• 한국자동차공학회논문집
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• 제19권1호
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• pp.17-24
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• 2011

TMED(Transmission Mounted Electric Device) parallel hybrid configuration can realize EV(Electric Vehicle) mode by disengaging the clutch between an engine and a transmission-mounted motor to improve efficiencies of low load driving and regenerative braking. In the EV mode, however, jerk can be induced since there are insufficient damping elements in the drive-train. Though the jerk gives demoralizing influence upon driving comport, adding a physical damper is not applicable due to constraints of the layout. This study suggests the jerk reduction control, composed of active damping method and torque profiling method, to suppress the jerk without hardware modification. The former method creates a virtual damper by generating absorbing torque in the opposite direction of the oscillation. The latter method reduces impulse on the mated gear teeth of the drive-train by limiting the gradient of traction torque when the direction of the torque is reversed. To validate the effectiveness of the suggested strategy, a series of vehicle tests are carried out and it is observed that the amplitude of the oscillation can be reduced by up to 83%.

• 전력전자학회논문지
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• 제5권5호
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• pp.427-434
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• 2000

본 논문은 유도전동기의 직접벡터 제어 시스템에서 전동기가 기동 시 토크 충격없이 부드럽게 기동할 수 있는 기동기법을 제시한다. 정지모드에서는 고정자 전류만으로 고정자자속을 계산하는 방식을 사용하며, 기동 후 직접 벡터제어 모드에서는 프로그램어블 3-단계 저역필터로 고정자자속을 계산한다. 정지모드에서 직접벡터제어 모드로 변환 시 3-단계 저역필터의 시간지연으로 고정자 자속이 급격히 감소되어 토크 역시 갑자기 감소된다. 본 논문에서는 전동기가 기동 시 토크 충격을 방지하기 위한 고정자 자속의 피이드포워드 제어 기법을 제시하고, 시뮬레이션 및 실험을 통하여 이 기법의 타당성을 확인한다.

• 한국운동역학회지
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• 제16권2호
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• pp.1-8
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• 2006

The purpose of this study was to evaluate normalized jerk according to shoes, slope, and velocity during walking. Eleven different test subjects used three different types of shoes (running shoes, mountain climbing boots, and elevated forefoot walking shoes) at various walking speeds(1.19, 1.25, 1.33, 1.56, 1.78, 1.9, 2, 2.11, 2.33m/sec) and gradients(0, 3, 6, 10 degrees) on a treadmill. Since there were concerns about using the elevated forefoot shoes on an incline, these shoes were not used on a gradient. Motion Analysis (Motion Analysis Corp. Santa Rosa, CA USA) was conducted with four Falcon high speed digital motion capture cameras. Utilizing the maximum smoothness theory, it was hypothesized that there would be differences in jerk according to shoe type, velocity, and slope. Furthermore, it was assumed that running shoes would have the lowest values for normalized jerk because subjects were most accustomed to wearing these shoes. The results demonstrated that elevated forefoot walking shoes had lowest value for normalized jerk at heel. In contrast, elevated forefoot walking shoes had greater normalized jerk at the center of mass at most walking speeds. For most gradients and walking speeds, hiking boots had smaller medio-lateral directional normalized jerk at ankle than running shoes. These results alluded to an inverse ratio for jerk at the heel and at the COM for all types of shoes. Furthermore, as velocity increased, medio-lateral jerk was reduced for all gradients in both hiking boots and running shoes. Due to the fragility of the ankle joint, elevated forefoot walking shoes could be recommended for walking on flat surfaces because they minimize instability at the heel. Although the elevated forefoot walking shoes have the highest levels of jerk at the COM, the structure of the pelvis and spine allows for greater compensatory movement than the ankle. This movement at the COM might even have a beneficial effect of activating the muscles in the back and abdomen more than other shoes. On inclines hiking boots would be recommended over running shoes because hiking boots demonstrated more medio-lateral stability on a gradient than running shoes. These results also demonstrate the usefulness of normalized jerk theory in analyzing the relationship between the body and shoes, walking velocity, and movement up a slope.

• 한국운동역학회지
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• 제19권4호
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• pp.739-748
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• 2009

본 연구의 목적은 2008년 베이징올림픽 남자 역도 금메달리스트인 사재혁선수를 대상으로 최대의 노력으로 경기력을 수행하고 있는 실제 경기상황에서 동일한 중량으로 Jerk동작의 1차시기 실패 후 2차시기 성공을 운동학적으로 분석하여 실패의 원인을 구명하여 사재혁 선수의 Jerk기술 향상과 경기력을 극대화시키고 현장에서 선수들을 지도하는데 필요한 기초자료를 제공하는데 있었다. 본 연구를 수행한 결과 다음과 같은 결론을 얻었다. 성공 동작이 실패동작에 비하여 1국면에서는 짧은 시간을, 3국면과 4국면에서는 다소 긴 수행시간을 보였다. 바벨의 수직변화는 큰 차이를 보이지는 않았으나, 무릎에서는 E4에서 실패 시 낮은 수직 위치를 나타냈다. 바벨의 수직속도는 4국면에서 무릎의 수직속도는 3국면과 4국면에서 성공과 실패동작 간에 큰 차이를 보였다. 3국면의 실패동작에서 성공동작에 비하여 빠른 신체무게중심의 하방속도가 나타났다. E3순간의 실패동작에서 성공동작에 비하여 더 굴곡된 무릎각도가 나타났다.

• 한국운동역학회지
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• 제17권1호
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• pp.185-190
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• 2007

The purpose of this study was to investigate the effects that breathing, thoracic and abdominal, had on the smoothness while performing ballet pour de bra. Five skilled ballet dancers(age: $24{\pm}1$, height: $163.4{\pm}2.88$, weight: $44.4{\pm}1.34$) with experience of over 10 years participated in this study. Each participant performed the ballet movement three times with abdominal respiration and with thoracic respiration. The kinematic data was recorded at 60 Hz with three digital cameras (Sony VX-2100). The pour de bra movement consists of two phases, up and down. The up phase is defined as the movement from the en bas through the en avant to the en haut. The down phase is defined as the movement from the en haut through the $\grave{a}$ la seconde to the en bas. During these two phases the Jerk Cost (JC) factor was calculated for the shoulder, elbow and wrist to quantify the smoothness. The group who performed the movement while abdominal respiration had a lower JC factor and so it was concluded that while abdominal respiration the smoothness of the movement was increased as opposed to the thoracic respiration.

• 한국안전학회지
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• 제32권3호
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• pp.117-122
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• 2017

In this study, we studied the ride quality considering the deterioration effects of the three type couplers (single, double, and ring types) for EMUs. In order to know the impact occurred when an urban transit vehicle is under breaking, we tested the conditions of the service brake and the emergency brake. Normal coupler models without any slack showed similar dynamic performance results under all breaking conditions. But if the couplers become old, the initial pre-stresses are removed because of permanent compressive deformation in rubber. For three types of the old coupler models without the initial pre-stress, we evaluated dynamic performances of each type. As the results, the maximum and average acceleration levels of the double type and the ring type were similarly low in all conditions. But the accelerations of the single type coupler was high when compared to those of the double and ring types. In addition, Jerk value of the single type model associated with ride quality was high up to 15 times to the ring type in condition of the service braking in empty vehicle weight. Jerk value of the double type model was high up to 6 times to the ring type.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 추계학술대회 논문집
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• pp.1132-1137
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• 2008

Automatic Operation based on ATO (Automatic Train Operation) is necessary for driverless Light Rail Transit business. When this kind of driverless LRT operation plan is made, TPS (Train Performance Simulation) is traditionally simulated at all-out mode and coasting mode based on manual operation. Commercial schedule speed equals to all-out speed minus $9{\sim}15%$ make-up margin. Coasting mode TPS simulation is also run at commercial schedule speed to calculate run time and energy consumption. But TPS based on manual operation should make an improvement on accuracy in case of driverless LRT operation Plan. In this paper, new fast mode TPS simulation using ATO pattern is proposed and show near actual ATO result. The actual ATO pattern can be accurately simulated with the introduction of 4 parameters such as commercial braking rate, jerk, station stop profile and grade converted distance. Normal mode TPS simulation for commercial schedule speed can be designed to have fast mode trip time plus 3 seconds/km margin recommended by korean standard LRT specification.

• 대한산업공학회지
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• 제9권2호
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• pp.9-25
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• 1983

The purpose of this study was to film up computerized analyses for both kinematic posture(film analysis) and muscle dynamics (EMG) during a weight-lifting motion. (Snatch, Clean and Jerk) Using a motor drive camera (3.5 frames/sec) and a Location Analyzer, motion tracks of 13 landmarks, which were attached to the major joints, during the motion were converted into digital values. At the same time, EMG amplitudes from 11 major muscle groups were recorded. Recorded data were processed via analog/hybrid computer (ADAC 480) and digital computer (PDP 11/44). Landmark locations and EMG amplitude were integrated by a computerized routine. Computer output included graphic reproductions on sepuential dislocations of body segments, center of gravity of body segments and the associated changes on EMG amplitude such as % EMG's of major muscle group during a weight lifting motion. The results strongly suggest that the computerized motion-EMG integration can provide a further working knowledge in selection and in training of workers and athletes. Suggestions for a further study include additional device for velocity measurement, expansion of the link model for biomechanical analysis and other implementations necessary for athletic application.

• 대한정형외과스포츠의학회지
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• 제1권1호
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• pp.26-30
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• 2002

목적: 동종골-슬개건-골을이용한전방십자인대재건술시인간골간섭나사못의초기및조기고정력을알아보려고하였다. 대상및방법 : 동종골-슬개건-골을이용한전방십자인대재건술을28 슬관절에대해수술후6주, 12주, 6개월, 1년에추적조사하였다. Lachman test, flexion rotation drawer test, jerk test등의이학적검사를시행하였고KT-1000 측정을동시에시행하여경골의전방전위정도를측정하였다. Lachman test는 0$\~$2mm 전방전위까지를정상으로하였고KT-1000 측정은정상측과비교하여 2mm 이내는정상으로하였다. 마지막검사시M RI를시행하였다. 결과: 단일예를제외하고는모두이학적검사와KT-1000 측정상정상범위에속하였다. 실패한일례는수술소견상이식물이경골터널에서의근위전위되었으며이는넓어진터널을감안하지않고단하나의간섭나사못을사용한기술적실수로평가되었다. 결론: 인간골골피간섭나사못은전방십자인대의재건술을시행하는데충분한초기및조기고정력을보여주었다.