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정성구,김성욱,정연득,김응태,Jung, Sunggoo,Kim, Sung-Yug,Jung, Yeundeuk,Kim, Eung-Tai 한국항공운항학회 2015 한국항공운항학회지 Vol.23 No.4
Quadrotor is widely used in variable application nowadays. Due to its inherent unstable characteristics, control system to augment the stability is essential for quadrotor operation. To design control system and verify its performance through simulation, accurate dynamic model is required. Quadrotor dynamic model is simply compared with conventional rotorcraft such as helicopter. However, the accurate dynamic model of quadrotor is not easy to develop because of the highly correlated aerodynamic effect of each rotor. In this paper, quadrotor dynamic model is identified from the flight data using frequency domain approach. Flight test of quadrotor is performed in closed loop configuration with stability augmentation system included. Frequency sweep input is applied in each of lateral, longitudinal, yaw and heave axis separately. The bare dynamic model is identified from the flight data of quadrotor responses and thrust measurement through Pulse Width Modulation(PWM) data. The frequency responses of identified model match well with those of flight data, and time responses of identified model for doublet input in each axis are also shown to agree with flight data.
헬리콥터 선형모델 식별을 위한 off-axis 입력 설계
정성구(Sung-Goo Jung),김응태(Eung-Tai Kim) 한국산학기술학회 2015 한국산학기술학회 학술대회 Vol.2015 No.1
본 논문에서는 헬리콥터의 선형 모델 식별을 위하여 사용되는 주파수 sweep 기법에 대해 알아보고, off-axis 조종입력의 입력신호에 따른 식별 성능에 대해 연구하였다. 헬리콥터의 비선형 모델을 사용하여 주파수 sweep을 수행하였으며, 횡방향에 대해서만 고려하였다.
70% 간절제술을 받은 쥐에서 피브린젤을 이용한 중간엽줄기세포의 생체내 간세포 분화
신우영(Woo Young Shin),정성은(Sung Eun Jung),민혜숙(Hye Sook Min),이해원(Hae Won Lee),조응호(Eung-Ho Cho),이남준(Nam-Joon Yi),서경석(Kyung-Suk Suh),이건욱(Kuhn Uk Lee) 한국간담췌외과학회 2010 한국간담췌외과학회지 Vol.14 No.2
Purpose: To investigate the differentiation of rat bone marrow-derived mesenchymal stem cells (MSCs) into hepatocytes by cell transplantation using fibrin gels in a 70% hepatectomized rat model. Methods: MSCs were isolated from Sprague-Dawley rats. MSCs (1.5×107 cells) were mixed with fibrin gels and injected immediately into the abdominal cavity of 70% hepatectomized rats. Fibrin-gels consisted of 500 IU/ml of thrombin and 90 mg/ml of fibrinogen. Transplanted MSCs in the fibrin scaffold were retrieved from surgically opened peritoneal cavities of rats on days 5, 10, 15, and 21 after the operation. The specimens were analyzed histologically and immunohistochemically. Results: On H&E staining, MSCs from hepatectomized rats had changed to a round shape, while MSCs of the control group kept their spindle shape. When the fibrin matrix was biodegraded at day 15, the morphology of the MSCs had changed to hepatocyte-like cells without sinusoids and the hepatocyte-like cells had formed a three-dimensional tissue permitting cell-to-cell contacts within the matrix. On immunohistochemistry, MSCs expressed the hepatocyte markers cytokeratin 18, albumin, and alpha-fetoprotein, after 15 days of transplantation. Conclusion: When bone marrow-derived MSCs are transplanted using fibrin gels in the 70% hepatectomized rat, MSCs differentiate into hepatocyte-like cells and are conglomerated so that they form three-dimensional tissue-like hepatocytes without sinusoids.
이온선 혼합에 의한 Al / Pd계의 상형성 및 전이에 관한 열역학적 연구
최정동(Jeong Dong Choi),홍진석(Jin Seok Hong),곽준섭(Joon Seop Kwak),지응준(Eung Joon Chi),박상욱(Sang Wook Park),백홍구(Hong Koo Baik),채근화(Keun Hwa Chae),정성문(Sung Mun Jung),황정남(Chung Nam Whang) 한국진공학회(ASCT) 1993 Applied Science and Convergence Technology Vol.2 No.2
Al/Pd 계에서 이온선 혼합에 의한 초기 상형성 및 상전이를 연구하기 위하여 Al(500 Å)/Pd (200 Å)/glass 이중박막을 제작하여 여러가지 이온선량으로 80 keV의 에너지를 가진 Ar^+을 주입시켰다. RBS, TEM 등을 이용하여 이온선에 의한 혼합양상 및 상분석을 행하였다. 상온에서 이온선 혼합법에 의해 초기에 형성된 Al₃Pd₂는 이온선량이 증가함에 따라 Al₃Pd₂ 뿐만 아니라 AlPd상이 형성됨을 알 수 있었다. 유효생성열 (ΔH') 개념을 이온선 혼합에 의한 상형성 및 전이에 도입하여 초기 Al₃Pd₂ 형성 및 AlPd상으로서 상전이를 예측하였으며, 이러한 예측은 실험결과와 매우 일치함을 알 수 있었다. 금속/금속계 뿐만 아니라 금속/실리콘계에 대해서 이온선 혼합에 의한 초기 상형성 및 상전이에 관한 연구 및 실험이 현재 진행 중에 있다. Evaporated Al/Pd thin films were irradiated with various doses to produce intermetallic compounds. In order to study the first phase formation and phase sequence, RBS and TEM studies have been used. It was found that the initial phase formed by irradiation of 5×10^(15)Ar^+/㎠ was Al₃Pd₂, while 1.5×10^(16)Ar+/㎠ gave the subsequent phase of AlPd. This phenomenon was analysed using effective heat of formation (ΔH') model. The experimental results agree with that predicted by effective heat of formation model. This model has been extended to predict the first phase formation and phase sequence by ion beam mixing in metal/Si systems as well as metal/metal systems.