• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.435-440
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• 2007

Fish-mimetic robots or fish-mimetic propulsors have been developed or under construction. A mechanical system cannot have the same functions as bio-organic systems. Thus, the hydrodynamic characteristics of fish locomotion should be well understood in order to develop and control a feasible intelligent fish-mimetic robot with its optimal motion pattern known. In this paper, a mackerel-mimetic robot fish is fabricated in order to understand the hydrodynamic characteristics of fish locomotion. A simplified unsteady flow theory is also applied to the hydrodynamic analysis of the motion of the anterior part of the robotic fish. The normal and axial forces of the fish are measured by changing the amplitude and frequencies of fanning motion. It is found that the present theoretical results agree with the measured data.

• 한국전산유체공학회지
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• 제19권2호
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• pp.99-107
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• 2014

The aim of the present study is to investigate the flow interference between two adjacent undulating fish-like body, and its effect on the undulating propulsion. For this purpose, unsteady two dimensional incompressible flow calculations were conducted using an unstructured mesh flow solver, coupled with an overset mesh technique. To deal with mesh deformation due to fish locomotion, spring analogy is utilized. The fish body used in the simulation is constructed from the NACA0012 airfoil. The study indicates that the propulsion of undulating fish is proportional to frequency and wavelength of the midline oscillation when there is no adjacent fish. It also reveals that average thrust was increased when the vortex shedding from the tail was conserved well and pressure difference between upper and lower sides of the fish was magnified due to flow interference. From this study, which relative position and phase difference of locomotion between two fishes can generate maximum thrust was known among six different cases.

• 한국콘텐츠학회:학술대회논문집
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• 한국콘텐츠학회 2008년도 춘계 종합학술대회 논문집
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• pp.33-37
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• 2008

물고기와 수중환경의 상호작용과 물고기의 사실적인 움직임 표현은 가상 수족관을 구축할 때 매우 중요한 요소이다. 일반적으로 가상 수족관의 물고기 움직임은 3D 저작도구를 이용하여 일정한 형태의 움직임을 단순히 반복하는 유영을 보여 왔다. 본 논문에서는 물고기의 유영을 생물학적으로 분류하여 추진과 회전 특성을 분석하고, 각각의 특징에 따른 가상 물고기의 기본유영과 회전유영 생성 방법을 제안한다. 제안 방법은 사용자의 제어에 따라 다양하고 자연스러운 물고기 움직임을 생성함으로써 수중환경을 효과적으로 표현할 수 있고, 상호작용 인터페이스와 함께 사용하여 체험형 가상 수족관의 몰입감을 높일 수 있을 것이다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.870-875
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• 2008

The main objective of this paper is to control a trajectory tracking of the fish-mimetic robot by CPG (Central Pattern Generator), which is biological approach. CPG is biological neural networks that generate rhythmic movements for locomotion of animals, such as walking, running, swimming and flying. Animals show marvelous ability of autonomous dynamic adaptation for an unsteady fluid dynamic environment or various environments. So, we propose the 3-DOF CPG controller to track the trajectory of the fish robot in plane motion. The conformity of the proposed control algorithm is validated by simulation for a fish robot model, which is made by a commercial dynamic package.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 춘계학술대회논문집
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• pp.294-298
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• 2008

The ionic polymer-metal composite actuators with selectively grown multiple electrodes were developed to mimic the swimming locomotion of a fish. The developed method is based on combining electroplating with the electroless chemical reduction using the patterned mask. The advantages of this fabrication method are that the initial compositing between the polymer and platinum particles can be assured by the chemical reduction method, and the thickness of each electrode can be controlled easily and rapidly by electroplating. By using the fabricated actuator with a multiple degree of freedom, the oscillatory wave of the flexible membrane actuator was generated and a twisting motion was also realized to verify the possibility of mimicking the fish-like locomotion. The frequency response function was analyzed to investigate the natural frequency and the damping factor by a mechanical shaker and direct electrical excitation through the swept-sine method. Present results show that this novel method can be a promising technique to easily pattern each of multiple electrodes and to implement the biomimetic motion of the polymer actuators with good mechanical bending performance.

• 한국전자통신학회논문지
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• 제4권2호
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• pp.108-115
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• 2009

컴퓨터 그래픽스 기술의 발달로 인해 영화, 게임 등을 통한 컴퓨터 애니메이션을 쉽게 접할 수 있다. 사용자들은 다양한 콘텐츠를 접하게 되면서 현실세계와 흡사할 정도의 고품질 애니메이션을 요구하고 있으며, 사이버수족관 및 어류생태박물관, 어류백과사전 등을 통해서 어류의 형태나 유영방식을 관찰하고자 한다. 해저의 풍경을 표현함에 있어서 가장 핵심은 어류의 자연스럽고도 역동적인 움직임이다. 본 논문에서는 자연스러운 어류의 유영 형태를 구현하기 위해 환경 요인에 따른 어류 성장 과정 시스템을 설계하고, 어류를 표현함에 있어서 실제 어류와 흡사하게 표현하기 위해 어종별로 유영형태에 따라 다른 기준점을 적용하며, 기준점에 따른 유영속도를 산출하여 자연스러운 유영형태를 구현한다.

• 한국전자통신학회논문지
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• 제5권5호
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• pp.415-420
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• 2010

PC 성능의 향상 및 컴퓨터 그래픽스 기술의 발달로 인해 사회 각 분야에서 고품질의 컴퓨터 애니메이션이 점차 증가하고 있다. 본 연구에서는 해저의 풍경을 표현함에 있어 가장 핵심이 되는 어류 객체의 역동적이고 자연스러운 움직임을 표현하는 과정을 모핑 기법을 통하여 구현하기 위한 기준점 적용 보간법을 제안한다. 어류 객체의 꼬리 움직임에 적용시킴으로써 기존 모핑 기법이 가지고 있던 부자연스러운 속도감을 해결하고, 단조로운 움직임을 탈피한 현실감 있는 유영 방식을 구현한다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.718-721
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• 2007

The ionic-polymer-metal-composite actuators have the best merit for bio-mimetic locomotion because of their large bending performance. Especially, they have the advantage for mimicking a fish-like motion because IPMCs are useful to be actuated in water. So we have developed IPMC actuators with multiple electrodes for realization of biomimetic motion. This actuator is fabricated by combining electroless plating and electroplating techniques capable of patterning precisely and controlling a thickness of Pt electrode layer. The FRF analysis was conducted by a mechanical shaker and direct electrical excitation which is based on sweep sine wave function. From this result, the proper young‘s modulus of Platinum was investigated and applied on expecting the vibration characteristics of patterned IPMC actuator. The calculated maximum displacement of the patterned IPMC was 2.32mm under an applied 4mN/mm. The natural frequency was increased however displacement was decreased in according to increase a thickness of Pt.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 추계학술대회논문집
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• pp.119-123
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• 2006

The ionic-polymer-metal-composite actuators have the best merit for bio-mimetic locomotion because of their large bending performance. Especially, they have the advantage for mimicking a fish-like motion because IPMCs are useful to be actuated in water. So we have developed IPMC actuators with multiple electrodes for realization of biomimetic motion. Generally, the IPMC actuator has been fabricated in electroless plating technique, while it needs very long fabrication time and shows poor repeatability in the actuation performance owing to the variables in chemical fabrication process. Therefore, the novel fabrication methods were investigated by combining electroless plating and electroplating techniques capable of patterning precisely. On the whole, two different methods were compared and analyzed with similar thickness level of Platinum electrodes. Present results show that mixing chemical reduction and electroplating can be a promising candidate for electrode patterning.

• 한국자원식물학회:학술대회논문집
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• 한국자원식물학회 2019년도 추계학술대회
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• pp.85-85
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• 2019

Objective: In this study, the anti-stress effects of extract of Hydrangeae Dulcis Folium (EHDF) or ethalonic extract of Opuntiaficus-indica (EOF) of natural extracts from Jeju Island were investigated. Methods: We performed measurement of whole-body cortisol level and behavioral experiments including the novel tank test (NTT) or the open field test (OFT) to assess stress responses in zebrafish. To induce physical stress, we used the net handling stress (NHS). Fish were treated with EOF or EHDF for 6 min before they were exposed to stress. And then, we sacrificed fish for collecting body fluid from whole-body or conducted behavioural tests, including novel tank test and open field test, were evaluated to observe anxiety-like behaviours and locomotion. We used the cortisol enzyme-linked immunoassay kit to measure the amount of cortisol in each zebrafish sample. Results: The results indicate that increased anxiety-like behaviours in novel tank test and open field test under stress were prevented by treatment with both EOF and EHDF (P < 0.05). Moreover, compared with the unstressed group, which was not treated with NHS, the whole-body cortisol level was significantly increased by treatment with NHS. Compared with the NHS-treated stressed control group, pre-treatment with each EHDF and EOF for 6 min significantly prevented the NHS-increased whole-body cortisol level (P < 0.05). Conclusions: In conclusion these results suggest that both EOF and EHDF pretreatment may prevent stress responses and that its mechanism of action may be related to its positive effects on cortisol release.