• 소음진동
• /
• 제10권5호
• /
• pp.830-837
• /
• 2000

This paper deals with an analysis and countermeasure of escalator vibration. The vibration characteristics of escalators are studied theoretically and experimentally to fine the main cause of severe vibration. The main source of vibration in escalators is found to be chordal effect due to the step chain and sprocket system. It is also found that the vibration become significantly large at so called no load condition, in which the load due to passengers, during down-moving, is equal to the resistive force in the driving system. Dynamic absorbers are implemented to suppress the vibration, A theoretical analysis is made to determine the appropriate dynamic absorber. Theoretical and experimental study shows that dynamic absorber is effective to suppress the vibration in escalators.

• 한국정밀공학회지
• /
• 제12권6호
• /
• pp.105-111
• /
• 1995

The inverse dynamic equations for 5 link robot including a closed chain have been derived. The closed chain is virtually cut open, and the kinematics and dynamics of the virtual open chain robot are analyzed. The constraints are applied to the virtually cut joints by the Jacobian matrix which represents the configuration of the closed chain. The topology of tree structrued open chain robot is described by a FATHER array. The FATHER array of a link indicates the link tha tis connected in the direction of base link. Based on the inverse dynamic equations, the torque sensitivity models of the 5 link robot have been developed. The sensitivity models characterize the sensitivity of the driving torque with respect to the link parameters. All the procedures are illustrated through the 2 link robot.

• Asian Journal of Business Environment
• /
• 제2권2호
• /
• pp.35-39
• /
• 2012

Purpose - Today's world is rapidly changing due to swift changes in organization's infrastructures and supply chain is becoming an important factor which affects the organization's global competitiveness. Research design / data / methodology - Researchers indicated that environment uncertainty is considered an external driving force to establish a unique supply chain. Market competition, reducing the gap of performance and quality between the products are compelling the practitioners and researcher to change the paradigm of managing the business processes effectively and efficiently. Results - In old times, supply chain of any organization was measured on the basis of inventory turns, defect rats, lead times, stock buffering and service level. But, Lee H.L. in 2004, published an article in Harvard Business Review who proposed three A (Adaptable, Agile and Aligned) termed as "Triple-A" of successful supply chain. Conclusions - He claimed that organizations can compete through the creation of Triple-A supply chain. Hence, the basic aim of this review paper is to develop basic insights regarding what is Triple-A of supply chain, its importance and functioning in today's competitive world.

• Journal of Information Display
• /
• 제2권2호
• /
• pp.22-26
• /
• 2001

This paper presents the idea of staggered voting for the efficient TMR implementation of shift register chains for improving the yield of Poly-Si TFT-LCD driving circuits. The paper discusses the characteristic features of staggered voting and performs a quantitative evaluation of its effectiveness. Staggered voting allows us to improve the reliability of a single-voter TMR chain significantly when the probability of a voter failure is not negligible.

• 한국정보통신학회:학술대회논문집
• /
• 한국정보통신학회 2018년도 춘계학술대회
• /
• pp.205-206
• /
• 2018

최근 4차산업 혁명으로 인하여 무인 이동체, 자율주행자동차, 커넥티드 카 등에 관심이 증가하고 있고, 자율주행 능력도 올라가고 있다. 자율주행능력에 따라 최대 6단계로 나누어지며 높은 단계일수록 주행에 있어 사람의 관여가 줄어들고, 최고 단계에서는 사람이 관여하지 않아도 된다. 오늘날의 자율 주행자동차는 4~5단계까지 개발되었지만 사고 발생 시 해결방안에 대해서는 명확하게 정의되지 않아 테스트 런만 가능한 상태이다. 이처럼 이동수단 주행 중 발생되는 사고는 거의 불가피하며 사고 발생시 누가 더 잘못했는지 판단하여 사고에 대한 처벌을 가중한다. 이러한 부분을 명백히 하기 위하여 블랙박스를 사용하지만, 촬영된 영상을 삭제하기 쉬워 뺑소니와 같은 사고를 해결하는데 어려움이 있다. 본 논문에서는 이러한 사고를 해결하고자 블록체인을 활용한 주행기록 시스템을 설계하고자 한다.

• 대한안전경영과학회지
• /
• 제20권4호
• /
• pp.1-6
• /
• 2018

Recently, bicycle has means of effective healthy transportation, and riding the bicycles is considered as popular recreational and sporting activities. Also, the saddle, steering system, driving device and braking device are researched briskly because of consumer's need for driving performance and comfort. Especially, the importance of a cassette responsible for transmission function by transmitting power to the drive shaft through the chain is very focused. The writer conducted structural analysis for the sprocket of each level using the ANSYS widely used for the analysis. Speed shifting performance was enhanced by minimization / simplification of shifting point through a sort of tooth profile of the cassette. By partitioning a clear value type and other shifting point, it has been modified to enable smooth speed-shifting. In addition, as titanium precision forming process, this study studied the molding technique by blanking and dies forging for mass production of the cassette. so it could be expected that the entire drive train would utilize that in the future. The stamping process capability for thin materials for the mass production of the sprockets is applicable to producing automobile parts, so lightweight component production is likely to be possible through that, for the safety of driving.

• 로봇학회논문지
• /
• 제7권2호
• /
• pp.113-119
• /
• 2012

In this paper we propose the method that detects moving objects in autonomous navigation vehicle using LRF sensor data. Object detection and tracking methods are widely used in research area like safe-driving, safe-navigation of the autonomous vehicle. The proposed method consists of three steps: data segmentation, mobility classification and object tracking. In order to make the raw LRF sensor data to be useful, Occupancy grid is generated and the raw data is segmented according to its appearance. For classifying whether the object is moving or static, trajectory patterns are analysed. As the last step, Markov chain Monte Carlo (MCMC) method is used for tracking the object. Experimental results indicate that the proposed method can accurately detect moving objects.

• 한국지능시스템학회논문지
• /
• 제22권1호
• /
• pp.22-27
• /
• 2012

본 논문에서는 볼 나사의 구동에 의해 물체의 파지가 가능한 로봇 그리퍼 메커니즘을 제시한 후, 시뮬레이션을 통하여 제시한 그리퍼 메커니즘의 파지 동작에서 나타날 수 있는 기구학적인 특성을 분석한다. 이를 위하여 구동기의 관절 공간과 그리퍼의 끝 공간간의 기구학적 관계를 파악한다. 제안한 로봇 그리퍼는 하나의 구동모터를 사용하고, 좌우 대칭인 폐체인(closed-chain)을 형성하고 있는 것이 특징이다. 결과적으로, 제안한 로봇 그리퍼는 구조적으로 외력에 강인하고, 하나의 구동모터에 의해 파지 동작이 구현되므로 수월한 파지가 가능하다. 또한 제안된 그리퍼는 파워 파지에 유용한 조임 효과를 갖는다.

• Ocean and Polar Research
• /
• 제26권2호
• /
• pp.333-339
• /
• 2004

This paper is concerned with an experimental investigation about tractive performance of a tracked vehicle on extremely soft soil. A tracked vehicle model with principal dimensions of $0.9\;m(L)\;{\times}\;0.75\;m(B)\;{\times}\;0.4\;m(H)$ and the weight of 167 kg was constructed with a pair of driving chain links driven by two AC-servo motors. The tracks are configured with detachable grousers with variable span. Deep seabed was simulated by means of bentonite-water mixture in a soil bin of $6.0\;m(L)\;{\times}\;3.7\;m(B)\;{\times}\;0.7\;m(H)$. Slip of vehicle and driving torque of motor were measured with respect to experimental variables; grouser span, grouser chevron angle, driving speed, drawbar-pull weight, position of center-of-gravity and weight. $L_8$ orthogonal array is adopted for DOE (Design Of Experiment). The effects of experiment variables on traction performance are evaluated.

• 한국해양공학회지
• /
• 제20권4호
• /
• pp.37-42
• /
• 2006

This paper is concerned with experimental investigation of steering performance of a tracked vehicle on extremely soft soil. A tracked vehicle model with principal dimensions of 0.9 m(L)x0.75 m(B)x0.4 m(H) and weight of 167 kg was constructed with a pair of driving chain links, driven by two AC-servo motors. The tracks were configured with detachable grousers with variable span. A deep seabed was simulated by means of a bentonite-water mixture in a soil bin of 6.0 m(L)x3.7 m(B)x0.7 m(H). The turning radii of vehicle and driving torques of motors were measured with respect to experiment variables: steering ratio, driving speed, grouser chevron angle, grouser span, and grouser height. L8 orthogonal table is adopted for DOE (Design of experiment). The effects of experiment variables on steering performance are evaluated.