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Use of Wing Feather Loss to Examine Age-Related Molt in Oriental Storks (Ciconia boyciana)
Yoon, Jongmin,Yoon, Hyun-Ju,Nam, Hyungkyu,Choi, Seung-Hye National Institute of Ecology 2021 국립생태원회보(PNIE) Vol.2 No.1
Reproduction and molt are costly processes in avian life histories. These two fitness-related traits are expected to be under one of physiological trade-offs. Age-related molt is known to be higher in young birds than that in adults presumably due to the cost of reproduction in adults. The present study partially replicated a previous study using a non-invasive method of seasonal wing feather loss instead of capture-inspection for molting progress in oriental storks (Ciconia boyciana). We first examined characteristics of the known six wing feather types (i.e., primaries [P], primary coverts [PC], secondaries [S], secondary coverts [SC], and tertials [T]) from two specimens with four wings. Results were utilized as references for further investigation. We then collected a total of 3,807 wing feathers shedded by 61 captive storks for one year and classified them into six wing feather types based on the reference with structures of vane (i.e., how asymmetrical) and calamus (i.e., how rigidly attached to skin) of wing feathers. Our results indicated that annual losses of all six-type wing feathers decreased with increasing ages, ranging from 29% to 58% for PC, alula, SC, P, S, and T in order. Our results were also comparable to those of a former study, suggesting that the pattern of age-specific molt might be associated with the cost of reproduction in adults. However, juveniles might shed more wing feathers with low quality formed during the previous development stage than older birds.
6자유도 모션테이블을 이용한 소형 무인항공기용 실시간 HILS 환경 구축
차형규(Hyungkyu Cha),정진석(Jinseok Jeong),시하영(Hayoung Shi),윤준석(Junseok Yoon),강범수(Beomsoo Kang) 한국항공우주학회 2019 韓國航空宇宙學會誌 Vol.47 No.5
HILS(Hardware In the Loop Simulation)를 이용한 소형 무인항공기 개발은 비용과 시간을 줄이면서 무인항공기의 신뢰성을 높이는데 효과적으로 사용될 수 있다. 또한, 실제 비행 중에 발생할 수 있는 비행제어컴퓨터의 사용 불능상태 등을 고려한 시뮬레이션을 개발과정에 반영하면, 인명 및 재산상 피해 등의 위험을 감소시킬 수 있다. 이러한 HILS를 적용하기 위해서는 실제 비행 조건과 유사한 환경을 제공할 수 있는 실시간 시뮬레이션 환경이 요구된다. 따라서 본 논문에서는 6자유도 모션테이블을 이용하여 소형 무인항공기용 실시간 HILS 환경을 구축하였다. 선행연구에서 개발된 6자유도 모션테이블을 실시간으로 HILS 환경과 연동하기 위하여, 동작 알고리즘을 위치제어 방식에서 속도제어 방식으로 변경하여 설계 하였다. 또한, 모션테이블의 실시간 동작을 확인하기 위해 역기구학 및 동작 시뮬레이션 모델을 Matlab Simulink<SUP>®</SUP>에서 모델링하고 검증하였다. Development of Small UAV using HILS (Hardware In the Loop Simulation) can be effectively used to improve the reliability of UAV (Unmanned Aerial Vehicle) while reducing cost and time. It is also possible to reduce the damage to people or property by simulating the malfunction of the Flight Control Computer (FCC) that may occur during the actual flight. For applying such HILS, a real-time simulation environment capable of providing an environment similar to an actual flight condition is required. In this paper, we constructed a real - time HILS environment for Small UAV using 6 D.O.F motion table. In order to link the 6 D.O.F motion table developed in the previous research with the HILS environment in real time, the motion algorithm was changed from the position control method to the velocity control method. Also, we implemented modeling of inverse kinematics model for command transmission in Matlab Simulink® and verified the action of motion table according to the simulation model.
외압을 받는 이중동심튜브의 신장차이에 의한 변형거동해석
김재용(JaeYong Kim),윤경호(KyungHo Yoon),김형규(HyungKyu Kim),고성호(SungHo Ko) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11
The diameter of a dual cooled fuel (DUO) including an inner flow passage to enhance thermal efficiency and safety is larger than that of a conventional fuel rod by about 1.6 times. It consists of annular pellets, coaxial inner/outer tubes and upper/lower end-plugs. Generally, the diameter and length of conventional fuel rods in a nuclear fuel assembly are differently altered due to neutron irradiation and high temperature in a reactor. Reflecting this, the coaxial inner and outer tubes will certainly grow differently. So, there occurs a technical issue, that is, whether soundness of them is maintained or not, and how those are deformed. It is necessary to investigate whether Euler’s buckling equation could be applied to DUOs or not. In this paper, we suggest a numerical methodology to predict the deformation of DUOs due to the different growth of inner and outer coaxial tubes. It was found that Euler's equation cannot be applied since the deformed shape of the fuels were different.
큰 외경 튜브집합체를 위한 삽입형 지지체의 충격강도해석
김재용(JeaYong Kim),윤경호(KyungHo Yoon),이영호(YoungHo Lee),이강희(KangHee Lee),김형규(HyungKyu Kim) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.5
Insertion type spacer grid structure for dual cooled nuclear fuel is developed to support a dual cooled fuel and to keep guide tubes straight. To evaluate the impact characteristics such as critical impact velocity, buckling strength and duration time, single impact analysis has been performed to simulate pendulum type impact test. Initial impact velocity is increased from 561 ㎜/s until the spacer grid support is buckled. 12 by 12 size spacer grid and Zircaloy-4 material are used for impact analysis. Explicit analysis is conducted by using commercial finite element analysis program, ABAQUS. The local buckling point is decided when the slope for increment of impact force is sharply descending after ascending in impact force curve via velocity. Through this analysis the dynamic failure behavior of insertion type spacer grid is predicted.