• Journal of the Korean GEO-environmental Society
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• v.24 no.3
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• pp.5-14
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• 2023

The dry unit weight of the soil can be obtained by measuring the weight of the oven dried soil. According to the Korean Industrial Standards (KS F), oven dried soil at 110±5℃ continuously increases in weight when exposed to air. However, there is no regulation on the weight measurement time of oven dried soil, making it difficult to accurately measure the dry weight. In this study, a method to easily determine the dry weight was presented through the analysis of the weight singularity that appears during weight measurement. The weight singularity represents the smallest value among the measured weights, and is the weight at which the effect of moisture absorption in the air of the sample is minimized. In the course of the experiment, a container was selected using a statistical analysis method, and a photograph of the soil samples were presented using an optical microscope. In addition, the temperature of the weight singularity was measured using a non-contact infrared thermometer. As a result of analyzing the weight singularity of six types of soil, including Jumunjin sand, Naeseong stream sand, Yecheon weathered granite soil, Jeju sand, Sabkha sand, and Ulleung sand, the weight singularity of oven dried sample appeared between 8 and 27 seconds after weight measurement, and the temperature ranged from 103.4 to 108.13℃. The weight decrease rate of the singularity was 0.0066 to 0.0085% depending on the soil samples.

• Journal of the Microelectronics and Packaging Society
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• v.31 no.2
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• pp.63-68
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• 2024

With the increasing use of transparent displays and flexible devices, polymer substrates offering excellent flexibility and strength are in demand. Since polymers are sensitive to heat, precise temperature control during the process is necessary. The study proposes a temperature measurement system for the laser processing area within the polymer base, aiming to address the drawbacks of using these polymer bases in laser-based selective processing technology. It presents the possibility of optimizing the process conditions of the polymer substrate through local temperature change measurements in the laser processing area. We developed and implemented the PDPT (Photodiode-based Planck Thermometry) to measure temperature in the laser-processing area. PDPT is a non-destructive, contact-free system capable of real-time measurement of local temperature increases. We monitored the temperature fluctuations during the laser processing of the polymer substrate. The study shows that the proposed laser-based temperature measurement technology can measure real-time temperature during laser processing, facilitating optimal production conditions. Furthermore, we anticipate the application of this technology in various laser-based processes, including essential micro-laser processing and 3D printing.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2017.04a
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• pp.156-156
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• 2017

Most crop damages have been occurred by vermin(e.g., wild birds and herbivores) during the period between seeding and the cotyledon level. In this study, to minimize the damage by vermin and acquire the benefits such as protection against weeds and maintenance of water content in soil, immediately vinyl mulching after seeding was devised. Vinyl mulching has been generally covered with black color vinyl, that crop seeding locations cannot be detected by visible light range. Before punching vinyl, non-contact and non-destructive methods that can continuously determine the locations are necessary. In this study, a crop position detection method was studied that uses infrared thermal image sensor to determine the cotyledon position under vinyl mulch. The moving system for acquiring image arrays has been developed for continuously detecting crop locations under plastic mulching on the field. A sliding mechanical device was developed to move the sensor, which were arranged in the form of a linear array, perpendicular to the array using a micro-controller integrated with a stepping motor. The experiments were conducted while moving 4.00 cm/s speed of the IR sensor by the rotational speed of the stepping motor based on a digital pulse width modulation signal from the micro-controller. The acquired images were calibrated with the spatial image correlation. The collected data were processed using moving averaging on interpolation to determine the frame where the variance was the smallest in resolution units of 1.02 cm. For this study, the spline method was relatively faster than the other polynomial interpolation methods, because it has a lower maximum order of formulation when using a system such as the tridiagonal linear equation system which provided the capability of real-time processing. The temperature distribution corresponding to the distance between the crops was 10 cm, and the more clearly the leaf pattern of the crop was visually confirmed. The frequency difference was decreased, as the number of overlapped pixels was increased. Also the wave pattern of points where the crops were recognized were reduced.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.28 no.1
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• pp.57-64
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• 2010

Measurements of deflection in load testing of structures are typically obtained with contact instrumentations such as LVDT (Linear-Variable Differential Transformer). LVDT only measure 1-dimensional deformation and in destructive testing is damage to instrumentation, thus prohibiting deflection when the beam is close to failure. Measurements of deflection using non-metric digital cameras are useful for load testing because there are very little cost or beam failure except for cheap targets and measurements in 3-dimensional deflection can obtained rapidly. In this research, deflection of concrete beam was measured using Nikon D80 DSLR camera, and the accuracy was evaluated with comparing the outputs to the LVDT measurements. The results show that the accuracy of terrestrial photogrammetric measurements are ${\pm}$0.5mm, ${\pm}$0.5mm, ${\pm}$0.6mm for each X, Y, Z directions, and the RMSE of comparison to LVDT is ${\pm}$0.57mm.

• Journal of Electrical Engineering and Technology
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• v.10 no.1
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• pp.364-371
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• 2015

In this study, we developed a feasible structure of a textile-based inductive sensor using a machine embroidery method, and applied it to a non-contact type vital sign sensing device based on the principle of magnetic-induced conductivity. The mechanical heart activity signals acquired through the inductive sensor embroidered with conductive textile on fabric were compared with the Lead II ECG signals and with respiration signals, which were simultaneously measured in every case with five subjects. The analysis result showed that the locations of the R-peak in the ECG signal were highly associated with sharp peaks in the signals obtained through the textile-based inductive sensor (r=0.9681). Based on the results, we determined the feasibility of the developed textile-based inductive sensor as a measurement device for the heart rate and respiration characteristics.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.4
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• pp.332-337
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• 2018

This paper presents the design optimization of fuel sensor location used to measure remained fuel amount in aircraft conformal fuel tank. The conformal fuel tank is utilized to expand the mission range in airplane, and the sensor location is a critical design variable determining the measurement accuracy. In this work, the sensor location is optimized to minimize unmeasurable fuel amount due to non-contact between fuel and sensor. The simplified model is prepared from the conformal fuel tank CATIA model, and the unmeasurable fuel amount is calculated. Then, the optimization is performed using MATLAB optimization solver. The optimized sensor location is validated by comparing with the location obtained using parametric study.

• Journal of Biomedical Engineering Research
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• v.28 no.2
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• pp.310-315
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• 2007

The axial-flow type blood pump(XVAD) which has been developed in our group consists of mechanical parts (an impeller, a diffuser and a flow straightener) and electrical parts (a motor and a magnetic bearing). The magnetic bearing system fully levitates the impeller to remove mechanical coupling with other parts of the pump with constant gap, which needs non-contact type gap sensing. Conventional gap sensors are too large to be adopted to the implantable axial -flow type blood pump. Thus, in this paper, the compact eddy current type gap sensor system proper for the implantable axial-flow type blood pump was developed and its performance was evaluated in vitro. The developed eddy current type gap sensor system is a transformer type and has a differential probe. Sensor coil(probe) has small dimensions(6 mm diameter, 2 mm thickness) and its optimal inductance was determined as 0.068 mH for the measurement range of $0\sim3mm$. It could be manufactured with 130 turns of the 0.04 mm diameter copper coil. The characteristics of the developed eddy current type gap sensor system was evaluated by in vitro experiment. At experiment, it showed satis(actory performance to apply to the magnetic bearing system of the XVAD. It could measure the gap up to 3mm, but the linearity was decreased at the range of $1.8\sim3.0mm$. Moreover, it showed no difference in different media such as the water and the blood at the temperature range of $35\sim40^{\circ}C$.

• Journal of the Korea Concrete Institute
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• v.19 no.1
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• pp.3-9
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• 2007

With a growing concern about the state of infrastructure worldwide, the demand for the development of reliable nondestructive testing techniques (NDT) is ever increasing. Among possible NDT techniques, microwave method is proven to be effective in fast and non-contact inspection of concrete structures and inclusions inside concrete. It is also found that the microwave method has a potential in detecting the delamination between fiber reinforced polymers (FRP) plate and concrete. On the other hand, ultrasonic method can be another way to find the delamination. In this paper, the research work needed for the development of a reliable microwave method and ultrasonic method is studied in the measurements of concrete specimens reinforced with FRP. Concrete specimens are made with FRP and artificial delamination inside. A microwave measurement system with hom antennas with high center frequency and broad frequency bandwidth are used to image inside concrete specimens for the detection of debonding between concrete and FRP. Also, ultrasonic method is used for the same condition. Both results are compared with each other.

• Journal of the Korean Society for Nondestructive Testing
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• v.32 no.2
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• pp.177-184
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• 2012

An optical defect detection method using ESPI(electronic speckle pattern interferometry) is proposed. ESPI is widely used as a non-contact measurement system which show deformation and phase map in real time. ESPI can be divided as the in-plane, out-of-plane and shearography by operation principle and target object and also divided with bulk type and optic fiber type by the optic configurations. This paper is focused on optic fiber type out-of-plane ESPI, which has the following advantages: (1) low cost; (2) reduction of the unreliable factors generated by separated optic components; (3) simplification of the optic configuration; (4) great reduction of volume; (5) flexibility, to be easily designed into different structures to adapt to inaccessible environments such as pipeline cavity and so on.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.1841-1844
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• 2009

일반 하천에서의 유량측정 방법은 하천 조건에 따라 다르다. 전통적인 방법으로는 구조물에 의한 방법, 유속계 측정에 의한 유속-면적법, 부자에 의한 방법, 그리고 희석법 등이 있다. 그러나 이러한 방법들은 측정 위험성을 가지고 있다. 홍수시 발생되는 고유속과 심한 난류, 거대한 부유물질들은 하천 접근에 어려움을 가져오고, 측정 기기의 파손 위험성뿐만 아니라 인명피해까지 발생시킬 가능성이 있다. 최근 기존 방법들의 문제점을 해결하기 위하여 음파, 초음파, 레이더 등을 이용한 유량 측정 방법과 장비들이 개발되었다. 본 연구에서 사용한 레이더 유속계는 하천의 표면유속을 측정하는 비접촉식 센서로 홍수기 전 미리 유속 측정 단면 측량을 실시한다면 홍수시에도 비교적 신속하고 안전하게 유속을 측정할 수 있다. 따라서 본 연구에서는 레이더 유속계를 충청북도 괴산군 달천에 위치한 수전교에 설치하여 괴산댐 방류량 및 동시유량 측정 성과와 비교하였다. 2007년 7월부터 2008년 8월까지 $36m^3/s\;\sim\;821m^3/s$의 사상에서 총 10회 측정한 결과, 레이더 유속계를 사용하여 측정한 유량의 상대오차는 댐방류량 대비 -3.3% $\sim$ 27.5%로 나타나 평균11.8%의 상대오차를 보였다. 레이더 유속계 측정과 동시에 실시한 유속-면적법 측정, ADCP법 측정의 상대오차는 각각 평균 5.7%, 6.5%로 나타난 것과 비교한다면 다소 높은 오차를 보였다. 그러나 측정 시간의 경우 수위에 따라 다소 차이는 있지만 레이더 유속계를 이용하면 30분 정도의 시간이 소요되었으며, 유속면적법은 1시간 이상, ADCP법은 40분의 시간이 소요되었다. 이와 같이 레이더 유속계는 다른 방법에 비해 정확성은 다소 떨어지지만 측정 속도와 안정성 면에서는 우수하다고 판단된다. 문제점으로 지적되는 정확도 측면의 경우 레이더 유속계로 측정되는 표면유 속과 평균 유속 사이의 보정계수 문제를 보완한다면 보다 정확한 측정이 가능할 것으로 판단된다.