• 한국산업정보학회논문지
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• 제17권2호
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• pp.19-27
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• 2012

In railway tunnel environment, the reliability of a high-data-rate and real-time train-to-wayside communication should be maintained especially when high-speed train moves along the track. In China and Europe, the communication frequency around 900 MHz is widely used for railway applications. At this carrier frequency band, both of the solutions based on continuously laid leaky coaxial cable (LCX) and discretely installed base-station antennas (BSAs), are applied in tunnel radio coverage. Many available works have concentrated on the radio-wave propagation in tunnels by different kinds of prediction models. Most of them solve this problem as natural propagation in a relatively large hollow waveguide, by neglecting the transmitting/receiving (Tx/Rx) components. However, within such confined areas like railway tunnels especially loaded with train, the complex communication environment becomes an important factor that would affect the quality of the signal transmission. This paper will apply a full-wave numerical method to this case, for considering the BSA or LCX, train antennas and their interacted environments, such as the locomotive body, overhead line for power supply, locomotive pantograph, steel rails, ballastless track, tunnel walls, etc.. Involving finite-difference time-domain (FDTD) method and uni-axial anisotropic perfectly matched layer (UPML) technique, the entire wireless RF downlinks of BSA and LCX to tunnel space to train antenna are precisely modeled (so-called integrative modeling technique, IMT). When exciting the BSA and LCX separately, the field distributions of some cross-sections in a rectangular tunnel are presented. It can be found that the influence of the locomotive body and other tunnel environments is very significant. The field coverage on the locomotive roof plane where the train antennas mounted, seems more homogenous when the side-laying position of the BSA or LCX is much higher. Also, much smoother field coverage solution is achieved by choosing LCX for its characteristic of more homogenous electromagnetic wave radiation.

• Transactions on Control, Automation and Systems Engineering
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• 제2권4호
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• pp.285-297
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• 2000

One of the research objectives in the area of multimedia human-computer interaction is the application of artificial intelligence and robotics technologies to the development of computer interfaces. This involves utilizing many forms of media, integrating speed input, natural language, graphics, hand pointing gestures, and other methods for interactive dialogues. Although current human-computer communication methods include computer keyboards, mice, and other traditional devices, the two basic ways by which people communicate with each other are voice and gesture. This paper reports on research focusing on the development of an intelligent multimedia interface system modeled based on the manner in which people communicate. This work explores the interaction between humans and computers based only on the processing of speech(Work uttered by the person) and processing of images(hand pointing gestures). The purpose of the interface is to control a pan/tilt camera to point it to a location specified by the user through utterance of words and pointing of the hand, The systems utilizes another stationary camera to capture images of the users hand and a microphone to capture the users words. Upon processing of the images and sounds, the systems responds by pointing the camera. Initially, the interface uses hand pointing to locate the general position which user is referring to and then the interface uses voice command provided by user to fine-the location, and change the zooming of the camera, if requested. The image of the location is captured by the pan/tilt camera and sent to a color TV monitor to be displayed. This type of system has applications in tele-conferencing and other rmote operations, where the system must respond to users command, in a manner similar to how the user would communicate with another person. The advantage of this approach is the elimination of the traditional input devices that the user must utilize in order to control a pan/tillt camera, replacing them with more "natural" means of interaction. A number of experiments were performed to evaluate the interface system with respect to its accuracy, efficiency, reliability, and limitation.

• 센서학회지
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• 제20권3호
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• pp.213-218
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• 2011

The load cell is a force sensor and a transducer that is used to convert a physical force into a electrical signal for weighing equipment. Most conventional load cells are widely used a metal foil strain gauge for sensing element when force being applied spring element in order to converts the deformation to electrical signals. The sensitivity of a load cell is limited by its low gauge factor, hysteresis and creep. But silicon-based sensors perform with higher reliability. This paper presents the basic design and development of the silicon type load cell with an SUS630 diaphragm. The load cell consists of two parts the silicon strain gauge and the SUS630 structure with diaphragm. Structure analysis of load cell was researched by theory to optimize the load cell diaphragm design and to determine the position of peizoresistors on a silicon strain gauge. The piezo-resistors are integrated in the four points of silicon strain gauge processed by ion implantation. The thickness of the silicon strain gauge was polished by CMP under 100 ${\mu}M$. The 10 mm diameter SUS630 diaphragm was designed for loads up to 10 kg with 300 ${\mu}M$ of diaphragm thickness. The load cell was successfully tested, the variation of ${\Delta}$R(%) of four points on the silicon strain gauge is good linearity properties and sensitivity.

• 한국융합학회논문지
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• 제9권10호
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• pp.457-465
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• 2018

본 연구는 간호사의 병원근무환경과 상사와의 신뢰도를 파악하고 그에 따른 이직의도에 미치는 영향을 알아보기 위한 서술적 조사연구이다. 대상자는 B시에 소재한 5개의 병원에 재직 중인 간호사 122명으로 설문지를 통해 자료를 수집하였고, 수집된 자료는 SPSS 22.0 프로그램으로 이용하여 분석하였다. 연구결과, 병원근무환경과 이직의도(r=.534, p<.001)는 정적인 상관관계가 있었고, 병원근무환경과 상사와의 신뢰도(r=-.232, p=.010) 및 상사와의 신뢰도와 이직의도(r=-.314, p<.001)는 부적인 상관관계가 있었다. 간호사의 이직의도에 영향을 주는 요인은 병원근무환경(${\beta}=.505$, p<.001), 상사와의 신뢰도(${\beta}=-.229$, p=.003), 직위(${\beta}=-.213$, p=.011)로 나타났다. 따라서 간호사의 이직의도를 줄이기 위해서 병원근무환경을 개선하고, 상사와의 신뢰 형성과 향상을 위한 전략적 프로그램 마련이 필요하다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 심포지엄 논문집 정보 및 제어부문
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• pp.377-379
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• 2007

To reduce the chattering errors of reed switch sensors used for automatic remote measurement of water supply system, a reed switch sensor was analyzed and improved. The operation of reed switch sensors can be described as a mechanical contact by approximation of permanent magnet piece to generate an electrical pulse. The reed switch sensors are used in measurement application by detecting the rotational or translational displacement. To apply for flow measurement devices, the reed switch sensors should keep high reliability. They are applied for the electronic digital type of water flow meters. The reed switch sensor is just installed simply on the mechanical type flow meter. A small magnet is attached on a pointer of the water meter counter rotor. Inside the reed sensor, two steel leaf springs make mechanical contact and apart as rotation of flow meter counter. The counting electrical contact pulses can be converted as the water flow amount. The MCU sends the digital flow rate data to the server using the wireless communication network. But it occurs data difference or errors by chattering noise. The reed switch sensor contains chattering error by it self at the force equivalent position. The vibrations such as passing car near to the switch sensor installed location. In order to reduce chattering error, most system uses just software methods for example using filter and also statistical calibration methods. The chattering errors were reduced by changing leaf spring structure using mechanical hysteresis characteristics.

• 한국콘텐츠학회논문지
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• 제16권7호
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• pp.398-409
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• 2016

본 연구의 목적은 노인요양시설에 기업의 경영방식 중 하나인 지식경영을 접목해 지식경영의 요인인 인적 자산과 구조적 자산이 조직성과에 미치는 영향을 분석하고자 한다. 충청남북도 소재의 노인요양시설 종사자 229명을 연구대상으로 하였으며, 수집된 자료는 SPSS 21.0프로그램을 이용하여 빈도분석, 기술분석, 신뢰도 검증, 상관관계, 회귀분석을 실시하였다. 분석 결과, 구조적 자산의 하위요소인 공유문화와 프로세스의 영향력이 높았고 나이, 직위, 운영주체가 조직성과에 유의미한 영향을 미치는 것으로 나타났다. 그러나 인적 자산의 영향력은 유의미하지 않았다. 즉, 프로세스 수준이 높고, 공유문화가 발달되고, 나이와 직위가 높을수록, 개인보다 의료와 종교 법인이 운영할수록 조직성과가 높음을 알 수 있다. 본 연구결과는 노인요양시설의 조직성과를 높이기 위해서는 공유문화를 높이기 위한 조직 간의 적극적 지식공유에 대한 협조가 필요하고, 기관은 프로세스 수준을 높이기 위해 다양한 프로그램을 개발, 구성원들이 자유롭게 대화할 수 있는 환경을 조성할 필요가 있음을 보여주고 있다.

• 비파괴검사학회지
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• 제30권4호
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• pp.295-301
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• 2010

원자력발전소 탄소강 배관의 유체가속부식은 주요 경년열화 현상이며 발전소의 성능 및 안전성을 저해할 수 있다. 유체가속부식 검사는 보온재 제거 및 설치로 상당한 비용이 수반되므로 최근에 보온재 제거가 필요 없고 원거리 검사가 가능한 유도초음파에 대한 관심이 점점 증가되고 있다. 유체가속부식 검출에 유도초음파 적용이 가능하다면 검사 비용 절감이 예상된다. 본 연구의 목적은 유체가속부식 손상 유무를 확인하고 결함 검출능을 결정하기 위함이다. 본 연구에서는, 실제 유체가속부식 손상 시험편의 엘보우 첫 번째 용접부와 두 번째 용접부의 진폭 감쇄비를 측정하기 위하여 3가지 검사 기법을 사용하였다. 연구 결과, 유체가속부식 손상을 검출하기 위한 최적의 검사 기법과 최소 결함 검출능을 도출하였다.

• 로봇학회논문지
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• 제11권4호
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• pp.262-269
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• 2016

Flight of an autonomous unmanned aerial vehicle (UAV) generally consists of four steps; take-off, ascent, descent, and finally landing. Among them, autonomous landing is a challenging task due to high risks and reliability problem. In case the landing site where the UAV is supposed to land is moving or oscillating, the situation becomes more unpredictable and it is far more difficult than landing on a stationary site. For these reasons, the accurate and precise control is required for an autonomous landing system of a UAV on top of a moving vehicle which is rolling or oscillating while moving. In this paper, a vision-only based landing algorithm using dynamic gimbal control is proposed. The conventional camera systems which are applied to the previous studies are fixed as downward facing or forward facing. The main disadvantage of these system is a narrow field of view (FOV). By controlling the gimbal to track the target dynamically, this problem can be ameliorated. Furthermore, the system helps the UAV follow the target faster than using only a fixed camera. With the artificial tag on a landing pad, the relative position and orientation of the UAV are acquired, and those estimated poses are used for gimbal control and UAV control for safe and stable landing on a moving vehicle. The outdoor experimental results show that this vision-based algorithm performs fairly well and can be applied to real situations.

• 센서학회지
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• 제11권1호
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• pp.39-47
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• 2002

광 저장장치는 디스크 트랙에 레이저빔을 위치시켜 정보를 저장한다. 정보의 용량이 증대되면서 좀더 높은 저장 밀도를 요구하게 되었고, 그만큼 정밀한 레이저빔의 위치제어가 필요하게 되었다. 본 논문에서는 광 저장장치용 정전형 마이크로 미러를 MEMS기술을 이용해 제조하고 그 특성을 조사하였다. 마이크로 미러는 벌크 마이크로머시닝 기술에 의하여 제조되었으며, 특히 접합공정이 이루어지고 난 후에 연마공정에 의해서 실리콘 웨이퍼의 두께 및 미러면의 형태를 형성하는 공정을 적용함으로서 제현성을 높였다. 제작된 미러의 크기는 $3.0mm{\times}2.5mm$ 이고, 35V에서 변위는 $3.2{\mu}m$ 였다.

• International Journal of Aeronautical and Space Sciences
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• 제16권1호
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• pp.1-7
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• 2015

In order to provide some references for suitability of carrier-based aircrafts, this paper studies the flow field of exhaust jets and its impact on the flight deck. The geometrical models of aircraft carrier and carrier-based aircrafts are firstly built, on which unstructured tetrahedral meshes are generated for numerical analysis. Then, this paper simulates the flow field of exhaust jets to evaluate its impact on the Jet Blast Deflector (JBD) and the flight deck, when four carrier-based aircrafts are ready to start off in the bow. The standard k-${\varepsilon}$ equations, three-dimension N-S equations and the Computational Fluid Dynamics (CFD) theory are used in the analysis process. To solve the equations, the thermal coupling of the wind and the jet flow are also considered. The velocity and temperature distributions are provided with the simulation of the CFD software, FLUENT. The results indicate that: (1) this analytical method can be used to simulate aerodynamic problems with complex geometrical models, and the results are of high reliability; (2) the safety working area, the installation scheme of the JBD and the arrangement of the take-off position can be optimized through analysis.