• Tuberculosis and Respiratory Diseases
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• v.45 no.5
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• pp.1022-1030
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• 1998

Background : In volume-controlled ventilation, the use of inspiratory pause increases the inspiratory time and thus increases mean airway pressure and improves ventilation. But under the same I : E ratio, the effects of inspiratory pause on mean airway pressure and gas exchange are not certain. Moreover, the effects may be different according to the resistance of respiratory system. So we studied the effects of inspiratory pause on airway pressure and gas exchange under the same I : E ratio in volume-controlled ventilation. Methods: Airway pressure and arterial blood gases were evaluated in 12 patients under volume-controlled mechanical ventilation with and without inspiratory pause time 5%. The I : E ratio of 1 : 3, $FiO_2$, tidal volume, respiratory rate, and PEEP were kept constant. Results: $PaCO_2$ with inspiratory pause was lower than without inspiratory pause ($38.6{\pm}7.4$ mmHg vs. $41.0{\pm}7.7$ mmHg. p<0.01). P(A-a)$O_2$ was not different between ventilation with and without inspiratory pause $185.3{\pm}86.5$ mmHg vs. $184.9{\pm}84.9$ mmHg, p=0.766). Mean airway pressure with inspiratory pause was higher than without inspiratory pause ($9.7{\pm}4.0\;cmH_2O$ vs. $8.8{\pm}4.0\;cmH_2O$, p<0.01). The resistance of respiratory system inversely correlated with the pressure difference between plateau pressure with pause and peak inspiratory pressure without pause (r=-0.777, p<0.l), but positively correlated with the pressure difference between peak inspiratory pressure with pause and peak inspiratory pressure without pause (r=0.811, p<0.01). Thus the amount of increase in mean airway pressure with pause positively correlated with the resistance of respiratory system (r=0.681, p<0.05). However, the change of mean airway pressure did not correlated with the change of $PaCO_2$. Conclusion: In volume-controlled ventilation under the same I : E ratio of 1 : 3, inspiratory pause time of 5% increases mean airway pressure and improves ventilation. Although the higher resistance of respiratory system, the more increased mean airway pressure, the increase in mean airway pressure did not correlated with the change in $PaCO_2$.

• Korean Chemical Engineering Research
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• v.44 no.4
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• pp.410-416
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• 2006

For highly efficient operation of a Bunsen process section in an iodine-sulfur thermochemical hydrogen production cycle using nuclear heat, the process characteristics of $H_2SO_4-HI-H_2-O-I_2$ mixture system for separating into two liquid phases ($H_2SO_4$-rich phase and $HI_x$-rich phase) and the distribution of $H_2O$ to each phase were investigated.The experiments for process variables were carried out in the temperature range, from 298 to 353 K, and in the $H_2SO_4/HI/H_2O/I_2$ molar ratio of 1/2/14~20/0.5~8.0. As the results, for the $SO_2-I_2-H_2O$ Bunsen reaction system, the ranges between the starting point and the saturation point for two liquid phases separation were determined by calculation. The best result for the minimization of impurities (HI and $I_2$ in $H_2SO_4$ phase and $H_2SO_4$ in $HI_x$ phase) in each phase was obtained in an optimum condition with the highest temperature of 353 K and the highest $I_2$ molar composition. In this condition, the $HI/H_2SO_4$ molar ratio in the $H_2SO_4$-rich phase and the $H_2SO_4/HI_x$ molar ratio in the $HI_x$-rich phase were 0.024 and 0.028, respectively. For the distribution of $H_2O$ to each phase, it is appeared that the affinity between $HI_x$ and $H_2O$ was more superior to that between $H_2SO_4$ and $H_2O$. The affinity between $HI_x$ and $H_2O$ was decreased with increasing temperature but increased with increasing $I_2$ molar composition.

• Journal of Environmental Health Sciences
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• v.46 no.5
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• pp.504-512
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• 2020

Objective: The purpose of this study was to evaluate the indoor to outdoor ratio (I/O ratio) of time activity patterns affecting PM_2.5 concentrations in homes in Korea through a simulation. Methods: The time activity patterns of homemakers were analyzed based on the 'Time-Use Survey' data of the National Statistical Office in 2014. From September 30 to October 2, 2019, the experimenter lived in multifamily housing located in Guro-gu, Seoul. The I/O ratio of PM_2.5 concentration was measured by installing sensor-based instruments. Results: The average indoor and outdoor PM_2.5 concentrations during the three days were 33.1±48.9 and 45.9±25.3 ㎍/㎥, respectively. The average I/O ratio was 0.75±0.60. The indoor concentration tended to increase when PM_2.5 source activity such cooking and cleaning was present and outdoor PM_2.5 was supplied through ventilation. Conclusions: This study could be used as basic data for estimating indoor PM_2.5 concentrations with personal activity pattern and weather conditions using outdoor concentrations.

• Journal of Conservation Science
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• v.29 no.3
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• pp.279-286
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• 2013

It is characterized and classified as the type of red brown glass beads to compare the chemical composition and manufacturing technique on the 141 samples in 12 sites of the Three Kingdom Period analyzed until now. It can be divided into three types according to the chemical composition of stabilizers(CaO & $Al_2O_3$) and soda raw materials(MgO & $K_2O$) on the red brown glass beads except one sample. Type I of high alumina glass is identified as the most common types that is 78.6 % of the distribution ratio at analytical samples and is excavated the most from ruin sites. In contrast, type II, 13.6 % of distribution ratio at analytical samples, is about 5 % CaO and $Al_2O_3$, MgO and $K_2O$ at around 1.5 % is similar to the composition of plant ash glass. Type III is that the content of CaO is higher than $Al_2O_3$ and the content of MgO and $K_2O$ is below 1.5 %. It is the same as the composition of natron glass and its share is the lowest as 7.9 %. Of these, type III is divided into two types according to the content of MgO and $K_2O$. It is identified that manufacturing technique of type I and II is drawing and type III is casting method with microscopic investigations. Type II and III is estimated that raw materials is different because is confirmed in the majority of ruins in spite of the fact that distribution ratio is very low. So, red brown glass beads distributed in Korea Peninsula are divided into three types of glass culture.

• Steel and Composite Structures
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• v.45 no.1
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• pp.23-38
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• 2022

This paper presents experimental and analytical studies of eccentrically loaded concrete-filled double steel (CFDST) and concrete-filled double skin tube (DCFST) columns having outer stainless steel tube. Eighteen CFDST and DCFST column specimens were manufactured and tested to examine the strength and load-deflection responses. In the study, the main parameters were concrete strength, load eccentricity, cross section and slenderness. The strengths, load-deflection diagrams and failure patterns of the columns were observed. In addition, the tested CFDST and DCFST columns were analyzed to attain the capacity and load versus lateral deflection responses. The obtained theoretical results were compared with the test results. A parametric study was also performed to research the effects of the ratio of eccentricity (e/H_o) slenderness ratio (L/r), H_o/t_o ratio, H_i/t_i ratio and the concrete compressive strength on the behavior of columns. In this work, the obtained results indicated that the ductility and capacity of columns were affected by cross section, concrete strength, steel strength, loading eccentricity and slenderness.

• Korean Journal of Remote Sensing
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• v.36 no.6_3
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• pp.1691-1710
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• 2020

We measured PM2.5 and PM10 (particulate matter less than 2.5 ㎛ and 10 ㎛ in diameter, respectively) simultaneously at 16 locations around an elementary school and classrooms in Busan and Pyeongtaek, South Korea. In this study, we compared the results of this field intensive with those in the literature (144 cases of 30 studies), focusing on I/O (Indoor/Outdoor) ratios. We also reviewed the results of previous studies, categorizing them into related sub-categories for indoor-activities, seasons, building-uses, and the surrounding environment. We conclude that indoor PM10 is affected more by indoor-sources (e.g., physical activities) than PM2.5 in the absence of combustion sources like smoking and cooking. Additionally, PM10 and PM2.5 likely have different indoor-outdoor infiltration efficiencies. Conclusively, PM10 in classrooms can be more sensitively affected by both indoor activities and ambient concentrations, and mechanical ventilation can be more efficient in reducing PM concentrations than natural ventilation.

• Electrical & Electronic Materials
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• v.7 no.4
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• pp.281-288
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• 1994

According to spread volume of B(BiPbCuO) layer, composition ratio and each stage of sintering process, we studied stability of high Tc superconductor phase and generation and growth movement of superconducting phase. The dual layer composed of SrCaCuO and BiPbCuO compound were prepared to develop the Bi-2223 superconductor[108K] through interaction and diffusion during sintering process. The dual layer samples were sintered at 830.deg. C for 0-210 hours. From the result, the optimum conditions were : spread volume(A:B=1:0.6), sintering time(210h) and composition ratio(A:S $r_{2}$C $a_{2}$C $u_{2}$- $O_{x}$, B:B $i_{1.9}$P $b_{0.5}$C $u_{3}$ $O_{y}$) at 830.deg. C.. C.C.C.

• Korean Journal of Materials Research
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• v.19 no.1
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• pp.33-36
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• 2009

Inorganic-organic composite thin-film-transistors (TFTs) of ZnO nanowire/Poly(3-hexylthiophene) (P3HT) were investigated by changing the nanowire densities inside the composites. Crystalline ZnO nanowires were synthesized via an aqueous solution method at a low temperature, and the nanowire densities inside the composites were controlled by changing the ultrasonifiaction time. The channel layers were prepared with composites by spin-coating at 2000 rpm, which was followed by annealing in a vacuum at $100^{\circ}C$ for 10 hours. Au/inorganic-organic composite layer/$SiO_2$ structures were fabricated and the mobility, $I_{on}/I_{off}$ ratio, and threshold voltage were then measured to analyze the electrical characteristics of the channel layer. Compared with a P3HT TFT, the electrical properties of TFT were found to be improved after increasing the nanowire density inside the composites. The mobility of the P3HT TFT was approximately $10^{-4}cm^2/V{\cdot}s$. However, the mobility of the ZnO nanowire/P3HT composite TFT was increased by two orders compared to that of the P3HT TFT. In terms of the $I_{on}/I_{off}$ ratio, the composite device showed a two-fold increase compared to that of the P3HT TFT.

• Journal of the Korean Graphic Arts Communication Society
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• v.15 no.2
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• pp.77-90
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• 1997

Positive type presensitized offset plate developer were blended by quantitative analysis method. The test had been proceeeded to check variation of developability, shelf life and tone reproduction by SiO2/Na2O ratio to PS plate developer, added glycerin, and sodium phosphate with glycerin. This study of tone reproduction had been tested 5 times to get accuracy by PS platesusing kodak CCG C-3, KMS. The test result of tone reproduction of presensitized offset plates can be summarized as follows ; major compositions in positive type plate developer were Na, Si, K and P, developability were increased by Sio2/NaO2 ratio in positive type plate developer. Shelf life can be kept by add glycerin to positive type plate developer. Tone reproduction were improved by sodium phosphate due to buffer action while shelf life can be kept by add glycerin in positive type plate developer.

• Journal of IKEEE
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• v.23 no.2
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• pp.375-379
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• 2019

$ZnO-SnO_2(ZTO)$ was deposited by RF magnetron sputtering using a ceramic target whose Zn atomic ratio to Sn is 2:1 as a target, and the crystal structure variation with thermal treats was investigated. Transparent thin film transistors (TTFT) were fabricated using the ZTO films as active layers. About 100 nm-thick $Si_3N_4$ film grown on 100 nm-thick $SiO_2$ film was adopted as gate dielectrics. The mobility, threshold voltage, $I_{on}/I_{off}$, and interface trap density were obtained from the transfer characteristics of ZTO TTFTs. The effects of substrate temperature, and post-annealing on the property variation of ZTO TTFT were analyzed.