• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.30 no.4
• /
• pp.289-296
• /
• 2017

In this paper, geometrical optimization for newly designed flapping mechanism for insect-like micro air vehicle is presented. The mechanism uses strings to convert rotation of motor to reciprocating wing motion to reduce the total weight and inertial force. The governing algorithm of movement of the mechanism is established considering the characteristic of string that only tensile force can be acted by string, to optimize the kinematics. Modified pattern search method which is complemented to avoid converging into local optimum is adopted to the geometrical optimization of the mechanism. Then, prototype of the optimized geometry is produced and experimented to check the feasibility of the mechanism and the optimization method. The results from optimization and experiment shows good agreement in flapping amplitude and other wing kinematics. Further research will be conducted on dynamic analysis of the mechanism and detailed specification of the prototype.

• 한국전산유체공학회:학술대회논문집
• /
• 2009.11a
• /
• pp.151-158
• /
• 2009

To implement the insects' flapping flight for developing flapping MAVs(micro air vehicles), the unsteady flow characteristics of the insects' forward flight is investigated. In this paper, two-dimensional FSI(Fluid-Structure Interaction) simulations are conducted to examine realistic flow features of insects' flapping flight and to examine the flexibility effects of the insect's wing. The unsteady incompressible Navier-Stokes equations with an artificial compressibility method are implemented as the fluid module while the dynamic finite element equations using a direct integration method are employed as the solid module. In order to exchange physical information to each module, the common refinement method is employed as the data transfer method. Also, a simple and efficient dynamic grid deformation technique based on Delaunay graph mapping is used to deform computational grids. Compared to the earlier researches of two-dimensional rigid wing simulations, key physical phenomena and flow patterns such as vortex pairing and vortex staying can still be observed. For example, lift is mainly generated during downstroke motion by high effective angle of attack caused by translation and lagging motion. A large amount of thrust is generated abruptly at the end of upstroke motion. However, the quantitative aspect of flow field is somewhat different. A flexible wing generates more thrust but less lift than a rigid wing. This is because the net force acting on wing surface is split into two directions due to structural flexibility. As a consequence, thrust and propulsive efficiency was enhanced considerably compared to a rigid wing. From these numerical simulations, it is seen that the wing flexibility yields a significant impact on aerodynamic characteristics.

• Korean journal of applied entomology
• /
• v.50 no.3
• /
• pp.209-214
• /
• 2011

Changes in insect communities are one of the best indicators of environmental changes. A survey was conducted using the Flight Interception Trap (FIT) method to check the changes of species composition and abundance of silphids at Mt. Sokrisan National Park from April to October in 2003 to 2007. A total of 9,704 individuals of six silphid species were examined by FIT. Among them, Nicrophorus quadripunctatus was the most dominant species with 8,763 (90.3%) individuals. There were only 971 (9.7%) individuals of the other five species. The seasonal abundance of silphids peaked in July and August. The annual abundance has decreased gradually since 2004. Therefore, the changing patterns of species composition and abundance of silphids checked by long-term monitoring could be used as environmental indicators which indirectly show the environmental changes of Mt. Sokrisan National Park.

• Journal of Wetlands Research
• /
• v.18 no.4
• /
• pp.350-356
• /
• 2016

The biggest factor in the success of breeding animals is selection of foods, which is determined by quality and quantity of habitats(Newton, 2003), in the case of This high biomass wetlands as an indicator of ecosystem function about Common Kestrel's choice of hunting area is expected to be an important clue of quality and quantity of habitats. For this study, it is divided into four types(Glasslands, Paddy fields, Dry fields, Rparian land) about Common Kestrel's hunting area in Yugu-eup, Gongju-si, Chungcheongnam-do, Recorded the behavior of Common Kestrel for three years during the breeding season from March to June(2014~2016). Result of investigation, hunting area showed a high hunting behavior in riversides and flight-hunting was frequently investigated from may to June. In addition flight-hunting's main food acquisition is mammal(the vole), while perching behavior's main food acquisition is insect according to the fact flight-hunting were mainly done in riversides, perching behavior were highly investigated than flight-hunting at glasslands and paddy fields and dry field. Hunting spot's coverage rate of plants covering the ground showed differences depending on hunting areas, but height of plants were not significant. Height of the plant according to hunting methods of flight-hunting to catch mammal(vole) was analyzed to prefer lower height than perching behavior Based on these results riversides are considered as a very important environmental factors for Common Kestrel's prey selection in breeding session.

• Journal of the Korean Society of Visualization
• /
• v.8 no.2
• /
• pp.16-22
• /
• 2010

A flow visualization has been conducted to investigate unsteady flight characteristics of a model of dragonfly. The mechanism of lift generation by flapping wings is analyzed using smoke-wire and high speed camera. The experimental results of flow visualization show a discernible sequential dynamics that three mechanisms and high incidence angle of the wings are responsible for the lift generation. The leading edge vortex by the rapid acceleration of leading edge of the wing during initial stage of stroke causes a strong lift enhancement. Delayed stall during the stroke, fast supination and pronation of the wing near the end of each stroke are also responsible for the lift generation.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.10 no.1
• /
• pp.130-143
• /
• 2007

Using steady state aerodynamic theories, it has been claimed that insects and birds cannot fly. To make matters worse, insects and birds fly at low Reynolds numbers. Therefore, a recurring theme in the literature is the importance of understanding unsteady aerodynamic effect and how the vortices behave when they separate from the moving surface that created them. In flapping flight, birds and insects can modify wing beat amplitude, stroke angle, wing planform area, angle of attack, and to a lesser extent flapping frequency to optimize the generation of lift force. Some birds are thought to employ two different gaits(a vortex ring gait and a continuous vortex gait) and unsteady aerodynamic effect(Clap and fling, Delayed stall, Wake capture and Rotational Circulation) in flapping flight. Leading edge vortices may produce an increase in lift. The trailing edge vortex could be an important component in gliding flight. Tip vortices in hovering support the body weight of the hummingbirds. Thus, this study investigated how insects and birds generate lift at low Reynolds numbers. This research is written to further that as yet incomplete understanding.

• Journal of Sericultural and Entomological Science
• /
• v.35 no.1
• /
• pp.73-76
• /
• 1993

Adding a non-fluorescent dye, Rhodamine-B, to the adult diet of uzi fly, Exorista bombysis (Louis) has shown to be a useful method for marking the eggs for flight range experiments. The method is timesaving and the dye is safe to handle and the marked eggs are easy to detect. Files fed on the diet added with dye did not have much negative effect on adult mortality and fecundity, but egg hatchability was affected.

• Korean journal of applied entomology
• /
• v.56 no.3
• /
• pp.309-314
• /
• 2017

Sampling plan using yellow sticky traps for the major strawberry flying pests - western flower thrips Frankliniella occidentalis adults, cotton aphid Aphis gossypii alate and greenhouse whitefly Trialeurodes vaporarium adults was developed to determine the initial occurrence time. The analyzed trap data were obtained from three commercial strawberry greenhouses for the whole growing season (September to May of the following year) during 2013 to 2017 in Jeju province. Three flying pests showed the aggregated distribution patterns resulted from commonly used regression techniques - Taylor's power law and Iwao's patchiness regression. Taylor's power law was better description of mean-variance relationship of the western flower thrips and the cotton aphid than Iwao's patchiness regression, otherwise greenhouse whitefly was better described by Iwao's patchiness regression. There were highly significant correlated among mean density per trap, maximum density and proportion of traps with more than 10 individuals. To estimate 4.0 heads of mean density per trap, the minimum number of traps were required 13 traps for western flower thrips, 11 traps for cotton aphid and 10 traps for greenhouse whitefly. The sequential sampling plans at the fixed precision level 0.25 were developed using parameters of Taylor's power law for western flower thrips and cotton aphid, and of Iwao's patchiness regression for greenhouse whitefly.

• Korean journal of applied entomology
• /
• v.39 no.2
• /
• pp.105-110
• /
• 2000

Sex pheromone composition was analyzed for Dichocrocis punctiferalis, which attacksapple, peach, chestnut fruits, etc., and its behavioral and field trapping studies were conducted to developa monitoring system with its sex pheromone. Virgin females showed maximum mating behavior andhairpencil extrusion behavior between 4-5 hrs after lights-off under 16L18D photoperiod and 26rf 1 "C.During this period, two sex pheromone components, ElO-hexadecenal and ZlO-hexadecenal, weredetected by GC analysis in the hexane extract of abdominal tips of virgin females. The best attraction ofmales to various synthetic sex pheromone blends was obtained at the 70 : 30 ratio of ElO-hexadecenal andZ10-hexadecenal for hair pencil extrusion and at the 80 : 20 ratio for flying upwind response. The highestattractiveness in fields was obtained between 70 : 30 and 80 : 20 from several tests in apple, peach andchestnut orchards.and chestnut orchards.

• Korean journal of applied entomology
• /
• v.61 no.1
• /
• pp.1-14
• /
• 2022

Moths have a well-developed sex pheromone communication system. Male moths exhibit an extremely sensitive and selective sex pheromone detection system so that they can detect the sex pheromone produced by conspecific females and locate them for successful mating. Using the pheromone detection system, male moths display characteristic stereotypic behavioral responses, flying upwind to follow intermittent filamentous pheromone strands in pheromone plume. The chemical composition of female sex pheromone in moths, typically comprised of multiple compounds, is species-specific. Male moths contain specialized pheromone receptor neurons on the antennae to detect conspecific sex pheromone accurately, and distinguish it from the pheromones produced by other species. The signals from pheromone receptor neurons are integrated and induce relevant behavior from the male moths. Male moths also contain olfactory sensory neurons in pheromone sensilla, specialized for pheromone-related behavioral antagonist compounds, which can enhance discrimination between conspecific and heterospecific pheromones. Here we review reports on the sex pheromone detection system in male moths and their related responses, and suggest future research direction.