• Journal of Biomedical Engineering Research
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• v.25 no.6
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• pp.605-609
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• 2004

Blood pressure (BP) is one of the important physiological parameters for diagnosing cardiovascula diseases by means of noninvasive method. Existing noninvasive methods for measuring arterial BP have to use cuff and difficult in measuring arterial BP continuously. Systolic blood pressure (SBP) and pulse transit time (PTT) have a kind of inverse relationship. We acquired PTT data when subjects were in relaxation and also after exercise. We performed the linear regression analysis for making the regression equations for each subject and the regression equation for all subjects. We compared the estimated SBP with the measured SBP to check the accuracy of our regression equations. From the result, the regression equations for each subject was appropriate according to the American National Standards Institute of the Association of the Advancement of Medical Instrument (ANSI/AAMI) which says that BP devices should have ±5mmHg mean of error and 8mmHg standard deviation of error. However, the regression equation for all subjects was not proper to ANSI/AAMI recommendation. The result means that, without cuff, we can continuously estimate each subject's SBP through PTT and indivisual calibration.

• Journal of Korean Tunnelling and Underground Space Association
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• v.21 no.3
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• pp.347-362
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• 2019

Underground excavation using TBM machines has been increasing to reduce complaints caused by noise, vibration, and traffic congestion resulted from the urban underground construction in Korea. However, TBM excavation design and construction still need improvement because those are based on standards of the technologically advanced countries (e.g., Japan, Germany) that do not consider geological environment in Korea at all. Above all, although TBM performance is a main factor determining the TBM machine type, duration and cost of the construction, it is estimated by only using UCS (uniaxial compressive strength) as the ground parameters and it often does not match the actual field conditions. This study was carried out as part of efforts to predict penetration rate suitable for Korean ground conditions. The effective parameters were defined through the correlation analysis between the penetration rate and the geotechnical parameters or TBM performance parameters. The effective parameters were then used as variables of the multiple regression analysis to derive a regression model for predicting TBM penetration rate. As a result, the regression model was estimated by UCS and joint spacing and showed a good agreement with field penetration rate measured during TBM excavation. However, when this model was applied to another site in Korea, the prediction accuracy was slightly reduced. Therefore, in order to overcome the limitation of the regression model, further studies are required to obtain a generalized prediction model which is not restricted by the field conditions.

• Journal of Advanced Navigation Technology
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• v.16 no.6
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• pp.1116-1122
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• 2012

Many researches predicted the linear relationship between discretionary expenditure and sales amount in manufacturing companies. We review their relationship based on financial reports of KOSDAQ and KOSPI listed companies in category of non-durable goods. Also we review the relationship between expenditure on intangible capital and sales amount in aviation service and related manufacturing firms. Identified manufacturing firms showed linear relationship between R&D expenditure and sales amount. On the contrary, aviation service and related manufacturing companies do not have linear relationship between expenditure on intangible capital and sales, while their general management and sales expenditure has linear relationship with sales. It shows aviation service and related manufacturing company keep advertising or R&D related expenditure as sales revenue decreases, while manufacturing companies of non-durable goods has a tendency to reduce it as sales revenue decreases.

• Journal of the Earthquake Engineering Society of Korea
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• v.14 no.4
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• pp.23-28
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• 2010

This study evaluated the effect of vibration, level of lateral yielding strength, site conditions, ductility factor, strain-hardening ratio, and post-capping ratio of the strength limited bilinear SDF systems on the inelastic displacement ratio. The nonlinear response history analysis was conducted using 240 ground motions which were collected at the sites classified as site classes B, C, and D according to the NEHRP. To account for the P-$\Delta$ effects, this study considered negative stiffness ratios ranging from -0.1 to -0.5 of elastic stiffness. Four different damping ratios are used: 2, 5, 10, and 20%. From this study, an equation of inelastic displacement ratio was proposed using nonlinear regression analysis.

• The Journal of the Convergence on Culture Technology
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• v.6 no.4
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• pp.655-661
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• 2020

In this study, the correlation between concrete core compressive strength and rebound hardness of urban railway underground structures was analyzed. The equations for the range of rebound hardness were derived and compared with the measured concrete core strengths for each range of rebound hardness to confirm the adequacy of the estimated compressive strength. As the result, the linear regression analysis results of the average compressive strength by the Gaussian probability density function (representative compressive strength estimation formula) and the estimation formula by the rebound hardness range were founded to match well within 3% of the experimental concrete core compressive strength test results. Therefore, the stochastic statistical analysis using the rebound hardness measurement results suggested in this study could be help to secure the confidence level of the correlation between the rebound hardness and the concrete compressive strength which are relatively large deviation according to the estimation equations.

• Fire Science and Engineering
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• v.18 no.1
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• pp.1-6
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• 2004

In the reutilization process using limonene, the organic solvent to reduce volume of EPS, the AIT was measured with the variation of concentration and volume of mixture, in order to present the fund-mental data on the fire hazard assessment of limonene - EPS mixture at storage and handling. And ignition zone was compared with non-ignition zone. The equation related to AIT, activation energy and ignition delay time, used by the most scientific basis for predicting AIT values, was suggested using linear regression analysis as ln t = 0.704/T-5.819. And the equation related to concentration of mixture and AIT was also suggested to predict ignition hazard of combustible mixture using nonlinear regression analysis as $T_m/=248.32+69.27X+172.60X^2$. It enabled to predict ignition temperature according to variation of ignition delay time and concentration of mixture by the suggested equations.

• Korean Journal of Environment and Ecology
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• v.34 no.1
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• pp.55-62
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• 2020

To estimate headwater stream temperature with seasonal variations, we analyzed precipitation, runoff and air temperature in experimental forest of Kangwon National University, Gangwon-do (2017~2018 years). The daily mean value of headwater stream temperature for spring was 6.9~17.7℃ and correlated with air temperature, that for summer and fall were 12.2~26.3℃ and 3.6~19.3℃, correlated with air temperature and runoff. Based on seasonal variations, we applied for stepwise multiple linear regression analyses to estimate headwater stream temperature with seasonal variations. The equations were headwater stream temperature(WT)_spring=(0.553×Air temperature)+(0.086×Runoff)+4.145 (R²=0.505; p<0.01), WT_summer=(0.756×Air temperature)+(-0.072×Runoff)+2.670 (R²=0.510; p<0.01), and WT_fall=(0.738×Air temperature)+(0.028×Precipitation)+2.660 (R²=0.844; p<0.01). The coefficient of determination (R²) was greater than when it was estimated by air temperature in all seasons and progressively increased from spring to winter. Therefore, we indicated difference on estimated magnitude of stepwise multiple linear regression, due to effects on headwater stream temperature of different environmental factors with seasonal variations. Furthermore, temporal factors with spatial characteristics (e.g., river versus headwater stream) could be recommended for estimating headwater stream temperature.

• Magazine of the Korea Concrete Institute
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• v.10 no.1
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• pp.119-124
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• 1998

콘크리트는 시멘트, 잔골재 및 굵은 골재, 물 및 첨가제의 양이나 투입순서 ,혼합방법등 여러 가지 요인에 따라 성질이 바뀌게 되는 복합재료이다. 따라서 넓은 의미에서 품질 판정의 한 수단이 되는 콘크리트의 설계기준강도 또는 압축강도 fc'(=28일 압축강도)는 물론 기타의 성질도 정확한 예측이 불가능하다. 즉 소요강도를 목표로 배합된 공시체의 시험결과는 예외없이 통계적 가변성을 나타낸다. 여기에서는 공시체의 7일 강도의 평균치 및 표준 편차와 공시체의 28일 강도 측정치로부터 콘크리트의 압축강도를 추정하는식을 제안하였다. 이를 위하여 7,320개의 강도시험자료를 수집한 후 이들을 선형 회귀 분석법으로 처리하였다. 제안된 식에 의한 콘크리트의 압축강도는 타 추정식에 의한 값보다 실측치에 좀 더 근접함을 보여주었다. 또한 제안식의 검정을 위해 서울지역 자료 5,200개를 수집하여 제안식과 JIS, Slater식과의 오차를 비교한 결과에 따르면 제안식이 더 안전측임을 알 수 있었다. 그리고 슈미트 햄머에 의한 현장 실측 강도와 제안식과의 콘크리트 강도 오차는 대체로 2.3%이었다.

• Proceedings of the Korea Information Processing Society Conference
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• 2016.04a
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• pp.953-955
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• 2016

본 논문은 다중 회귀 분석을 이용하여 3축 가속도센서기반의 활동량을 추정하는 방법을 제안한다. 본 연구를 위해 총 59명의 피 실험자가 자체 제작한 활동량계를 착용한 뒤 트레드밀에서 일정한 속도로 걷는/뛰는 동작을 수행한 신호를 수집하였다. 수집한 3축 가속도 신호의 에너지 값에서 사전에 정의한 특징들을 산출한다. 그 다음 각 특징별로 선형, 지수, 로지스틱 회귀 분석을 적용하여 적합도가 높은 특징을 선정한다. 마지막으로 산출된 회귀식들을 사용하여 다중 회귀 분석 방법으로 활동량을 추정한다. 호흡가스 대사 분석기(K4B2)를 착용한 뒤 동일한 방법으로 실험을 수행 하고 제안한 방법과 정확도를 비교한 결과 제안한 방법의 정확도는 86.38 %로 산출되었다. 이는 기존의 Kim 외 3인의 연구결과[1]보다 2.70 %, Actical의 정확도보다 4.31 % 높은 수치이다.

• The Journal of Engineering Geology
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• v.17 no.2 s.52
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• pp.217-224
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• 2007

Tunnel displacement happens during the process of stress redistribution by tunnelling. Tunnel displacement can be divided into 3 types such as displacements occurring before excavation, non-measured displacements after excavation and measured displacements after excavation. Because measurements of displacements occurring before excavation and non-measured displacement after excavation are difficult and time-consuming in the field, many researchers have studied on total displacement and its characteristics with excavation using numerical analysis. In this study, we used a 3-D back analysis to estimate total displacement by rock mass grades in tunnel constructed in sedimentary rock. We reduced error between measured displacements and calculated displacements from a 3-D numerical analysis, and then estimated suitable rock mass properties by RMR classes. Ultimately, Logistic nonlinear regressions of total displacement with tunnelling were estimated by least square estimation.