• Journal of Biomedical Engineering Research
• /
• v.21 no.3 s.61
• /
• pp.311-320
• /
• 2000

In this paper a newly designed oxygenator module was used to perform the experiments for pressure drop and oxygen transport in order to evaluate the efficiency of the artificial lung. Also, distilled water. sodium sulfite solutions used in this experiment were evaluated for the performance of other artificial lungs. Substituted bloods have many advantages over whole blood in studying pressure drop and oxygen uptake. They are relatively inexpensive, and require fewer variables to be controlled. Furthermore, deoxygenation is not necessary when those solutions are used. In addition to these advantages. assays and interpretation of the experimental results are relatively easy. In the case of using the sodium sulfite solution having the same oxygen partial pressure as whole blood. the oxygen transfer rate of the sodium sulfite solution was basically same as that of whole blood. It was concluded in evaluating the function of artificial lungs that the sodium sulfite solution was suited for measuring oxygen transfer rate. In our module, artificial blood was flowed into the outside of hollow fiber membrane. The artificial lung created in this experiment showed that pressure drop was reduced to $1/3\~1/6$ of that compared to the inside-flow case.

• 한국생물공학회:학술대회논문집
• /
• 2000.04a
• /
• pp.406-409
• /
• 2000

For the effective treatment of dye-processing wastewater, JLR(Jet-Loop Reactor) with active carbon supports were investigated. BOD removal efficiency was found as 99% when influent BOD concentration of dye-processing wastewater was 400 mg/L. $COD_{Mn}$ of effluent removal efficiencies were found as 86${\sim}$ 89% when these of activated sludge reactor were 62${\sim}$72%. Also, color removal efficiencies were found as 84${\sim}$87% when these of activated sludge reactor were 72%${\sim}$77%. After JLR with active carbon supports had been used, all of the $COD_{Mn}$, $COD_{Cr}$ and color removal efficiencies Increased when chemical precipitation was done. Consequently, JLR with active carbon supports was proved to be more excellent than the activated sludge reactor.

• The KSFM Journal of Fluid Machinery
• /
• v.8 no.5 s.32
• /
• pp.7-12
• /
• 2005

Experimental study was conducted to increase the oxygen transfer efficiency of air diffusers in clean water. By measuring the bubble size from the bubbly two-phase flow visualization with several air diffusers, the size of air bubbles near the top surface of aeration tank seems to be independent on the diffuser types. Considering design parameters for the better break-up of larger bubbles around the air diffusers, advanced conceptual air diffusers using nozzle-type throat showing the higher oxygen transfer efficiencies were made.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.41 no.4
• /
• pp.257-268
• /
• 2017

This paper proposes an efficient two-dimensional simulation model for solid oxide fuel cells (SOFCs) based on the electrochemical effectiveness model. The effectiveness model is known to accurately predict the current generation performance of SOFC electrodes, by considering the complex reaction/transport processes that occur within thin active functional layers near the electrolyte. After validation tests, the two-dimensional simulation model was used to calculate the distribution of current density and oxygen concentration transverse to the flow channel in anode-supported SOFCs, with which the oxygen depletion characteristics were investigated in detail. In addition, simulations were also conducted to determine the minimum number of grids required in the transverse direction to efficiently obtain accurate results.

• Journal of the Korean Electrochemical Society
• /
• v.15 no.2
• /
• pp.83-89
• /
• 2012

We investigate the electrocatalytic activities for oxygen reduction at nanoporous gold (NPG) surfaces fabricated by selective dissolution of Ag from electrodeposited Ag-Au layers on electrode surfaces. The structure of NPG was controlled by changing the concentration ratios of precursor metal complexes during the electrodeposition of Ag-Au layers and the corresponding surface morphology and surface area was examined. NPG structures with Ag/Au ratio of 2.0 exhibited the highest electrocatalytic activity for oxygen reduction, where the nanoporous structure plays a key role, but the surface area does not affect on the electrocatalytic activity. The mechanism of electroreduction of oxygen was investigated by rotating disk electrode techniques. In acidic media, oxygen was first reduced to hydrogen peroxide followed by further reduction to water through 2-step 4-electron mechanism, whereas the oxygen was reduced directly to water by 4-electron mechanism in basic media.

• Korean Chemical Engineering Research
• /
• v.54 no.3
• /
• pp.394-403
• /
• 2016

$H_2$ production by chemical looping is an efficient method to convert hydrocarbon fuel into hydrogen with the simultaneous capture of concentrated $CO_2$. This process involves the use of an iron based oxygen carrier that transfers pure oxygen from oxidizing gases to fuels by alternating reduction and oxidation (redox) reactions. The enhanced reactivities of copper oxide doped iron-based oxygen carrier were reported, however, the fundamental understandings on the interaction between $Fe_2O_3$ and CuO are still lacking. In this study, we studied the effect of dopant of CuO to $Fe_2O_3/ZrO_2$ particle on the morphological changes and the associated reactivity using various methods such as SEM/EDX, XRD, BET, TPR, XPS, and TGA. It was found that copper oxide acted as a chemical promoter that change chemical environment in the iron based oxygen carrier as well as a structural promoter which inhibit the agglomeration. The enhanced reduction reactivity was mainly ascribed to the increase in concentration of $Fe^{2+}$ on the surface, resulting in formation of charge imbalance and oxygen vacancies. The CuO doped $Fe_2O_3/ZrO_2$ particle also showed the improved reactivity in the steam oxidation compared to $Fe_2O_3/ZrO_2$ particle probably due to acting as a structural promoter inhibiting the agglomeration of iron species.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.3
• /
• pp.420-426
• /
• 2020

In this study, an assistive device for BVM (Bag Valve Mask) was developed. When emergencies occur, rescuers must perform artificial respiration within four minutes utilizing suitable BVM. If not, the patient can suffer serious damage within their brain and body systems. The rescuer must execute artificial respiration until the patient arrives at the hospital. In the process of artificial respiration, the rescuer can feel fatigued in their forearm muscles, particularly those who may have smaller hands or weaker muscle strength. Many products have been developed to solve these problems, but these products are difficult to market and commercialize because of their volume, size, and difficulty of use. In this paper, the BVM assistive device that has been previously manufactured was improved, and an attempt was made to devise a new method that reduces the burden on the user. The BVM assistive device can be divided into three-parts: a head part for compressing the air bag, which can control the amount of air; the body part for coupling with BVM; and finally, the handle that can rotate for better use on various postures of patients. Throughout the experiment, the assistive device could inject an equal amount of air into the patients. As a result, the rescuer could feel less fatigue and inject a suitable amount of air to emergency patients during artificial respiration.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.36 no.3
• /
• pp.175-185
• /
• 2000

This paper described on a basic study to organize fishing vessel control system in order to control efficiently fishing vessel in Korean offshore. It was digitalized ARPA image on the fishing processing of a fleet of purse seiner in conducting fishing operation at Cheju offshore in Korea as a digital camera and then simulated by used VTMS. Futhermore, it was investigated on the application of FVTMS which can control efficiently fishing vessels in fishing ground. The results obtained were as follows ; (1) It was taken 16 minutes and 35 minutes to casting and hauling net in fishing processing respectively. The length of rope pulled by scout boat was 200m, tactical diameter in casting net was 340.8m, turning speed was 6kts as well. (2) The processing of casting and hauling net was moved to SW, NE as results of simulation when the current direction and speed set into NE, 2kts and SW, 2kts respectively. Such as these results suggest that can predict to control the fishing vessel previously with information of fishing ground, fishery and ship's maneuvering, etc. (3) The control range of VTMS radar used in simulation was about 16 miles. Although converting from a radar of the control vessel to another one, it was continuously acquired for the vector and the target data. The optimum control position could be determined by measuring and analyzing to distance and direction between the control vessel and the fleet of fishing vessel. (4) The FVTMS(fishing vessel traffic management services) model was suggested that fishing vessels received fishing conditions and safety navigation information can operate safely and efficiently.

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

• KSBB Journal
• /
• v.24 no.3
• /
• pp.303-311
• /
• 2009

A scaling up study for the exopolysaccharide (EPS) production by submerged culture of Ganoderma lucidum was carried out in jar fermenter systems (2.6, 20 and 75 L) under bi-staged pH process. Profiles of dissolved oxygen (DO) and volumetric coefficient of oxygen transfer ($k_La$) as a function of operating variables (agitation speed and aeration rate) was investigated, and a correlation between $k_La$ and operating variables was analysed statistically. Under bi-staged pH process, no limitation of DO was observed at agitation speeds tested in the range of 200 and 600 rpm, and the highest EPS production was obtained at the level of DO of $40{\sim}80%$. From the regression analysis, the relation between $k_La$, gas velocity (Vs), stirrer speed (N) and impeller diameter (Di) could be expressed as : $$k_La=0.555{\times}Vs^{0.42}{\times}(N^3{\times}Di^2)^{0.33}\;(R^2=0.925,\;p<0.05)$$ It was found that under 2.6 L jar fermenter, the optimum agitation speed and aeration rate was 400 rpm and 1 vvm, respectively, obtaining the EPS production of 15.43 g/L. Under the submerged cultivation of G. lucidum in jar fermenters of $2.6{\sim}75\;L$, the similar EPS yields at each fermenter were achieved during scaling up based on $k_La$, and $k_La$ value for maximum EPS production was $85.4{\pm}26.70\;h^{-1}$.