• Journal of Sensor Science and Technology
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• v.26 no.4
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• pp.239-244
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• 2017

Noninvasive, cuffless, and continuous blood pressure (BP) monitoring is essential to prevent and control hypertension. A well-known existing method for this measurement is pulse transit time (PTT), which has been investigated by many researchers as a promising approach. However, the fundamental principle of the PTT method is based on the time interval taken by a pulse wave to propagate between the proximal and distal arterial sites. Consequently, this method needs an independent system with two devices placed at two different sites, which is a problem. Even though some studies attempted to synchronize the system, it is bulky and inconvenient by contemporary standards. To find a more sensitive method to be used in a BP measurement device, this study used radial electrical bioimpedance (REB) as a potential indicator for BP determination. Only one impedance plethysmography channel at the wrist is performed for demonstrating a ubiquitous BP wearable device. The experiment was evaluated on eight healthy subjects with the ambulatory BP monitor on the upper arm as a reference. The results demonstrated the potential of the proposed method by the correlation of estimated systolic (SBP) and diastolic (DBP) BP against the reference at $0.84{\pm}0.05$ and $0.83{\pm}0.05$, respectively. REB also tracked the DBP well with a root-mean-squared-error of $7.5{\pm}1.35mmHg$.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1910-1911
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• 2007

A new method for estimating and eliminating electrocardiogram (ECG) artifacts from single channel scalp electroencephalogram (EEG) is proposed. The proposed method consists of emphasis of QRS complex from EEG using least squares acceleration (LSA) filter, generation of synchronized pulse with R-peak and ECG artifacts estimation and elimination using adaptive filter. The performance of the proposed method was evaluated using simulated and real EEG recordings, we found that the ECG artifacts were successfully estimated and eliminated in comparison with the conventional multi-channel techniques, which are independent component analysis (ICA) and ensemble average (EA) method. In conclusion, we can conclude that the proposed method is useful for the detecting and eliminating the ECG artifacts from single channel EEG and simple to use for ambulatory/portable EEG monitoring system.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.15 no.2
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• pp.81-86
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• 2004

Background and Objectives : In general, ambulatory 24-hour pH monitoring is considered the current gold standard for larynogopharyngeal reflux(LPR). There is no validated instrument whose purpose is to document the physical finding and severity of laryngopharyngeal reflux. The purposes of this study are to revaluate the validity and reliability of the reflux finding score(RFS) and to quantify laryngoscopic findings using reflux finding score. Material and Methods : Thirty-three LPR patients confirmed by dual-probe pH monitoring and thirty patients of control were selected. The RFS was documented for each patient with telescopic laryngoscopy before treatment. For test-retest intraobserver reliability assessment, a blinded laryngologists determined the RFS on two separate occasions. To evaluate interobserver reliability assessment, the RFS was determined by t재 different blinded laryngologists. Results : The mean age of the cohort with pH-documented LPR was 45.8 years and the mean RFS was 11.4. The mean age of cotrol subjects was 52 years and the mean RFS was 5.4. The mean RFS for laryngologist no. 1 was 10.8 at the initial screening and 10.9 at the repeat evaluation. The mean FRS for laryngologist no.2 was 11.1 at the intial test and 10.9 at the repeat evaluation. The correlation coefficient for interobserver variability was 0.93 and intraobserver variability was 0.94. Conclusion : The RFS demonstrates excellent inter-and introaobserver reproducibility and is helpful for quantifying laryngeal finding in LPR. We can be 95% certain that an individual with a RFS greater than 7 has LPR.

• Safety and Health at Work
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• v.6 no.3
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• pp.192-199
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• 2015

Background: Overweight, obesity, and cardiovascular disease risk factors are prevalent among firefighters in some developed countries. It is unclear whether physical activity and cardiopulmonary fitness reduce cardiovascular disease risk and the cardiovascular workload at work in firefighters. The present study investigated the relationship between leisure-time physical activity, cardiopulmonary fitness, cardiovascular disease risk factors, and cardiovascular workload at work in firefighters in Hong Kong. Methods: Male firefighters (n = 387) were randomly selected from serving firefighters in Hong Kong (n = 5,370) for the assessment of cardiovascular disease risk factors (obesity, hypertension, diabetes mellitus, dyslipidemia, smoking, known cardiovascular diseases). One-third (Target Group) were randomly selected for the assessment of off-duty leisure-time physical activity using the short version of the International Physical Activity Questionnaire. Maximal oxygen uptake was assessed, as well as cardiovascular workload using heart rate monitoring for each firefighter for four "normal" 24-hour working shifts and during real-situation simulated scenarios. Results: Overall, 33.9% of the firefighters had at least two cardiovascular disease risk factors. In the Target Group, firefighters who had higher leisure-time physical activity had a lower resting heart rate and a lower average working heart rate, and spent a smaller proportion of time working at a moderate-intensity cardiovascular workload. Firefighters who had moderate aerobic fitness and high leisure-time physical activity had a lower peak working heart rate during the mountain rescue scenario compared with firefighters who had low leisure-time physical activities. Conclusion: Leisure-time physical activity conferred significant benefits during job tasks of moderate cardiovascular workload in firefighters in Hong Kong.

• Journal of Preventive Medicine and Public Health
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• v.44 no.3
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• pp.131-139
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• 2011

Objectives: Masked hypertension is associated with metabolic risks and increased risk of cardiovascular disease. The purpose of this study was to identify the frequency of and risk factors of masked hypertension in Korean workers. Methods: The study was conducted among 121 employees at a hotel in Gyeongju, Korea, from December 2008 to February 2009. We measured blood pressure (BP) both in the clinic and using 24-hour ambulatory BP monitors for all subjects. Hypertension was defined independently by both methods, and subjects were classified into four groups: true normotension, masked hypertension, white coat hypertension, and sustained hypertension. Results: The frequency of masked hypertension in our study group was 25.6%. Compared with true normotension, the factors related to masked hypertension were male gender (odds ratio [OR], 10.7; 95% confidence interval [CI], 1.41 to 81.09), aging one year (OR, 0.88; 95% CI, 0.78 to 0.99), clinic BP 120-129 /80-84 mmHg (OR, 8.42; 95% CI, 1.51 to 46.82), clinic BP 130-139 / 85-89 mmHg (OR, 12.14; 95% CI, 1.80 to 81.85), smoking (OR, 5.51; 95% CI, 1.15 to 26.54), and increase of total cholesterol 1 mg / dL (OR, 1.05; 95% CI, 1.02 to 1.08). In males only, these factors were clinic BP 120-129/ 80-84 mmHg (OR, 15.07; 95% CI, 1.55 to 146.19), clinic BP 130-139/ 85-89 mmHg (OR, 17.16; 95% CI, 1.56 to 189.45), smoking (OR, 11.61; 95% CI, 1.52 to 88.62), and increase of total cholesterol 1 mg/dL (OR, 1.05; 95% CI, 1.01 to 1.09). Conclusions: The frequency of masked hypertension was high in our study sample. Detection and management of masked hypertension, a known strong predictor of cardiovascular risk, could improve prognosis for at-risk populations.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.8 no.2
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• pp.143-149
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• 2005

Purpose: The aim of this study was to evaluate the significance of pH monitoring at two levels, hypopharynx and esophagus in gastroesophageal reflux. Methods: 29 patients with pathological gastroesophageal reflux were classified into two groups: Group I had recurrent respiratory symptoms and Group II had not recurrent respiratory symptoms. The ambulatory pH monitoring was performed at the hypopharynx and the esophagus simultaneously with two channel catheter for 18~24 hr. The pathological reflux was defined when the percent of time that pH was below 4.0 exceeding the 95th percentile of normal value. Hypopharyngeal reflux was defined as the pharyngeal pH drops below 4. Results: 39 patients were performed pH monitoring at the level of hypopharynx and esophagus for 24 hours. Among 7 patients with chronic respiratory symptom, 6 patients (85.7%) have pathological esophageal reflux. Among 32 patients without chronic respiratory symptom, 23 patients (71.8%) have pathological esophageal reflux. Thus 29 out of 39 patients (74%) have pathological esophageal reflux. In the Group I, all parameters except the longest episode showed significant differences between hypopharyngeal and esophageal pH monitoring. None of parameters showed significant differences between group I and II in the pharyngeal pH monitoring. Conclusion: Regardless of presence of respiratory symptoms, the pH monitoring at the pharyngeal level in patients with gastroesophageal reflux did not showed any differences compared with the esophageal pH monitoring. Therefore we may reconsider the usefulness of hypopharyngeal pH monitoring in patients with chronic respiratory symptoms.

• Journal of the Korean Society of Clothing and Textiles
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• v.34 no.1
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• pp.112-125
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• 2010

A Holter monitor is used for ECG monitoring of ambulatory daily life in hospital. However, the use of this apparatus causes skin allergies and discomfort in patients because of the attachment gel and tapes used to attach disposable electrodes to the skin. In this study, the development of tight-fitting clothing connected to a portable Holter monitor was proposed. In addition, the use of conductive fabrics as electrodes was proposed; this will enable the use of garments in u-health care for measuring ECG signals. The male subjects were university students in the ages of 20 to 24. Subjective wear sensations of the experimental garments were rated using seven Likert scales. A Likert type scale was used for the evaluation and a 7 point score indicates that it provided the best fit as a tight-fitting upper clothing. Clothing pressure was measured using an air-pack-type pressure sensor (model AMI 3037-2) at 4 locations (the conductive fabric electrode) As results, a male basic sloper for upper clothing was developed and that pattern was manipulated to the tight fit pattern by considering the reduction rate of the percentage stretch in the fabric. The developed tight-fitting garment was superior in terms of subjective sensation and 6t. The mean pressure of the garment with reduction rates of 40% in width and of 50% in length was 8.45gf/$cm^2$. A conductive fabric electrode was developed by considering the sewing method and the developed electrode was detected well. The ECG data were recorded for 13 hr 19 min 44 sec and the artifacts in the ECG signals were recorded for 9 hr 3 min 46 sec (total time: 22 hr 23 min 23 sec). The artifacts data were obtained during heavy activities.

• Anxiety and mood
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• v.2 no.1
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• pp.28-32
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• 2006

Objectives : Non-cardiac chest pain (NCCP) can be divided into gastroesophageal reflux disease (GERD) related NCCP and non-GERD related NCCP. Our study was designed to examine the differences in clinical characteristics and psychological mood states between the two clinical syndromes. Methods : After some cardiologic evaluations such as treadmill exercise, coronary angiography, and echocardiography, 27 patients with NCCP were enrolled in this study. They were divided into patients with GERD related NCCP (12 patients) and those with non-GERD related NCCP (15 patients) using the upper gastrointestinal endoscopy and the ambulatory 24 hour esophageal pH monitoring. Clinical characteristics such as typical reflux symptoms and psychological mood states were measured. Patients who showed scores more than 10 on the Beck Depression Inventory (BDI) or Beck Anxiety Inventory (BAI) were defined as depressed or anxious group. Anxiety sensitivity Index (ASI) was also measured in all patients. All parameters were compared between patients with GERD related NCCP and those with non-GERD related NCCP. Results : The two groups showed a difference in typical reflux symptoms. Patients with non-GERD related NCCP had higher scores on the BDI, BAI and ASI than those with GERD related NCCP. Among all NCCP patients, 14 patients (51.9%) were suggested to have possible depression or anxiety disorders. Conclusion : The non-GERD related NCCP was shown to be associated with psychological mood states such as anxiety and depression. Thus, we suggest that routine measurement of psychological mood states should be necessary in the evaluation and treatment of NCCP.

• The Journal of Internal Korean Medicine
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• v.20 no.1
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• pp.222-231
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• 1999

Uwhangchungsimwon(UC) has been used in the treatment of a wide variety of conditions including stroke, hypertension, arteriosclerosis, autonomic imbalance, mental instablity, etc in Korean traditional hospitals, In particular it is often initialy chosen for emergency care of acute stroke. The aim of this study was to evaluate the effect of UC on cerebral hemodynamics. Using transcranial Doppler ultrasound, we studied changes of mean flow velocity and pulsatility index(PI) of middle cerebral arteries (MCAs) from 11 health young volunteers who were administrated with 1 pill UC and 11 health controls who were not. We obtained hypercapnia with breath-holding and evaluated cerebrovascular reactivity with breath-holding index(BHI). Systolic blood pressure, diastolic blood pressure, and heart rate were measured using ambulatory blood pressure monitoring(ABPM). In UC administration group, the evaluation was performed during basal condition. and repeated at 20, 40, and 60 min after administration. In controls, the evaluation was performed at corresponding time intervals. Mean flow velocity in middle cerebral artery, systolic blood pressure, diastolic blood pressure, and heart rate did not change during the observation period and were not different between these two groups. However, administration of UC was associated with decreases in PI by $3.6{\sim}12.4%$ in BHI by $17.9{\sim}24.8%$ compared with pre-administration period. Decreases in PI and BHI with UC were significantly different compared with control group (p<0.05). These results indicate that UC decreases PI and BHI in cerebral artery, which is due to a dilation of cerebral resistance vessels.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.3 no.1
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• pp.9-16
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• 2000

Purpose: The aim of this study was to determine how much acid exposure would occur in the proximal esophagus, both in normal and in patients with abnormal distal esophageal acid exposure. Methods: Fourty-six patients with suspected GER were classified into two groups, 24 patients with pathological distal reflux (group I); 22 patients with normal distal reflux (group II). The ambulatory dual-probe esophageal pH monitoring was performed for 18-24hr. The abnormal reflux was defined when the percent of time that pH was below 4.0 exceeded the 95th percentile of normal value. Results: The siginficant differences between distal and proximal esophageal pH recordings in group I persisted for all parameters except for the longest episode, but didn't persist in group II. At the distal esophageal site, the median percent time with pH<4.0 in group I was 19.3 and significantly higher than at proximal site. Half of patients with pathological distal reflux also had proximal acid reflux. Correlation coefficients between the distal and proximal esophageal sites in group I of the number of reflux episodes and time of the longest episode were 0.451 and 0.646 respectively. Conclusion: The 50 percent of patients with pathological distal acid reflux also had abnormal acid exposure in the proximal esophageal site. Therefore, we recommand simultaneous pH recordings from dual probe esophageal sites in children with gastroesophageal reflux.