EDISON Co-rotational Plane Beam-Dynamic Tip Load를 이용한 가진주파수 변화에 따른 외팔보의 자유단 진동 연구

박철우,주현식,류한열,신상준,Park, Chul-Woo,Joo, Hyun-Shig,Ryu, Han-Yeol,Shin, Sang-Joon 한국전산구조공학회 2015 한국전산구조공학회논문집 Vol.28 No.5

본 논문에서는 Euler-Bernoulli Beam(EB-beam) 및 신속 Fourier 변환을 이용하여 수치분석적 빔 모델 및 Co-rotational plane beam EDISON program(CR-beam)을 이용한 빔 모델의 가진주파수 변화에 따른 외팔보의 자유단 진동 연구를 수행하였다. 위의 두 빔 모델에서의 끝단에서는 진동이 시간이 지남에 따라 감소하다가 정상상태에 이르는 것을 확인하였다. 끝단에서 가진주파수가 증가함에 따라 구조적 감쇠에 의해 변위이 감소하는 경향을 보인다. 감쇠를 고려한 EB-beam과 CR-beam가 정상상태로 진입하는 경향이 비슷하나, 가진주파수는 정상상태가 나타나는 시간과 독립적임을 제시한다. In this paper, Euler-Bernoulli beam theories(EB-beam) are used, and Fast Fourier Transformation(FFT) analysis is then employed to extract their natural frequencies using both analytical approach and Co-rotational plane beam(CR-beam) EDISON program. EB-beam is used to analyze a spring-mass system with a single degree of freedom. Sinusoidal force with various frequencies and constant magnitude are applied to tip of each beam. After the oscillatory tip response is observed in EB-beam, it decreases and finally converges to the so-called 'steady-state.' The decreasing rate of the tip deflection with respect to time is reduced when the forcing frequency is increased. Although the tip deflection is found to be independent of the excitation frequency, it turns out that time to reach the steady state response is dependent on the forcing frequency.

몬테 카를로 시뮬레이션을 통한 발사관 구조 안전성 분석

박철우,이온수,신효섭,박진용,이동주,Park, Chul-Woo,Lee, Onsoo,Shin, Hyo-Sub,Park, Jin-Yong,Lee, Dong-Ju 한국시뮬레이션학회 2018 한국시뮬레이션학회 논문지 Vol.27 No.4

Launching system is designed to store the payload, withstand the rigors, and prevent it from rusting and damaging. The behavior during initial deployment of the missile is determined by production, assembly and insertion condition of a launching tube and a missile. The purpose of this research is to confirm the safety of a launching tube by statistically analyzing behavior of the missile, during initial deployment stage. Error parameters which effect initial behavior of the missile are selected and analyzed through Monte-Carlo Simulation. Based on the result of simulation, tip-off and stress distribution between rail and shoe is predicted by using the commercial analysis program called Recurdyn. Lastly, the safety factor is calculated based on yield strength of the material and maximum stress of the rail during the process of launching. The safety of the launching system is verified from the result of the safety factors. 발사관은 탑재물을 보관하고 외부 환경으로부터 부식 및 파손되는 것을 방지하는 역할을 한다. 발사관과 유도탄의 제작, 조립 그리고 장입 상태에 따라 발사할 때 유도탄의 초기 거동을 결정하게 된다. 본 연구의 목적은 유도탄이 발사관에서 사출될 때 유도탄의 초기 거동을 결정하는 요소를 통계적으로 분석하여 발사관의 안전성을 확인하는 것이다. 유도탄이 발사될 때 거동에 영향을 주는 오차 요소들을 선정한 후 Monte-Carlo 시뮬레이션을 수행하여 통계적으로 분석하였다. 시뮬레이션 결과를 바탕으로, 각 오차 요소들을 고려한 다물체 동역학 해석을 상용프로그램인 Recurdyn을 이용하여 동역학 해석을 수행하여 유도탄 발사할 때 발생하는 중력 침하 및 레일과 슈 사이에 발생하는 응력을 구하였다. 해당 결과를 바탕으로 현재 설계된 발사관에 대한 안전성을 검증하였다.

강유전 고분자 박막의 상전이 특성

박철우,정치섭,Park, Chul-Woo,Jung, Chi-Sup 한국전기전자재료학회 2014 전기전자재료학회논문지 Vol.27 No.2

Phase transition properties of the copolymer films of polyvinylidene fluoride (PVDF) and trifluoroethylene(TrFE), P(VDF-TrFE), were studied with X-ray diffraction (XRD) and polarization modulated ellipsometry (PME). XRD studies on both Langmuir-Blodgett (LB) films and spin coated films exhibit conversions from ferroelectric phase to paraelectric phase at $108{\pm}2^{\circ}C$ on heating and paraelectric phase to ferroelectric phase at $78{\pm}2^{\circ}C$ on cooling. The presence of the ferroelectric-paraelectric phase transition is also confirmed by the PME technique for the first time in this study. PME was proved to be a very sensitive tool in the measurement of the structural changes at the nano-thickness films.

강유전 고분자 박막의 저차원 전기광학 특성

박철우,정치섭,Park, Chul-Woo,Jung, Chi-Sup 한국전기전자재료학회 2014 전기전자재료학회논문지 Vol.27 No.3

The electro-optic properties in Langmuir Blodgett films of poly (vinylidene fluoride trifluoroethylene) are investigated in the crossover region between two and three dimensions. The absence of finite size effect is observed in the films thinner than 20 nm, which confirms that these films are two dimensional ferroelectrics. The copolymer LB film of P(VDF-TrFE) exhibits the largest electro-optic response(26 pm/V) at 10 layer thickness. The cross-over behavior of electro-optic effect around the 10 layer thickness was discussed with the formation of nanomesa after thermal annealing.

3단 구성의 디지털 DLL 회로

박철우,강진구,Park, Chul-Woo,Kang, Jin-Ku 한국전기전자학회 2002 전기전자학회논문지 Vol.6 No.1

본 논문에서는 전부 디지털 회로로 구성된 고 해상도의 DLL(Delay Locked Loop)를 제안하였다. 제안된 회로는 위상 검출기, 지연 선택 블록, 그리고 각각의 지연 체인을 가지는 Coarse, Fine 그리고 Ultra Fine 위상조정 블록의 삼 단의 형식으로 되어 있다. 첫 번째 단은 Ultra Fine 위상조정블록으로 고 해상도를 얻기 위하여 Vernier Delay Line을 사용하였다. 두 번째와 세 번째 단은 Coarse와 Fine 위상조정블록으로 각각의 단위 지연 체인을 이루는 단위 지연 소자의 해상도 만큼의 위상 제어를 하게 되며, 두 단은 상당히 비슷한 구조를 이루고 있다. 회로는 HSPICE를 이용하여 공급 전압이 3.3V인 $0.35{\mu}m$ CMOS 공정으로 시뮬레이션 되었다. 시뮬레이션 결과 회로의 해상도를 약 10ps로 높일 수 있었으며, 동작 범위는 250MHz에서 800MHz 이다. This paper describes a high resolution DLL(Delay Locked Loop) using all digital circuits. The proposed architecture is based on the three stage of coarse, fine and ultra fine phase tuning block which has a phase detector, selection block and delay line respectively. The first stage, the ultra fine phase tuning block, is tune to accomplish high resolution using a vernier delay line. The second and third stage, the coarse and fine tuning block, are tuning the phase margin of Unit Delay using the delay line and are similar to each other. It was simulated in 0.35um CMOS technology under 3.3V supply using HSPICE simulator. The simulation result shows the phase resolution can be down to lops with the operating range of 250MHz to 800MHz.

3상 위상제어 정류기를 위한 DVR의 반응시간 최적화

박철우(Chul-Woo Park),정수경(Sookyoung Joung),류지열(Jee-Youl Ryu),이대섭(Dae-seup Lee) 제어로봇시스템학회 2013 제어·로봇·시스템학회 논문지 Vol.19 No.3

In this paper, we present optimization technique for the response time of DVR (Dynamic Voltage Restorer) and the possible compensation range of voltage dip by the DVR system. To protect 3-phase phase-controlled rectifier from voltage dip, DVR system needs to have optimum response time as an important design factor. Although the fast response time of DVR ensures wider range of voltage dip, DVR controller has so high cost and poor stability. This paper proposes DVR system with optimum response time required for certain intensity of voltage dips and good stability to support possible compensation range of voltage dip. Proposed technique showed optimum response time and good stability for overall system. We believe that proposed technique is reliable and useful in DVR design.

군사용 소형 무인항공기(25~150Kg) 감항인증(안전성인증) 기술기준 개발에 관한 연구

박철우(Chul-Woo Park),김성훈(Seong-Hun Kim),이원희(Won-Hi Lee),신승주(Seung-Ju Shin) 한국항공우주학회 2023 한국항공우주학회 학술발표회 논문집 Vol.2023 No.11

트럭용 브레이크페달의 사출성형해석에 관한 연구

박철우(Chul woo Park) (사)한국CDE학회 2012 한국 CAD/CAM 학회 학술발표회 논문집 Vol.2012 No.2

Injection molding process one of the most important methods to produce plastic parts with high efficiency and low cost. Today, Injection molded parts have been increased dramatically the demand for high strength and quality applications. In this study, truck brake pedal is made of Cast iron and plastic materials to replace the frame for the optimization process that minimizes the runner and the gate dimension will determine the size and shape. Runner and gate dimensions of change based on availability of the product. I will discuss the injection molding. This report investigates that the optimum injection molding condition for minimum of runner and gate position. The FEM Simulation CAE tool, MOLDFLOW, is used for the analysis of injection molding process.

라인 레이저를 이용한 수술기기 삽입 유도 시스템의 제어 방법

박철우(Chul-Woo Park),박일형(Il-Hyung Park),정상현(Sanghyun Joung) 한국정보기술학회 2018 한국정보기술학회논문지 Vol.16 No.5

In orthopedic surgery, the medical staff determines the insertion position and direction of the surgical instrument, depending on the 2D fluoroscopic images taken with the C-arm and the clinical experience. Such a surgical technique is not only difficult to accurately treat, but also causes medical staff to experience radiation exposure problems. In this paper, we propose a system and a control method to indicate insertion position and direction of surgical instruments by attaching two line laser projection devices to C-arm head. In the proposed system, if the insertion position and direction of the surgical instrument are specified, two line lasers are projected on the lesion to guide the insertion position and direction of the surgical instrument. The medical staff can insert the surgical instrument such as the fixing screw in the position and direction guided by the line laser, so that it can be treated more quickly and accurately than the existing surgical method. The surgical instrument insertion guiding system proposed in this paper can reduce the radiation dose of the medical staff and reduce the operation time, which can contribute to the recovery of the patient.

국어 분열문의 통사구조

박철우 ( Chul Woo Park ) 한말연구학회 2008 한말연구 Vol.- No.22