 넓은 범위의 비행이 가능한 유기체의 수직 이·착륙 덕티드 팬 초소형 무인 항공기 개발이다. 초소형 무인기는 장시간 운용을 위해 현재의 '호버 및 응시'에서 '퍼치-앤-응시'으로 기술을 발전시켜야 한다. 근 미래의 OAV 개념은 유·무인 지상 차량이 주행하는 동안에 차량의 상부에 자동 이착륙하고, 탑재된 상태로 이동하고, 재급유, 재충전, 재이륙하는 합동 운용으로 임무 능력과 효율성을 확장하는 것이다. 덕티드 MAV는 지상 차량의 착륙 패드에서 자동으로 이착륙하기 위해 저렴한 초소형 GPS를 활용한 고정밀 상대 위치 기술 개발이 필요하다. 또한, VTOL 덕티드 MAV와 유·무인 지상 차량 간에 유기체의 협업 동작이 가능케하는 공통 명령과 제어 아키텍처를 개발할 필요가 있다.

• 정보와 통신
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• 제12권8호
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• pp.53-64
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• 1995

이 글에서는 국내의 PCS 표준 방식을 결정하기 위한 판단 기준과 여러 가지 고려 사항을 제시하고 이러한 기준에 의한 평가 결과 upbanded IS-95가 가장 적절한 방식임을 설명하였다. 그리고 CDMA 방식의 신규 셀룰라 사업자인 신세기 통신이 upbanded IS-95 방식의 PCS사업을 하기에 가장 적합한 사업자임을 논하였다. 그 다음 신세기 통신의 PCS 연구개발 추진 방안과 전략을 설명하였다. PCS 시스템 개발을 위해 국내제조업체와 추진하고 있는 공동개발에 관련한 사항을 기술하였다. 그리고 향후의 연구개발 추진 계획을 주요 항목별로 설명하였다. 지금까지 신세기통신이 추진해왔던 연구개발의 내용과 성과를 설명하고 그 중에서 PCS 망구성과 향후 제공하게 될 음성서비스, 부가서비스 및 무선 데이터서비스에 대한 사항을 설명하였다.

• 제어로봇시스템학회논문지
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• 제20권2호
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• pp.193-199
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• 2014

In this paper, we present an overview of the structure of a lab-built powered knee prosthesis and the control of it. We build a powered prosthesis prototype on the basis of previous researches and aim at obtaining the essential technology related with its control. We adopt the slider-crank mechanism with a DC motor as an actuator to manipulate the knee joint. We also build an embedded control system for the prosthesis with a 32-bit DSP controller as a main computation unit. We divide the gait phase into five stages and use a FSM (Finite State Machine) to generate a torque reference needed for each stage. We also propose to use a position-based impedance controller for driving the powered knee prosthesis stably. We perform some walking experiments at fixed speeds on a tread mill in order to show the feature of the built powered prosthesis. The experimental results show that our prosthesis has the ability to provide a functional gait that is representative of normal gait biomechanics.

• Journal of Information Technology Applications and Management
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• 제12권4호
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• pp.173-195
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• 2005

As the amount of informatization investment is rapidly increasing in many organizations, it becomes more inevitable to manage computing resources (information systems, computing facilities and manpower etc.) effectively. Specially, in public sector It is thought to be very important to achieve the economy of scale by integrating computing resources which are managed individually in many agencies. Also, our government have been recently making much efforts to raise the effectiveness of operating the information systems by promoting joint information use among many public agencies, enhancing the operating systems and the expertise of IS staff and applying the optimal information security systems. This study focuses on presenting the framework to effectively integrate omputing resources and proposing the ways of constructing and operating the integrated computing environment for the institutions and the affiliated groups under the Ministry of Culture & Tourism which are in charge of implementing cultural informatization. The main implications of this study are 1) building the ideal model of the integrated computing environment architecture suitable to cultural informatization area, 2) showing the criteria of deciding whether the organizations use the Integrated computing environment or not and how extensively they commit their computing resources to it, and 3) suggesting the ways of the phased integration and the change management to minimize confusion in the process of adopting the integrated computing environment and behavioral problems such as conflict and resistance of IS-related Personnel Influenced by Implementing the integrated computing environment.

• Journal of Welding and Joining
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• 제25권2호
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• pp.43-48
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• 2007

Laser Transmission Joining (LTJ) of plastics is a process in which light of suitable wavelength is transmitted through a transparent substrate that is in contact with an absorbing one. In this paper, LTJ is investigated by preliminary experiments from the viewpoint of mechanical engineering. To understand transmitting characteristics of each polymer substrate, transmission rate, reflection rate and absorption coefficient of polymer are measured by using a laser power-meter. Characteristics of joining in the spot welding and seam welding are investigated by measuring the fracture load. Fracture load increases in accordance to the laser power and irradiation time. However, when the laser power is over 60W and irradiation time over 4seconds, fracture load decreases. This phenomenon is probably due to heat-softening of materials. Besides, cavities are generated at a joint by evaporation of water molecules, which can be suppressed by introduction of a gap between two substrates.

• KCI Concrete Journal
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• 제14권3호
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• pp.102-110
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• 2002

Results of an experimental study on the pullout behavior of the headed reinforcement are presented. A total of 48 pullout tests was performed to evaluate pullout strengths and load-displacement behaviors in pullout of the headed bars. The square steel heads had gross area of 4 $A_{b}$ and thickness of $d_{b}$ The test program consisted of three pullout test groups: Simple and Edge pullout tests using plain concrete slabs, comparison of pullout performances between the standard hooks and the headed reinforcement, and pullout tests of headed reinforcement using reinforced concrete columns. Test variables included concrete strengths ( $f_{c}$' = 27.1MPa, 39.1MPa), reinforcing bar diameters (D16~D29), embedment depths (6 $d_{b}$~12 $d_{b}$), edge conditions, column reinforcement, and single-vs.-multiple bar pullout. Test results revealed that the heads effectively provided the pullout resistances of the deformed bars in tension. The load-displacement behaviors were similar between the 90-degree hooks and the headed reinforcement. When a multiple number of headed bars installed with small head-to-head spacings was pulled out, reinforcement designed to run across the concrete failure surface in a direction parallel to the headed bars helped improve the pullout performances of the headed reinforcement.t.ement.t.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제11권4호
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• pp.229-237
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• 2011

As smart phones have become widely adopted, they have brought about changes in individual lifestyles, as well as significant changes in the industry. As the mobile technology of smart phones has become associated with all areas of industry, it is not only accelerating innovation in other industries such as shopping, healthcare service, education, and finance, but is also creating new markets and business opportunities. The preparation of thorough security measures for smart phones is increasing in demand. While offering excellent mobility and convenience, smart phones can be exposed to a range of violation threats. In particular, it is necessary to make efforts to develop a security system that can preemptively cope with potential security threats in the banking service area, which requires a high level of reliability. This paper suggests a security reference model that is considered for the smart phone-based joint mobile banking development project being undertaken by the Bank of Korea in 2010. The purpose of this study is to make a security reference model for a reliable smart phone-based mobile financial service, by recognizing the specific security threats directed toward smart phones, and providing countermeasures to these security threats. The proposed mobile banking security reference model is useful in improving system security by systematically analyzing information security threats to the mobile financial service, and by presenting the guideline for the preparation of countermeasures.

• 제어로봇시스템학회논문지
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• 제7권5호
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• pp.420-426
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• 2001

In this paper, we introduce a case study of developing a miniature humanoid robot that has 16 degrees of freedom and is able to perform statically stable walking. The developed humanoid robot is 37cm tall and weighs 1,200g. RC servo motors are used as actuators. The robot can walk forward and turn to any direction on an even surface. It equipped with a small digital camera, so it can transmit vision data to a remote host computer via wireless modem. The robot can be operated in two modes: One is a remote-controlled mode, in which the robot behaves according to the command given by a human operator through the user-interface program running on a remote host computer, the other is a stand-alone mode, in which the robot behaves autonomously according the pre-programmed strategy. The user-interface program also contains a robot graphic simulator that is used to produce and verify the robot\`s gait motion. In our walking algorithm, the ankle joint is mainly used for balancing the robot. The experimental results shows that the developed robot can perform statically stable walking on an even surface.

• Tribology and Lubricants
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• 제21권2호
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• pp.71-76
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• 2005

This paper compares of mechanical tensile properties of 6 kinds of copper foil. The beam lead made with copper foil. Different from other package type such as plastic package, Chip Size Package has a reliability problem in beam lead rather than solder joint in board level. A new tensile loading system was developed using voice-coil actuator. The new tensile loading system has a load cell with maximum capacity of 20 N and a non-contact position measuring system based on the principle of capacitance micrometry with 0.1nm resolution for displacement measurement. Strain was calculated from the measured displacement using FE analysis. The comparison of mechanical properties helps designer of package to choose copper for ensuring reliability of beam lead in early stage of semiconductor development.

• 로봇학회논문지
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• 제7권4호
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• pp.284-291
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• 2012

Recently, development of underwater robot has actively been in progress in the world as ROV(Remotely Operator Vehicle) and AUV(Autonomous Unmmanded Vehicle) style. But KIOST(Korea Institute of Ocean Science and Technology), beginning in 2010, launched the R&D project to develop the robot, dubbed CRABSTER(Crab + (Lob)ster) in a bid to enhance the safety and efficiency of resource exploration. CRABSTER has been designed to be able to walk and swim with its own legs without screws. Among many research subjects regarding CRABSTER, optimal swimming patterns are handled in this paper. In previous studies, drag forces during one period with different values for angle of each joint were derived. However kinematics of real-robot and fluid-dynamics are not considered. We conducted simulations with an optimization algorithm for swimming by considering simplified fluid dynamics in this paper. Drag-coefficients applied to the simulation were approximated values calculated by CFD(Computational Fluid Dynamics : Tecplot 360, ANSYS). In addition, optimized swimming patterns were applied to a real robot. The experiments with the real robot were conducted in circumstances in the water. As a result, when the experiments were carried out in the water, a regular pattern of drag force output came out depending on the movement of the robot. We confirmed the fact that the drag forces from the simulation and the experiment has a high similarity.