• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1842-1846
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• 2008

This work reports development of novel liquid-level sensors based on the $3{\omega}$ method. The sensors determine the liquid level by measuring the thermal response as in the conventional hot-wire technique. However the sensors employ an AC heating method to enhance the sensitivity, noise resistance and time response. Also, the microfabricated thin-film structure of the sensor provides mass-producibility as well as improved sensor performance owing to the increase in the surface-volume ratio of the sensor. Two different types of the sensor are developed: one for point detection of the fluid phase and the other for monitoring continuous variation of liquid level. Notable is that the performance of the sensor is not considerably affected by the liquid flow.

• Journal of Power System Engineering
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• v.21 no.5
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• pp.71-78
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• 2017

The purpose of this study is to propose the basic data for the development of a sensor capable of simultaneously measuring the liquid-level, concentration and temperature of a urea tank using ultrasonic and electrical conductivity sensors for diesel vehicles with a urea-SCR system. It was found that the liquid-level of the urea tank using the ultrasonic sensor showed a good linearity with the actual liquid-level, and the urea concentration maintained good linearity in the range of 32.5 wt% to 10 wt%. It was an effective measurement of urea concentration to use the electrical conductivity sensor in the temperature range of $-10{\sim}22^{\circ}C$ and to use the ultrasonic sensor at $22^{\circ}C$ or more. Simultaneous measurement of concentration, liquid-level and temperature of the urea tank will be possible by attaching the electrical conductivity sensor and the ultrasonic sensor (split-type) to one sensor together.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.7
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• pp.778-783
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• 2013

Measurement of liquid level in storage and processing vessels, tanks, wells, reservoirs and hoppers is commonly needed. The several different ways to measure the liquid level of oil or water tank have been provided such as an electrostatic capacity, a supersonic waves and an optical science etc. In the study, we have constructed the stable and efficient measurement system to measure the level of liquid at real-time and to get accurate measurement of the maximum and minimum level of the tank. For this purpose, we suggest double sensing methods by adopting both capacitive and optical sensing. The experimental results, presented in this paper, illustrate the effectiveness of the proposed method under different sensing methods.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.24 no.4
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• pp.129-134
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• 2024

In this paper, This paper is a liquid droplet discharge system using a water level sensor that can linearly detect changes in water level through experiments with an infrared sensor, a laser sensor, an ultrasonic sensor, and a capacitance sensor. SMPS, regulator 5V, and LDO 3.3V were designed for power supply. A water level sensor input ADC circuit and microprocessor were used. Solenoid valve control, pump output control unit for positive/negative pressure generation, CAN, Ethernet, UART communication, and USB for industrial communication were used. The change in pressure was confirmed through the change in water level, the change in pressure was minimized, and a system for discharging liquid droplets was implemented.

• Journal of information and communication convergence engineering
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• v.6 no.2
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• pp.207-212
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• 2008

There are several sensors in the liquid cargo ship. In the liquid cargo ship, we can get values from various sensors that are level sensor, temperature sensor, pressure sensor, oxygen sensor, VOCs sensor, high overfill sensor, etc. It is important to guarantee the reliability of sensors. In order to guarantee the reliability of sensors, we have to study the diagnosis of sensor fault. The technology of smart sensor is widely used. In this paper, the technology of smart sensor is applied to diagnosis of level sensor fault for liquid cargo ship. In order to diagnose sensor fault and find the sensor position, in this paper, we proposed algorithms of diagnosis of sensor fault using independent sensor diagnosis unit and self fault diagnosis using sensor modeling. Proposed methods are demonstrated by experiment and simulation. The results show that the proposed approach is useful. Proposed methods are useful to develop smart level sensor.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.2
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• pp.330-335
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• 2009

A fiber-optic liquid level sensor based on bending cantilever beam has been proposed. A fiber Bragg grating(FBG) embedded in the cantilever beam is used to sensing elements. The basic concept is elongation and constriction of the FBG corresponding to the liquid level variation. The best FBG position on the cantilever for obtaining the high sensitivity was 4 cm from the fixing point. When the liquid level moves up and down vertically, the Bragg wavelength is linearly shifted. But, the wavelength sensitivity of the FBG installed on the upper side of cantilever was four times better than that of the FBG equipped in the lateral side due to the difference of unit strain applied to the FBG. Intensity demodulation using the low-cost edge filter is used to interrogate the Bragg wavelength through converting the wavelength signals into the optical intensity ones. Experiment results show that the electrical output is exponentially proportional to the liquid level. But, it should be overcome for applying to the ships.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.95.1-95
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• 2002

<1. New level meter inside the fuel tank> Ultrasound level sensors are widely applied as level meters of liquid tank. Measurement instrument of level between water and fuel is developed. Since the fuel is inflammable, the sensor system doesn't allow to include any electric circuit inside the fuel tank. The optical cable sensor can satisfy this explosive condition. The measurement method with ultrasonic sensor is attached on the tank wall or tank manhole lid. The pressure sensor can't be applied inside the gasoline fuel tank. An ultra-sonic sensor doesn't detect a enough signal reflected from water level deep under gasoline fuel. The pressure sensor is difficult to measure the height o...

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.1073-1078
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• 2003

This paper presents the vibration characteristics of a cantilever beam in contact with a fluid using a PZT actuator and PVDF film. dynamic behaviors of a flexible beam-water interaction system are examined. The effect of the liquid level on free vibration of the composite beam in a partially liquid-filled circular cylinder is investigated. The coupled system is subject to an undisturbed boundary condition un the fluid domain. In the vibration analysis of a wetted beam. the decoupled analyses between beam and fluid have been conventionally employed by considering first the composite beam vibration in the all and secondly Performing the correction taking account for surrounding fluid effects. That is, this investigation was to look at how natural frequencies, mode shapes. and damping are affected by liquid level variations. The signals from the sensor according to the applied input voltage are digitalized and filtered in order to obtain the dynamic characteristics of the composite beam in contact with fluid. It was found that the coupled natural frequencies decreased with the fluid level for the identical composite beam due to added mass effect. In case of the free-free boundary condition, the natural frequency gently decreased at fluid water level between 20% and 80% in the first tending mode and we found out the bends of stair shape for added mass effect of the fluid.

• Journal of the Korean Institute of Intelligent Systems
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• v.18 no.3
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• pp.341-346
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• 2008

This paper is to develop a monitoring system with diagnosis for smart cargo sensors that is for management and maintenance of the liquid cargo ships. The main goal of the system is to achieve the total automation system of the cargo sensor. By this study, the active smart sensor for the liquid cargo ships is designed and developed that guarantees high-confidence, stability, and durability. The proposed system consists of a monitoring part of the steam pressure, high-level monitoring, over flowing monitoring, gas monitoring, and tank temperature monitoring. The signals transferred from each unit system are used for sensor diagnosis based on confidence and accuracy. Finally, in this study, the total supervisory monitoring system is developed to maintain and manage the cargo effectively based on fault diagnosis and prognosis of the each sensor system.

• The KSFM Journal of Fluid Machinery
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• v.18 no.6
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• pp.57-62
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• 2015

The test of comparing liquid flow calibration system (approved by KOLAS) for accuracy and structure change test was performed in the test bed in order to evaluate the typical characteristics of the electromagnetic flow meters and parshall flume that are generally used in the water discharging facilities. The results of the accuracy comparing test with liquid flow calibration system showed the error of less than 2%. Pharshall plume got error up to -8.3% (low flow) from the flow rate test, but less than 4% from the accumulated flow test because of offset error at high flow rate and low flow rate. Evaluation of structual change test was tested with only parshall flume using structure and it consisted of installation angle (parshall flume and level sensor) and position change. Installation angle, water level sensor angle and position changing test for parshall flume had errors of 3.1%~-9.2%, 0.4%~-5.6% and 0.2%~1.3% respectively. Especially, the error showed the largest increase when the water level sensor measured the point of decreased flow by the structure change. Therefore, error factors (change of straight pipe length, installation of obstacle or effect of foreign substances on water level sensor) that can often occur in the field should be derived and the research for optimized installation method should be carried out continuously.