• 제어로봇시스템학회논문지
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• 제8권10호
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• pp.881-889
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• 2002

Mobility analysis for various mobile mechanisms including mechanisms with lack of geometric generality is performed. Joint screws are employed to find the sire of feasible joint motion space or each of independent loops of mobile mechanisms. Particularly, the concept of "representative screws" is introduced to represent the feasible motion spaces for subsets of joints belonging to either a loop or a sub-system consisting of several closed loops. Firstly. simplified joint model for each of low different typical wheels popularly employed in mobile robots is described. Then. mobility analysis fir various types of planar mobile robots and the Mars Rover mobile robot for navigation on the rocky road on Mars arc performed. It is confirmed that the obtained results in this study coincide with the previous ones which were obtained by suing imaginary Joints approach(1)pproach(1)

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2002년도 ICCAS
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• pp.117.5-117
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• 2002

. Mobility analysis for overconstrained mechanisms is not clearly explained. . Aims at mobility analysis of overconstrained mechanisms . Representative screws is employed as a tool . A method to identifying the representative screw is introduced . Mobility analysis for several overconstrained parallel mechanisms and mobile robots

• Journal of Advanced Marine Engineering and Technology
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• 제36권7호
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• pp.894-901
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• 2012

For more efficient use of the high pressure water-jet in rehabilitation of the water pipes, we have studied the water-jet cleaning motion of the in-pipe robot with screw drive. The mathematical models of the water-jet in the straight and the curved pipe (90 degrees elbow), representative features of the water mains, were designed to understand the water-jet motion and simulations have been performed. Furthermore the experiments has been conducted to validate the simulations by using the prototype in-pipe robot in the 3-D pipeline. The simulation results show that the water-jet motion in the straight pipe has a constant water-jet interval, whereas the motion in the curved pipe is changed by its position. By the comparison of the simulation and the experimental results, we have demonstrated that the simulations successfully estimate the water-jet motion inside the water pipes. Therefore in-pipe robot operators can predict a water-jet motion for a target water pipe through the simulation and flexibly make a proper water-jet motion by changing the robot configurations before a cleaning work.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제28권4호
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• pp.249-255
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• 2002

Recently, Skeletal Anchorage System (SAS) has been focused clinically with the view point that it could provide the absolute intraoral anchorage. First, it began to be used for the patient of orthognathic surgery who had difficulty in taking intermaxillary fixation due to multiple loss of teeth. And then, its uses have been extended to many cases, the control of bone segments after orthognathic surgery, stable anchorage in orthodontic treatment, and anchorage for temporary prosthesis and so on. SAS has been developed as dental implants technique has been developed and also called in several names; mini-screw anchorage, micro-screw anchorage, mini-implant anchorage, micro-implant anchorage (MIA), and orthosystem implant etc. Now many clinicians use SAS, but the anatomical knowledges for the installed depth of intraosseous screws are totally dependent on general experiences. So we try to study for the cortical thickness of maxilla and mandible in Korean adults without any pathologic conditions with the use of Computed Tomography at the representative sites for the screw installation.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.1527-1532
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• 2008

45% of the sports accidents is the knee damage and the representative case is the damage of an Anterior Cruciate Ligament (ACL) and the Posterior Cruciate Ligament(PCL). Although the past different views of ACL reconstruction comes to an agreement, the disputes of PCL is remained yet. The most important engineering approach for these various surgery techniques is accurately to understand and to evaluate the fatigue behavior depending on the stress flow and the stress distribution under the allotted load and the cyclic load, which are caused by the graft fixing device, the proximal tibia of the PCL reconstructing structure. Therefore, this study is the basic research of these above facts. The current transtibial tunnel surgery using the cadaveric Achilles tendon grafts is chosen for the various PCL reconstruction. The relationships between the slippage, the extension ratio, and the slippage ratio by the heel bone fixing method and the soft tissue fixing method of the Achilles tendon were also defined. This research will be the essential data to help the resonable operating techniques for the next PCL reconstruction.

• 한국과학교육학회지
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• 제34권8호
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• pp.719-730
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• 2014

이 연구의 목적은 초등학생의 과학, 공학, 기술에 대한 인식과 과학자, 공학자, 기술자에 대한 이미지를 조사하는 데 있다. 본 연구에서는 조사도구로 Fralick et al. (2009)의 연구에서 사용된 DAST(Draw a scientist test)를 Draw a scientist at work와 Draw a engineer at work를 수정하고 변형하여 사용하였으며, 경남 G시의 S초등학교 6학년 209명을 대상으로 조사하였다. 연구 결과에 의하면, 초등학생들이 가지고 있는 과학자의 이미지는 선행연구에서 나타난 전형적인 과학자의 이미지와 비슷하였다. 공학자의 대표적인 이미지는 짧은 머리에 안경을 쓰고 있지 않으며 평상복을 입고 일을 하고 있는 형태이다. 그리고 주로 선박, 로봇, 컴퓨터, 비행기를 설계하거나 만드는 모습을 나타내었다. 기술자의 대표적인 이미지는 짧은 머리에 보호 장갑을 끼고 용접용 마스크를 착용하였다. 기술자는 자동차, 로봇 등을 고치거나 렌치, 드라이버, 용접기 등을 이용하여 일하는 모습을 나타내었다. 학생들은 공학과 기술을 학문으로 인식하지 못하는 경향을 나타냈다. 또한, 공학, 기술의 연구 분야, 연구 방법에 대해서도 다양하게 인식하지 못하였다.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제31권6호
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• pp.461-468
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• 2009

Purpose: Platelet derived growth factor(PDGF)-BB and bone morphogenetic protein(BMP)-2 are well-known representative growth factors. The purposes of this study were to investigate the effect of rhPDGFBB and rhBMP-2 on osseointegration of titanium implants at periimplant bone defects grafted with hydroxyapatite and to evaluate the feasibility of imaging bone structures around screw-type titanium implant with micro-CT. Materials and Methods: The first molar and all premolars in the mandible region of four beagle dogs were extracted. Following a healing period of 4 months, three $8{\times}8{\times}6mm$-sized bony defects were formed and screw-type titanium implants were placed with hydroxyapatite(HA) block and growth factors; Control group, PDGF group and BMP group. Two months post-implantation, the mandible was harvested. Bone volume(BV), bone-to-implant contact(BIC) and bone mineral density(BMD) were analyzed with micro-CT and histology. Results: According to micro-CT analysis, BV and BMD measures of PDGF and BMP group were significantly higher than control group(BV; PDGF group: $p{\fallingdotseq}0.011$, BMP group: $p{\fallingdotseq}0.006$/BMD; PDGF group: $p{\fallingdotseq}0.020$, BMP group: $p{\fallingdotseq}0.011$) and BIC measures of BMP group were significantly higher than PDGF group($p{\fallingdotseq}0.015$). In histologic evaluation, BIC measures of BMP group was significantly higher than PDGF group($p{\fallingdotseq}0.048$). The values of BV in histologic sections were higher than in micro-CT images and the values of BIC in micro-CT images were higher than in histologic sections. Conclusion: The findings of this experimental study indicates that the use of rhPDGF-BB and rhBMP-2 can increase new bone formation in a large bony defect around titanium implant, and rhBMP-2 is more effective than rhPDGF-BB. Micro-CT can be considered useful for assessment as a rapid and nondestructive method for 3-dimensional measurement of bone healing around implants. Further study is necessary, however, to remove metal artifacts around titanium implant and to standardize the method.

• Composites Research
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• 제34권3호
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• pp.186-191
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• 2021

요추에 퇴행이 발생하였을 때 이를 치료하기 위해 요추 유합술이 시행된다. 유합술은 척추체 사이의 추간판을 제거하고 뼈 그래프트 등을 삽입하여 굳혀 하나 이상의 분절을 완전히 고정시켜 척추의 안정성을 복원한다. 둘 이상의 척추체가 단단히 유합될 수 있게끔 척추체를 고정하는 수단으로 척추경 나사못과 연결봉이 환자의 체내에 삽입된다. 본 연구에서는 중증 요추 퇴행성 질환의 치료에 쓰이는 척추 유합술에서 사용하는 척추경 나사못 구조물이 적용된 총 7개의 환자 맞춤형 요추 유한 요소 모델을 생성하였다. 생성한 모델에 각각 티타늄과 CFR-PEEK로 구성된 연결봉을 구성하였다. 척추의 4가지 대표적 거동에 대해 유한요소해석과 통계적 분석을 진행하여 연결봉의 재질이 척추 상태에 미치는 의공학적 영향을 조사하였다. 인접 분절의 추간판 내 압력과 각 분절의 관절 구동 범위가 의공학적 영향을 확인하기 위한 지표로 사용되었다. 연결봉에 CFR-PEEK를 사용한 경우 Ti 연결봉에 비해 인접 분절의 추간판 내 압력은 감소하였고 각 분절의 관절 구동 범위는 증가하였다. 그러나 모든 하중조건에서 통계학적으로 유의미한 경향성 차이는 관찰되지 않았다.

• 한국컴퓨터정보학회논문지
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• 제27권3호
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• pp.239-249
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• 2022

이 연구는 국내 및 해외의 스쿠버다이빙리조트 활성화 요인을 도출하고 비교 분석하는데 목적이 있다. 국내와 해외 스쿠버다이빙리조트의 경영대표, 교육팀장 등 운영에 관련된 전문가 30명을 대상으로 3차례에 델파이 조사를 진행하였다. 국내와 해외의 활성화 요인을 비교 분석한 결과 공공다이빙 장소의 편의시설 확충, 다이버들을 위한 안전시설 및 의료시설 설치, AED, 산소 등 응급처치 시스템 구축, 다이빙 보트 내 입·출수 리프트, 화장실 등 편의시설 필요, 다이빙 보트 스크루 안전망 설치, 지역 보트 운항 가이드 라인, 스쿠버다이빙 정규 코스 교육 프로그램, 전문 스쿠버다이빙 강사 및 가이드 고용, 다양한 SNS를 이용한 소통 및 홍보, 다이버의 입소문을 통한 홍보, 지역 다이빙 리조트 연합회 활동, 한인 다이빙 연합회 활동, 지역 어촌계와의 소통 및 상생 정책, 지역 관광산업과 연계정책이 공통적인 중요 활성화 요인으로 나타났다.