• Journal of Welding and Joining
• /
• 제34권3호
• /
• pp.69-76
• /
• 2016

Characteristics of dissimilar metal welds between ASTM Type 316L and carbon steel ASTM A516 Gr.70 made with FCAW were evaluated in terms of microstructure, ferrite content, EDS analysis, hardness, tensile strength, impact toughness and corrosion resistance. Three heat inputs of 10.4, 16.9, 23.4kJ/cm were employed to make joints of dissimilar metals with E309LMoT1-1 wire. Microstructure of dissimilar weld metals consisted of mostly vermicular type of ${\delta}$-ferrite and some lathy type of ${\delta}$-ferrite, and ${\delta}$-ferrite was transformed into globular type in reheated zone. In all conditions, weld metals were solidified on FA solidification mode. Based on the EDS analysis of weld metals, All Creq/Nieq values were in the range of FA solidification mode, and it was decreased with increasing heat inputs whereas it was increased with increasing layers. The amount of ${\delta}$-ferrite was decreased with increasing heat input due to the difference of cooling rate, and it was increased with increasing layers. Accordingly, hardness and tensile strength of dissimilar metals weld joints was decreased with increasing heat input while impact energy was increased with increasing heat input. Corrosion test of dissimilar metals weld joints showed that weight gain rate of heat input 10.4kJ/cm was the greatest, and that of three heat inputs became constant after certain time.

• 디지털콘텐츠학회 논문지
• /
• 제6권4호
• /
• pp.235-242
• /
• 2005

본 연구는 대학에서 사이버교육에 영향을 미치는 요인을 분석하고자 실시되었다. 먼저 사이버교육의 개념과 그 특성을 고찰하고 사이버교육의 평가준거들에 대한 선행연구들을 분석하여 본 연구에 적합한 교육효과 관련 변인들을 선정하였다. 연구 모형은 체제론에 입각한 투입-과정-산출 모형을 적용하여 투입변인은 교수, 학생, 학습 환경이고, 과정변인은 교육내용, 상호작용, 강의참여이며, 산출변인은 교육효과성과 교육만족도로 하였다. 분석은 투입-과정-산출과정에서 관련 변인들이 어떤 관계가 있으며, 실제 사이버교육에서 어느 정도 영향을 미치는지를 분석하였다. 이를 분석하기 위해서 사이버강의에 참여하고 있는 190명의 학생들을 대상으로 실증적인 연구를 하였다. 주요 연구결과에 따른 결론을 보면 다음과 같다. 첫째 학생들이 사이버교육에 참여한 시간이 많거나 성적이 높을수록 사이버교육 효과에도 긍정적으로 인식한다. 둘째, 사이버교육이 잘 이루어지기 위해서는 처음에는 교수의 역할이 중요하다. 셋째, 사이버교육의 효과를 높이기 위해서는 사이버교육의 교육내용과 학생들의 강의참여가 중요하다.

• 반도체디스플레이기술학회지
• /
• 제16권2호
• /
• pp.98-105
• /
• 2017

In the display industry, the residual vibration of the transfer robot can increase the process time and cause the breakage of the glass substrate, which is critical to productivity of display manufacturing. In this paper, the natural frequencies of transfer robot are analyzed by finite element method. On the basis of the analyzed data, we investigated the response characteristics of input shaping control with or without the glass presence on the hand of the transfer robot using MATLAB program, and compared with the current response characteristics of input shaping control applied to the industry. Based on this, we suggest an optimal residual vibration control method for the practical application in display industry.

• Journal of Power Electronics
• /
• 제17권1호
• /
• pp.200-211
• /
• 2017

Conventional boost-full-bridge and boost-hybrid-bridge two-stage inverters are widely applied in order to adapt to the wide dc input voltage range of photovoltaic arrays. However, the efficiency of the conventional topology is not fully optimized because additional switching losses are generated in the voltage conversion so that the input voltage rises and then falls. Moreover, the electrolytic capacitors in a dc-link lead to a larger volume combined with increases in both weight and cost. This paper proposes a higher efficiency inverter with time-sharing synchronous modulation. The energy transmission paths, wheeling branches and switching losses for the high-frequency switches are optimized so that the overall efficiency is greatly improved. In this paper, a contrastive analysis of the component losses for the conventional and proposed inverter topologies is carried out in MATLAB. Finally, the high-efficiency under different switching frequencies and different input voltages is verified by a 3 kW prototype.

• 한국전기전자재료학회논문지
• /
• 제32권1호
• /
• pp.13-19
• /
• 2019

This paper proposes an easy algorithm for finding tapped-delay-line (TDL) filter coefficients in an adaptive filter algorithm using orthogonal input signals. The proposed algorithm can be used to obtain the coefficients and errors of a TDL filter without using an inverse orthogonalization process for the orthogonal input signals. The form of the proposed algorithm in this paper has the advantages of being easy to use and similar to the familiar recursive least-squares (RLS) algorithm. In order to evaluate the proposed algorithm, system identification simulation of the $11^{th}$-order finite-impulse-response (FIR) filter was performed. It is shown that the convergence characteristics of the learning curve and the tracking ability of the coefficient vectors are similar to those of the conventional RLS analysis. Also, the derived equations and computer simulation results ensure that the proposed algorithm can be used in a similar manner to the Levinson-Durbin algorithm.

• 한국디지털건축인테리어학회논문집
• /
• 제12권1호
• /
• pp.25-33
• /
• 2012

Ever since the local interior and architecture design industry adopted Digital fabrication modeling tool for its design operation in early 1990's, working environment has been changing. The Purpose of study is to analyze the digital Architecture fabrication modeling for digital design education in academy course. Digital Design Tools, Digital Space and Form, Digital Materiality and Digital Production. The Digital fabrication modeling is and important role in a traditional design process and digital design process. It is comprised of digital input devices(3D digitizer, 3D design tools) and digital output devices(cutting plotters, laser cut, CNC machines, 3D printers). Digital input devices can be shift a traditional design process to digital design process. Digital output devices are the principle of digital fabrication by CAD/CAM. Also, the result of this study provide the fundamental data for physical resources and digital design curriculum in KAAB.

• 한국항행학회논문지
• /
• 제19권5호
• /
• pp.452-457
• /
• 2015

최근 사용자들의 취향을 고려하는 다양한 디자인을 내세워 기존의 안경, 시계 등의 친숙한 형태의 웨어러블 디바이스가 등장하면서 많은 인기를 얻고 있다. 하지만 착용이 가능한 초소형 디바이스라는 특성을 고려하지 않고 기존의 스마트폰 UI/UX를 적용하였기 때문에 작은 디스플레이 상에서 문자 입력이라는 문제점을 안고 있다. 이에 본 논문에서는 스마트워치와 같은 웨어러블 디바이스의 기존 입력 방법과 관련 연구들을 분석하여 UI/UX에 대한 문제점을 도출하고 스마트 워치를 위한 새로운 입력 방식을 제안한다. 이를 위해, 트랙볼 센서를 활용하여 웨어러블 디바이스에서 효율적인 문자 입력이 가능하도록 설계하고 구현한 결과를 통해 제안된 인터페이스의 유용성 및 성능을 검증한다.

• Smart Structures and Systems
• /
• 제31권2호
• /
• pp.131-140
• /
• 2023

As well-known, the extended Kalman filter (EKF) is a powerful tool for parameter identification with limited measurements. However, traditional EKF is not applicable when the external excitation is unknown. By using least-squares estimation (LSE) for force identification, an EKF with unknown input (EKF-UI) approach was recently proposed by the authors. In this approach, to ensure the influence matrix be of full column rank, the sensors have to be deployed at all the degrees-of-freedom (DOFs) corresponding to the unknown excitation, saying collocated measurements are required. However, it is not easy to guarantee that the sensors can be installed at all these locations. To circumvent this limitation, based on the idea of first-order-holder discretization (FOHD), an improved EKF with unknown input (IEKF-UI) approach is proposed in this study for the simultaneous identification of structural parameters and unknown excitation. By using projection matrix, an improved observation equation is obtained. Few displacement measurements are fused into the observation equation to avoid the so-called low-frequency drift. To avoid the ill-conditioning problem for force identification without collocated measurements, the idea of FOHD is employed. The recursive solution of the structural states and unknown loads is then analytically derived. The effectiveness of the proposed approach is validated via several numerical examples. Results show that the proposed approach is capable of satisfactorily identifying the parameters of linear and nonlinear structures and the unknown excitation applied to them.

• 한국지능시스템학회:학술대회논문집
• /
• 한국퍼지및지능시스템학회 2006년도 춘계학술대회 학술발표 논문집 제16권 제1호
• /
• pp.302-305
• /
• 2006

A problem that arises in most communication receivers concerns the wide variation in power level of the signals received at the antenna. These variations cause serious problems which can usually be solved in receiver design by using Automatic Gain Control (AGC). AGC is achieved by using an amplifier whose gain can be controlled by external current or voltage. However, the AGC circuit does not respond to rapid changes in the amplitude of input. If input changes instantaneously, then even if op-amps could follow the change, the envelope detector capacitor could not, since the capacitor's voltage could not change instantaneously. To alleviate this deficiency, we present Improved Automatic Gain Control Circuit (IAGCC) replacing AGC circuit to FLC.

• 산업경영시스템학회지
• /
• 제29권1호
• /
• pp.9-17
• /
• 2006

This paper considers a six sigma project for improving productivity of the brace complement center pillar. The project follows a disciplined process of fife phases: define, measure, analyze, improve, and control. A process map is used to identify process input and output variables. Eleven key process input variables are selected by using X&Y matrix and FMEA, and finally eight vital few input variables are selected from analyze phase. The optimum process conditions of the vital few input variables are jointly obtained by maximizing productivity of the brace complement center pillar using DOE and alternative selection method.