• Annals of Occupational and Environmental Medicine
• /
• v.35
• /
• pp.24.1-24.15
• /
• 2023

Background: The construction workers are vulnerable to fatigue due to high physical workload. This study aimed to investigate the relationship between overwork and heart rate in construction workers and propose a scheme to prevent overwork in advance. Methods: We measured the heart rates of construction workers at a construction site of a residential and commercial complex in Seoul from August to October 2021 and develop an index that monitors overwork in real-time. A total of 66 Korean workers participated in the study, wearing real-time heart rate monitoring equipment. The relative heart rate (RHR) was calculated using the minimum and maximum heart rates, and the maximum acceptable working time (MAWT) was estimated using RHR to calculate the workload. The overwork index (OI) was defined as the cumulative workload evaluated with the MAWT. An appropriate scenario line (PSL) was set as an index that can be compared to the OI to evaluate the degree of overwork in real-time. The excess overwork index (EOI) was evaluated in real-time during work performance using the difference between the OI and the PSL. The EOI value was used to perform receiver operating characteristic (ROC) curve analysis to find the optimal cut-off value for classification of overwork state. Results: Of the 60 participants analyzed, 28 (46.7%) were classified as the overwork group based on their RHR. ROC curve analysis showed that the EOI was a good predictor of overwork, with an area under the curve of 0.824. The optimal cut-off values ranged from 21.8% to 24.0% depending on the method used to determine the cut-off point. Conclusion: The EOI showed promising results as a predictive tool to assess overwork in real-time using heart rate monitoring and calculation through MAWT. Further research is needed to assess physical workload accurately and determine cut-off values across industries.

• Pediatric Gastroenterology, Hepatology & Nutrition
• /
• v.13 no.2
• /
• pp.180-192
• /
• 2010

Purpose: To evaluate the feasibility and usefulness of the waist circumference-to-height ratio (WHTR) in screening for obesity in Korean children and adolescents. Methods: Data, including body mass index (BMI), waist circumference (WC), and height, were obtained from the national growth surveys for children and adolescents in 2005. The WHTR was calculated dividing WC by height in subjects 2~18 years of age. Overweight and obese were defined by BMI percentiles for age and gender. The receiver operating characteristic (ROC) analysis was performed to find out the optimal cutoff values of WHTR that matched BMI-determined overweight and obesity using the STATA program. The area under the curve (AUC), a measure of diagnostic power, of WHTR was compared to WC. The influence of age on WHTR was analyzed by the SAS program. Results: The WHTR significantly decreased with age, and had less correlation with age in the 6~18-year-old age group than the 2~5-year-old age group. Furthermore, the WHTR also had less correlation with age than WC in the 6~18-year-old age group. The AUC of WHTR in identifying overweight and obesity was significantly higher than the AUC of WC in the 6~18-year-old age group. The optimal cutoff values were 0.51 in boys and 0.49 in girls for obesity, and 0.48 in boys and 0.47 in girls for overweight, with all having the AUC>0.9. The optimal cutoff values of WHTR had a higher sensitivity for diagnosing obesity than WC${\geq}$90th percentiles. Conclusion: The WHTR is an easy, accurate, and less age-dependent index with high applicability in screening for obesity in children and adolescents.

• Journal of the Korean Society of Radiology
• /
• v.82 no.2
• /
• pp.406-416
• /
• 2021

Purpose To evaluate the association between magnetic resonance imaging (MRI)-based texture parameters and Kirsten rat sarcoma viral oncogene homolog (KRAS) mutation in patients with non-mucinous rectal cancer. Materials and Methods Seventy-nine patients who had pathologically confirmed rectal non-mucinous adenocarcinoma with or without KRAS-mutation and had undergone rectal MRI were divided into a training (n = 46) and validation dataset (n = 33). A texture analysis was performed on the axial T2-weighted images. The association was statistically analyzed using the Mann-Whitney U test. To extract an optimal cut-off value for the prediction of KRAS mutation, a receiver operating characteristic curve analysis was performed. The cut-off value was verified using the validation dataset. Results In the training dataset, skewness in the mutant group (n = 22) was significantly higher than in the wild-type group (n = 24) (0.221 ± 0.283; -0.006 ± 0.178, respectively, p = 0.003). The area under the curve of the skewness was 0.757 (95% confidence interval, 0.606 to 0.872) with a maximum accuracy of 71%, a sensitivity of 64%, and a specificity of 78%. None of the other texture parameters were associated with KRAS mutation (p > 0.05). When a cut-off value of 0.078 was applied to the validation dataset, this had an accuracy of 76%, a sensitivity of 86%, and a specificity of 68%. Conclusion Skewness was associated with KRAS mutation in patients with non-mucinous rectal cancer.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.32 no.9C
• /
• pp.895-904
• /
• 2007

This paper proposes a robust sub-optimal smart antenna in Code Division Multiple Access (CDMA) basestation. It makes use of the property of the Least Mean Square (LMS) algorithm and the Conjugate Gradient Method (CGM) algorithm for beamforming processes. The weight update takes place at symbol level which follows the PN correlators of receiver module under the assumption that the post correlation desired signal power is far larger than the power of each of the interfering signals. The proposed algorithm is simple and has as low computational load as five times of the number of antenna elements(O(5N)) as a whole per each snapshot. The output Signal to Interference plus Noise Ratio (SINR) of the proposed smart antenna system when the weight vector reaches the steady state has been examined. It has been observed in computer simulations that proposed beamforming algorithm improves the SINR significantly compared to the single antenna case. The convergence property of the weight vector has also been investigated to show that the proposed hybrid algorithm performs better than CGM and LMS during the initial stage of the weight update iteration. The Bit Error Rate (BER) characteristics of the proposed array has also been shown as the processor input Signal to Noise Ratio (SNR) varies.

• Asian Pacific Journal of Cancer Prevention
• /
• v.16 no.16
• /
• pp.7211-7217
• /
• 2015

Background: The aims of this study were to evaluate the diagnostic and prognostic roles of serum osteopontin (OPN) and single nucleotide polymorphisms (SNPs) in the OPN promoter in patients with hepatitis B-related hepatocellular carcinoma (HCC). Materials and Methods: Four groups were studied, which included 157 patients with HCC, 73 with liver cirrhosis (LC) and 97 with chronic hepatitis (CH), along with 80 healthy subjects. Serum OPN and alpha-fetoprotein (AFP) levels were measured. The SNPs -66 T/G, -156 G/${\Delta}G$ and -433 C/T within the OPN promoter were determined by direct sequencing. Results: Serum OPN levels were significantly higher in patients with HCC than in the other groups. Area under receiver operating characteristics curves in distinguishing HCC from chronic liver disease (CLD; CH and LC) were 0.782 (95% CI; 0.729-0.834) for OPN and 0.888 (95% CI; 0.850-0.927) for AFP. Using the optimal cut-off value (70 ng/mL), OPN had sensitivity and specificity of 72% and 71%, respectively. Serum OPN was superior to AFP in detecting early-stage HCC (68% vs. 46%). A combination of both markers yielded an improved sensitivity for detecting early HCC to 82%. A high OPN level was significantly correlated with advanced BCLC stage and was an independent prognostic factor for HCC. The SNPs -156 and -443 were associated with susceptibility to HCC, but were not related to overall survival. Conclusions: Serum OPN is a useful diagnostic and prognostic marker for HCC. The combined use of serum OPN and AFP improved the diagnosis of early HCC. Genetic variation in the OPN promoter is associated with the risk, but not the prognosis of HCC.

• Asian Pacific Journal of Cancer Prevention
• /
• v.15 no.11
• /
• pp.4629-4635
• /
• 2014

Background: Diffusion-weighted imaging (DWI) makes it possible to detect malignant tumors based on the diffusion of water molecules. However, it is uncertain whether DWI has advantages over FDG-PET for distinguishing malignant from benign pulmonary nodules and masses. Materials and Methods: One hundred-forty-three lung cancers, 17 metastatic lung tumors, and 29 benign pulmonary nodules and masses were assessed in this study. DWI and FDG-PET were performed. Results: The apparent diffusion coefficient (ADC) value ($1.27{\pm}0.35{\times}10^{-3}mm^2/sec$) of malignant pulmonary nodules and masses was significantly lower than that ($1.66{\pm}0.58{\times}10^{-3}mm^2/sec$) of benign pulmonary nodules and masses. The maximum standardized uptake value (SUVmax: $7.47{\pm}6.10$) of malignant pulmonary nodules and masses were also significantly higher than that ($3.89{\pm}4.04$) of benign nodules and masses. By using optimal cutoff values for ADC ($1.44{\times}10^{-3}mm^2/sec$) and for SUVmax (3.43), which were determined with receiver operating characteristics curves (ROC curves), the sensitivity (80.0%) of DWI was significantly higher than that (70.0%) of FDG-PET. The specificity (65.5%) of DWI was equal to that (65.5%) of FDG-PET. The accuracy (77.8%) of DWI was not significantly higher than that (69.3%) of FDG-PET for pulmonary nodules and masses. As the percentage of bronchioloalveolar carcinoma (BAC) component in adenocarcinoma increased, the sensitivity of FDG-PET decreased. DWI could not help in the diagnosis of mucinous adenocarcinomas as malignant, and FDG-PET could help in the correct diagnosis of 5 out of 6 mucinous adenocarcinomas as malignant. Conclusions: DWI has higher potential than PET in assessing pulmonary nodules and masses. Both diagnostic approaches have their specific strengths and weaknesses which are determined by the underlying pathology of pulmonary nodules and masses.

• Korean Journal of Clinical Pharmacy
• /
• v.20 no.2
• /
• pp.107-113
• /
• 2010

서 론: 중환자실에서 집중적 인슐린 요법에 의한 평균혈당강하는 사망률을 감소시키는 것으로 나타났으나 이로 인한 저혈당 및 혈당변동은 새로운 문제로 대두되고 있다. 본 연구에서는 혈당과 관련한 여러 요인들이 사망에 미치는 영향을 규명하고 적정 혈당치를 확인하고자 하였다. 연구방법: 2008년 2월부터 7월 사이인 6개월 동안 서울아산병원 외과계 중환자실에서 4일 이상 재실한 18세 이상의 성인 환자를 대상으로 전자 의무기록 조사를 통해 후향적으로 연구가 진행되었다. 연구를 위해 환자의 인구학적 특성, 수술의 종류, 중환자실에서의 재실기간, 사망여부, 스테로이드 사용 유무, 기계적 인공호흡기의 사용유무, 신대체요법의 사용유무, 혈당치, 재실기간 중 스테로이드 사용유무와 인슐린 양, 입원 후 첫 24시간 동안의 포도당 주입속도, 입원 후 2일 이내와 그 이후에 발생한 균혈증 감염, APACH II와 SOFA 점수를 조사하였다. 혈당수치는 각각의 환자에서 중환자실 입실 후 가장 처음 측정된 혈당, 재실기간 중 가장 높은 혈당과 가장 낮은 혈당수치를 조사하였고 중환자실 전체 재실기간 동안 혈당수치의 평균과 변동계수를 계산하였다. 이상의 혈당관련지표를 포함한 인자들이 일차 종속변수인 사망에 어떠한 영향을 주는지를 환자를 생존군과 사망군으로 나누어 분석하였고 ROC (receiver operator characteristic) 곡선을 사용하여 혈당지표와 APACH 및 SOFA 점수의 cut-off치를 구하여 이로부터 단변량 및 다변량 분석을 시행하였다. 결 과: 연구에 포함된 환자는 170명 이었고 그 중 23명이 연구 기간 중 중환자실에서 사망하였다. 생존자에 비해 사망자의 최대혈당은 유의적으로 높았고 최소혈당치는 유의적으로 낮아 높은 변동계수를 보였다. ROC곡선으로부터 산출된 혈당치들의 cut-off 수치는 최소혈당치 70 mg/dL, 변동계수 25%, 최대혈당치 250 mg/dL, 평균혈당치 150 mg/dL이었다. 다변량분석에서 최소혈당이 70 mg/dL 보다 큰 경우가 낮은 경우에 비해 오즈비가 0.922(95% 신뢰구간 0.881-0.965)로 유의성 있게 낮았으며 변동계수가 25% 보다 높은 집단의 경우 그보다 낮은 집단에 비해 오즈비가 1.121(95% 신뢰구간 1.017-1.236)로 유의성 있게 높았다. Kaplan-Meier 생존분석 결과 최소혈당치 70 mg/dL와 변동계수 25%에 따라 생존기간에 유의성 있는 차이가 나타났다.(각각 P < 0.001, P < 0.05) 결 론: 고혈당 발생의 감소뿐 아니라 최소혈당치를 70 mg/dL 이상으로 유지하면서 변동을 최소화하는 것이 외과계 중환자실에서의 사망률감소를 위한 중요한 요인임을 알 수 있었다.

• The Journal of the Korea Contents Association
• /
• v.13 no.12
• /
• pp.829-839
• /
• 2013

This study is a descriptive research study with the purpose of predicting and comparing factors of depression affecting residents in a metropolitan city by using logistic regression analysis and decision-making tree analysis. The subjects for the study were 462 residents ($20{\leq}aged{\angle}65$) in a metropolitan city. This study collected data between October 7, 2011 and October 21, 2011 and analyzed them with frequency analysis, percentage, the mean and standard deviation, ${\chi}^2$-test, t-test, logistic regression analysis, roc curve, and a decision-making tree by using SPSS 18.0 program. The common predicting variables of depression in community residents were social dysfunction, perceived physical symptom, and family support. The specialty and sensitivity of logistic regression explained 93.8% and 42.5%. The receiver operating characteristic (roc) curve was used to determine an optimal model. The AUC (area under the curve) was .84. Roc curve was found to be statistically significant (p=<.001). The specialty and sensitivity of decision-making tree analysis were 98.3% and 20.8% respectively. As for the whole classification accuracy, the logistic regression explained 82.0% and the decision making tree analysis explained 80.5%. From the results of this study, it is believed that the sensitivity, the classification accuracy, and the logistics regression analysis as shown in a higher degree may be useful materials to establish a depression prediction model for the community residents.

• Journal of Yeungnam Medical Science
• /
• v.33 no.1
• /
• pp.8-12
• /
• 2016

Background: The decision to administer oral anticoagulation therapy depends on accurate assessment of stroke risk in patients with atrial fibrillation (AF). Various stroke risk stratification schemes have been developed to help inform clinical decision making. The CHADS2 and CHA2DS2-VASc scores have been used in estimating the risk of stroke in patients with AF. Recently R2CHA2DS2-VASc score was developed. The objective of the current study is to validate the usefulness of the R2CHA2DS2-VASc score and to compare the accuracy of the CHADS2, CHA2DS2-VASc, and R2CHA2DS2-VASc scores in predicting a patient's risk of stroke. Methods: Based on medical records, we conducted a retrospective study of patients hospitalized with AF from March 2011 to July 2013. A total of 448 AF patients were included in this study. The receiver operating characteristic (ROC) curve analysis in MedCalc was used for comparison with respective diagnostic values. Results: The patient characteristics showed male predominance (60.9%). Among the 448 AF patients, 131 (29.2%) patients had strokes during the study. A R2CHA2DS2-VASc score of more than 5 is the optimal cut-off value for prediction of stroke. A risk score of three, the area under the ROC curve (AUC) of R2CHA2DS2-VASc score (AUC 0.631; 95% confidence interval, 0.585-0.679) was the highest. A significant difference was observed between AUC for R2CHA2DS2-VASc, CHADS2, and CHA2DS2-VASc scores, but no meaningful difference between CHADS2 and CHA2DS2-VASc scores. Conclusion: We determined the usefulness of the R2CHA2DS2-VASc score, which showed better association with stroke than the CHADS2 and CHA2DS2-VASc scores.

• Tuberculosis and Respiratory Diseases
• /
• v.70 no.6
• /
• pp.498-503
• /
• 2011

Background: The causes of exertional desaturation in patients with COPD can be multifactorial. We aimed to investigate factors predict exertional desaturation in patients with moderate to severe COPD. Methods: We tested 51 consecutive patients with stable COPD (FEV1/FVC, $40{\pm}13%$ predicted). Patients performed a six minute walk test (6MWT). Pulse oxymetric saturation (SpO2) and pulse rate were recorded. Results: Oxygen desaturation was found in 15 subjects after 6MWT, while 36 subjects were not desaturated. Lung diffusing capacity was significantly lower in desaturation (DS) group ($62{\pm}18%$ predicted) compared with not desaturated (ND) group ($84{\pm}20$, p<0.01). However there was no statistical difference of FEV1/FVC ratio or residual volume between two groups. The pulse rate change was significantly higher in the desaturated compared with the not desaturated group. Six minute walking distance, subjective dyspnea scale, airflow obstruction, and residual volume did not predict exertional oxygen desaturation. Independent factors assessed by multiple logistic regression revealed that a pulse rate increment (odd ratio [OR], 1.19; 95% confidence interval [CI], 1.01~1.40; p=0.02), a decrease in baseline PaO2 (OR, 1.105; 95% CI, 1.003~1.218; p=0.04) and a decrease in lung diffusing capacity (OR, 1.10; 95% CI, 1.01~1.19; p=0.01) were significantly associated with oxygen desaturation. Receiver operator characteristic (ROC) analysis showed that an absolute increment in pulse rate of 16/min gave optimal discrimination between desaturated and not desaturated patients after 6MWT. Conclusion: Pulse rate increment and diffusion capacity can predict exertional oxygen desaturation in stable COPD patients with moderate to severe airflow obstruction.