Remotely Piloted Aircraft (RPA) controls as a type of unmanned aerial vehicle (drone) is growing rapidly and its flight controller stick disposition is required standardization. We should standardize RPA drone flight control disposition because the flight pilot of RPA is hard to be trained so the flight controller stick differences impairs safety and wastes time and effort of flight controller industry. So this study researches the on-going standardization of RPA drone flight control disposition in Korea and foreign countries. Also this paper analyzes and researches of expert about RPA drone flight controller function and application of flight control mode. I accomplished expert research about standardization plan of unmanned flight control mode and confirm the necessity. Nowadays mode1 and 2 are mostly used in Korea so I carried out preference investigation for two modes. There were 4 preferences choices of RPA drone control mode necessity (importance) and recommendation of standardization modes. They answered that necessity of standardization is important considering pilot training, flight safety and positive development of drone industry. The result of standardization mode preference is that they prefer mode 2 (drone maker 86%, training facilities and research facilities 58%, government bureau 60%). Overall preference result shows that mode 1 24%, mode 1&2 16%, mode 2 60%. So they preferred mode 2 by 60%. The differences between two modes are the direction of throttle and pitch. Direction of throttle and pitch operate opposite way. They prefer mode 2 because mode 2 has similarities of manned flight control mode. Significance of this study is that it showed the necessity of standardization and flight control preference in a quantitative way. It will help drone standardization in related industries and development direction near future.

본 연구에서는 1차 전단변형이론을 고려한 비국소 자기-전기-탄성 나노 판의 2방향 좌굴해석에 관하여 연구하였다. 면내 전기-자기-탄성 나노 판에서 전기장과 자기장은 무시할 수 있다. 자기-전기 경계조건과 맥스웰 방정식에 따라 전기-자기-탄성 나노 판의 두께 방향에 따른 자위 및 전위의 변화가 결정된다. 자기-전기-탄성 나노 판의 탄성이론을 재 공식화하기 위하여 에링겐의 비국소 미분 구성 관계식을 사용하였다. 변분이론을 이용하여 비국소 탄성이론의 지배방정식을 연구하였 다. 비국소 이론과 국소 이론의 관계를 계산 결과를 통하여 분석하였다. 또한, 비국소 매개변수, 면내 하중 방향 그리고 형상 비에 따른 구조적 응답을 연구하였다. 계산 결과들은 전위 및 자위의 효과를 나타내었다. 이러한 계산 결과들은 자기-전기-탄성 재료로 구성된 신소재 구조물의 설계 및 해석에 사용될 수 있고 향후 연구의 비교자료가 될 수 있을 것으로 판단된다.

The simplified plate theory is presented for static and free vibration analysis of power-law(P) and sigmoid(S) Functionally Graded Materials(FGM) plates. This theory considers the parabolic distribution of the transverse shear stress, and satisfies the condition that requires the transverse shear stress to be zero on the upper and lower surfaces of the plate, without the shear correction factor. The simplified plate theory uses only four unknown variables and shares strong similarities with classical plate theory(CPT) in many aspects such as stress-resultant expressions, equation of motion and boundary conditions. The material properties of the plate are assumed to vary according to the power-law and sigmoid distributions of the volume fractions of the constituents. The Hamilton’s principle is used to derive the equations of motion and Winkler-Pasternak elastic foundation model is employed. The results of static and dynamic responses for a simply supported FGM plate are calculated and a comparative analysis is carried out. The results of the comparative analysis with the solutions of references show relevant and accurate results for static and free vibration problems of FGM plates. Analytical solutions for the static and free vibration problems are presented so as to reveal the effects of the power law index, elastic foundation parameter, and side-to-thickness ratio.

Measuring the exact cable tension force is important to cable supported bridge under construction and on service. This study was planned to propose EM(electro-magnetic) sensor-based method for measuring the tension force of MS(multi-strand) cable in cable-stayed and extradosed bridge. The tension force in each strand is the same due to MS cable construction using Iso-tensioning system. Therefore, In this prosed method, EM sensor was installed directly at a strand and the measurement model was established for estimating the tension force of strand via EM sensor by experiments. The measurement model was derived from the relation of tension force and magnetic permeability. Also, the magnetic permeability is shown to be different according to the magnetization characteristic of 1860MPa and 2200MPa high-strength strand. The difference is increased as tension force increases. Additional experiment was conducted to verify the measurement model. As a result, the distribution of strand tension calculated upon the EM sensor is similar to those of tension measured by load cell. This proposed approach can be an effective tool for monitoring and measuring the cable force of MS cable.

In this paper, we study the calculation for the damage area of the tension specimens using image processing techniques. This study was able to calculate the area of the damage region on the basis of original image. Generally, to extract the area in the original image, we have to use opening operation, close operation, the Hit-or-Miss operation and bottom hat filter, top hat filter, etc. In particular, to extract the area of the composite specimen discussed in this study, we have to use the combination of the operations and filters because it is non-isotropic material, or should develop a new algorithm based on it.

Bridge construction cost estimates have generally been conducted by using historial unit-price(per meter or square meter). The traditional estimating method based on unit-price references can never completely reflect the specialty of cable supported bridge. In this paper, we have developed the system for supporting the approximate construction cost and the quantity estimation based on 3D model information in the pre-project planning phase of 3-span continuous suspension bridge with 2-pylons. First of all, we’d analyzed the design information (such as structural design report, blueprint and quantity) and the real cost data from the existing suspension bridges and derived the design variables of the bridges. We developed the BIM wizard that generates a suspension bridge model parametrically based on derived design variables. The principle material quantities of suspension bridge are calculated directly from 3-dimensional bridge model built by using the BIM wizard. We have established the system that the construction cost can be estimated more specific than the traditional estimating method.

지수 함수 및 멱 법칙 함수를 이용한 점진기능재료(FGM) 판의 전단 및 두께 방향 변형을 고려한 이론을 정식화하여 동적 평형방정식을 유도하였다. 지수 함수 및 멱 법칙 함수는 두께 방향으로 재료의 변화를 고려할 수 있고 3차원 해석방법은 전단 및 두께 방향 변형을 고려함으로써 점진기능재료의 정확한 구조적 특성을 고려할 수 있다. Pasternak탄성지반 위에 놓인 4변이 단순 지지되고 전단 및 두께 방향 변형이 고려된 점진기능재료 판의 지배방정식을 풀기 위해 Navier 방법을 사용하였다. 거듭제곱 지수와 3차원 해석의 효과를 나타내기 위한 지수 및 멱 법칙 점진기능재료 판의 동적 해석결과를 제시하였다. 기존의 2차원 고차전단변형 이론 및 3차원 이론과의 관계를 수치해석 결과를 통하여 고찰하였다. 또한 (i) 거듭제곱 지수, (ii) 폭-두께 비, 그리고 (iii) 탄성지반 계수, 등이 점진기능재료 판의 자유진동수에 미치는 효과에 대하여 관찰하였다. 본 연구의 결과를 검증하기 위해 참고문헌의 결과들과 비교 분석하였다.

The domestic and foreign specifications presented the effective width based on flange length to width ratio only. The existing paper on the effective width grasped of the effect of span, load type and cross-section properties, but localized steel bridges. Recently, The studies are going on in progress for the application of fiber reinforced composite material in construction field. Therefore, it is required to optimum design that have a good grasp the deformation characteristic of the displacements and stresses distribution and predict variation of the effective width for serviceability loading. This research addresses the effective width of all composite material box girder bridges using the finite element method. The characteristics of the effective width of composite structures may vary according to several causes, e.g., change of fibers, aspect, etc. Parametric studies were conducted to determine the effective width on the stress elastic analysis of all composite materials box bridges, with interesting observations. The various results through numerical analysis will present an important document for construct all composite material bridges.

탄성지반위에 놓인 S형상 점진기능재료 고차전단변형 판의 동적 불안정성에 대하여 연구하였다. 고차전단변형이론은 점진기능재료 판의 두께방향으로의 전단변형률과 전단응력의 곡선변화 효과를 고려할 수 있다. Mathieu-Hill 방정식의 형태로 유도된 지배방정식에서 Bolotin 방법을 이용하여 동적 불안정 영역을 결정하였다. 동적 불안정 영역의 경계는 동적 하중과 여기진동수와의 관계로 나타내었다. 고차전단변형이론과 탄성지반 효과가 S형상 점진기능재료 판의 동적 불안정성에 미치는 효과를 제시하였다. Winkler와 Pasternak탄성지반 매개변수의 관계를 수치해석 결과를 통하여 고찰하였다. 또한 정적 하중계수, 거듭제곱 지수 그리고 폭-두께비 등의 동적 불안정 영역에 대한 영향을 분석하였다. 본 연구의 결과를 검증하기 위해 참고문헌의 결과와 비교 분석하였다. 본 연구에서 제시한 이론적 발전과 수치결과들은 S형상 점진기능재료 구조물의 동적 불안정 해석을 위한 참고자료로 활용될 수 있을 것이다.

In this study, it is presented analysis results of bending problems in the anisotropic cantilever thick plates and the anisotropic laminated cantilever thin plates bending problems. Finite element method in this analysis was used. Both Kirchoff's assumptions and Mindlin assumptions are used as the basic governing equations of bending problems in the anisothotropic laminated plates. The analysis results are compared between the anisotropic laminated cantilever thick plates and the anisotropic laminated cantilever thin plates for the variations of thickness-width ratios.

본 연구에서는 비등방성 적층 캔틸레버 박판 및 후판의 휨문제에 대한 해석결과를 제시하였다. 수치해석방법으로 는 유한요소법을 사용하였으며, 비등방성 적층 캔틸레버 판의 휨문제에 대한 지배방정식은 Kirchhoff 가정에 의 한 박판이론과 Mindlin 가정에 의한 후판이론을 이용하여 유도하였으며 판의 폭-두께비의 변화에 따른 해석결과 를 비교검토하였다.

This paper is presented for the analysis results of the bending problems of the anisotropic cylindrical shells. In the numerical analysis of various mechanical problems involving complex partial differential equations, Finite element method is used to analyze the governing equations of anisotropic cylindrical shells. Both thin shell theory and thick shell theory are used as the basic governing equations of bending problems in the anisotropic cylindrical shells. The analysis results are compared between the anisotropic thick cylindrical shells and the anisotropic thin cylindrical shells. The results of this study will be contribute to analyze the bending behavior of anisotropic cylindrical shells.

In this paper, we used various shear deformation functions for modelling isotropic, symmetric composite and sandwich plates discretized by a mixed finite element method based on the Lagrangian/Hermite interpolation functions. These shear deformation theories uses polynomial, trigonometric, hyperbolic and exponential functions through the thickness direction, allowing for zero transverse shear stresses at the top and bottom surfaces of the plate. All shear deformation functions are compared with other available analytical/3D elasticity solutions, are predicted the reasonable accuracy for investigated problems. Particularly, The present results show that the use of exponential shear deformation theory (Karama et al. 2003; Aydogu 2009) provides very good solutions for composite and sandwich plates.

본 연구는 원형 및 비원형(타원형)단면을 갖는 복합폐합쉘의 좌굴하중 및 모드형상을 비교⋅분석하였다. 이때, 면내 회전자유도를 갖는 평면응력 요소와 추가변형률과 대체전단변형률을 도입한 휨 요소를 결합한 4절점 쉘 요소 (4EAS-FS)를 작성하여 좌굴해석을 수행하였다. 해석모델의 매개변수는 기하학적 형상, 종횡비 및 화이버 보강각도 로 설정하여 그에 따른 영향을 고찰하였다. 본 연구에서 제시한 원형 및 비원형 단면을 갖는 폐합쉘의 임계좌굴하 중과 모드형상에 대한 폐합쉘 길이, 두께, 단면계수 및 화이버 보강각도 등 설계변수의 영향을 비교⋅분석하였다.

최근들어 매스콘크리트 구조물의 시공이 증가 추세에 있다. 이러한 매스콘크리트는 수화열상승으로 온도균열이 발생할 수 있다. 온도균열을 방지하기 위하여 일반적으로 프리 쿨링, 파이프 쿨링 및 타설높이를 제한하는 방법이 사용된다. 본 연구에서는 교각 기초의 온도균열을 방지하기 위하여 열응력 검토를 실시하였으며, 이때 기초는 12m×14m의 면적과 3m 높이를 가지는 것을 모델로 하였다. 타설 높이를 제한하는 방법과 파이프 쿨링에 의한 해석결과를 비교 검토 하였다. 온도응력를 해석한 결과 지반위에 타설한 기초매트는 타설높이를 제한하는 방법과 파이프쿨링 방법에 의해 균열을 제어할 수 있다.