119 research outputs found
๋ฌด์ต๊ธฐํ ์ ๊ธฐ ์ถ์ง ์์ง ์ด์ฐฉ๋ฅ๊ธฐ์ ๋ํ ๋คํ์ ํด์ ๋ฐ ์๋ฎฌ๋ ์ด์ ํ๋ ์์ํฌ
ํ์๋
ผ๋ฌธ(๋ฐ์ฌ) -- ์์ธ๋ํ๊ต๋ํ์ : ๊ณต๊ณผ๋ํ ํญ๊ณต์ฐ์ฃผ๊ณตํ๊ณผ, 2023. 2. ์ด๊ด์ค.A wingless-type electric vertical take-off and landing (eVTOL) is one of the representative aircrafts utilized logistics and delivery, search and rescue, military, agriculture, and inspection of structures. For a small unmanned aerial vehicles of the wingless-type eVTOL, a quadrotor is a representative configuration to operate those missions. For a large size of the wingless-type eVTOL, it is an aircraft for urban air mobility service (UAM) specialized for intracity point-to-point due to its advantages such as efficient hover performance, high gust resistance, and relatively low noisiness.
The rotating speed of the multiple rotors in the wingless-type eVTOL has to be changed continuously to achieve stable flight. Moreover, the speed and the loaded torque of the motors also continuously change. Therefore, it is necessary to analyze the rotor thrust and torque with respect to the speed of each rotor as assigned by the controller to predict the flight performance of the wingless-type eVTOL. The electric power required by the motors is also necessary to be predicted based on the torque loaded to the motors to maintain the rotating speed.
This study suggests a flight simulation framework based on these multidisciplinary analyses including control, rotor aerodynamics, and electric propulsion system analysis. Using the flight simulation framework, it is possible to predict the flight performance of the wingless-type eVTOL for given operating conditions.
The flight simulation framework can predict the overall performance required to resist the winds and the corresponding battery energy of a quadrotor. Flight endurance of an industrial quadrotor was examined under light, moderate, and strong breeze modeled by von Kรกrmรกn wind turbulence with Beaufort wind force scale. As a result, it is found that the excess battery energy is increased with ground speed, even under the same wind conditions. As the ground speed increases, the airspeed is increased, led to higher frame drag, position error, pitch angle, and required mechanical power, consequently. Moreover, the quadrotor is not operable beyond a certain wind and ground speed since the required rotational speed of rotors exceeds the speed limit of motors.
The simulation framework can also predict the overall performance of a wingless eVTOL for UAM service. Because of its multiple rotors, rotorโrotor interference inevitably affects flight performance, mainly depending on inter-rotor distance and rotor rotation directions. In this case, there is an optimal rotation direction of the multiple rotors to be favorable in actual operation. In this study, it was proposed that a concept of rotor rotation direction that achieves the desirable flight performance in actual operation. The concept is called FRRA (Front rotors Retreating side and Rear rotors Advancing side). It was found that FRRA minimizes thrust loss due to rotor-rotor interference in high-speed forward flight. For a generic mission profile of UAM service, the rotation direction set by FRRA reduces the battery energy consumption of 7 % in comparison to the rotation direction of unfavorable rotor-rotor interference in operation.๋ฌด์ต๊ธฐํ ์ ๊ธฐ ์ถ์ง ์์ง ์ด์ฐฉ๋ฅ๊ธฐ๋ ํ๋ฐฐ ๋ฐ ์ด์ก ์๋น์ค, ์์ ๋ฐ ๊ตฌ์กฐ, ๊ตญ๋ฐฉ, ๋์
, ๊ตฌ์กฐ๋ฌผ ์ ๊ฒ๊ณผ ๊ฐ์ ๋ถ์ผ์์ ๋ํ์ ์ผ๋ก ์ด์ฉ๋๊ณ ์๋ ํญ๊ณต๊ธฐ์ด๋ค. ์ฟผ๋๋กํฐ๋ ์ด๋ฌํ ์๋ฌด๋ฅผ ์ํํ๊ธฐ ์ํ ๋ํ์ ์ธ ์ํ ๋ฌด์ต๊ธฐํ ์ ๊ธฐ ์ถ์ง ์์ง ์ด์ฐฉ๋ฅ๊ธฐ์ด๋ค. ๋ํ ๋ฌด์ต๊ธฐํ ์ ๊ธฐ ์ถ์ง ์์ง ์ด์ฐฉ๋ฅ๊ธฐ๋ ํจ์จ์ ์ธ ์ ์๋ฆฌ ๋นํ ์ฑ๋ฅ, ๋์ ๋ดํ์ฑ, ๋ฎ์ ์์ ๊ณตํด์ ๊ฐ์ ํน์ง์ผ๋ก ์ธํด ๋์ฌ ๋ด ์ดํญ ์๋น์ค๋ฅผ ์ํ ํญ๊ณต๊ธฐ๋ก ํ์ฉ๋๊ณ ์๋ค.
๋ฌด์ต๊ธฐํ ์ ๊ธฐ ์ถ์ง ์์ง ์ด์ฐฉ๋ฅ๊ธฐ์ ์ฌ๋ฌ ํ์ ๋ ๊ฐ๋ ์์ ๋ ๋นํ์ ์ ์งํ๊ธฐ ์ํด, ์ง์ํด์ ํ์ ์๋๋ฅผ ๋ณํ์ํจ๋ค. ๊ฒ๋ค๊ฐ, ๋ชจํฐ์ ํ์ ์๋์ ๋ถํ๋๋ ํ ํฌ ๋ํ ์ง์์ ์ผ๋ก ๋ณํํ๋ค. ๊ทธ๋ฌ๋ฏ๋ก ๋ฌด์ต๊ธฐํ ์ ๊ธฐ ์ถ์ง ์์ง ์ด์ฐฉ๋ฅ๊ธฐ์ ๋นํ ์ฑ๋ฅ์ ์์ธกํ๊ธฐ ์ํด, ์ ์ด๊ธฐ์์ ๊ฐ ํ์ ๋ ๊ฐ์ ๋ถ์ฌ๋ ํ์ ์๋์ ๋ฐ๋ฅธ ์ถ๋ ฅ ๋ฐ ํ ํฌ๋ฅผ ํด์ํด์ผ ํ๋ค. ๊ทธ๋ฆฌ๊ณ ์ด๋ฌํ ํ์ ๋ ๊ฐ์ ํ์ ์๋๋ฅผ ์ ์งํ๊ธฐ ์ํด ๋ชจํฐ์ ๋ถํ ๋๋ ํ ํฌ๋ฅผ ๊ธฐ๋ฐ์ผ๋ก, ๋ชจํฐ์์ ์๊ตฌ๋๋ ์ ๋ ฅ์ ์์ธกํด์ผ ํ๋ค.
๋ณธ ๋
ผ๋ฌธ์์๋ ์ ์ด, ํ์ ๋ ๊ฐ ๊ณต๋ ฅ, ์ ๊ธฐ ์ถ์ง ์์คํ
ํด์์ด ํฌํจ๋ ๋คํ์ ํด์ ๊ธฐ๋ฐ์ ๋นํ ์๋ฎฌ๋ ์ด์
ํ๋ ์์ํฌ๋ฅผ ์ ์ํ๋ค. ๋นํ ์๋ฎฌ๋ ์ด์
ํ๋ ์์ํฌ๋ฅผ ์ด์ฉํ์ฌ, ์ค์ ์ด์ฉ ํ๊ฒฝ์์์ ๋ฌด์ต๊ธฐํ ์ ๊ธฐ ์ถ์ง ์์ง ์ด์ฐฉ๋ฅ๊ธฐ ๋นํ ์ฑ๋ฅ์ ์์ธกํ ์ ์๋ค.
๋นํ ์๋ฎฌ๋ ์ด์
ํ๋ ์์ํฌ๋ฅผ ํ์ฉํ์ฌ ์ฟผ๋๋กํฐ์ ๋ํด ์ธํ์ ์ ํญํ๊ธฐ ์ํ ๋นํ ์ ๋ฐ์ ์ธ ์ฑ๋ฅ๊ณผ ๊ทธ์ ๋ฐ๋ฅธ ๋ฐฐํฐ๋ฆฌ ์๋์ง ์๋ชจ๋ฅผ ์์ธกํ์๋ค. Von Kรกrmรกn ์ธํ ๋๋ฅ์ Beaufort ์ธํ ๊ฐ๋ ๋ฑ๊ธ์ ํ์ฉํ์ฌ ๋จ์ค๋ฐ๋, ๊ฑด๋ค๋ฐ๋, ๋๋ฐ๋ ํ๊ฒฝ์ ๋ํ ์ฐ์
์ฉ ์ฟผ๋๋กํฐ์ ๋นํ์๊ฐ์ ์กฐ์ฌํ์๋ค. ๊ทธ ๊ฒฐ๊ณผ, ๋์ผํ ์ธํ ํ๊ฒฝ์ผ์ง๋ผ๋ ์ ์ง ๋นํ ์๋๊ฐ ์ฆ๊ฐํ ์๋ก ๋ฐฐํฐ๋ฆฌ ์์ ์๋์ง๊ฐ ์ฆ๊ฐํ๋ค๋ ๊ฒ์ ๋ฐํ๋ค. ์ ์ง ๋นํ ์๋์ ์ฆ๊ฐ๋ก ์ธํด ์ฟผ๋๋กํฐ์ ์ ์
๋๋ ์ ์์ด ์ฆ๊ฐํ์ฌ, ๋์ฒด ํญ๋ ฅ, ์์น ์ค์ฐจ, ๊ธฐ์ ๋ด๋ฆผ ๊ฐ๋, ์๊ตฌ ๊ธฐ๊ณ ๋๋ ฅ์ด ์ฆ๊ฐํ์๋ค. ๊ทธ๋ฆฌ๊ณ ํน์ ์ธํ ์๋์ ์ ์ง ์๋ ์ด์์์์ ์ฟผ๋๋กํฐ๋ ์๊ตฌ๋๋ ํ์ ๋ ๊ฐ์ ํ์ ์๋๊ฐ ๋ชจํฐ์ ํ์ ์๋์ ํ๊ณ๋ณด๋ค ๋์ผ๋ฏ๋ก ๋นํํ ์ ์์๋ค.
๋ํ, ๋นํ ์๋ฎฌ๋ ์ด์
ํ๋ ์์ํฌ๋ฅผ ํ์ฉํ์ฌ ๋์ฌ ์ดํญ ์๋น์ค์ฉ ๋ฌด์ต๊ธฐํ ์ ๊ธฐ ์ถ์ง ์์ง ์ด์ฐฉ๋ฅ๊ธฐ์ ์ ๋ฐ์ ์ธ ๋นํ ์ฑ๋ฅ์ ์์ธกํ์๋ค. ์ฌ๋ฌ ํ์ ๋ ๊ฐ์ ํน์ง์ผ๋ก ์ธํด, ํ์ ๋ ๊ฐ ๊ฐ ๊ฑฐ๋ฆฌ์ ํ์ ๋ ๊ฐ์ ํ์ ๋ฐฉํฅ์ ๋ฐ๋ผ ํ์ ๋ ๊ฐ ๊ฐ ๊ฐ์ญํจ๊ณผ๊ฐ ํ์ฐ์ ์ผ๋ก ๋นํ ์ฑ๋ฅ์ ์ํฅ์ ๋ฏธ์น๋ค. ์ด๋, ์ด์ฉ์ ์ ๋ฆฌํ ์ต์ ์ ํ์ ๋ ๊ฐ ํ์ ๋ฐฉํฅ์ด ์กด์ฌํ๋ค. ๋ณธ ๋
ผ๋ฌธ์์ ์ค์ ์ด์ฉ์์ ๋ฐ๋์งํ ๋นํ ์ฑ๋ฅ์ ๋ฐํํ๋ ํ์ ๋ ๊ฐ์ ํ์ ๋ฐฉํฅ์ ๋ํ ๊ฐ๋
์ธ FRRA๋ฅผ ์ ์ํ์๋ค. FRRA๋ ์ ๋ฐฉ ๋กํฐ์ ํํด ์ธก๊ณผ ํ๋ฐฉ ๋กํฐ์ ์ ์ง ์ธก์ด ์ผ์ง์ ์ผ๋ก ์ ๋ ฌ๋ ์ํ์ ํ์ ๋ฐฉํฅ์ด๋ค. FRRA ํ์ ๋ฐฉํฅ์ ๊ณ ์ ์ ์ง ๋นํ์์ ํ์ ๋ ๊ฐ ๊ฐ ๊ฐ์ญํจ๊ณผ๋ก ์ธํ ์ถ๋ ฅ ์์ค์ด ์ต์ํ๋๋ค. ํ์ ๋ ๊ฐ ๊ฐ ๊ฐ์ญํจ๊ณผ๋ก ์ธํด ๋ถ๋ฆฌํ ๋นํ ์ฑ๋ฅ์ ๊ฐ์ง๋ ํ์ ๋ฐฉํฅ ๋๋น FRRA ํ์ ๋ฐฉํฅ์ ๋์ฌ ํญ๊ณต ๊ตํต ์๋น์ค์ ๋ํ ์ผ๋ฐ์ ์ธ ์ด์ฉ์์ ๋ฐฐํฐ๋ฆฌ ์๋ชจ์จ์ด 7% ์ ๋ ๊ฐ์ํ์๋ค.Chapter 1. Introduction 1
1.1 Overview of wingless-type eVTOL 1
1.2 Previous studies about wingless-type eVTOL 6
1.2.1 Multidisciplinary analysis of control, aerodynamic, and EPS 6
1.2.2 External wind of wingless-type eVTOLs for small UAVs 9
1.2.3 Rotor-rotor interference of wingless-type eVTOLs for UAM 10
1.3 Motivation and scope of the dissertation 12
Chapter 2. Simulation Framework 16
2.1 Layout and analysis modules in simulation framework 16
2.1.1 Cascade PID control module 19
2.1.1 Aerodynamic analysis module 24
2.1.2 Electric propulsion system analysis module 30
2.1.3 6-DOF dynamics analysis module 33
2.2 Add-on modules for actual operation 37
2.2.1 Wind turbulence module 37
2.2.2 Rotor-rotor interference module 39
Chapter 3. Validation of Simulation Framework 44
3.1 Static thrust and torque on a single rotor test 44
3.2 Wind resistance test 46
3.3 Rotor-rotor interference of tandem rotors 52
3.4 Rotor-rotor interaction of a quadrotor in CFD 54
3.5 Investigation of rotor-rotor interference with respect to rotation directions in a quadrotor 58
Chapter 4. Flight Performance of Quadrotor under Wind Turbulence 65
4.1 Flight conditions 65
4.2 Wind turbulence conditions 66
4.3 Simulation results 69
Chapter 5. Flight Performance of Wingless-type eVTOL for UAM Service with Respect to the Rotor Rotation Directions 78
5.1 Hypothetical model of a wingless-type eVTOL for UAM service 78
5.2 Rotor rotation directions and aerodynamic performance 83
5.2.1 Hover flight 86
5.2.2 Forward flight at 100 km/h 88
5.2.3 Forward flight in the airspeed of 100 km/h with 30 yaw angle 93
5.3 Surrogate models including the rotor-rotor interaction effect 96
5.4 Simulation results 99
Chapter 6. Conclusion 112
6.1 Summary 112
6.2 Originalities of the dissertation 113
6.3 Future works 116
Appendix 118
References 127
๊ตญ๋ฌธ ์ด๋ก 144๋ฐ
์ด์ง์ ๋์ ๊ณต์์์์ ํ์์ ์๋์ง ํ๋ญ์ค ๋ชจ๋ธ๋ง
ํ์๋
ผ๋ฌธ (์์ฌ)-- ์์ธ๋ํ๊ต ๋ํ์ : ์ํ์กฐ๊ฒฝยท์ง์ญ์์คํ
๊ณตํ๋ถ, 2015. 2. ๋ฅ์๋ ฌ.๋์ ๊ณต์์ ๋์ ์ง์ญ ๋ด์์์ ์๋นํ ๋น์จ์ ์ฐจ์งํ์ง๋ง, ๊ธฐ์กด์ ๋์ ๊ด๋ จ ์ฐ๊ตฌ๋ค์ ๋์ ๊ณต์ ์์์ ํ์ ํก์์ ๋ํด์๋ ์ฐ๊ตฌ๊ฐ ๋ง์ด ์ด๋ค์ง์ง ์์๋ค. ์ผ๋ฐ์ ์ธ ๋์ ๊ณต์์ ๋ค์ํ ์์ข
์ ํฌ๊ดํ๊ณ , ๊ฐ๋ฐฉ์ ์๊ด๋ถ์ ๋ฐฐ์น๋ฅผ ํตํด ์๊ฐ์ , ๊ณต๊ฐ์ ์ผ๋ก ๋งค์ฐ ๋ณตํฉ์ ์ธ ๊ฒฝ๊ด์ ๊ตฌ์ฑํ๋ค. ๋ฐ๋ผ์, ๋์ ๊ณต์์์์ ๊ดํฉ์ฑ์ ๋ณด๋ค ์ ์ดํดํ๊ธฐ ์ํด์๋ ๊ดํฉ์ฑ ๋งค๊ฐ๋ณ์์ ์๊ด ๊ตฌ์กฐ ๋ณ์์ ๊ณต๊ฐ์ , ์๊ฐ์ ์ฐจ์ด๋ฅผ ๊ด์ธกํ๋ ๊ฒ์ด ํ์์ ์ด๋ค. ๋ณธ ์ฐ๊ตฌ์์๋ ์์ธ ์ฒ ๊ณต์์ ๋์์ผ๋ก, ๋ ๊ฐ์ ํต์ฌ์ ์ธ ๊ดํฉ์ฑ ๋งค๊ฐ๋ณ์ (์ต๋ ์นด๋ฅด๋ณต์ํ์จ๊ณผ ์ต๋ ์ ์ ์ ๋ฌ๋ฅ ์ ๋ํ๋ด๋ Vcmax ์ Jmax) ์ ์ฝ๋ฉด์ ์ง์์ ๊ณ์ ์ , ๊ณต๊ฐ์ ์ฐจ์ด๋ฅผ ๋ณด์ธ๋ค. ์ต๋ ์ฑ์ฅ ์๊ธฐ์ 10๊ฐ์ ์์ข
๊ฐ์ Vcmax ์ Jmax ๋ ๊ฐ๊ฐ 8๋ฐฐ, 4๋ฐฐ์ ์ฐจ์ด๋ฅผ ๋ณด์๋ค. ๊ณ์ ์ ์ผ๋ก๋ ๋ ๋ํ ์์ข
์ธ, ๋ํฐ๋๋ฌด์ ๋ฒ๋๋ฌด๊ฐ Vcmax ์์๋ ๊ฐ๊ฐ 3๋ฐฐ, 5๋ฐฐ์ ์ฐจ์ด๋ฅผ, Jmax ์์๋ 2๋ฐฐ, 5๋ฐฐ์ ์ฐจ์ด๋ฅผ ๋ณด์๋ค. ๋ณธ ์ฐ๊ตฌ๋ ๋ํ ์์ ์ง์ ํจ๋์ ํตํด ๋ ๋งค๊ฐ๋ณ์ ์ถ์ ์ด ๊ฐ๋ฅํ ์ง๋ฅผ ํ๊ฐํ๊ณ , ์ต๋ ์ฑ์ฅ๊ธฐ์ 10๊ฐ ์์ข
๋์์ ๊ด์ธก์๋ฃ์์๋ ์ง์ ํจ๋๊ณผ ๋ ๋งค๊ฐ ๋ณ์ ์ฌ์ด์์์ ์๋นํ ์๊ด๊ด๊ณ๋ฅผ ํ์ธํ์ผ๋, ๋ ์์ข
์ ์ฌ๋ฌ ๊ณ์ ๊ฐ ๊ด์ธก์๋ฃ๋ฅผ ๋ถ์ํ ๊ฒฐ๊ณผ์์๋ ์๊ด๊ด๊ณ๋ฅผ ํน์ ์ง์ ์ ์์๋ค. ์ฝ๋ฉด์ ์ง์๋ ํ์ฅ ๊ด์ธก๊ณผ ์์ฑ ์๊ฒฉ ํ์ฌ ์์์ ํตํด ๊ณ์ฐํ์ผ๋ฉฐ, ์๊ฐ์ , ๊ณต๊ฐ์ ์ผ๋ก ๋น์ ๊ท๋ถํฌ๋ฅผ ๋ณด์ด๋ฉฐ ํฐ ์ฐจ์ด๋ฅผ ๋ํ๋๋ค. ์ ๊ตํ๊ฒ ๋์ ๊ณต์ ๋ด ๋ณตํฉ์ ์ธ ๊ตฌ์กฐ์ ํน์ฑ์ ๋ฐ์ํ 3์ฐจ์ ๋ชจ๋ธ์ ํ์์ ์๋์ง ํ๋ญ์ค๋ฅผ ๋น๊ต์ ์ ํํ ์ถ์ ํ๋ค. ๋ํ, ๊ฐ์ ์๋๋ฆฌ์ค๋ฅผ ํ์ฉํ ๋ชจ๋ธ ์๋ฎฌ๋ ์ด์
์ ์๋ชฉ์ ๋ถํฌ์ ๊ฐ๋ณ ์๊ด์ ํฌ๊ธฐ์ ๋ฐ๋ฅธ ํจ๊ณผ๋ฅผ ๋ช
ํํ ๋ณด์ฌ์ฃผ์๋ค. ์๋ชฉ ๋ถํฌ ์ฐจ์ด๋ ํ์ ๋ฐ ์๋์ง ํ๋ญ์ค ๊ฒฐ๊ณผ์์ ์ต๋ 3 % ์ ์ฐจ์ด๋ง์ ๋ณด์๊ณ , ๋ฐ๋ฉด์ ๊ฐ๋ณ ์๊ด์ ํฌ๊ธฐ ์ฐจ์ด๋ ์ต๋ 40% ์ ํฐ ์ฐจ์ด๋ฅผ ๋ณด์๋ค. ๋ณธ ๊ฒฐ๊ณผ๋ ๊ฐ๊ฐ์ ์์๊ฐ ํ์์์ง ๋ฐ ์๋์ง ๋ถํ ์ ๋ฏธ์น ์ ์๋ ํจ๊ณผ๋ฅผ ํ๊ฐํ ์ ์๋ ๋๊ตฌ์์ ์์ฌํ๋ค. ์์์ ์ ์๋ ๋ณธ ๋
ผ๋ฌธ์ ๊ฒฐ๊ณผ๋ค์ ์ ํํ ๊ดํฉ์ฑ ์ถ์ ์ ์ํด ๊ดํฉ์ฑ ๋งค๊ฐ๋ณ์ ๋ฐ ์ฝ๋ฉด์ ์ง์์ ๊ณต๊ฐ์ , ์๊ฐ์ ๋ณ์ด๋ฅผ ๊ณ ๋ คํจ์ด ์ค์ํจ์ ๋ถ๊ฐ์ํฌ ๋ฟ ์๋๋ผ, ๊ณต์ ์ค๊ณ์ ํ๊ฐ ํ๋ซํผ์ผ๋ก์์ 3์ฐจ์ ๋ชจ๋ธ๋ง์ ์ ์ฌ์ ์ญํ ์ ์์ฌํ๋ค.Parks account for a large proportion of green spaces in urban regions, but most previous studies have focused on the values of recreational services in urban parksโcarbon uptake by plants in urban parks has been studied less extensively. Urban parks typically form complex landscapes in space and time by integrating multiple species with open canopies. Thus, to better understand canopy photosynthesis in urban park, measuring spatial and temporal variations in photosynthetic parameters and canopy structural variables is essential. Here, we report seasonal and spatial variations in two key photosynthetic parameters (Vcmax and Jmax which are the maximum rates of carboxylation and electron transport, respectively) and leaf area index (LAI) in Seoul Forest Park. During the peak growing season, we found an eightfold difference (20 to 149 ฮผmol m-2 s-1) and fourfold difference (38 to 141 ฮผmol mโ2 sโ1) in Vcmax and Jmax, respectively, across 10 species. Over the seasons, two woody species (Zelkova serrata and Prunus yedoensis Matsum) respectively showed three- to fivefold differences in Vcmax and two- to fivefold differences in Jmax. We evaluated whether leaf nitrogen contents could predict Vcmax and Jmax, and found significant correlations among the three variables during the peak growing season across 10 species, but no significant correlations among them over the seasons in the two woody species. LAI computed using in- situ observations and satellite remote-sensing imagery showed a non-normal distribution with marked variation during the growing season. A sophisticated 3 dimensional model, which reflects complexity of vegetation structure in the park, well predicted carbon and energy fluxes for a day. Moreover, the model simulation with simplistic virtual scenarios clearly showed the effects of difference in tree distribution and tree size on carbon and energy fluxes (~ 3 % and ~ 40 %, respectively). These results highlight not only necessity of consideration of spatial and temporal variability in photosynthetic parameters and LAI for accurate estimation of canopy photosynthesis in urban parks, but also an important role of individual tree based model as a potential park design evaluating platform.CONTENTS
ABSTRACT
CONTENTS
LIST OF TABLES
LIST OF FIGURES
I. INTRODUCTION
II. MATERIALS AND METHODS
1. Site
2. Photosynthetic parameters and leaf traits measurement
3. Leaf area index measurement
3.1. Plot design
3.2. Digital cover photography
4. Satellite remote-sensing data processing
5. Model simulation
5.1. Model description
5.2. Collecting crown data
5.3. Flux measurement
5.4. Simulations with virtual scenarios
III. RESULT AND DISCUSSION
1. To what extent do photosynthetic parameters vary spatially during the peak growing season and temporally across the seasons?
2. Can Vcmax and Jmax be estimated indirectly from leaf traits data?
3. To what extent does the LAI vary across different land cover types over the seasons?
4. Can park design strategy affect carbon and energy fluxes?
5. Broader implications for future urban park design
IV. SUMMARY AND CONCLUSIONS
REFERENCE
ABSTRACT (Korean)
ACKNOWLEDGEMENTMaste
An Iterative Detection Algorithm of Bootstrap Signals for ATSC 3.0 System
๋ณธ ํ์๋
ผ๋ฌธ์์๋ ATSC 3.0 ์์คํ
์ ์ํ ๋ถํธ์คํธ๋ฉ ์ ํธ์ ๋ฐ๋ณต ๊ฒ์ถ ์๊ณ ๋ฆฌ์ฆ์ ์ ์ํ๋ค. ๋ถํธ์คํธ๋ฉ ์ ํธ์ ํฌํจ๋ ์๊ทธ๋๋ง ์ ๋ณด๋ฅผ ๊ฒ์ถํ๊ธฐ ์ํ ์ต๋์ฐ๋ ๊ฒฐ์ ๊ท์น์ ์ ๋ํ์๊ณ , ๊ฒ์ถ ์ฑ๋ฅ์ ํฅ์์ํค๊ธฐ ์ํ ๋ฐ๋ณต ๊ฒ์ถ ์๊ณ ๋ฆฌ์ฆ์ ์ ์ํ๋ค. ์ ์ํ๋ ๊ฒ์ถ ์๊ณ ๋ฆฌ์ฆ์ ์ฐ์ํ๋ ์ด์ ๋ ๊ฐ์ ๋ถํธ์คํธ๋ฉ ์ฌ๋ณผ์ ๋ํ ์ฑ๋ ์ถ์ ๊ฐ๋ค์ ๋ฐ๋ณต์ ์ผ๋ก ํ๊ท ํ๋ค. ๋ํ, ๋ณธ ํ์๋
ผ๋ฌธ์์๋ ์ ์ํ๋ ๊ฒ์ถ ์๊ณ ๋ฆฌ์ฆ์ ์์ ๊ธฐ ๋ณต์ก๋๋ฅผ ๋ถ์ํ์๋ค. ์ ์ฐ ์คํ ๊ฒฐ๊ณผ๋ ๊ธฐ์กด ๋ฐฉ๋ฒ๊ณผ ๋น๊ตํ์ ๋ ํ๋ ์ ์ค์จ์ด ์ธ ๊ฒฝ์ฐ ์ฝ 2 dB์ ์ ํธ ๋ ์ก์๋น ์ด๋์ ์ป์ ์ ์์์ ๋ณด์ฌ์ค๋ค. ๋ํ, ๊ฒ์ถ ์ฑ๋ฅ๊ณผ ๋ณต์ก๋๋ฅผ ๊ณ ๋ คํ ์ต์ ์ ๋ฐ๋ณต ํ์๋ฅผ ์ ์ํ์๋ค.|In this thesis, an iterative detection algorithm of bootstrap signals for ATSC 3.0 system is proposed. A maximum-likelihood decision rule to detect the signaling information included in the bootstrap signals is derived and the iterative detection algorithm to improve the detection performance is described. The proposed detection algorithm iteratively averages the channel estimates for the two consecutive symbols. Furthermore, this thesis analyzes the computational complexity of the proposed detection algorithm. The simulation results show that the proposed detection algorithm can obtain the signal-to-noise ratio gain of approximately 2.0 dB at frame error rate of compared to the conventional detection scheme. Also, this thesis presents the sufficient number of iterations to provide a good performance-complexity trade-off.1. ์ ๋ก 1
2. ATSC 3.0 ๋ฐ ๋ถํธ์คํธ๋ฉ ์ ํธ์ ๊ตฌ์กฐ 3
2.1 ATSC 3.0 ๊ฐ์ 3
2.2 ๋ถํธ์คํธ๋ฉ ์ ํธ์ ๊ตฌ์กฐ 5
2.2.1 ๋ถํธ์คํธ๋ฉ ์ ํธ ์์ฑ 5
2.2.2 ๋ถํธ์คํธ๋ฉ ์ ํธ์ ์ํ ์ด๋ 11
2.2.3 ๋ถํธ์คํธ๋ฉ ์ ํธ์ ์๊ฐ ์์ญ ๊ตฌ์กฐ 14
2.2.4 ๋ถํธ์คํธ๋ฉ ์ ํธ์ ์๊ทธ๋๋ง ๊ตฌ์กฐ 15
3. ๋ถํธ์คํธ๋ฉ ๊ฒ์ถ๊ธฐ 19
3.1 ๋ถํธ์คํธ๋ฉ ์์ ๊ธฐ 19
3.2 ๋ถํธ์คํธ๋ฉ ์ ํธ ๊ฒ์ถ์ ์ํ ์ต๋์ฐ๋ ๊ฒฐ์ ๊ท์น 20
4. ๋ถํธ์คํธ๋ฉ ๊ฒ์ถ์ ์ํ ์ ์ํ๋ ๋ฐ๋ณต ๊ฒ์ถ ์๊ณ ๋ฆฌ์ฆ 24
4.1 ์ฑ๋ ์ถ์ 24
4.2 ์๋ฐฉํฅ ๊ฒ์ถ 24
4.3 ์ญ๋ฐฉํฅ ๊ฒ์ถ์ ์ํ ์ต๋์ฐ๋ ๊ฒฐ์ ๊ท์น 27
4.4 ๋ฐ๋ณต ๊ฒ์ถ 29
5. ๋ณต์ก๋ ๋ถ์ 33
6. ์ ์ฐ ์คํ ๊ฒฐ๊ณผ 35
7. ๊ฒฐ๋ก 52
์ฐธ๊ณ ๋ฌธํ 53
๊ฐ์ฌ์ ๊ธ 57Maste
๊ทผ์นจ์ค์ฑ ๋ฐฉ๊ด์์ ๋ํ ์์ ํ ๋ณด์กฐ ํญ์์น๋ฃ: ์ฒด๊ณ์ ๋ฌธํ๊ณ ์ฐฐ ๋ฐ ๋ฌด์์๋ฐฐ์ ์์์ํ๋ค์ ๋ํ ๋คํธ์ํฌ ๋ฉํ๋ถ์
ํ์๋
ผ๋ฌธ (๋ฐ์ฌ)-- ์์ธ๋ํ๊ต ๋ํ์ : ์๊ณผ๋ํ ์ํ๊ณผ, 2018. 2. ๊ตฌ์ํ.95% CI, 0.68-0.92) than RC alone. In the network meta-analysis, the gemcitabine/cisplatin/paclitaxel (GCP) combination was the only ACH regimen associated with significant improvement in both the PFS (HR, 0.3895% CrI, 0.25-0.58) and OS (HR, 0.3895% CrI, 0.22-0.65).
Conclusions: ACH following RC for MIBC may therefore contribute to improved PFS and OS. In particular, the GCP combination may be the optimal ACH regimen for improving postoperative survival outcomes. Additional well-designed, large scale, prospective, randomized trials are still required to establish the optimal ACH regimen in MIBC patients.Objective: Although adjuvant chemotherapy (ACH) is widely used in clinical practice for the management of muscle-invasive bladder cancer (MIBC), a consensus has yet to be established on which ACH regimen is the most effective for improving postoperative survival. In this study, we aimed to systematically assess the optimal ACH regimen for improving survival outcomes in patients treated with radical cystectomy (RC) for MIBC.
Materials and Methods: A comprehensive literature search was conducted in the PubMed, Embase, and the Cochrane Library databases for all articles published until December 2016 in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. The study end-points were progression-free survival (PFS) and overall survival (OS). A direct pairwise meta-analysis was conducted by pooling the studies that compared RC with ACH and RC alone, and the results are presented as a pooled hazard ratio (HR) with a 95% confidence interval (CI). A Bayesian network meta-analysis was adopted for indirect comparisons among various ACH regimens, and the outcomes are presented as HRs with 95% credible intervals (CrI).
Results: The eleven randomized controlled trials ultimately selected for the current analysis comprised of 1,546 patients with 49 to 327 subjects per study. Based on the pairwise meta-analysis, the use of ACH showed significantly better PFS (HR, 0.6495% CI, 0.49-0.85) and OS (HR, 0.79Introduction 1
Materials and Methods 3
Results 10
Discussion 29
Conclusions 35
References 36
Abstract in Korean 43Docto
An efficient prefetching algorithm for fast address translation in a PCM controller
ํ์๋
ผ๋ฌธ(์์ฌ) -- ์์ธ๋ํ๊ต๋ํ์ : ๊ณต๊ณผ๋ํ ์ ๊ธฐยท์ ๋ณด๊ณตํ๋ถ, 2021.8. ์ดํ์ฌ.DRAM์ ์ค์ผ์ผ๋ง ๊ธฐ์ ์ ํ๊ณ์ ๋๋ฌํ๊ณ ์ด์ ๋ฐ๋ผ DRAM์ ๋์ฒดํ ์ฌ๋ฌ ์ฐจ์ธ๋ ๋ฉ๋ชจ๋ฆฌ ๊ธฐ์ ์ด ์ ์๋์๋ค. ๊ทธ ์ค ์ ๋ณํ ๋ฉ๋ชจ๋ฆฌ (phase change memory, PCM)๋ ๋ฌผ์ง์ ์ ๋ณํ๋ฅผ ํตํ ์ ํญ ๋ณํ๋ก ๋ฐ์ดํฐ๋ฅผ ์ ์ฅํ๋ฉฐ ์ด์ ๋ฐ๋ผ ํจ๊ณผ์ ์ธ ์ค์ผ์ผ๋ง์ด ๊ฐ๋ฅํ๋ค. PCM์ ์ ๊ทผํ๊ธฐ ์ํด PCM controller์์ ๋
ผ๋ฆฌ์ ์ฃผ์๋ฅผ ๋ฌผ๋ฆฌ์ ์ฃผ์๋ก ๋ณํํ๋ ๊ณผ์ ์ ๊ฑฐ์น๋ค. ์ฃผ์ ๋ณํ ์์ฒญ ๋ฐ์ ์ DRAM์ ์ ๊ทผํ์ฌ ์ฃผ์ ๋ณํ ๋ฐ์ดํฐ๋ฅผ ๋ฐ์์จ๋ค. ์ฃผ์ ๋ณํ์ ์ํ ์ง์์ ์ธ ๋ฉ๋ชจ๋ฆฌ ์ ๊ทผ์ ์ ์ฒด์ ์ธ ์ฑ๋ฅ ์ ํ๋ฅผ ์ผ๊ธฐํ๋ค. Prefetcher๋ ์ด๋ฌํ ๋ฌธ์ ๋ฅผ ํจ๊ณผ์ ์ผ๋ก ํด๊ฒฐํ ์ ์๋ค. PCM workload์ ๊ฒฝ์ฐ ์ ๋ฐฉํฅ ์์ฐจ ํจํด ๋ฐ ์ญ ๋ฐฉํฅ ์์ฐจ ํจํด์ด ์ฃผ๋ฅผ ์ด๋ฃฌ๋ค. ๋ํ ์ผ๋ถ ๋น ์์ฐจ ํจํด์ ๊ฒฝ์ฐ PCM workload ๋ด์ ์กด์ฌํ๋ ์์ฐจ ํจํด๊ณผ ์ฐ๊ด์ฑ์ ๊ฐ์ง๊ณ ์๋ค. ์ด๋ฌํ ๋น ์์ฐจ ํจํด์ ๊ฒฝ์ฐ ๋๋ ทํ ํจํด์ด ์กด์ฌํ์ง ์์ ๊ธฐ์กด์ prefetch ์๊ณ ๋ฆฌ์ฆ์ผ๋ก ์ฑ๊ณต์ ์ธ prefetch๋ฅผ ์งํํ ์ ์๋ค. ๋ณธ ์ฐ๊ตฌ์์ ์ ์ํ๋ prefetcher๋ stream prefetcher์ ์ ์ฌํ ๋ฐฉ์์ ํํจ์ผ๋ก ์์ฐจ ํจํด์ ํจ์จ์ ์ผ๋ก ํ์งํ ์ ์๋ค. ๋ฟ๋ง ์๋๋ผ endurance์ depth parameter๋ฅผ ํตํด ๋๋ ทํ ํจํด์ด ์กด์ฌํ์ง ์์ง๋ง workload ๋ด ์์ฐจ ํจํด๊ณผ ์ฐ๊ด์ฑ์ ๊ฐ์ง๋ ํจํด์ ๋ํด prefetch hit์ ๋ฐ์์ํฌ ์ ์๋ค. ์ ์ํ prefetcher์ ๊ฒฝ์ฐ ๊ธฐ์กด prefetch ์๊ณ ๋ฆฌ์ฆ ๋๋น 7% ์ด์์ ์ ์ฒด ์์คํ
์ฑ๋ฅ ํฅ์์ ๋ณด์๋ค. ๋ํ prefetch๋ฅผ ์งํํ์ง ์์์ ๊ฒฝ์ฐ์ ๋นํด ์ฃผ์ ๋ณํ ์๊ฐ์ 17% ์์ค์ผ๋ก ๋จ์ถ์์ผฐ์ผ๋ฉฐ ์ ์ฒด ์์คํ
์ง์ฐ์๊ฐ์ 40% ์์ค์ผ๋ก ๋จ์ถ์์ผฐ๋ค.DRAM's scaling technology has reached its limit and several next-generation memory technologies have been proposed to replace DRAM. Among them, phase change memory (PCM) stores data as resistance changes through phase changes in matter, enabling effective scaling. To access PCM, PCM controller converts logical address to physical address. When an address conversion request occurs, DRAM is accessed to receive address conversion data. Continuous memory access for address translation causes overall performance degradation. Prefetcher can solve these problems effectively. For PCM workloads, forward sequential patterns and reverse sequential patterns are the main ones. Some non-sequential patterns have associations with sequential patterns that exist within PCM workloads. For these non-sequential patterns, no distinct pattern exists, and successful prefetching cannot be carried out with existing prefetch algorithms. Prefetcher proposed in this work can efficiently detect sequential patterns by taking a similar approach to stream prefetcher. Furthermore, the endurance and depth parameters allow a prefetch hit to occur for patterns that no distinct pattern exists but are associated with sequential patterns in the workload. The proposed prefetcher showed more than 7% improvement in overall system performance compared to the existing prefetch algorithm. It also reduced address translation time to 17% and overall system latency to 40% compared to the case of not proceeding prefetch.์ 1 ์ฅ ์ ๋ก 1
์ 1 ์ ์ฐ๊ตฌ์ ๋ฐฐ๊ฒฝ 1
์ 2 ์ ์ฐ๊ตฌ์ ๋ด์ฉ 2
์ 3 ์ ๋
ผ๋ฌธ์ ๊ตฌ์ฑ 3
์ 2 ์ฅ ๊ด๋ จ ์ฐ๊ตฌ 5
์ 1 ์ Stream Prefetcher 5
์ 2 ์ Signature Path Prefetcher 6
์ 3 ์ Variable Length Delta Prefetcher 8
์ 3 ์ฅ ์ ์ ๋ฐฉ๋ฒ ๋ฐ ๊ตฌํ 12
์ 1 ์ ํจํด ๋ถ์ 12
์ 2 ์ ์ ์ ๋ฐฉ๋ฒ 18
์ 3 ์ ๊ตฌํ ๋ฐฉ๋ฒ 20
์ 4 ์ฅ ์ค ํ 28
์ 1 ์ ์คํ ํ๊ฒฝ ๋ฐ ๊ตฌ์ฑ 28
์ 2 ์ ์คํ ๊ฒฐ๊ณผ 31
์ 5 ์ฅ ๊ฒฐ ๋ก 48
์ฐธ๊ณ ๋ฌธํ 49
Abstract 53์
ATSC 3.0 ๋ฐ MBMS ์์คํ ๋ถ์๊ณผ ATSC 3.0์ ์ํ LDM ๊ธฐ๋ฐ ์ต์ ์ ์ก ๋ฐ MIMO ๊ธฐ๋ฐ ๊ฒ์ถ ์ฑ๋ฅ ํฅ์ ๋ฐฉ๋ฒ
์ต๊ทผ, ํต์ ์์คํ
๊ณผ ๋ฏธ๋์ด ์ฐ์
์ ๋ฐ์ ์ผ๋ก ์ธํด, ์ค๋งํธํฐ์ ์ด์ฉํ ๋ฏธ๋์ด ์๋น์ค์ ์๋น๊ฐ ๊ธ์ฆํ๊ณ ์๋ค. ํนํ, OTT (over the top)์ ๊ฐ์ ํ๋ซํผ์ ์ธ๊ธฐ๋ก ์ธํด, ๋ ๋์ ํ์ง์ ๋น๋์ค/์ค๋์ค ์๋น์ค์ ๋ํ ์์๊ฐ ์ฆ๊ฐํ๊ณ ์๋ค. ์ด๋ฌํ ์ถ์ธ์ ๋ฐ๋ผ, ๊ณ ์ฉ๋์ ์๋น์ค๋ฅผ ์์ ์ ์ด๊ณ ํจ์จ์ ์ผ๋ก ์ ์กํ ์ ์๋ ์ฐจ์ธ๋ ๋ฐฉ์ก ๊ท๊ฒฉ์ ๋ํ ํ์์ฑ์ด ๋๋๋๊ณ ์๋ค. ์ด๋ฌํ ์๊ตฌ๋ฅผ ๋ง์กฑํ๊ธฐ ์ํด, ATSC (Advanced Television Systems Committee) 3.0๊ณผ 5G MBMS (fifth-generation multimedia broadcast/multicast service) ๋ฑ์ด ์ต๊ทผ์ ๊ฐ๋ฐ๋์๋ค. ๋ณธ ํ์๋
ผ๋ฌธ์์๋ ATSC 3.0๊ณผ 5G MBMS์ ์์คํ
๋ฐ ์์ ์ฑ๋ฅ์ ๋ถ์ํ๊ณ , ATSC 3.0 ๊ธฐ๋ฐ์ LDM (layered-division multiplexing)์ ํ์ฉํ ๋ค์ค ์๋น์ค์ ์ต์ ์ ์ก ๋ฐ MIMO (multiple-input multiple-output)๋ฅผ ํ์ฉํ ๊ฒ์ถ ์ฑ๋ฅ ํฅ์ ๋ฐฉ๋ฒ์ ์ ์ํ๋ค.
๋จผ์ , ATSC 3.0๊ณผ 5G MBMS์ ์์คํ
๋ถ์ ๋ฐ ์ฑ๋ฅ ํ๊ฐ๋ฅผ ์ํํ๋ค. ATSC 3.0๊ณผ 5G MBMS ์ ํธ๋ฅผ ๊ฐ๊ฐ ๋ฐ์ดํฐ ์์ญ (data part)๊ณผ ์ ์ด ์์ญ (control part)์ ํด๋นํ๋ ๋ฌผ๋ฆฌ ์ฑ๋๋ก ๋๋๊ณ , ๊ฐ ์ ํธ ์์ญ์ ๋ํด ๋
๋ฆฝ์ ์ผ๋ก ์ฑ๋ฅ ํ๊ฐ๋ฅผ ์ํํ๋ค. ๋ํ, ๋ค์ํ ์์ ์ฑ๋ฅ ๋ถ์์ ์ํด, ๋ฐฉ์ก๋ง๊ณผ ๊ฐ์ด ๋งค์ฐ ๋์ ์ปค๋ฒ๋ฆฌ์ง (coverage)์์ ๋ฐ์ํ ์ ์๋ ๋งค์ฐ ๊ธด ์ง์ฐ (delay)์ ํฌํจํ ์ด๋ ๋ฐ ๊ณ ์ ์ฑ๋ ํ๊ฒฝ์ ๊ณ ๋ คํ๊ณ , ์ด์์ ์ธ ์ฑ๋ ์ถ์ ์ ํฌํจํ ์ฑ๋ฅ์ด ๋ค๋ฅธ 3๊ฐ์ง ์ฑ๋ ์ถ์ ๋ฐฉ๋ฒ์ ์ ์ฉํ๋ค. ์ ์ฐ ์คํ ๊ฒฐ๊ณผ๋ ๋ฐ์ดํฐ ์์ญ๊ณผ ์ ์ด ์์ญ ๋ชจ๋์์ ATSC 3.0์ด 5G MBMS์ ๋นํด ์๋นํ ์ฑ๋ฅ ์ด๋์ ์ป์ ์ ์๊ณ , ATSC 3.0์ด 5G MBMS ๋ณด๋ค ํจ์จ์ ์ธ ๋ฐฉ์ก๋ง ๊ตฌ์ถ์ ์ ๋ฆฌํ๋ค๋ ๊ฒ์ ๋ณด์ฌ์ค๋ค. ๋ํ, ์ฐจ์ธ๋ ๋ฐฉ์ก ๊ท๊ฒฉ์ธ NR MBS (new radio multicast and broadcase service)๋ 5G MBMS์ ๋นํด BICM (bit interleaved coded modulation)์ด ๊ฐ์ ๋์๊ธฐ ๋๋ฌธ์ ํฅ์๋ ์ฑ๋ฅ์ ์ป์ ์ ์๋ค. ๊ทธ๋ฌ๋, ๋์ ์๋์์๋ ์ฌ์ ํ ๋ํ๋ฌ (Doppler)์ ์ํ ์ฑ๋ฅ ์ดํ๊ฐ ๋ฐ์ํ๊ธฐ ๋๋ฌธ์, ATSC 3.0์ ์ธํฐ๋ฆฌ๋น (interleaving)๊ณผ ๊ฐ์ ์ถ๊ฐ์ ์ธ ๋ค์ด๋ฒ์ํฐ (diversity) ์ด๋์ ์ป์ ์ ์๋ ๋ฐฉ๋ฒ์ ์ถ๊ฐ๋ก ์ ์ฉํจ์ผ๋ก์จ, ๋์ ์๋์์ ๋์ฑ ๊ฐ์ ๋ ์ฑ๋ฅ์ ์ป์ ์ ์๊ณ , ๋ฐ๋ผ์ ๋ฐฉ์ก๋ง์์ ํฅ์๋ ์ ์ก ํจ์จ์ ์ป์ ์ ์์ ๊ฒ์ผ๋ก ์์ํ ์ ์๋ค.
๋ํ, ATSC 3.0 ์์คํ
์ ๊ธฐ๋ฐ์ผ๋ก ํ ๋ฐฉ์ก๋ง์ ์ ์ก ํจ์จ์ ๊ทน๋ํํ๊ธฐ ์ํ ๋ ๊ฐ์ง ๊ฐ์ ๋ฐฉ๋ฒ์ ์ ์ํ๋ค. ์ฒซ ๋ฒ์งธ๋ก, LDM์ ๊ธฐ๋ฐ์ผ๋ก ํ ๋ค์ค PLP (physical layer pipe)์ ์ต์ ์ ์ก ๋ฐฉ๋ฒ์ ์ ์ํ๋ค. ๊ท๊ฒฉ์ ํ์ฅํ์ฌ ์ต๋ 4๊ฐ PLP์ 4๊ฐ ๊ณ์ธต (layer)๊น์ง ๊ณ ๋ คํ LDM ๊ธฐ๋ฐ M-PLP (multiple-PLP) configuration๋ค์ ์ฑ๋ ์ฉ๋ (channel capacity) ๋ถ์๊ณผ ์์ ์ฑ๋ฅ ํ๊ฐ๊ฐ ์ํ๋๋ค. LDM์ ๋ค๋ฅธ ์ง๊ต ๋ค์คํ (orthogonal multiplexing) ๋ฐฉ๋ฒ์ ๋นํด ์ต์ ์ฑ๋ ์ฉ๋์ ์ต๋ํํ๋ ๊ด์ ์์ ๋ ๋์ ์ ์ก ํจ์จ์ ์ป์ ์ ์๋ค. ์ ์ฐ ์คํ ๊ฒฐ๊ณผ๋ ๊ฐ PLP๋ฅผ ๊ฐ ๊ณ์ธต์ ํ ๋นํ๋ ๋ค๊ณ์ธต LDM์ ๊ฒฝ์ฐ๊ฐ ๋๋จธ์ง ๋ค์คํ ๋ฐฉ๋ฒ์ ๋นํด ๊ฐ์ฅ ๋์ ์ฑ๋ ์ฉ๋๊ณผ ๊ฐ์ฅ ์ข์ ์์ ์ฑ๋ฅ์ ๋ฌ์ฑํ ์ ์์์ ๋ณด์ฌ์ค๋ค. ๋ํ, LTDM (layered time-division multiplexing)์ ์ฑ๋ฅ ์ดํ๊ฐ ๋ค๊ณ์ธต LDM์ ๋นํด ํฌ์ง ์์ผ๋ฏ๋ก, LTDM ๋ํ ํจ์จ์ ์ธ ์ ์ก์ ์ํ ์ข์ ์๋ฃจ์
์ด ๋ ์ ์์์ ๋ณด์ฌ์ค๋ค.
๋ง์ง๋ง์ผ๋ก, ๋ฐฉ์ก๋ง์ ์ ์ก ํจ์จ ๊ฐ์ ์ ์ํ ๋ ๋ค๋ฅธ ๋ฐฉ๋ฒ์ผ๋ก์ MIMO ์์คํ
์์์ ๊ฒ์ถ ์ฑ๋ฅ ํฅ์ ๋ฐฉ๋ฒ์ ์ ์ํ๋ค. ATSC 3.0์ MIMO ์์คํ
์ MIMO precoding ๋ด I/Q polarization interleaving์ ๋น์ ํ ๋์์ผ๋ก ์ธํด ์ฐ์ ๊ฐ์ญ ์ ๊ฑฐ (successive interference cancellation: SIC) ๊ธฐ๋ฐ ๋ฐฉ๋ฒ์ ์ ์ฉ์ด ๋ถ๊ฐ๋ฅํ๋ค. ๋ฐ๋ผ์, SIC ๊ธฐ๋ฐ์ ์ค์ต์ (suboptimal) ๊ฒ์ถ ๋ฐฉ๋ฒ์ ์ฝ๊ฒ ์ ์ฉํ ์ ์๋๋ก, ์์ ์ ํธ์ ๋ํด ๋ค๋ฅธ ํํ์ real-valued representation์ ์ ์ํ๋ค. ๋ํ, ์ฑ๋ฅ ๊ฐ์ ๊ณผ ๋ณต์ก๋ ๊ฐ์๋ฅผ ์ํด ATSC 3.0์์ ์ฌ์ฉ๋๋ 2D NUC (two-dimensional non-uniform constellation)์ ๊ตฌ์กฐ์ ํน์ง์ ๋ฐ์ํ ๋ธ๋ก ๋จ์์ -best ์๊ณ ๋ฆฌ์ฆ ๊ธฐ๋ฐ ๊ฒ์ถ ๋ฐฉ๋ฒ์ ์ ์ํ๋ค. ์ ์ฐ ์คํ ๊ฒฐ๊ณผ๋ ๊ณ ์ ๋ฐ ์ด๋ ์ฑ๋ ํ๊ฒฝ์์ ์ ์ํ๋ ๋ฐฉ๋ฒ์ด ๊ธฐ์กด ์ ํ ํํฐ๋ฅผ ์ ์ฉํ ๋ฐฉ๋ฒ์ ๋นํด ๋ณต์ก๋๋ ์ฝ๊ฐ ์ฆ๊ฐํ์ง๋ง, ๋งค์ฐ ํฅ์๋ ์ฑ๋ฅ์ ์ป์ ์ ์์์ ๋ณด์ฌ์ค๋ค. ๋ํ, ์ ์ํ๋ ๋ฐฉ๋ฒ์์ ์ ์ ํ ํ๋ณด ์ฌ๋ณผ์ ๊ฐ์๋ฅผ ์ ํํจ์ผ๋ก์จ ์ข์ ์ฑ๋ฅ-๋ณต์ก๋ trade-off๋ฅผ ๋ง์กฑํ ์ ์์์ ๋ณด์ฌ์ค๋ค.|Recently, with the development of communication systems and the media industry, the consumption of media services using smartphones has rapidly increased. In particular, owing to the popularity of media platforms, such as over the top (OTT), the demands for higher-quality video/audio services have increased. To satisfy the requirements, Advanced Television Systems Committee (ATSC) 3.0 and fifth-generation (5G) multimedia broadcast/multicast service (MBMS) have been recently developed as next-generation terrestrial broadcasting standards. To realize an efficient broadcasting network, the system and reception performance of ATSC 3.0 and 5G MBMS are analyzed. Furthermore, to maximize the transmission efficiency in broadcasting networks, an optimal transmission scheme of multiple services using layered-division multiplexing (LDM) and an improved detection scheme using multiple-input multiple-output (MIMO) are proposed based on the ATSC 3.0 system.
First, system analysis and performance evaluation of ATSC 3.0 and 5G MBMS are performed. The ATSC 3.0 and 5G MBMS signals can be divided into several physical channels corresponding to the data and control parts. Subsequently, the reception performance is evaluated independently for the physical channels corresponding to each part. In addition, as channel environments, mobile and fixed channels with very long delay spread, which may occur in very wide coverage for broadcasting networks, are considered. Moreover, three channel estimation schemes corresponding to ideal, low-complexity, and practical estimation are applied. The simulation results show that ATSC 3.0 can obtain significant performance gain compared to 5G MBMS in both the data and control parts. Therefore, ATSC 3.0 is more advantageous than 5G MBMS for efficient broadcasting networks. In addition, 5G-based new radio (NR) multicast and broadcast service (MBS), which is considered as a next-generation broadcasting standard, can obtain improved performance by using enhanced bit-interleaved coded modulation (BICM) compared to 5G MBMS. However, to obtain additional performance gain under higher mobile speeds, it is necessary to apply the schemes such as interleaving used in ATSC 3.0.
Furthermore, two improved schemes aimed to maximize of transmission efficiency are proposed based on the ATSC 3.0 system. First, an optimal transmission scheme of multiple physical layer pipes (M-PLPs) based on LDM is presented. Considering up to 4 PLPs and four layers based on LDM extension, the capacity analysis and performance evaluation of LDM-based M-PLP configurations are performed. LDM can provide higher transmission efficiency from the perspective of maximizing the minimum rate than other orthogonal multiplexing schemes. The simulation results show that multi-layer LDM, which allocates each PLP to each layer, can achieve the highest capacity and best reception performance compared to other configurations. In addition, since the performance degradation of layered time-division multiplexing (LTDM) is not significant compared to the multi-layer LDM, it is shown that LTDM may also be a good solution for the efficient transmission of M-PLPs.
Finally, as another improvement of the broadcasting network, an improved detection scheme for the ATSC 3.0 MIMO system is proposed. The MIMO system of ATSC 3.0 cannot use the successive interference cancellation (SIC)-based scheme owing to the non-linear operation of I/Q polarization interleaving in the MIMO precoding. Therefore, this thesis presents an alternative approach to the real-valued representation for the received signal to facilitate a simpler application of various SIC-based detection schemes than other forms of real-valued representations. In addition, to improve the detection performance and complexity, an improved detection scheme using -best algorithm based on block cancellation, which reflects the structural property of two-dimensional non-uniform constellation (2D NUC) defined in ATSC 3.0, is proposed. The simulation results show that the proposed detection scheme outperforms the linear detection under mobile and fixed channels, although the complexity increases slightly. Furthermore, a good performance- complexity trade-off can be satisfied by selecting the appropriate number of candidate symbols for the proposed detection scheme.1. Introduction 1
1.1 Problems and Related Previous Works 6
1.2 Summary of Contributions 11
2. Study on ATSC 3.0 and 5G MBMS Systems 14
2.1 Structure of ATSC 3.0 System 16
2.2 Structure of 5G MBMS System 22
2.3 Simulation Results 31
2.4 Summary 49
3. Optimization of LDM-Based Transmission for ATSC 3.0 51
3.1 LDM-Based M-PLP Configuration in ATSC 3.0 52
3.2 Extension to Multi-Layer LDM 57
3.3 Capacity Analysis for LDM-Based M-PLP Configurations 66
3.4 Simulation Results 70
3.5 Summary 87
4. Improved Detection Scheme of ATSC 3.0 MIMO 88
4.1 ATSC 3.0 MIMO System 89
4.2 Real-Valued Representation of Received Signals 93
4.3 Improved SIC-Based Detection Scheme 96
4.4 Simulation Results 105
4.5 Summary 111
5. Conclusions 112Docto
์๋น์ฌํ์ ๊ธฐํธ(่จ่)์ ์ด๋ฏธ์ง์ ํด์์ ํตํ ํํ์ ์ฐ๊ตฌ : ๋ณธ์ธ์ ์ํ์ ์ค์ฌ์ผ๋ก
ํ์๋
ผ๋ฌธ(์์ฌ)--์์ธ๋ํ๊ต ๋ํ์ :์์ํ๊ณผ ์์ํ์ ๊ณต,1999.Maste
New Security Rights on Movables and Claims: An Overview
์ฐ๋ฆฌ ๋ฒ์ ์์ ํ์ฉํ ์ ์๋ ๋์ฐใ์ฑ๊ถ๋ด๋ณด๋ก์๋ ๋ฏผ๋ฒ์ด ์ ํ๋ ์ง๊ถ(๋ฏผ๋ฒ ์ 329์กฐ, ์ 345์กฐ)๊ณผ ๊ฑฐ๋๊ณ์์ ๋ฐ๋ฌํด์จ ์๋๋ด๋ณด๊ฐ ์กด์ฌํ๋ค. ๊ทธ๋ฐ๋ฐ ์ฃผ์งํ๋ ๋ฐ์ ๊ฐ์ด ์ง๊ถ๊ณผ ์๋๋ด๋ณด๋ ๊ทธ๊ฒ์ ๊ฒฝ์ํ ์ ์๋ ์๊ธฐ๋ฅ์๋ ๋ถ๊ตฌํ๊ณ ๊ฑฐ๋๊ณ์ ์์์ ๋น์ถ์ด ๋ถ์ถฉ๋ถํ ๋จ์ ๋ค์ด ์๋ค๊ณ ์ง์ ๋์ด ์๋ค. ์ด๋ฌํ ๋์ฐโ
์ฑ๊ถ๋ด๋ณด์์์ ๋ฌธ์ ์ ์ ๋์ฒํ๊ธฐ ์ํด ์ ์ ๋ ๋ฒ๋ฅ ์ด ๏ฝข๋์ฐโ
์ฑ๊ถ ๋ฑ์ ๋ด๋ณด์ ๊ดํ ๋ฒ๋ฅ ๏ฝฃ (2010๋
6์ 10์ผ, ๋ฒ๋ฅ ์ 10366ํธ)์ด๋ค. ๋๋ฒ์ ๋์ฐโ
์ฑ๊ถ์ ๋ชฉ์ ์ผ๋ก ํ๋ ์๋ก์ด ๋ด๋ณด๋ฌผ๊ถ์ ์ฐฝ์คํ๊ณ ์ด๋ฅผ ๋ฑ๊ธฐํ์ฌ ๊ณต์ํ ์ ์๋๋ก ํ๋ค. ์ด ๊ธ์ ๏ฝข๋์ฐโ
์ฑ๊ถ ๋ฑ์ ๋ด๋ณด์ ๊ดํ ๋ฒ๋ฅ ๏ฝฃ์ ๋ฐ๋ผ ์ฐ๋ฆฌ ๋ฒ์ ์ ๋์
๋ ๋์ฐ๋ด๋ณด๊ถ๊ณผ ์ฑ๊ถ๋ด๋ณด๊ถ ์ ๋์ ๊ตฌ์ฒด์ ์ธ ๋ด์ฉ์ ๊ฐ๊ดํ๊ณ , ๊ทธ ์ ์ฉ์์ ์ ๊ธฐ๋ ์ ์๋ ๋ช ๊ฐ์ง ๋ฒ๋ฅ ๋ฌธ์ ๋ค์ ๋ํด ์๋ก ์ ์ธ ํด์๋ก ์ ์๊ฐํด ๋ณด๋ ๊ฒ์ ๋ชฉ์ ์ผ๋ก ํ๋ค. ๋์์ ์ด๋ฌํ ๋ด์ฉ์ ๋ฐํ์ผ๋ก ๋๋ฒ์ด ๋์
ํ๋ ๋ฑ๊ธฐ๋ด๋ณด๊ถ์ ์ฅ๋จ์ ์ ํ๊ฐํ๋ค
์์ฑDMB์ฌ์ ์ ์ฑ ๊ฒฐ์ ์ฌ๋ก ์ฐ๊ตฌ
ํ์๋
ผ๋ฌธ(์์ฌ) --์์ธ๋ํ๊ต ๋ํ์ :ํ์ ํ๊ณผ(์ ์ฑ
ํ์ ๊ณต),2008.Maste
๋ฐฉ๊ด์์ ๋ํ ๊ฒฝ์๋ ์ ์ ๊ฒ์ฒด์์ ๊ด์ฐฐ๋๋ ์ํ ํ๊ด ์นจ์ค์ ์ ํ ์ข ์ ๋ณ๊ธฐ ์์น๊ณผ ์์กด๊ณผ์ ๊ด๋ จ์ฑ :
ํ์๋
ผ๋ฌธ (์์ฌ)-- ์์ธ๋ํ๊ต ๋ํ์ : ์ํ๊ณผ ๋น๋จ๊ธฐ๊ณผํ ์ ๊ณต, 2016. 2. ๊ตฌ์ํ.Objectives: This study aimed to elucidate the relationship between lymphovascular invasion (LVI) at transurethral resection of bladder tumor (TURBT) and the risk of pathological upstaging as well as the clinical outcomes.
Materials and Methods: PubMed, SCOPUS, Web of Science and Cochrane Library databases were searched from the respective dates of inception until November 11, 2013.
Results: A total of 16 articles met the eligibility criteria for this systematic review, which included a total of 3,905 patients. LVI was detected in 18.6% in TURBT specimens. The significant association was found between LVI at TURBT and pathological upstaging of bladder cancer (odds ratio 2.21, 95% confidence interval [CI] 1.44-3.39) without heterogeneity (I2 45%, p = 0.14). The pooled hazard ratio (HR) was statistically significant for recurrence-free survival (HR 1.47, 95% CI 1.24-1.74), progression-free survival (HR 2.28, 95% CI 1.45-3.58), and disease-specific survival HR, 1.3595% CI, 1.01-1.81), but not overall survival (HR, 1.5595% CI, 0.90-2.67). Tests of inconsistency for disease-specific survival (I2 66%, p = 0.007) and overall survival (I2 72%, p = 0.03) could not exclude a significant heterogeneity. The results of Beggs and Eggers test showed that there was evidence of publication bias on pathological upstaging and progression-free survival.
Conclusions: The data obtained in this meta-analysis indicate that the presence of LVI at TURBT portends the increased risk of pathological upstaging and may provide additional prognostic information. However, a large, well-designed, prospective study is needed to investigate potential treatment options for bladder cancer with LVI.์ ๋ก 1
์คํ ์ฌ๋ฃ ๋ฐ ๋ฐฉ๋ฒ 3
๊ฒฐ ๊ณผ 6
๊ณ ์ฐฐ 23
๊ฒฐ ๋ก 26
์ฐธ๊ณ ๋ฌธํ 27
์ด ๋ก (๊ตญ ๋ฌธ) 32Maste
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