Jun Su Kim

Differential association of adiposity measures with heart rate variability measures in Koreans.

Purpose Although obesity has been associated with imbalances in cardiac autonomic nervous system, it is unclear whether there are differential relationships between adiposity measures and heart rate variability (HRV) measures. We aimed to examine differences in the relationship between adiposity measures and HRV indices in a healthy Korean population. Materials and Methods In all, 1409 non-smokers (811 males, 598 females) without known histories of cardiovascular (CV), endocrine, or neurological diseases underwent adiposity measurements [(body mass index (BMI), percentage of body fat mass (PBF), and waist-to-hip ratio (WHR)], the HRV assessment (SDNN, RMSSD, LF, HF, LF/HF, and pNN50), and examination for CV risk factors (fasting glucose, LDL-cholesterol, HDL-cholesterol, triglycerides, hs-CRP, and blood pressure). Results Compared with BMI and PBF, WHR was more strongly correlated with each HRV index and more likely to predict decreased HRV (<15 percentile vs. ≥15 percentile of each HRV index) in ROC curves analysis. In linear regression analysis, all adiposity measures were inversely associated with each HRV measure before adjusting for age, gender, and CV risk factors (p<0.05). After adjusting for the covariates, WHR was inversely related to RMSSD, LF, and pNN50; PBF with RMSSD, HF, and pNN50; BMI with RMSSD (p<0.05). The inversed association between HRV indices and the gender-specific WHR tertile was significant for subjects with BMI ≥25 kg/m2, but not for those with BMI <25 kg/m2. Conclusion WHR and PBF appear to be better indicators for low HRV than BMI, and the association between abdominal adiposity and HRV may be stronger in overweight subjects.

Factors Associated with Depressive Symptom in Chronic Obstructive Pulmonary Disease Based on the Third (2005) and Fourth (2008) Korea National Health and Nutritional Examination Survey (KNHANES III, IV)

Background Depressive symptoms accompanied by chronic obstructive pulmonary disease (COPD) can be influenced by socioeconomic status, associated chronic diseases and the current smoking status. This study was conducted to assess factors that are associated with depressive symptoms accompanied by COPD, using the data obtained from the Korea National Health and Nutritional Survey (KNHANES) conducted in 2005 and 2008. Methods From the third (2005) and the fourth (2008) KNHANES, 407 (0.9%) with physician-diagnosed COPD were selected. Of the 407 subjects, only 180 (0.4%) who reported having depressive symptoms were included in this study. The associations of depressive symptoms with socioeconomic status, associated chronic diseases and smoking status were investigated. Results Of the total 180 subjects, 45 (25%) had depressive symptoms. There were 102 males (55%) and 78 females (45%) with a slight predilection for males. In multivariate analysis, significant predictors of depressive symptoms were dependent activities of daily living (odds ratio [OR], 2.42; 95% confidence interval [CI], 2.06 to 2.84) and association with number of chronic diseases (OR of one, two, and three, 1.40, 1.72, 2.60; 95% CI of one, two, and three, 1.20 to 1.63,1.41 to 2.10,1.99 to 3.39). Conclusion This study provides the basis for managing COPD patients in a clinical setting by understanding the number and characteristics of COPD patients with depressive symptoms. The results of this study suggest that primary physicians should manage COPD patients with consideration of risk factors for depressive symptom.

Evaluation of microstructure on SiCp/AZ91 magnesium composite fabricated by rotation-cylinder method

Eco-friendly development and on-going research strategy of Rotation-Cylinder Method (RCM) is given for SiCp/AZ91 Mg composites, identifying some of the key factors that need to be controlled and indicating subsequent casting processes. RCM produces U-shaped laminar melt surface with a Rankine vortex even at high rotation speed in an ambient atmosphere, which allows quick and efficient incorporation and homogeneous distribution of SiC particulates into molten Mg alloys. Therefore, sound SiCp/AZ91 Mg composites can be manufactured in conjunction with subsequent casting processes, such as investment casting and thixocasting. A transmission electron microscopy study showed that the interfacial reaction products consist of Mg2Si, MgO, Mg17Al12 and Al6Mn, which were analyzed using primitive cell volume and zero order Laue zone pattern and single convergent beam electron diffraction pattern containing higher order Laue zone ring from a nanosized region.

Software architecture and stress tracker utilising nanofibre technique-based smart clothes

Smart clothes containing nanoweb-based biosensors to acquire vital signs, known as wellness wear, have great potentiality as a wearable computing device that helps care for and promote health. This paper firstly presents a wellness wear system that we are currently developing, primarily discussing two crucial technologies of biosensors and digital yarns transmitting data, which play an important role to support comfort and wearability. Secondly, it also presents both software architecture, essential as a fundamental basis to provide sustainable and seamless various medical services, and a software application involving a stress tracker working together with the wellness wear system. The stress tracker as an example of healthcare devices, running on an Android-based smart phone, analyses the electrocardiograph (ECG) data obtained from wellness wear and provides a programme to evaluate users’ autonomous nervous system (ANS) which controls mental stress, and to give them proper biofeedback.