• 접착 및 계면
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• 제17권3호
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• pp.89-95
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• 2016

유연한 식품포장필름에 사용되고 있는 드라이 라미네이션용 유성접착제를 대체하기 위해, 고분자 분산제를 사용하여 유화하는 방법으로 수성 감압점착제를 친환경적으로 설계하였다. 유화중합에서 널리 사용하는 저분자량의 계면활성제는 물성의 변수로 작용해 왔다. 본 연구에서는 먼저 용액중합으로 polymeric nano-dispersant (PND)를 제조하고, 이 PND 입자들의 분산제를 micelle seed로 이용하여 core-shell grafted acrylic 점착제를 합성하였다. 이때 입자의 바깥층(shell)과 입자내층(core)의 $T_g$를 달리하여 얇은 필름의 점착조건인 초기접착력과 유지력의 균형을 이루도록 설계하였다. 최적화된 시험군 합성 점착제의 물성을 국내외 제조사에서 개발된 연구시료들과 비교분석하여, 점착제로서의 물성을 검토하였다. 물성 비교 결과, 본 연구에서 설계 합성한 저분자량의 계면활성제를 대체 사용한 고분자 나노분산제 기반 core-shell 점착제가 연포장에 적합한 점착물성을 나타냄을 확인하였다.

• 농업과학연구
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• 제47권3호
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• pp.673-681
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• 2020

Human enteric Adenovirus 41 (HueAdV-41) is a major waterborne virus that causes human gastroenteritis and is classified as a viral group I double-strand DNA virus, Adenoviridae. HueAdV-41 has been detected with the polymerase chain reaction (PCR) in various samples such as ground water. However, the PCR-based diagnostic method has problems such as reaction time, sensitivity, and specificity. Thus, the loop-mediated isothermal amplification (LAMP) assay has emerged as an excellent method for field applications. In this study, we developed a LAMP system that can rapidly detect HueAdV-41 with high specificity and sensitivity. HueAdV-41 specific LAMP primer sets were tested through a specific, non-specific selection and sensitivity test for three prepared LAMP primer sets, of which only one primer set and optimum reaction temperature were selected. The developed LAMP primer set condition was confirmed as 63℃, and the sensitivity was 1 copy. In addition, to confirm the system, a LAMP positive reaction was developed with the restriction enzyme Taq I (T/GCC). The developed method in this study was more specific, rapid (typically within 2 - 3 hours), and highly sensitive than that of the conventional PCR method. To evaluate and verify the developed LAMP assay, an artificial infection test was done with five cDNAs from groundwater samples, and the results were compared to those of the conventional PCR method. We expect the developed LAMP primer set will be used to diagnose HueAdV-41 from various samples.

• 한국환경보건학회지
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• 제39권1호
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• pp.32-42
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• 2013

Objectives: Cryptosporidium, a protozoan parasite, has been recognized as a frequent cause of waterborne disease due to its extremely strong resistance against chlorine disinfection. Although there has as yet been no report of a Cryptosporidium outbreak through drinking water in Korea, it is important to estimate the health risk of Cryptosporidium in water supply systems because of the various infection cases in human and domestic animals and frequent detection reports on their oocysts in water environments. Methods: This study evaluated the annual infection risk of Cryptosporidium in tap water using the quantitative microbial risk assessment technique. Exposure assessment was performed upon the results of a national survey on Cryptosporidium on the water sources of 97 large-scale water purification plants in Korea, water treatment efficacy, and daily unboiled tap water consumption. The estimates of the US Environmental Protection Agency on the mean likelihood of infection from ingesting one oocyst were applied for effect assessment. Results: Using probabilistic methods, mean annual infection risk of Cryptosporidiosis by the intake of tap water was estimated to fall within the range of $2.3{\times}10^{-4}$ to $1.0{\times}10^{-3}$ (median $5.7{\times}10^{-4}$). The risk in using river sources was predicted to be four times higher than with lake sources. With 0.5-log higher removal efficacy, the risk was estimated to be $1.8{\times}10^{-4}$, and could then be lowered by one-third. Conclusions: These estimations can be compared with acceptable risk and then used to determine the adequacy and priority of various drinking water quality strategies such as the establishment of new treatment technology.

• Environmental Analysis Health and Toxicology
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• 제25권3호
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• pp.241-251
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• 2010

Crucian carp (Carassius auratus) has been used as the sentinel species for POPs (Persistent Organic Pollutants) monitoring in aquatic environment. However, there is little information for dioxin toxicity and especially, early life stage toxicity in crucian carp have been never carried out. In this study, we investigated several toxic effects for 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) in fertilized egg obtained by natural fertilization from crucian carp. The embryos at 3 h post-fertilization (hpf) were treated with 0.039, 0.156, 0.625, and 2.5 (${\mu}g/L$) TCDD by waterborne exposure for 60 minutes and changed with fresh water 2 times per day. Fertilized eggs started hatching at 51 hpf and TCDD exposed embryo showed decrease of hatching rate in a dose-dependent manner at 75 hpf. Pericardial edema was continuously observed in larvae exposed to TCDD from hatching start time (51 hpf), followed by the onset of mortality. In addition, AhR-related gene, CYP1A was clearly increased by TCDD in a dose dependent manner. These results indicated that fertilized eggs obtained from crucian carp have the TCDD related gene regulation and a distinct TCDD developmental toxicity syndrome by TCDD exposure. Therefore, we suggested that early life stage test in crucian carp could be used as test methods on dioxins toxicity.

• 상하수도학회지
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• 제23권2호
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• pp.199-205
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• 2009

It is very important to differentiate of DNA derived from live or dead bacteria within mixed microbial communities in aquatic environments. Ethidium monoazide (EMA) is a DNA intercalating agent and the treatment of EMA with strong visible light cleaves the genomic DNA of bacteria. In dead bacterial cells, EMA intercalates into the genomic DNA, induces the cleavage of DNA, and inhibits the PCR amplification. In this study, we developed the EMA-PCR and EMA real-time PCR to detect the DNA derived from viable Escherichia coli (E.coli) in mixed cultures of live and dead E.coli. The treatment of EMA, $50{\mu}g/mL$, and 650 W visible halogen light exposure for 2 minutes cleaved the genomic DNA derived from heat killed E.coli but did not those of live E.coli. EMA-PCR could detect the DNA from live E.coli in mixed culture samples of live and dead E.coli at various ratio and there was no DNA amplification in only dead E.coli cultures. Similar results were observed in EMA real-time PCR. Further studies are needed to develop various EMA-PCR methods to detect viable waterborne pathogens such as Helicobacter pylori, Giardia lamblia, and so on.

• 한국어병학회지
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• 제17권1호
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• pp.67-74
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• 2004

범게, Orithyia sinica 유생을 대상으로 암모니아와 아질산에 대한 생존 및 성장에 관한 실험을 실시하였다. 암모니아 노출 실험구에서 zoea기 유생은 노출 20일후, 대조구가 80%의 생존율을 나타내었지만 10 mg/L 이상의 실험구에서는 37-45%의 생존율을 나타내었고, megalopa기 유생에서도 유사한 경향을 나타내었다. 암모니아가 범게 유생의 성장에 미치는 영향을 조사한 결과, zoea기 유생은 20 mg/L 이상의 농도에서 megalopa기 유생은 50 mg/L 이상의 농도에서 유의한 차이를 나타내었다 (P<0.05). 아질산 노출실험에서는 zoea기 유생과 megalopa기 유생에서 농도와 노출기간에 비례하여 생존율이 감소하였으며, 특히 150 mg/L 이상의 아질산 농도에 노출된 zoea기 유생과 megalopa기 유생은 대조구와 비교하여 유의한 성장 지연을 나타내었다.(P<0.05)

• 접착 및 계면
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• 제8권4호
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• pp.14-22
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• 2007

본 연구에서는 페놀수지의 열안정성 그리고 glass braid/페놀수지 복합재료의 동역학적 열특성에 미치는 유리분말 및 액상 니트릴고무(NBR)의 영향을 열중량분석기와 동역학적 열분석기를 이용하여 조사하였다. 수용성 페놀수지에 충진된 유리분말과 NBR은 페놀수지의 열안정성과 복합재료의 저장탄성률 그리고 tan ${\delta}$ 변화에 중요한 영향을 미쳤다. 유리분말의 충진은 페놀수지의 열안정성을 향상시키는 반면, NBR의 존재는 특정 온도영역에서 페놀수지의 중량감소를 초래하였다. 충진제의 유 무에 따른 페놀수지의 열안정성은 경화온도뿐만 아니라 경화시간에도 의존하였다. 스트립형태의 glass braid/페놀수지 복합재료의 저장탄성률과 tan ${\delta}$의 변화는 유리분말과 NBR이 혼합된 매트릭스의 도입과 경화조건에 의해 크게 영향을 받았다.

• 한국환경보건학회지
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• 제47권6호
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• pp.505-512
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• 2021

Background: The occurrence of environmental disease is known to be associated with chronic exposure to toxic chemicals, including waterborne contaminants, air/indoor pollutants, asbestos, ingredients in humidifier disinfectants, etc. Objectives: In this study, we reviewed toxicological studies related to environmental disease as defined by the Environmental Health Act in Korea and toxic chemicals. We also suggested a direction for future toxicological research necessary for the prevention and management of environmental disease. Methods: Trends in previous studies related to environmental disease were investigated through PubMed and Web of Science. A detailed review was provided on toxicological studies related to the humidifier disinfectants. We identified adverse outcome pathways (AOPs) that can be linked to the induction of environmental diseases, and proposed a chemical screening system that uses AOP, chemical toxicity big data, and deep learning models to select chemicals that induce environmental disease. Results: Research on chemical toxicity is increasing every year, but there is a limitation to revealing a clear causal relationship between exposure to chemicals and the occurrence of environmental disease. It is necessary to develop various exposure- and effect-biomarkers related to disease occurrence and to conduct toxicokinetic studies. A novel chemical screening system that uses AOP and chemical toxicity big data could be useful for selecting chemicals that cause environmental diseases. Conclusions: From a toxicological point of view, developing AOP related to environmental diseases and a deep learning-based chemical screening system will contribute to the prevention of environmental diseases in advance.

• 접착 및 계면
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• 제23권4호
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• pp.137-143
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• 2022

본 연구에서는 신발 및 의류용 접착제로 접착력과 굴곡성이 우수한 폴리우레탄 아크릴레이트 수지를 합성하기 위하여 폴리에스테르 폴리올인 poly(tetramethylene adiphate glycol) (PTAd)와 폴리에테르 폴리올인 poly(tetramethylene ether glycol) (PTMG)를 4,4'-methylene diphenyl diisocyanate (MDI), isophorone diisocyanate (IPDI), 1,4-butandiol (1,4-BD), 2-ydroxyethyl methacrylate (2-HEMA), dibutyl amine (DBA)와 함께 사용하여 폴리우레탄 아크릴레이트를 합성하였으며, 폴리올을 병용한 폴리우레탄 아크릴레이트의 열적·기계적 특성, 접착력 및 굴곡성을 검토하였다. 합성된 폴리우레탄 아크릴레이트의 유리전이온도는 -70~-40 ℃ 범위로 확인되었으며, PTAd 함량이 증가함에 따라 유리전이온도, 분해온도, 인장강도, 접착력 및 내열성이 증가하였고 반대로 신장률, 내수성 및 굴곡성은 감소되었다. 합성된 폴리우레탄 아크릴레이트는 PTAd와 PTMG 비율이 5:5일 때 높은 접착력과 굴곡성을 나타내었다.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2023년도 학술발표회
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• pp.170-170
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• 2023

Providing safe and readily available water is vital to maintain public health. One of the most prevalent methods to prevent the spread of waterborne diseases is applying chlorine injection to the treated water before distribution. During the water transmission and distribution, the chlorine will experience a reduction, which can imply potential risks for human health if it falls below the minimum threshold. The ability to determine the appropriate initial intensity of chlorine at the source would be significant to prevent such problems. This study proposes two methods that integrate hydraulic and water quality modeling to determine the suitable intensity of chlorine to be injected into the source water to maintain the minimum chlorine concentration (e.g., 0.2 mg/l) at each demand node. The water quality modeling employs the first-order decay to estimate the rate of chlorine reduction in the water. The first method utilizes a backtracking algorithm to trace the path of water from the demand node to the source during each time step, which helps to accurately determine the travel time through each pipe and node and facilitate the computation of time-dependent chlorine decay in the water delivery process. However, as a backtracking algorithm is computationally intensive, this study also explores an alternative approach using a water age. This approach estimates the elapsed time of water delivery from the source to the demand node and calculate the time-dependent reduction of chlorine in the water. Finally, this study compares the outcomes of two approaches and determines the suitable and effective method for calculating the chlorine intensity at the source to maintain the minimum chlorine level at demand nodes.