• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2010년도 추계학술대회
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• pp.397-400
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• 2010

동영상은 촬영 당시의 주변의 조명변화에 의해 원치 않는 밝기 변화가 발생한다. 이러한 훼손을 플리커라 하고 시각적으로 불안정한 영상의 흔들림으로 인지된다. 플리커는 동영상 시퀸스로부터 유용한 정보를 추출하기 힘들게 하므로 미리 제거하여 안정된 형태로 만들어야 한다. 본 논문은 플리커의 발생을 감마보정요소를 포함하는 선형모델로 모델링하고 이를 분석하여 제거하는 새로운 알고리즘을 제안한다. 제안하는 알고리즘은 플리커를 유발하는 게인과 오프셋 파라미터를 분리하고 게인 요소를 감마 보정으로 추정한다. 이 과정을 통하여 추정된 게인과 오프셋 플리커 영상 시퀸스에 역으로 적용하여 플리커를 제거한다. 제안하는 방법의 객관적인 성능을 보이기 위해 움직임이 없는 인위적인 테스트 영상 시퀸스에 대해 실험한 결과와 움직임이 있는 실제 영상 시퀸스에 적용한 결과를 제시하였다.

• Clinics in Shoulder and Elbow
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• 제22권1호
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• pp.37-39
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• 2019

Irreducible dislocation of the elbow is an uncommon event. We present the case of a posterolateral elbow dislocation after a fall injury in a 67-year-old woman. A closed reduction performed in the emergency department was unsuccessful since the limited passive range of motion resulted in difficulty to perform longitudinal traction and flexion. Computed tomography images showed that the posterolateral aspect of the capitellum was impacted by the tip of the coronoid process, thus appearing similar to the Hill-Sachs lesion in the humeral head. Subsequent open reduction of the elbow revealed the dislocation to be irreducible since the tip of the coronoid process had wedged into a triangular Hill-Sachs-like lesion in the capitellum. The joint was reduced by providing distal traction on the forearm, and main fragments were disengaged using digital pressure. At the 3-month follow-up, the patient reported no dislocations, and had an acceptable range of motion. Thus, we propose that to avoid iatrogenic injury to the joint or other nearby structures, irreducible dislocations should not be subjected to repeated manipulation.

• 한국기계가공학회지
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• 제18권1호
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• pp.1-8
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• 2019

The optimal design parameters of a dynamic absorber (DA) in a machine body (that is considered as a rigid body) are discussed in this paper. The bounce and rotation motions of the rigid body have been controlled passively by a DA, which consists of a mass and a spring. The rigid body is subjected to a harmonically excited force and supported by linear springs at both ends. To define the motion of a rigid body with a DA, the equation of motion was expressed in the third-order matrix form. To define the optimal design conditions of a DA, the reduction of dynamic characteristics, represented by the amplitudes of bounce and rotation, and the transmitted powers, were evaluated and discussed. The level of reduction was found to be highly dependent on the location and spring stiffness of the DA.

• 농업과학연구
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• 제49권2호
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• pp.259-267
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• 2022

Although pesticides are recognized as necessary substances to improve agricultural production, exposure to pesticides is known to have a direct or indirect adverse effect on the reproductive function of mammals. The present study examines the effects of mancozeb, a well-known fungicide, on the fertility capacity of spermatozoa. Boar spermatozoa exposed to varying concentrations of mancozeb (0.01 - 0.5 µM) were evaluated for motility, motion kinetic parameters, viability, acrosome integrity and the generation of intracellular reactive oxygen species (ROS) after 30 min or 2 hrs of incubation. A significant reduction in the motility of spermatozoa was observed upon exposure to mancozeb. Similarly, there was a significant reduction of the motion kinematics of sperm treated with mancozeb as compared to untreated controls (p < 0.05). The sperm viability percentage and acrosome integrity also showed dose-dependent decreases upon exposure to mancozeb. High concentrations of mancozeb (0.2 - 0.5 µM) induced higher levels of intracellular ROS production, which resulted in the loss of the sperm membrane and decreased sperm motility due to oxidative stress. Taken together, the results here indicate that direct exposure to mancozeb affects the sperm fertility capacity. Hence, careful research that examines the interaction between reproduction and environmental toxins is crucial to prevent fertility disorders in animals.

• 한국정밀공학회지
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• 제13권4호
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• pp.129-135
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• 1996

The area of gear vibration and noise, has recently been the focus of many studies. The proper kinematic and geometric design of gears, the mathematical modeling of gear system are essential for a good design. This work present a gear disign for reducing noise, and practical approaches used for machinery noise reduction slong with the summary of methods available for predicting gear noise in terms of the transmis- sion error, and show a comparative study with other methods. A new tooth profile modification is proposed for reducing vibration and noise of involute gears. The method is based on the use of cubic spline curves. The tooth profile is constrained to assume an involute shape during the loaded operation. Thus the new gear profile assures conjugate motion at all points along the line of action. The new profile is found to result in a more uniform static transmission error compared to not only standard involute profile but also modificated profile therby contributing to the improvement of vibration and noise characteristics of the gear.

• 대한기계학회논문집A
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• 제28권1호
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• pp.31-39
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• 2004

This paper presents design solutions for cam type transfer unit in which feeding, lifting, and clamping motions are generated by cams. In order to achieve faster transfer motion, each designed cam must satisfy the given specifications such as velocity, acceleration, jerk, pressure angle, cam thickness, and torque. To reduce absolute torque magnitude and torque variation, a conjugate cam and a torque reduction cam are used respectively. The conjugate cam eliminates the redundant pre-load by using complementary cam to avoid jumping between a cam and a follower. The torque reduction cam reduces the torque variation by applying opposite torque to a cam shaft. The experimental result shows the reductions of the absolute torque value and torque variation. The improvement of working speed and life span of cam type transfer unit can be expected.

• 한국소음진동공학회논문집
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• 제24권5호
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• pp.407-413
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• 2014

The diesel engine and reduction gear combination is one of the common propulsion system in a naval vessel. Since the diesel engine has torsional vibration caused by reciprocating motion of the mass and gas pressure force of the cylinder, high cycle torsional fatigue can be occurred. Therefore, ROK navy restricts the maximum stress of the propulsion shaft according to MIL G 17859D. In this paper, the root cause for the failure of the diesel engine and reduction gear connecting shaft occurred in typical naval vessel is investigated based on the measured bending and torsional moment according to MIL G 17859D procedure.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 춘계학술대회논문집
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• pp.561-566
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• 2003

In this paper, a numerical method for evaluating the efficiency of vibration reduction of substructure under floating slab track is developed for optimal design of floating slab track. The equation of motion for train and track interaction system is derived by applying compatibility condition at the contact points between wheels and rails. The train is modelled by 3-masses system and the track by continuous support beam system. Numerical analyses are carried out to investigate the effects of train speed, stiffness and damping of slab-pad, and track irregularity upon vibration reduction in substructure under the track.

• 한국정밀공학회지
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• 제21권7호
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• pp.107-114
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• 2004

This paper presents a two-time scale approach for vibration reduction of a high speed Cartesian manipulator. High speed manipulators would be subject to mechanical vibration due to high inertia forces acting on linkages. To achieve high throughput capability, such motion induced vibration would have to be damped quickly, to reduce settling time of the manipulator end-effector. This paper develops a two-time scale model fer a structurally-flexible Cartesian manipulator. Based on the two-time scale model, a composite controller consisting of a computed torque method for the slow time-scale rigid body subsystem, and a linear quadratic state-feedback regulator for the fast time-scale flexible subsystem, is designed. Simulation results show that the proposed two time-scale controller yields good performance in attenuating structural vibration arising due to excitation from inertial forces.

• 수산해양기술연구
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• 제43권1호
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• pp.12-27
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• 2007

This fundamental studies on for the productivity improvement and laborsaving of purse seine fishery. Given the difficulty posed from the distortion of net shape caused by the external forces, such as tide, at the time of shooting and pursing, we set the 4 steps of 0, 2, 4 and 6cm/sec in flow velocity in the flume tank for the experiment in order to examine those characteristics. We used two model seines designed on the scale of 1 to 180 based on the power block seine, which is the mackerel purse seine generally used in the near sea of Jeju Island and triplex seine, which is the mackerel purse seine of one boat system fishing expected in the future, for the experiment, and interpreted the characteristics of several motion in water, such as the shape of seine, the change in tension and area during pursing and its the analysis results are as follows. Though the experiment could be conducted up to 6cm/sec of flow velocity that was defined, the experiment could not go on because of the severe distortion in the seine at the flow velocity in excess of 6cm/sec. As for the depth of leadline and reduction rate of side area of seine when the pursing is connected, P seine turned out to be slightly higher than T seine, and the hauling speed and reduction rate of upper area of seine were found similar to each other. The correlation between the hauling time (Ht) and depth of lead line (Dhp, Dht) of P seine and T seine can be expressed by the equation, that is, Dhp=(0.99Pt-7.63)Pt+69.01, Dht=(1.03Pt-7.73)Pt+66.74. The correlation between the hauling time and hauling velocity (Hpp, Hpt) can be expressed by the equation, that is, $Hpp=-0.06Ht^2+0.88Ht+0.78,\;Hpt=-0.05Ht^2+0.81Ht+0.98$ here, Pt is pursing time. And the correlation between the pursing time and the reduction rate of side area (sArp, sArt) can be expressed by the equation, that is, $sArp=-0.48Pt^2+14.79Pt-16.74,\;sArt=-0.45Pt^2+14.56Pt-16.48$. The reduction rate of upper area of seine (tArp, tArt) can be expressed by the equation, that is, $tArp=0.34Pt^2-0.66Pt-0.74,\;tArt=0.34Pt^2-0.27Pt-1.80$. In addition, the correlation between the pursing time and tension of purse line (Tep, Tet) can be expressed by the equation, that is, $Tep=2.79Pt^2+2.26Pt-0.60,\;Tet=2.14Pt^2+8.08Pt-27.50$.