• International Journal of Fluid Machinery and Systems
• /
• 제6권1호
• /
• pp.18-24
• /
• 2013

In order to apply the design method of diagonal flow fan based on axial flow design to the design of radial-outflow type diagonal flow fan which has lower specific speed of 600-700 [$min^{-1}$, $m^3/min$, m], radial-outflow type diagonal flow fan which specific speed was 670 [$min^{-1}$, $m^3/min$, m] was designed by a quasi three-dimensional design method. Experimental investigations were conducted by fan characteristics test, flow surveys by a five-hole probe and a hot wire probe. Fan characteristics test agreed well with the design values. In the flow survey at rotor outlet, the characteristic region was observed. Two flow phenomena are considered as the cause of the characteristic region, one is tip leakage vortex near rotor tip and another is pressure surface separation on the rotor blade.

• 대한기계학회논문집A
• /
• 제29권11호
• /
• pp.1527-1533
• /
• 2005

Three methods for design sensitivity analysis such as finite difference method(FDM), direct differentiation method(DDM) and adjoint variable method(AVM) are well known. FDM and DDM for design sensitivity analysis cost too much when the number of design variables is too large. An AVM is required to compute adjoint variables from the simultaneous linear system equation, the so-called adjoint equation. Because the adjoint equation is independent of the number of design variables, an AVM is efficient for when number of design variables is too large. In this study, AVM has been extended to the eigenproblem of damped systems whose eigenvlaues and eigenvectors are complex numbers. Moreover, this method is implemented into a commercial finite element analysis program by means of the semi-analytical method to show applicability of the developed method into practical structural problems. The proposed_method is compared with FDM and verified its accuracy for analytical and practical cases.

• 전자공학회논문지SC
• /
• 제46권3호
• /
• pp.59-65
• /
• 2009

최근 무인기의 형태는 다양한 형태로 개발되고 있으며, 탑재 장비의 고성능 소형화를 바탕으로 무인기는 소형화되고 있다. 이러한 소형화되고 일반적인 형태가 아닌 무인기 개발에 있어, 기존의 개발방법으로는 이러한 비선형적인 요소로 인하여 정확한 모델링 및 제어기 알고리즘의 정형화하기가 어렵다. 따라서 본 논문에서는 기존이 비행체 개발 방법이 아닌, 하중 제어 개념을 적용한 Min 설계 방법의 첫 번째 단계로, 원통형 무인기에 적용하여, 수평 비행 조건과 특성 그리고 제어기 설계 알고리즘을 찾아보았다. 이러한 Min 설계 방법은 고성능 컴퓨터를 사용한 무인기 개발에 있어 실시간 시뮬레이션을 통한 비용절감과 개발기간을 단축시킬 수 있다.

• 한국산학기술학회논문지
• /
• 제9권6호
• /
• pp.1585-1591
• /
• 2008

현재 움직이는 물체의 운동을 제어하기 위해 하중이라는 개념의 사용이 시도되고 있다. 하중이라는 제어 개념으로 불확실성으로 인한 비선형성을 포함한 시스템에서 신뢰성 있는 제어값을 찾기 위해 MIN 설계 방법이 제안되었다. 이러한 MIN설계 방법에서는 기존의 선형화 방법에 의한 상태방정식에서의 제어값을 찾는 문제와 달리 비선형하중 모델에서 직접 제어 값을 찾는 방식을 보이고 있다. 본 논문에서는 미사일 하중 운동역학과 유도 기하학의 비선형 역학을 고려한 하중 제어값을 찾는다. 즉 시선각 또는 미사일의 받음각 변화에 따른 진행방향에 대한 미사일의 속도 조건을 만족하기 위한 제어값과 표적을 따라가기 위한 선회 각도을 위한 제어값을 구한다. 즉 본 논문에서는 미사일 시스템과 추적 동역학에서 하중 제어값을 구해본다. 이렇게 구해진 하중 제어값으로 유도 제어 법칙을 비선형 시스템에서 직접 쉽게 구할 수 있음을 확인해 보았다.

• 소성∙가공
• /
• 제17권4호
• /
• pp.257-262
• /
• 2008

The control of wire temperature is very important in the fine wire drawing process. The wire speed should be increased, and the wire temperature should be dropped as much as possible. Up to now, the process design of wire drawing process depends on the experiences of experts. In this study, a wire drawing process design method was proposed to increase the productivity. The proposed method of this study includes the pass schedule and the design of a multi pass wire drawing machine. A pass schedule was performed based on the calculation of the wire temperature. Also, a new multi pass wire drawing machine was manufactured to apply the designed pass schedule. Through the wire drawing experiment, the effectiveness of the proposed process design method was evaluated. The final drawing speed was increased from 1,100m/min to 2,000m/min without deterioration of final drawn wire.

• 한국실내디자인학회:학술대회논문집
• /
• 한국실내디자인학회 2004년도 추계학술발표대회 논문집
• /
• pp.181-184
• /
• 2004

The Presentation show the Interior Design for Environmental Early Age, with Motive Montessori Method that 'Environmetal Prepared'. there is Concentral System in Architecture from PEDAGOGIA. in the Class, students can application for ' Casa dei Bambini' through historical architecture from nothen Italy and the matter needs consideration about Planning interior for Environmetal Childhood. as presented on Pannel with Graphic, there are four major motives of Design Process ; Activities classwork, understanding Method Montessori, Design exterior from Concentral System and the Interior Design.

• Structural Engineering and Mechanics
• /
• 제5권5호
• /
• pp.565-576
• /
• 1997

The material-based homogenization design method generates arbitrary topologies of initial structural design as well as reinforcement structural design by controlling the amount of material available. However, if a small volume constraint is specified in the design of Lightweight structures, thin and slender structures are usually obtained. For these structures stability becomes one of the most important requirements. Thus, to prevent overall buckling (that is, to increase stability), the objective of the design is to maximize the buckling load of a structure. In this paper, the buckling analysis is restricted to the linear buckling behavior of a structure. The global stability requirement is defined as a stiffness constraint, and determined by solving the eigenvalue problem. The optimality conditions to update the design variables are derived based on the sequential convex approximation method and the dual method. Illustrated examples are presented to validate the feasibility of this method in the design of structures.

• Natural Product Sciences
• /
• 제27권4호
• /
• pp.264-273
• /
• 2021

Simultaneous quantification of multiple marker compounds in herbal medicine by high performance liquid chromatography (HPLC) analysis is still a challenge due to the complexity in various parameters to be considered and co-existing multi-components. As a case study, a reliable HPLC method for simultaneous quantification of paeoniflorin from Paeoniae Radix and decursin from Angelicae Gigantis Radix in various commercial herbal medicine was developed based on analytical quality by design (AQbD) strategy. As a first step, risk assessment was performed to select the critical method parameters (CMPs) which were decided as organic mobile phase ratio and column oven temperature. In order to evaluate the effect of the CMPs on critical method attributes (CMAs) of peak resolution and tailing, central composite design (CCD) was employed. The final chromatographic conditions were optimized as follows: column- C₁₈, 4.6 × 250 mm, 5 ㎛ particle size; mobile phase- A: acetonitrile, B: 0.1% acetic acid water; detection wavelength- 235 nm for paeoniflorin, 325 nm for decursin; column oven temperature- 25℃; flow rate- 1.0 mL/min; gradient mobile phase system as Time (min) : % A, 0:14, 25:14, 30:50, 60:50, 61:100, 65:100, 66:14, 75:14. The method was successfully validated according to the International Conference on Harmonization (ICH) guidelines and piloted for ten commercial herbal medicines.

• 한국산학기술학회논문지
• /
• 제13권5호
• /
• pp.2030-2037
• /
• 2012

본 연구의 목적은 공업 기술 영어 교과의 교수요목을 설계하기 위한 요구분석의 한 모형을 제안하는 데 있다. 이는 학습자 중심의 교육이 보편화됨에 따라 학습자들의 요구를 학습 내용에 효율적으로 반영하기 위한 방법론을 모색하고자 하는 것이다. 기존의 표준화 점수에 의해 교수요목 순위 선정을 하는 연구에서는 최댓값과 최솟값의 차이가 설문지에서의 Likert 5점 척도보다 크기 때문에 자료를 해석할 때 왜곡될 수 있는 단점을 갖고 있으므로 이에 대한 보완책이 필요하다. 이러한 자료해석의 왜곡을 최소화 해줄 수 있는 방법이 Max-Min 방법이다. 이 논문에서는 기존의 표준화 점수 방법을 이용한 교수요목 선정과 Max-Min 점수 방법에 의한 교수요목 선정의 차이를 밝히고 그 의의를 제시해 본다. 순위 변화율은 기계 금속 관련 항목, 토목 건축 관련, 화공 섬유 관련이 각각 25%, 25%, 55%의 변화율을 보였다. 요구분석은 상황에 맞게 다양하게 선택되어야 하며, 또한 요구분석이 언어 교수요목 설계의 출발점이라고 할 때 이에 대한 정교한 방법론이 필요하다. 따라서 앞으로의 요구분석과 관련한 연구에서는 표준화 방법이나 Max-Min 방법 문제뿐만 아니라 심층연구를 통해서 각 집단의 중요도 차이를 반영할 수 있는 방법론에 대해서도 다각도의 연구가 진행되어 궁극적으로는 요구분석 전반을 아우를 수 있는 방법론 개발이 필요하다.

• 한국전산구조공학회논문집
• /
• 제23권6호
• /
• pp.683-691
• /
• 2010

In this paper, using an adjoint variable method, we develop a design sensitivity analysis(DSA) method applicable to heat conduction problems in steady state. Also, a topology design optimization method is developed using the developed DSA method. Design sensitivity expressions with respect to the thermal conductivity are derived. Since the already factorized system matrix is utilized to obtain the adjoint solution, the cost for the sensitivity computation is trivial. For the topology design optimization, the design variables are parameterized into normalized bulk material densities. The objective function and constraint are the thermal compliance of structures and allowable material volume respectively. Through several numerical examples, the developed DSA method is verified to yield very accurate sensitivity results compared with finite difference ones, requiring less than 0.25% of CPU time for the finite differencing. Also, the topology optimization yields physical meaningful results.