• The Korean Journal of Malacology
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• v.24 no.3
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• pp.261-267
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• 2008

The tendency of metabolism in oyster, Crassostrea gigas, was investigated in relation to the water temperature and salinity. Oxygen consumption and ammonia excretion were measured and O:N ratio were calculated according to the water temperature from February 2007 to September 2008 and body size. The relationship between oxygen consumption and body weight has been examined in C. gigas. The weight-specific oxygen consumption rate (mg $O_2$/g/h) varied inversely with size. Oxygen consumption and ammonia excretion increased with an increase in water temperature. O:N ratio measured in this study ranged from 8 to 40 under ordinary sea water and the ratio was 8 at $25^{\circ}C$ and 16 at $10^{\circ}C$. This indicates that oyster mainly use the protein as the primary catabolic substrate during gametogenesis. Lower O:N ratio in winter suggests that oysters have to meet their energy demand by metabolizing protein to survive in stressful conditions such as low temperature and lack of sufficient food supply. This studies will provide the basic data for oyster culture farm in assessing the carrying capacity and sustainable management.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.1006-1011
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• 1991

In this paper, a neural network estimator which estimates the output of the wide range oxygen sensor is proposed, The neural network estimator is constructed to give the output of the wide range oxygen sensor from rpm, fuel injection time, throttle position, and output voltage of the exhaust gas oxygen sensor. And, using this estimator, PI controller for air-fuel ratio control is designed. Experiment results show that the proposed method gives good results for SONATA engine under light load and constant rpms.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.2
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• pp.47-54
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• 2012

An oxygen sensor installed in vehicle exhaust systems enables to measure the amount of oxygen in the exhaust gas, in which the measured data are collected and analyzed in ECU(Engine Control Unit). The oxygen sensor is exposed to the high speed exhaust gas at high temperature circumstance, so that protection caps are required not only to protect the susceptible measuring part, but also to provide the real time measurement without time delay. In this study, a new oxygen sensor with one protection cap was proposed, and the CFD analysis was carried out in order to compare the performance characteristics, such as flow speed and ratio of AOA(Age of Air), for the conventional and new oxygen sensor. The numerical results of CFD analysis provided the flow speed of 1.34m/s and the ratio of AOA of 3.43. The similar features obtained from the numerical results showed that the new oxygen sensor guarantees the same performance characteristics of the conventional ones.

• Journal of Environmental Health Sciences
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• v.21 no.2
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• pp.68-74
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• 1995

The optimum conditions was synthesized for the formation of Magnetite ($Fe_3O_4$) by air bubbling with the suspensions obtained by mixing Ferrous sulfate ($FeSO_4\cdot 7H_2O$) and Sodium Hydroxide (NaOH) solution in various values equivalent ratio($R=2NaOH/FeSO_4$) were studied. The changes of the structure were measured with XRD, $EM and BET. Equivalent ratio R: 0.65 was synthesized Goethite ($\alpha$-FeOOH), which becomes Maghemite ($\gamma=Fe_2O_3$) by dehydration, reduction and oxidation process. At the equivalent ratio over 1 (R>1), Magnetite ($Fe_3O_4$) was synthesized directly. The oxygen-deficient Magnetite ($Fe_3O_{4-\delta}$), which is obtained by flowing $H_2$ gas(100 ml/min) through the synthesis Magnetite at 350$\circ$C for 4 hr. By using it, was researched the decomposition reaction of $CO_2$. $CO_2$ was decomposed nearly 100% in 45 minutes by the oxygen-deficient Magnetite.

• Journal of the Korean Vacuum Society
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• v.19 no.3
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• pp.224-229
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• 2010

Indium oxide $(In_2O_3)$ thin films have been prepared on glass substrate by using radio-frequency reactive magnetron sputtering with changing the oxygen flow ratio. The substrate temperature was kept at a fixed value of $400^{\circ}C$, and the sputtering gas and reactive gas were supplied with argon and oxygen, respectively. The oxygen partial flow ratio was varied by controlling the amount of oxygen with respect to the total mixed gases, 10%, 20%, 30%, 40%, and 50%. The optical, electrical, and structural properties of the deposited thin films were investigated by using ultraviolet-visible-near infrared spectrophotometer, Hall measurement, and X-ray diffractometer and scanning electron microscopy. The $In_2O_3$ thin film deposited at 20% of oxygen flow ratio showed an average transmittance of 86% in the wavelength range of 430~1,100 nm, an electrical resistivity of $1.1{\times}10^{-1}{\Omega}cm$. The results show that the transparent conducting films with optimum conditions can be achieved by controlling the oxygen flow ratio.

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.3
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• pp.102-111
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• 1996

For the air-fuel ratio control in a fuel injection SI engine, the Jump-Ramp control algorithm has been widely adopted by using the on/off type oxygen sensor. But the Jump-Ramp control method has limitation on treating the frequency and amplitude of the air-fuel ratio oscillation. This study suggests another feedback control logic named modulated fuel feedback control, which has a concept of pre-tuned air-fuel ratio oscillation. In the modulation method, the oxygen sensor output is not treated as on/off signal but as analog signal for feedback. By using the modulation method, the frequency and the amplitude of air-fuel ratio oscillation can be adjustable to some extent for improving the conversion efficiency of the Three-Way Catalyst. The result shows that the performance of the modulation method is better than that Jump-Ramp control method in reducing the amplitude of the air-fuel ratio oscillation as well as in increasing the frequency of the air-fuel ratio oscillation.

• Journal of Powder Materials
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• v.28 no.6
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• pp.478-482
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• 2021

The effect of the process conditions of high-velocity oxygen fuel (HVOF) thermal spray coating on the porosity of the coating layer is investigated. HVOF coating layers are formed by depositing amorphous FeMoCrBC powder. Oxygen pressure varies from 126 to 146 psi and kerosene pressure from 110 to 130 psi. The Microstructural analysis confirms its porosity. Data analysis is performed using experimental data. The oxygen pressure-kerosene pressure ratio is found to be a key contributor to the porosity. An empirical model is proposed using linear regression analysis. The proposed model is then validated using additional test data. We confirm that the oxygen pressure-kerosene pressure ratio exponentially increases porosity. We present a porosity prediction model relationship for the oxygen pressure-kerosene pressure ratio.

• Journal of Energy Engineering
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• v.7 no.1
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• pp.7-16
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• 1998

Numerical computations were performed for the gasification of five different coals such as Lewis-Stockton bituminous, Utah bituminous. Illinois #6 bituminous, Usibelli sub-bituminous and Beulah-Zap lignite, to assess the effect of variation in oxygen to coal ratio and steam to coal ratio on reactive flow fields within an axisymmetric, entrained-flow gasifier. The concentrations of major products, CO and $H_2$, were calculated with varying oxygen to coal ratio(0.7~1.4) and steam to coal ratio. To verify the validity of predictions, the predicted and the measured values of CO and $H_2$ concentrations at the exit of the gasifier were compared for Roto coal. Reasonable agreement was obtained between the predicted and measured values. Predictions showed that the (CO+H_2$) concentration increased gradually to its maximum value with increasing oxygen-coal ratio, and CO concentration decreased, but $H_2$ concentration increased to some extent with increasing steam-coal ratio. When the oxygen-coal ratio was between 1.0 and 1.2, and the steam-coal ratio was between 0.3 and 0.4, high values of the cold-gas efficiency were obtained.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.9
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• pp.847-854
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• 2013

The objective of this study is to experimentally investigate the mixed flow and oxygen transfer characteristics of a horizontally injected aeration process using an annular nozzle ejector. The flow rate ratio, pressure ratio and ejector efficiency are calculated using the measured flow rate and pressure with the experimental parameters of the ejector pitch and primary flow rate. The visualization images of mixed flow issuing from the ejector are analyzed qualitatively, and the volumetric oxygen transfer coefficients are calculated using the measured dissolved oxygen concentration. The mixed flow behaves like a buoyancy jet or horizontal jet owing to the momentum of primary flow and air bubble size. The buoyancy force of the air bubble and the penetration of mixed flow are found to be important parameters for the oxygen transfer rate owing to the contact area and time of two phases.

• Journal of the Korean Society of Combustion
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• v.12 no.4
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• pp.14-21
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• 2007

In order to enhance combustion efficiency, oxygen-enriched combustion is used by increasing the oxygen ratio in the oxidizer. However, since the flame temperature increases, NOx formation in the furnace seriously increases for low oxygen enrichment ratio. In this case, reburning is a useful technology for reducing nitric oxide. In this research, experimental studies have been conducted to evaluate the hybrid effects of reburning/selective non-catalytic reaction (SNCR) and reburning/air staging on NOx formation and also to examine heat transfer characteristics in various oxygen-enriched LPG flames. Experiments were performed in flames stabilized by a co-flow swirl burner, which were mounted at the bottom of the furnace. Tests were conducted using LPG gas as main fuel and also as reburn fuel. The paper reported data on flue gas emissions, temperature distribution in furnace and various heat fluxes at the wall for a wide range of experimental conditions. Overall temperature in the furnace, heat fluxes to the wall and NOx generation were observed to increase by low level oxygen-enriched combustion, but due to its hybrid effects of reburning, SNCR and Air staging, NOx concentration in the exhaust have decreased considerably.