• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.7
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• pp.380-394
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• 2015

This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2014. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering have been reviewed as groups of heat and mass transfer, cooling and heating, and air-conditioning, the flow inside building rooms, and smoke control on fire. Research issues dealing with duct and pipe were reduced, but flows inside building rooms, and smoke controls were newly added in thermal and fluid engineering research area. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results for thermal contact resistance measurement of metal interface, a fan coil with an oval-type heat exchanger, fouling characteristics of plate heat exchangers, effect of rib pitch in a two wall divergent channel, semi-empirical analysis in vertical mesoscale tubes, an integrated drying machine, microscale surface wrinkles, brazed plate heat exchangers, numerical analysis in printed circuit heat exchanger. In the area of pool boiling and condensing, non-uniform air flow, PCM applied thermal storage wall system, a new wavy cylindrical shape capsule, and HFC32/HFC152a mixtures on enhanced tubes, were actively studied. In the area of industrial heat exchangers, researches on solar water storage tank, effective design on the inserting part of refrigerator door gasket, impact of different boundary conditions in generating g-function, various construction of SCW type ground heat exchanger and a heat pump for closed cooling water heat recovery were performed. (3) In the field of refrigeration, various studies were carried out in the categories of refrigeration cycle, alternative refrigeration and modelling and controls including energy recoveries from industrial boilers and vehicles, improvement of dehumidification systems, novel defrost systems, fault diagnosis and optimum controls for heat pump systems. It is particularly notable that a substantial number of studies were dedicated for the development of air-conditioning and power recovery systems for electric vehicles in this year. (4) In building mechanical system research fields, seventeen studies were reported for achieving effective design of the mechanical systems, and also for maximizing the energy efficiency of buildings. The topics of the studies included energy performance, HVAC system, ventilation, and renewable energies, piping in the buildings. Proposed designs, performance performance tests using numerical methods and experiments provide useful information and key data which can improve the energy efficiency of the buildings. (5) The field of architectural environment was mostly focused on indoor environment and building energy. The main researches of indoor environment were related to the evaluation of work noise in tunnel construction and the simulation and development of a light-shelf system. The subjects of building energy were worked on the energy saving of office building applied with window blind and phase change material(PCM), a method of existing building energy simulation using energy audit data, the estimation of thermal consumption unit of apartment building and its case studies, dynamic window performance, a writing method of energy consumption report and energy estimation of apartment building using district heating system. The remained studies were related to the improvement of architectural engineering education system for plant engineering industry, estimating cooling and heating degree days for variable base temperature, a prediction method of underground temperature, the comfort control algorithm of car air conditioner, the smoke control performance evaluation of high-rise building, evaluation of thermal energy systems of bio safety laboratory and a development of measuring device of solar heat gain coefficient of fenestration system.

• Journal of Animal Environmental Science
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• v.16 no.3
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• pp.193-204
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• 2010

The goal of this study was to develop a high-rise hog building(HRHB) for growing-fattening stages. HRHB was two story building and was suitable for specific environment in Korea. Manure was treated in a first floor and pigs were raised on the slatted second floor. Three ventilation systems - 1) duct inlet to wall exhaust system(V1), 2) eave inlet to wall exhaust system(V2), and 3) ceiling inlet to wall exhaust system(V3) - were used. This experiment was conducted during winter and from summer to fall. Air temperature, air speed, ammonia, hydrogen sulfide in HRHB, and swine growth rate were measured. During winter, air temperature in V1 system tended to be slightly high without any effect of outside air temperature. Maximum temperature from summer to fall was between 33.4 and $33.8^{\circ}C$ and there was no significant difference among systems. Continuously measured daily temperature was lower in V2 system than other systems and the fluctuation of air temperature was high. Air speed in V1 and V2 systems were similar (0.02~0.21 m/s), and was 0.04~0.15 m/s in V3 during winter. From summer to fall, air speed in V1, V2, and V3 systems were 0.10~0.41 m/s, 0.10~0.83 m/s, and 0.11~0.26 m/s, respectively. V2 system showed bigger fluctuation of air speed than other systems. During winter, the highest concentrations of ammonia in V1, V2, and V3 systems were 7.0, 3.5, and 8.7 ppm, respectively. Hydrogen sulfide was not detected. The highest concentrations of ammonia from summer to winter in V1, V2, and V3 systems were 6.1, 2.8, and 5.6 ppm, respectively. Swine growth showed no statistical significance among systems. However, daily weight gain was approximately 4% higher in V1 and V3 than in V2. Feed intake/daily weight gain was approximately 4% higher in V1 than other systems. From summer to fall, daily weight gain in V1 and V3 tended to approximately 3% higher than other systems, and feed intake/daily weight gain was approximately 2% higher in V1 than other systems. Hence, V2 system for the ventilation system of HRHB should not be utilized.

• Tuberculosis and Respiratory Diseases
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• v.48 no.5
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• pp.766-772
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• 2000

Background : Pressure rise time (PRT) is the time in which the ventilator aclieves the set airway pressure in pressure-targeted modes, such as pressure control ventilation (PCV). With varying PRT, in principle, the peak inspiratory flow rate of the ventilator also varies. And if PRT is set to a shorter duration, the effective duration of target pressure level would be prolonged, which in turn would increase inspiratory tidal volume(Vti) and mean airway pressure (Pmean). We also postulated that the increase in Vti with shortening of PRT may relate inversely to the patients' basal airway resistance. Methods : In 13 paralyzed patients on PCV (pressure control 18$\pm$9.5 cm $H_2O$ $FIO_2\;0.6\pm0.3$, PEEP 5$\pm$3 cm $H_2O$, f 20/min, I : E1 : 2) with Servo 300 (Siemens-Elema, Solna, Sweden) from various causes of respiratory failure, PRT of 10 %, 5 % and 0 % were randomly applied. At 30 min of each PRT trial, peak inspiratory flow (PIF, L/sec), Vti (ml), Pmean (cm $H_2O$) and ABGA were determined. Results : At PRT 10%, 5%, and 0%, PIF were 0.69$\pm$0.13, 0.77$\pm$0.19, 0.83$\pm$0.22, respectively (p<0.001). Vti were 425$\pm$94, 439$\pm$101, 456$\pm$106, respectively (p<0.001), and Pmean were 11.2$\pm$3.7, 12.0$\pm$3.7, 12.5$\pm$3.8, respectively (p<0.001). pH were 7.40$\pm$0.08, 7.40$\pm$0.92, 7.41$\pm$0.96, respectively (p=0.00) ; $PaCO_2$ (mm Hg) were 47.4$\pm$15.8, 47.2 $\pm$15.7, 44.6$\pm$16.2, respectively (p=0.004) ; $PAO_2-PaO_2$ (mm Hg) were 220$\pm$98, 224$\pm$95, 227$\pm$94, respectively (p=0.004) ; and $V_n/V_T$ as determined by ($PaCO_2-P_E-CO_2$)/$PaCO_2$ were 0.67$\pm$0.07, 0.67$\pm$0.08, 0.66$\pm$0.08, respectively (p=0.007). The correlation between airway resistance and change of Vti from PRT 10% to 0% were r= -0.243 (p=0.498). Conclusion : Shortening of pressure rise timee during PCV was associated with increased tidal volume, increased mean airway pressure and lower $PaCO_2$.

• Journal of Industrial Convergence
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• v.18 no.5
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• pp.30-35
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• 2020

The purpose of this study is to find out the effect of aerobic exercise through convergence on exhaled carbon monoxide and cardiorespiratory function of female college students who participated in nonsmoking. The subjects were female college students from University D in Metropolitan City D, and those who started smoking 2 years ago and who do not engage in regular physical activities were first selected, and a total of 18 people who indicated their intention to participate in the experiment were selected to receive a pledge of nonsmoking and consent to the experiment. The selected subjects were classified into 9 people in the exercise group and 9 in the control group by wireless assignment, and individual exercise intensity was set through the maximum exercise load test to establish an accurate exercise program. Individual exercise intensity is set to 50%HRmax for 1-3 weeks, 60%HRmax for 4-6 weeks, 70%HRmax for 7-9 weeks. In order to apply the correct exercise intensity during exercise, a Polar heart rate monitor was used for control and the following results were obtained. First, the change in carbon monoxide decreased by three levels from 21.17±3.67ppm (Red 2 16-25ppm, habitual smokers) before participation in the exercise group that participated in aerobic exercise for 9 weeks to 1.36±0.76ppm (Green, 0-6ppm, non-smokers) after participation, and the control group also showed the same effect from 22.35±2.08ppm (Red 2 16-25ppm, habitual smokers) to 2.81±0.51ppm (Green, 0-6ppm, non-smokers). Second, the change in cardiorespiratory function showed a significant increase in all of the maximum oxygen intake, maximum heart rate, and maximum ventilation in the exercise group who participated in aerobic exercise for 9 weeks, but there was no significant change in the control group. Therefore, aerobic exercise showed the effect of improving the cardiorespiratory function by releasing carbon monoxide and supplying sufficient oxygen to various organs.

• 한국체육학회지인문사회과학편
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• v.58 no.4
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• pp.447-459
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• 2019

This study was conducted to investigate the differences between emotional responses and neurotransmitters in moderate-intensity continuous exercise (MICE) and high-intensity interval exercise (HIIE) in 30 low-active women. Both groups performed a designed acute treadmill exercise and repeated the same exercise three times at intervals of one week. MICE performed a 25-minute continuous exercise at 90% VT(ventilation threshold) after a 5-minute warm-up session at 50% VT and then cooled down for 5 minutes at 50% VT level. The HIIE was repeated 6 times for 2 minutes at 115% VT level, and the intermediate active recovery was repeated 4 times for 2 minutes at 85% VT level. The results of the statistical analysis are as follows. MICE was showed positive effect for feeling scale and PACES after exercise in the first experiment, but negative effect in the third experiment. Conversely, HIIE was showed negative effect for feeling scale and PACES after exercise in the first experiment, but positive effect in the third experiment. Neurotransmitters were significantly increased in all three groups after 10 minutes of exercise compared to before exercise. In summary, HIIE exercise may be a strategy to increase exercise compliance for low-active women.

• Tuberculosis and Respiratory Diseases
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• v.45 no.4
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• pp.813-822
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• 1998

Background: Extubation is recommended to be performed at minimum pressure support (PSmin) during the pressure support ventilation (PSV). In field, physicians sometimes perform additional 1 hr T-piece trial to the patient at PSmin to reduce re-intubation risk. Although it provides confirmation of patient's breathing reserve, weaning could be delayed due to increased airway resistance by endotracheal tube. Methods: To investigate the effect of additional 1 hr T-piece trial on weaning outcome, a prospective study was done in consecutive 44 patients who had received mechanical ventilation more than 3 days. Respiratory mechanics, hemodymic, and gas exchange measurements were done and the level of PSmin was calculated using the equation (PSmin=peak inspiratory flow rate $\times$ total ventilatory system resistance) at the 15cm $H_2O$ of pressure support. At PSmin, the patients were randomized into intervention (additional 1 hr T-piece trial) and control (extubation at PSmin). The measurements were repeated at PSmm, during weaning process (in cases of intervention), and after extubation. The weaning success was defined as spontaneous breathing more than 48hr after extubation. In intervention group, failure to continue weaning process was also considered as weaning failure. Results: Thirty-six patients with 42 times weaning trial were satisfied to the protocol. Mean PSmin level was 7.6 (${\pm}1.9$)cm $H_2O$. There were no differences in total ventilation times (TVT), APACHE III score, nutritional indices, and respiratory mechanics at PSmin between 2 groups. The weaning success rate and re-intubation rate were not different between intervention group (55% and 18% in each) and control group (70% and 20% in each) at first weaning trial. Work of breathing, pressure time product, and tidal volume were aggravated during 1 hr T-piece trial compared to those of PSmin in intervention group ($10.4{\pm}1.25$ and $1.66{\pm}1.08$ J/L in work of breathing) ($191{\pm}232$ and $287{\pm}217$cm $H_2O$ s/m in pressure time product) ($0.33{\pm}0.09$ and $0.29{\pm}0.09$ L in tidal volume) (P<0.05 in each). As in whole, TVT, and tidal volume at PSmin were significantly different between the patients with weaning success ($246{\pm}195$ hr, $0.43{\pm}0.11$ L) and the those with weaning failure ($407{\pm}248$ hr, $0.35{\pm}0.10$L) (P<0.05 in each). Conclusion : There were no advantage to weaning outcome by addition of 1 hr T-piece trial compared to prompt extubation to the patient at PS min.

• Tuberculosis and Respiratory Diseases
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• v.63 no.5
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• pp.423-429
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• 2007

Background: Alveolar recruitment (RM) is one of the primary goals of respiratory care for an acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). The purposes of alveolar recruitment are an improvement in pulmonary gas exchange and the protection of atelectrauma. This study examined the effect and safety of the alveolar RM using pressure control ventilation (PCV) in early ALI and ARDS patients. Methods: Sixteen patients with early ALI and ARDS who underwent alveolar RM using PCV were enrolled in this study. The patients data were recorded at the baseline, and 20 minutes, and 60 minutes after alveolar RM, and on the next day after the maneuver. Alveolar RM was performed with an inspiratory pressure of $30cmH_2O$ and a PEEP of $20cmH_2O$ in a 2-minute PCV mode. The venous $O_2$ saturation, central venous pressure, blood pressure, pulse rate, $PaO_2/FiO_2$ ratio, PEEP, and chest X-ray findings were obtained before and after alveolar RM. Results: Of the 16 patients, 3 had extra-pulmonary ALI/ARDS and the remaining 13 had pulmonary ALI/ARDS. The mean PEEP was 11.3 mmHg, and the mean $PaO_2/FiO_2$ ratio was 130.3 before RM. The $PaO_2/FiO_2$ ratio increased by 45% after alveolar RM. The $PaO_2/FiO_2$ ratio reached a peak 60 minutes after alveolar RM. The Pa$CO_2$ increased by 51.9 mmHg after alveolar RM. The mean blood pressure was not affected by alveolar RM. There were no complications due to pressure injuries such as a pneumothorax, pneumomediastinum, and subcutaneous emphysema. Conclusion: In this study, alveolar RM using PCV improved the level of oxygenation in patients with an acute lung injury and acute respiratory distress syndrome. Moreover, there were no significant complications due to hemodynamic changes and pressure injuries. Therefore, alveolar RM using PCV can be applied easily and safely in clinical practice with lung protective strategy in early ALI and ARDS patients.

• Clinical and Experimental Pediatrics
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• v.57 no.5
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• pp.222-225
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• 2014

Purpose: A recent study analyzing several cytokines reported that long cardiopulmonary bypass (CPB) time and long aortic cross clamp (ACC) time were accompanied by enhanced postoperative inflammation, which contrasted with the modest influence of the degree of hypothermia. In this present study, we aimed to examine the effect of CPB temperature on the clinical outcome in infants undergoing repair of isolated ventricular septal defect (VSD). Methods: Of the 212 infants with isolated VSD who underwent open heart surgery (OHS) between January 2001 and December 2010, 43 infants were enrolled. They were classified into 2 groups: group 1, infants undergoing hypothermic CPB ($26^{\circ}C-28^{\circ}C$; n=19) and group 2, infants undergoing near-normothermic CPB ($34^{\circ}C-36^{\circ}C$; n=24). Results: The age at the time of the OHS, and number of infants aged<3 months showed no significant differences between the groups. The CPB time and ACC time in group 1 were longer than those in group 2 (88 minutes vs. 59 minutes, P =0.002, and 54 minutes vs. 37 minutes, P =0.006 respectively). The duration of postoperative mechanical ventilation was 1.6 days in group 1 and 1.8 days in group 2. None of the infants showed postoperative neurological and developmental abnormalities. Moreover, no postoperative differences in the white blood cell count and C-reactive protein levels were noted between two groups. Conclusion: This study revealed that hypothermic and near-normothermic CPB were associated with similar clinical outcomes and inflammatory reactions in neonates and infants treated for simple congenital heart disease.

• Journal of Yeungnam Medical Science
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• v.33 no.2
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• pp.85-89
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• 2016

Background: Formaldehyde is used to preserve cadaver in medical schools, and students are exposed to formaldehyde during cadaver dissection classes. When humans are exposed to formaldehyde, it induces mucosal inflammation, skin inflammation, and declining of neurobehavioral function including attention and memory executive functions. The purpose of this study is to identify the effects of formaldehyde exposure on student's neurobehavioral performance during cadaver dissection classes. Methods: The level of formaldehyde was measured in a cadaver dissection class. A total of 16 students were randomly divided into two groups. One group wore respiratory protection masks, while the other group did not. Among many subtests in Korean Computerized Neurobehavioral test, backward digit span was tested on all subjects before and after the class. Results: The length of memorized digit span between the two groups was not significant; however there was a greater decrease in neurobehavioral function after formaldehyde exposure in the non-mask group than the mask group. Conclusion: Formaldehyde exposure during cadaver dissection may likely decrease neurobehavioral performance of students. Therefore, proper ventilation system and respiratory protective equipment are necessary to protect medical school students from adverse effects of formaldehyde exposure.

• International Journal of Fluid Machinery and Systems
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• v.4 no.3
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• pp.307-316
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• 2011

In order to clarify the features of tip leakage vortex near blade tip region in a half-ducted axial fan with large bellmouth, the experimental investigation was carried out using a 2-dimensional LDV system. Three sizes of tip clearance (TC) were tested: those sizes were 1mm (0.55% of blade chord length at blade tip), 2mm (1.11% of blade chord length at blade tip) and 4mm (2.22% of blade chord length at blade tip), and those were shown as TC=1mm, TC=2mm and TC=4mm, respectively. Fan characteristic tests and the velocity field measurements were done for each TC. Pressure - flow-rate characteristics and two-dimensional velocity vector maps were shown. The vortex trace and the vortex intensity distribution were also illustrated. As a result, a large difference on the pressure - flow-rate characteristics did not exist for three tip clearance sizes. In case of TC=4mm, the tip leakage vortex was outflow to downstream of rotor was not confirmed at the small and reference flow-rate conditions. Only at the large flow-rate condition, its outflow to downstream of rotor existed. In case of TC=2mm, overall vortex behaviors were almost the same ones in case of TC=4mm. However, the vortex trace inclined toward more tangential direction. In case of TC=1mm, the clear vortex was not observed for all flow-rate conditions.