• Current Optics and Photonics
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• v.7 no.6
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• pp.761-765
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• 2023

We analyzed the absorption spectra of acetone in the 3.37 ㎛ mid-infrared range using the off-axis integrated cavity output spectroscopy technique to develop a real-time, in-line breath analysis device. The linear relationship between acetone concentration and absorption increase was confirmed as 0.32%/ppm, indicating that the developed device allows for a quantitative analysis of acetone concentration in exhaled breath. To further confirm the feasibility of using our device for breath analysis, we measured the acetone concentration of human breath samples at the sub-ppm level.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.04a
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• pp.480-485
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• 2002

The purpose of this paper is the development of guidance algorithm for a mobile robot which is used to acquire the position and state information of the pipe defects such as crack, damage and through hole. The data used for the algorithm is the range data obtained by the range sensor which is based on an optical triangulation method. The sensor, which consists of a laser slit beam and a CCD camera, measures the 3D profile of the pipe's inner surface. After setting the range sensor on the robot, the robot is put into a pipe. While the camera and the LSB sensor part is rotated about the robot axis, a laser slit beam (LSB) is projected onto the inner surface of the pipe and a CCD camera captures the image. From the images the range data is obtained with respect to the sensor coordinate through a series of image processing and applying the sensor matrix. After the data is transformed into the robot coordinate, the position and orientation of the robot should be obtained in order to guide the robot. In addition, analyzing the data, 3D shape of the pipe is constructed and the numerical data for the defects of the pipe can be found. These data will be used for pipe maintenance and service.

• Journal of the Korean Society for Precision Engineering
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• v.34 no.1
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• pp.53-58
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• 2017

A fine stage is developed for the 3-DOF error compensation of a linear axis in order to improve the positioning accuracy. This stage is designed as a planar parallel mechanism, and the joints are based on a flexure hinge to achieve ultra-precise positioning. Also, the effect of Abbe's offsets between the measuring and driving coordinate systems is minimized to ensure an exact error compensation. The mode shapes of the designed stage are analyzed to verify the desired 3-DOF motions, and the workspace and displacement of a piezoelectric actuator (PZT) for compensation are analyzed using forward and inverse kinematics. The 3-DOF error of a linear axis is measured and compensated by using the developed fine stage. A marked improvement is observed compared to the results obtained without error compensation. The peak-to-valley (PV) values of the positional and rotational errors are reduced by 92.6% and 91.3%, respectively.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.221-224
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• 2012

This paper presents a CMOS interface circuit for MEMS acceleration sensor. It consists of a capacitance to voltage converter(CVC), a second-order switched-capacitor (SC) integrator and comparator. A bandgap reference(BGR) has been designed to supply a stable bias to the circuit and a ${\Sigma}{\Delta}$ Modulator with chopper - stabilization(CHS) has also been designed for more suppression of the low frequency noise and offset. As a result, the output of this ${\Sigma}{\Delta}$ Modulator increases about 10% duty cycle when the input voltage amplitude increases 100mV and the sensitivity is x, y-axis 0.45v/g, z-axis 0.28V/g. This work is designed and implemented in a 0.35um CMOS technology with a supply voltage of 3.3V and a sampling frequency of 3MHz sampling frequency. The size of the designed chip including PADs is $0.96mm{\times}0.85mm$.

• The Journal of the Korea institute of electronic communication sciences
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• v.12 no.6
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• pp.1233-1242
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• 2017

Various attempts have been made to prevent crime risk. One of the cases where outdoor pedestrians are attacked by criminals is the abnormal health condition. When a mental or mental condition that can not sustain normal walking due to drunkenness is exposed, the case of being a crime is revealed through crime case analysis. In this study, we propose a method for estimating the state of an individual that can be detected in outdoor activities. In order to avoid the inconvenience of installing a separate terminal for event information transmission of sensors and sensors, it is possible to estimate an abnormal state by using a 3-axis acceleration sensor built in a smart phone. The state of the user can be estimated by analyzing the momentum of the user and analyzing it with the passage of time. It is possible to distinguish the flow of time at regular intervals, to recognize the activity patterns in each time band, and to distinguish between normal and abnormal. In this study, we have evaluated the total amount of kinetic energy and kinetic energy in each direction of the acceleration sensor and the Fourier transformed value of the total energy amount to distinguish the abnormal state.

• Journal of Mechanical Science and Technology
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• v.16 no.7
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• pp.927-934
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• 2002

The HANARO ( High-flux Advanced Neutron Application Reactor) has been operated since 1995. The Cold Neutron (CN) hole was implanted in the reflector tank from the design stage. Before a vacuum chamber and a moderator cell for the cold neutron source are installed into the CN hole, it is necessary to measure exactly the size of the inside diameter and thickness of the CN hole to prevent the interference problem. Due to inaccessibility and high radiation field in the CN hole, a mechanical measurement method is not permitted. The immersed ultrasonic technique is considered as the best way to measure the thickness and the diameter of the CN hole. The 4-Axis manipulator was designed and fabricated for locating the ultrasonic sensors. The transducer of an ultrasonic sensor having 10 MHz frequency leads to high resolution as much as 0.03mm. The inside diameter and thickness of 550 points of the CN hole were measured using 2 channel ultrasonic sensors. The results show that the thickness and inside diameter of the CN hole is in the range of 3.3∼6.7mm and 156∼ 165mm, respectively. This data will be a good reference for the design of the cold neutron source facility.

• Journal of Electrical Engineering and Technology
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• v.10 no.3
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• pp.1048-1057
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• 2015

This paper proposes a sensorless speed control algorithm for parallel-connected dual Surface-mounted Permanent Magnet Synchronous Motors (SPMSMs) fed by a single inverter. For stable parallel operation of synchronous motors with a single inverter, each motor has to be constantly kept in the synchronization state regardless of load torque. If the master motor with the larger load is controlled, the synchronous state will be maintained. Therefore, detection of the master motor is essential. Conventionally, the master motor is determined by comparing the rotor position error from the relation between the back-EMF for torque angle and the flux position; consequently, the position sensor is deemed essential for finding the rotor position. The parallel sensorless speed control method proposed in this paper uses no position sensor, instead it compares the flux-axis current from the connection between the back-EMF for torque angle and current in unbalanced load conditions. The results of simulation and experiment conducted verify the efficacy of the proposed method.

• KIPS Transactions on Computer and Communication Systems
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• v.7 no.8
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• pp.211-218
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• 2018

In this study, we propose an algorithm to detect eating activity and estimation mealtime using 6-axis inertial sensor. The eating activity is classified into three types: food picking, food eating, and lowering. The feature points of the gyro signal are selected for each gesture, and the eating activity is detected when each feature point appears in the sequence. Morphology technique is used to post-process to detect meal time. The proposed algorithm achieves the accuracy of 94.3% and accuracy of 84.1%.

• Journal of Biosystems Engineering
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• v.40 no.1
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• pp.28-34
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• 2015

Purpose: This study aimed to install an RTK-GPS (Real Time Kinematic-Global Positioning System) and IMU (Inertial Measurement Unit) on a tractor used in a farm to measure positions, pasture topography, posture angles, and vibration accelerations, translate the information into maps using the GIS, analyze the characteristics of grass harvesting work, and establish new technologies and construction standards for pasture infrastructure improvement based on the analyzed data. Method: Tractor's roll, pitch, and yaw angles and vibration accelerations along the three axes during grass harvesting were measured and a GIS map prepared from the data. A VRS/RTK-GPS (MS750, Trimble, USA) tractor position measuring system and an IMU (JCS-7401A, JAE, JAPAN) tractor vibration acceleration measuring systems were mounted on top of a tractor and below the operator's seat to obtain acceleration in the direction of progression, transverse acceleration, and vertical acceleration at 10Hz. In addition, information on regions with bad workability was obtained from an operator performing grass harvesting and compared with information on changes in tractor posture angles and vibration acceleration. Results: Roll and pitch angles based on the y-axis, the direction of forward movements of tractor coordinate systems, changed by at least $9-13^{\circ}$ and $8-11^{\circ}$ respectively, leading to changes in working postures in the central and northern parts of the pasture that were designated as regions with bad workability during grass harvesting. These changes were larger than those in other regions. The synthesized vectors of the vibration accelerations along the y-axis, the x-axis (transverse direction), and the z-axis (vertical direction) were higher in the central and northwestern parts of the pasture at 3.0-4.5 m/s2 compared with other regions. Conclusions: The GIS map developed using information on posture angles and vibration accelerations by position in the pasture is considered sufficiently utilizable as data for selection of construction locations for pasture infrastructure improvement.

• Journal of Power System Engineering
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• v.19 no.3
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• pp.36-41
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• 2015

The true north-finding equipment utilizing gyro sensor is used for INS(Inertial Navigation System) and has an increasing preference for gyro compass system due to compact size, lightening, low power and price. The purpose of this experiment is to research gyro compass system providing high performance in the field of manned or unmanned gyro compass system which proposes the accuracy of 1% utilizing experimented equipment at true north of the earth. Unlike the conventional system, the proposed gyro sensor system indicates to be applied in the various and specific equipment using multiple technique and method.