• Tribology and Lubricants
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• 제16권5호
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• pp.332-340
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• 2000

The reduction of sulfur content in the diesel fuel has caused the poor lubricity of diesel fuel in the distributor type injection pumps of diesel engines that use the diesel for lubrication of their moving parts. To investigate the reason for poor lubricity of low sulfur diesel fuels, the wear scar diameters by HFRR (High Frequency Reciprocating Rig) were measured on the diesel fuels from Korean markets and the results were compared with their physical and chemical properties. Also, the lubricity change and the improvement effects on lubricity additives for the ultra low sulfur diesel fuel, were made experimentally, that will be regulated to a maximum of 0.005 wt% from about 2005 were evaluated. As a result, a good correlation was found between the wear scar diameter and the polyaromatic compound which includes heterocyclic compound in the diesel fuel. It was also found that the content of polyaromatic compound including heterocyclic compound was affected by the amount of desulfurization treatment fraction. And the lubricity additives with ester base were more effective than that with acid base on the ultra low sulfur diesel fuel. Therefore, it is suggested that the factors affecting the lubricity stated above should be taken into account to improve the lubricity property of the diesel fuel in the refining process.

• Food Science and Biotechnology
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• 제16권1호
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• pp.1-7
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• 2007

Garlic (Allium sativum L.) contains a specific sulfur compound, the S-allyl derivative of L-cysteine sulfoxide, and has long been known for its antimicrobial activity against various microorganisms, including bacteria, fungi, and protozoa. The principal antimicrobial compound of garlic is S-allyl-L-propenethiosulfinate (allicin) which is generated by an enzyme, alliinase (L-cysteine sulfoxide lyase), from S-allyl-L-cysteine sulfoxide (alliin). This compound exists exclusively in Allium as a major non-protein sulfur-containing amino acid. S-Allyl-L-propenethiosulfinate belongs to the chemical group of thiosulfinates and is a highly potent antimicrobial. The potency of garlic extract is reduced during storage since thiosulfinates are unstable and are degraded to other compounds some of which do not have antimicrobial activity. Diallyl polysulfides and ajoene are sulfur compounds derived from allicin that do possess antimicrobial activity. It was recently found that garlic becomes antimicrobial on heating at cooking temperatures, and that the compound responsible for this is allyl alcohol, which is generated from alliin by thermal degradation.

• Food Science and Biotechnology
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• 제18권3호
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• pp.771-775
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• 2009

Antimicrobial activity of garlic (pH 6.0) heated at $120^{\circ}C$ reached its maximum at 45 min of heating and maintained the level for the rest of heating time (300 min) when tested against Candida utilis ATCC42416. The principal antimicrobial compound was allyl alcohol (AA), a highly volatile compound without sulfur in its molecule. The concentration of AA in heated garlic gradually increased to over 2,000 ppm for the first 90 min and stayed at the level without appreciable changes in spite of further heating. Other antimicrobial compounds secondary to AA were lowly volatile sulfur compounds including diallyl polysulfides (diallyl trisulfide, diallyl tetrasulfide, and diallyl pentasulfide) and heterocyclic sulfur compounds (4-methyl-1,2,3-trithiolane, 5-methyl-1,2,3,4-tetrathiane, and 6-methyl-1,2,3,4,5-pentathiepane). When the pH of the garlic extract was lowered before heating, considerably more secondary antimicrobial sulfur compounds were formed and the antimicrobial activity was stronger than the pH unadjusted garlic. Lowly volatile sulfur compounds contributed a significant part of antimicrobial activity of heated garlic only during the early period (45-120 min) of heating regardless of pH treatment.

• Elastomers and Composites
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• 제56권4호
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• pp.223-233
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• 2021

In this study, epoxidized liquid isoprene rubber (E-LqIR) was used as a processing aid in a silica-filled natural rubber compound to improve the fuel efficiency, abrasion resistance, and oil migration problems of truck and bus radial tire tread. The wear resistance, fuel efficiency, and extraction resistance of the compound were evaluated according to the molecular weight of E-LqIR. Results of the evaluation showed that the E-LqIR compound had a lower chemical crosslink density than that of a treated distillate aromatic extract (TDAE) oil compound because of the sulfur consumption of E-LqIR. However, the filler-rubber interaction improved because of the reaction of E-LqIR with silica and crosslink with the base rubber by sulfur. As the molecular weight of E-LqIR increased, crosslink with sulfur was facilitated, and the filler-rubber interaction improved, resulting in improved abrasion resistance. The fuel efficiency performance of the E-LqIR compound was poorer than that of the TDAE oil compound because of the low chemical crosslink density and hysteresis loss at the free chain end of E-LqIR. However, the fuel efficiency performance improved as the molecular weight of E-LqIR increased.

• 한국초지조사료학회지
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• 제8권3호
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• pp.152-157
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• 1988

The effect of gypsum application was tested on dry matter yield, sulfur uptaken, composition of Ritrogen compound and sulhr compound and sulfur balance in mixed pasture. Total dry matter yields and sulfur uptake by grasses increased with the increasing of gypsum application rates. The ratios between total nitrogen and total sulfur in masses decreased with the increase of sulfur uptake at 2nd and 3rd cutting times. Cysteine content was little affected by gypsum while methionine content slightly increased an 4.0, 6.0 kg3 per 10a levels at 2nd and 3rd cutting times. The uptake of nitrate nitrogen decreased with gypsum application and dry matter digestibility increased about 1.1 to 3.3%. The soil pHs after experiment become high in surface and subsoil till 6.0 kg.S per 10a, but low at 10.0 kg.S per 10a. The content of sulfur in surface soil was 19.9 ppm after experiment, but very high in subsoi1,ranging from 94 to 143 ppm.S. Sulfur leached from the surface soil by 0.69, 2.39, and 6.24 kg.S per 10a in the plots of 4.0, 6.0, and 10.0 kg.S per 10a, respectively.

• 폴리머
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• 제39권2호
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• pp.240-246
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• 2015

양기능성 실란 커플링제인 bis(triethoxysilylpropyl)tetrasulfide(TESPT)가 실리카/천연고무 복합소재 내에서 실리카의 hydroxy기와 고무 계면간에 화학적 결합반응을 하여 실리카-실란-고무간의 3차원 사슬구조를 형성한 것을 열분해 가스 크로마토그래피 질량분석기(Py-GC/MS)와 주사전자현미경(SEM)을 통해 관찰하였다. TESPT의 첨가로 배합물 내의 황 함유율이 증가하여 스코치 시간($t_{10}$)은 감소하고, TESPT 내 sulfur donor 역할을 하는 황이 활성화제 및 촉진제와의 복합반응으로 가교반응이 지속적으로 이루어짐에 따라서 가교속도지수(CRI)의 값이 감소하였다. 또한 TESPT가 첨가된 컴파운드는 첨가되지 않은 컴파운드에 비해 가공성 및 기계적 물성이 향상되었다. 결과적으로, 실리카로 충전된 천연고무 복합소재에 실란 커플링제(TESPT)가 첨가되어 화학반응으로 실리카-실란-고무간의 3차원 사슬구조가 형성됨을 관찰하였고 이에 따라 가교밀도가 증가하여 복합소재의 물성 증가에 기여함을 보여주었다.

• 한국군사과학기술학회지
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• 제18권5호
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• pp.548-557
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• 2015

This paper is results on Chemisorption of organic compound for the sea water fire fighting line of naval vessels. The quantitative analysis of Chemisorption has been investigated in seawater after immersion in 0.1 % of NaDDTC solutions for 43 hours. The morphology and topography were investigated by FE-SEM and AFM. The chemical elements were analyzed by SEM-EDS, XPS and the depth of chemical elements was measured by depth profiles. The effect of NaDDTC comes from Chemisorption between Copper and Sulfur of NaDDTC. As a result, test results showed that sulfur is helpful to protect a corrosion of seawater line.

• Elastomers and Composites
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• 제33권4호
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• pp.274-280
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• 1998

가황반응에 대한 반응차수, 반응속도상수 및 활성화에너지, 가교결합에 의한 가교밀도 및 탄성상수를 동일한 가황시스템하에서 실리카와 카본블랙을 함유한 SBR/BR 블렌드에 대하여 조사하였다. 반응차수는 충전제 종류에 관계없이 1차 반응이었으며, 카본블랙이 첨가된 배합고무는 실리카가 첨가된 배합고무보다 반응속도가 빠르게 나타났다. 그러나 활성화에너지는 충전제 종류 및 고무 블렌드 조성에 관계없이 일정하게 나타났다. 가교밀도 및 탄성상수는 고무와 카본블랙간의 강한 상호작용으로 인해 카본블랙이 첨가된 조성물에서 높게 나타났다. 한편, 고무 블렌드중 부타디엔 고무 함량이 증가할수록 가교밀도 및 탄성상수는 감소하였다. 가황고무중 결합 황 함량 비교결과, 실리카가 첨가된 조성물중 일정한 결합 황 함량은 반응시작 후 20분 후에 나타났으나, 카본블랙이 첨가된 조성물은 10분 후에 나타났다. 또한 실리카가 첨가된 조성물은 카본블랙이 첨가된 조성물에 비해 반응 유도시간($t_2$) 및 최적 가황시간($t_{90}$)이 길게 나타났다.

• 한국식품조리과학회지
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• 제19권1호
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• pp.17-23
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• 2003

This study was performed to find the changes in volatile sulfur compounds of garlic under various storage conditions. The volatile sulfur compounds of garlic were identified with GC and GC/MS. Analysis on the detected volatile sulfur compound of garlic which is known to have medical effect was performed while storing for two days at room temperature and for 1, 3 and 7 days at 4$^{\circ}C$ and -18$^{\circ}C$, respectively. The results of the study were summarized as follows : Total amount of 7 volatile sulfur compounds was the highest in the sample stored at room temperature for one hour. During the storage of 1, 3 and 7 days at -18$^{\circ}C$, chopped garlic contained more of volatile sulfur compounds than under any other storage conditions and the amounts of 7 volatile sulfur compounds increased gradually during the storage of chopped garlic.

• 한국산학기술학회논문지
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• 제11권8호
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• pp.2935-2941
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• 2010

본 논문은 SLS의 함유정도를 다르게 한 A(0%), B(1.1%), C(2.2%)의 세가지 실험세치제를 제작하여 구취변화를 실험하였다. 대상은 전신질환이 없는 20대 성인 150명이었으며 50명씩 세 그룹(A, B, C )으로 나누어 진행되었다. SLS함량에 따른 세치제의 4주간사용 후 3집단의 구취변화를 황화물가스와 암모니아 양의 변화로 측정한 결과 3집단 모두 집단내의 변화는 있는 것으로 나타났지만 SLS함량에 따른 상관관계를 본 결과에서는 구강황(r=0.412)과 호기황(r=0.285)에서만 상관관계가 있는 것으로 나타났다. 이는 잇솔질의 개선으로 인한 변화라고 볼 수 있으며 SLS의 함량이 높을수록 타액분비율을 저하시켜, 구강건조를 유발하므로 구강 황화합물과 호기 황화합물의 수치가 높게 나온 것으로 생각된다.