• The Journal of Korean Physical Therapy
• /
• 제28권5호
• /
• pp.308-313
• /
• 2016

Purpose: This study investigated the effects of sex hormones across menstrual cycle phases on knee muscle activity during one-leg landing in non-athletic females. Methods: Twenty-six healthy females who reported normal menstrual cycles for the previous three months were tested when estrogen levels were highest (ovulation) and lowest (menstruation). Knee muscle activity was analyzed based on electromyography (EMG) data recorded during landing on a 30-cm box. Before data collection, each subject was trained in single-leg landing tasks ten times. Landing was analyzed by measuring the average of three landing tasks. EMG data were collected between the moment of ground contact and the point of knee maximum flexion. The maximum voluntary isometric contraction (MVIC) for normalization that was recorded as the EMG root-mean-square (RMS) during landing was tested, with paired t-tests used to assess differences in knee muscle activity according to menstrual cycle phases. Results: The results showed that the soleus, semitendinosus, and lateral gastrocnemius muscle activity during landing was differed significantly during ovulation compared to that during menstruation (p<0.05). No significant differences in vastus medialis activity were found between menstrual and ovulatory phases during landing (p>0.05). Conclusion: Changes in the menstrual cycle in response to sex hormones changed the activity of muscles around the knee during landing. Females utilize different muscle activity control strategies during different phases of the menstrual cycle, which may contribute to increased ACL injury risk.

• 수산경영론집
• /
• 제18권2호
• /
• pp.53-67
• /
• 1987

In the fish industry, the perishabiliy of raw material, saeasonality of catch and diatance between production and consumption combine to cause physical distribution to be a difficult decision problem. In fishery physical distribution, the choice of appropriate landing port is a major problem. This paper deals with transshipment model to determine landing port as intermediate transfer point and the market to which fish should be sent. Transshipment model is useful to determine intermediate transfer point and can be reformulated as LP model. So this study developes transshipment model for korea large trawler ana analized the model output. It can be expended to a realistic problem in order to provide information to port planner and decision maker on the trade-offs between the cost and efficiency of fishery transportation.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2003년도 ICCAS
• /
• pp.531-536
• /
• 2003

In this paper, a redesigned guidance and control system for a lunar lander is presented. In past studies, the authors developed a trajectory and attitude control system which achieves the vertical soft landing on the lunar surface. It is confirmed that the system has a good tracking ability to a predefined profile and good robustness against a thruster failure mode where a partial failure of clustered engines was assumed. However, under the previous control laws, the landing point tends to be shifted, in response to the system parameter values, from a target point. Also, an unbalanced moment due to a thruster failure mode was not considered in the simulation. Therefore, in this study, the downrange control is added to the system to enable the vehicle to land at a pre-assigned target point accurately. Furthermore, inhibiting the effect of the unbalanced moment is attempted thorough redesigning the attitude control system. A numerical simulation was performed to confirm the ability of the proposed system with regard to the above problems. Moreover, in the past simulations, a low initial altitude was assumed as an initial condition: in this study, however, the performance of the proposed system is examined over the whole trajectory from an initial altitude of 10 [km] to the lunar surface.

• Ocean Systems Engineering
• /
• 제6권4호
• /
• pp.377-400
• /
• 2016

Dropped objects are among the top ten causes of fatalities and serious injuries in the oil and gas industry (DORIS, 2016). Objects may accidentally fall down from platforms or vessels during lifting or any other offshore operation. Proper planning of lifting operations requires the knowledge of the risk-free zone on the sea bed to protect underwater structures and equipment. To this end a three-dimensional (3D) theory of dynamic motion of dropped cylindrical object is expanded to also consider ocean currents. The expanded theory is integrated into the authors' Dropped Objects Simulator (DROBS). DROBS is utilized to simulate the trajectories of dropped cylinders falling through uniform currents originating from different directions (incoming angle at $0^{\circ}$, $90^{\circ}$, $180^{\circ}$, and $270^{\circ}$). It is found that trajectories and landing points of dropped cylinders are greatly influenced by the direction of current. The initial conditions after the cylinders have fallen into the water are treated as random variables. It is assumed that the corresponding parameters orientation angle, translational velocity, and rotational velocity follow normal distributions. The paper presents results of DROBS simulations for the case of a dropped cylinder with initial drop angle at $60^{\circ}$ through air-water columns without current. Then the Monte Carlo simulations are used for predicting the landing point distributions of dropped cylinders with varying drop angles under current. The resulting landing point distribution plots may be used to identify risk free zones for offshore lifting operations.

• 한국항공우주학회지
• /
• 제42권9호
• /
• pp.731-738
• /
• 2014

오늘날 무인기는 기술 발전을 통해 육해상의 다양한 분야에서 이용되고 있다. 한국항공우주연구원(KARI)에서는 육상용 수직이착륙기로 개발된 틸트로터 무인기를 해상에서 운용할 수 있도록 임무영역 확장을 고려하고 있다. 틸트로터 무인기의 효과적인 해상운용을 위해서는 함상이착륙이 필요하지만 해상은 지상에 비해 염분, 연무, 바람등 기상영향을 많이 받는다. 또한 지상과는 달리 선박 운동으로 인한 착륙지점의 운동이 발생하며, 자동 함상착륙을 어렵게 만든다. 이러한 무인기 함상이착륙을 위하여 본 논문에서는 파고에 따른 선박 운동을 모델링 하고, 무인기 시뮬레이터를 통해 시험평가한 결과를 제시하고 있다.

• 한국정밀공학회지
• /
• 제26권10호
• /
• pp.47-55
• /
• 2009

In this study, a robot foot having toes for firm stepping on uneven surface is proposed. The toes are connected to the lower leg by parallel links so that the lower leg can rotate in the rolling and pitching directions during stance phase without ankle joint. The landing performance of the foot on uneven surface was evaluated by relative comparison with that of the most common foot making point contact with the walking surface, since the test conditions considering real uneven surface could be hardly defined for its objective evaluation. Anti-slip margin(ASM) was defined in this study to express the slip resistance of a robot foot when it lands on a projection with half circular-, triangular- or rectangular cross section, assuming that uneven surface consists of projections having these kind of cross sections in different sizes. Based on the ASM analysis, the slip conditions for the two feet were experimentally confirmed. The results showed that the slip resistance of the new foot is not only higher than that of the conventional point contact type foot but also less sensitive to the surface friction coefficient.

• 한국운동역학회지
• /
• 제25권1호
• /
• pp.57-64
• /
• 2015

Purpose : The purpose of this study was to analyze setter toss motion kinematically according to toss types. Method : Dependent variables were elapsed time, vertical displacement of the body center, the projected speed of the ball, and differences of the joint angle to the target for four setters positioning. Result : There was no significant difference in the time but the ball contact time was shorter when the toss distance of P3 was longer. There was significant difference in the vertical displacement of COM (p<.05). The vertical displacement of COM showed that the vertical movement gradually decreased when the quick distance was longer. The vertical displacement of COM was difference (p<.05), also there was difference of the ball speed (p<.001) at the Release point(E4). There was significant difference in the knee joint angle at a certain moment among the Release(E4) and Landing point(E5)(p<.05). The hip joint was significant difference among the Apex(E2), Ball Touch(E3), Release(E4), and the Landing point(E5) on the surface(E2, E3, E4 p<.05; E5 p<.005). The shoulder angle was significant difference among the Ball Touch(E3), Release(E4) and the Landing point(E5) on the surface(E3, E4 p<.05; E5 p<.001). The elbow was significant difference in the Apex(E2) (p<.05). The wrist was significant difference in the Release(E4) (p<.05). Conclusion : If we find the clue to expect the direction of the setter's ball, we have to fine the clues in the Apex(E2) that hip join and elbow, Ball Touch(E3) that hip joint and shoulder joint, Release(E4) that wrist, elbow, hip joint, and knee joint.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2004년도 춘계학술대회
• /
• pp.438-443
• /
• 2004

Court sport shoes is consisted of several functional parts such as soles, upper and midfoot reinforcements. Currently, intensive research for court sport shoes considering functional parts is in progress world widely, but the shoes design relies only on the view point of kinesilogy and biomechanics until now. Thus, more scientific and reliable evaluation of shoes characteristics is definitely required. In this paper, we evaluate the landing impact of court sport shoes by using finite element method. We construct a shoes-leg coupled FEM model which can simulate effectively impact in running mode. From the numerical analysis results, the designer can establish the advanced design concepts and build up the detailed design standard for the specific court sport shoes under consideration.

• 대한지리학회지
• /
• 제49권1호
• /
• pp.77-90
• /
• 2014

영화에 표현된 장소 재현을 살펴보고자 인천상륙작전을 소재로 한 영화 두 편을 분석하였다. 인천상륙작전은 한국전쟁 당시 인천에 주둔했던 주체가 변화하는 전환점이자, 한국사회 이데올로기의 분기점으로 정립된 큰 사건이었던 만큼 아직까지 이에 대한 해석이 분분하다. 사례로 한국 영화 '인천상륙작전'(1965)과 북한 영화 '월미도'(1982)를 선정하였다. 제작자가 다르다는 것은 제작의도의 차이를 말한다. 제작자가 선택한 재현 대상을 밝혀 영화 속 장소를 알 수 있었다. 그 결과 상륙군 관점에서는 승리를 기념하는 스펙터클을 보여주었지만, 방어군 관점에서는 전사자들을 영웅으로 기록하고 있었다. 제작자는 실제 장소를 의도에 맞게 선택하고 표현하기에 장소 내부적 특성을 파악할 수 있으며, 그로인해 영화의 배경을 알 수 있게 한다. 이와 함께 장소 외부를 표현한 영화 속 장소는 새롭게 미장센으로 공간을 연출한다. 화면에는 보이지 않지만 대사로 전달되는 언어 재현 장소는 장소에 대해 내부자와 외부자 관계를 파악하게 한다.

• 디지털융복합연구
• /
• 제19권2호
• /
• pp.481-488
• /
• 2021

본 연구의 목적은 농구동호인의 만성발목관절불안정성(CAI)에 따른 한발착지패턴의 변화를 확인하고 비교분석하고자 하였다. 현재 부산광역시에서 레크레이션 농구경기에 참여하고 있는 농구동호인 30명을 대상으로 국제발목협회에서 제공하는 CAI 표준 선정기준에따라 CAI집단 21명과 CON집단 9명으로 분류하였다. 한발착지패턴을 측정하기 위해 초기접촉 시점 및 무릎관절 최대 굽힘 시점에서 하지정렬과 관절 움직임을 측정하고 초기접촉 시점, 발꿈치접촉 시점 및 무릎관절 최대 굽힘 시점에서 앞정강근, 긴종아리근, 안쪽장딴지근 및 중간볼기근의 활성도를 측정하였다. 그 결과, 집단 간 단일 다리 드롭랜딩 시 하지정렬과 하지 근활성도는 유의한 차이를 보이지 않았다. 이런 결과는, CAI에 따라 한발착지패턴과 근활성도에 유의한 차이가 없다는 것을 보여주었다. 추후 연구에서는 CAI를 세부적으로 구분하고 경기포지션을 고려하여 움직임의 특성 및 기능적 요구의 차이를 반영해야 할 것으로 생각된다.