• Journal of Magnetics
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• 제22권2호
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• pp.220-226
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• 2017

SNR (signal to ratio) is a criterion for providing objective information for evaluating the performance of a magnetic resonance imaging device, and is an important measurement standard for evaluating the quality of MR (Magnetic Resonance) image. The purpose of our study is to evaluate the correct SNR measurement for multi-channel coil and parallel imaging. As a result of research, we found that both T1 and T2 weighted images show the narrowest confidence interval of the method recommended by NEMA (The National Electrical manufacturers Association) 1 having a single measurement method, whereas the ACR (American College of Radiology) measurement method using a multi-channel coil and a parallel imaging technique shows the widest confidence interval. There is a significance in that we quantitatively verified the inaccurate problems of a signal to noise ratio using a ACR measurement method when using a multi-channel coil and a parallel imaging technique of which method does not satisfy the preconditions that researchers could overlook.

• Progress in Superconductivity
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• 제12권2호
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• pp.124-128
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• 2011

We have developed a high-$T_C$ SQUID magnetometer system to measure magnetocardiograms of laboratory rats. White noise of the measurement system was about 50 fT/$Hz^{1/2}$ when measured in a magnetically shielded box. We optimized the measurement position to obtain clear MCG wave from rat's small heart by using grid measurements. With the optimization, the MCG signal was successfully detected with the peak amplitude of about 50 pT. We could observe well defined P-, QRS-, and T-wave from the rat MCG. The results suggest that the developed system has a strong potential to monitor the progress of heart disease model using laboratory rat.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2008년도 추계학술대회 논문집
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• pp.254-257
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• 2008

For crystalline slags, of which the viscosity rapidly increases at $T_{cv}$ due to the formation of crystalline phases, the Tcv is affected by measurement conditions. In this study, we investigated the effect of cooling rate, and alumina dissolution on the determination of $T_{cv}$. Using synthetic slag samples based on the composition of Alaska Usibelli slag, $T_{cv}$ were determined under a constant cooling rate of $2^{\circ}C$/min, and under rapid cooling with holding time to allow the slag to reach thermal and rheological equilibrium. The effect of alumina dissolution was investigated using platinum lined crucibles. The constant cooling resulted in lower $T_{cv}$ by $33^{\circ}C$ as compared to the equilibrium measurements. Under $2^{\circ}C$/min cooling, the blocking alumina dissolution resulted in lower $T_{cv}$ by $23^{\circ}C$. When the $T_{cv}$ was measured under $2^{\circ}C$/min cooling using an alumina crucible, therefore, the effects of a constant cooling is somewhat offset by the alumina dissolution effect, and bring the measured value closer to the true value.

• 대한핵의학회지
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• 제9권2호
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• pp.1-11
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• 1975

The serum concentrations of thyrotropin (TSH) were measured by means of radioimmunoassay, in 98 cases of normal controls, 51 cases of hyperthyroidism, 80 cases of primary hypothyroidism and 4 cases of secondary hypothyroidism to evaluate the diagnostic significance in various functional states of the thyroid. The obtained data were analyzed in correlation with other thyroid function test values in various phases of the functional thyroid diseases. The results were as follows: 1) The serum TSH concentration in normal control group was $<1.3{\sim}8.0{\mu}U/ml$. 2) The measurement of serum TSH was more significant in diagnostic accuracy compared with that of serum $T_4(75.0{\pm}12.2%)$. Free $T_4$ Index ($64.2{\pm}15.2%$), serum $T_3(41.0{\pm}21.0%)\;or\;T_3$ resin uptake ($41.1{\pm}15.8%$) in evaluation of primary hypothyroidism. 3) In case of overt hypothyroidism, the serum TSH and $T_4$ were both abnormal, compatible with the clinical diagnosis, while in case of preclinical or mild hypothyroidism, the serum $T_4(41.2{\pm}23.8%)\;or\;50.0{\pm}25.0%)$ was much less reliable than serum TSH. 4) In the treatment of primary hypothyroidism with desiccated thyroid, the administration of 1 grain of the hormone per day was sufficient to suppress the serum concentration of TSH to normal range. It showed that the measurement of serum TSH concentration was a significant criteria in evaluating the efficiency of the treatment of hypothyroidism. 5) The measurement of serum TSH concentration is a very significant method in the early detection of hypothyroidism induced during or after the treatment of the hyperthyroidism with antithyroid drugs or radioactive Iodine ($^{131}I$).

• 한국결정학회지
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• 제7권1호
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• pp.73-80
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• 1996

단일 온도대역 수평 Bridgman(1-T HB)법에 의해 2인치 직경의 GaAs 단결정을 성장시키기 위하여 그 장치를 설계·제작하였고, undoped, Si-doped 및 Zn-doped 단결정을 성장하였다. 단결정성의 측면에서 성장횟수별 비로 0.73의 단결정성을 보였고, 격자결함 밀도(etch pit density)는 n-type의 경우 평균 5,000/cm2, p-type의 경우 10,000/cm2, 그리고 undoped의 경우 20,000/cm2 정도를 보였다. 한편 undoped GaAs 단결정의 경우, Hall 측정에 의한 carrier 농도가 ∼1×1016/cm3인 것으로 나타나 기존의 이중 온도대역(2-T : double temperature zone) 또는 삼중 온도대역(3-T : three temperature zone) 수평 Bridgman 방식에 비하여 Si 유입량이 절반 수준인 것으로 측정되었다. 따라서 1-T HB 방식에 의하여 2-T나 3-T HB 방법보다 나은 수율을 갖고 더 순도가 높은 GaAs 단결정을 성장시킬 수 있었다.

• 한국수자원학회논문집
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• 제53권7호
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• pp.507-519
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• 2020

본 연구에서는 지각운동 모니터링과 지진발생 및 예측에 활용가능한 라돈 측정시스템을 개발하였으며, 라돈 측정시스템의 시범운영 결과와 지진발생 사례를 분석하였다. 첫 번째로, 개발된 라돈 측정시스템은 NB-IoT 라돈 측정기기, 데이터센터, 자료분석 및 자료제공 서버로 구성되며, NB-IoT를 활용하므로 측정된 자료의 원격전송이 가능하기 때문에 이 시스템은 무인 지하수관측소에 설치 및 운영에 매우 적합하다. 두 번째로 개발된 라돈 측정기기를 김포지역 지하수관측소에서 2019년 5월부터 7월까지 시범운영하였다. 측정된 라돈값을 지하수위와 전기전도도 측정자료와 비교하였으며, 본 연구에서 개발한 라돈 측정기기가 상용화하는데 어느 정도 가능성이 있음을 확인하였다. 마지막으로 2019년 11월부터 2020년 2월까지 3개 지진발생 사례와 Test-bed인 포항지역 지하수관측소에 설치된 NB-IoT 라돈 측정기기의 일단위 라돈 측정값, 일단위 지하수위, 일단위 전기전도도의 변동성을 비교·분석하였다. 분석결과, 지진발생이 라돈, 지하수위, 전기전도도와 어느 정도 상관관계가 있음을 확인하였으며, 본 측정자료가 향후 지진모니터링 및 예측에 도움이 되는 기초자료 제공이 가능함을 확인하였다

• 한국전자통신학회논문지
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• 제17권2호
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• pp.229-236
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• 2022

본 논문에서는 5G 무선국 검사에 있어, 측정 시간 단축을 위한 8T8R 콤바이너를 활용한 무선국 검사 방법에 관하여 연구하였다. 5G 무선국 검사는 배열된 안테나 수에 대응하는 RF(: Radio Frequency) 출력 신호를 개별적으로 측정해야 한다. 하지만, 본 연구에서는 개별 채널 측정 결과와 8T8R을 이용한 측정값 비교를 통해 기존 방식을 시간적으로 단축할 수 있는 5G 무선국 검사 방법을 제시하였다. 연구 결과 8T8R 콤바이너를 이용하는 경우, 정확한 무선국 검사를 수행할 수 있을 뿐만 아니라, 기존방식의 소요 시간을 1/8으로 줄일 수 있었다.

• International Journal of Korean Welding Society
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• 제1권2호
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• pp.45-50
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• 2001

This paper presents application of neutron diffraction technique to the measurement of residual stresses in the T-type 20 m thick welded stainless steel plates(100$\times$50 $mm^2$ and 50$\times$50 $mm^2$). The High Resolution Powder Diffractormeter of the Korea Atomic Research Institute was utilized in the measurement. The power of nuclear reactor was 24 MWt and the measured reflection in the 220 plane (2$\theta$）was $92.66^{\circ}$. Poisson ratio of 0.265 and elastic constant of 211 GPa were applied to the calculation of stresses and strains. Three directional components such as normal, transverse, and longitudinal stresses were measured. The results showed that three components were tensile and became compressive along the y axis in the zone away from the welded center. The compressive stresses became tensile in the zone away from the center line of x axis. This may be due to the balance effect caused by the net stress to keep the specimen shape flat.

• The Journal of Korean Physical Therapy
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• 제24권2호
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• pp.66-72
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• 2012

Purpose: The purpose of this study is to explore the importance of the image distortion correction in the cross sectional area measurement for the iliopsas muscle, tensor fasciae latae muscle, gluteus maximus muscle and the knee extensor muscles, by using (magnetic resonance imaging) MRI. Methods: This study was performed using an open 0.32T MRI system. To estimate the image distortion, T1 images for an AAPM homogeneity/linearity phantom were acquired, and the region in which the maximum geometric distortion was less than or equal to the pixel size (1.6 mm) of the images, it was defined as the distortion correction-free region. The T2 images for a human subject's pelvis and thigh in normal positions were obtained. Then, after the regions of interest in the pelvis and thigh were moved into the distortion correction-free region, T2 images for the pelvis and thigh were scanned with the same imaging parameters used in the previous T2 imaging. The cross-sectional areas were measured in the two T2 images that were obtained in the normal position, and the distortion correction-free region, as well as the area error caused by geometric image distortion was calculated. Results: The geometrical distortion is gradually increased, from the magnet center to the outer region, in axial and coronal plane. The cross-sectional area error of gluteus maximus muscle and the knee extensors was as high as 9.27% and 3.16% in before and after distortion correction, respectively. Conclusion: The cross-sectional area of the muscles that suffered from the geometrical distortion is necessary to correct for the estimation of the intervention.

• 한국정밀공학회지
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• 제33권2호
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• pp.121-128
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• 2016

The mechanical jointing method is very important in the machine parts and structure. They are used by the bolts and rivet because it is very convenient to replace the parts and the structure. However, the mechanical jointing methods using the bolt and rivet needed the open hole. The machine parts life cycle is reduced because this open hole created the stress concentration. Therefore, the measurement methods are needed to evaluate phenomenon of the stress concentration. This paper discusses the development of the measurement algorithm using the digital image correlation methods to measure the strain distribution of the open hole. To implement the measurement algorithm using the DIC, the LabVIEW 2010 programming tool was used. To measure the strain distribution of the open hole, the tensile specimens having an open hole are made by using the aluminum 6061-T6. To secure the reliability of measurement result using the DIC, the DIC measurement results and FEM analysis results were compared.