• Journal of Ecology and Environment
• /
• v.34 no.2
• /
• pp.167-174
• /
• 2011

Black-billed magpies (Pica pica) are a highly sedentary species due to their short and round wings, which are not adequate for long distance flights. We investigated geographic variation in the vocal signals of magpies residing in South Korea and Japan (subspecies sericea). Based on the magpie's limited dispersal ability, we predicted that the variation in vocal signals of black-billed magpies could be explained by geographic barriers such as mountain ranges and straits. We analyzed four-syllable chatter calls of magpies from five localities in South Korea, which are separated by mountain ranges (Seoul, Daejeon, Daegu, Gwangju, and Busan), and two island localities separated from the mainland by straits (Jeju in Korea and Saga in Japan). We found significant differences in the characteristics of magpie chatter calls recorded in the seven localities, and the variation pattern was independent among the variables. Mainland-island differentiation and north-south differentiation were observed. In general, magpies on Saga were the most distinctive. North-south differentiation was observed among the Korean mainland localities. However, the pattern was not related to the presence of putative geographic barriers. We hypothesize that the patterns of geographic variation in the structure of magpie chatter calls residing in South Korea might have been shaped by a sudden expansion of magpies followed by low level of local isolation, which may have led to vocal differentiation. Along with elucidating the vocal environment of Korean magpie populations, more extensive sampling is needed to clarify the functional aspects of geographic variation in the vocal signals of Korean magpies.

• Journal of The Korean Astronomical Society
• /
• v.35 no.2
• /
• pp.97-103
• /
• 2002

We have mapped 1 $deg^2$ region toward a high latitude cloud MBM 40 in the J = 1 - 0 transition of $^{12}CO$ and $^{13}CO$, using the 3 mm SIS receiver on the 14 m telescope at Taeduk Radio Astronomy Observatory. We used a high resolution autocorrelator to resolve extremely narrow CO linewidths of the molecular gas. Though the linewidth of the molecular gas is very narrow (FWHP < 1 km $s^{-1}$ ), it is found that there is an evident velocity difference between the middle upper part and the lower part of the cloud. Their spectra for both of $^{12}CO$ and $^{13}CO$ show blue wings, and the position-velocity map shows clear velocity difference of 0.4 km $s^{-1}$ between two parts. The mean velocity of the cloud is 3.1 km $s^{-1}$. It is also found that the linewidths at the blueshifted region are broader than those of the rest of the cloud. We confirmed that the visual extinction is less than 3 magnitude, and the molecular gas is translucent. We discussed three mass estimates, and took a mass of 17 solar masses from CO integrated intensity using a conversion factor $2.3 {\times} 10^{20} cm^{-2} (K\;km s^{-1})^{-1}$. Spatial coincidence and close morphological similarity is found between the CO emission and dust far-infrared (FIR) emission. The ratio between the 100 f.Lm intensity and CO integrated intensity of MBM 40 is 0.7 (MJy/sr)/(K km $s^{-1}$), which is larger than those of dark clouds, but much smaller than those of GMCs. The low ratio found for MBM 40 probably results from the absence of internal heating sources, or significant nearby external heating sources.

• Asian-Australasian Journal of Animal Sciences
• /
• v.28 no.12
• /
• pp.1686-1695
• /
• 2015

Molecular marker selection has been an acceptable tool in the acceleration of the genetic response of desired traits to improve production performance in chickens. The crossbreds from commercial parent stock (PS) broilers with four Thai synthetic breeds; Kaen Thong (KT), Khai Mook Esarn (KM), Soi Nin (SN), and Soi Pet (SP) were used to study the association among chicken growth hormones (cGH) and the insulin-like growth factor (IGF-I) genes for growth and carcass traits; for the purpose of developing a suitable terminal breeding program for Thai broilers. A total of 408 chickens of four Thai broiler lines were genotyped, using polymerase chain reaction-restriction fragment length polymorphism methods. The cGH gene was significantly associated with body weight at hatching; at 4, 6, 8, 10 weeks of age and with average daily gain (ADG); during 2 to 4, 4 to 6, 0 to 6, 0 to 8, and 0 to 10 weeks of age in $PS{\times}KM$ chickens. For $PS{\times}KT$ populations, cGH gene showed significant association with body weight at hatching, and ADG; during 8 to 10 weeks of age. The single nucleotide polymorphism variant confirmed that allele G has positive effects for body weight and ADG. Within carcass traits, cGH revealed a tentative association within the dressing percentage. For the IGF-I gene polymorphism, there were significant associations with body weight at hatching; at 2, 4, and 6 weeks of age and ADG; during 0 to 2, 4 to 6, and 0 to 6 weeks of age; in all of four Thai broiler populations. There were tentative associations of the IGF-I gene within the percentages of breast muscles and wings. Thus, cGH gene may be used as a candidate gene, to improve growth traits of Thai broilers.

• Journal of the Korean Society of Costume
• /
• v.63 no.3
• /
• pp.1-16
• /
• 2013

Xiognu people were the first of the Central-Asian nomads to establish a nation in 209 B.C. They always moved around looking for places to breed their animals and fertile grounds, so they wore clothes made of fur and leather and covered their tents with felt from the livestock. This research studies on the literatures, costumes and the achievement of archaeological excavation. Furthermore, to investigate on costumes excavated of Xiongnu, we visited the Mongolian National Museum and the Hermitage Museum. A corn-hat made of felt, a felt hat with ear flaps and a golden crown with a bird on the top were unearthed from a tomb of Xiongnu in Inner mongolia. Women usually wore pigtails, and men wore pigtails or ponytails but they cut their hair short when holding a funeral. Many pigtails discovered in Noyon uul tombs can be considered as their funeral customs. The Xiongnu wore a round or v-neck caftan attached straight sleeves reaching knees in the left folded style, and because they always rode horses, having the length of the caftan not go past their buttocks would have made it more convenient for them. During the period of Western Han, Ho refered to Xiongnu and it became a common name for northern races. They used leather belts and an animal-designed buckle was found. Women commonly rouged their cheeks for a vivid and cute look, and many ornaments were excavated including bracelets, rings and decorations made of gold, silver, copper and jade, among which there were hair ornaments used to identify one's class. A horse pattern with wings and a horn of Golmod T20 was substitution for the Schythian use of deer. Patterns or shape of unearthed articles present in the Xiongnu culture in Noyon uul had a close relationship with Altaic, Greek and Persian cultures. The Xiongnu clothing was made of animals' skin and fur, woolen textiles and felt. It was folded to the left for upper garments, and the pants were adjusted using a belt and shoes were made of leather, which was very suitable for protection against the cold and horse riding. Mobility played a significant role in their clothing.

• Proceedings of the Korean Society For Composite Materials Conference
• /
• 2005.04a
• /
• pp.51-54
• /
• 2005

Shape memory alloys (SMAs) find many applications in smart composite structural systems as the active components. Their ability to provide a high force and large displacement makes them an excellent candidate for an actuator for controlling the shape of smart structures. In this paper, using a macroscopic model that captures the thermo-mechanical behaviors and the two-way shape memory effect (TWSME) of SMAs smart morphing polymeric composite shell structures like shape-changeable UAV wings is demonstrated and analyzed numerically and experimentally when subjected to various kinds of pressure loads. The controllable shapes of the morphing shells to that thin SMA strip actuator are attached are investigated depending on various phase transformation temperatures. SMA strips start to transform from the martensitic into the austenitic state upon actuation through resistive heating, simultaneously recover the prestrain, and thus cause the shell structures to deform three dimensionally. The behaviors of composite shells attached with SMA strip actuators are analyzed using the finite element methods and 3-D constitutive equations of SMAs. Several morphing composite shell structures are fabricated and their experimental shape changes depending on temperatures are compared to the numerical results. That two results show good correlations indicates the finite element analysis and 3-D constitutive equations are accurate enough to utilize them for the design of smart composite shell structures for various applications.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.34 no.1
• /
• pp.45-52
• /
• 2010

A model of the propulsion mechanism, I, II, III was based on a two-dimensional model of the Weis-Fogh mechanism and consisted of one or two wings in a square channel. The sailing and vibration performance characteristics of model ships were tested to compare with each other. we took results as follow. Thrust of propulsion model, I and III was increased by 31% and 43%, the speed of model ship by 20% and 23%, When compared to model II in same condition. The thrust improvement using the elastic spring wing was effective not only on all models but also in the real ship. The maximum amplitude and RMS were largest at the opening angle ${\alpha}=15^{\circ}$ and smallest at ${\alpha}=30^{\circ}$ on the vibration of model ship. The thrust of propulsion model III with opening angle ${\alpha}=30^{\circ}$, phase ${\Delta}T=0^{\circ}$ was large, but the amplitude of vibration was small relatively.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.43 no.7
• /
• pp.601-608
• /
• 2015

The static aeroelastic analysis and optimization of flexible wings are conducted for steady state conditions while both aerodynamic and structural parameters can be used as optimization variables. The system of multidisciplinary design optimization as a robust methodology to couple commercial codes for a static aeroelastic optimization purpose to yield a convenient adaptation to engineering applications is developed. Aspect ratio, taper ratio, sweepback angle are chosen as optimization variables and the skin thickness of the wing. The real-coded adaptive range multi-objective genetic algorithm code, which represents the global multi-objective optimization algorithm, was used to control the optimization process. The support vector regression(SVR) is applied for optimization, in order to reduce the time of computation. For this multi-objective design optimization problem, numerical results show that several useful Pareto optimal designs exist for the flexible wing.

• International Journal of Aeronautical and Space Sciences
• /
• v.14 no.2
• /
• pp.133-139
• /
• 2013

Morphing aircraft capable of varying their wing form can operate efficiently at various flight conditions. However, radical morphing of the aircraft leads to increased structural complexities, resulting in occurrence of dynamic instabilities such as flutter, which can lead to catastrophic events. Therefore, it is of utmost importance to investigate and understand the changes in flutter characteristics of morphing wings, to ensure uncompromised safety and maximum reliability. In this paper, a study on the flutter characteristics of the folding wing type morphing concept is conducted, to examine the effect of changes in folding angles on the flutter speed and flutter frequency. The subsonic aerodynamic theory Doublet Lattice Method (DLM) and p-k method are used, to perform the flutter analysis in MSC.NASTRAN. The present baseline flutter characteristics correspond well with the results from previous study. Furthermore, enhancement of the flutter characteristics of an aluminum folding wing is proposed, by varying the outboard wing folding angle independently of the inboard wing folding angle. It is clearly found that the flutter characteristics are strongly influenced by changes in the inboard/outboard folding angles, and significant improvement in the flutter characteristics of a folding wing can be achieved, by varying its outboard wing folding angle.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.37 no.2
• /
• pp.91-98
• /
• 2017

Recently, composite materials have been mainly used in the main wings, ailerons, and fuselages of aircraft and rotor blades of helicopters. Composite materials used in rapid moving structures are subject to impact by hail, lightning, and bird strike. Such an impact can destroy fiber tissues in the composite materials as well as deform the composite materials, resulting in various problems such as weakened rigidity of the composite structure and penetration of water into tiny cracks. In this study, experiments were conducted using a 2 kW halogen lamp which is most frequently used as a light source, a 2 kW near-infrared lamp, which is used for heating to a high temperature, and a 6 kW xenon flash lamp which emits a large amount of energy for a moment. CFRP composite sandwich panels using Nomex honeycomb core were used as the specimens. Experiments were carried out under impact damages of 1, 4 and 8 J. It was found that the detection of defects was fast when the xenon flash lamp was used. The detection of damaged regions was excellent when the halogen lamp was used. Furthermore, the near-infrared lamp is an effective technology for showing the surface of a test object.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.31 no.6
• /
• pp.1-7
• /
• 2003

In this study, steady/unsteady aerodynamic characteristic for three dimensional symmetric wing was investigated numerically using Vortex Panel Method. This program utilized linearly varying vortices in x and y directions distributed on the wing surface and was applied to the incompressible potential. flow around a three dimensional wing Separation and deformation of the wake are not considered. The comparison between NACA Airfoil Data and the computed results showed excellent agreement. πus method was applied to unsteady wings undergoing both sudden pitch-up and constant rate pitching motion. In the unsteady flow analysis, a formation and a time-dependent locations of Starting Vortices are considered and the effect of Starting Vortices on aerodynamic characteristic of the wing was calculated. The present method can be extended to apply for more complicated cases such as pitching, flapping and rotating wing analysis.