• 공업화학
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• 제10권3호
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• pp.415-418
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• 1999

튜브식 양극판과 겔전해액을 사용한 VRLA (valve regulated Iead-acid) 전지에 있어서 양극 활물질 (active material)의 충전 밀도에 따른 충 방전 싸이클 특성을 고찰하였다. VRLA전지에 사용된 양극 활물질의 밀도는 각각 3.2g/mL, 3.4g/mL 및 3.6g/ml 이었다. VRLA전지는 IU 방식 ($I_{max}=0.2C_{10}/10$, 상한 전압 2.40 v/cell)의 충전과, D.O.D 100%/C5의 방전 방법으로 충 방전 싸이클 수명 시험을 실시하였다. 시험은 $25{\pm}1^{\circ}C$의 항온항습기에서 실행하였다. 시험 결과 활물질 밀도별 VRLA전지의 초기 용량은 밀도와 무관하였다. 즉 3.4g/mL에서 가장 우수하였고, 3.6g/mL에서 가장 낮았다. 충 방전 싸이클에서의 특성은 3.6g/mL인 전지는 3.4g/mL와 거의 유사하였고, 3.2g/mL보다는 크게 우수하였다. 또한 VRLA 전지의 수분고갈 및 열화는 양극 활물질의 충전 밀도가 높을수록 적었다. 이상으로 충 방전 싸이클용 VRLA전지의 양극 활물질의 밀도는 3.4~3.6g/mL이 적절한 것으로 판단되었다.

• 생물환경조절학회지
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• 제17권4호
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• pp.319-324
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• 2008

우리나라 수출 작물로 가장 큰 비중을 차지하는 파프리카의 두 품종을 성숙 정도와 저장 조건을 달리하여 저장성을 비교하였다. 국내에서 많이 재배되는 'Special'과 'Fiesta' 두 품종을 수경재배하여 미숙과와 완숙과 상태로 수확한 후 무공 필름과 유공 필름으로 포장하여 $4^{\circ}C$와 $9^{\circ}C$에 저장하였다. 가장 긴 저장 수명을 보인 저장 조건을 $4^{\circ}C$에 포장 내 5%의 이산화탄소와 10%의 산소 농도를 보인 무공처리였다. 무공 처리의 경우 저장온도, 품종, 숙기정도에 관계없이 $3{\sim}9{\mu}l/l$ 에틸렌 농도를 보였으나 경도와 생체중 유지에 효과적이었으며 유공처리와 비교해서 부패율에도 차이가 크지 않았다. 50% 착색된 반숙과의 과피색은 $9^{\circ}C$와 무공 필름 처리에서 많이 착색되었으나, 완숙과 수준까지 진전되지는 못하였다. $4^{\circ}C$에서 20일간 저장한 후 상온에서 3일간 정치한 완숙 'Special'의 저온장해 정도를 전해질 용출량과 호흡 속도로 비교한 결과, 무공필름 포장에서 가장 효과적으로 억제되었다. 따라서 파프리카의 장기 유통 및 저장을 위해서는 적절한 무공 필름 포장과 저온장해가 발생하지 않는 범위의 저장장이 필요하리라 생각된다.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• 제25권1호
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• pp.79-86
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• 2022

Purpose: To determine the effect of zinc deficiency on fecal protein, electrolyte, and short-chain fatty acid levels in both heat-stable (ST) and heat-labile (LT) enterotoxigenic Escherichia coli (ETEC)-induced diarrhea in rats. Methods: Albino rats, weighing 100 to 150 g, were divided into 2 groups, with 15 animals each: non-zinc and zinc-deficient. These two groups were sub-divided into three sub-groups with five rats each: control (saline); LT-ETEC; and ST-ETEC. Sodium phytate (30 mmol/L) was added to the animals' water to induce zinc deficiency, while diarrhea was induced using 5×10⁹ ETEC cells/mL. Fecal protein levels were estimated using the Bradford method, while sodium and potassium levels were determined using atomic absorption spectrophotometry. Short-chain fatty acids were measured using gas chromatography-mass spectrometry. Results: Among the non-zinc and zinc-deficient groups, there were significant increases (p=0.04), (p=0.03) in fecal protein concentrations (mg/mL) in the LT-ETEC- (4.50±0.33), (6.50±0.26) and ST-ETEC- (3.85±0.19), (5.98±0.32) induced groups compared to the control groups (2.60±0.52), (3.50±0.11) respectively. Fecal sodium and potassium levels (mg/L) were significantly (p=0.029) increased in non-zinc-deficient rats induced with LT-ETEC (9.35±0.95, 1.05±0.48), and ST-ETEC (9.96±1.02, 1.21±0.45) compared with the control group (8.07±0.44, 0.47±0.17) but the increase were not statistically significant (p=0.059) in the zinc deficient rat groups. Fecal acetate and propionate levels (mg/g) significantly (p=0.032) increased when induced with LT-ETEC and ST-ETEC in non-zinc and zinc-deficient groups compared with the control groups. Conclusion: Zinc deficiency among rats with ETEC-induced diarrhea elevated fecal protein loss but may not have an effect on fecal sodium, potassium and short-chain fatty acid levels.

• 한국수소및신에너지학회논문집
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• 제16권1호
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• pp.40-48
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• 2005

Until recently, only perfluorinated ionomer membrane such as Nation and Aciflex practically could be successfully used in water splitting. However, these membrane are limited by high cost and loss of membrane performance such as proton conductivity at elevated temperature above 80$^{\circ}C$. The sulfonated aromatic polymers such as PEEK and PSf, polyimides, and polybenzimidazoles are expected to have lower production cost as well as satisfactory chemical and electrochemical properties. HPAs and sulfonated polymers could have a significant influence on water electrolysis performance at elevated temperatures above 80$^{\circ}C$, but these phenomena have received relatively little attention until now. Therefore, it would be desirable to investigate the interrelation between the HPA and sulfonated polymer, such as SPEEK. The SPEEK membrane were prepared by the sulfonation of PEEK, and HPA was blended with SPEEK to increase the mechanical strength and electrochemical characteristics. As a results, electrochemical characteristics such as proton conductivity and ion exchange capacity were improved with the addion of 0.5 g HPA. And the properties of polymer electrolyte, SPEEK/HPA were better than Nation membrane at elevated temperature above 80$^{\circ}C$.

• 대한화학회지
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• 제39권8호
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• pp.611-616
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• 1995

살리실알데히드 옥심, o-바닐린 옥심, 2-히드록시-4-메톡시벤즈알데히드 옥심, 2-히드록시-5-메톡시벤즈알데히드 옥심 및 5-니트로벤즈알데히드 옥심의 옥소바나듐(IV)착물들을 합성하고, 착물들의 특성을 원소분석, 전기전도도 측정, 적외선 분광법, 전자 분광법, 질량 분석법, 및 열분석으로 조사하였다. 원소분석의 결과는 이론 값과 실험 값이 일치하였다. 착물들은 DMF 용액에서 비전해질이었다. 바나듐(IV)과 말단 산소사이의 특성 신축진동은 $980{\pm}20\;cm^{-1}$의 영역에서 강하게 나타났다.모든 착물은 가시영역에서 2개의 결정장전이와 적외선 영역에서 2개의 전하이동 전이가 일어났다. 질량분석 결과로서 $VO(sal)_2$와 $VO(van)_2$에서는 분자량에 해당하는 1:2(금속:리간드) 착물의 이온(I)과 착물의 이온(I)에서 한리간드가 분해한 1:1(금속:리간드) 조성의 토막 이온(II)을 확인할 수 있었다. 시차열분석 결과에 의하면 열분해에 따른 흡열 봉우리가 나타났다.

• 대한한방부인과학회지
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• 제19권4호
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• pp.279-286
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• 2006

Purpose : The purpose of this study is to report the effect of oriental treatments to hyperemesis gravidarum in disturbed liver function. Methods : Hyperemesis gravidarum is a severe and intractable form of nausea and vomiting in pregnancy. It is a diagnosis of exclusion and may result in weight loss; nutritional deficiencies; and abnormalities in fluids, electrolyte levels, and acid-base balance. The peak incidence is at 4, 8-16 weeks of pregnancy. Interestingly, nausea and vomiting of pregnancy is generally associated with a lower rate of miscarriage. However disturbed diver dunction with Hyperemesis gravidarium is rare very and dangerous. Traditionally, oriental medical therapy has been used to patients with hyperemesis gravidarum and showed effective result. We treated 1 patient who had hyperemesis gravidarum in disturbed diver dunction at Se-Myung university Oriental Hospital in affiliation by Herbal medication, acupuncture and moxa therapy and got good result from them. Results : As a result, symptoms are remarkably alleviated and liver function test are improved. Conclusion : Therefore we would like to report that it is effective to cure the hyperemesis gravidarum in disturbed liver function through the herb-medication and acupuncture treatment.

• 한국세라믹학회지
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• 제39권1호
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• pp.86-91
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• 2002

고체 산화물 연료전지(Solid Oxide Fuel Cell; SOFC)는 무공해 청정에너지원으로서 기존의 발전방식을 대체할 차세대 에너지원으로 각광받고 있다. 고체산화물 연료전지의 구성요소는 크게 음극(anode), 양극(cathode), 전해질(electolyte)로 나뉘어 지는데 그 중 음극은 전극으로서의 역할은 물론 음극지지형인 경우 지지체 역할가지 수행해야 하기 때문에 아주 다양한 특성이 요구되어지고 있다. 그 중에서도 연료전지 성능의 최대 감쇄요인으로 지적되고 있는 분극저항을 줄이기 위해서는 높은 전기전도도와 높은 가스투과도가 요구되고있다. 본 연구에서는 음극 제조과정 중 첨가하는 기공 전구체의 종류에 따라 기판의 기공구조가 어떻게 바뀌는지 또 그로 인해 기판의 미세구조 및 전기전도도가 어떠한 영향을 받는지 관찰하였다. 결과 음극기판의 미세구조 및 전기전도도는 기공전구체의 종류에 따라 크게 달라졌으며 특히 이방성을 가지는 기공전구체의 사용은 전도성상의 단락 및 비효율적인 기공의 양산을 가져와 결과적으로 연료전지 성능을 악화시킬 것으로 예상된다.

• 한국수소및신에너지학회논문집
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• 제13권4호
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• pp.259-269
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• 2002

A battery based on the lithium/elemental sulfur redox couple has the advantage of high theoretical specific capacity of 1,675 mAh/g-sulfur. However, Li/S battery has bad cyclic durability at room temperature due to sulfur active material loss resulting from lithium polysulfide dissolution. To improve the cycle life of Li/S battery, PEGDME (Poly(ethylene glycol) dimethyl ether) 500 containing 1M LiTFSI salt which has high viscosity was used as electrolyte to retard the polysulfide dissolution and nano-sized $Mg_{0.6}Ni_{0.4}O$ was added to sulfur cathode as additive to adsorb soluble polysulfide within sulfur cathode. From experimental results, the improvement of the capacity and cycle life of Li/S battery was observed( maximum discharge capacity : 1,185 mAh/g-sulfur, C50/C1 = 85 % ). Through the charge-discharge test, we knew that PEGDME 500 played a role of preventing incomplete charge-discharge $behavior^{1,2)$. And then, in sulfur dissolution analysis and rate capability test, we first confirmed that nano-sized $Mg_{0.6}Ni_{0.4}O$ had polysulfide adsorbing effect and catalytic effect of promoting the Li/S redox reaction. In addition, from BET surface area analysis, we also verified that it played the part of increasing the porosity of sulfur cathode.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 춘계학술대회 논문집
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• pp.288-294
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• 2009

Various polymer electrolyte membrane fuel cell (PEMFC) startup procedures were tested to explore possible techniques for reducing performance decay and improving durability during repeated startup-shutdown cycles. The effects of applying a dummy load, which prevents cell reversal by consuming the air at the cathode, on the degradation of a membrane electrode assembly (MEA) were investigated via single cell experiments. The electrochemical results showed that application of a dummy load during the startup procedure significantly reduced the performance decay, the decrease in the electrochemically active surface area (EAS), and the increase in the charge transfer resistance ($R_{ct}$), which resulted in a dramatic improvement in durability. After 1200 startup-shutdown cycles, post-mortem analyses were carried out to investigate the degradation mechanisms via various physicochemical methods including FESEM, an on-line $CO_2$ analysis, EPMA, XRD, FETEM, SAED, FTIR. After 1200 startup-shutdown cycles, severe Pt particle sintering/agglomeration/dissolution and carbon corrosion were observed at the cathode catalyst layer when starting up a PEMFC without a dummy load, which significantly contributed to a loss of Pt surface area, and thus to cell performance degradation. However, applying a dummy load during the startup procedure remarkably mitigated such severe degradations, and should be used to increase the durability of MEAs in PEMFCs. Our results suggest that starting up PEMFCs while applying a dummy load is an effective method for mitigating performance degradation caused by reverse current under a repetition of unprotected startup cycles.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 춘계학술대회
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• pp.250-253
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• 2007

An evaporated Ti/Pd/Ag contact system is most widely used to make high-efficiency silicon solar cells, however, the system is not cost effective due to expensive materials and vacuum techniques. Commercial solar cells with screen-printed contacts formed by using Ag paste suffer from a low fill factor and a high shading loss because of high contact resistance and low aspect ratio. Low-cost Ni and Cu metal contacts have been formed by using electroless plating and electroplating techniques to replace the Ti/Pd/Ag and screen-printed Ag contacts. Ni/Cu alloy is plated on a silicon substrate by electro-deposition of the alloy from an acetate electrolyte solution, and nickel-silicide formation at the interface between the silicon and the nickel enhances stability and reduces the contact resistance. It was, therefore, found that nickel-silicide was suitable for high-efficiency solar cell applications. The Ni contact was formed on the front grid pattern by electroless plating followed by anneal ing at $380{\sim}400^{\circ}C$ for $15{\sim}30$ min at $N_{2}$ gas to allow formation of a nickel-silicide in a tube furnace or a rapid thermal processing(RTP) chamber because nickel is transformed to NiSi at $380{\sim}400^{\circ}C$. The Ni plating solution is composed of a mixture of $NiCl_{2}$ as a main nickel source. Cu was electroplated on the Ni layer by using a light induced plating method. The Cu electroplating solution was made up of a commercially available acid sulfate bath and additives to reduce the stress of the copper layer. The Ni/Cu contact was found to be well suited for high-efficiency solar cells and was successfully formed by using electroless plating and electroplating, which are more cost effective than vacuum evaporation. In this paper, we investigated low-cost Ni/Cu contact formation by electroless and electroplating for crystalline silicon solar cells.