• 소성∙가공
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• 제11권7호
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• pp.608-613
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• 2002

An ultrasonic machining process is efficient and economical means for precision machining of glass and ceramic materials. However, the mechanism of the process with respect to the crack initiation and propagation and the stress development in the ceramic workpiece subsurface arc still not well understood. In this research, we have investigated the basic mechanism of ultrasonic machining of ultrasonic machining of glass by the experimental approach. For this purpose, we designed and fabricated the desktop micro ultrasonic machine. The feed is controlled precisely by using the constant load control system. During machining experiments, the effects of abrasive characteristics and machining conditions on the surface roughness and the material removal rate are measured and compared.

• 한국공작기계학회논문집
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• 제10권5호
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• pp.39-44
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• 2001

In this paper, drill fred mechanism, cutting depth measuring device and sensing buzzer of drill contact were investigated in order to develop the micro-hole drilling machine. Also, measuring device of cutting resistance was developed in order to estimate cutting resistance from change of cutting condition. The results show that extremely-low fled rate(less then $17{\mu}m/S$${\mu}{\textrm}{m}$ /s) can be done and cutting depth can be measured by up to 1${\mu}{\textrm}{m}$ with developed drilling machine. Accordingly we could assemble a very cheap micro-hole drilling machine($\phi$ 0.05~0.5 mm). Also we got the some properties of cutting performance i.e. under the same condition, cutting torque decreases as increase of spindle speed and rapid fled of drill brings about the inferior cutting state under low spindle speed.

• 한국정밀공학회지
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• 제25권6호
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• pp.126-133
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• 2008

Linear motors are efficient mechanism that offers high speed and positioning accuracy. By eliminating mechanical transmission mechanisms such as ball screw or rack-pinion, much higher speed and greater acceleration can be achieved without backlash or excessive friction. However, an important disadvantage of linear motor system is its high power loss and heating up of motor and neighboring machine components on operation. For the application of the linear motors to precision machine tools an effective cooling method and thermal optimizing measures are required. This paper presents an investigation into the thermal behavior of linear motors with the objective of deriving the optimum cooling conditions. To reach these goals several experiments were carried out, varying operating and cooling conditions. From the experimental results, this research proposed cooling conditions to improve the thermal characteristics of the linear motors.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계학술대회논문집
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• pp.569-572
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• 2005

In many machines handling lightweight and flexible media, such as automated teller machines(ATM) and printers etc., the media must transit an open space. In the paper feeding mechanism, it is important to feed the sheet without jamming under any conditions. To avoid sheet jamming, first we need to predict the behavior of the sheet exactly. The nonlinear theory of the dynamic elastica has often been used to a nonlinear dynamic deflection model. In this paper, the governing equation is derived and simulated by the finite difference method. The analysis has to include aerodynamic effect for more exact behavior analysis. For verification of the numerical simulation, the experiments were performed using high-speed camera and feeding mechanism. The experimental results show good agreement with the numerical simulations.

• Corrosion Science and Technology
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• 제20권5호
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• pp.242-248
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• 2021

Unforeseen failures of boilers in power plants may affect the continuation of electricity generation. Main failures in boilers are influenced by the tube material, tube position, boiler service temperature and pressure, and chemical composition of the feed water and coal. This investigation was intended to find answers on the causes and mechanism of failure of the fire-side boiler water-wall tubes, due to perforation and corrosion. The tube conformed to the material requirements in terms of its chemical composition and hardness. Microscopic examination showed ferrite and pearlite indicating no changes in its microstructure due to the temperature variation. SEM test showed a single layer and homogenous film density particularly on the area far from perforation. However, layers of corrosion product were formed on the nearby perforation area. EDX showed that there were Na, Ca, S, and O elements on the failed surface. XRD indicated the presence of Fe₂O₃ oxide. The failure mechanism was identified as a result of significant localized wall thinning of the boiler water wall-tube due to oxidation.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.1525-1529
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• 2004

Most of the recently developed robots are human friendly robots which imitate an animal or human such as entertainment robot, bio-mimetic robot and humanoid robot. Interest in these robots are increasing since the social trend is focused on health, welfare, and graying. By these social backgrounds, robots become more human friendly and suitable for home or personal environment. The more bio-mimetic robots resemble living creature, the more human feels familiarity. People feel close friendship not only when they feed a pet, but also when they watch a pet having the food. Most of entertainment robots and pet robots use internal-type batteries and have a self-recharging function. Entertainment robots and pet robots with internal-type batteries are not able to operate during charging the battery. So far there have been a few robots that do not depend on a battery. However, they need a bulky energy conversion unit and a slug or foods as an energy source, which is not suitable for home or personal application. In this paper, we introduce a new bio-mimetic entertainment robot with autonomous feeding functionality, called ELIRO-1(Eating LIzard RObot version 1). The ELIRO-1 is able to find a food (a small battery), feed by itself and evacuate. We describe the design concept of the autonomous feeding mechanism of the ELIRO-1, characteristics of sub-parts of the manufactured mechanism and the control system.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 춘계 학술발표회 제20권1호
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• pp.957-960
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• 2008

최근 급격히 진행되고 있는 도심지 구조물의 대형화, 고층화에 따른 고층건물의 해체뿐 아니라 극한 환경의 해체현장에서 기존의 해체공법은 인력+장비에 의한 해체작업을 수행하여 언제나 작업자에 대한 치명적인 위험에 노출되어 있었다. 따라서 본 연구는 낙후된 해체산업을 첨단화시키고, 안전하고 친환경적인 해체장비 및 공법을 개발하고자 한다. 이를 위해 첫 번째, 선진외국의 해체장비인 B사(社)와 국내 무인해체장비인 M사(社)의 장비 성능을 비교분석하기 위한 장비시연회를 개최하였다. 이러한 성능의 비교분석을 토대로 해체산업에서 요구되는 기능을 도출하고, 그에 적합한 햅틱장치(haptic device) 기술, 힘반향 메카니즘(force feed-back mechanism), 환경인식용 센서퓨전(sensor fusion) 기술등 첨단기능이 융합된 무인해체 장비의 요소기술을 제안하였다. 이를 토대로 먼저, 새로운 햅틱장치 (haptic device)를 고안하였다. 두 번째로 기존의 고층건물의 기계식 해체공법을 개선한 탑다운 (Top-Down) 해체장치 및 공법을 제시하였다.

• 한국산학기술학회논문지
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• 제8권5호
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• pp.961-967
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• 2007

양계 농장의 자동화 시설 중 닭에 물을 공급하는 자동 급수 장치는 닭 사육을 위한 가장 중요한 시설중의 하나이다. 이 장치 부품 중 급수 니플은 닭이 직접 물을 먹는 장치이며 그 내부에 체크 밸브가 있어 물 공급 시에는 열리고 물을 먹지 않을 경우는 닫히게 된다. 니플의 종류는 피스톤 니플과 볼 니플로 나누워지며 볼 니플은 니플 스틱의 운동이 자유롭게 되어 낙수의 차단이 잘되는 장점이 있으나 복잡한 구조를 갔고 있는 단점이 있다. 이에 반하여 피스톤 니플은 구조가 간단한 장점이 있는 반면에 대부분 상하운동만 가능한 단점이 있다 최근에 이를 보완하기 위하여 피스톤 니플에 밸브 시트면을 구 형태로 제작하여 피스톤 형식이면서 자유로운 운동이 가능 하도록 한 구조(이하 : 구면 피스톤 니플)가 개발 되었다. 본 실험에서는 최근 관심을 갖게된 구면 피스톤 니플에 대한 성능 평가를 수행하였으며 그 결과를 국내외 기존 제품인 볼 니플 및 피스톤 니플과 성능을 실험적으로 비교 분석하였다. 그 결과 구면 피스톤 니플의 성능은 기존 피스톤 니플 보다는 좋은 결과를 얻었으며 볼 니플과는 유사한 성능임을 확인하였다.

• Smart Structures and Systems
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• 제18권6호
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• pp.1233-1250
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• 2016

Cracks in plate-like structures are some of the main reasons for destruction of the entire structure. In this study, a novel two-stage methodology is proposed for damage detection of flexural plates using an optimized artificial neural network. In the first stage, location of damages in plates is investigated using curvature-moment and curvature-moment derivative concepts. After detecting the damaged areas, the equations for damage severity detection are solved via Bat Algorithm (BA). In the second stage, in order to efficiently reduce the computational cost of model updating during the optimization process of damage severity detection, multiple damage location assurance criterion index based on the frequency change vector of structures are evaluated using properly trained cascade feed-forward neural network (CFNN) as a surrogate model. In order to achieve the most generalized neural network as a surrogate model, its structure is optimized using binary version of BA. To validate this proposed solution method, two examples are presented. The results indicate that after determining the damage location based on curvature-moment derivative concept, the proposed solution method for damage severity detection leads to significant reduction of computational time compared with direct finite element method. Furthermore, integrating BA with the efficient approximation mechanism of finite element model, maintains the acceptable accuracy of damage severity detection.

• 한국안전학회지
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• 제27권5호
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• pp.77-87
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• 2012

Compared to a batch reactor, where all reactants are initially charged to the reactor, the semi-batch reactor presents serious advantages. The feed of at least one of the reactants provides an additional way of controlling the reaction course, which represents a safety factor and increases the constancy of the product quality. The aim of this study was to investigate the characteristics of thermal hazard such as a feed time, catalysis concentration and solvent concentration in methylthioisocyanate(MTI) synthesis reaction process. The experiments were carried out by the Multimax reactor system and Accelerating rate calorimeter(ARC). The MTI synthesis reaction process has many reaction factors and complicated reaction mechanism of multiphase reaction. Through this study, we can use as a tool for assessment of thermal hazard of other reaction processes by applying experiment method provided.