• 한국소음진동공학회논문집
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• 제27권1호
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• pp.14-19
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• 2017

Fuel oil consumption cost varies depending on every ship operation and this roughly amounts to 70 % of shipping companies' total revenue. As such, efforts towards improved fuel economy are being pursued. An annual 1 % reduction in fuel consumption is perceived to result in saving tens million US dollars on the global fleet operation. One approach is the application of power take-off configurations which are seen to increase fuel oil economy and are suitable for power generation. In this study, the dynamic properties of a shaft generator coupled on a 10S90ME main engine of an 18 600 TEU container vessel is presented. The vibratory torque and angular velocity variation was examined through theoretical analysis and actual vibration measurement. The result of the study suggests a review on existing classification rules for generator design and the lowering of vibratory torque and angular velocity variation guideline.

• 한국항공우주학회지
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• 제35권6호
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• pp.526-532
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• 2007

본 논문에서는 반작용 휠을 사용하는 위성체의 내고장 제어 문제를 다루고 있다. 고장은 구동기(반작용 휠)에만 발생한다고 가정하였으며, 고장에 대해서도 자세제어 성능을 유지할 수 있는 제어알고리듬을 제안한다. 자세제어 루프는 각속도 제어 루프를 포함하고 있으며, 각속도 제어 루프에 시간지연제어 기법을 적용하여 고장에 대응할 수 있도록 한다. 제안한 제어기의 안정성 조건을 제시하며, 시뮬레이션을 통해 다양한 형태의 고장에 대해 안정된 자세 추종 성능을 검증한다.

• 천문학회지
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• 제26권2호
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• pp.115-134
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• 1993

The light curve and radial velocity curve of multiperiodic dwarf cepheid VI719 Cyg (HD200925) with peculiar light curve have been reanalyzed in order to identify the oscillation modes to confirm the helium settling within the envelope. To do these, through the period search for the photometric and radial velocity data from the literature, two different periods were determined and the oscillation modes corresponding to the first and second periods were identified as the fundamental and first radial overtones. Hence the helium settling within the envelope was confirmed from the period ratio. The color excess, metallicity, effective temperature, and surface gravity corresponding to two different modes were determined and it was found that these parameters almost do not depend upon different oscillation mode. By utilizing the surface brightness method, we investigated the variation of angular diameter and radial displacement and it was found that the angular variation is very peculiar. Also by referring to the stellar models, mass and age were determined as $2.7M_{\bigodot}$ and 0.42 Gyr respectively which make this variable star heavier and younger than other multimode dwarf cepheids. Preliminary spectroscopic CCD observations were carried out and it was found that Mg in VI719 Cygni is nearly solar abundent according to the analysis of $5172.68{\AA}MgI$ line which is inconsistent with the photometric result. It was suggested that VI719 Cyg may be classified as a $\rho$ Pup stars according to the photometric characteristics.

• 비파괴검사학회지
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• 제16권4호
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• pp.241-250
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• 1997

액체/고체 경계면에서 후방 복사된 초음파의 주파수 분석에 의해 Si layer/mesh Au/Si substrate 시편에 존재하는 표면 탄성파의 주파수 의존성이 측정되었다. 사용된 광역 탐촉자(2, 5, 10MHz)의 주파수에 따라 다르게 나타난 후방 복사의 입사각 의존성은 이 현상이 표면 지역에 발생된 표면파로부터의 에너지 복사에 의한 것임을 보여주었다. 후방 산란된 초음파의 입사각 의존성을 연속적으로 측정하기 위한 초음파 각도계가 제작되었고 다른 비율의 구리 분말이 섞인 에폭시에 의해 접착된 Ni layer/Al substrate 시편에 대해 후방복사 세기의 입사각 의존성이 측정되었다. (5MHz) 후방 복사의 폭과 패턴은 표면파 속도의 주파수 의존성, layer 접합의 질 그리고 표면 지역의 구조 등 여러 정보를 가지고 있음이 밝혀졌다.

• 한국운동역학회지
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• 제20권3호
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• pp.293-301
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• 2010

The purpose of this study was to investigate the kinematic difference between skilled and less skilled group for the forward walk at dance sports rumba. Six female players(skilled group: 3, less skilled group: 3) were participated as the subjects. To obtain the three-dimensional location coordinates in the joints and segments, it shot with 100Hz/s using 8 video cameras. Step length, shoulder rotation angle, orientation angle and angular velocity of pelvis were analyzed for each trail. The skilled group showed a bigger movement than the less skilled group at the shoulder rotation angle and ROM. The skilled group showed a bigger movement than the less skilled group at the up/down obliquity and internal/external rotation movement for pelvis. And the skilled group showed a bigger movement than the less skilled group at Maximum angle (down obliquity) of P2 and Maximum angle (up obliquity) of P3 to pelvis ROM. The skilled group showed a faster angular velocity than the less skilled group at P2 (+ direction, posterior) of anterior & posterior tilt, P2 & P3 (- direction, up) of up & down obliquity, and P2 (+ direction, external) of internal & external rotation.

• 한국전문물리치료학회지
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• 제11권1호
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• pp.75-83
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• 2004

The purpose of this study was to research the effects of vocalization on upper extremity motion during occupational performance and to compare non-meaning and meaning vocalization. Experiments were performed on 30 subjects. They had no medical history of neurological problems with their upper extremities. Using a tea cup, a tea tray, and a tea spoon, they set a table during vocalization. We used meaning and non-meaning vocalization with the subjects. An example of meaning vocalization would be naming something, and an example of non-vocalization would be saying, "Ah." We used a 3-D analysis system called CMS-HS. We analyzed the motion in the angular velocity and acceleration of the elbow while recording performance time. The results of this study showed that vocalization enhanced the angular velocity and acceleration of the elbow, and also enhanced performance time. In short, vocalization improved upper extremity motion by making it faster and smoother. There were no significant differences between meaning and non-meaning vocalization.

• 로봇학회논문지
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• 제11권4호
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• pp.285-292
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• 2016

For articulated swimming robots, there have been no researches about controlling the motion or trajectory following. A control method for articulated swimming robot is suggested by extending a previous algorithm, ESPG (Extended Swimming Pattern Generator). The control method focuses on the situation that continuous pre-determined swimming pattern is applied for long range travelling. In previous studies, there has not been a way to control the propulsive force when a swimming pattern created by ESPG was in progress. Hence, no control could be made unless the swimming pattern was completed even though an error occurred while the swimming pattern was in progress. In order to solve this problem, this study analyzes swimming patterns and suggests a method to control the propulsive force even while the swimming pattern was in progress. The angular velocity of each link is influenced and this eventually modifies the propulsive force. However, The angular velocity is changed, a number of problems can occur. In order to resolve this issue, phase compensation method and synchronization method were suggested. A simple controller was designed to confirm whether the suggested methods are able to control and a simulation has affirmed it. Moreover, it was applied to CALEB 10 (a biomimetic underwater articulated robot) and the result was verified.

• Fisheries and Aquatic Sciences
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• 제9권4호
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• pp.167-174
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• 2006

Two typical responses have been documented for flatfish when they encounter the ground gear of bottom trawls: herding response and falling back response. These two responses were analyzed from video recordings of fish and were characterized by time sequences for four parameters: swimming speed, angular velocity, acceleration, and distance between the fish and the ground gear. When flatfish displayed the falling-back response, absolute values of the three swimming parameters and their deviations were significantly higher than those during the herding response. However, the swimming parameters were not dependent on the distance between the flatfish and the ground gear, regardless of which response occurred. The dominant periods for most of the movement parameters ranged from 2.0 to 3.7 s, except that no periodicity was observed for swimming speed or angular velocity during the falling-back response. However, variations in the four parameters during the falling -back response revealed greater irregularity in periodicity and higher amplitudes. This complex behavior is best described as a chaos phenomenon' and is discussed as the building block for a model predicting the responses of flatfish to ground gear as part of the general understanding of the fish capture process.

• PNF and Movement
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• 제16권1호
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• pp.151-159
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• 2018

Purpose: The aim of this study was to examine the activation of the contralateral upper and lower extremities and trunk muscle during ipsilateral upper extremity diagonal isokinetic exercise. Methods: Twenty-one healthy male subjects with no history of shoulder injury undertook ipsilateral diagonal isokinetic exercise at 60, 120, and $180^{\circ}/sec$, utilizing a standard Biodex protocol. Muscle activation amplitudes were measured in the upper trapezius, pectoralis major, biceps brachii, rectus abdominis, external oblique, rectus femoris, adductor longus, and biceps femoris muscles using electromyography. A one-way analysis of variance and paired t-tests were conducted, and the data were analyzed using SPSS, version 21.0. Results: The results revealed no statistically significant interaction between motion and angular velocity and no statistically significant contralateral muscle activation according to angular velocity (p>0.05). However, they revealed statistically significant contralateral muscle activation according to motion (p<0.05). Conclusion: These results suggest that the movements involved in contralateral upper extremity diagonal isokinetic exercise can enhance muscle strength in patients affected by stroke, fracture, burns, or arthritis.

• 한국운동역학회지
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• 제17권1호
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• pp.175-184
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• 2007

The first purpose of this study was to compare kinematic variables during spinning motion with or without upper extremity and identify the most effective spinning method. The second purpose of this study was to compare functional difference between novice and elite dancers with the term of training. Ten experienced female dancers and ten novices were recruited as subjects for this study. Elite group was asked to perform turn motion with three types of upper extremity. Novice group has taken training of spotting technique for five weeks. Four Falcon HiRES cameras were used to analyze kinematic variables including head angular velocity and CG displacement during spinning. These data were sampled before training, after 3-week, and 5-week of training. Eight different events in two consecutive turns were defined for statistical comparison. One-way ANOVA was performed to compare among the kinematics of turning motion with three types of upper extremity. Independent t-test also used to compare kinematics between elite and novice at three different length of training. As results, spinning with both arm increased angular velocity and stability compared to the turning motion with one arm or with arm strapped and found out that the turn with both arm was the most effective way of spin. Also, for novice dancers, three weeks of training were needed to complete spinning motion.