• The Journal of Korea Robotics Society
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• v.7 no.4
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• pp.259-266
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• 2012

In these days, researches about underwater robots have been actively in progress for the purposes of ocean detection and resource exploration. Unlike general underwater robots such as ROV(Remotely Operated Vehicle) and AUV(Autonomous Underwater Vehicle) which have propellers, an articulated underwater robot which is called Crabster has been being developed in KORDI(Korea Ocean Research & Development Institute) with many cooperation organizations since 2010. The robot is expected to be able to walk and swim under the sea with its legs. Among many researching fields of this project, we are focusing on a swimming section. In order to find effective swimming locomotion for the robot, we approached this subject in terms of Biomimetics. As a model of optimized swimming organism in nature, diving beetles were chosen. In the paper, swimming motions of diving beetles were analyzed in viewpoint of robotics for applying them into the swimming motion of the robot. After modeling the kinematics of diving beetle through robotics engineering technique, we obtained swimming patterns of the one of living diving beetles, and then compared them with calculated optimal swimming patterns of a robot leg. As the first trial to compare the locomotion data of legs of the diving beetle with a robot leg, we have sorted two representative swimming patterns such as forwarding and turning. Experimental environment has been set up to get the motion data of diving beetles. The experimental equipment consists of a transparent aquarium and a high speed camera. Various swimming motions of diving beetles were recorded with the camera. After classifying swimming patterns of the diving beetle, we can get angular data of each joint on hind legs by image processing software, Image J. The data were applied to an optimized algorithm for swimming of a robot leg which was designed by robotics engineering technique. Through this procedure, simulated results which show trajectories of a robot leg were compared with trajectories of a leg of a diving beetle in desired directions. As a result, we confirmed considerable similarity in the result of trajectory and joint angles comparison.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.9
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• pp.782-790
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• 2013

In this paper, we propose a better solution for swimming plans of an articulated underwater robot, Crabster, with a view point of biomimetics. As a biomimetic model of underwater organisms, we chose diving beetles structurally similar to Crabster. Various swimming locomotion of the diving beetle has been observed and sorted by robotics technology through experiments with a high-speed camera and image processing software Image J. Subsequently, coordinated patterns of rhythmic movements of the diving beetle are reproduced by simple control parameters in a parameter space which make it easy to control trajectories and velocities of legs. Furthermore, a simulation was implemented with an approximated model to predict the motion of the robot under development based on the classified forward and turning locomotion. Consequently, we confirmed the applicability of parameterized leg locomotion to the articulated underwater robot through the simulated results by the approximated model.

• Journal of Sericultural and Entomological Science
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• v.50 no.1
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• pp.27-32
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• 2012

The aim of this study is to develop indoor-rearing methods of the diving beetles. In nature, both the adult diving beetle and its larvae are voracious aquatic predators. The larvae beetles hunt relatively bigger size of tadpoles and small fish for food source. However, due to difficulties of the food supplement for rearing diving beetles at indoor-condition further motivated us to develop new artificial food. Three separate experiments were performed. In the first experiment, adult beetles were provided with one of the several food choice treatments to self-compose their preferred foods that are affordable on the market at lower price. The second experiment was also to develop artificial diet that is possible for rearing larvae beetle under indoor condition. The larvae beetles were restricted to raw squid, artificial food source and mosquito larvae as a control at the first stadium and small fish and raw squid during second to third stadium duration. According to our result, adult beetles selected a food that made of boiled squid and dead small fish while, the young larvae consumed small fish, mosquito larvae and raw squid. Although, the larval food restriction on law squid caused noticeable decrease in survival, the result still supported the possible survival rate of keeping larvae at indoor condition. Moreover, pupation rate experiments, in which groups of larvae were placed at different mats, natural soil and fermented sawdust, showed that 80% of diving beetles pupated on the sawdust. This result indicates that female beetle preferentially selected to oviposit along soft and moist area.

• Korean Journal of Environmental Agriculture
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• v.30 no.2
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• pp.209-215
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• 2011

BACKGROUND: The paddy ecosystem is periodically disturbed with a relatively consistent cycle in short term. However, in long term aspect, the paddy as habitats of organisms has been affected by the change in farming practices. Accordingly, the composition and their densities of fauna species inhabiting the wet paddy has been changed. The geological distribution of a species is very helpful to understand the past and current status of habitats and biodiversity. METHODS AND RESULTS: We monitored 290 sites of open plain paddy or terraced valley paddy located in 138 cities or counties of South Korea and analyzed examine geological distribution of a taxon of freshwater invertebrates, diving beetles (Dytiscidae) which inhabited the paddy ecosystem. This survey was conducted from 2005 through 2007. The total species of diving beetles found in the paddy were identified to be 15 genus 26 species among the family of Dytiscidae. Among them, 24 species were found in the terraced valleys-in paddy fields, and 19 species were found in the open plain paddy fields. Eleven species of them were rarely found in the paddy. The average body size of the adult diving beetles of each species was between 2.0 and 35.0 mm. Most of the diving beetle species except for 11 species with rare frequency of occurrence were found in almost all sites of the terraced valley paddy fields but three species (Agabus browni, Agabus japnicus, and Ilybius apicalis) were not found in the open plain paddy fields. The species distributed relatively widely over some sites of the open plain paddy fields were Guignotus japonicus, and Rhantus pulverosus. Specifically, Ilybius apicalis was found in a specific region, the east-southern part of Korean peninsula, whereas Coelambus chinensis was found only in valley paddy field of the region where Ilybius apicalis was not found. Overall distribution range of diving beetles in open plain paddy fields was limited to few area than in terraced valley paddy fields. CONCLUSION(s): The differences in the range of distribution of diving beetles between terraced valley paddy fields and open plain paddy fields was thought to be the result of an complex action of physico-chemical environments such as annual water status and the degree of chemical application involving differences in the extent of disturbance of the paddy ecosystem, the connectivity of the paddy to an adjacent biotope, and interrelationships among competitors.

• The Journal of Korea Robotics Society
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• v.12 no.2
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• pp.228-238
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• 2017

The CALEB10 is a multi-legged biomimetic underwater robot. In the last research, we developed a swimming pattern named ESPG (Extended Swimming Pattern Generator) by observing diving beetle's swimming actions and experimented with a positive buoyancy state in which CALEB10 floats on the water. In this paper, however, we have experimented with CALEB10 in a neutral buoyancy state where it is completely immersed in water for pitch motion control experiment. And we found that CALEB10 was unstably swimming in the pitch direction in the neutral buoyancy state and analyzed that the reason was due to the weight proportion of the legs. In this paper, we propose a pitch motion control method to mimic the pitch motion of diving beetles and to solve the problem of CALEB10 unstably swimming in the pitch direction. To control the pitch motion, we use the method of controlling additional joints while swimming with the ESPG. The method of obtaining propulsive force by the motion of the leg has a problem of giving propulsive force in the reverse direction when swimming in the surge direction, but this new control method has an advantage that a propulsive moment generated by a swimming action only on a target pitch value. To demonstrate validity this new control method, we designed a dynamics-based simulator environment. And the control performance to the target pitch value was verified through simulation and underwater experiments.

• The Journal of Korea Robotics Society
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• v.9 no.1
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• pp.57-66
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• 2014

This paper describes the design concept of a bio-inspired legged underwater and estimating its performance by implementing simulations. Especially the leg structure of an underwater organism, diving beetles, is fully adopted to our designing to employ its efficiency for swimming. To make it possible for the robot to both walk and swim, the transformable kinematic model according to applications of the leg is proposed. To aid in the robot development and estimate swimming performance of the robot in advance, an underwater simulator has been constructed and an approximated model based on the developing robot was set up in the simulation. Furthermore, previous work that we have done, the swimming locomotion produced by a swimming patten generator based on the control parameters, is briefly mentioned in the paper and adopted to the simulation for extensive studies such as path planning and control techniques. Through the results, we established the strategy of leg joints which make the robot swim in the three dimensional space to reach effective controls.

• Korean journal of applied entomology
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• v.46 no.3
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• pp.335-341
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• 2007

The main habitats of diving beetles in agricultural ecosystems were identified as ponds, irrigation channels, and reservoirs, where the water system is maintained throughout the year. Four species, Cybister japonicus, Cybister brevis, Hyphydrus japonicus and Noterus angustulus, were selected as biological indicators which can be used to evaluate the healthiness of the agricultural ecosystem. The species number of 4 indicator species, the species number of diving beetle species, and the diversity index were used as factors for environmental evaluation. The evaluation was classified into grades $I{\sim}IV$. The non-fertilizer and non-pesticide agricultural practicing area and the sustainable agricultural practicing area were evaluated as grades $I{\sim}II$, and the general agricultural area to be relatively fine with a grade II. However, the analysis indicated the agricultural areas near a residential area and an industrial complex to be poor with a grade of IV, suggesting that immediate improvement in the agricultural environment is needed.

• Journal of Aerospace System Engineering
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• v.12 no.5
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• pp.16-23
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• 2018

In the paper, a robot control technique by employing Biomimetics is described. Rhythmic movements of the diving beetle's leg were analyzed and the formulated equations on the motion were drawn by applying Fourier least mean square fitting method. Simple control parameters were defined by comparing the observed locomotion through a motion capture system and reproduced motions according to changes in the values in the equation. Subsequently, the correlation of each parameter was discovered and expressed in a parameter space. Apparently, it was confirmed that various bio-mimicking motions can simply be generated for controlling the robot. Additionally, robot designing based on adopting structural advantages which the living organism possess have been briefly introduced. The proposed bio-mimicking motion generating technique was observed to be applicable to robot system developments under various environmental conditions.

• Journal of Species Research
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• v.10 no.1
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• pp.1-11
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• 2021

Evidence highlighting the importance of gut microbiota in biodiversity conservation is growing; however, gut bacteria in South Korean wildlife have not been well identified. Using a culture-dependent isolation method, we identified the gut bacteria from Korean aquatic wildlife: the gazami crab (Portunus trituberculatus), Korean striped bitterling (Acheilognathus yamatsutae), oily bitterling (Acheilognathus koreensis), leopard mandarin fish (Siniperca scherzeri), Korean dark chub (Zacco koreanus), diving beetle (Cybister lewisianus), spotted steed (Abbottina springeri), and Korean spotted sleeper (Odontobutis obscura interrupta). We identified 18 strains previously unrecorded in South Korea by comparing 16S rRNA gene sequences of isolates against the EzBioCloud and National Institute of Biological Resources(NIBR) databases. The isolated strains belong to the phyla Actinobacteria, Bacteroidetes, Firmicutes, and Proteobacteria. We also assessed for phylogenetic relatedness, Gram-stain reaction, colony and cell morphology, and biochemical characteristics. Basic information and 16S rRNA gene sequences of the isolates were registered in NIBR, and NIBR accession numbers are provided.