• 대한방사선기술학회지:방사선기술과학
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• 제46권5호
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• pp.401-408
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• 2023

Thyroid uptake measurements can be subject to measurement errors due to the scoping and positioning of the thyroid gland. To compensate for these limitations, the clinical utility of the thyroid simultaneous counting method as an alternative to thyroid uptake measurement was analyzed and evaluated experimentally through quantitative analysis of images acquired after thyroid scanning. Experimental data were obtained using a Gamma camera (GE infinia), a thyroid uptake system (KOROID 1), and a thyroid neck phantom. Based on the thyroid uptake rate of 1-5% according to the protocol of thyroid scan test (^99mTcO₄ - , 370 MBq) in normal results, ^99mTcO₄ - was set in the range of 3.7-18.5 MBq (Matrix: 256×256, Scan time: 1 min, collimator: pin hole, phantom-collimator distances: 7 cm). The acquired images were corrected for the attenuation of isotopes due to the set-up time and half-life by applying the Auto Region of interest (ROI) drawing system, and the significance of the experimental results was evaluated by Multiple linear regression analysis (SPSS, ver. 22, IBM). The thyroid uptake rate showed a significant correlation between the dose and the measured counts when using the thyroid uptake system equipment. Meanwhile, the quantitative analysis counts of phantom images using Gamma camera also showed a significant correlation. Thus confirmed that the correlation between these two experiments was statistically significant (P<0.05). The simultaneous counting protocol, which indirectly measures thyroid uptake from thyroid scans, is likely to be clinically relevant if complemented by additional studies with different variables in patients with thyroid disease.

• 한국대기환경학회지
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• 제33권5호
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• pp.515-520
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• 2017

$PM_{2.5}$ concentrations were measured using a cyclone, impactor (the U.S. Environmental Protection Agency well impactor ninety-six, WINS) and optical particle counter (OPC) at a campus site located in Yongin for the period August 2014 through March 2017. The concentrations from cyclone (Y) were generally higher than those from impactor(X); the best-fit line was Y=1.22X+5.64. The ratios of $PM_{2.5}/PM_{10}$ ranged from 0.61 to 0.66 when $PM_{2.5}$ concentrations from cyclones in selected studies were converted into those from impactors using a regression equation in this study. The slope of the best-fit line between OPC and impactor was close to 1 at 0.95, while that between OPC and cyclone was 0.72. After sampling, the flow rate in the low-volume air sampler with cyclone decreased by 3% on average, which did not have a significant effect on measured concentrations.

• 한국농공학회지
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• 제38권3호
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• pp.127-136
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• 1996

The purpose of this study is to provide with information for the water resources development and management in stream management planning, such as information on the sediment trensport, design of dam and water facilities, river improvement and flood plains management. The major results obtained from the field measurement and analysis of the watershed characteristics, hydraulic and sediment characteristics are as follows ; 1. The rating curve formulas obtained from the analysis of the hydraulic characteristics data collected are ; Q-=110.563 $(H-0.474)^2$ for 0.7m$(H-0.146)^2$ for 0.4m$Sr=aX{^2} {_1} X^{c}{_2}$, in the experimental watershed.

• 한국병원경영학회지
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• 제10권1호
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• pp.71-92
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• 2005

The purpose of this study is to analyze the efficiency in management of general hospitals and investigate the major factors on efficiency. Specifically, the management of each general hospital is evaluated by using Data Envelopment Analysis(DEA) technique which is a nonparametric statistical method for measurement of efficiency. Then, the influencing factors are investigated through analyses of Decision-Tree Model and Tobit Regression. The target hospitals were general hospitals in which bed sizes are between 200 and 500 among a total of 276 general hospitals. The main data of financial indicators were collected from 48 hospitals, and it was analyzed by using two statistical models. For Model I, three input and two output variables were used for efficiency evaluation. In particular, three input variables were the number of medical doctors, the number of paramedical personnel, and the bed size. And, two output variables were the numbers of inpatients and outpatients per year, adjusted by bed-size. The results of DEA analysis showed that only seven out of 48 hospitals(15%) turned out to be efficient. The decision-tree analysis also showed that there were six significant influencing factors for Model I. Six factors for Model I were Bed Occupancy Rate, Cost per Adjusted Inpatient, New Visit Ratio of Outpatients, Retired Ratio, Net Profit to Gross Revenues, Net Profit to Total Assets. In addition, the management efficiency of hospital is proved to increase as profit and patient-induced indicators increase and cost-related indicators decrease, by the Tobit regression model of independent variables derived from the decision-tree analysis. This study may be contributable to the development of analytic methodology regarding the efficiency of hospital management in that it suggests the synthetic measures by utilizing DEA model instead of suggesting simple ratio-analyzing results.

• 기술혁신연구
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• 제23권1호
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• pp.87-105
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• 2015

본 연구는 한국 제조업 중소기업의 R&D 투자와 성과 간의 관계를 분석하여 비선형 형태를 확인하고, 문턱값인 투자적정수준을 도출하였다. 기존 연구들은 투자와 성과 간 시차를 고려하지 않거나, 투자와 성과 간 회귀모형에서 투자 변수의 1차, 2차 항을 이용한 산술적 계산을 통하여 간접적으로 투자수준을 결정하였는데, 본 연구에서는 이를 극복하기 위해 2년의 시차를 가정한 문턱회귀모형을 사용하였다. 분석결과에 의하면, R&D 집중도 및 연구원비율과 이익률간의 관계는 S곡선 형태를 보였고, 매출액 대비 R&D 투자액 기준으로 6.4%, 종업원수 대비 연구원수 기준으로 13%가 R&D 투자의 적정수준으로 도출되었다. 연구로부터 도출된 투자 및 성과 간 관계 형태와 문턱값은 향후 기업의 R&D 투자 전략 및 정부 지원 정책의 기초자료로 활용될 수 있을 것으로 기대된다.

• 지구물리와물리탐사
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• 제17권3호
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• pp.121-128
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• 2014

투과도는 다공질 암석 내에서 유체의 유동 특성을 나타내는 중요한 매개변수로서 일반적으로 코어 시료의 유체 유동실험을 통해 산출된다. 하지만, 유체 유동실험을 위해서는 별도의 실험장치가 필요하며, 투과도가 낮을 경우 많은 시간이 소요될 수 있다. 본 연구에서는 일련의 투과도 측정 실험 없이 시료의 건조과정만으로 투과도를 도출하기 위해 유체투과도, 공극률, 건조율간의 상관관게를 분석하였다. 공극률은 표면건조 포화시료를 건조시키면서 무게 변화를 연속적으로 측정하는 건조 모니터링 방법을 이용하여 산출하였으며, 건조율은 물 포화율에 따른 시료의 무게 변화율로부터 구했다. 70 ~ 670 mD의 투과도를 보이는 6개의 베레아 사암을 이용해 회귀분석한 결과 공극률 및 건조율로부터 다공성 사암의 투과도를 예측할 수 있는 새로운 경험식을 도출하였다.

• 한국산업보건학회지
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• 제32권1호
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• pp.21-30
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• 2022

Objectives: The purpose of this study is to suggest an optimal method by comparing the analysis methods of work environment measurement datasets including left-censored data where one or more measurements are below the limit of detection (LOD). Methods: A computer program was used to generate left-censored datasets for various combinations of censoring rate (1% to 90%) and sample size (30 to 300). For the analysis of the censored data, the simple substitution method (LOD/2), β-substitution method, maximum likelihood estimation (MLE) method, Bayesian method, and regression on order statistics (ROS)were all compared. Each method was used to estimate four parameters of the log-normal distribution: (1) geometric mean (GM), (2) geometric standard deviation (GSD), (3) 95th percentile (X95), and (4) arithmetic mean (AM) for the censored dataset. The performance of each method was evaluated using relative bias and relative root mean squared error (rMSE). Results: In the case of the largest sample size (n=300), when the censoring rate was less than 40%, the relative bias and rMSE were small for all five methods. When the censoring rate was large (70%, 90%), the simple substitution method was inappropriate because the relative bias was the largest, regardless of the sample size. When the sample size was small and the censoring rate was large, the Bayesian method, the β-substitution method, and the MLE method showed the smallest relative bias. Conclusions: The accuracy and precision of all methods tended to increase as the sample size was larger and the censoring rate was smaller. The simple substitution method was inappropriate when the censoring rate was high, and the β-substitution method, MLE method, and Bayesian method can be widely applied.

• 대한의용생체공학회:의공학회지
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• 제31권5호
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• pp.375-384
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• 2010

The purpose of this study is to determine whether there is a correlation between the segmental bio-impedance measurement with the frequency modulations and the life-style disease of obesity. An obesity is not simply the factor for estimating the life-style disease of obesity, but also the risk factor occurring. There are many methods (BMI, WHR, Waist, CT, DEXA, BIA, etc.) for measuring a degree of obesity; the bio-impedance measurement is more economic and more effective than others. The physical examination, the blood test, the medical imaging diagnosis and the bio-impedancemeasurementswithmultiple frequencies for each body parts have been conducted for 77 people. The estimated value has been calculated through a segmental bio-impedance model based on multi-frequency that was created to reflect the highest correlation by analyzing correlation with linear regression analysis method for the measured bio-impedance and the risk factors. Then we compared with the clinical diagnosis. In case of high level cholesterol, low HDL-C and high LDL-C for life-style disease, the sensitivity is 80~100%and the specificity is 83~100%. This study has shown conclusively that bio-impedance can be a possible predictor to analyze the disease risk rate of population and individual health maintenance. And also the multi-frequency segmental bio-impedance can be used as early predictor to estimate the life-style disease of obesity.

• 보존과학회지
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• 제34권6호
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• pp.503-515
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• 2018

원주 법천사지 지광국사탑의 1957년 수리 복원에 사용된 모르타르의 손상정도를 평가하고 제거 필요성에 대한 객관적인 데이터를 제공하기 위해 콘크리트 분야에서 사용되는 반전위측정방법을 적용하였다. 철근이 사용된 옥개석 모르타르와 실내 실험체의 촉진부식시험 후 반전위 측정값에 대한 다중회귀분석 결과, 부식량과 피복두께에 따른 HCP 값의 결정계수는 0.86이상의 높은 상관식이 도출되었다. ASTM C876기준에 따르면 옥개석의 습윤상태 측정값 - 431~-663 mV는 철근의 부식손상 확률이 90%이상이기 때문에 손상된 모르타르를 제거한 후 신석재를 사용한 복원이 필요한 것으로 판단된다.

• 한국산학기술학회논문지
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• 제10권11호
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• pp.3458-3464
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• 2009

본 연구는 40~50대 중년 남녀를 대상으로 신체계측을 통해 얻어진 신체계측치 및 혈관탄성도와 최대산소섭 취량의 관련성을 규명하기 위하여 일개 군 보건소 운동처방실을 방문한 남자 43명, 여자 53명을 대상으로 신체계측치 및 혈관탄성도, 최대산소섭취량 등을 측정하였다. 결과를 보면 1.남자의 신체계측치와 혈관탄성도의 상관관계에서는 비만도가, 여자에서는 허리-엉덩이비율이 유의한 상관관계를 보였다. 2.남자의 신체계측치와 최대산소섭취량의 상관관계에서는 비만도, 체질량지수, 허리-엉덩이비율, 체지방율이 유의한 상관관계를 보였으며, 여자에서는 허리-엉덩이 비율, 체지방율이 유의한 상관 관계를 보였다. 3.남자의 혈관탄성도 및 심혈관계지표와 최대산소섭취량의 상관관계에서는 최대심박수가 유의한 상관관계를 보였고, 여자에서는 혈관탄성도, 최대심박수가 유의한 상관관계를 보였다. 4.최대 산소섭취량을 종속변수로 한 다중회귀분석에서는 남녀 모두 체지방율, 혈관탄성도, 최대심박수가 유의한 변수로 나타났다. 즉 체지방율이 낮을수록, 혈관탄성도가 높을수록, 최대심박수가 높을수록 최대산소섭취량이 높았다. 따라서 40~50대 중년의 최대산소섭취량에 영향을 주는 요인에는 신체계측에 의한 비만관련지수, 혈관탄성도, 심혈관계지표등 여러 요인들이 복합적으로 관련되는 것으로 판단되어진다.