Siyeon Kim

Diving bradycardia of elderly Korean women divers, haenyeo, in cold seawater: a field report

The purpose of the present field study was to explore diving patterns and heart rate of elderly Korean women divers (haenyeo) while breath-hold diving in cold seawater. We hypothesized that the decreasing rate in heart rate of elderly haenyeos during breath-hold diving was greater and total diving time was shorter than those of young haenyeos from previous studies. Nine haenyeos participated in a field study [68 ± 10 yr in age, ranged from 56 to 83 yr] at a seawater temperature of 10 to 13 °C. Average total diving time including surface swimming time between dives was 253 ± 73 min (155–341 min). Total frequency of dives was 97 ± 28 times and they dived 23 ± 8 times per hour. All haenyeos showed diving bradycardia with a decreased rate of 20 ± 8% at the bottom time (101 ± 20 bpm) when compared to surface swimming time (125 ± 16 bpm) in the sea. Older haenyeos among the nine elderly haenyeos had shorter diving time, less diving frequencies, and lower heart rate at work (p<0.05). These reductions imply that haenyeos voluntarily adjust their workload along with advancing age and diminished cardiovascular functions.

Comparisons of Thermal Insulations between on Air-Cell Pack Embedded Jacket and Down Jackets

Abstract This study investigated the thermal insulation of an air-cell pack embedded jacket and down jackets tounderstand the potential of air-cell pack as a filler for winter outdoor wear. A thermal manikin measuredthe thermal insulation of the following jackets: HD (heavy down jacket, total weight (Tw) 750g, goosedown weight (Dw) 350g), LD (light down jacket, Tw 560g, Dw 140g), AF (air-cell pack embedded jacket,Tw 490g, trunk goose down in LD was replaced to air cell), F (film jacket, Tw 469g, but removed the airin the air-cell pack from the AF), and Control (control jacket, Tw 438g, removed the air-cell pack film fromthe F). Thermal insulations of each experimental condition were measured in a static standing posture. To-tal thermal insulations (IT) were 1.29clo (HD), 1.23clo (LD), 1.16clo (AF), 1.20clo (F), and 1.08clo (Con-trol). Body regional thermal insulation was higher in the chest and back than in the abdomen and hip in allconditions. The results suggest that an economical and versatile outdoor jacket with superior thermal insula-tion will be feasible if the air volume is properly controlled in air-cell pack embedded jackets in considera-tion of regional different distribution and used in combination with film and down.Key words: Thermal insulation, Air-cell pack embedded jacket, Down jacket, Thermal manikin, Clo; 보온력, 공기주입형 재킷, 다운재킷, 써멀 마네킨, 클로

Evaluation of Thermoregulatory Properties of Thermal Underwear Named as `Heating Underwear` using Thermal Manikin and Human Performance Test

This study evaluated the thermoregulatory properties of functional thermal underwear (‘heating underwear’) in markets using a thermal manikin and human wear trials. One ordinary thermal underwear (ORD) and two functional thermal underwear (HEAT1 and HEAT2; manufactured goods, HEAT1: moisture absorbing heat release mechanism, HEAT2: heat storage, release mechanism) were chosen. Thermo-physiological and subjective responses were evaluated at an air temperature of 5.0±0.5 o C and air humidity of 30±5%RH with five male subjects (21.6±1.3yr in age, 178.0±5.9cm in height, 68.2±5.9kg in body mass). Experimental conditions consisted of four ensembles that included winter clothes (Control: no underwear, ORD, HEAT1, HEAT2). Water-vapor resistance was greater in fabric of HEAT1 than others. The results were: 1) Total thermal insulation (IT) using a thermal manikin were not greater for HEAT1 (0.860clo) and HEAT 2 (0.873clo) than for ORD (0.886clo). 2) There were no significant differences in rectal temperature, mean skin temperature, heart rate and total body mass loss between the four conditions. Microclimate clothing temperature on the back was greater for ORD than for HEAT1 and HEAT2. Subjects felt more comfortable with HEAT1 than for others at rest. HEAT2 was higher in microclimate humidity when compared to other conditions. The results suggest that thermoregulatory properties of ‘heating underwear’ in market did not differ from those of ordinary thermal underwear in terms of total thermal insulation and thermoregulatory responses in a cold environment.

Skin sites to predict deep-body temperature while wearing firefighters’ personal protective equipment during periodical changes in air temperature

Abstract The aim of this study was to investigate stable and valid measurement sites of skin temperatures as a non-invasive variable to predict deep-body temperature while wearing firefighters’ personal protective equipment (PPE) during air temperature changes. Eight male firefighters participated in an experiment which consisted of 60-min exercise and 10-min recovery while wearing PPE without self-contained breathing apparatus (7.75 kg in total PPE mass). Air temperature was periodically fluctuated from 29.5 to 35.5 °C with an amplitude of 6 °C. Rectal temperature was chosen as a deep-body temperature, and 12 skin temperatures were recorded. The results showed that the forehead and chest were identified as the most valid sites to predict rectal temperature (R2 = 0.826 and 0.824, respectively) in an environment with periodically fluctuated air temperatures. This study suggests that particular skin temperatures are valid as a non-invasive variable when predicting rectal temperature of an individual wearing PPE in changing ambient temperatures. Practitioner Summary: This study should offer assistance for developing a more reliable indirect indicating system of individual heat strain for firefighters in real time, which can be used practically as a precaution of firefighters’ heat-related illness and utilised along with physiological monitoring.

Frequency of firefighters’ heat-related illness and its association with removing personal protective equipment and working hours

The purpose of this study was to examine the frequency of firefighters’ heat-related illness (HRI) in the line of duty with relation to resting/working hours and the behaviour of taking off PPE during rest periods based on nationwide survey (N=674). The results showed that 74.8% of firefighters experienced HRI symptoms and 5% of firefighters suffered from symptoms of HRI 20 times or more in a year. This study also showed a statistically significant correlation between working hours and removing PPE with the experience of HRI symptoms (p<0.05). In addition, removing PPE except the helmet was correlated with resting hours (p<0.001; Gloves: p=0.051), which indicates that removing PPE is related to resting time. This study revealed that firefighters routinely experienced mild HRI symptoms and the fatalities were just a tiny fraction. It is also emphasized that attention should be given on the significant role of taking off PPE during rest and on the standardized firefighters’ rehabilitation followed by its application.

Development of Firefighting Performance Test Drills while Wearing Personal Protective Equipment

A firefighting simulation was developed in order to assess the physical work capacity of firefighters. The simulation consisted of eight common firefighting tasks, including walking with radiant heat for 3 min while wearing full personal protective equipment (PPE). Nine professional firefighters performed the test a total of three times with a 5 min rest interval between each session. The entire series of tests took approximately 30 min to complete (381 ± 30 s.). Rectal temperatures were found to increase from 37.4 ±0.3 degrees C to 38.5 ±0.4 degrees C, while heart rates were found to increase from 92±18bpm to 185±13bpm during testing. Time to completion of the test drills and non-modified physical fitness values showed a significantly negative correlation (r = -0.728, p Language: ko

A real-time heat strain index using foot temperature and heart rate while wearing personal protective equipment in hot environments

Over the past century, a number of indices to assess heat stress and strain in hot environments have been developed, but there are few non-invasive indices to evaluate the heat strain of workers wearing personal protective equipment. ISO 7933 [1] presents an analytical method to determine heat stress using calculation of the predicted heat strain but the calculation is complicated to apply for real-time monitoring. Moran and colleagues [2,3] derived a simple and useful index based on rectal temperature (Tre) and heart rate (HR) (Physiological Strain Index, PSI) but the index is limited at work in fields because of the direct measurement of rectal temperature. The purpose of this study was to present a non-invasive method to monitor heat strain in real-time using foot temperature (Tfoot) and HR of workers wearing personal protective equipment with protective boots in hot environments.