• 한국화재소방학회:학술대회논문집
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• 한국화재소방학회 2002년도 춘계학술대회 논문집
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• pp.163-167
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• 2002

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2006년 창립20주년기념 정기학술대회 및 국제워크샵
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• pp.145-149
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• 2006

The effect of alkaline environmental condition on durability of GFRP composites according to additives has been investigated. Additives used were polyvinyl alcohol (PVA), kaolin and alumina powder. Weight gains increased with immersion time in all GFRP composites at $80^{\circ}C$. But weight gain of specimen added PVA did not differ through the whole immersion time in both tap water and alkaline solution at 20 and $80^{\circ}C$. Tensile strength decreased with immersion time in all environment conditions. Tensile strength of GFRP composites regardless of additives decreased rapidly up to 5 days of immersion and then decreased slowly up to 30 days in alkaline solution environment at $80^{\circ}C$. The weight gains were not much difference in both tap water and alkaline solution at $20^{\circ}C$. But the ones of GFRP composites added PVA was smaller than the composites without additive in all aqueous at $20^{\circ}C$. Test strength of GFRP composites added polyvinyl alcohol has improved through the whole immersion time in both tap water and alkaline solution environment at $20^{\circ}C$.

• Computers and Concrete
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• 제19권4호
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• pp.357-363
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• 2017

This paper conveys the effects of fly ash and silica fume incorporated in concrete at various replacement ratios on the durability properties of concretes. It is quite well known that concrete durability is as much important as strength and permeability is the key to durability. Permeability is closely associated with the voids system of concrete. Concrete, with less and disconnected voids, is assumed to be impermeable. The void system in concrete is straightly related to the mix proportions, placing, compaction, and curing procedures of concrete. Reinforced concrete structures, particularly those of subjected to water, are at the risk of various harmful agents such as chlorides and sulfate since the ingress of such agents through concrete becomes easy and accelerates as the permeability of concrete increases. Eventually, both strength and durability of concrete reduce as the time moves on, in turn; the service life of the concrete structures shortens. Mineral additives have been proven to be very effective in reducing permeability. The tests performed to accomplish the aim of the study are the rapid chloride permeability test, pressurized water depth test, capillarity test and compressive strength test. The results derived from these tests indicated that the durability properties of concretes incorporated fly ash and silica fume have improved substantially compared to that of without mineral additives regardless of the binder content used. Overall, the improvement becomes more evident as the replacement ratio of fly ash and silica fume have increased. With regard to permeability, silica fume is found to be superior to fly ash. Moreover, at least a 30% fly ash replacement and/or a replacement ratio of 5% to 10% silica fume have been found to be highly beneficial as far as sustainability is concerned, particularly for concretes subjected to chloride bearing environments.

• Journal of Pharmaceutical Investigation
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• 제25권3호
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• pp.177-184
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• 1995

In order to formulate an aqueous topical preparation of epidermal growth factor(EGF) for the treatment of open wound and bum, the stability of EGF in aqueous vehicles containing various stabilizers was evaluated and the pharmacological activity of gel preparations formulated with poloxamer 407 was determined with wound model. Various additives, which are known as potent stabilizers for proteins and polypeptides so far, were used to increase the stability of EGF in aqueous vehicles. The contents of EGF in the vehicles containing stabilizers were determined with an HPLC method after the storage at $37^{\circ}C$. EGF was more stable in ultrapure water than RO water or saline. All the additives studied resulted in deleterious effects on EGF stability. Therefore, it was speculated that any additives or impurities in the vehicle made EGF unstable. However, nitrogen purge of solution increased the stability of EGF in aqueous vehicles. The aqueous topical preparations of EGF were formulated with poloxamer 407 as a gel base in saline. Gelatin or amastatin was employed as a protease inhibitor. The pharmacological effect of EGF gel was studied with open wound model in mice. EGF preparations, made of oleaginous base or poloxamer gel base, showed significant healing effect compared to the control group(p<0.05). The addition of protease inhibitor in poloxamer 407 gel resulted in significant healing effect compared to the gel without it(p<0.05). Body weights of mice treated with EGF preparation were increased at the first day after the formation of open wound, while those of the control group were decreased. The EGF gel made of poloxamer 407 containing a pretense inhibitor would be a promising aqueous topical preparation for EGF.

• 한국화재소방학회:학술대회논문집
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• 한국화재소방학회 1997년도 International Symposium on Fire Science and Technology
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• pp.130-137
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• 1997

Intumescent inorganic and organic coatings which dintr one from the other by the type of gas formers and the mechanisms of foam formation have been obtained and investigated. Inorganic intumescent coatings are the compositions based on water glass and mineral additives with different dispersity. Mineral additives contain adsorbed and absorbed water and carbonates which are destructed with the carbon dioxide and water evolution during the flame action on coating. The decreasing of mineral additives particle sizes under the mechanical milling with the fraction precipitation promotes the foam coke formation with less defects. Here the main structure of comparing compositions does not change. In organic coatings based on epoxy-polymers the polyammonium phosphate additive is used. It is the cabonization catalyst and the foam agent. The polyammonium phosphate of various dispersity employed is uniformly distributed on the polymeric matrix. The decreasing of the particle sizes leads to the increasing of the fire resistant properties of the intumescent coa-ting. The fire resistant analysis of the coating during more than an hour: the coating back side the temperature on plastic or wooden materials does not exceed 423K, and on metal-573K.

• 한국축산식품학회지
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• 제41권6호
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• pp.1060-1077
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• 2021

Food additives are required to maintain the freshness and quality of foods, particularly meats. However, chemical additives may not be preferred by consumers, and natural materials with antimicrobial and antioxidant effects may be used as replacements for common chemical additives. Accordingly, in this study, we compared the antimicrobial and antioxidant activities of natural compounds extracted with ethanol and hot water, and emulsion sausage prepared with natural ethanol extracts was analyzed for pH, color, thiobarbituric acid reactive substances (TBARS), and Clostridium perfringens growth during storage. The antimicrobial activities of 49 natural extract candidates against Listeria monocytogenes, C. perfringens, Salmonella spp., and Escherichia coli were analyzed, and six natural materials with excellent antibacterial activities, i.e., Elaeagnus umbellata Thunb. f. nakaiana (Araki) H. Ohba, Punica granatum L., Ecklonia cava, Nelumbo nucifera Gaertner, and Schisandra chinensis (Turcz.) Baill., and Rubus coreanus Miq. were evaluated to determine their total polyphenol contents and DPPH radical scavenging activities. The total polyphenol contents of ethanol extracts were higher than those of hot water extracts, whereas DPPH radical scavenging activity was found to be higher in hot water extracts. The TBARS values of emulsion sausages were significantly increased as storage time increased, and the TBARS values of emulsion sausages prepared with natural extracts were lower than those of control sausages. Natural extract-treated emulsion sausages showed a 99% reduction in bacterial contents compared with untreated sausages on day 2, with greater than 99.9% reduction after day 3. Thus, these results demonstrated that natural extracts could have applications as natural preservatives in meat products.

• 공업화학
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• 제29권1호
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• pp.112-116
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• 2018

주조공정 중 주형제조 시 점결제로 사용되는 silicate계 바인더의 주요원료 중 하나인 물유리와 첨가제(Si, 알칼리 금속)의 혼합특성을 살펴보았다. 물유리와 첨가제 그리고 비율에 따라 제조된 혼합물은 FT-IR분석을 통해 분자결합구조를 살펴보았으며, 점도측정으로 분자구조와의 상관관계를 비교하였다. 물유리에 Si 소스의 제공은 물질 내 Si 망상결합을 촉진시켜 점도는 증가하였고, 알칼리 금속을 첨가하였을 경우에 물유리의 Si 망상결합을 억제하여 점도가 낮아졌다. 물유리와 리튬 실리케이트(lithium silicate, LS)의 혼합물의 점도는 LS의 함량이 20 wt% 이하에서는 LS의 함량이 증가할수록 증가하였지만, 20 wt%를 초과할 경우 점차 낮아졌다. 물유리에 KOH를 첨가함으로써 점도를 낮출 수 있었으며, 콜로이달 실리카(colloidal silica, CS) 또는 potassium methyl siliconate (PMS)와의 혼합을 효과적으로 이용하는 데 이용할 수 있다.

• 한국조리학회지
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• 제5권2호
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• pp.471-483
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• 1999

국수조리시에 조직감을 높이기 위해 소금, 설탕, 기름 그리고 구연산을 각각 1%의 농도로 끊는물에 넣고 국수의 조리 특성과 조직감을 측정한 결과 1%의 소금을 첨가하여 국수를 삶은 경우 83g의 무게를 보였으며, 삶은 후의 부피 또한 78m1로 낮은 흡수율을 보였으나 삶는 과정에서 용출되는 고형물의 탁도는 높았다. 그리고 조직감의 측정결과 역시, 1% NaCl의 첨가가 조직감이 우수하였다. 다른 첨가제들에서는 조직감의 유의적 차이가 별로 없었다. NaCl의 첨가농도를 달리하여 조리특성을 측정해 본결과 농도가 증가할수록 조리후의 무게와 부피의 증가가 감소하는 경향을 보였다. NaCl 첨가농도가 6%일 때 조직감을 비교하였을 때 첨가하지 않은 경우에 비해서 조직감의 유의적 차이를 보였다. 일반적으로 우리가 사용하는 소금의 첨가가 국수의 조직감에 영향을 미친다는 것을 알 수 있었다.

• 콘크리트학회지
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• 제10권6호
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• pp.223-231
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• 1998

종래의 시멘트 모르터 그라우트 방식에 의한 제자리 콘크리트 말뚝은 시공후 자기수축 및 건조수축 등에 의하여 말뚝의 내력이 저하하고, 지하수에 의하여 재료분리가 발생하며, 많은 단위시멘트량에 의한 비경제성 등이 문제시되고 있다. 그러므로 본 연구는 팽창제 및 플라이애쉬 등 각종 혼화재료를 이용한 제자리 콘크리트 말뚝용 고성능 시멘트 모르터의 역학적 성질이 분석되었다. 실험결과 팽창재 혼입율이 증가함에 따라 유동성은 감소하고, 공기량은 증가하며, 응결시간은 지연되고 압축강도는 7일에서는 감소하나 28일 및 91일 재령인 경우는 팽창제혼입율 5%에서 약간 상승하는 것으로 나타났다. 플라이애쉬치환율이 증가함에 따라 유동성은 양호해지고, 공기량은 증가하며, 응결시간은 지연되고 압축강도는 약간 감소하였다. 또한 길이변화특성은 팽창재혼입율이 증가할수록 크게 팽창하고, 플라이애쉬치환율이 증가할수록 수축은 작은 것으로 나타났다.

• 한국환경과학회지
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• 제19권11호
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• pp.1385-1390
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• 2010

Repeated additions of untreated slurry to soil affected ecology and caused high levels of heavy metal in soil and ground water. The objective of this study was to evaluate heavy metal from hanwoo slurry with ferrous sulfate ($FeSO_4{\cdot}7H_2O$), aluminum sulfate [$Al_2(SO_4)_3{\cdot}14H_2O$, alum] and aluminum chloride ($AlCl_3{\cdot}6H_2O$) as a way to improve environmental management in hanwoo industry. The treatment rates, which were incorporated totally within the hanwoo slurry, were 1.0 g and 1.5 g of ferrous sulfate, alum and aluminum chloride/25 g of hanwoo slurry. The various rates of chemical additives significantly increased dry matter (9.98~13.94%) and decreased pH (3.48~6.52) compared with the controls. The use of chemical additives decreased Fe (11~29%), Al (7~12%), Zn (13~36%), and Cu (4~32%) contents, except for Fe in hanwoo slurry with ferrous sulfate and Al in hanwoo slurry with alum and aluminum chloride. In addition, the reduction in heavy metal should be associated with reduction in pH. In conclusion, the results of this study suggest that alum and aluminum chloride additives at rate of 1.5 g were cost-effective management practice that significantly reduces heavy metal from hanwoo slurry, while it may be improved environmental management.