• Science of Emotion and Sensibility
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• v.25 no.2
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• pp.79-86
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• 2022

With external air pollution forcing many people indoors, new methods of facilitating healthier indoor life are necessary. This study, therefore, investigates the effects of indoor oxygen concentration and respiration methods on biosignals and cognitive ability. The study included twenty healthy subjects who inhaled air through a mask from a gas delivery system. All subjects were asked to perform three types of breathing (nasal, oral, and oral breathing with high oxygenation) and respond to cognitive stimuli (rest close eye, rest open eye, 1-back and 2-back working memory tasks). The changes in cognitive load according to respiration were analyzed by measuring response time, accuracy, and biosignals to stimuli. The result showed that, in all three respirations, heart rate significantly increased with the increase in cognitive load. Also, in oral respiration, the airway respiration rate significantly increased according to the increase in cognitive load. The change appeared to compensate for insufficient oxygen supply in oral respiration during cognitive activity. Conversely, there was no significant change in airway respiration rate during oral respiration with a high concentration oxygen supply as in nasal respiration. This result suggests that a high concentration oxygen supply might play a role in compensating for insufficient oxygen concentration or inefficient oxygen inhalation, such as oral respiration. Based on the results of this study, a follow-up study is necessary to determine the impact of changes in the autonomic nervous system, such as stress and emotions, to find out more precise and comprehensive effects of oxygen concentration and breathing type.

• The Journal of the Convergence on Culture Technology
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• v.5 no.4
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• pp.93-98
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• 2019

The purpose of this study was to identify and analyze the rate of change of air respirator consumption based on field fire fighting activities, The results of the experiment are as follows. The mean air consumption of the Five subjects was $15.56{\ell}/min$ when standing still, $32.43{\ell}/min$ when walking with normal pace, $43.07{\ell}/min$ when the fire hoses was expanded and arranged, $55.28{\ell}/min$ when climbing stairs, The situation of running up the stairs and hitting the hammer continuously increases to $127.14{\ell}/min$, which means that the consumption of air increases according to the energy consumption. Despite being the oldest, Experimental subject A was $13.23{\ell}/min$ when standing still, $29.33{\ell}/min$ when walking normally, and $41.08{\ell}/min$ when the fire hose was deployed and arranged. This is a result of familiarity with deep and slow breathing methods. The average respiratory use rate of subjects D was $63.58{\ell}/min$. The reason for this is that obesity seems to increase the air consumption, and it is considered that the physical strength is exhausted by the action of the hammer, which has a greater influence on the increase of air consumption. The subject E had significantly lower air respiratory use rate of $49.90{\ell}/min$. The reason for this is that the age of E is the youngest among the subjects, and it is presumed that it possesses strong physical strength.

• International journal of advanced smart convergence
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• v.11 no.4
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• pp.240-246
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• 2022

In order to measure the respiratory rate, one of the major vital signs, many devices have been developed and related studies have been conducted. In particular, as the number of wearers of respirators increases in the COVID-19 pandemic situation, studies have been conducted to measure the respiratory rate of the wearer by attaching an electronic sensor to the respirator, but most of them are cases in which an air flow sensor or a microphone sensor is used. In this study, we design and develop a system that measures the respiratory rate of the wearer using an air pressure sensor in a respirator. Air pressure sensors are inexpensive and consume less power than the other sensors. In addition, since the amount of data required for calculation is small and the algorithm is simple, it is suitable for small-scale and low-power processing devices such as Arduino. We developed an algorithm to measure the respiratory rate of a respirator wearer by analysing air pressure change patterns. In addition, variables that can affect air pressure changes were selected, and experimental scenarios were designed according to the variables. According to the designed scenario, we collected air pressure data while the respirator wearer was breathing. The performance of the developed system was evaluated using the collected data.

• Korean Journal of Ichthyology
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• v.17 no.4
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• pp.241-247
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• 2005

To observe the respiratory system in relation to the air-breathing organ in Iksookimia longicorpa, micro-anatomical investigation was performed on the epidermis and on intestinal tract fragments. The epidermis was distinguished by two types of skin glands, a small mucous cell and a large club cell. The mucous cell was acid sulfomucins (some sialomucins), but the club cell did not give any histochemical tests for mucosubstances. The presence of a well defined lymphatic system with small lymphocytes was established in the stratum germinativum layer of the epidermis. A large number of blood capillaries run very close to each other just below the basement membrane. The straight intestinal tract is divided into an intestine and rectum, which consisted of a mucosa (epithelial layer), lamina propria-submucosa, muscularis, and serosa. The intestine and rectum have shorter mucosal folds and a thinner wall. The majority of the epithelial mucous cells contain acid sulfomucines. Based on the above results, I. longicorpa adapts to poor dissolved oxygen conditions by using an additional respiratory system using air through the epidermis, not the intestines.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.10
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• pp.966-978
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• 2011

Transpiration cooling is the most effective cooling technique for the high-performance liquid rockets and air-breathing engines operating in aggressive environments with higher pressures and temperatures. When applying transpiration cooling, combustor liners and turbine blades/vanes are cooled by the coolant(air or fuel) passing through their porous walls and also the exit coolant acting as an insulating film. Practical implementation of the cooling technique has been hampered by the limitations of available porous materials. But advances in metal-joining techniques have led to the development of multi-laminate porous structures such as Lamilloy$^{(R)}$ fabricated from several diffusion-bonded, etched metal thin sheets. And also with the availability of lightweight, ceramic matrix composites(CMC), transpiration cooling now seems to be a promising technique for high-performance engine cooling. This paper reviews recent research activities of transpiration cooling and its applications to gas turbines, liquid rockets, and the engines for hypersonic vehicles.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.493-496
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• 2005

For home healthcare, the unconstrained measurement of physiological signal is highly required to avoid the inconvenience of users. The recording and analysis of the fundamental parameters during sleep like respiration and heart beat provide valuable information on his/her healthcare. Using the air mattress sensor system, the respiration and heart beat movements can be measured without any harness or sensor on the subject's body. The differential measurement technique between two air cells is adopted to enhance the sensitivity. The balancing tube between two air cells is used to increase the robustness against postural changes during the measurement period. The meaningful frequency range could be selected by the pneumatic filter with balancing tube. ECG (Electrocardiography) and respiration sensor (plethysmography) were measured for comparison with the signal from air mattress. To extract the heart beat information from air pressure sensor, digital signal processing technique was used. The accuracy for breathing interval and heart beat monitoring was acceptable. It shows the potentials of air mattress sensor system to be the unconstrained home sleep monitoring system.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11b
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• pp.190-193
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• 2005

The air filter in engine intake system filters the dirt in the breathing air but also it attenuates the noise although the phenomenon has been regarded negligible. For the analysis of the acoustical performance of air filter, an acoustical model is suggested in this paper. The air filter consists of a porous filter element, which catches the particulate dirt, and a plastic filter box, which supports the filter element. Fibrous structure of the filter element is modeled as a micro-perforated panel using the flow resistivity and porosity. The pleated geometry of the filter element is modeled as two coupled ducts and a mathematical model is developed for the analysis of sound propagation. The filter box Is modeled as a rigid rectangular box. By combining two models, a 4-pole transfer matrix for the air filter is derived. The transmission loss calculated using the transfer matrix of the suggested model is compared with the measured data. Reasonably good agreement is observed. The result can be improved by considering the visco-thermal effect in modeling, in particular at a frequency range near the troughs of TL curve.

• Biomolecules & Therapeutics
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• v.7 no.2
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• pp.121-126
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• 1999

In an attempt to define the effects of hyperbaric oxygen treatment on the lipid peroxidation and oxygen free radical reactions in rats exposed to carbon monoxide, we studied malondialdehyde (MDA) level and activities of catalase and superoxide dismutase in the kidney of the rats exposed to carbon monoxide. Male Sprague-Dawley albino rats weighing 240 to 260 gm were used. Experimental groups consist of Control group (=breathing with air), HBO group (=exposed to hyperbaric oxygen 〔HBO, 3ATA, 100%〕 after air breath), CO group (=exposed to CO〔3,970 ppm〕after air breath), CO-Air group (=exposed to CO after air breath followed by air breath) and CO-HBO group (=exposed to CO after air breath followed HBO treatment). The CO group showed significantly higher MDA level, catalase activity and SOD activity as compared to that of control group. The CO-HBO group showed significantly lower MDA level as compared to that of CO group, and did not show significantly lower catalase activity and SOD activity as compared to that of CO group. These results suggest that the excessive oxygen free radicals is an important determinant in pathogenesis of CO-induced nephrotoxicity and HBO inhibits the lipid peroxidation caused by excessive oxygen free radicals in the kidney of the rats exposed to carbon monoxide.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2002.05a
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• pp.31-36
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• 2002

Recently, more interests in surface treatment of structure with water repellent agent are steadily increased, But, investigation of its properties such as protection, durability, morphology of micro structure is not sufficient. Therefore, This paper is aimed for the investigation of water repellent property and change of morphology of micro pores in mortar that is treated by water repellent agent(Inorganic polymer based material). Water repellent property, water absorption coefficient, air permeability, porosity and the observation of micro structure was investigated in different water repellent agent type. The test results indicated that water repellent treated mortar showed low absorption coefficient and air permeability(breathing effect). This is why inorganic polymer is coated at the wall of capillary and micro pores, also, the volume of micro pore is reduced without the change of morphology in micro structure.

• Journal of Korean Society for Atmospheric Environment
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• v.17 no.3
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• pp.241-249
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• 2001

A report by the National Research Council in the United States suggested that many lung cancer deaths each year are associated with breathing radon in indoor air. Most of the indoor radon comes directly from soil beneath the basement of foundation. Recently, radon released from groundwater is found to contribute to the total inhalation risk from indoor air. This study presents the assessment of a exposure to radon released from the groundwater into indoor air. At first, a 3-compartment model is describe the transfer and distribution if radon released from groundwater in a house through showering, washing clothes, and flushing toilets. The model is used to estimate a daily human exposure through inhalation of such radon for adults based on two sets of exposure scenarios, Finally, a sensitivity analysis is used to identify important parameters. The results obtained from the study would help to increase the understanding of risk assessment issues associated with the indoor radon released from groundwater.