• Journal of Preventive Medicine and Public Health
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• v.6 no.1
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• pp.65-70
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• 1973

The study in the fild of medical instrument has been out of the interest by any of the life scientist in Korea. Especially, the recent developments in the medical electromics are remarkable one. Authors planned this study to ascertain the possibility of setting up the thermister thermometer with available accessories of demestic prouducts including some specific foreign assembly parts. By proper use of the thermister as one of the wheatstone bridge, we could detect tile resistance variations due to the environmental temperature variace. The intensive care for the bridge circuit and compensation scheme was required. The calibration procedure adopted here makes it possible to read the current as the temperature. The temperature range was determined by the examination and construction of the graph of the resistance-temperature variation. The determination of electric current, available ambient-temperature, the reduction of excessive current and self-heating of the thermister were made. Renovation in response-velocity was under taken too. This electronic thermometer was designed and assembled by the circuitry developed in accordance with the maximum availability of domestic products with some foreign-made parts. The result of our experiment showed very stable function and proved to be the most promissing item in the actual application as long as the thermistor thermister is concerned.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.208-211
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• 2005

This paper presents an ultra-low partial discharge(PD) measurement system that has been accepted as a non-destructive method to estimate electrical insulation of low-voltage electric devices. The PD measurement system is composed of a coupling network, a low noise amplifier, and associated electronics. A shielding box is used to make a better condition against electromagnetic interference. A low cut-off frequency of the coupling network was 1MHz(-3 dB). Calibration tests on laboratory set-up have shown that the PD measurement system has a stable sensitivity of 11.4mV/pC. In an application experiment on a low-voltage induction motor(5HP), we could detect 0.77pC level of partial discharge pulse at the applied voltage of AC 664 V$_{peak}$.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.10a
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• pp.436-439
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• 2011

본 논문은 클록 보정회로를 가진 1V 2.56-GS/s 6-bit flash analog-to-digital converter (ADC) 제안한다. 제안하는 ADC 구조에서 아날로그 블록은 단일 T/H와 2단의 프리앰프, 그리고 비교기를 사용된다. 2단의 프리앰프와 비교기의 출력에 옵셋의 크기를 줄이기 위하여 저항 평균화 기법을 적용하였다. 디지털 블록은 quasi-gray rom base 구조를 사용한다. 3입력 voting 회로로 flash ADC에서 발생하기 쉬운 bubble error를 제거하였으며, 고속 동작을 위해 단일 클록을 사용하는 TSPC F/F로 구현한다. 제안하는 flash ADC는 클록 듀티 비를 조절할 수 있는 클록 보정회로를 사용한다. 클록 보정 회로는 비교기 클록 듀티 비를 조절하여 리셋 시간과 evaluation 시간의 비율을 최적화함으로 dynamic 특성을 확보한다. 제안한 flash ADC는 1V 90nm의 CMOS 공정에서 설계되었다. Full power bandwidth인 1.2 GHz 입력에 대하여 ADC 성능을 시뮬레이션을 통해 확인하였다. 설계된 flash ADC의 면적과 전력소모는 각각 $800{\times}400\;{\mu}m^2$와 193.02mW 이다.

• Journal of Institute of Convergence Technology
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• v.1 no.1
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• pp.34-40
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• 2011

In this paper, a hybrid design tool combining one-dimensional(1D) lumped model and three-dimensional computational fluid dynamics(CFD) approach has been developed in order to evaluate the performance of inkjet print head and droplet control process are studied to reduce the deviations between nozzles which affect the size of the printed line for the industrial application of direct writing on printed circuit boards(PCB). 1D lumped model analysis shows that it is useful tool for evaluating performance of an inkjet head by varying the design parameters. The differences in ejected volume and droplet velocity between analytical and experimental result are within 12%. Time sequence of droplet generation is verified by the comparison between 3D analysis result and photographic images acquired by stroboscopic technique. In addition, by applying DPN process, velocity and volume uniformity between nozzles is dramatically improved that the tolerance achieved by the piezoelectric inkjet printhead across the 64 nozzles is 5 to 8%. A printed line pattern is successfully obtained using the fabricated inkjet print head and droplet calibration system.

• Journal of Sensor Science and Technology
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• v.28 no.5
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• pp.284-288
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• 2019

A calibration-free analog neuron circuit is proposed as a viable alternative to the power hungry digital neuron in implementing a deep neural network. The conventional analog neuron requires calibrations because a voltage-mode link is used between the soma and the synapse, which results in significant uncertainty in terms of current mapping. In this work, a current-mode link is used to establish a robust link between the soma and the synapse against the variations in the process and interconnection impedances. The increased hardware owing to the adoption of the current-mode link is estimated to be manageable because the number of neurons in each layer of the neural network is typically bounded. To demonstrate the utility of the proposed analog neuron, a simple neural network with $4{\times}7{\times}3$ architecture has been designed for classifying iris flowers. The chip is now under fabrication in 0.35 mm CMOS technology. Thus, the proposed true current-mode analog neuron can be a practical option in realizing power-efficient neural networks for edge computing.

• Ocean Systems Engineering
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• v.14 no.1
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• pp.53-72
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• 2024

The interaction of the blade of surface-piercing propellers (SPPs) with the water/air surface is a physical phenomenon that is difficult to model mathematically, so that such propellers are usually designed using empirical approaches. In this paper, a newly developed mechanism for measuring the torque of SPPs in an open water circuit is presented. The mechanism includes a single-component load cell and a deformable torque sensor to detect the forces exerted on the propeller. Deformations in the sensor elements lead to changes in the strain gauge resistance, which are converted into voltage using a Wheatstone bridge. The amplified signal is then recorded by a 16-channel data recording system. The mechanism is calibrated using a 6-DoF calibration system and a Box-Behnken design, achieving 99% accuracy through multivariate regression and ANOVA. Finally, the results of performance tests on a 4-blade propeller were presented in the form of changes in the torque coefficient as a function of feed rate. The results show that the new mechanism is 8% more accurate than conventional empirical methods.

• Journal of IKEEE
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• v.16 no.1
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• pp.28-33
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• 2012

Recently, with mobile devices increasing, as a variety of multimedia functions are needed, battery life is decreased. Accordingly the methods for extending the battery life has been proposed. In order to implement these methods, we have to know exactly the status of the battery, so we need a high resolution analog to digital converter(ADC). In case of the existing integrating sigma-delta ADC, it have not convert reset-time conversion cycle to function of resolution. Because of this reason, all digital values corresponding to the all number of bits will not be able to be expressed. To compensated this drawback, this paper propose that all digital values corresponding to the number of bits can be expressed without having to convert reset-time additional conversion cycle to function of resolution by using a up-down counter. The proposed circuit achieves improved SNDR compared to conventional converters simulation result. Also, this was designed for low power suitable for battery management systems and fabricated in 0.35um process.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.2430-2434
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• 2005

Automatic FPC punching instrument for the improvement of working condition and cost saving is introduced in this paper. FPC(flexible printed circuit) is used to detect the contact position of K/B and button like a cellular phone. Depending on the quality of the printed ink and position of reference punching point to the FPC, the resistance and current are varied to the malfunctioning values. The size of reference punching point is 2mm and the above. Because the punching operation is done manually, the accuracy of the punching degree is varied with operator's condition. Recently, The punching accuracy has deteriorated severely to the 2mm punching reference hall so that assembly of the K/B has hardly done. To improve this manual punching operation to the FPC, automatic FPC punching system is introduced. Precise mechanical parts like a 5-step stepping motor and ball screw mechanism are designed and tested and low cost PC camera is used for the sake of cost down instead of using high quality vision systems for the FA. 3D Mechanical design tool(Pro/E) is used to manage the exact tolerance circumstances and avoid design failures. Simulation is performed to make the complete vision based punching machine before assembly, and this procedure led to the manufacturing cost saving. As the image processing algorithms, dilation, erosion, and threshold calculation is applied to obtain an exact center position from the FPC print marks. These image processing algorithms made the original images having various noises have clean binary pixels which is easy to calculate the center position of print marks. Moment and Least square method are used to calculate the center position of objects. In this development circumstance, Moment method was superior to the Least square one at the calculation of speed and against noise. Main control panel is programmed by Visual C++ and graphical Active X for the whole management of vision based automatic punching machine. Operating modes like manual, calibration, and automatic mode are added to the main control panel for the compensation of bad FPC print conditions and mechanical tolerance occurring in the case of punch and die reassembly. Test algorithms and programs showed good results to the designed automatic punching system and led to the increase of productivity and huge cost down to law material like FPC by avoiding bad quality.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.261-267
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• 2011

The test fit has commonly used for the evaluation of the railbed condition, and indirect methods by using the compressional wave are also studied. the direct evaluation method by penetration test has not been studied. For the measurement of in-situ cone tip resistance of the railbed with minimizing the disturbance of the upper railbed. the cone penetrometer with the helical type outer rod(CPH) was developed. The outer rod, which has helical screw, is penetrated through the gravel layer and provides the reaction force for cone penetration testing. the cone tip resistances are measured by the mini cone penetrometer, where diameter is 15mm. For the developing the mini cone, strain gauge installation, circuit configuration, penetration rates and calibration process are considered. For the easy penetration of the screw rod in the field, the reaction force stepping plate and guide column are arranged. The screw rod are penetrated through the gravel layer. And the mini cone was pushed into the subgrade railbed at the penetration rate of 1mm/sec. The penetration test shows that the cone tip resistance increases along the depth. In addition, the subgrade condition is evaluated. This study demonstrates that the CPH may be effectively used for the evaluation of subgrade method any damage of the gravel layer.

• Journal of Sensor Science and Technology
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• v.12 no.1
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• pp.34-43
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• 2003

In this study, we implemented the measurement of pH, $pO_2$, $pCO_2$ of the arterial blood on a portable blood gas analysis system. This system is consist of two parts of hardware and software. The hardware part is divided into a fluidic mechanism and an electronic circuit unit. The system program is composed of operating, washing, correcting, and measuring routines. Both of 1-point and 2-point calibration schemes were used to enhance the accuracy of the measurement. In order to evaluate the performance of the developed system, we measured and performed statistical analysis on the characteristics of the sensing electrode response. As a result, coefficient variation was within 1.12, and maximum error was within 1.298%. We confirmed development possibility of portable blood gas analyzer.