Effects of temperature on asexual reproduction and somatic growth of Aurelia aurita polyps

Common moon jellyfish, Aurelia aurita s.l. has occurred abundantly in Korean coastal waters such as Gyeonggi and Masan Bay since latter half of 1990s, and damaged commercial fisheries and beach recreation. The common jellyfish A. aurita s.l. has a complex life cycle, involving an alternation of a sexual pelagic phase (medusa) and an asexual benthic phase (polyp). The polyp stage is an important component of the life cycle because the polyp is able to increase its population size through asexual reproduction (budding) and produce many ephyrae through an another asexual reproduction (strobilation). Ephyra develops into metaephyrae, and grow adult medusa. Hence, understanding of the asexual reproductions of polyp is essential to reveal the cause of recent mass occurrences of jellyfish. Present study is focused on elucidating the two different types of asexual reproductions of A. aurita polyp at colony and individual level, and extracting the relationship of somatic growth with asexual reproduction. The increase of sea water temperature has been raised as a plausible cause of recent mass occurrence of jellyfish, and indeed, it was revealed that seasonal changing seawater temperature was related with development in each life stage. Therefore, of various factor such as temperature, salinity and prey, present study revealed the effect of temperature on two asexual reproductions (budding and strobilation) and somatic growth of polyps. Particularly, polyp asexual reproduction via budding was conducted at colony and individual level, and polyp strobilation in changing water temperature. Aurelia aurita polyps rapidly increased their abundance via budding in high water temperatures (22℃ and 26℃), while their somatic growth (increase of oral disc) was insignificant. On the contrary, increase of abundance was slow in cold water (10℃ and 14℃), while their body size grew faster than that of high water temperatures. Polyps cultured in 10℃ produced pelagic larvae (ephyrae). All results suggested that polyps increase their abundance in warm seasons, and become larger in cold seasons, and the cold water temperature is favorable for strobilation. Although trends in increase of abundance and somatic growth by temperature variations between individual level and colony level were similar, the daily asexual reproduction of polyps between them were significantly different. The daily asexual reproduction rates in the individual level was constant, but decreased exponentially at colony level suggesting that the asexual reproduction rate of polyp was density dependant. Temperature variation at the 10℃ accelerated polyp strobilation, but the large variation of temperature limited number of strobilae.목차 List of tables List of Figures Abstract 제1장 서론 1.1 해파리률 1.1.1 대량발생 1.1.2 생활사 1.1.3 생식 1.1.4 식성 및 섭식특성 1.2 연구목적 제2장 재료 및 방법 2.1 재료 2.2 실험방법 2.3 분석방법 제3장 결과 및 고찰 3.1 관찰결과 3.2 실험결과 3.3 고찰 제4장 결론 참고문헌 부록1 해파리의 생활사 부록2 해파리의 각부 명칭 부록3 한국 연안에 출현하는 주요 해파

단결정 압전재료 작동기를 이용한 강체 회전형태의 지능형 조종익 구조 설계 및 해석

학위논문 (석사)-- 서울대학교 대학원 : 기계항공공학부, 2017. 2. 신상준.Researches regarding piezoelectric actuators has been conducted to substitute for the hydraulic actuators by the piezoelectric material because of light weight and accurate actuation. In this thesis, an actuating mechanism of the smart fin using single-crystal piezoelectric actuator is developed and structural analysis regarding the resulting pitch rotation angle is conducted. A straight unimorph actuator is embedded along the spanwise direction inside the hollow inner space of the airfoil. A hinge which is constrained about its axial rotation is located at 1/4 of chord, and thus the smart fin rotates in its rigid pitch direction. Structural behavior of the smart fin was predicted by using commercial software program ANSYS, regarding the resulting actuation of the trailing edge under specific voltage input in the air. In addition, the flutter analysis was conducted on the structure to confirm the stability condition under Mach number 0.5 flight.Chapter 1 Introduction 1 1.1 Background and Motivation 1 1.2 Objectives and Thesis Overview 2 Chapter 2 Theoretical Background 11 2.1 Stress Form of the Piezoelectric Matrix 11 2.2 Simple Blocked Force Beam Model: Asymmetric Actuation of Single Actuator 13 2.3 Analysis theories used in ANSYS Structural 14 2.4 Analysis Theories used in ANSYS Fluent 15 Chapter 3 Description of the Design Candidates for Smart Fin Structures 22 3.1 Design Candidate 1 22 3.2 Design Candidate 2 23 3.3 Design Candidate 3 23 Chapter 4 Numerical and Experimental Results 42 4.1 Piezoelectric actuator 42 4.2 Structural analysis of the present smart fins 50 4.2.1 Design Candidate 1 50 4.2.1 Design Candidate 2 51 4.2.3 Design Candidate 3 52 4.3 Prediction of Rotation Pitch Angle of the Smart Fin with Aerodynamic Loads 62 Chapter 5 Conclusion and Future Work 71 5.1 Conclusion 71 5.2 Future Work 73 Reference 74 국문초록 77Maste

온·오프라인 통합을 통한 닷컴 기업의 성장 전략 : 뷰티넷과 미샤 사례를 중심으로

뷰티넷(www.beautynet.co.kr)은 단순한 인터넷 쇼핑몰이 아니라 게임, 음악 등을 즐길 수 있고 블로그와 동호회 기능도 갖춘 포털 사이트의 역할을 하고 있으며 이를 토대로 성공적 오프라인 진출을 이루어 내 화장품 및 인터넷 여성 포털을 가진 최초의 코스메틱 시장의 선두의 자리에 있으며 이를 바탕으로 2005년 상반기 매출액 654억원과 성공적인 해외 시장 진출을 목표로 하고 있다. 또한, 화장품 가격 혁명을 이루며 1만 원 이하의 제품 가격으로 겉 포장과 불필요한 유통 과정을 없애므로 기존 화장품 소비자층에게 전가되는 광고 비용 등의 부담을 감소시킴으로써 온·오프라인의 장점을 충분히 발휘하고 있는 기업이다. 본 연구는 고부가 가치산업으로 통하는 화장품 산업에서 화장품 가격 3.300원이라는 전략으로 혁신적 성공을 이루어 닷컴 기업의 오프라인 취약점을 극복하고 혁신적인 성과를 보이고 있으며, 획기적 경영 전략을 통해 성공적인 오프라인 진출 모습을 보이고 있는 뷰티넷'에 대한 사례 연구이다. 온라인 비즈니스가 확보할 수 있는 자체 경쟁력을 효과적으로 발전시킨 사례로 본 연구를 통해 소규모의 사업을 계획하고 있는 사업자들에게 좋은 시사점을 제공하고자 한다

무선랜서비스(Wireless LAN Service) 사용자도입에 영향 주는 요인 연구

전자 상거래(e-commerce)에서 모바일 상거래(m-commerce)의 시대로 변화하고 있는 현 시점에서 이를 가능하게 해 주는 여러 가지 기반 서비스가 있다. 그 서비스의 중심에는 각종 애플리케이션의 이동성(mobility)에 있는데 무선랜 서비스는 이러한 이동성을 실현시키기 위한 핵심 기반 서비스인 것이다. 이러한 무선랜 서비스의 장점은 이동성, 구축의 유연성, 비용의 절감, 확장성 등을 들 수 있다. 이러한 장점으로 인하여 식당, 호텔, 응급 구조 서비스, 언론 등의 여러 분야에서 그 필요성과 중요성이 부각되고 있다. 특히 군에서는 기본적인 세부적으로 분할되어 있는 각 부서와의 상호 정보 교환 시 유선에서 발생할 수 있는 유선의 가설 및 유지 등의 문제의 해결과 아울러 각종 전투 예비량 등을 실시간으로 확인할 수 있게 되며 전장에서의 각 병사들에게 바이오센서와 퍼스널 LAN을 부착한 군복을 입게 할 경우에 중앙 부서에서 상황을 자동적으로 파악하여 군인의 생사 여부와 이동 지역 등을 실시간대로 파악하여 작전을 더 효율적으로 진행시킬 수 있는 등의 여러 장점을 보유하고 있다

분산형 통신기법을 이용한 복수 무인기의 자동 편대비행

학위논문 (박사)-- 서울대학교 대학원 : 기계항공공학부, 2016. 2. 김유단.To perform surveillance or reconnaissance of large areas effectively and efficiently, the use of multiple unmanned aerial vehicles (UAVs) flying in formation is recommended. For formation flight, a guidance and control algorithm is required. Recently, many studies have been conducted to develop algorithms for formation flight, but no centralized communication structure that is suitable for multiple UAV formation flight has become widely used. Additionally, the performance of the developed algorithms has mainly been demonstrated using numerical simulations or ground robots, which do not reflect the dynamic characteristics of UAVs. In this dissertation, a formation flight algorithm based on decentralized communication is proposed, and the performance of the proposed algorithm is verified by numerical simulations and a flight test experiment. In this study, a multiple UAV system is constructed, and a formation guidance algorithm is proposed, and its use is demonstrated in an autonomous formation flight. To develop the multiple UAV platform, a UAV hardware system, including the airframe and avionics, is constructed. An on-board decentralized information sharing method is proposed, and the effect of the communication delay is analyzed. Based on sensor information sharing, a law for guiding multiple UAVs as they perform circular and close formations is designed. Numerical simulations are performed to demonstrate the performance of the formation flight guidance and control algorithm for multiple UAVs. Finally, a flight test is performed to verify the proposed algorithm for guiding the formation flight of a multiple-UAV system.1. INTRODUCTION 1 1.1 BACKGROUNDAND OBJECTIVE 1 1.2APPROACH AND CHALLENGES 3 1.3 CONTRIBUTIONS 8 1.4 DISSERTATION OUTLINE 9 2. MULTIPLE UAV SYSTEM 11 2.1 AIRFRAME DEVELOPMENT 11 2.2 AVIONICS 14 2.3 ONBOARD DECENTRALIZED COMMUNICATION 19 2.4 UAVMODELING AND SIMULATION SETUP 27 3. FORMATION FLIGHT GUIDANCE 33 3.1 CIRCULAR FORMATION FLIGHT GUIDANCE 33 3.2 CLOSE FORMATION FLIGHT GUIDANCE 41 3.2.1 Behavioral Approach based Formation Flight Guidance 41 3.2.2 Leader-Follower Approach based Formation Flight Guidance 55 4. INTEGRATED FORMATION FLIGHT SIMULATION 75 4.1 PROCEDURE FOR AUTONOMOUS FORMATION FLIGHT 75 4.1.1 Circular Formation Flight with Separated Altitude 78 4.1.2 Circular Formation Flight at the Same Altitude 78 4.1.3 Separation and Reconfiguration Formation Flight 78 4.1.4 Close Circular Formation Flight 79 4.1.5 Close Triangular Formation Flight 79 4.2 SIMULATION RESULTS 80 5. EXPERIMENTAL RESULT 85 6. CONCLUSION 95 6.1 CONCLUDING REMARKS 95 6.2 FUTURE RESEARCH DIRECTIONS 96 BIBLIOGRAPHY 97 국문초록 103Docto

((The) empirical study on the effectiveness of mobile communication system in a hospital : focused on end-user's satisfaction

학위논문(석사) --서울대학교 대학원 :보건학과(보건정책관리학전공),2007.Maste

다공성 방풍펜스가 대기경계층내에 놓인 삼각 프리즘 표면압력에

Maste