• Title/Summary/Keyword: 힘 반영기구

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수동 힘반영 기구의 수동성 제어

  • 김범섭;황창순;박민용;조창현;송재복
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2004.05a
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    • pp.21-21
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    • 2004
  • 본 논문은 수동 힘반영 기구의 안정성을 제어하기 위한 방법으로 수동성 제어기를 제안한다. 수동 힘반영 기구는 브레이크와 같은 수동 엑츄에이터를 사용함으로써 힘을 반영하게 되는데, 여기에 사용되는 수동 엑츄에이터는 사용자가 움직이고자 하는 방향의 반대방향으로만 힘을 생성할 수 있기 때문에, 힘을 생성할 수 있는 방향에 제한이 있다. 따라서 가상의 벽면을 나타내는 데에도 정확히 원하는 방향의 힘을 제시하지 못하고, 힘의 근사화를 통하여 가장 근접한 방향의 힘을 생성해낸다. 이는 이상적인 수동 힘반영 기구의 연구에서도 나타나며, FME(Force Manipulability Ellipsoid)에 의해 명확하게 설명이 되는 현상이다.(중략)

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Performance Analysis of Singularity-Free 3-DOF Parallel Haptic Device with Redundanct Acutation (여유구동을 지닌 무특이점 병렬형 3 자유도 햅틱기구의 성능행석)

  • Kim, Tae-Joo;Chung, Goo-Bong;Lee, Jae-Hoon;Yi, Byung-Ju;Suh, Il-Hong
    • Proceedings of the KIEE Conference
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    • 2003.07d
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    • pp.2396-2398
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    • 2003
  • 세 개의 체인으로 구성된 병렬형 3 자유도 기구는 특이점을 지님으로 인하여 햅틱기구로 활용시 불특정한 힘반영으로 인해 제한요소가 발생한다. 본 논문은 여유구동을 활용함으로써 특이점을 해소하고, 힘반영의 크기를 증가시킴으로써 햅틱기구의 성능을 향상시키는 것을 목적으로 한다. 또한 여유구동 모터를 베이스에 부착함으로써 관성력을 최소화 시키고, 와이어와 기어비를 활용하여 부드럽고 큰 힘반영 능력을 가능케 했으며, 시뮬레이션을 통해 힘반영 성능을 확인하였다.

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Development of a Hybrid Haptic Master System Without Using a Force Sensor (힘 센서를 이용하지 않는 혼합형 햅틱 마스터 시스템의 개발)

  • Park, Gi-Hwan;Bae, Byeong-Hun
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.25 no.8
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    • pp.1308-1316
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    • 2001
  • A hybrid type master system is proposed to take the advantage of the link mechanism and magnetic levitation mechanism without using a force sensor. Two different types of electromagnetic actuators, moving coil type and moving magnet types are used to drive the master system which is capable of 4-DOF actuation. It is designed that the rotation motions about x-y axis are decoupled and the whole system is represented by simple dynamic equations. The force reflection is achieved by using the simple relation between the force and applied current and position. The simulation and experimental results are presented to show its performance.

The design of the remote control Crabster robotic arm (Crabseter 로봇팔의 원격 제어기 설계)

  • Choi, Hyeung-Sik;Jeong, Sang-Ki;Uhm, Tai-Woong;Loc, Mai Ba;Kim, Joon-Young
    • Proceedings of the Korean Society of Marine Engineers Conference
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    • 2011.10a
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    • pp.77-78
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    • 2011
  • 한국해양연구원에서 개발 중인 Crabster 로봇팔을 기구학적으로 분석하고, 속도기구학을 매트랩을 이용하여 작업공간에 대해서도 분석 및 해석을 완료하였다. 운용자와 Crabster 로봇팔의 움직임을 고려해 개념 설계한 인간팔 크기의 7축 마스터 암 및 그립퍼의 기구부에 대해 2D 및 3D의 도면을 완성하였고, 마스터 암에 적용할 모터의 사양과 각 관절에 피드백 된 힘을 반영하기 위한 구동 모터의 엔코더를 이용한 위치 센서, DSP2812를 이용한 제어 명령 입력 장치와 구동 모터 드라이버를 포함한 마스터 - 슬레이브 시스템의 개념 설계를 완성하였다.

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PWR 16×16 사용후핵연료 집합체 다운엔더 개념설계

  • Kim, Yeong-Hwan;Lee, Jae-Won;Lee, Han-Su;Park, Geun-Il;Lee, Jeong-Won;Jo, Gwang-Hun
    • Proceedings of the Korean Radioactive Waste Society Conference
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    • 2012.05a
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    • pp.141-142
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    • 2012
  • 다운엔더 개념설계요건 설정을 위해서 PWR $16{\times}16$ SF집합체 제원을 분석하였다. 또한 수직에서 수평으로 전환될 때 충격량을 최소화하기 위해서 모의집합체 충격실험을 수행하였다. 그 결과 수직에서 수평으로 회전되는 각속도(30초/$90^{\circ}$)를 고려할 때 평균값은 약 0.1 g, 최대 약 0.3 g 정도가 되어 거의 충격을 받지 않음을 알 수 있다. 주요 설계요건으로 그리이드(grid)에 가해지는 수평클램프(clamp) 힘은 240kg, 하부노즐에 가해지는 수직클램프 힘은 900kg 이내로 하였다. 다운엔더의 개념설계를 위해서 기구학적 특성을 반영하였고, 전환시간을 30초/$90^{\circ}$로 하였다. 원격 유지 보수성을 향상하기 위하여 Solid Works 프로그램 툴(tool)을 이용하여 5개의 주요 모듈을 구성하였고, SF 집합체 다운엔더 개념을 3D로 설계하였다.

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선박의 속도 저하를 고려한 운항효율제고에 관한 연구

  • Gong, Gil-Yeong;Lee, Bo-Gyeong;Lee, Yun-Seok
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • 2013.06a
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    • pp.198-200
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    • 2013
  • 최근 국제해사기구(IMO)의 해양환경보호위원회에서(MEPC)는 선박에서 대기로 방출되는 CO2의 양을 최소로 하기 위해서 신조선 설계 건조시 에너지효율지수(EEDI : Energy Efficiency Design Index for new ships), 에너지 효율지표(EEOI : Energy Efficiency Operational Indicator), 그리고 에너지 효율관리 계획(SEEMP : Ship Energy Efficiency Management Plan) 지수들을 이용하여 전 세계 이산화탄소 배출 규제 방침을 운영하고 있다. 이러한 환경규제 강화와 발맞추어 세계 각국은 지속적인 Green-ship의 개발과 저탄소 고효율 선박의 운항을 위해 연구와 노력한다. 본 연구에서는 선박이 움직이는데 있어 동력이 시작되는 부분과 그 힘이 전달되어 운항자의 의식이 반영되어 선체의 이동으로 이어지기까지 흐름에 대해 도식 및 수식으로 정리하였다. 그리하여 해상의 상태와 이에 따른 운항결정이 어떤 결과를 초래할 수 있는지 살펴보고 이 부분에서 운항효율을 증대시킬 수 있는 부분에 대해 모색해 보았다. 또한 엔진의 상태에 따른 연료 절감율에 대해 살펴보고 보다 경제적 운항을 위한 적정 RPM과 속도 등에 대해서 고찰해 보았다. 이 같은 정리를 통해 앞으로의 Echo-ship, Green-ship의 연구방향에 대한 초석으로 삼고자 한다.

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Three-Dimensional Kinematic Model of the Human Knee Joint during Gait

  • Mun, Joung-Hwan;Seichi Takeuchi
    • Journal of Biomedical Engineering Research
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    • v.23 no.3
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    • pp.171-179
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    • 2002
  • It is well known that the geometry of the articular surface plays a major role in the kinematic and kinetic analysis to understand human knee joint function during motion. The functionality of the knee joint cannot be accurately modeled without considering the effects of sliding and lolling motions. We Present a 3-D human knee joint model considering sliding and rotting motion and major ligaments. We employ more realistic articular geometry using two cam profiles obtained from the extrusion of the sagittal Plain view of the representative Computerized Tomography image of the knee joint compared to the previously reported model. Our model shows good agreement with the already reported experimental results on Prediction of the lines of force through the human joint during gait. The contact point between femur and tibia moves toward the Posterior direction as the knee undergoes flexion, reflecting the coupling of anterior and Posterior motion with flexion/extension. The anterior/posterior displacement of the contact Point on the tibia plateau during one gait cycle is about 16 mm. for the lateral condyle and 25 mm. for the medial condyle using the employed model Also. the femur motion on the tibia undergoes lateral/medial movement about 7 mm. and 10 mm. during one gait cycle for the lateral condyle and medial condyle. respectively. The developed computational model maybe Potentially employed to identify the joint degeneration.

Globalization and Independency of Populist Nations' Welfare Policies: Focusing on the Influences of Multinational Pharmaceutical Companies on the Korean Government's Policy on the Pharmaceutical Industry (세계화와 국민국가의 복지정책 자율성: 다국적 제약자본이 우리나라 제약정책 결정에 미친 영향을 중심으로)

  • Lee, Su-Yun;Kim, Young-Mi
    • Korean Journal of Social Welfare
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    • v.57 no.3
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    • pp.5-30
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    • 2005
  • Globalization has conflicting effects on pharmaceutical policies. A change into a 'populist competitive nation' due to globalization strengthens policies to reduce drug manufacturing costs while the WTO's TRIPS Agreement that is affected by multinational pharmaceutical companies increases drug manufacturing costs by bolstering the patent rights on new drugs. Currently, the independency of populist nations' policies to reduce drug manufacturing cost is being compromised because multinational organizations(such as the European Union) which represents the interests of the multinational pharmaceutical companies put restrictions on the pharmaceutical policies of populist nations for purposes of promoting the industrial goals of the multinational companies. Korea is no exception. Up until the late 1990s, the main feature of the pharmaceutical policies in Korea was keeping the drug price at the cost level based on a growth-driven ideology, and this was Korea's unique policy tools as a developing nation. However, the increase in the power of multinational pharmaceutical companies currently infringes on the independency of Korea's pharmaceutical policies. Expensive imported drugs were originally covered by the national health insurance plan, but starting from 1999 such drugs began to be covered by the plan. After separation of medical and pharmaceutical services, the use of expensive drugs was increased, and the Korean government planned to introduce the reference price policy in order to contain the cost of the national health insurance plan. However, due to pressures from the U.S. government as well as multinational pharmaceutical companies, implementation of the policy has been postponed. In addition, due to a pressure from the U.S. government, a working group was created which would affect the health care policy of the Korean government. Discussions so far on globalization was about whether the change into populist competitive nations due to globalization resulted in the reduction of welfare spending. However, this study shows not only the reduction of health care cost through policies to reduce drug manufacturing costs but increase in welfare spending by raising the strengths of multinational pharmaceutical companies that are for-profit providers of welfare service. While focusing on the contradictory effects of globalization on pharmaceutical policies of a nation, this study looked at how these conflicting effects end up promoting the interests of multinational pharmaceutical companies by examining the Korean case.

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Changes in Agricultural Extension Services in Korea (한국농촌지도사업(韓國農村指導事業)의 변동(變動))

  • Fujita, Yasuki;Lee, Yong-Hwan;Kim, Sung-Soo
    • Journal of Agricultural Extension & Community Development
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    • v.7 no.1
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    • pp.155-166
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    • 2000
  • When the marcher visited Korea in fall 1994, he was shocked to see high rise apartment buildings around the capitol region including Seoul and Suwon, resulting from rising demand of housing because of urban migration followed by second and third industrial development. After 6 years in March 2000, the researcher witnessed more apartment buildings and vinyl house complexes, one of the evidences of continued economic progress in Korea. Korea had to receive the rescue finance from International Monetary Fund (IMF) because of financial crisis in 1997. However, the sign of recovery was seen in a year, and the growth rate of Gross Domestic Products (GDP) in 1999 recorded as high as 10.7 percent. During this period, the Korean government has been working on restructuring of banks, enterprises, labour and public sectors. The major directions of government were; localization, reducing administrative manpower, limiting agricultural budgets, privatization of public enterprises, integration of agricultural organization, and easing of various regulations. Thus, the power of central government shifted to local government resulting in a power increase for city mayors and county chiefs. Agricultural extension services was one of targets of government restructuring, transferred to local governments from central government. At the same time, the number of extension offices was reduced by 64 percent, extension personnel reduced by 24 percent, and extension budgets reduced. During the process of restructuring, the basic direction of extension services was set by central Rural Development Administration Personnel management, technology development and supports were transferred to provincial Rural Development Administrations, and operational responsibilities transferred to city/county governments. Agricultural extension services at the local levels changed the name to Agricultural Technology Extension Center, established under jurisdiction of city mayor or county chief. The function of technology development works were added, at the same time reducing the number of educators for agriculture and rural life. As a result of observations of rural areas and agricultural extension services at various levels, functional responsibilities of extension were not well recognized throughout the central, provincial, and local levels. Central agricultural extension services should be more concerned about effective rural development by monitoring provincial and local level extension activities more throughly. At county level extension services, it may be desirable to add a research function to reflect local agricultural technological needs. Sometimes, adding administrative tasks for extension educators may be helpful far farmers. However, tasks such as inspection and investigation should be avoided, since it may hinder the effectiveness of extension educational activities. It appeared that major contents of the agricultural extension service in Korea were focused on saving agricultural materials, developing new agricultural technology, enhancing agricultural export, increasing production and establishing market oriented farming. However these kinds of efforts may lead to non-sustainable agriculture. It would be better to put more emphasis on sustainable agriculture in the future. Agricultural extension methods in Korea may be better classified into two approaches or functions; consultation function for advanced farmers and technology transfer or educational function for small farmers. Advanced farmers were more interested in technology and management information, while small farmers were more concerned about information for farm management directions and timely diffusion of agricultural technology information. Agricultural extension service should put more emphasis on small farmer groups and active participation of farmers in these groups. Providing information and moderate advice in selecting alternatives should be the major activities for consultation for advanced farmers, while problem solving processes may be the major educational function for small farmers. Systems such as internet and e-mail should be utilized for functions of information exchange. These activities may not be an easy task for decreased numbers of extension educators along with increased administrative tasks. It may be difficult to practice a one-to-one approach However group guidance may improve the task to a certain degree.

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