• 제목/요약/키워드: Contact Theory

검색결과 518건 처리시간 0.022초

창업교육연계의 효과측정모형 및 정책제안 (Effects of Entrepreneurship Education Based on Relative Policies Link)

  • 설병문
    • 벤처창업연구
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    • 제7권2호
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    • pp.9-17
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    • 2012
  • 다양한 유형의 공공기관과 교육기관에서 창업지원사업을 시행 중이다. 본 연구는 창업교육을 중심으로 각 기관과 단체에서 실행하고 있는 창업지원사업을 연계함으로써 지원성과 제고효과가 있음을 제시한다. 창업지원사업의 목적을 달성하기 위해서 요구되는 것은 창업이전단계부터 창업초기를 거쳐 죽음의 계곡이라 불리는 시점을 극복한 후 성장기업으로 안정화 되는 기간까지, 전체과정에 대한 일관되면서도 효과적인 지원이다. 현재까지 이루어진 대부분 선행연구에서 창업교육 후 사후관리의 필요성을 제시하고 있다. 그러나 교육 후 사후관리의 현실적 방안제시에는 한계를 보이고 있다. 이러한 한계점은 창업교육을 창업전과정의 한 부분으로 분리해서 접근하는 인식에서 발생한다. 이와 같이 분리된 접근 방식은 창업과 관련된 다양한 지원정책의 현실적인 공통점으로 보인다. 본 연구는 창업교육과 창업관련 지원의 연계에서 발생하는 기대효과를 제시하고, 지원정책들과 창업교육의 연계방안으로 창업인증제도의 필요성을 제기한다.

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Design and Experimental Evaluation of a Robust Force Controller for a 6-Link Electro-Hydraulic Manipulator via H$_{\infty}$ Control Theory

  • Ahn, Kyoung-Kwan;Lee, Byung-Ryong;Yang, Soon-Yong
    • Journal of Mechanical Science and Technology
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    • 제17권7호
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    • pp.999-1010
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    • 2003
  • Uninterrupted power supply has become indispensable during the maintenance task of active electric power lines as a result of today's highly information-oriented society and increasing demand of electric utilities. This maintenance task has the risk of electric shock and the danger of falling from high place. Therefore it is necessary to realize an autonomous robot system using electro-hydraulic manipulators because hydraulic manipulators have the advantage of electric insulation and power/mass density. Meanwhile an electro-hydraulic manipulator using hydraulic actuators has many nonlinear elements, and its parameter fluctuations are greater than those of an electrically driven manipulator. So it is relatively difficult to realize not only stable contact work but also accurate force control for the autonomous assembly tasks using hydraulic manipulators. In this paper, the robust force control of a 6-link electro-hydraulic manipulator system used in the real maintenance task of active electric lines is examined in detail. A nominal model for the system is obtained from experimental frequency responses of the system, and the deviation of the manipulator system from the nominal model is derived by a multiplicative uncertainty. Robust disturbance observers for force control are designed using this information in an H$\_$$\infty$/ framework, and implemented on the two different setups. Experimental results show that highly robust force tracking by a 6-link electro-hydraulic manipulator could be achieved even if the stiffness of environment and the shape of wall change.

봉 추나요법의 개요 (Introduction of Bong Chuna Manual Therapy)

  • 오원교;신병철
    • 척추신경추나의학회지
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    • 제2권1호
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    • pp.99-114
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    • 2007
  • Objectives : The purpose of this study was to introduce the Chuna Manual Therapy (CMT) using Bong (a type of stick which is called 'bong') as a part of Oriental Medicine. Methods : We searched several traditional methods of CMT using Bong, either individual contact to specialist of CMT using Bong or referred to publications, and summarized briefly for introduction. Authors also made a comparative study between existing CMT and CMT using the bong. Results & Conclusions : The indications of Bong CMT are regarded as acute or chronic pain syndrome, whiplash associated disorders, facet syndrome, vertebral misalignment, chronic fatigue syndrome, obesity and also lower extremity length difference caused by malalignment of vertebrae and pelvic bone. The Meridian Muscle Therapy by pressing down using the Bong can be carried out on the imbalances of the muscle by shortening and lengthening contraction. CMT with Bong is considered more effective than other existing CMT in terms of effectiveness. In the case of pelvic correction which needs a tremendous amount of force, it can reduce the force required effectively. This fact can be inferred by the theory of composition and decomposition of force during the transmission of power. We can perform Bong CMT feeling less fatigued subsequently than general CMT. Pressing down with flexed fingers to grip bong acts on the contraction of flexor digiti and extensor digiti muscle, this protects the $doctor^{\circ}{\emptyset}s$ wrist joints from injury. The bong which acts as a tool between the doctor and the patient, while being given treatment, absorbs and spreads out the direct impact from the patient to the doctor. CMT with Bong is able to apply to both existing massage therapies with the hand. The bong appliance can be used in all applications, particularly, but not limited to; Orthopedic and Manual Correction Therapy, Meridian Muscle Pressing, Exercise Therapy, and Meridian Point Manual Pressing Therapy. CMT with Bong belongs to the category of oriental rehabilitation and Chuna manual medicine.

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광감도 비교를 통한 면외 변형 측정 조건에 대한 연구 (Study on the Out-of-Plane Deformation Measurement Condition through Comparison Photosensitivity)

  • 김현호;강찬근;이현준;정현철;김경석;홍정기
    • 한국정밀공학회지
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    • 제32권9호
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    • pp.807-813
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    • 2015
  • In the present study, an interferometer system, which integrates the laser sensitivity control technique based on the theory of electronic speckle pattern interferometry, one of non-contact non-destructive analysis methods, was developed. This interferometry system receives an image from CCD cameras for each reference and object, and compares the photosensitivity of the object and reference images from imagification. For the purpose of this study, the photosensitivity of object and reference light is measured with power meters, and the amount of light was controlled with an ND filter with a reference light port matching photosensitivity. Using the plate specimen as the object, 0.6, 0.9, 1.2, and $1.5{\mu}m$ of out-plane deformation was made, and images were compared according to the difference in photosensitivity. After analysis, larger object deformations showed larger numbers of stripe patterns. Images became clearer and data error was reduced when the photosensitivity of object and reference light matched.

수직 진동을 이용한 가열된 고체표면 위 증발하는 액적의 내부유동 제어연구 (Study of the Internal Flow and Evaporation Characteristic Inside a Water Droplet on a Vertical Vibrating Hydrophobic Surface)

  • 박창석;임희창
    • 대한기계학회논문집B
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    • 제41권1호
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    • pp.37-46
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    • 2017
  • 가열된 표면에서의 액적은 일반적으로 내부에 마랑고니 유동이 발생하고, 이는 불균일한 침전물 패턴 형상을 구성하게 된다. 본 연구는 마랑고니 유동을 가시화하고, 수직진동을 사용해서 이를 제어하는 것을 주 목적으로 한다. 액적이 증발하는 동안, 액적의 접촉각 변화와 부피변화를 실험적으로 알 수 있었고, PIV(Particle Image Velocimetry) 실험 장치를 이용하여, 평판 온도별 마랑고니 유동의 내부 유동의 흐름을 가시화하였다. 그리고 평판에 각 주파수별 수직진동을 가해주는 실험을 진행하여, 그 결과 마랑고니 유동의 유동 방향과 수직진동의 유동 방향이 서로 반대인 것을 확인할 수 있었다. 마지막으로 증발하는 액적에 수직진동을 가해줌으로써, 액적의 하단부분에서 내부유동의 흐름변화를 관찰하였다. 마랑고니유동에 의해 발생하는 내부유동 방향과 수직진동으로 발생하는 내부유동의 방향이 서로 반대 방향이므로 가열된 평판에 진동을 가해주었을 때 액적 내부유동의 흐름이 변화가 발생하였고, 이는 곧 불균일한 침전물 패턴이 억제된 것을 증발 후 침전물의 패턴형상을 통해 확인할 수 있었다.

An inclined FGM beam under a moving mass considering Coriolis and centrifugal accelerations

  • Shokouhifard, Vahid;Mohebpour, Saeedreza;Malekzadeh, Parviz;Alighanbari, Hekmat
    • Steel and Composite Structures
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    • 제35권1호
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    • pp.61-76
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    • 2020
  • In this paper, the dynamic behaviour of an inclined functionally graded material (FGM) beam with different boundary conditions under a moving mass is investigated based on the first-order shear deformation theory (FSDT). The material properties vary continuously along the beam thickness based on the power-law distribution. The system of motion equations is derived by using Hamilton's principle. The finite element method (FEM) is adopted to develop a general solution procedure. The moving mass is considered on the top surface of the beam instead of supposing it on the mid-plane. In order to consider the Coriolis, centrifugal accelerations and the friction force, the contact force method is used. Moreover, the effects of boundary conditions, the moving mass velocity and various material distributions are studied. For verification of the present results, a comparative fundamental frequency analysis of an FGM beam is conducted and the dynamic transverse displacements of the homogeneous and FGM beams traversed by a moving mass are compared with those in the existing literature. There is a good accord in all compared cases. In this study for the first time in dynamic analysis of the inclined FGM beams, the Coriolis and centrifugal accelerations of the moving mass are taken into account, and it is observed that these accelerations can be ignored for the low-speeds of the moving mass. The new provided results for dynamics of the inclined FGM beams traversed by a moving mass can be significant for the scientific and engineering community in the area of FGM structures.

사용자-서브루틴과 양해법 유한 요소 해석을 이용한 선박의 유빙 저항 추정 (Ice Floe-induced Ship Resistances using Explicit Finite Element Analyses with a User-subroutine)

  • 한동화;백광준;정성엽;정준모
    • 대한조선학회논문집
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    • 제57권2호
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    • pp.88-95
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    • 2020
  • There have been many attempts to predict resistance of vessels in ice floe environment, but they mostly have both strong and weak points at the same time; for instance, simplified formulas are very fast but less flexible to types of ship and ice conditions and other numerical techniques need high computing cost for increased accuracy. A new numerical simulation technique of combining explicit finite element analysis code with a user-subroutine to control real-time forces acting on ice floes was proposed, thereby it was possible to predict ship-to-ice floe resistance with higher convenience and accuracy than other proposed approaches. The basic theory on how real-time hydrostatic and hydrodynamic forces acting on ice floes could be generated using user-subroutine was explained. The heave motion of a single ice floe was simulated using the user-subroutine and the motion amplitudes and periods were almost consistent with analytic values. Towing tests of an icebreaker model ship were simulated using explicit finite element analyses with the user-subroutine. The ice-induced resistance obtained from the towing experiments and simulations showed significant differences. Intentional increase of the drag coefficient to increase the contact duration between the ice floes and rigid model ship leaded the total resistance to be substantially consistent between the model tests and numerical simulations.

지역간(地域間) 학력고사(學力考査)와 지능(知能)에 대(對)한 비교연구(比較硏究) -대학학력고사(大學學力考査)를 중심(中心)으로- (A Comparative Study on the Relation between the Scholastic Achievement Test and the Intelligence according to the Area - Centering around the Scholastic Achievement Test of University -)

  • 류희영;김정화
    • 동의신경정신과학회지
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    • 제1권1호
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    • pp.81-93
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    • 1990
  • On the Scholastic Achievement Test grads it was compared Chung Nam's with Cheon Puk by dividing a city, a farm village, a fishing village and a mountine village. The results were as follows ; 1. The regional difference of arerage grades were that the first is a large city, the second amiddle city, the third a mountine villgae, the fourth a fishing village, the last a farm village all the same Chung Nam and Cheon Puk. 2. The grades of acity and a farm of Chung Nam are higher then these of Cheon Puk. 3. Cheon Puk is higher than Chung Nam on a middle city, a mountine and a fishing's grades. 4. The characteristic was that the region of non benefits of civilization effect obstruction of intelligence less than a city mountine village. 5. It is considered that the obstruction of intelligence may diminish when eating marine products at a fishing village than a city-fishing village by side dish. From the above results, acknowledging a regional charater, it is suggested that improrement of food life imitate city shund sublate lest the physiological function of Bie Wee(脾胃) should converse a puthological state, get out of the food life civilization misled abnormal food life to normal. Systemic study must continue for maintaining of tradition of regional difference food life. By that manner excellent food life civilization may creat. Therefore it is recognized that experience accumulation of Oriental Medicine theory also close contact food life, so may make constent effort.

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레이저스펙클 간섭법과 4단계 위상이동법에 의한 외팔보 점용접부의 면외 변위측정 (Measurement of Out-of-plane Displacement in a Spot Welded Canti-levered Plate using Laser Speckle Interferometry with 4-step Phase Shifting Technique)

  • 백태현;김명수;나의균;고승기
    • 한국정밀공학회지
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    • 제19권3호
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    • pp.66-72
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    • 2002
  • Electronic Speckle Pattern Interferometry (ESPI) has been recently developed and widely used because it has advantage to be able to measure surface deformations of engineering components and materials in industrial areas with non-contact. The speckle patterns to be formed with interference and scattering phenomena can measure not only out-of-plane but also in-plane deformations, together with the use of digital image equipment to process the informations included in the speckle patterns and to display consequent interferogram on a computer monitor. In this study, the experimental results of a canti-levered plate using ESPI were compared with those obtained from the simple beam theory. The ESPI results of the canti-levered plate analyzed by 4-step phase shifting method are close to the theoretical expectation. Also, out-of-plane displacements of a spot welded cacti-levered plate were measured by ESPI with 4-step phase shifting technique. The phase map of the spot welded cacti-levered plate is quite different from that of the canti-levered plate without spot welding.

압력손실시험을 이용한 막 완결성 평가에서 초기압력 및 UCL 도출인자 민감도 분석 (Sensitivity Analysis of Initial Pressure and Upper Control Limit on the Pressure Decay Test for Membrane Integrity Evaluation)

  • 이주희;홍승관;허현철;이광제;최영준
    • 한국물환경학회지
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    • 제24권6호
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    • pp.793-800
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    • 2008
  • Recently domestic drinking water industry has recognized membrane-based technology as a promising alternative for water treatment. To ensure successful application of membrane processes, the integrity of membrane systems should be maintained. According to US EPA guidance, the pressure decay test based on the bubble point theory is recommended to detect any membrane defection of which size is close to the smallest diameter of Cryptosporidium oocysts, $3{\mu}m$. Proper implementation of the pressure decay test is greatly affected by initial test pressure, and the interpretation of the test results is associated with upper control limit. This study is conducted to investigate various factors affecting determination of initial test prtessure and upper control limit, including membrane-based parameters such as pore shape correction factor, surface tension and contact angle, and system-based parameters, such as volumetric concentration factor and total volume of system. In this paper, three different hollow fibers were used to perform the pressure decay test. With identical initial test pressure applied, their pressure decay tendency were different from each other. This finding can be explained by the micro-structure disparity of those membranes which is verified by FESEM images of those membranes. More specifically, FESEM images revealed that three hollow fibers have asymmetry, deep finger, shallow finger pore shape, respectively. In addition, sensitivity analysis was conducted on five parameters mentioned above to elucidate their relation to determination of initial test pressure and upper control limit. In case of initial pressure calculation, the pore shape correction factor has the highest value of sensitivity. For upper control limit determination, system factors have greater impact compared to membrane-based parameters.