• 제어로봇시스템학회논문지
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• 제4권3호
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• pp.360-371
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• 1998

In this paper, output precision characteristics of a planar 6 degree-of-freedom parallel mechanisms are investigated, where the 6 degree-of-freedom mechanism is formed by adding an additional link along with an actuated joint in each serial subchain of the planar 3 degree-of-freedom parallel mechanism. Kinematic analysis for the parallel mechanism is performed, and its first-order kinematic characteristics are examined via kinematic isotropic index, maximum and minimum input-output velocity transmission ratios of the mechanisms. Based on this analysis, two types of planar 6 degrees-of-freedom parallel manipulators are selected. Then, dynamic characteristics of the two selected planar 6 degree-of-freedom parallel mechanisms, via Frobenius norms of inertia matrix and power modeling array, are investigated to compare the magnitudes of required control efforts of both three large actuators and three small actuators when the link lengths of three additional links are changed. It can be concluded from the analysis results that each of these two planar 6 degrees-of-freedom parallel mechanisms has an excellent control-in-the-small characteristics and therefore, it can be very effectively employed as a high-precision macro-micro manipulator when both its link lengths and locations of small and large actuators are properly chosen.

• 원예과학기술지
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• 제34권6호
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• pp.940-958
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• 2016

The objective of this study was to analyze the kinematic and kinetic characteristics of two horticultural activities: seed sowing and planting plant. Thirty-one male university students (aged $26.2{\pm}2.0years$) participated in this study. Kinematic factors (movement times, peak velocity, joint angles, and grasp patterns) were assessed using a three-dimensional motion analysis system while the subjects performed the horticultural activities. Kinetic factors (muscle activation of eight upper-limb muscles: the anterior deltoid, serratus anterior, upper trapezius, infraspinatus, latissimus dorsi, biceps brachii, brachioradialis, and flexor carpi radialis) were assessed using surface electromyography. The acts of seed sowing and planting plant were comprised of five tasks which included six types of phases: reaching, grasping, back transporting, forward transporting, watering, and releasing. The movement times, peak velocity, joint angles, and grasp patterns were significantly different across the tasks involved in the horticultural activities. All eight muscles of the upper limbs were utilized during the horticultural activities, and the muscle activation of the serratus anterior was the highest compared to that of the other muscles tested. The kinematic and kinetic characteristics of these horticultural activities showed similar characteristics to reaching and grasping rehabilitation training and daily living activities. The present study provides reference data for common horticultural activities using a kinematic and kinetic analysis.

• 말소리와 음성과학
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• 제15권1호
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• pp.19-24
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• 2023

This study investigated acoustic (VOT) and articulatory characteristics of Korean velar stops in monosyllabic CV structures to examine how the three-way distinction is realized in the laryngeal and supralaryngeal domains and how the distinction is manifested in male versus female speakers' speech production. EMA data were collected from 22 speakers. In line with previous studies, male speakers preserved the three-way differentiation of velar stops (/k^*/</k/</k^h/) in terms of VOT while female speakers showed only a two-way distinction (/k^*/</k/=/k^h/). As for the kinematic characteristics, a clear three-way distinction was found only in male speakers' peak velocity measure in the C-to-V opening movement (/k^h/</k/</k^*/). For the other kinematic measures (i.e., articulatory closure duration, deceleration duration of the opening movement and the entire opening movement duration), male speakers showed only a two-way distinction between fortis and the other two stops. Female speakers did not show a three-way contrast in any kinematic measure. They showed a two-way distinction between lenis and the other two stops in C-to-V deceleration duration (/k^*/=/k^h/</k/), and a two-way distinction between fortis and lenis stops in the opening movement duration. An overall comparison of VOT and articulatory analyses revealed that the lenis-aspirated kinematic distinction is diminishing, driven by female speakers, in line with the loss of the lenis-aspirated distinction in VOT that could influence supralaryngeal articulation.

• International Journal of Automotive Technology
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• 제6권4호
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• pp.403-411
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• 2005

The bus is regarded as one of the most frequently used public transportation systems, the research and development on driving stability, safety, and convenience for drivers and passengers has tremendously increased in recent days. This paper investigated the design of the bus door mechanism composed of an actuator (or motor) and linkages. The bus door mechanism is divided into many types according to the coupling of the linkages and the driving system. The mathematical models of all types of door mechanism have been constructed for computer simulation. To design the bus door mechanism, we developed a simulation program, which automates the kinematic and dynamic analysis according to the input parameters of each linkage and the driving system. Using this program, we investigated the design parameters that affect the kinematic and dynamic characteristics of the bus door mechanism under various simulation conditions. In addition, simple examples are examined to validate the developed program.

• 로봇학회논문지
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• 제6권1호
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• pp.78-85
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• 2011

This article investigates kinematic characteristics of a Sch$\ddot{o}$nflies motion generator which represents a mechanism having translational three Degree-of-Freedom (DOF) and rotational one-DOF motion about a fixed axis. The mechanism consists of the base plate and the moving plate, and four identical limbs connecting them. Each limb employs two revolute joints (RR), one parallelogram (Pa), and two revolute joints (RR) from the base plate to the moving plate. The mechanism is driven by four actuators which are placed on the base plate to minimize dynamic loads. It is shown through simulations that the mechanism can be designed to secure large dexterous workspace and thus has very high potential for actual applications such as haptic devices and high-speed requiring tasks such as pick-and-place operations, riveting, screwing tasks, etc.

• 대한기계학회논문집A
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• 제28권7호
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• pp.904-914
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• 2004

In this paper, input-output velocity and force transmission characteristics of the Casing Oscillator which is a construction machine with 4 degrees of freedom are examined. After the Jacobian matrix is decomposed into the linear part and angular part, the velocity and force transmission characteristics for the linear and angular workspace are easily analyzed and visualized even if the Casing Oscillator has the spatial dimensional workspace with 4 DOF. Regarding the manipulability measure of the Casing Oscillator, the kinematic isotropic index and the manipulability measure which represent the isotropy and volume of the manipulability ellipsoid, respectively, are combined to coincidently consider them with respect to equivalent ranges and fluctuations. A performance of the Casing Oscillator is evaluated by the newly proposed manipulability measures.

• 한국정밀공학회지
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• 제28권8호
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• pp.878-885
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• 2011

A kinematically-hybrid 5-axis machine tool is analyzed from the perspective of machine tool design. Its kinematic characteristics are pointed out, which should be considered during the conceptual design process. A result of the structural analysis of the machine is presented, which is performed during the detailed design process. It is also presented how we improve the thermal characteristics of the machine tool by changing the installation position of the actuators.

• 한국산학기술학회논문지
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• 제18권3호
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• pp.306-311
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• 2017

본 논문은 자동차 현가장치의 기구적 특성에 대한 설계 최적화에 관한 것이다. 현가장치의 기구적 특성은 토우 및 캠버와 같은 바퀴의 자세를 결정하며 이것은 주행 중 타이어의 마모에 관련될 뿐만 아니라 차량의 운동성능인 조종안정성에 큰 영향을 미친다. 따라서 설계 초기단계에서 현가장치 기구의 특성을 결정하는 것은 매우 중요한 일이다. 본 논문에서는 맥퍼슨 스트러트식 현가장치에 대한 현가장치의 기구적 특성을 파악하기 위하여 변위해석을 수행하였다. 이를 위해 현가장치 기구를 구성하는 조인트에 대한 구속방정식을 세우고 이를 풀 수 있는 프로그램을 작성하였다. 또한 원하고자 하는 현가장치의 기구적 특성을 얻기 위하여 설계 최적화 프로그램인 ADS를 이용하였다. 최적화를 위한 설계변수로서 현가장치의 차체 부착점인 하드 포인트의 좌표로 설정하였으며 목표함수로서 바퀴의 상하운동에 대한 토우-인의 합으로 정의하였다. 구속함수로서 설계 시 제한조건인 최대 캠버각과 최저 롤 중심고를 고려하였다. 본 연구의 결과로서 두 가지 구속함수를 만족하고 토우-인의 변화를 최소로 하는 하드 포인트의 최적위치를 결정할 수 있었다.

• 한국물환경학회지
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• 제23권1호
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• pp.38-45
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• 2007

A one-dimensional kinematic wave model was used to calculate temporal and spatial changes of the highway runoff. Infiltration into pavement was considered using Darcy's law, as a function of flow depth and pavement hydraulic conductivity ($K_p$). The model equation was calculated using the method of characteristics (MOC), which provided stable solutions for the model equation. 22 storm events monitored in a highway runoff monitoring site in west Los Angeles in the U.S. were used for the model calculation and evaluation. Using three different values of $K_p$ ($5{\times}10^{-6}$, $10^{-5}$, and $2{\times}10^{-5}cm/sec$), total runoff volume and peak flow rate were calculated and then compared with the measured data for each storm event. According to the calculation results, $10^{-5}cm/sec$ was considered a site representative value of $K_p$. The study suggested a one-dimensional method to predict hydrodynamic behavior of highway runoff, which is required for the water quality prediction.

• 한국운동역학회지
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• 제15권4호
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• pp.75-83
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• 2005

The purpose of this study was to determine the kinematic characteristics of the ankle joint and RPM(repetition per minutes) during the supra maximal training in cycling. For this study, 8 national representative cyclists, distance cyclists in track and road, were selected. During the super-maximum pedalling, kinematic data were collected using a six-camera(240Hz) Qualisys system. the room coordinate system was right-handed and fixed in the back of a roller for cycle, with right-handed orthogonal segment coordinate systems defined for the leg and foot. Lateral kinematic data were recorded at least for 3 minutes while the participants pedal on a roller. Two-dimensional Cartesian coordinates for each marker were determined at the time of recording using a nonlinear transformation technique. Coordinate data were low-pass filtered using a fourth-order Butterworth recursive filter with cutoff frequency of 15Hz. Variables analyzed in this study were compared using a one factor(time) ANOVA with repeated measures. The results of investigation suggest that the number of rotating pedal was decreased with time phase during the super-maximum pedaling. Maximum angle of the ankle joint showed little in change with time phase compared with minimum angle of that.