• Journal of Veterinary Science
• /
• v.21 no.2
• /
• pp.27.1-27.10
• /
• 2020

The efficacies of a supraglottic airway device (SGAD) and an endotracheal tube (ETT) in cats under general anesthesia with volume-controlled ventilation (VCV) were compared. Thirty healthy cats were randomly allocated for airway control using either an SGAD or an ETT. Five tidal volumes (6, 8, 10, 12, and 14 mL/kg) were randomly tested, and respiratory rates were adjusted to achieve a minute ventilation of 100 mL/kg/min. The dose of propofol necessary to insert the SGAD or ETT, the static respiratory pressure, leakage during VCV, and end tidal CO₂ (ETCO₂) were recorded. Dosages of propofol and static respiratory measurements for the SGAD and ETT groups were compared using a t-test. The distribution of leakages and hypercapnia (ETCO₂ > 45 mmHg) were compared using Fisher's exact test. A significance level of p < 0.05 was established. No significant difference in dose of propofol was observed between the SGAD and ETT groups (7.1 ± 1.0, 7.3 ± 1.7 mg/kg; p = 0.55). Static resistance pressure of the SGAD (22.0 ± 8.1 cmH₂O/L/sec) was significantly lower than that of the ETT (36.6 ± 12.9 cmH₂O/L/sec; p < 0.01). Of the 75 trials, leakage was more frequent when using an SGAD (8 events) than when using an ETT (1 event; p = 0.03). Hypercapnia occurred more frequently with SGAD (18 events) than with ETT (3 events; p < 0.01). Although intubation with an ETT is the gold standard in small animal anesthesia, the use of an SGAD can reduce airway resistance and the work of breathing. Nonetheless, SGAD had more dead space and the tidal volume for VCV needs adjustment.

• Journal of Animal Reproduction and Biotechnology
• /
• v.38 no.2
• /
• pp.70-76
• /
• 2023

Background: Despite considerable technological advancements, polyspermy remains a significant challenge in in vitro fertilization (IVF) procedures in pigs, disrupting normal embryonic development. Here, we aimed to determine whether optimal fertilization conditions reduce the polyspermy incidence in pigs. Methods: In vitro-matured oocytes were co-incubated with sperm according to a modified two-step culture system. Results: In the first experiment, oocytes were briefly co-incubated with sperm, washed in IVF medium, and then moved to fresh IVF medium for 5 or 6 h. Although the 6 h sperm-free cultured group had a higher penetration rate than the 5 h cultured group, the polyspermy rate significantly increased in the 6 h sperm-free cultured group. The gamete co-incubation period was either 20 or 40 min. The 40 min cultured group had a higher rate of blastocyst formation and number of total cells in blastocysts than the 20 min cultured group. In experiment 2, oocytes were inseminated with sperm separated by Pecroll treatment. Percoll treatment increased the rate of oocyte penetration and blastocyst formation compared to the control. In experiment 3, fertilized oocytes were cultured in 25 µL microdroplets (10 gametes/drop) or 500 µL (100 gametes/well) of culture medium in 4-well plates. The large volume of medium significantly reduced the number of dead oocytes and increased the rate of blastocyst formation compared to the small volume. Conclusions: Collectively, these results demonstrate that various fertilization conditions, including modified co-culture period, active sperm separation, and culture medium volume, enhance fertilization efficiency and subsequent embryonic development by decreasing polyspermy occurrence.

• Journal of Korean Society of Forest Science
• /
• v.103 no.3
• /
• pp.422-430
• /
• 2014

This study was conducted to investigate growth changes of DBH, height, crown width, volume, stem biomass, and dead trees after thinning treatments with different thinning intensity for Korean white pine (Pinus koraiensis) plantation. First thinning was applied with 29~69% intensity based on number of trees in 19-yearold plantation, and trees were measured three times: right after thinning (19-year-old), 5 years later (24-yearold), 12 years later (29-year-old). In the case of DBH growth, average DBH growth of heavily thinned plots was 19.6~19.9% higher 5 years later, and 13.3~24.7% higher 12 years later, compared to that of unthinned plots. Initial diameter growth rate was higher than late growth rate. The proportion of large pole candidates ($DBH{\geq}25cm$) was 31% in heavily thinned plot while only 2% was shown in unthinned plot. No difference was shown in height growth depending on plots, and average crown width growth in heavily thinned plots was 30.6~33.3% higher, 5 years later, and 35.0~40.0% higher, 12 years later, compared to that of unthinned plots. Average volume growth of individual trees in heavily thinned plots was 39.8~46.8% higher, 5 years later, and 23.0~52.0% higher, 12 years later, compared to unthinned plots. The maximum volume and biomass per unit area were shown in unthinned plot; the volume and biomass 5 and 12 years later after thinning were $133m^3/ha$ (51 kg/ha) and $344m^3/ha$ (132 kg/ha), respectivily. The significant difference appeared in crown width, volume, and biomass depending on thinning intensity. No dead trees occurred in heavily thinned plots for 12 years after thinning, while mortality rate in unthinned plots was 27.9~37.8%. As a result of analyzing annual increment using cores to determine the timing of second thinning, it suggested that second thinning be suitable around 10 years after first thinning.

• Journal of Environmental Health Sciences
• /
• v.46 no.1
• /
• pp.78-87
• /
• 2020

Objectives: To identify the degree of physical burden, a determination was undertaken of dust collection efficiency, inhalation pressure, and CO₂ concentration related to health masks certified by the Ministry of Food and Drug Safety (MFDS). Methods: Twenty health masks were purchased on the market. Dust collection efficiency and inhalation pressure were determined in the same manner as in MFDS certification testing, respectively using TSI Model 8130 (TSI, U.S.) and ART Plus (Korea). CO₂ concentrations for 20 subjects using a CO₂ analyzer (G100, G150, Geotechnical Instrument Ltd., UK) were measured with a similar method as a total inward leakage test. In addition to CO₂ levels, dead space volumes in the masks was determined for predicting concentrations of CO₂ in inhalation air. Results: Most of the dust collection efficiencies found for the 20 masks were far higher than the standard. Four KF94s met KF99 and four KF80s even met KF94. Most inhalation pressures were also much lower than the standard, with many almost one-half of the standard. The mean and standard deviation of CO₂ concentration in the mask were 2.9±0.44%. Considering dead volume, the prediction for CO₂ concentration in the inhalation air was 4,395±1,266 ppm. Conclusions: For healthy men and women, the dust collection efficiency and inhalation pressure of health masks were not at a level that would affect their health. Although CO₂ levels in the inhalation air were predicted not to affect health, research on the physiological effects of health masks on Koreans is needed for more precise research.

• Membrane Journal
• /
• v.23 no.4
• /
• pp.257-266
• /
• 2013

The main purpose of this study is to develop a commercial scale of pervaporative process equipped with hollow fiber membrane modules, being able to effectually purify organic solvent at high temperature well over its boiling point under high vapor pressure. Three constituent technologies have been developed; 1) to fabricate braid-reinforced hollow fiber membrane stable in high pressure and high temperature application, 2) to design and fabricate a commercial scale of hollow fiber membrane module, and 3) to design and fabricate a pilot scale of pervaporation equipment system. The developed hollow fiber membrane possesses a membrane performance superior to the membrane of Sulzer (Germany) which is the most-well known for pervaporation process, and the membrane module equips hollow fiber membranes of $4.6m^2$ and the pervaporation system can treat organic liquid at 200 L/h, which is based on the dehydration of 95 wt% isopropyl alcohol (IPA). Since the membrane module is designed to flow in and pass through the inside of individual hollow fiber membrane, not to involve both the formation of feed's dead volume observed in flat-sheet membrane module and the channeling of feed occurring inside hollow fiber bundle which lower membrane performance seriously, it showed excellent separation efficiency. In particular, the module is inexpensive and has less heat loss into its surrounding, in compared with flat-sheet membrane module. In addition, permeant can be removed effectively from the outer surface of hollow fiber membrane because the applied vacuum is conveyed uniformly through space between fibers into respective fiber, even into one in the middle of the hollow fiber bundle in which the space between fibers is uniform in distance. Since the hollow fiber membrane pervaporation system is the first one ever developed in the world, our own unique proprietary technology can be secured, preoccupying technical superiority in export competitive challenges.

• Journal of the Korea Concrete Institute
• /
• v.29 no.4
• /
• pp.407-413
• /
• 2017

The fundamental property of magnesia phosphate cement (MPC) for concrete repair material was investigated in this research. For mechanical properties, setting time, compressive strength and tensile/flexural bond strength were measured, and hydration products were detected by X-ray diffraction. The specimens were manufactured with dead burnt magnesia and potassium dihydrogen phosphate was admixed to activate the hydration of magnesia and a borax was used as a retarder. To observe the pore structure and ionic permeability of MPC mortar, mercury intrusion porosimetry was performed together with rapid chloride penetration test (RCPT). As a result, time to set of Fresh MPC mortar was in range of 16 to 21 min depend on the M/P ratio. Borax helped delaying setting time of MPC to 68 min. The compressive strength of MPC with M/P of 4 was sharply developed to 30 MPa within 12 hours. The compressive strength of MPC mortar was in range of 11.0 to 30.0 MPa depend on the M/P ratio at 12 hours of curing. Both tensile and flexural bond strength of MPC to old substrate (i.e. MPC; New substrate to OPC; Old substrate) were even higher than ordinary Portland cement mortar (i.e. [OPC; New substrate] to [OPC; Old substrate]) does, accounting 19 and 17 MPa, respectively. The total pore volume of MPC mortar was lower than that of OPC mortar. MPC mortar had the entrained air void rather than capillary pore. The RCPT showed that total charge passed of OPC mortar had more than that of MPC mortar, which can be explained by the pore volume and pore distribution.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.39 no.9
• /
• pp.713-718
• /
• 2015

The purpose of this study is to realize compressor-performance improvements in the fuel economy of an automotive air-conditioning system. We conduct cooling performance tests in a compressor calorimeter test stand. To improve the cooling performance, we investigate the increase in the suction flow rate and the decrease in the discharge dead volume. Based on the results of the test, we found that the cooling capacity and the coefficient of performance (COP) of the compressors were improved as follows. The cooling performance improved greater at high speeds than low speeds in the case of an increase in the suction flow rate increase, and it improved more at low speeds than at high speed when there was a decrease in the discharge dead volume. When both of the above factors were included, we observed that the improvement effects were generally balanced for both high- and low-speed modes, and there was a significant improvement in the discharge temperature. The improvement was found to be about 3.2% at low speed, 8.3% at high speed during in cooling performance improvement, about 5.8% at low speed and about 6.2% at high speed in COP improvement, and there was a decrease of about $3^{\circ}C$ at low speed and a $5^{\circ}C$ decrease at high speed in discharge temperature.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.02a
• /
• pp.448-448
• /
• 2013

최근 생물학적 분석 기구에서 시료를 처리, 분리, 검출, 샘플링 또는 분석하기 위해 사용되는 마이크로펌프(Micropump)에 대한 관심이 높아지고 있다. 또한 전자소자의 성능과 신뢰성의 증진을 위한 전자소자의 열 문제를 해결하기 위해 냉각장치로 마이크로 펌프가 적용되기도 한다. 그 외에도 마이크로펌프는 다양한 분야에 응용이 가능하다. 마이크로펌프는 작동 방식에 따라 압전형, 공압형, 열공압형, 연동형 등의 여러 종류로 분류되고 있다. 그중에서도 최근에는 연동형 마이크로 펌프의 개발이 각광받고 있다. 기존의 연동형 펌프들은 다중 챔버를 가지고 있으며, 각각의 챔버 내에서 Dead volume이 많이 발생할 뿐만 아니라 이상적인 연동운동과는 차이가 많이 나는 문제점을 가지고 있다. 또한 압전방식과 열공압방식은 느린 응답성으로 인해 효율적인 유체 이동이 어렵다. 본 논문에서는 이상적인 연동운동을 구현하기 위하여 기존의 연동형 펌프의 단점을 보완하고, 하나의 챔버에 다중전극 구조를 가지는 정전기력방식의 연동형 펌프를 개발하였다. 정전기력방식으로 펌프를 구동함으로써, 저전력으로 펌프구동이 가능하며, 하나의 챔버에 다중전극을 설치함으로써 이상적인 연동운동을 재현하였다. 그리고 Dead volume을 최소화 하였다. 또한, 빠른 반응속도로 인해 효율적인 유체 이동을 실현시킬 수 있었다. 본 연구에서 제안된 마이크로 펌프의 구성은 크게 챔버, 박막, Inlet/outlet hole으로 구성되었다. 챔버는 Si-wafer에 wet etching 공정으로 제작 하였고 그 위에 알루미늄 박막을 200 nm 증착시켰다. 챔버는 가로 32 mm, 세로 5 mm, 깊이는 $15{\mu}m$, 부피는 $200{\mu}l$으로 제작되었다. 박막은 폴리이미드(polyimide)를 사용하여 $3{\mu}m$의 두께로 제작 되었으며, 폴리이미드 박막 사이에는 200 nm 두께의 4개의 알루미늄 박막 전극을 삽입시켰다. 삽입된 4개의 전극에 개별적인 전기신호를 보냄으로써 연동운동이 가능하다. Inlet/outlet hole은 직경 2 mm의 크기로 제작되었으며, 튜브를 연결하여 유체가 흐를 수 있는 체널을 형성하였다. 제작된 마이크로 펌프의 구동전압은 115 V이며, 인가되는 주파수를 1 Hz~100 KHz까지 변화시켜 유량을 측정하였다. 작동 유체는 공기이며, 유량측정은 튜브 내에 물방울을 삽입하여 시간에 따른 이동거리를 관측하였다. 측정결과 2.2 KHz에서 2.4 mm/min의 가장 높은 유량을 확인할 수 있었다. 본 연구를 통해 제안된 연동형 마이크로펌프는 이상적인 연동운동이 가능함으로써 기존의 연동형 방식의 문제점을 보완하였으며, 생명과학, 의학, 화학 등의 분야에서 적용이 가능하리라 기대된다.

• Tuberculosis and Respiratory Diseases
• /
• v.46 no.5
• /
• pp.662-673
• /
• 1999

Background : Pressure-controlled ventilation (PCV) is frequently used recently as the initial mode of mechanical ventilation in the patients with respiratory failure. Theoretically, because of its high initial inspiratory flow, pressure-controlled ventilation has lower peak inspiratory pressure and improved gas exchange than volume-controlled ventilation (VCV). But the data from previous studies showed controversial results about the gas exchange. Moreover, the comparison study between PCV and VCV with various inspiration : expiration time ratios (I : E ratios) is rare. So this study was performed to compare the respiratory mechanics and gas exchange between PCV and VCV with various I : E raitos. Methods : Nine patients receiving mechanical ventilation for respiratory failure were enrolled. They were ventilated by both PCV and VCV with various I : E ratios (1 : 2, 1 : 1.3 and 1.7 : 1). $FiO_2$, tidal volume, respiratory rate and external positive end-expiratory pressure (PEEP) were kept constant throughout the study. After 20 minutes of each ventilation mode, arterial blood gas, airway pressures, expired $CO_2$ were measured. Results : In both PCV and VCV, as the I : E ratio increased, the mean airway pressure was increased, and $PaCO_2$ and physiologic dead space fraction were decreased. But P(A-a)$O_2$ was not changed. In all three different I : E ratios, peak inspiratory pressure was lower during PCV, and mean airway pressure was higher during PCV. But $PaCO_2$ level, physiologic dead space fraction and P(A-a)$O_2$ were not different between PCV and VCV with three different I : E ratios. Conclusion : There was no difference in gas exchange between PCV and VCV under the same tidal volume, frequency and I : E ratio.

• Journal of Korean Classical Literature and Education
• /
• no.16
• /
• pp.273-296
• /
• 2008

The author analyzed the psychological factors which affected on the way of Mrs. Park in the became a virtuous woman and compared these psychological factors with a virtuous women in Samganghaengsildo based on the relationship between Mrs. Park in and Samganghaengsildo's the virtuous women volume. First of all, it's about the power of authority on women. The volume of Samganghaengsildo's virtuous women was about the group of women who were recognized as virtuous women by the king who had absolute power at the time period. The volume of Samganghaengsildo's virtuous women was very well known for women. This book had a huge impact on women since the government authority educated the women using this book. In addition, the incredible events which were written in Samganghaengsildo indicated that the behavior of virtue was the right thing to follow since even super power recognized it as a good thing to do and the woman might be punished when she didn't follow the behavior of virtue. Second, it was based on the similarity of circumstance and uncertainty for the future. Mrs. Park in showed similar behavioral patterns with a virtuous woman in Samganghaengsildo since she took her role model from the virtuous woman. When Mrs. Park lost her husband, she was not sure about her future and the volume of Samganghaengsildo pointed out that there was another world after the death and she would meet her husband again after the death. In addition, the incorrect information that she would feel better psychologically when she followed her dead husband instead of living herself. Third, it is about the resemblance of obsessive mind and self internalization. The examination of the record of Mrs. Park showed that Mrs. Park tried to internalize integrity, loyalty, and virtue of virtuous women in Samganghaengsildo and became herself like virtuous women. In addition, the woman's obsessive mindset remarkly reflected in Samganghaengsildo. For instance, Mrs. Park in held to the time of death of her husband and the writer who wrote about the behavior of Mrs. Park also emphasized that the time of death of Mrs. Park was closed to the time of the death of her husband. This explained that the obsessive mindset of women in the epic of virtue women could have influence on the women's mind who tried to show the similar behavior with a virtue woman and internalize it. Finally, the people of the day also were not free from it.