• International Journal of Fuzzy Logic and Intelligent Systems
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• 제5권4호
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• pp.316-321
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• 2005

We designed and implemented fish robots for various purposes such as autonomous navigation, maneuverability control, posture balancing and improvement of quick turns in a tank of 120 X 120 X 180cm size. Typically, fish robots have 30-50 X 15-25 X 10-20cm dimensions; length, width and height, respectively. It is essential to have the ability of quick and smooth turning to avoid collision with obstacles or walls of the water pool at a close distance. Infrared distance sensors are used to detect obstacles, magneto-resistive sensors are used to read direction information, and a two-axis accelerometer is mounted to compensate output of direction sensors. Because of the swing action of its head due to the tail fin movement, the outputs of an infrared distance sensor contain a huge amount of noise around true distances. With the information from accelerometers and e-compass, much improved distance data can be obtained by fuzzy logic based estimation. Successful swimming and smooth turns without collision demonstrated the effectiveness of the distance estimation.

• 한국정보통신학회논문지
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• 제11권10호
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• pp.1986-1991
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• 2007

본 논문에서 지구자기장을 측정하여 방위를 결정하는 자기 저항 소자의 경사각의 이상 현상에서 있어 예측할 수 없는 특성에 대해 불확실성에서의 추론을 통해 센서로서의 안정성을 확보하는데 그 목적이 있다. 따라서 퍼지 알고리즘을 적용하여 외부 환경 변화에 민감하게 변화하는 소자의 왜곡현상을 프로그래밍 적인 요소를 실험하여 센서의 왜율적인 요소에서 벗어남을 보인다. 나아가 소자의 고속, 고신뢰성을 갖는 응용에 사용할 수 있음을 보인다.

• 센서학회지
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• 제32권1호
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• pp.39-43
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• 2023

Microscale thermophysical property measurements of liquids have been developed considering the increasing interest in the thermal management of cooling systems and energy storage/transportation systems. To accurately predict the heat transfer performance, information on the thermal conductivity, heat capacity, and density is required. However, a simultaneous analysis of the thermophysical properties of small-volume liquids has rarely been considered. Recently, we proposed a new methodology to simultaneously analyze the aforementioned three intrinsic properties using heater-integrated fluidic resonators (HFRs) in an atmospheric pressure environment comprising a microchannel, resistive heater/thermometer, and mechanical resonator. Typically, the thermal conductivity and volumetric heat capacity are measured based on a temperature response resulting from heating using a resistive thermometer, and the specific heat capacity can be obtained from the volumetric heat capacity by using a resonance densitometer. In this study, we analyze methods to improve the thermophysical property measurement performance using HFRs, focusing on the effect of the ambience around the sensor. The analytical method is validated using a numerical analysis, whose results agree well with preliminary experimental results. In a vacuum environment, the thermal conductivity measurement performance is enhanced, except for the thermal conductivity range of most gases, and the sensitivity of the specific heat capacity measurement is enhanced owing to an increase in the time constant.

• 폴리머
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• 제31권4호
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• pp.302-307
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• 2007

저항형 습도센서를 제조하기 위하여 [2-[(methacryloyloxy)ethyl]dimethyl] propylammonium bromide(MEPAB), [2-[(methacryloyloxy)ethyl]-2-hydroxyethyl]dimethylammonium bromide(MEHDAB), 2-[(methacryloyloxy)ethyl]trimethylammonium chloride(METAC), 그리고 n-butyl methylacrylate(BMA)의 공중합체를 사용하였다. 4가지 종류의 4원 공중합체 MEPAB/BMA/MEHDAB/METAC=4/4/1/1, 3/5/1/1, 2/6/1/1, 1/7/1/1을 blocked-isocyanate가교제를 사용하여 Ag/Pd 전극/알루미나에 도포한 후 좋은 내수성을 보여주었다. 습도센서의 상대습도에 대한 주파수 의존성, 온도 의존성, 히스테리시스, 응답속도 그리고 내수성을 평가하였다. MEPAB/BMA/MEHDAB/METAC=2/6/1/1 공중합체의 경우, $30{\sim}90%RH$에서 $1.4\;M{\Omega}{\sim}2.9\;k{\Omega}$의 저항을 보여주었으며 좋은 직선성과 작은 히스테리시스를 보여주었다.

• 센서학회지
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• 제32권5호
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• pp.290-294
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• 2023

Among various types of harmful gases, hydrogen sulfide is a strong toxic gas that is mainly generated during spillage and wastewater treatment at industrial sites. Hydrogen sulfide can irritate the conjunctiva even at low concentrations of less than 10 ppm, cause coughing, paralysis of smell and respiratory failure at a concentration of 100 ppm, and coma and permanent brain loss at concentrations above 1000 ppm. Therefore, rapid detection of hydrogen sulfide among harmful gases is extremely important for our safety, health, and comfortable living environment. Most hydrogen sulfide gas sensors that have been reported are electrical resistive metal oxide-based semiconductor gas sensors that are easy to manufacture and mass-produce and have the advantage of high sensitivity; however, they have low gas selectivity. In contrast, the electrochemical sensor measures the concentration of hydrogen sulfide using an electrochemical reaction between hydrogen sulfide, an electrode, and an electrolyte. Electrochemical sensors have various advantages, including sensitivity, selectivity, fast response time, and the ability to measure room temperature. However, most electrochemical hydrogen sulfide gas sensors depend on imports. Although domestic technologies and products exist, more research is required on their long-term stability and reliability. Therefore, this study includes the processes from electrode material synthesis to sensor fabrication and characteristic evaluation, and introduces the sensor structure design and material selection to improve the sensitivity and selectivity of the sensor. A sensor case was fabricated using a 3D printer, and an Ag reference electrode, and a Pt counter electrode were deposited and applied to a Polytetrafluoroethylene (PTFE) filter using PVD. The working electrode was also deposited on a PTFE filter using vacuum filtration, and an electrochemical hydrogen sulfide gas sensor capable of measuring concentrations as low as 0.6 ppm was developed.

• 마이크로전자및패키징학회지
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• 제11권1호
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• pp.49-57
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• 2004

습도센서의 감습막으로 응용하기 위하여 폴리이온넨계 전해질 잉크를 제조하였다. 감습필름 은 금전극이 인쇄된 알루미나 기판 위에 잉크젯 인쇄 기법을 사용하여 도포 하였다. 또한 methyl methacrylate, acrylic acid, 2-hydroxyethyl methacrylate 그리고 [(2-methacryloyloxy)ethyl)ethyl]trimethylammonium chloride의 공중합체를 합성하였으며, 이것은 침적코팅에 의한 감습막 제조에 사용하였다. 상대습도에 따른 전기적 특성을 측정하였으며 침적코팅에 의한 습도센서와 비교하였다. 습도센서는 상대습도가 증가함에 따라서 저항의 감소함을 보여주었으며 그들의 저항특성은 시료간에 가깝게 일치함을 보여주었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1998년도 춘계학술대회 논문집
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• pp.431-434
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• 1998

Platinum-Cobalt alloy thin films were deposited on Al$_2$O$_3$ substrate by r.f. cosputtering for RTD temperature sensors. We made Pt-Co alloy resistance patterns on the Al$_2$O$_3$ substrate by lift-off method and investigated the physical and electrical characteristics of these films under various conditions (the input power, working vacuum, annealing temperature, thickness of thin films) and also after annealing these films. At input power of Pt : 4.4 W/$\textrm{cm}^2$, Co : 6.91 W/$\textrm{cm}^2$, working vacuum on and annealing conditions of 1000 $^{\circ}C$ and 60 min, the resistivity and the sheet resistive thin films were 15 ${\mu}$$\Omega$$.$cm and 0.5 $\Omega$/$\square$, respectively. The TCR value of Pt-Co a films was measured with various thickness of thin films and annealing temperature. T TCR value is gained under condition 3000${\AA}$ of thin films thickness and 1000$^{\circ}C$ of temperature. These results indicate that Pt-Co alloy thin films have potentiality for the wide temperature ranges.

• 대한기계학회논문집B
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• 제33권8호
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• pp.573-579
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• 2009

A thermal mass air flow sensor, which consists of a micro-heater and thermal sensors on the silicon-nitride thin membrane structure, is micro-fabricated by MEMS processes. Three thermo-resistive sensors, one for the measurement of microheater temperature, the others for the measurement of membrane temperature upstream and downstream of the micro-heater respectively, are used. The micro-heater is operated under the constant temperature difference mode via a real time controller, based on inlet air temperature. Two design models for microfabricated flow sensor are compared with experimental results and confirmed their applicabilities and limitations. The thermal characteristics are measured to find the best flow indicator. It is found that two normalized temperature indicators can be adopted with some advantages in practice. The flow sensor with this control mode can be adopted for wide capability of high speed and sensitivity in the very low and medium velocity ranges.

• 한국구조물진단유지관리공학회 논문집
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• 제5권3호
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• pp.173-180
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• 2001

In the past few years, the nondestructive inspection technology has greatly developed due to the increased necessity to gain a complete understanding of the bridge behavior. Especially, the deformations of bridges contain a lot of informations about its health state. By measuring these deformations it is possible to analyze the loading and aging behavior of the structure. However, the current, methods (such as LVDT, dial gage, optical displacement transducer, etc) are often of changeable application on site and have the limitations of installation. In this paper, the classical beam theory was reviewed and the deflections of structure are estimated using measured strain which is easy to acquire. The applicability of this algorithm is verified by laboratory(simple reinforced concrete beam) and field test. By this test, we proposed correction factor to estimate deflection of reinforced concrete beam after cracking, and analyze about the generation of correction factor. Also fiber optic sensors as well as resistive strain gages were installed in the concrete beams to establish the applicability of fiber optic sensors in the field of civil engineering.

• 센서학회지
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• 제19권6호
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• pp.403-420
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• 2010

Nano and micro structure-based biosensors are promising tool for label-free detection of biomolecular interactions with great accuracy. This review gives a brief survey on nano and micro platforms to sense a variety of analytes such as DNA, proteins and viruses. Among incredible nano and micro structure for bio-analytical applications, the scope of this paper will be limited to micro and nano resonators and nanowire field-effect transistors. Nanomechanical motion of the resonators transducers biological information to readable signals. They are commonly combined with an optical, capacitive or piezo-resistive detection systems. Binding of target molecule to the modified surface of nanowire modulates the current of the nanowire through electrical field-effect. Both detection methods have advantages of label-free, real-time and high sensitive detection. These structures can be extended to fabricate array-type sensors for multiplexed detection and high-throughput analysis. The biosensors based on these structures will be applied to lab-on-a-chip platforms and point-of-care diagnostics. Basic concepts including detection mechanisms and trends in their fields will be covered in this review.