• 한국기계기술학회지
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• 제13권4호
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• pp.157-164
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• 2011

Hybrid car can improve fuel efficiency using a power of motor that is generated during constant-speed or deceleration driving. The motor is located between engine and transmission. But, when voltage of main battery is low, fuel efficiency is low because the voltage can't run the motor. In this situation, this study observed fuel efficiency when using solar cell for assistance power. In order to verify a fuel consumption of hybrid car equipped solar cell for assistance power, the car was tested downtown driving. As hybrid car was equipped solar cell for assistance, fuel consumption was reduced 8.35 % at running air conditioner. And, at air conditioner doesn't work, fuel consumption was reduced 6.88 %. This point of view, CO2 is expected to reduce in similar proportion.

• 한국운동역학회지
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• 제16권1호
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• pp.89-99
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• 2006

The study were to assess technical factors between the high score group and the low score group, from the subjects of 16 male national gymnasts, and to analyze the kinematical characteristic and main technical cause on technique of Akopian's 3D motion analysis of the male vaulting game in 2001 classification championship. The result of this study is this. There were not so much difference between the two groups in term; of the time of board contact, pre-flight, and total performance, but it takes shorter time when the players who are in the high point group take down the board, and they take long time for post-flight(p<.01). The high point group has a longer perpendicular distance in the moment of horse taking off, 0.05m on the average, than the low point group. The high point group shows 0.16m higher on the average than the other group in term; of the height of post-flight(p<.01). In the phase of board contact, the range of horizontal velocity at board take on were $7.66m/s{\sim}7.33m/s$, but there weren't significantly statistic differences between two groups. The hight score group were 0.68m/s faster than the low point group at the horizontal velocity at board take off event(<.05). About the average horizontal velocity of deceleration, AG1(-1.95m/s) reduces the speed more than AG2(-1.57m/s)(p<.05). And the hight score group were 0.37m/s faster than the low point group at the vertical velocity at horse take off event(<.05). When board taking off, the projectile angle of com were $38.7{\sim}37.8degree$ on the average. the comparative groups show almost same results. When horse taking off, the HPVy of the high point group were 37.6 degree which were a little higher than the low point group. The angular velocities of the players who takes on the horse with a right hand and then takes off with a left hand in the high point group were 14.97rad/sec, 10.82rad/sec in the low point group. However, the angular velocity of the players who takes on the horse with a left hand and then takes off on a right hand with the high point group were 14.97rad/sec, 15.56rad/sec in the low point group.

• 대한교통학회지
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• 제31권1호
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• pp.3-13
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• 2013

본 연구는 신호기 위치 조정이 도시지역의 교차로 신호등에 접근하는 운전자들의 운전행태에 미치는 영향을 분석하여 딜레마 존의 특성을 분석하였다. 접근속도의 분석은 신호등의 위치 조정이 이루어진 3개 지점에서 측정된 사전-사후 비교를 통해 이루어졌다. 본 연구에서는 황색신호시 정지차량의 경우 지점속도를 낮춰, 딜레마존 시작점을 앞당김으로써 딜레마존의 크기를 작게 하는 반면에 통과차량의 경우 교차로에 근접하여 지점속도를 높임으로써 딜레마존 끝점을 뒤로 이동시키게 됨을 발견하였다. 결국 신호기 위치조정은 딜레마존의 크기를 줄임으로써 교차로 안전성을 증진하는 데 기여한다고 볼 수 있다. 동일한 속도로 진입한 차량군의 운행특성을 볼 때, 감속을 하기 위한 감속도가 반영되어 지점별 속도가 상당히 크게 변화했는데 이것은 딜레마존에서 사용되는 접근속도의 개념에 대한 보다 엄밀한 규정이 필요하며, 일반적으로 사용되는 접근속도의 개념이 접근구간속도임을 고려할 때 딜레마존의 계산식은 접근속도 보다 지점속도를 사용하는 것이 더 정확할 수 있음을 보여준다.

• International Journal of Fluid Machinery and Systems
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• 제2권1호
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• pp.80-91
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• 2009

In this study, a prediction theory for specific noise that is the overall characteristic of the fan has been proposed. This theory is based on total pressure prediction and broadband noise prediction. The specific noises of two forward curved fans with different number of blades were predicted. The flow around the impeller having 120 blades (MF120) was more biased at a certain positions than the impeller with 40 blades (MF40). An effective domain of the energy conversion of MF40 has extended overall than MF120. The total pressure was affected by the slip factor and pressure loss caused by the vortex flow. The suppression of a major pressure drop by the vortex flow and expansion of the effective domain for energy conversion contributed to an increase in the total pressure of MF40 at the design point. The position of maximum relative velocity was different for each fan. The relative velocity of MF120 was less than that of MF40 due to the deviation angle. The specific noise of MF120 was 2.7 dB less than that of MF40 due to the difference in internal flow. It has been quantitatively estimated that the deceleration in the relative velocity contributed to the improvement in the overall performance.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.179-181
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• 2003

Conventional P/PI speed controller of today's servo drives should be manually tuned the controller switching set-point by trial-and-errors, which may translate the drive system down-time and loss of productivity. The adjustable drive performance is heavily dependent on the qualify of the expert knowledge and becomes inadequate in applications where the operating conditions change in a wide range, i.e., tracking command, cceleration/deceleration time, and load disturbances. In this paper, the demands on simple controls/setup are discussed for industry servo drives. Analyzing the frequency content of motor torque command, P/PI control mode switching is automatically peformed with some prior knowledge of the mechanical dynamics. The dynamic performance of the proposed scheme assures a desired tracking response curve with minimal oscillation and settling time over the whole operating conditions. For comprehensive comparison of traditional P/PI control scheme, extensive test is carried out on actual servo system.

• 한국자동차공학회논문집
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• 제15권5호
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• pp.174-179
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• 2007

The transient brake time or distance is one of very important factors to guess the vehicle speed to inspect an automobile accident. But, it is usual that the vehicle speed is estimated by using only skid mark without considering the transient brake distance. Deceleration and the friction coefficients of tire and road surface play an important role in calculating the brake distance. In this paper, a scheme is presented to estimate more accurate automobile speed. The scheme contains the effect of the transient brake distance on the speed. Experiment was carried out on the asphalt, unpacked road to get relationships between the speeds and the skid mark distances, and to get the transient brake time. The experimental results were utilized to construct the equation to approximate more realistic vehicle speeds.

• 융합신호처리학회논문지
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• 제13권3호
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• pp.162-165
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• 2012

본 논문에서는 차량의 흐름을 지체시키는 병목 지점에서 차량의 연료소비 감소를 위한 WAVE 방식 기반 V2V 및 V2I 의 정보 통신 기술을 이용하여 차량의 상대적인 속도를 제어하는 방법을 제안하였다. 연비 효율 비교 분석을 위한 모델을 제시하여 주기적으로 차량의 정차를 요하는 교통 신호등 방식보다 제안하는 방식이 병목 지점에서 연비 효율이 높아짐을 보였다. 또한 이 방식에서 병목지점에 진입하는 차량 간 속도 제어를 위한 감 가속도 유도 알고리즘을 제시하였다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2017년도 제48회 춘계학술대회논문집
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• pp.245-247
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• 2017

가스터빈 시동 시 터빈휠은 급격한 온도 변화와 원심하중을 받게 된다. 터빈휠 온도와 응력은 빠르게 증가하게 되며, 적용되는 시점과 정도가 서로 다를 수 있다. 온도 및 원심력 적용 속도 차이에 따른 수명 변화를 연구하기 위해서 열-기계피로 유한요소해석을 수행하였다. 시동 시 터빈휠 속도가 천천히 증가하고, 중단 시 천천히 감속하면 상대적으로 수명이 길어진다. 만약 속도 감소가 냉각속도보다 빠르면 오히려 수명이 증가한다.

• 한국도로학회논문집
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• 제18권5호
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• pp.63-73
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• 2016

PURPOSES : The objective of this study was to analyze variations in the vehicle driving behavior characteristics on signalized intersections according to the use of traffic enforcement camera (red light camera). METHODS : In order to analyze the driving behavior characteristics on signalized intersections when red light camera are installed, the target sites for investigation were selected depending on whether the red light camera is installed and accident rates increased after the installation. In particular, to analyze the characteristics of dilemma zones in signalized intersections, approach speed and deceleration speed of 3 type vehicles (passing vehicles during a yellow light, stopping at a yellow light, passing vehicles during a green light) were examined. Based on these data, the starting point, ending point, and distance of the dilemma zones were calculated. Also, the locations of increased traffic accidents and decreased accidents after the installation of the equipment were distinguished when analyzing the traffic accident characteristics. RESULTS : Analysis results revealed that there was a tendency for the dilemma zone distance to decrease after the installation of equipment(red light camera) in most sites. This tendency was found to be due to the decrease in the approaching speed of vehicles at intersections after the installation of equipment, resulting in the starting and ending points of dilemma zone to become closer to the stop line. Moreover, analysis showed that the number of traffic accidents decreased for most intersections after the installation of equipment and safety of the intersections increased somewhat. CONCLUSIONS : In general, installation of equipment(red light camera) caused the intersections approaching speed and dilemma zone distance to decrease. Decision-making is difficult for drivers in the dilemma zone, so the decrease in the dilemma zone distance implies an improvement in traffic safety. Furthermore, the number of accidents within intersections significantly decreased after the equipment was installed, leading to the conclusion that installation of the equipment affected the decrease in traffic accidents.

• 대한기계학회논문집
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• 제17권6호
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• pp.1351-1360
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• 1993

본 연구에서는 수적법(hand lay up : HLU)을 이용하여 단 섬유포(chopped strand mat : CSM)형태의 유리섬유를 불포화 폴리에스테르 수지에 강화시킨 복합 적층 판을 대상으로 해수중에서 굽힘·피로시험을 실시하여 피로균열 성장거동을 관찰하고 파면관찰을 통하여 GERP의 피로특성을 검토하였다.