• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.11
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• pp.2105-2110
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• 2008

Embedding the compact wearable units to monitor the health status of a person has been analysed as a convenient solution for the home health care. This paper presents a method to detect fall from the other activities of daily living and also to classify those activities. This kind of ambulatory monitoring of the elderly and people with limited mobility can not only provide their general health status but also alarms whenever an emergency such as fall or gait has been occurred and a help is needed. A timely assistance in such a situation can reduce the loss of life. This work shows a detailed analysis of the data received from a chest worn sensor unit embedding a 3-axis accelerometer and depicts which features are important for the classification of human activities. How to arrange and reduce the features to a new feature set so that it can be classified using a simple classifier and also improving the classification resolution. Principal component analysis (PCA) has been used for modifying the feature set and afterwards for reducing the size of the same. Finally a Neural network classifier has been used to analyse the classification accuracies. The accuracy for detection of fall events was found to be 86%. The overall accuracy for the classification of Activities or daily living (ADL) and fall was around 94%.

• Journal of Korean Society of Forest Science
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• v.104 no.1
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• pp.140-149
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• 2015

The aim of this study was to clarify the physiological and psychological effects of walking around and viewing a lake in a forest environment. The subjects included 11 male Japanese university students (age: $22.0{\pm}1.2$ years) who were randomly assigned to visit either a forest or an urban (control) setting. They were instructed to walk a predetermined 15-min course and to view the setting from a seated position for 15 min. Heart rate variability, heart rate, blood pressure, pulse rate, and salivary cortisol levels were measured to assess the subject's physiological responses to the environment. Four questionnaires (SD method, reports of "refreshed" feeling, POMS, and STAI) were administered to assess the subjects' psychological responses. It was found that walking around and viewing a lake in a forest environment can suppress sympathetic nerve activity, increase parasympathetic nerve activity, and decrease the heart rate, blood pressure, pulse rate, and cortisol levels. In addition, a forest environment can enhance the "comfortable," "soothing," "natural," and "refreshed" feelings, improve the mood state, and reduce anxiety. These results provide scientific evidence of the physiological and psychological effects of forest therapy.

• Journal of the Korean Magnetics Society
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• v.27 no.3
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• pp.92-97
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• 2017

It is widely known that pulsed magnetic field (PMF) is very useful tool to manipulate chemical and physiological processes in human body. The purpose of our study is to observe dynamics of rouleaux patterns of red blood cells (RBC) under PMF. The aggregation of RBCs or rouleaux formation is caused by fibrinogen in blood plasma. The maximum magnetic field intensity is 0.27 T and pulse time of 0.102 msec and pulse repetition rate was 1 Hz. PMF stimulus was applied to the palm of left hand for 5, 10, 15 and 20 min. Live blood analysis was used in vitro in order to quantitatively estimate the velocity of RBC exposed to PMF stimulus. The velocity of stacked-RBC of 10 minute PMF stimulus was increased up to $8{\times}10^{-4}m/sec$, but it decreased rapidly as the time passed. The results of present study have adduced that PMF stimulus on hand provide the improvement of RBC rouleaux formation, increase of RBC's moving velocity as well as low blood viscosity.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.2
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• pp.16-27
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• 2017

IEEE 802.15.6 standard, a Wireless Body Area Network, aims to transfer not only medical data but also non-medical data, such as physical activity, streaming, multimedia game, living information, and entertainment. Services which transfer those data have very various data rates, intervals and frequencies of continuous access to a medium. Therefore, an efficient anti-collision operations and medium assigning operation have to be carried out when multiple nodes with different data rates are accessing shared medium. IEEE 802.15.6 standard for CSMA/CA medium access control method distributes access to the shared medium, transmits a control packet to avoid collision and checks status of the channel. This method is energy inefficient and causes overhead. These disadvantages conflict with the low power, low cost calculation requirement of wireless body area network, shall minimize such overhead for efficient wireless body area network operations. Therefore, in this paper, we propose a medium access scheduling scheme, which adjusts the time interval for accessing to the shared transmission medium according to the amount of data for generating respective sensor node, and a priority control algorithm, which temporarily adjusts the priority of the sensor node that causes transmission concession due to the data priority until next successful transmission to ensure fairness.

• Journal of Korean Society of Forest Science
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• v.112 no.4
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• pp.544-553
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• 2023

The purpose of this study was to reveal the thermal comfort and physiological and psychological effects of spending time in broad-leaved forests in suumer. Thirty-one university students (with an average age of 21.4 ± 2.1 years) participated in the study, and a within-subjects experimental design methodology was used. The participants moved to an experimental site (with a crown closure of 76.6%) or a control site (25.9%), sat on a chair to eliminate the impact of movement, and rested for 5 minutes with closed eyes. At this time, thermal comfort, heart rate variability, heart rate, and forehead temperature were continuously measured. After that, blood pressure and pulse rate were measured, and a subjective evaluation was conducted. As a result, spending time at an experimental site showed a statistically significant decrease in the predicted mean vote and the percentage of dissatisfied values, enhancement of parasympathetic nerve activity, decrease of forehead temperature, diastolic blood pressure, heart rate, pulse rate, and improvement of personal thermal sensation (thermal sensation vote and comfort sensation vote). In conclusion, it was found that a forest with high crown closure reduces thermal stress and induces physiological and psychological relaxation.

• Journal of Advanced Navigation Technology
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• v.14 no.3
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• pp.439-445
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• 2010

The signal transmission of human body is processed by the action potential from each cell unit. This kind of action potential is taken place and transmitted by the ions through cell membrane, and ultimately explained as an electrical signal concept. The fact that the information is established as an electrical status as well as various senses from the bio-organozm has been addressed through several studies. By the way, this nervous transmission relation has been described and analyzed qualitatively in the mean time. I established new algorithm to analyze these relations quantitatively and implemented them using existing bio-data in this paper. The study, however, was limited to underthreshold potential to excite the nervous system against the outer stimulation. This is very much analog to electrical transient of the switching circuit, and therefore, I analyzed it based on this analog. I made it clear that the results derived here is the basis further study topic.

• Journal of the Korean Applied Science and Technology
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• v.35 no.2
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• pp.509-518
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• 2018

The purpose of this study was myokine product and role with physical activity and literature review. There is accumulating epidemiological evidence that a physically active life plays an independent role in the protection against type 2 diabetes, cardiovascular disease, colon cancer, dementia and even depression. And myokine has been regarded an important factor of exercise training and brain growth factor for the prevention of Alzheimier's disease. During exercise the release of anti-inflammatory myokine from contracting muscle controled the metabolic response, and IL-4, IL-6, IL-7, IL-10, and IL-15 controled muscle hypertrophy, myogenesis and angiogenenesis. IL-6 promoted the lipid metabolism through AMPK activation. IL-1Ra, IL-10 and sTNF-R inhibited $TNF-{\alpha}$ as the pro-inflammatory cytokine. IL-15 increased the releasing volume from contracting muscle, and promoted the anabolic factor of muscle growth. IL-7 and IL-8 activated the angiogenesis through the more activation of C-X-C receptor signal transmission.

• The Korean Journal of Applied Statistics
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• v.21 no.6
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• pp.1027-1035
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• 2008

This research is aimed to investigate the effect of repetitive dive on physiological reactions, change of stress hormones in no decompression limit of sport SCUBA dive, an emerging recreational activity recently. In order to compare physiological reactions prior to and after the initial dive and after repetitive dive at a certain depth of a place, eight adult male divers with more than forty dives, who reside in Busan and were certified, were selected. The research results obtained from the procedures described above are follows: First, for physiological reactions, heart rates, temperatures, and systolic blood pressures had significant difference among prior to and after the initial dive and after the repetitive dive, while diastolic blood pressures did not show remarkable difference as it increased before and after the first dive but decreased following the repetitive dive again. Second, for change of stress hormones, it was not significantly different prior to and after the initial dive and following the repetitive dive, as well as before and during the first dive and the repetitive dive.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.05a
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• pp.397-399
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• 2021

The increase in single-person households and the development of Home IoT technology make it important to improve the convenience of the residential environment. In addition, the increase in indoor activities caused by COVID-19 calls for the development of products to make life more convenient for single-person households. This trend of increased indoor activity has made it easier to interact with the current residential environment than before, and as a result, the need to develop technology for Home IoT is emerging. Therefore, the Home IoT system will be developed to monitor the information needed to maintain an ideal indoor environment such as temperature, humidity, and fine dust. The system will also interact with users, and propose a system that improves safety in indoor activities by equipping the home with IoT sensors for preventing safety accidents such as gas leakage and fire.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.48 no.2
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• pp.127-137
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• 2011

We have developed a wearable device that can convert sensor data into real-time step counts and activity levels. Sensor data on gait were acquired using a triaxial accelerometer. A test was performed according to a test protocol for different walking speeds, e.g., slow walking, walking, fast walking, slow running, running, and fast running. Each test was carried out for 36 min on a treadmill with the participant wearing a portable gas analyzer (K4B2), an Actical device, and the device developed in this study. The signal vector magnitude (SVM) was used to process the X, Y, and Z values output by the triaxial accelerometer into one representative value. In addition, for accurate step-count detection, we used three algorithms: an heuristic algorithm (HA), the adaptive threshold algorithm (ATA), and the adaptive locking period algorithm (ALPA). A regression equation estimating the energy expenditure (EE) was derived by using data from the accelerometer and information on the participants. The recognition rate of our algorithm was 97.34%, and the performance of the activity conversion algorithm was better than that of the Actical device by 1.61%.