• 한국세라믹학회지
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• 제51권1호
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• pp.51-56
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• 2014

Mixed ionic and electronic conducting $K_2NiF_4$-type oxide, $Nd_{2-x}Sr_xNiO_{4+\delta}$ (x = 0, 0.4, 0.6) powders were synthesized by a solid-state reaction technique and solid oxide fuel cells consisting of a $Nd_{2-x}Sr_xNiO_{4+\delta}-GDC$ cathode, a Ni-YSZ anode and 8YSZ as an electrolyte were fabricated. The effect of strontium substitution for neodymium on the electrical and electrochemical properties was examined. The electrical conductivity increased with an increase in the Sr doping content, while it appears that the excess oxygen (${\delta}$) decreased. Sr doping into $Nd_2NiO_{4+\delta}$ resulted in an increase in the cathode polarization resistance and an decrease in the power density of the cell. These phenomena may be associated with the decreased amount of excess oxygen noted in the $Nd_{2-x}Sr_xNiO_{4+\delta}$ cathode.

• 운동영양학회지
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• 제25권1호
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• pp.35-41
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• 2021

[Purpose] This pilot study aimed to develop a regression model to estimate the excess post-exercise oxygen consumption (EPOC) of Korean adults using various easy-to-measure dependent variables. [Methods] The EPOC and dependent variables for its estimation (e.g., sex, age, height, weight, body mass index, fat-free mass [FFM], fat mass, % body fat, and heart rate_sum [HR_sum]) were measured in 75 healthy adults (31 males, 44 females). Statistical analysis was performed to develop an EPOC estimation regression model using the stepwise regression method. [Results] We confirmed that FFM and HR_sum were important variables in the EPOC regression models of various exercise types. The explanatory power and standard errors of estimates (SEE) for EPOC of each exercise type were as follows: the continuous exercise (CEx) regression model was 86.3% (R²) and 85.9% (adjusted R²), and the mean SEE was 11.73 kcal, interval exercise (IEx) regression model was 83.1% (R²) and 82.6% (adjusted R²), while the mean SEE was 13.68 kcal, and the accumulation of short-duration exercise (AEx) regression models was 91.3% (R²) and 91.0% (adjusted R²), while the mean SEE was 27.71 kcal. There was no significant difference between the measured EPOC using a metabolic gas analyzer and the predicted EPOC for each exercise type. [Conclusion] This pilot study developed a regression model to estimate EPOC in healthy Korean adults. The regression model was as follows: CEx = -37.128 + 1.003 × (FFM) + 0.016 × (HR_sum), IEx = -49.265 + 1.442 × (FFM) + 0.013 × (HR_sum), and AEx = -100.942 + 2.209 × (FFM) + 0.020 × (HR_sum).

• 공업화학
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• 제9권3호
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• pp.355-360
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• 1998

본 연구에서는 여러 귀금속 이온 교환 HZSM-5 촉매상에서 NO의 선택적 환원 반응 및 과잉 산소 존재 하에서 탄화수소 환원제를 첨가하지 않은 조건에서의 직접 분해 반응을 수행하여 NO 제거 활성을 비교 검토하였으며, Cu-HZSM-5 촉매의 활성과도 비교하였다. 사용한 촉매 중 Ru-HZSM-5 상에서 탄화수소 환원제 없이 $NO+O_2$반응을 수행한 결과 최대 45%의 NO에서 $N_2$로의 전환율을 얻을 수 있었으며 수증기의 첨가에 대해서도 상당한 저항성을 나타내었다. 이러한 Ru-HZSM-5의 높은 활성은 NO를 과잉 산소 존재 하에서 $NO_2$로 전환시키는 능력이 우수하기 때문이라고 생각된다. Ru-HZSM-5 촉매상에서 NO는 기상 탄화수소 환원제가 없는 과잉 산소 존재 하에서는 먼저 $NO_2$로 산화된 후 이어 $N_2$로 분해되는 반응 경로를 거치는 것으로 생각되며 촉매 표면에 흡착되는 $NO_2$는 이 반응의 일종의 중간 생성물이라 판단된다.

• 상하수도학회지
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• 제28권2호
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• pp.161-170
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• 2014

It is essential to decrease energy consumption and excess sludge to economically operate sewage treatment plant. This becomes more important along with a ban on sea dumping and exhaustion of resource. Therefore, many researchers have been study on energy consumption reduction and strategies for minimization of excess sludge production from the activated sludge process. The aeration cost account for a high proportion of maintenance cost because sufficient air is necessary to keep nitrifying bacteria activity of which the oxygen affinity is inferior to that of heterotrophic bacteria. Also, additional costs are incurred to stabilize excess sludge and decrease the volume of sludge. There were anoxic, aerobic, membrane, deairation and concentration zone in this MBR process. Continuous aeration was provided to prevent membrane fouling in membrane zone and intermittent aeration was provided in aerobic zone through ammonia sensor. So, there was the minimum oxygen to remove $NH_4-N$ below limited quantity that could be eliminated in membrane zone. As the result of this control, energy consumption of aeration system declined by between 10.4 % and 19.1 %. Besides, we could maintain high MLSS concentration in concentration zone and this induced the microorganisms to be in starved condition. Consequentially, the amount of excess sludge decrease by about 15 %.

• 운동영양학회지
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• 제16권2호
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• pp.113-122
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• 2012

This study assessed the amount of energy consumed and fat deposition after endurance training in order to review the effect of 4-week endurance exercise on resting metabolic rate of a mouse during and after exercise and the effect of exercise. A total of 19 seven-week-old ICR male mice were used as the study subject. Those mice were divided into sedentary group (Sed) and trained group (Tr) after a week of environment adaption. The Tr group was trained with endurance exercise five times a week for four weeks. Weight and the amount of food intake were daily weighed and resting metabolic rate and metabolic rate after exercise were assessed before starting exercise and on the fourth week after training. Metabolic rate during exercise were measured four weeks after training. At the end of breeding period, statistically significant difference was shown in weights of trained and sedentary groups (p < 0.05). During a resting period, no significant difference was shown in oxygen intake, respiratory exchange ratio, and the amount of carbohydrate and fat oxidized. Moreover, no significant difference was shown in excess post-exercise oxygen consumption (EPOC) of an hour period after training. In contrast, the maximal oxygen uptake (VO₂ max) was approximately 11.1% higher in trained group after training compare to before. However, there was no significant difference in respiratory exchange ratio and carbohydrate and fat oxidization. During exercise, oxygen uptake, carbon dioxide production, and respiratory exchange ratio in energy metabolism during exercise showed no significant difference. However, significant difference was exhibited in the amount of fat oxidized in both groups. Summing up those results, endurance exercise could be concluded to be effective in weight control. However, weight loss is thought to be resulted from increase in fat oxidization during exercise unlike the conclusion made from previous studies where weight loss is prominently influenced by energy metabolism during a resting period and increased fat oxidation during post-exercise recovery. All experimental procedures were carried out at the Animal Experiment Research Center of Konkuk University. This study was conducted in accordance with the ethical guidelines of the Konkuk University Institutional Animal Care and Use Committee.

• 한국전기전자재료학회논문지
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• 제37권3호
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• pp.231-240
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• 2024

Titanium dioxide (TiO₂) holds significant scientific and technological relevance as a key photocatalyst and resistive random-access memory, demonstrating unique physicochemical properties and serving as an n-type semiconductor. Understanding the density and arrangement of oxygen vacancies (VOs) is crucial for tailoring TiO₂'s properties to diverse technological needs, driving increased interest in exploring oxygen vacancy complexes and superstructures. In this mini review, we summarize the recent understandings of the fundamental properties of oxygen vacancies in bulk rutile (R-TiO₂) and anatase (A-TiO₂) based on DFT and beyond method. We specifically focus on the excess electrons and their spatial arrangement of disordered single VO in bulk R and A-TiO₂, aligned with the experimental findings. We also highlight the theoretical works on investigating the geometries and stabilities of ordered VOs complexes in bulk TiO₂. This comprehensive review provides insights into the fundamental properties of excess electrons in reduced TiO₂, offering valuable perspectives for future research and technological advancements in TiO₂-based devices.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.353-356
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• 2002

Planar laser induced fluorescence(PLIF) has been widely used to obtain two dimensional fuel distribution. Preliminary investigation was performed to measure quantitative air excess ratio distribution in an engine fueled with LPG. It is known that fluorescence signal from acetone as a fluorescent tracer is less sensitive to oxygen quenching than other dopants. Acetone was excited by KrF excimer laser (248nm) and its fluorescence image was acquired by ICCD camera with a cut-of filter to suppress Mie scattering from the laser light. For the purpose of quantifying PLIF signal, an image processing method including the correction of laser sheet beam profile was suggested. Raw images were divided by each intensity of laser energy and profile of laser sheet beam. Inhomogeneous fluorescence images scaled with the reference data, which was taken by a calibration process, were converted to air excess ratio distribution. This investigation showed instantaneous quantitative measurement of planar air excess ratio distribution for gaseous fuel.

• Journal of Nutrition and Health
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• 제9권4호
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• pp.54-58
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• 1976

Vitamin C의 변화는 식품의 가치를 판단하는데 중요한 인자가 된다. 이의 변화는 산소의 존재하에서 일차반응 속도로 분해된다고 알려져 있다. 그러나 제한된 량의 산소 속에서는 이차반응 내지 일차반응으로 설명되기도 한다. 이에 제한된 산소속에서 철, 구리 이온의 존재하에서 관찰한 바 용존산소와는 크게 관계없이 일차 반응속도로 분해되었고 이때 빛의 조사는 촉진적인 인자였었다.

• The Korean Journal of Ceramics
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• 제4권2호
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• pp.68-71
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• 1998

The effect of Mn and Nb additions on the electrical properties of BaTiO$_3$ has been studied by means of equilibrium electrical conductivity as a function of temperature, oxygen partial pressure(Po$_2$) and composition. If the manganese ion is added to the normal Ti site, i.e. BaTi$_{1-x}Mn_xO_{\delta-6}$, the equilibrium conductivity shows strong evidence of acceptor-doped behavior. The conductivity minimum, corresponding to the transition from oxygen excess, p-type behavior to oxygen deficient, n-type behavior with decreasing Po$_2$, is displaced to lower Po$_2$ and is broadened and flattened. The partial replacement of Mn ion with Nb decreases the acceptor-doped effect and the total replacement exhibits a typical donor-doped behavior. It was confirmed that unlike undoped or other acceptor-doped behavior. It was confirmed that unlike undoped or other acceptor-doped samples, for the p-type region, the electrical conductivity follows the 1/6th power dependence of oxygen partial pressure.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2012년도 제44회 KOSCO SYMPOSIUM 초록집
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• pp.43-46
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• 2012

The oxygen concentration of primary oxidizer is decided under 10% due to flammable risk. It can be a spontaneous combustion inside burner or tube if the excess oxygen is added to primary oxidizer in Oxy-PC burner. In this case, the rest oxygen which can not be injected to primary oxidizer should be injected to another port. If added it to a second oxidizer, the ignition is unstable at outlet of burner. Accordingly an extra lancing port is needed to insert into the burner unlike other common air mode. And the flame formation and combustion characteristic differ from lancing port position. Therefore we observed flame formation which has stable combustion characteristic according to the shape and position of lancing port.