• 한국수소및신에너지학회논문집
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• 제32권5호
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• pp.401-409
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• 2021

The combination of different concentrations of ZnSO₄ in acidic solution as electrolyte in Zn-air batteries was investigated by Zn symmetrical cell test, half-cell and full cell tests. Using 1 M ZnSO₄ + 0.05 M H₂SO₄ as electrolyte and MnO₂ as air cathode catalyst with Zn foil anode, this combination had a satisfactory performance with balance of electrochemical activity and stability. Its electrochemical activity was matched to or even better than the PtRu catalyst in different current density. And its cycle life was improved (more than 100 cycles stable) by suppressing the growth of zinc dendrites on anode obviously. This electrolyte overcame the shortcomings of alkaline electrolyte that are easy to react with CO₂ in the air, severely growth of Zn dendrites caused by uneven plating/stripping of Zn.

• 한국물환경학회지
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• 제38권4호
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• pp.171-176
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• 2022

Recently, an autotrophic single-stage nitrogen removal (ASSNR) process based on the anaerobic ammonium oxidation (ANAMMOX) reaction has been proven as an economical ammonia treatment. It is highly evident that double-layered gel beads are a promising alternative to the natural biofilm for ASSNR because of the high mechanical strength of poly(vinyl alcohol) (PVA)/alginate structure and efficient protection of ANAMMOX bacteria from dissolved oxygen (DO) due to the thick outer layer. However, the thick outer layer results in severe mass transport limitation and consequent lowered bacterial activity. Therefore, the effects of the thickness of the outer layer on the overall reaction rate were tested in the biofilm model using AQUASIM for ammonia-oxidizing bacteria (AOB), nitrite-oxidizing bacteria (NOB) and ANAMMOX bacteria. A thickness of 0.5~1.0 mm is preferred for the maximum total nitrogen (TN) removal. In addition, a DO of 0.5 mg/L resulted in the best total nitrogen removal. A higher DO induces NOB activity and consequent lower TN removal efficiency. The optimal density of AO B and NO B density was 1~10% for a 10% ANAMMOX bacterial in the double-layered PVA/alginate gel beads. The real effects of operating parameters of the thickness of the outer layer, DO and concentrations of biomass balance should be intensively investigated in the controlled experiments in batch and continuous modes.

• 운동영양학회지
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• 제24권3호
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• pp.7-12
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• 2020

[Purpose] This study was performed to investigate the acid-base and ion balance at rest and after exercise in healthy males under normoxia, moderate hypoxia, and severe hypoxia. [Methods] Ten healthy Korean males completed three different trials on different days, comprising exercise under normoxia (F_iO₂ = 20.9%, N trial), moderate hypoxia (F_iO₂ = 16.5%, MH trial), and severe hypoxia (F_iO₂ = 12.8%, SH trial). They undertook endurance exercise for 30 min on a cycle ergometer at the same relative exercise intensity equivalent to 80% maximal heart rate under all conditions. Capillary blood samples were obtained to determine acid-base and ion balance at rest and after exercise. [Results] Exercise-induced blood lactate elevations were significantly increased as hypoxic conditions became more severe; SH > MH > N trials (P = 0.003). After exercise, blood glucose levels were significantly higher in the SH trial than in the N and MH trials (P = 0.001). Capillary oxygen saturation (S_CO₂) levels were significantly lowered as hypoxic conditions became more severe; SH > MH > N trials (P < 0.001). The pH levels were significantly lower in the MH trial than that in the N trial (P = 0.010). Moreover, H_CO_3^- levels were significantly lower in the SH trial than in the N trial, with significant interaction (P = 0.003). There were no significant differences in blood Na⁺, K⁺, and Ca²⁺ levels between the trials. [Conclusion] MH and SH trials induced greater differences in glucose, lactate, S_CO₂, pH, and HCO_3^- levels in capillary blood compared to the N trial. Additionally, lactate, S_CO₂, and HCO_3^- levels showed greater changes in the SH trial than in the MH trial. However, there were no significant differences in Na⁺, K⁺, and Ca²⁺ levels in MH and SH trials compared to the N trial.

• 에너지공학
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• 제25권4호
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• pp.159-169
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• 2016

본 연구에서는 함산소기재 중 MTBE를 휘발유에 첨가하여 산소함량(0, 1.0, 2.3 및 2.7 wt %)의 변화에 따라 MPI 및 GDi 차량에서 배출되는 유해한 배출가스와 연비를 분석하였다. 국내 및 미국의 연비시험방법인 FTP-75 mode와 HWFET mode를 적용하였다. CO, NMHC, NOx 배출량은 산소함량의 변화에 따라 미미한 차이는 있었지만 상관관계는 없었다. FTP-75 mode에서 CO2 배출량은 산소함량의 변화에 따라 증감의 경향성은 없었다. 하지만 차량이 예열된 상태이고 고속 운전영역이 포함된 FTP-75 mode의 phase-3와 HWFET mode에서는 산소를 함유한 연료의 CO2 배출량이 적었다. 입자개수 배출량은 산소함량과 음의 상관관계를 보였으며 산소함량 2.3 wt %에서 가장 적었다. 카본발란스법에 의해 계산된 연비는 산소를 함유한 연료가 높았으며 2.3 wt %에서 가장 높았다.

• 대한한방내과학회지
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• 제25권2호
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• pp.277-287
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• 2004

Objective : Diabetes is a disease in which the body does not produce or properly use insulin. Etiological studies of diabetes and its complications showed that oxidative stress might playa major role. Therefore, many efforts have been made to regulate oxygen free radicals for treating diabetes and its complications. Because Jindangwon has been known to be effective in treatment of diabetes, the methanol extract of Jindangwon was tested for its effectiveness in reducing the oxidative stress induced by Streptozotocin. Methods : Jindangwon was washed, dried in the shade and crushed. The crushed Jindangwon was extracted 3 times, each time with 3 volumes of methyl alcohol at $60^{\circ}C$ for 24 hours. The extract was filtered and evaporated under reduced pressure using a rotary evaporator to yield 30.6 g. Jindangwon extract was oral-administered to the diabetic rats induced by streptozotocin 50 mg per 1 kg of body weight for 15 days. The efficacy of the Jindangwon extract was examined with regard to the enzymatic pathways involved in the oxygen free radical production and the glutathione balance. Results : he effects of the methanol extract of Jindangwon in streptozotocin-induced diabetics rats with regard to body weight, blood glucose level, hepatic lipid peroxide level, hepatic xanthine oxidase activity and type conversion rate, hepatic glutathione level, hepatic glutathione peroxidase activity, hepatic glutathione reductase activity, hepatic aldose reductase activity, and hepatic sorbitol dehydrogenase activity were favorable enough to suggest that it is a cure for diabetes and its complications. Conclusions :These results support Jindangwon as an effective reducing agent for oxidative stress in the tissues and organs by regulating the production of oxygen free radicals. Jindangwon, in particular, shows promising results for its use as a cure, or preventative medicine for diabetes and its complications by reducing oxidative stress in beta-cells of the pancreas.

• 대한한의학회지
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• 제27권1호
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• pp.91-103
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• 2006

Objectives : Etiological studies of diabetes and its complications showed that oxidative stress might play a major role. Therefore, many effects have been fried to regulate oxygen free radicals for treating diabetes and its complications. Because Holotrichia has been known to be effective for the treatment of diabetes, the methanol extract of Holotrichia was tested for its effectiveness in reducing the oxidative stress induced by streptozotocin. Methods : Holotrichia was washed, dried in the shade and crushed. The crushed Holotrichia was extracted 3 times, each time with 3 volumes of methyl alcohol at $60^{\circ}C$ for 24h. The extract was filtered and evaporated under a reduced pressure using a rotary evaporator to yield 17 g. Holotrichia extract was oral-administed to the diabetic rats induced by streptozotocin 50 mg per 1 kg of body weight for 20 days. The efficacy of the Holotrichia extract was examined with regard to the enzymatic pathways involved in the oxygen free radical production and the glutathione balance. Results : The Effects of the methanol extract of Holotrichia in streptozotocin-induced diabolic rats with regards to body weight, blood glucose level, hepatic lipid peroxide level, hepatic superoxide anion radical content. hepatic xanthine oxidase activity and type conversion rate, hepatic glutathione level, hepatic aldose reductase activity, and hepatic sorbitol dehydrogenase activity were shown to be good enough to cure and prevent the diabetes and its complications. Conclusions : These results indicated that Holotrichia might reduce the oxidative stress in the tissues and organs by regulating the production of oxygen free radicals. Especially, Holotrichia might prevent and cure the diabetes and its complications by reducing the oxidative stress in the ${\beta}$-cells of pancreas. Some suggestions on biophoton experiments were made.

• 대한한방내과학회지
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• 제27권4호
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• pp.811-821
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• 2006

Objectives : Diabetes is a disease in which the body does not produce or properly use insulin. Etiological studies of diabetes and its complications showed that oxidative stress might play a major role. Therefore, many methods have been tried to regulate oxygen free radicals for treating diabetes and its complications. Because Mori foliumhas been known to be effective for the treatment of diabetes, the methanol extract of Mori folium was tested for its effectiveness in reducing the oxidative stress induced by streptozotocin. Methods : The crushed Mori folium was extracted 3 times, each time with 3 volumes of methyl alcohol at $60^{\circ}C$ or 24 h. The extract was filtered and evaporated under reduced pressure using a rotary evaporator to yield 11.7 g. Mori folium extract was oral-administered to diabetic rats induced by streptozotocin at 100 mg per 1 kg of body weight for 20 days. The efficacy of the Mori foliumextract was examined with regard to the enzymatic pathways involved in oxygen free radical production and glutathione balance. Results : The effects of the Mori foliumin streptozotocin-induced diabetic rats with regards to body weight, blood glucose and insulin level, hepatic lipid peroxide level, hepatic glutathione level, hepatic glutathione S-transferase and glutathione peroxidase level, hepatic aldose reductase activity, and hepatic sorbitol dehydrogenase activity were shown to be good enough to cure and prevent diabetes and its complications. Conclusions : These results indicated that Mori folium might reduce oxidative stress in tissues and organs by regulating the production of oxygen free radicals. Especially Mori folium might prevent and cure diabetes and its complications by reducing oxidative stress in the ${\beta}-cells$ of the pancreas.

• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2001년도 Proceedings of 6th International Joint Symposium on Microeletronics and Packaging
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• pp.45-47
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• 2001

Due to pressure from threatened legislation in Europe, consumer and governmental pressure in Japan, and glob머 market considerations in the US, there is a rapidly growing interest in lead-free solderinger, Although the move to lead free soldering seems inevitable, many problems will arise in production assembly. It is generally acknowledged that the lead-free solders available offer a much s smaller process window than lead/tin, related mainly to the higher soldering temperatures which naturally result from increases of liquidus temperatures of at least 300 C. However, raising reflow temperatures from the current 220-2300 C to 250 2600 C will lead to problems with the boards and components as well as i increasing oxidation effects. There is a need to keep reflow temperatures low without reducing solderablity. Some results on benefits of inert atmospheres are discussed in this paper. For example, testing in a nitrogen atmosphere, with 300 ppm oxygen, by the N National Physical Laboratory (NPU has revealed clear benefits for ine$\pi$mg lead-free alloys, by restoring the solderability to lead/tin levels, by enabling lower soldering temperatures. However, there has been little testing over a range of oxygen levels in nitrogen and this is an important issue in determining n nitrogen supply and oven costs. Some results are reported here from work by NPL conducted for BOC in w which solderability was evaluated for tin기ead and tin/silver/copper eutectic a alloys in a wetting balance over a range of oxygen levels form 10 ppm to 21% ( (air). The studies confirm that acceptable wetting times occur in inert atmospheres a at soldering temperatures 20 to 300 C lower than are possible in air.

• 한국수소및신에너지학회논문집
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• 제27권2호
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• pp.201-210
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• 2016

To develop a pressurized chemical looping combustor, conceptual design of 0.5 MWth chemical looping combustor was performed by means of mass and energy balance calculations. Based on the conceptual design, reactivity of oxygen carrier and solid circulation rate were selected as key parameters. Sensitivity analysis of those key parameters were conducted with the change of oxygen carrier utilization percent from 5 to 50% and proper solid circulation rate and solid conversion rate to meet 98% of $CO_2$ selectivity were confirmed. Feasibility of 0.5 MWth pressurized chemical looping combustor was confirmed by experimental studies to find real solid circulation rate and $CO_2$ selectivity within the operating conditions based on the conceptual design. We could varied very wide range of solid circulation rate in two interconnected fluidized bed system. We also got enough $CO_2$ selectivity more than 98% in semi-continuous chemical looping combustor using OCN717 oxygen carrier. Consequently, feasibility of 0.5 MWth pressurized chemical looping combustor was confirmed.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2015-2020
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• 2007

Diesel is an excellent candidate fuel for fuel cell applications due to its high hydrogen density and well-established infrastructure. But, it is hard to guarantee desirable performance of diesel reformer because diesel reforming has several problems such as sulfur poisoning of catalyst and carbon deposition. We have been focusing on diesel autothermal reforming(ATR) for substantial period. It is reported that ATR of diesel has several technical advantages such as relatively high efficiency and fuel conversion compared to steam reforming(SR) and partial oxidation(POX). In this paper, we investigate characteristics of diesel reforming under various ratios of reactants(oxygen to carbon ratio, steam to carbon ratio) for improvement of reforming performances(high reforming efficiency, high fuel conversion, low carbon deposition). We also exhibit calculated heat balance of autothermal reformer at each condition to help thermal management of SOFC system.