• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 B
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• pp.608-610
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• 2001

In this paper, 6/4 Switched Reluctance Motor(SRM) which has simple structure and little switching element is selected basic analysis model. In order to reduce torque ripple causing noise and vibration, we execute optimization of geometric parameters (stator and rotor pole arc) and electrical parameters (turn-on angle and turn-of angle) by means of combining Fletcher-Reeves's Conjugate Directions and Finite Element Method (FEM) considering driving circuits. When considering the switching condition according to inductance profile, torque characteristics is influenced by geometric and electrical parameters importantly. The pole arc and switching angle of the optimum can also obtain the low torque ripple without high currents.

• 소성∙가공
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• 제25권1호
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• pp.29-35
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• 2016

In the current study, finite element analysis was conducted for the press hemming of automotive panels in order to predict various hemming defects such as roll-in and turn down. The analysis used the exact punch movement based on the cam location and considered the sealer between the inner and outer panels with an artificial contact thickness. The analysis results quantify the hemming defects especially at the flange edge in the matching region of the head lamp. A design of experiments along with the parameter study was used to obtain the optimum process parameters for minimizing hemming defects. The optimization process selects the intake angle, bending angle of the hemming punch, and the flange height of the outer panel. The optimum design process determines an appropriate tool angle and flange height to reduce the roll-in and turn-down as compared to the initial design.

• 한국도로학회논문집
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• 제15권4호
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• pp.135-146
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• 2013

PURPOSES : This study aimed to analyze the impact the operation of pre-signals at 4-leg signalized intersections and present primary environmental factors of roads that need to be considered in the installation of pre-signals. METHODS : Shift of proportions safety effectiveness evaluation method which assesses shifts in proportions of target collision types to determine safety effectiveness was applied to analyze traffic crash by types. Also, Empirical Bayes before/after safety effectiveness evaluation method was adapted to analyze the impact pre-signal installation. Negative binomial regression was conducted to determine SPF(safety performance function). RESULTS : Pre-signals are effective in reducing the number of head on, right angle and sideswipe collisions and both the total number of personal injury crashes and severe crashes. Also, it is deemed that each factor used as an independent variable for the SPF model has strong correlation with the total number of personal injury crashes and severe crashes, and impacts general traffic crashes as a whole. CONCLUSIONS: This study suggests the following should be considered in pre-signal installation on intersections. 1) U-turns allowed in the front and rear 2) A high number of roads that connect to the intersection 3) Many right-turn traffic flows 4) Crosswalks installed in the front and rear 5) Insufficient left-turn lanes compared to left-turn traffic flows or no left-turn-only lane.

• 한국항공우주학회지
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• 제48권11호
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• pp.881-888
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• 2020

본 논문에서는 관측자가 얻을 수 있는 시선각(LOS) 측정값을 사용하여 관심표적의 상태변수를 추정하는 연구를 수행하였다. 관심상태변수는 표적의 위치, 속도 및 가속도로 설정하였다. 시선각 측정값은 필터에 표적운동모델 적용을 어렵게 하는 비선형성이 강한 측정값이다. 이러한 문제해결을 위해 가측정치 공식(Pseudomeasurement equation)을 사용하여 시선각 측정값 수식을 변경한 후 3D 가변선회(3D Variable Turn) 표적운동모델을 적용하였다. 또한 필터의 성능을 위해 기구학적구속조건(Kinematic Constraint)을 적용하였다. 필터는 초기조건에 강건한 특성을 가진 Bias Compensation Pseudomeasurement Filter (BCPMF)를 사용하였다. 병렬 계산의 이점을 위해 Two Stage Kalman Filter 형태를 추가적으로 적용하였다. 이 기법들을 사용하여 TBCPMF 3DVT-KC 필터를 제안하였고 시뮬레이션을 통해 성능을 확인하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 B
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• pp.720-722
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• 2003

This paper Presents a design schemes to minimize torque ripple in 6/4 Switched Reluctance Motor (SRM) using transient Finite Element Analysis (FEA) in which the magnetic field is combined with a driving circuit. Pole arcs and switching angles are major design factors. If these design factors are considered independently, the enhancement of SRM Performance is restricted. Therefore, this paper proposes not only optimal combination of stator pole arc and rotor pole arc but also the turn-on and turn-off angles as a function of pole arcs. Especially, turn-on and turn-off angle are formulated from a voltage equation and feasible design ranges are suggested with variable speed.

• 생명과학회지
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• 제30권4호
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• pp.321-330
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• 2020

본 연구의 목표는 CuCl₂가 지브라피시에 미치는 영향을 조사하는 것이다. CuCl₂에 대한 지브라피시의 반수치사농도를 조사하기 위하여 각기 다른 시간에 따른 농도를 설정하여 노출시켰다. 본 연구에서는 스트레스 반응의 증가를 보기 위하여 whole-body cortisol level 측정과 행동약리학적 변화를 측정하기 위해서 open field test와 novel tank test를 실시하였다. Whole-body cortisol의 sample을 수집하거나 행동실험을 실시하기 전에 CuCl₂ 또는 vehicle을 1시간 동안 처리하였다. CuCl₂의 반수치사농도는 24시간, 48시간, 96시간에서 각각 30.3, 25.3, 14.8 ㎍/l으로 측정되었다. CuCl₂에 노출된 지브라피시의 novel tank test의 결과는 총 이동거리, 움직이는 시간 그리고 속도는 유의성이 있게 감소한 반면, turn angle은 최고농도에서 유의성이 있게 증가하였다(p<0.05). 다른 행동실험인 open field test의 결과에서도 총 이동거리, 움직이는 시간 속도가 CuCl₂의 노출에 의해서 감소하였으며, turn angle과 meandering이 유의하게 증가하였다(p<0.05). CuCl₂에 노출된 지브라피시의 whole-body cortisol은 1.5 or 15 ㎍/l의 농도에서는 유의하게 증가하였으나, 150 ㎍/l의 농도에서는 유의성 있는 변화를 발견하지 못하였다(p<0.05). 본 연구의 결과는 CuCl₂의 노출이 지브라피시에서 치사율 증가, 행동 및 내분비의 변화 등을 포함하는 독성 반응을 야기하는 것을 나타낸다.

• 한국운동역학회지
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• 제22권2호
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• pp.173-181
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• 2012

The purpose of this study was to research on the movement of Fouette A La Second which was a type of turning movements on cheerleading. This research was conducted for helping cheerleaders to improve their overall skills. The three cheerleading national team members were participated in this research and the movements of Fouette A La Second were recorded with 6 digital motion master 60 video cameras, operating at a sampling frequency of 60 fields/sec. Six out of ten turning motion data were collected and analyzed with Kwon3D XP. The results were as follow: 1) The subject A's Releve motion was not executed precisely because of the COG's unstability. So she was required to improve the balancing ability. 2) The subject B could not execute the precise A La Second motion because of subject B's large hip angle. By tracing the projection of B's right toe on x-y plane, the subject made an elliptical orbit. Because B did not have a proper turning skills she needed to improve the muscle power and flexibility. She also needed to move quickly from Releve to Plie movement. 3) The subject C could not execute the Plie movement precisely, so she could not turn her body correctly around a certain spot. The subject C needed to decrease the knee angle at the Plie motion.

• 드라이브 ㆍ 컨트롤
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• 제20권4호
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• pp.9-16
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• 2023

This paper analyzed a drainage tower used to drain water in flooded areas. Multi-body dynamics simulation was used to analyze the dynamic behavior of the drainage tower. Structural analysis, flexible-body dynamic analysis, and rigid body dynamic analysis were done to study the maximum Von-Mises stress of the drainage tower. The results showed that the maximum Von-Mises stress occurs at the turn table, and it decreases when the angle of the boom is increased. Also, the rate of the change of angle affects the maximum stress so that the maximum stress changes more when the angular velocity of the boom increases. Based on the rigid body dynamic analysis and the theoretical analysis results, the centrifugal force from the angular velocity makes the difference in the maximum stress at the turn table because of the difference in their direction. Consequently, it was concluded that the centrifugal force should be considered when designing construction machinerythat can rotate.

• 수산해양기술연구
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• 제56권2호
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• pp.172-182
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• 2020

In order to offer specific information needed to assist in operation of a ship with same type rudder through evaluating the maneuverability of training ship A-Ra with flapped rudder, sea trials based full scale for turning test, zig-zag test with rudder angle 10° and 20°, and spiral test at service condition were carried out on starboard and port sides around Jeju Island according to the standards of maneuverability of IMO. As a result, the angular velocity of port turn was higher than that of starboard turn. Therefore, the size of turning circle was longer on the starboard side. In addition, variation of the transfer due to various factors was more stable than those of the others. In the Z-test results, the mean of 1st and 2nd overshoot angles were 9.8°, 6.3° and 15.3°, 9.2° respectively when the port and starboard was 10°; the 1st overshoot angle were 18°, 13.7° when using 20°. Her maneuverability index T' and K' can be easily determined by using a computer with the data obtained from Z-test where K' and T' are dimensionless constants representing turning ability and responsiveness to the helm, respectively. In the Z-test under flap rudder angle 10°, the obtained K' value covered the range of 2.37-2.87 and T' was 1.74-3.45. Under the flap rudder angle 20°, K' and T' value showed 1.43-1.63, 1.0-1.73, respectively. In the spiral test, the loop width was unstable at +0.3° and -0.5°-0.9° around the midship of flap rudder. As a result, course stability was comparatively good. From the sea trial results, training ship ARA met the present criterion in the standards of maneuverability of IMO.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 A
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• pp.321-324
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• 1995

Switched reluctance motors and drives are increasingly used in high speed applications due to their robust mechanical structures, low inertia, and reduction in the rotor losses. The turn-on angle has to be advanced as the motor speed increases, but it may cause the starting problem in some rotor positions. In this paper, the characteristics of the maximum speed and input voltage with the advance angle at high speeds is investigated. To overcome the starting problem and reduce the torque ripple, conduction overlapping is added in adjacent phases. The effectiveness of conduction overlapping is verified through the simulation and experiments.