• Toxicological Research
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• 제21권2호
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• pp.99-105
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• 2005

Photo-mutagenic compounds have been known to alter skin cancer rates by acting as initiators or by affecting subsequent steps in carcinogenesis. The objectives of this study are to investigate the utility of photo-chromosomal aberration (photo-CA) assay for detecting photo-clastogens, and to evaluate its ability to predict rodent photocarcinogenicity. Photo-CA assay was performed with five test substances that demonstrated positive results in photo-carcinogenicity tests: 8-Methoxypsoralen (photoactive substance that forms DNA adducts in the presence of ultraviolet A irradiation), chlorpromazine (an aliphatic phenothiazine an alpha-adrenergic blocking agent), lomefloxacin (an antibiotic in a class of drugs called fluoroquinolones), anthracene (a tricyclic aromatic hydrocarbon a basic substance for production of anthraquinone, dyes, pigments, insecticides, wood preservatives and coating materials) and Retinoic acid (a retinoid compound closely related to vitamin A). For the best discrimination between the test substance-mediated genotoxicity and the undesirable genotoxicity caused by direct DNA absorption, a UV dose-response of the cells in the absence of the test substances was firstly analyzed. All 5 test substances showed a positive outcome in photo-CA assay, indicating that the photo-CA test is very sensitive to the photo-genotoxic effect of UV irradiation. With this limited data-set, an investigation into the predictive value of this photo-CA test for determining the photo-carcinogenicity showed that photo-CA assay has the high ability of a test to predict carcinogenicity. Therefore, the photo-CA test using mammalian cells seems to be a sensitive method to evaluate the photo-carcinogenic potential of new compounds.

• 공업화학
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• 제31권1호
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• pp.61-66
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• 2020

본 연구에서는 압착·코팅방식 촉매 제조 공정에 첨가제로 사용되는 콜로이드 실리카의 특성이 제조된 촉매의 성능 및 열적 안정성에 미치는 영향을 연구하였다. 이를 위해 4종의 콜로이드 실리카를 대상으로 실리카 형상 및 크기, 비표면적 및 기공특성, 성분 등을 분석하였으며 해당 콜로이드 실리카를 적용하여 제조한 V₂O₅/TiO₂ 촉매의 특성 평가 및 NOx 전환율에 대한 연구를 수행하였다. 콜로이드 실리카를 이용하여 제조한 촉매의 특성은 적용한 콜로이드 실리카의 특성에 따라 달라지며, 특히 콜로이드 실리카 내 피독물질 함량은 촉매 성능에 직접적인 영향인자인 것으로 분석되었다. 또한 콜로이드 실리카 내 실리카 함량이 높을수록 촉매의 열안정성과 성능이 향상되는 것으로 나타났다.

• International Journal of Oral Biology
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• 제41권4호
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• pp.253-262
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• 2016

Streptococcus mutans (S. mutans) is one of the most important bacteria in the formation of dental plaque and dental caries. S. mutans adheres to an acquired pellicle formed on the tooth surface, and aggregates with many oral bacteria. It initiates plaque formation by synthesizing glucan from sucrose, which is catalyzed by glucosyltransferases. Propolis is a resinous mixture produced by honeybees, by mixing saliva and beeswax with secretions gathered from wood sap and flower pollen. Bees prevent pathogenic invasions by coating the propolis to the outer and inner surface of the honeycomb. Propolis has traditionally been used for the treatment of allergic rhinitis, asthma and dermatitis. We investigated the inhibitory effects of propolis ethanol extract on biofilm formation and gene expression of S. mutans. The biofilm formation of S. mutans was determined by scanning electron microscopy (SEM) and safranin staining. We observed that the extract of propolis had an inhibitory effect on the formation of S. mutans biofilms at concentrations higher than 0.2 mg/ml. Real-time PCR analysis showed that the gene expression of biofilm formation, such as gbpB, spaP, brpA, relA and vicR of S. mutans, was significantly decreased in a dose dependent manner. The ethanol extract of propolis showed concentration dependent growth inhibition of S. mutans, and significant inhibition of acid production at concentrations of 0.025, 0.05, 0.1 and 0.2 mg/ml, compared to the control group. These results suggest that the ethanol extract of propolis inhibits gene expression related to biofilm formation in S. mutans.

• KIEAE Journal
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• 제16권3호
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• pp.113-119
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• 2016

Purpose: In this study, we evaluate the annual energy performance of the detached house which was designed with the aim of zero energy. Method: The experimental house which was constructed in Gonju Chungnam in 2013, is the single family detached house of light weight wood frame with $100m^2$ of heating area. Thermal transmittance of roof (by ISO 10211) and building external walls are designed as $0.10W/m^2K$ and $0.14W/m^2$ respectively and low-e coating vacuum window glazing with PVC frame was installed. Also grid connected PV system and natural-circulation solar water heater was applied and 6kWp capacity of photovoltaic module was installed in pitched roof and $5m^2$ of solar collector in vertical wall facing the south. We analyzed the 2014 annual data of the detached house in which residents were actually living, measured though web-based remote monitoring system. Result: First, as a result, total annual energy consumption and energy production (PV generation and solar hot water) are 7,919kWh and 7,689kWh respectively and the rate of energy independence is 97.1% which is almost close to the zero energy. Second, plug load and hot water of energy consumption by category showed the highest numbers each with 33% and 31%, with following space heating 24%, electric cooker 8%, lighting 3% in order. Hot water supply is relatively higher than space heating because high insulation makes it decreased.

• 콘크리트학회논문집
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• 제14권1호
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• pp.92-99
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• 2002

본 연구는 고로슬래그 미분말의 치환율 변화에 따른 노출 콘크리트의 물리적 성질 및 표면 광택도 특성에 대하여 검토하였다. 실험결과, 고로슬래그 치환율 증가에 따른 공기량 및 유동성은 유사하게 나타났고, 단위용적중량은 저하하였다. 후기재령에서의 압축강도는 고로슬래그의 잠재수경성 반응에 기인하여 증가하였다. 건조수축은 커지는 것으로 나타났다. 노출 콘크리트의 표면 광택도는 W/B가 낮을수록 또한, 표면 도포인 경우 증가하였다. 고로슬래그 미분말의 치환율 증가에 따른 광택도는 고로 슬래그의 공극충전효과 및 백색도에 의하여 증가하였는데, 이때 고로슬래그 미분말의 치환율 10% 증가시 약 7% 정도 증가하였다. 거푸집 종류에 따라서는 아크릴, 치장합판, 철판, 일반합판 순으로 광택도가 우수한 것으로 나타났다.

• 한국환경과학회지
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• 제16권3호
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• pp.299-310
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• 2007

It will be necessary to make proper management plans to preserve the air quality in good level for the public. In order to make these plans, source information and detail emission inventories of the city and near industrial areas should be given. However, lack of the source measurements data makes us more difficult to complete the source inventory. VOC source Inventory could be utilized for the feasibility study to estimate the contribution of VOC sources presenting to the receptor such as residential area. It may give policy maker an idea how to control the air quality, and improve their social environment in the area. This study shows data that measured VOCs concentrations from the local industrial areas in Jeonju during from May 2005 to January 2006. The samples were collected from the near sources in 7 major factories in the industrial park as well as 5 general sources in near city Jeonju area to elucidate the abundances of speciated VOCs and their spacial and temporal distributions depending on source bases. Industrial sources are as follows; chemical, food, paper, wood, metal, non-metal (glass), and painting (coating) industries. The 5 general sources are sampled from tunnel, gasoline gas station, dry cleaning shop, printing (copy) shop, and road pavement working place in urban area. To understand the near source effect at receptor, samples from the 2 receptor sites (one is at center of the industrial complex and the other site is at distance residential area downwind from the center) were collected and analyzed for the comparison to source concentration. The mass contributions of the speciated VOC to total mass of VOCs measured from the different sources and ambient (2 receptors) were presented and discussed.

• 한국환경성돌연변이발암원학회지
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• 제25권1호
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• pp.6-12
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• 2005

Many compounds might become activated after absorption of UV light energy. In some cases, the resulting molecule may undergo further biological reaction of toxicological relevance related especially to the photo-carcinogenicity resulting from photo-genotoxicity. However, no regulatory requirements have been issued with the exception of guideline issued by the Scientific Committee of Cosmetology, Commission of the European Communities (SCC/EEC) on the testing of sunscreens for their photo-genotoxicity. Thus, the objectives of this study are to investigate the utility of photo-Ames assay for detecting photo-mutagens, and to evaluate its ability to predict rodent photo-carcinogenicity. Photo-Ames assay was performed on five test substances that demonstrated positive results in photo-carcinogenicity tests: 8-methoxypsoralen (photoactive substance that forms DNA adducts in the presence of ultraviolet A irradiation), chlorpromazine (an aliphatic phenothiazine an a-adr-energic blocking agent), lomefloxacin (an antibiotic in a class of drugs called fluoroquinolones), anthracene (a tricyclic aromatic hydrocarbon a basic substance for production of anthraquinone, dyes, pigments, insecticides, wood preservatives and coating materials) and retinoic acid (a retinoid compound closely related to vitamin A). Out of 5 test substances, 3 showed a positive outcome in photo-Ames assay. With this limited data set, an investigation into the predictive value of this photo-Ames test for determining the photo-carcinogenicity showed that photo-Ames assay has relatively low sensitivity (the ability of a test to predict carcinogenicity). Thus, to determine the use of in vitro genotoxicity tests for prediction of carcinogenicity,' several standard photo-genotoxicity assays should be compared for their suitability in detecting photo-genotoxic compounds.

• Journal of the Korean Wood Science and Technology
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• 제38권4호
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• pp.333-340
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• 2010

한반도 남부 일대에서 자생하는 황칠나무(Dendropanax morbifera Lev.) 수액으로부터 추출한 천연 도료인 황칠도료(Korean Dendropanax lacquer)는 예로부터 귀중한 예술품이나 투구, 화살, 활 등의 전쟁도구를 찬란한 황금색으로 도장하는데 사용되어 왔다. 경화 후 황금색의 투명한 도막을 형성하여 우수한 색상특성을 지니고 있을 뿐만 아니라 내후성, 내수성, 내식성 등이 우수하여, 보호도장으로써도 훌륭한 가치를 지니고 있다. 그러나 이러한 많은 장점에도 불구하고, 현대적인 여러 적용분야에 사용되지 못하고 있는 이유는 황칠도료의 생산량이 적고, 이로 인하여 가격이 매우 고가이고, 장시간의 경화시간이 소요되는 문제도 큰 원인으로 작용하고 있다. 한편 황칠 내에 광중합이 가능한 conjugated diene을 포함한 모노머가 있으며, 이러한 모노머는 일광 조사 조건등에 의하여 짧은 시간에 단단하고 황금색을 띠는 도막을 형성할 수 있음이 보고된 바가 있다. 따라서 본 연구에 서는 전통적인 황칠도료의 경화방법을 개선하고 경화속도를 촉진하기 위하여, 열개시제를 도입하여 열경화를 촉진하는 방법과 열개시제 및 광개시제를 동시에 도입하고 이중경화(dual curing)에 의해서 경화속도를 촉진하고자 하였다. 이러한 경화 속도 및 경화 거동은 적외선분광분석기(FT-IR)을 이용하여 -C=C- 이중결합 특성피크의 변화를 관찰하거나, 진자경도계(pendulum hardness tester)를 이용하여 표면 경도의 변화를 관찰함으로써 평가하였다. 또한 강체진자물성측정기(RPT)에 spot UV curing 장비를 도입하여 이중경화에 의한 경화 속도 진을 평가하였다. 본 연구의 결과 열개시제에 의하여 열경화가 촉진될 수 있을 뿐만 아니라, 이중경화에 의하여 경화속도를 향상시킬 수 있음을 확인하였다. 또한 이러한 황칠도료 경화 속도 촉진 방법을 활용하여 전통적인 역에만 사용되어온 황칠도료를 현대적인 여러 적용분야에도 확대하여 사용할 수 있는 가능성을 제시하였다.

• 월간산업보건
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• 통권8호
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• pp.4-30
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• 1988

Examination of working environments was conducted to get more detailed data about harmful working environments and to make a contribution to more effective management. Study was carried out on 722 factories located in Taegu city and eight counties in Kyungpook Province, Korea, for a period of one year, from February 1 to December 30, 1986. The total number and proportion of workers exposed to harmful material was 37,697, 45.2% among 83,368 workers. The results according to exposed material were as follows: 1. In the case of noise, proportion of exceeding the 8-hour TLV was 59%, Included were nail-cutting in assembly metal manufacturing industry and weaving process in textile. 2. Dust in mill process of coal manufacturing industries exceeded the TLV of second class of dust at all parts and exceeded the TLV at 6% as a whole.: 3. The fields of industry lower than 70 lux of illumination were storage equipment of food, auto-winder of textile, painting of wood wares and coal mixing, and 44% of all cases was lower than standard. 4. As a result of temperature index investigation(WBGT), about 12% of all sujects exceeded limit value. Included parts were rolling machine and reducing room. 5. In the case of organic solvents, TLV was exceeded at about 8%, The parts exceeded TLV according to materials belonged to this category were as follows. 1) Toluene: adhesive work in assembly metal manufacturing 2) Xylene: printing and paint mixing in chemical manufacturing 3) Methyl ethytl ketone: paint mixing in all parts examined and coating machine partially in chemical manufacturing 4) Methyl isobutyl ketone: printing in chemical manufacturing 5) Acetone: vapor polishing in assembly metal manufacturing 6. Among specified chemical materials, the concentration of HC1 in the air in metal assembly manufacturing factory exceeded TLV. in one of three assembly metal manufacturing examined. Others, such as benzene, acetic acid, formic acid, sodium hydroxide, formalin, ammonia, copper, chromate etc. were lower than TLV in its indoor atmospheric concentration. As a whole, the proportion of exceeding TLV was about 0.8% 7. The concentrations of inorganic lead were lower than TLV in all parts examined. The results of this investigation show the fact that current management of working environments is not satisfactory, and so more active management is needed.

• 보존과학회지
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• 제32권3호
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• pp.377-384
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• 2016

철불의 개금 시 표면에 남아 있는 옻칠 제거 방법에는 물리적인 방법과 화학적인 방법을 사용하고 있으나, 표면 손상 및 약품 사용으로 인한 환경오염, 보존과학자의 건강에도 매우 유해하다. 그래서 본 연구에서는 비접촉식이고 친환경적인 Nd:YAG 레이저를 이용하여 옻칠 제거 실험을 실시하였다. 시편은 크기가 $5{\times}5cm$인 철제(Fe 99.9%)시편 표면을 균일하게 연마한 후 생칠을 도포 횟수를 달리하여 각각 $10{\mu}m$, $20{\mu}m$, $30{\mu}m$의 두께 차이로 제작하였다. 본 실험에서 사용된 레이저기기는 Nd:YAG 레이저로, 적외선 영역의 1064 nm(160~800 mJ)와 가시광선 영역인 532nm(50~350 mJ)의 두 가지 파장 모드를 이용하였다. 실험은 레이저 파장 에너지 조사 횟수 등에 따른 시편 표면의 변화를 조사하였다. 레이저 조사 전 후 표면을 실체현미경과 SEM 관찰, 비접촉 표면 조도 측정기, FT-IR 등을 이용하여 옻칠의 제거 및 잔류 여부를 알아보았다. 분석 결과 1064 nm 파장을 이용하여 $1.0J/cm^2$ 밀도에서 표면 손상 없이 $10{\mu}m$, $20{\mu}m$ 두께의 옻칠이 제거됨을 확인할 수 있었다. 이와 같은 결과를 통해 철불 개금 시 잔류하고 있는 옻칠 제거 방법으로 Nd:YAG 레이저가 효율적임을 본 실험을 통해 알 수 있었다. 향후 금속뿐만 아니라 목칠 가구 등 다양한 재질의 연구가 이루어지면 표면 손상 없이 옻칠을 제거 하는데 효과적으로 활용 가능할 것으로 본다.