• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.723-726
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• 2002

In the recent years, as the research and the development of micro and precision machinery become active, the interest of micro actuators using SMA(Shape Memory Alloy) has been increased. The dynamic characteristic analysis of SMA is necessary for actuator application and many common researches report the material characteristics of SMA sufficiently. However, the research of dynamic characteristics is very deficient. In this paper, the helical spring is fabricated with NiTi SMA wire of high resistivity The farce, response speed, temperature, and displacement are measured by digital force gauge, infrared thermometer, and laser displacement sensor so that the dynamic characteristics of this SMA actuator is analyzed.

• Journal of Biosystems Engineering
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• 제26권3호
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• pp.221-228
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• 2001

Chemical application, one of the most important crop management processes happened to cause spray drift, that would threaten farmers in field as well as dwellers in rural region. Spray drift was affected by micro-meteorological parameters. A study to evaluate short distance drift characteristics of a boom sprayer in paddy fields has been undergoing. This study is the first step of the research. Main purpose of the was conducted to develop a mean wind profile and to get information on turbulence intensities above and within rice canopy. Wind in rice paddy field were measured at every 10cm from 10 to 180cm above the ground using a 2-dimensional probe and a hot wire anemometer system. Main results were summarized as follows. 1. Mean wind profile was modeled as; Equations. see full-text 2. Roughness length and zero-displacement in rice canopy were analyzed to be respectively 0.04 and 0.7∼0.72 times of the canopy height. The values are smaller comparing to those of other crops because rice canopy is flexible and uniform comparing to other crops. 3. Turbulence intensities (Tl) was greater as close to the ground and became constant at heights greater than 1.5Hc. where Tl’s were 0.4 and 0.15 in horizontal and vertical direction respectively.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.1577-1580
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• 2003

In the recent years, as the research and the development of micro and precision machinery become active, the interest of micro actuators using SMA(Shape Memory Alloy) has been increased. The dynamic characteristic analysis of SMA is necessary for actuator application and many common researches report the material characteristics of SMA sufficiently. However, the research on dynamic characteristics is very deficient. In this paper, the helical spring are fabricated with NiTi SMA wire of high resistivity. The force, response speed, temperature, and displacement are measured by digital force gauge, infrared thermometer, and laser displacement sensor so that the dynamic characteristics of this SMA is analyzed. Also, bidirectional actuator was fabricated and experimented for its performance.

• 한국정밀공학회지
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• 제32권3호
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• pp.307-314
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• 2015

In this paper, the embedding type novel liquid metal strain gauge was developed for measuring the deformation of wind turbine blades. In general, the conventional methods for the SHM have many disadvantages such as frequency distortion in FBG sensors, the low gauge factor and mechanical failures in strain gauges and extremely sophisticated filtering in AE sensors. However, the liquid metal filled in a pre-confined micro channel shows dramatic characteristics such as high sensitivity, flexibility and robustnes! s to environment. To adopt such a high feasibility of the liquid metal in flexible sensor applications, the EGaIn was introduced to make flexible liquid metal strain gauges for the SHM. A micro channeled flexible film fabricated by the several MEMS processes and the PDMS replication was filled with EGaIn and wire-connected. Lots of experiments were conducted to investigate the performance of the developed strain gauges and verify the feasibility to the actual wind turbine blades health monitoring.

• 센서학회지
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• 제32권4호
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• pp.232-237
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• 2023

This paper presents a system for estimating the position of a magnet using a magnetic sensor. An algorithm is presented to analyze the waveform and output voltage values of the magnetic field generated at each position when the magnet moves and to estimate the position of the magnet based on the analyzed data. Here, the magnet is sufficiently small to be inserted into a blood vessel and has a micro-magnetic field of hundreds of nanoteslas owing to the small size and shape of the guide wire. In this study, a highly sensitive magneto-impedance (MI) sensor was used to detect these micro-magnetic fields. Nine MI sensors were arranged in a 3×3 configuration to detect a magnetic field that changes according to the position of the magnet through the MI sensor, and the voltage value output was polynomially regressed to specify a position value for each voltage value. The accuracy was confirmed by comparing the actual position value with the estimated position value by expanding it from a 1D straight line to a 3D space. Additionally, we could estimate the position of the magnet within a 3% error.

• 대한화학회지
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• 제11권3호
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• pp.81-84
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• 1967

수은 표면을 바꾸기 쉽고, 사용하기에 편리한 회전수은전극을 고안하였다. 이 전극은 갈아 맞춘 두 유리 부분으로 되어 있다. 그 중 숫 부분의 끝은 백금선 토막을 녹여 넣은 평평한 면으로 막혀있고, 그 옆에 작은 구멍이 하나 뚫여 있다. 암 부분에는 흠이 파여 있고, 모세관(약 1mm 지름)이 붙어있다. 이 구멍과 흠이 마주치면 두 유리 부분의 수은이 오고갈 수 있고, 사용할 때에는 이 연결을 끊어 수은이 흐르지 못하게 한다. 그러나 백금선 토막이 두 부분을 전기적으로 연결한다. 모세관의 끝은 위를 향하게 굽혀 두어, 노출된 수은 부분이 수용액에 바꿔치지 못하게 한다. 이 노출 수은 표면이 미크로전극으로 작용한다. 이 전극은 센산성용액에서의 전류법 적정에 매우 유용하며, 전기저항이 작은 미크로수은전극이기 때문에 교류 플라로그라피에도 유리하다. 또 정류전극으로서도 매우 편리하다.

• 로봇학회논문지
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• 제3권3호
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• pp.203-211
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• 2008

This work proposes structure of spring backbone micro endoscope. For effective surgery in narrow and limited space, many manipulators are developing that different to existed structure. This device can move like elephant nose or snake unlike the existing robots. For this motion, a mechanism that uses spring backbone and wires has been developed. The new type endoscope that has Z axis motion for spring structure, therefore it has 3 degree of freedom, two rotations and one linear motion. And new kinematics for backbone structure is proposed using simple geographic analysis. The Jacobian and stiffness modeling are also derived. Exact actuator sizing is determined using stiffness model. Finally, the proposed kinematics are verified by simulation and experiments.

• 설비공학논문집
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• 제1권4호
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• pp.265-275
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• 1989

An experimental study of decaying swirl air flow has been obtained by tangential inlet in a straight tube with Reynolds number range 20,000~40,000. The friction factor, swirl angle, velocity profiles and turbulent intensity are measured by using micro-manometer and hot-wire anemometer. It is found that the swirl flow behaviors depend on the swirl intensity along the test tube.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.527-531
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• 2007

The classical continuum theory-based thin film model is independent of their size and the surface effect can be ignored. But the surface to bulk ratio becomes very large in nano-size structures such as nano film, nano wire and nano beam. In this case, surface effect plays an important role and its contribution of the surface effect must be considered. Molecular dynamics simulation has been a conventional way to analyze these ultra-thin structures but structures in the range between submicro and micro are difficult to analyze by classical molecular dynamics due to the restriction of computing resources and time. Therefore, in present study, the continuum-based method is considered to predict the overall physical and mechanical properties of the structures in nano-scale, especially, for the thin-film. The proposed continuum based-thin plate finite element is efficient and reliable for the prediction of nano-scale film behavior.

• Journal of Applied Biological Chemistry
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• 제58권2호
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• pp.113-116
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• 2015

Silver materials may be toxic in humans because they can enter the body and accumulate, typically in the lungs. We hypothesized that the cytotoxicity of naive silver materials is affected by their size and shape. Our in vitro assays revealed that the overall toxicity was in the following order: submicro-particles>wires>micro-particles. These results contrast with previous studies, which showed that silver wires are the most toxic among the three tested materials, possibly due to differences in cell lines. Evaluations of in vivo pulmonary toxicity revealed eryptosis in the cavity lining of the lung sections. The observed eryptosis was consistent with the in vitro results. Our results indicate that silver materialinduced cytotoxicity must be measured and compared using various methods.