• Journal of Environmental Health Sciences
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• v.24 no.3
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• pp.92-98
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• 1998

작업장에서 근로자들이 엔진오일 등 각종 오일에 피부가 폭로되었을 때 이것을 쉽게 세척하기 위하여 일반적으로 솔벤트를 사용한다. 그러나 솔벤트를 사용하면 피부를 건조하게 만들 뿐만 아니라 오일에 함유되어 있는 각종 성분들을 피부내에 흡수되는 것을 촉진시킬 수 있어서 이에대한 대처방법이 요구된다. 특히 폐가솔닐엔진오일데는 방향족탄화수소(PAHs)와 같은 물질이 함유되어 있어 체내에 흡수되면 발암물질로 대사되어 표적장기(피부와 폐조직)에서 DNA adducts를 높은 수준으로 형성한다고 알려져 있다. 본 연구에서는 식물기름에서 구할 수 있는 d-라이모닌(Limonene)를 세척제로 사용하여 폐가솔린엔진오일의 폭로로 인하여 형성되는 DNA adducts를 $^{32}P-postlabeling방법으로 분석함으로써 d-라이모닌의 세척효과를 평가하고자 하였다. HDC(ICR) Br 자성마우스의 견갑골 부위에 있는 털을 제거하고 그 부위에 폐가솔린엔진오일을 폭로시키고 1시간과 8시간이 지난 다음에 d-라이모닌으로 각각 세척을 하였다. 마지막 폭로를 마치고 24시간이 지난 다음에 실험동물을 희생시켜 표적장기(폭로된 피부와 폐)에서 시료를 채취하였다. 먼저 시료에서 DNA를 분리하여 가수분해한 다음에 $^{32}P-postlabeling하여 DNA adducts를 분리하였다. 폐가솔린엔진오일만 폭로시킨 그룹의 피부와 폐조직에 형성된 DNA adducts가 각각 30.3$\pm$3.7과 15.7$\pm$2.4로서 대조군(2.5$\pm$1.0과 1.4$\pm$0.4)에 비하여 통계적으로 유의하게 높았고 (p<0.01), 또한 폐조직에서 보다 피부조직에서 통계적으로 유의하게 높았다(p<0.01). 폐가솔린엔진오일을 폭로시킨 후에 d-라이모닌으로 세척한 그룹에서는 피부와 폐조직에 형성된 DNA adducts가 통계적으로 유의하게 감소하였는데(p<0.01), 8시간 보다는 1시간이 지난 다음에 세척한 그룹에서 DNA adducts의 감소현상이 더 크게 나타났다. 결론적으로 피부에 폭로된 폐가솔린 엔진오일을 d-라이모닌으로 세척하면 폐가솔닐엔진오일내에 함유된 발암물질이 체내흡수되는 것이 억제되고, 피부와 폐조직 모두에서 DNA adducts의 형성을 감소시킬 수 있으며, 폐오일이 폭로된 후 빨리 세척하는 것이 더 효과적임을 증명하였다.

• Journal of the Korea Convergence Society
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• v.9 no.7
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• pp.149-154
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• 2018

This article intended to examine the anti-plaque activity of 4 essential oils of Lavender, Tea tree, Eucalyptus, Lemongrass against Streptococcus mutans. In the results of measuring the anti-plaque effect against Streptococcus mutans, Minimum anti-adhesive concentration of Lavender oil was 1.0% and that of Tea tree, Eucalyptus, lemongrass essential oils was 0.5 %. Also, it was confirmed that the essential oils have the effect of inhibiting acid generation by Streptococcus mutans. It was confirmed that pH of the concentration was lowered by the acid generation under the MAC by measuring pH of the solution after incubating Streptococcus mutans and the essential oils in the thermostatic bath varying their concentration. From these results, the essential oils, particularly, Tea tree, Eucalyptus, Lemongrass essential oils are the natural material inhibiting the plaque generation and the potential that they can be used to develop the oral care products was confirmed.

• Journal of the Korean Society for Marine Environment & Energy
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• v.15 no.1
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• pp.19-21
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• 2012

The engine oil life of internal combustion engine is shorted by the thermal effect and that causes air pollution. In order to measure the status of engine oil accurately, the exchange of new oil extends the life of combustion engine and reduces environmental pollution. Capacitance probes, such as engine oil and fluids can be used to measure the dielectric constant. In this paper, the degradation of engine oil varies depending on the degree of dielectric properties was analyzed. Depending on the state of the oil, the variant capacitance of the probe was measured by LCR Meter, respectively, and then the permittivity of oil was calculated. In addition, according to the size of the probe by measuring the change in capacitance measurement, accuracy of dielectric constant are presented. According to oil contaminated with the more increase in dielectric constant, we can decide that contaminated oil is available.

• Journal of Korean Society of Transportation
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• v.26 no.6
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• pp.29-38
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• 2008

In Seoul, the volume of office market has been expanding rapidly and the currency will be maintained. Many researches have looked at determinants of the office rent, we still cannot have adequate and accurate information of the impacts of traffic congestions around office buildings on the office rents. To gauge the effect of traffic conditions surrounding an office building on the office rent, a hedonic price model was estimated. The regression analysis estimates the values or implicit prices of the individual rent determinants; these parameters in turn allow for a detailed examination of the variables that impact office rents. The result shows that traffic conditions of office buildings play an important role in determining the office rental rate. Since a number of adjacent streets provided excellent opportunities to connect with the neighborhood, it pulls up the rental rate. Similarly, traffic congestions depreciates the value of an office buildings restricting the accessibility to the office building. We also provide evidence of the existence of spatial submarkets and find that market takes different spatial forms depending on the local context.

• Clean Technology
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• v.25 no.4
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• pp.275-282
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• 2019

In this study, the extraction of Conger myriaster oil by using supercritical carbon dioxide (SC-CO₂) and organic solvent was investigated. The extraction conditions conducted for SC-CO₂ varied for pressure (25, 30 MPa) and temperature (45, 55 ℃), while the SC-CO₂ flow rate was kept constant during the experiment (27 g min^-1) and hexane was used as a conventional organic solvent. The extraction yield indicated that the best extraction condition would be SC-CO₂ at 55 ℃ and 30 MPa, resulting in the highest yield of 37.73 ± 0.14%. The oils were characterized for their fatty acid (FAs) composition using gas chromatography, while it was revealed that the major FAs were mystric acid, palmitoleic acid, oleic acid, electroosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). The oxidation stability of the extracted C. myriaster oil was evaluated by measuring the acid value, peroxide value, and free fatty acid. The best oxidative stability was obtained from SC-CO₂ extracted oil at 30 MPa and 55 ℃. There was a significant difference in the color properties of the SC-CO₂ and hexane extracted oils, with the SC-CO₂ extracted oil showing better chromaticity than the oil extracted using hexane. Extracting oils from C. myriaster with SC-CO₂ could bring better economic benefits than using organic solvents. When supercritical carbon dioxide was used, there was no post-treatment process; thus, it was confirmed that this is a more environmentally friendly oil extraction method.

• Journal of Applied Biological Chemistry
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• v.56 no.3
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• pp.141-146
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• 2013

Constituents of the essential oil (EO)s and hydrosol of rosemary (Rosmarinus officinalis L.) and lavender (Lavandula angustifolia Mill.) were analyzed by gas chromatography-mass spectrometry (GC-MS). The identified major constituents were ${\alpha}$-pinene (40.96%), camphor (34.44%), verbenone (45.31%), and camphor (67.04%) in rosemary EO, lavender EO, rosemary hydrosol, and lavender hydrosol, respectively. The antioxidant activity of EO and hydrosol extracted from rosemary and lavender were evaluated. Both EO showed di(phenyl)-(2,4,6-trinitrophenyl) iminoazanium (DPPH) and 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) free radical scavenging activities as well as $Fe^{2+}$ ion chelating activity but no alkyl radical scavenging activity. Rosemary EO showed higher DPPH radical scavenging activity than lavender, whereas lavender EO showed higher $Fe^{2+}$ ion chelating activity. Both rosemary and lavender hydrosols showed alkyl radical scavenging activity, but only lavender hydrosol showed an activity on $Fe^{2+}$ chelating assay. Both rosemary and lavender hydrosols also protected the dermal fibroblast and the HaCaT keratinocytes against $H_2O_2$-induced cytotoxicity.

• 한국방재학회:학술대회논문집
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• 2011.02a
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• pp.194-194
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• 2011

현대 사회에서 차량을 비롯한 선박, 항공기와 같은 각종 수송수단들은 그 용도와 형태도 다양하고 널리 보급되어있을 뿐만 아니라 각 분야에서 없어서는 안 될 필수품이 되어 있다. 그러나 수송수단의 수와 활용빈도수가 증가함에 따라 그로 인한 차량화재, 선박화재 그리고 항공기화재 등과 같은 특수화재의 발생에 따른 재산 및 인명피해의 문제점들도 함께 늘어나고 있는 실정이다. 2009년 기준, 1년 동안의 전체 화재발생건수 47,071건 가운데 차량화재의 발생건수가 5,958건으로서 전체의 12.6% 정도를 차지하였다. 그뿐만 아니라 차량 내장재의 주 재질은 가연성을 지닌 열가소성 합성수지들로서 화재가 발생하였을 경우, 다량의 가연성 가스 및 독성가스를 방출하기 때문에 인명 및 재산 피해를 증가시키는 문제점을 갖고 있다. 하지만 아직까지도 이와 같은 수송수단에 대한 화재를 예방하거나 피해를 최소화할 수 있는 화재진압대책 등에 관한 연구는 미흡한 실정이다. 따라서 본 연구에서는 이러한 문제점을 해결하고 과학적이며 체계적인 대응방안을 수립하기 위한 기초 자료를 확보하고 이를 통한 수송수단의 화재안전성을 분석하고자 각종 수송수단에서 사용되는 오일을 대상으로 연소특성 분석 및 화재하중에 관한 연구를 수행하였다. 분석 대상 오일은 연료용과 부속용 오일로 크게 분류되며, 연료용 오일로는 차량용 경유와 휘발유 그리고 군용차량용 경유, 항공기용 백등유와 제트유, 선박용 고유황경유 등을 선정하였다. 부속용 오일로는 브레이크오일, 파워오일, 엔진오일, 자동변속기오일, 수동변속기오일을 대상으로 각각 일반용과 고급형 2가지씩 시료를 선정하여 분석을 수행하였다. 분석방법은 대상오일들의 기초물성을 고찰하기 위해서 비중계를 이용하여 각 시료들의 비중을 측정하였으며, 문헌으로부터 끓는점, 어는점 및 점도 등을 조사하였다. 또한, 대상오일들의 착화특성을 살펴보고자 콘칼로리미터와 인화점 측정기 및 발화점 측정기 등을 이용하여 발열량, 착화시간, 발연량, 발화점, 인화점 등을 측정하였다. 대상오일들의 물성 및 착화특성에 대한 측정결과를 살펴보면, 비중은 $725.8{\sim}1072.0kg/m^3$ 정도의 값을 나타냈고, 인화점은 영하의 인화점을 갖는 휘발유의 경우, 장비의 특성상 분석이 곤란하여 측정하지 못하였으며, 다른 시료들은 $45.3{\sim}266.6^{\circ}C$정도의 값을 나타냈다. 발화점은 $325.7{\sim}600.6^{\circ}C$정도의 값을 갖는 것으로 나타났다. 따라서 이와 같은 결과들을 활용하면 차량, 선박, 항공기 등에 대한 화재발생과 관련된 화재안전성을 분석하고 이를 통한 수송시스템의 화재에 대한 예방 및 대응 방안의 효율성을 높일 수 있을 것으로 생각된다.

• Elastomers and Composites
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• v.47 no.1
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• pp.36-42
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• 2012

More than 3 wt% of polycyclic aromatics (PCAs) in process oil is known to cause skin cancer. The criterion of distinguishing between low PCA oil and high PCA oil is based on 3 wt% of PCA. High PCA oil is called as a carcinogen like distillate aromatic extract (DAE). Low PCA oil is considered as safety oils like treated distillate aromatic extract (TDAE), mild extract solvate (MES), and paraffinic oil. Four types of process oils such as DAE, TDAE, MES, and paraffinic oil purified by solvent extraction and separation skills from SBR vulcanizates were measured by FT-IR techniques. The effects of rubber chemicals such as N-1,3-dimethylbutyl-N'-phenyl-p-phenylnenediamine (HPPD), polymerized 2,2,4-trimethyl-1,2-dihydroquinoline (TMDQ), paraffin wax as antidegradants, and processing aid like Structol 40MS on paraffinic oil from SBR vulcanizates were also studied. The type of low or high PCA was identified by the relative abundance of absorbance at the aromatic substitution patterns of 864, 810, and $754cm^{-1}$ and at the paraffinic or naphthenic pattern of $721cm^{-1}$.

• Journal of The Korean Association For Science Education
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• v.30 no.1
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• pp.42-53
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• 2010

Identifying students' misconceptions by teachers is the primary step in using constructivist teaching strategies. We investigated how secondary science teachers were aware of students' misconceptions about the particulate nature of matter and analyzed the total number of differences of predicted misconceptions by their background variables. We also investigated how they addressed students' misconceptions in their instruction, and how necessary they thought it was to identify students' misconceptions for teaching science concepts. A survey was administered to 87 science teachers at 28 middle schools in Seoul. Teachers' predictions were compared with the misconceptions of 240 seventh-grade students. The teachers, as a group, identified almost all the misconceptions held by the students. However, they were unable to predict which types of misconceptions were more frequent. The total number of misconceptions predicted by the teachers who had careers of less than 10 years, possessed Master's degrees, or majored in chemical education was significantly higher. Although most teachers stated that knowing students' misconceptions was needed for their instruction, they rarely and simply addressed them in their instructions. Many techers faced misconceptions in classroom activities, and only few teachers found them through publications relating to students' misconceptions, teacher preparation courses and/or in-service training programs. Educational implications are discussed.

• Food Science and Preservation
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• v.18 no.6
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• pp.836-843
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• 2011

The purpose of this study was to develop a functional hasuo (Polygoni Multiflori Radix) muffin prepared via the replacement of sucrose (SM) with oligosaccharide (fructooligosaccharide, isomaltooligosaccharide, galactooligosaccharide). The fructooligosaccharide-added hasuo muffin showed the highest weight while the volume and specific volume were lower in the oligosaccharide-added group than in the sucrose-added sample. The pH of the sucrose-added sample was higher than that of the oligosaccharide-added sample. The lowest lightness value was found in the sucrose-added sample, but the highest redness and yellowness values were found in the sucrose-added sample. The springiness and cohesiveness were highest in the fructooligosaccharide-added sample. The DPPH-radical-scavenging activity of the hasuo muffin including sucrose was 38.67, while that including the oligosaccharide group ranged from 42.87 to 65.95. In the sensory evaluation of the hasuo muffin, the fructooligosaccharide-added sample obtained the highest score in after-swallow, flavor, taste, and texture. The hasuo muffin with fructooligosaccharide and isomaltooligosaccharide obtained high scores in overall acceptability. These results suggest that hasuo muffin with fructooligosaccharide and isomaltooligosaccharide have the potential to become commercially successful muffins.