• Journal of Preventive Medicine and Public Health
• /
• 제19권2호
• /
• pp.307-313
• /
• 1986

This study was carried out in order to estimate the residual amount of mercury in soy-bean sprouts in each steps of cooking. Samples were taken at markets and also cultured at home without applying the mercury containing pesticides as control. Mercury was determined by dithizone method. It was disclosed that soy-bean sprouts purchased at markets contained $1.32{\pm}0.274ppm$, 13 times as high as the maximal allowable concentration of mercury in food recommeded by Ministry of Health and Social Affairs. Mercury contents, however, dropped off steadily by steps of cooking: rinsed with distilled water and boiled in distilled water showing concentrations of $0.11{\pm}0.025ppm$ in boiled sprouts and $0.03{\pm}0.022ppm$ in sprout-soup. These values were not statistically different from those in control samples, and not exceeded the maximal allowabled levels of mercury in food. It can be concluded that the use of mercury containing pesticides in the cultivation of soy-bean sprouts is not so serious problem as it has been suspected in respect of food contamination, but careful attention must be paid to indiscriminate use of mercury containing pesticides as they may contaminate air, water and soil and secondarily bring harm to human health through food chains.

• 설비공학논문집
• /
• 제18권5호
• /
• pp.384-392
• /
• 2006

Reported are the heat transfer characteristics of a two-phase loop thermosyphon (TLT) with nanofluids consisted of nano-size silver particles and distilled water as the working fluid. The nanofluids used in the present study are dispersed solutions with various amount of silver nanoparticle in distilled water. It is seen from the present study that the heat transfer performance of the test TLT with nanofluids increased as much as about 2 times higher than that of a TLT with pure water as the working fluid based on same heat flux. The study also showed that there was no deterioration of the TLT performance with time, up to a period of 8 days of continuous operation which implies that there was no coagulation of nanoparticles within the working nanofluid during the operation of the test TLT.

• 한국산학기술학회논문지
• /
• 제16권3호
• /
• pp.1594-1599
• /
• 2015

세계 자동차 산업은 지난 100여년간의 내연기관의 시대에서 환경, 에너지 그리고 IT기술들이 접목된 친환경, 첨단자동차의 시대로 변모해가고 있다. 지금까지 자동차의 연구는 새로운 기술에 대한 연구 및 개발에 주력해 왔다. 자동차의 새로운 기술개발도 중요한 사항이지만, 최첨단 기술이 적용된 자동차 이전에 이미 사용되어지고 있는 자동차의 성능 및 환경개선 문제도 중요한 시점이 되었다. 새로운 기술개발 뿐 만아니라 기존의 기술에 대한 효과적인 적용 또한 중요한 사항이다. 부동액 기술 또한 자동차 기술의 중요한 부분이다. 본 연구는 부동액의 효과적인 적용을 위하여 자동차 엔진 냉각수에 함유된 부동액의 함유량과 냉각수의 종류(수돗물, 증류수, 지하수)에 따라 자동차 엔진 온도와 성능에 미치는 영향을 파악하고 원인을 규명하는 실험적 연구이다. 냉각수의 어는점 -10, -20, -30, -40, $-50^{\circ}C$에서 다이나모 성능시험과 수치해석을 실시하였다. 냉각수(증류수) 어는점 $-10^{\circ}C$에서 측정 기준점에서 최고 성능 71.112, 99.622hp를 나타냈다.

• 신재생에너지
• /
• 제8권2호
• /
• pp.24-32
• /
• 2012

Natural gas hydrates have a high potential as the 21st century new energy resource, because it have a large amount of deposits in many deep-water and permafrost regions of the world widely. Natural gas hydrate is formed by physical binding between water molecule and gas mainly composed of methane, which is captured in the cavities of water molecules under the specific temperature and pressure. $1m^3$ methane hydrate can be decomposed to the methane gas of $172m^3$ and water of $0.8m^3$ at standard condition. Therefore, there are a lot of practical applications such as separation processes, natural gas storage transportation and carbon dioxide sequestration. For the industrial utilization of methane hydrate, it is very important to rapidly manufacture hydrate. However, when methane hydrate is artificially formed, its reaction time may be too long and the gas consumption in water becomes relatively low, because the reaction rate between water and gas is low. So in this study, hydrate formation was experimented by adding natural zeolite and Synthetic zeolite 5A in distilled water, respectively. The results show that when the Synthetic zeolite 5A of 0.01 wt% was, the amount of gas consumed during the formation of methane hydrate was higher than that in the natural zeolite. Also, the natural zeolite and Synthetic zeolite 5A decreased the hydrate formation time to a greater extent than the distilled water at the same subcooling temperature.

• 수산해양기술연구
• /
• 제38권4호
• /
• pp.265-270
• /
• 2002

증류수 및 수도수 중에서 방열기로 사용되는 알루미늄합금재의 온도 변화, 탈기에 의한 개로전위, 부식전류밀도에 관하여 연구한 결과 다음과 같은 결론을 얻었다. 1. 청수 중에서 개로전위는 온도가 높아짐에 따라 비전위화 되고, 또한 탈기 후의 개로전위는 탈기 전의 개로전위보다 비전위화 된다. 2. 증류수 중에서의 부식전류밀도는 수도수 중에서의 부식전류밀도보다 더 억제된다. 3. 탈기 후의 부식전류밀도는 탈기 전의 부식전류밀도보다 크게 억제된다

• 한국환경기술학회지
• /
• 제19권6호
• /
• pp.493-502
• /
• 2018

수계의 조류발생 원인물질인 질소와 인을 제거할 목적으로 수처리용 EM 담체를 개발한 후, 물리적 특성에 대하여 검토한 결과는 다음과 같다. EM 담체를 제조하기 위한 점토 : 제올라이트 : 질석 : 활성탄의 배합비율은 10 : 2.5 : 0.1 : 2, 소성온도는 $700^{\circ}C$가 적합하였다. EM 담체의 공극률과 밀도는 39.98 %와 $1.13kg/m^3$, 질소와 인의 흡착효율은 69.3 %와 38.9 %, 증류수 담체의 공극률과 밀도는 37.80 %와 $1.11kg/m^3$, 질소와 인의 흡착효율은 62.5 %와 37.8 %로 나타났다. EM 담체가 증류수 담체에 비하여 질소의 흡착효율은 6.8 %, 인의 흡착효율은 1.1 %가 크게 나타났다. 담체의 질소와 인에 대한 흡착특성은 Freudlich 흡착등온식으로 표현이 가능하였다. 소성시간의 변화는 EM 담체를 성형할 때 질소의 인의 흡착효율에는 큰 영향을 미치지 못하였으나 담체의 강도에는 영향을 미칠 것으로 판단된다. 질소의 제거효율은 소성시간 4시간, 인의 제거효율은 소성시간 3시간에서 가장 우수하였다.

• 한국축산식품학회지
• /
• 제35권2호
• /
• pp.265-271
• /
• 2015

In a previous study, hydrolysates of porcine placenta were obtained and the extraction efficiency for proteins and amino acids was compared between sub- and super-critical water extraction systems; optimum efficiency was found to be achieved using subcritical water ($170^{\circ}C$, 10 bar). In this study, the effects of adding ethanol to the subcritical water system were investigated. The lowest-molecular-weight extraction product detected weighed 434 Da, and the efficiency of extraction for low-molecular-weight products was increased when either the concentration of ethanol was decreased, or the extraction time was lengthened from 10 min to 30 min. The highest concentration of free amino acids (approximately 8 mM) was observed following 30 min extraction using pure distilled water. The concentration of free amino acids was significantly lower when ethanol was added or a shorter extraction time was used (p<0.05). Color change of the solution following extraction was measured. There were no significant differences in color between lysates produced with different extraction times when using distilled water (p>0.05); however, using different extraction times produced significant differences in color when using 20% or 50% ethanol solution for subcritical extraction (p<0.05). The range of pH for the hydrolysate solutions was 6.4-7.5. In conclusion, the investigated extraction system was successful in the extraction of $\leq$ 500 Da hydrolysates from porcine placenta, but addition of ethanol did not yield higher production of low-molecular-weight hydrolysates than that achieved by DW alone.

• 동아시아식생활학회지
• /
• 제13권5호
• /
• pp.439-446
• /
• 2003

단식 증류기를 이용한 증류식 소주는 품격 높은 향미를 지니고 있으나 희석식 소주에 비해 상대적으로 고가인 것이 문제로 지적되어 왔다. 이에 증류식 소주의 경제성 확보 방법의 하나로 담금에 전분액화법을 도입하여 급수 변화에 따른 수율 및 향미 연구를 실시하였다. 액화담금공정에 의한 발효경과는 pH, 알코올, 총산 등의 일반분석 결과 정상적이었다. 수율은 급수율과 정비례관계를 보였으며 급수율 250%가 가장 높았다. one-way ANOVA를 이용한 p<0.05 수준에서의 Duncan's multiple range test 결과에서 급수율 변화에 따른 유의적인 차이를 보이지 않았고, 게다가 profile법에 의한 관능 평가 결과를 heptadiagram으로 나타내었을 때에도 그 면적과 형태의 유사성에서 보여지는 바와 같이 급수율 변화에 따른 관능차는 거의 없었다. 따라서, 본 연구에서는 급수율 250%로 액화 담금한 것이 품질 차이 없이 가장 높은 수율을 보여 경제적으로 우수하였고 발효경과에서도 문제가 없어 최적의 담금 방법임을 알 수 있었다.

• Journal of Acupuncture Research
• /
• 제32권3호
• /
• pp.117-126
• /
• 2015

Objectives : This study was an analysis of the anti-inflammatory, anti-oxidative and skin whitening properties of Gamioncheong-decoctione(GMOCD) extract. Methods : GMOCD(96 g) and 2 L of distilled water were heated at $100^{\circ}C$ for four hours and then concentrated, frozen, freeze-dried, dissolved in distilled water and filtered. The following analysis was completed: cell cytotoxic effect using MTT assay, oxidative products of NO by griess assay, concentration of prostaglandin $E_2(PGE_2)$ by commercially competitive enzyme immunoassay, and cytokines($IL-1{\beta}$, IL-6 and TNF-${\alpha}$) by Bio-Plex$^{(R)}$ Suspension Array System's Bio-Plex Pro$^{TM}$ mouse cytokine, chemokine, and growth factor assay. Anti-oxidative effect was measured using the DPPH method and skin whitening effect using tyrosinase inhibition assay. Results : GMOCD water-extract did not show any toxicity at all doses and cell viability was more than 90 % at all doses. GMOCD water-extract significantly inhibited NO production at doses of 100, 200, $400{\mu}g/ml$, significantly inhibited $PGE_2$ production at doses of 200 and $400{\mu}g/ml$ and reduced the LPS-induced IL-$1{\beta}$, IL-6 and TNF-${\alpha}$ production in a dose-dependent manner. $IL-1{\beta}$ production was significantly reduced at a dose of $400{\mu}g/ml$ and IL-6 production was significantly reduced at doses of 200 and $400{\mu}g/ml$. DPPH free radical scavenging capability had a skin whitening effect rate of more than 50%. Tyrosinase inhibition activity was apparent in a dose-dependent manner. Conclusions : This study suggests that GMOCD water-extract suppressed NO and $PGE_2$ production and inhibited cytokines($IL-1{\beta}$, IL-6 and TNF-${\alpha}$). GMOCD also improved DPPH free radical scavenging capability. GMOCD water-extract increased tyrosinase inhibitory activity in a dose-dependent manner but this was not a statistically significant result.

• Preventive Nutrition and Food Science
• /
• 제10권2호
• /
• pp.111-117
• /
• 2005

Radical scavenging activity of water and methanol extracts of mulberry juice and cake prepared from mulberry fruit (Morus spp.) was evaluated using three in vitro assay systems. Mulberry fruits were homogenized with $0.5\%$ trifluoroacetic acid (TFA) in distilled water, filtered with cheeze-cloth and centrifuged to yield mulberry juice and cake. Mulberry juice was evaporated and solubilized in $0.5\%$ TFA in distilled water or $0.5\%$ TFA in $80\%$ aqueous methanol, followed by filtration and evaporation to obtain water (WMJ) and methanol (MMJ) extracts of mulberry juice. Mulberrry cake also was extracted with the above same solvents, and thereby finally obtaining water (WMC) and methanol (MMC) extracts of mulberry cake. Among four extracts, the MMC showed the most potent radical scavenging activity against DPPH radical $(IC_{50}=167.45\;{\mu}g/mL)$, and superoxide $(IC_{50}=36.18\;{\mu}g/mL)$ and hydroxyl radicals $(IC_{50}=467.08\;{\mu}g/mL)$. The WMC also exhibited stronger radical scavenging activity than those of two other mulberry juice extract, WMJ and MMJ. Meanwhile, the MMJ exerted stronger three radical scavenging activity than the WMJ. Total phenolic content of the water and MeOH extracts from mulberry cake was higher than that of the water and MeOH extracts from mulberry juice. Thus, these results suggest that the extracts of mulberry cake with high dietary phenolics may be useful potential source of natural antioxidant as radical scavenger.