• 한국의상디자인학회지
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• 제4권3호
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• pp.9-15
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• 2002

Compared with synthetic dyes, natural dyes have inferior colorfastness as a result of the exposure of the material to any environment that may be encountered during the processing, testing, storage, display or use of the dyed materials. Especially, colors on fabrics fade excessively after washing. Therefore, it is problem to infer the historic textiles with natural-dyed fabrics. The object of this study is to analyse the factors affected to colorfastness and color change during washing. In experimental, fifteen natural dyes were dyed by the Korean traditional dyeing methods onto natural fiber fabrics: cotton, silk, ramie, and flex. Total 49 dyed fabrics in combination with dyes and fibers were used for the specimen. The Launder-Ometer was used for evaluating the effects of exposure to repetitive washing from 1 to 20 washing cycles (KS K 0430). Color difference(ΔE) in the CIEL＊A＊B＊ color-order system were determined by spectrophotometer at 100 bserver. Washing caused significant changes in the color of natural-dyed fabrics. The degree and nature of color changes on the fabrics were dependent on the combination of fiber and the dye type used. The groups of violet(Lithospermum erythrorhizon Sieb.et Zucc) and black color(Ailanthus altissima Swingle, Phus trichocarpa Miq) yielded excellent colorfastness to repetitive washing. The group of indigo blue color(Polygonum tinctorium Lour.) was also very resistant to color change in washing except silk. Whereas the dye groups of Red, Yellow, Orange, Brown colors indicated greatest changes in color, particularly Carthamus tinctorius L.

• Earthquakes and Structures
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• 제6권2호
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• pp.127-140
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• 2014

Laminated rubber bearing is very popular base isolation of earthquake engineering pertaining to the passive structural vibration control technologies. Rubber used in fabricating NRB and LRB can be easily attacked by various environmental factors such as oxygen, heat, light, dynamic strain, and organic liquids. Among these factors, this study carried out thermal aging test to investigate the effect of thermal aging on the mechanical properties of laminated rubber bearings in accelerated exposure condition of $70^{\circ}C$ temperature for 168 hours. The compressive-shear test was carried out to identify the variation of compressive and shear properties of the rubber bearings before and after thermal aging. In contrast to tensile strength and elongation tests, the hardness of rubber materials showed the increasing tendency dependent on exposure temperature and period. Based on the test results, the property changes of rubber bearing mainly aged by heat are quantitatively presented.

• 한국환경보건학회:학술대회논문집
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• 한국환경보건학회 2006년도 Perspectives of Evironmental Health Issues in Asia-Pacific Region
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• pp.90-110
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• 2006

In the natural course of events, most human exposure to MeHg is through fish/shellfish consumption. The methylmercury exposure levels depends on the amount and species of fish/shellfish consumed daily. The developing brain in the late gestation period is known to be most vulnerable. Further, more methylmercury accumulates in the fetuses than in mothers. Therefore, efforts must be made to protect the fetuses from the risk of methylmercury, especially in populations which consume a lot of fish/shellfish.

• Asian-Australasian Journal of Animal Sciences
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• 제29권8호
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• pp.1188-1196
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• 2016

This study evaluated the risk of Clostridium perfringens (C. perfringens) foodborne illness from natural and processed cheeses. Microbial risk assessment in this study was conducted according to four steps: hazard identification, hazard characterization, exposure assessment, and risk characterization. The hazard identification of C. perfringens on cheese was identified through literature, and dose response models were utilized for hazard characterization of the pathogen. For exposure assessment, the prevalence of C. perfringens, storage temperatures, storage time, and annual amounts of cheese consumption were surveyed. Eventually, a simulation model was developed using the collected data and the simulation result was used to estimate the probability of C. perfringens foodborne illness by cheese consumption with @RISK. C. perfringens was determined to be low risk on cheese based on hazard identification, and the exponential model ($r=1.82{\times}10^{-11}$) was deemed appropriate for hazard characterization. Annual amounts of natural and processed cheese consumption were $12.40{\pm}19.43g$ and $19.46{\pm}14.39g$, respectively. Since the contamination levels of C. perfringens on natural (0.30 Log CFU/g) and processed cheeses (0.45 Log CFU/g) were below the detection limit, the initial contamination levels of natural and processed cheeses were estimated by beta distribution (${\alpha}1=1$, ${\alpha}2=91$; ${\alpha}1=1$, ${\alpha}2=309$)${\times}$uniform distribution (a = 0, b = 2; a = 0, b = 2.8) to be -2.35 and -2.73 Log CFU/g, respectively. Moreover, no growth of C. perfringens was observed for exposure assessment to simulated conditions of distribution and storage. These data were used for risk characterization by a simulation model, and the mean values of the probability of C. perfringens foodborne illness by cheese consumption per person per day for natural and processed cheeses were $9.57{\times}10^{-14}$ and $3.58{\times}10^{-14}$, respectively. These results indicate that probability of C. perfringens foodborne illness by consumption cheese is low, and it can be used to establish microbial criteria for C. perfringens on natural and processed cheeses.

• 생명과학회지
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• 제27권3호
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• pp.339-345
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• 2017

Carotenoid는 천연 지용성 색소이며, 세균, 조류, 식물 등이 생산한다. 세계 시장의 대부분을 차지하는 합성 염료의 대안으로서 현재는 조류나 세균, 갑각류 등의 원료로부터 아스타잔틴의 생산, 정제, 이용이 주목 받고 있다. 이 연구는 UV와 EMS를 이용하여 P. haeundaensis의 돌연변이를 유도하고, 결과적으로 astaxanthin을 과잉 생산하는 돌연변이주를 선별하고 특성을 확인하기 위해 다양한 배양 및 영양 조건을 이용하여 astaxanthin 생산량을 확인하였다. 실험 결과 UV 조사 시간이 증가하거나, EMS 농도가 증가할수록 균주의 생존율이 감소하였다. Astaxanthin 과잉 생산 돌연변이 균주의 경우 400 mM EMS와 UV 20분을 순차적으로 처리한 방법에서 선별된 변이주가 가장 높은 astaxanthin 생산량을 보이는 것을 확인하였으며, 이 균주의 이름을 PUE로 명명하였다. PUE의 최적 배양 조건은 $25^{\circ}C$, pH 7-8, 3% NaCl이며, 1% raffinose, 3% potassium nitrate 첨가 시 astaxanthin 생산량이 증가하는 것으로 밝혀졌다. PUE에서는 wild type 균주에 비해 astaxanthin 생산량이 1.58배 증가함을 확인할 수 있었다. 본 연구의 실험 결과, 돌연변이 유도에 의해 선별된 변이주는 astaxanthin의 산업적 생산에 활용 가능한 후보가 될 수 있을 것으로 사료된다.

• 한국치위생학회지
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• 제9권2호
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• pp.111-124
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• 2009

This study analyzes through the review of literature and laws the exposure time, clinical frequency, and radiation exposure of intraoral and extraoral radiography as well as of panoramic radiography performed by dental hygienists in dental clinics, compares the dental radiology curriculums of radiological science and dental hygiene departments, and proposes the expansion of dental hygienists' radiography operations. The radiology curriculums were compared between the radiological science and dental hygiene departments of colleges. For new analysis by radiography for dental diagnosis, the exposure time, radiation absorbed dose, effective dose, and number of days of natural radiation were compared by the type of oral radiation films and radiographical techniques proposed by domestic and international studies. The exposure time of panoramic radiography is 15 seconds and it takes about two minutes for completion, whereas the exposure time of the standard radiography is 0.2~0.8 seconds and it takes 10 times longer for completion of the radiography of full mouth than the panoramic radiography. The standard radiography can cause distortions of radiation at severely curved parts of dental arch and palatopharyngeal reflex. However, panoramic radiography can be performed even for lock jaw patients, causes less inconvenience to patients and is much simpler than the standard radiography. The percentage of dental clinics where radiography is performed by dental hygienists was 92.0%, and the percentage of standard film radiography by dental hygienists was 98% whereas the percentage of panoramic radiography by dental hygienists was 92%. For the absorbed dose which is an indicator of radiation exposure, the When the effective dose which is an indicator of the danger of radiation exposure was converted to the number of days of natural radiation, it was 3.3 days for panoramic radiography, but 13.9 days for the full mouth standard radiography by bisecting angle technique which was 4.2 times longer than the panoramic radiography. There were two colleges that had a dental radiology course with two credits in the departments of radiological science. The credits for dental radiology courses in the department of dental hygiene ranged varied by college, ranging from 3 to 8; on average, the theory course was 2.2 credits and the practice course was 2.02 credits. To summarize the above results, the percentage of dental clinics where panoramic radiography is performed by dental hygienists under the guidance of dentists is high. Panoramic radiography has become an essential facility for dental clinics. It is faster than standard film radiography and less dangerous due to low radiation exposure. Panoramic radiography is a simple mechanical job that does not require training of oral radiography by radiotechnologist. Because panoramic radiography is one of major operations which must be performed at all times in dental clinics, it must be designated as intraoral technique rather than extraoral technique, or legalized for inclusion in the scope of operations of dental hygienists.

• BMB Reports
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• 제35권4호
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• pp.353-357
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• 2002

Singlet oxygen ($^1O_2$) is highly reactive form of molecular oxygen that may harm living systems by oxidizing critical cellular macromolecules. The oxyR gene product regulates the expression of the enzymes and proteins that are needed for cellular protection against oxidative stress. In this study, the role of oxyR in cellular defense against a singlet oxygen was investigated using Escherichia coli oxyR mutant strains. Upon exposure to methylene blue and visible light, which generates singlet oxygen, the oxyR overexpression mutant was much more resistant to singlet oxygen-mediated cellular damage when compared to the oxyR deletion mutant in regard to growth kinetics, viability and protein oxidation. Induction and inactivation of major antioxidant enzymes, such as superoxide desmutase and catalase, were observed after their exposure to a singlet oxygen generating system in both oxyR strains. However, the oxyR overexpression mutant maintained significantly higher activities of anticxidant enzymes than did the oxyR deletion mutant. These results suggest that the oxyR regulon plays an important protective role in singlet oxygen-mediated cellular damage, presumably through the protection of antioxidant enzymes.

• 한국방사선학회논문지
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• 제11권5호
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• pp.321-328
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• 2017

D-Shuttle (Chiyoda Technol Corporation, Tokyo, Japan) 선량계를 이용하여 개인피폭관리 및 자연방사선량의 모니터링을 위한 기초자료를 제공하는데 연구의 목적이 있다. D-Shuttle을 이용하여 선량을 산출하였다. 선량보고서에서 400 일 노출되었을 때에 1.346 mSv 이었고, 연간선량 (annual dose per year)은 1.228 mSv/year, 평균시간선량 (average dose per hour)은 $0.014{\mu}Sv/hr$ 이었다. 국내의 개인 외부피폭선량 (1.295 mSv/year =Korea average natural individual external dose), 국내의 연간부가선량 (additional dose per year)은 -0.0663 mSv/year 이다. D-Shuttle은 방사선모니터링을 위한 개인선량계로 방사선의 검출성능 우수한 기능, 실시간 방사선 피폭관리, 방사선 작업의 경보 기능, 효율적이고 사용이 편리한 개인 방사선선량의 피폭관리로 ALARA에 매우 유용한 선량계로 사용할 수 있다. 방사선작업종사자와 지역주민의 방사선모니터링 측정기기로 병원, 산업, 의료현장, 원전사고 지역과 비파괴 분야의 위험한 지역에서 방사선모니터링으로 활용될 수 있다.

• 콘크리트학회논문집
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• 제24권1호
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• pp.53-60
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• 2012

이 연구의 목적은 자연모래를 사용한 콘크리트(NSC)와 부순모래를 사용한 콘크리트(CSC)의 고온 하에서의 물리, 역학적인 특성을 조사하는 것이다. 시험체를 $23^{\circ}C$에서 $800^{\circ}C$ 범위에 노출시켜 육안검사와 중량손실을 측정하였으며, 압축강도 시험과 할렬 인장강도 시험을 수행하였다. 그 결과 중량손실률은 노출 온도가 증가할수록 감소하였으며, NSC와 CSC의 감소율은 비슷하였다. 압축강도, 할렬 인장강도와 탄성계수 또한 노출온도가 증가할수록 감소하였다. NSC의 잔존 압축강도는 $200^{\circ}C$와 $400^{\circ}C$에서 CSC보다 급격히 감소했으며, NSC의 잔존 할렬 인장강도 또한 $200^{\circ}C$에서 CSC 보다 급격하게 감소했다. 하지만 CSC와 NSC 공히 $800^{\circ}C$에 노출되었을 때는 비슷한 잔존강도를 나타내었다.

• 한국환경보건학회지
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• 제42권1호
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• pp.61-70
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• 2016

Objectives: The purpose of this study is to determine the exposure risk to tattoo components by analyzing skin absorption using the in vitro method. Tattoos are commonly used for cosmetic purposes, and the skin of not only the operator but of the people who are undergoing the cosmetic procedure is continuously exposed to hazardous chemicals. Methods: Skin permeation risk determination was conducted by the in vitro Franz diffusion cell method according to the ingredient types of tattoo dyes, such as volatile organic compounds (VOCs), non-volatile organic compounds and heavy metals, using hairless mouse full skin and human cadaver epidermis. Results: The major components with good skin penetration for each type of tattoo dye ingredient were clarified. Among the tatto dye ingredients, 1,2-Dichlorobenzene, Zn, Al, Pb and Ti showed good skin penetration. Most of the skin transmission rates were higher in hairless mouse full skin than in human cadaver epidermis. Conclusion: A possible exposure risk to hazardous substances in tattoo dyes was confirmed from this study. These results are expected to provide a positive contribution to the establishment of management regulations for tattoo dyes.