• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2009년도 학술대회 초록집
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• pp.119-123
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• 2009

지하수 수위 변동에 따른 중력 변화를 이동식 기조력 중력계(PET)를 이용하여 충청남도 금산군에 위치한 국가 지하수 관측소(금산 금산 지하수관측소)에서 측정하였다. 중력 탐사는 2008년 11월부터 2009년 9월까지 약 10개월에 걸쳐 수행되었다. 또한 중력탐사가 수행되는 기간 동안 지하수 수위변화에 대한 자료도 얻었다. 얻어진 중력 자료로부터 지하수의 수위변동에 의한 효과만을 추출해 내기 위하여, 대기압에 의한 효과, 조석 효과, ocean loading 효과, polar motion과 drift 효과를 제거하였다. 이렇게 보정된 중력 자료를 관측정에서 측정한 지하수 수위변동과 직접 비교하여 중력 신호에 대한 지하수 수위 변동의 영향을 알아보았다. 또한 6월에는 지하수 관측소에 대한 양수 작업이 있었다. 이 작업이 수행되는 동안 지하수의 수위 강화와 충전이 있었으며, 이와 연관된 중력변화도 매우 성공적으로 관측되었다. 지하수 수위변동에 의한 중력 효과의 관측은 대수층의 water mass balance와 수자원에 대한 모니터링에 있어서 아주 유용하게 이용될 것으로 보인다.

• 한국운동역학회지
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• 제32권1호
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• pp.24-30
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• 2022

Objective: The purpose of this study was to determine the factors of successful and unsuccessful movements through the analysis of kinematics and muscle activity of the Free Aerial Cartwheel on the balance beam. Method: Subjects (Age: 22.8 ± 2.4 yrs., Height: 158.7 ± 5.0 cm, Body mass: 54.1 ± 6.4 kg, Career: 13 ± 2.4 yrs.) who were currently active as female gymnasts participated in the study. They had no history of surgical treatment within 3 months. Subject criteria included more than 10 years of professional experience in college and professional level of gymnastics and the ability to conduct the Free Aerial Cartwheel on the Balance Beam. Each subject performed 10 times of Free Aerial Cartwheel on the balance beam. One successful trial and one unsuccessful trial (failure) among 10 trials were selected for the comparison. Results: It was found that longer time required in case of unsuccessful trial when performing the Free Aerial Cartwheel on the balance beam compared with successful trial. It is expected to be the result of movement in the last landing section (i.e. phase 5). In addition, it was found that the center of gravity of the body descends at a high speed to perform the jump (i.e. phase 2) in order to obtain a sufficient jumping height when the movement is successful while the knee joint is rapidly extended to perform a jump when movement fails. In the single landing section after the jump (i.e. phase 4), if the ankle joint rapidly dorsiflexed after take-off and the hip joint rapidly flexed, so landing was not successful. Conversely, in a successful landing movement, muscle activity of the biceps femoris was greatly activated resulting no shaking in the last landing section (i.e. phase 5). Conclusion: In order to succeed in this movement, it is necessary to perform a strong jump after rapidly descending the center of gravity of the body using the force of the biceps femoris muscle. Further improvement of the skills on the balance beam requires the analysis of the game-like situation with continuous research on kinematic and kinematic analysis of various techniques, jumps, turns, etc.

• 전기학회논문지
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• 제64권1호
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• pp.136-142
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• 2015

In the paper, a design method of knee and pelvis joint in the biped robot is proposed for shock absorption and gravity compensation. Similarly to the human's body, the knee joints of the biped robot support most body weight and get a shock from the landing motion of the foot on the floor. The torque of joint motor is also increased sharply to keep the balance of the robot. Knee and pelvis joints with the spring are designed to compensate the gravity force and reduce the contact shock of the robot. To verify the efficiency of the proposed design method, we develope a biped robot with the joint mechanism using springs. At first, we experiment with the developed robot on the static motions such as the bent-knee posture both without load and with load on the flat ground, and the balance posture on the incline plane. The current of knee joint is measured to analyze the impact force and energy consumption of the joint motors. Also, we observe the motor current of knee and pelvis joints for the walking motion of the biped robot. The current responses of joint motors show that the proposed method has an effect on shock reduction and gravity compensation, and improve the energy efficiency of walking motions for the biped robot.

• 제어로봇시스템학회논문지
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• 제21권8호
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• pp.758-765
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• 2015

This paper proposes an attitude control system to keep the balance for a two-wheeled mobile manipulator which consists of a mobile platform and a three D.O.F. manipulator. In the conventional control scheme, complicated dynamics of the manipulator need to be derived for balancing control of a mobile manipulator. The method proposed in this paper, however, three links are considered as one body of mass and the dynamics are derived easily by using an inverted pendulum model. One of the best advantage of a sliding mode controller is low sensitivity to plant parameter variations and disturbances, which eliminates the necessity of exact modeling to control the system. Therefore the sliding mode control algorithm has been adopted in this research for the attitude control of mobile platform along the pitch axis. The center of gravity for the whole mobile manipulator is changing depending on the motion of the manipulator. And the orientation variation of center of gravity is used as reference input for the sliding mode controller of the pitch axis to maintain the center of gravity in the middle of robot to keep the balance for the robot. To confirm the performance of controller, MATLAB Simulink has been used and the resulting algorithms are applied to a real robot to demonstrate the superiority of the proposed attitude control.

• 패션비즈니스
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• 제28권1호
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• pp.83-97
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• 2024

A plantar pressure mat with visual notifications was developed to confirm whether individuals can effectively balance themselves and correct imbalances. The sensor-embedded mat was made with a commercial yoga mat, and was tested on seven working women in their 30s to determine plantar pressure distribution when standing and squatting, and if they could recognize and correct imbalances with visual feedback. The study found that visual notifications significantly changed the plantar pressure ratio of the forefoot and hindfoot, as well as the left and right foot plantar pressure ratio. Without notifications, the center of gravity was more concentrated in the rear foot than the forefoot in both standing and squatting positions. Visual notifications showed that the center of gravity, which was largely focused on the rear foot, was distributed to the forefoot, resulting in a more evenly distributed center of gravity throughout the sole. For the change in left and right plantar pressure, the weight that was largely loaded on the left side was distributed to the right foot through the visual notification mat, confirming a more balanced plantar pressure.

• 근관절건강학회지
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• 제18권1호
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• pp.16-27
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• 2011

Purpose: The purpose of this study was to investigate the effects of a visual feedbackbased balance training, using force platform biofeedback, on the postural balance of elderly faller. Methods: Fifty one community-dwelling older adults (aged 66-88 years) with a recent history of fall participated in the study. Participants were randomized to an experimental group (EG, n=25) and to a control group (CG, n=26). The EG participated in training sessions three times/week for 6 weeks. Visual feedbackbased balance training with the a computerized force platform with visual feedback screen was used in the experimental group. Static balance (center of gravity) and dynamic balance (Functional reach test, Timed "Up & Go" test, Berg balance scale) were assessed before and after end of training. Results: A significant improvement in static balance and dynamic balance were demonstrated within the EG (p<.05), but not in the CG. Conclusion: Visual feedback-based balance training may be an effective intervention to improve postural balance of elderly fallers.

• 에너지공학
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• 제9권1호
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• pp.47-53
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• 2000

This paper is to propose the concept and performance of a gravity engine which could extract energy from sea or river as a clean. renewable and sustainable power. the vertical motion of the buoyancy cylinder of the present gravity engine is converted to the mechanical work directly without any hydraulic loss. The positive net energy between the imposed and harnessed one is achieved by the specific operating procedure. The detailed derivation of the energy balance is made based on the first principle of thermodynamics. The calculation demonstrates that the present gravity engine could harness more energy than the conventional turbine system in the same basin area because of the relatively high efficiency in the energy conversion system and added mass from the buoyancy cylinder.

• 설비공학논문집
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• 제16권12호
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• pp.1167-1174
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• 2004

The method to consider gravity effect on the performance of a condenser is developed, and a simple condenser having 'nU' type two circuits is analyzed. Each circuit has the same length and inlet air-side operational conditions. The only difference between two circuits is the direction of refrigerant flow, which is exactly opposite each other between the upper 'n' type circuit and the lower 'U' type circuit. It is shown that the gravity makes the distribution of refrigerant flow uneven in the two circuits at lower refrigerant flow rates; heat transfer rate also becomes uneven. Moreover, much of the refrigerant exists as liquid state in the circuit having low refrigerant flow rate, which will make the cycle balance unstable in the refrigeration cycle system like a heat pump.

• 한국항공운항학회지
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• 제23권3호
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• pp.81-87
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• 2015

Load master is authorized to be controlled all of loading stuffs for safety of flight such as passenger, baggage, cargo and e.t.c. There are many things are missed even though the weight and balance is the most important process. This study analyzes how the differences of C.G. by among ten load masters of each careers. This study is tested how load-master takes load-control by the respective result based on differences of each practical experiences, gender and a number of certification. In result, all of load masters set C.G. on the stability region. But the practical experience of load master is relative to set better C.G. for economical effectiveness of weight and balance control work.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 합동 추계학술대회 논문집 정보 및 제어부문
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• pp.422-425
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• 2002

Position balance control refers to ability that is kept bodily center of gravity under minimum position shake on surface of land. Patients who an injury of brain, a wound of the central nervous system or weakening of leg muscular power is fallen are trend increasing steadily by the car accident body balance function is on an increasing trended. These patients have difficulty in position balance control, receive big restriction walk and life style. This research composed to do body balance function rehabilitation training which elevate leg muscular power using step machine. And expect to become effective rehabilitation training device because measuring bodily pressure center using Force Platform and do so that can confirm training result easily as that is monitor.