• 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.

• The Korean Journal of Physiology and Pharmacology
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• 제3권2호
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• pp.215-222
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• 1999

Nonylphenol (NP) is a widespread environmental pollutant that has been shown to exert both toxic and estrogenic effects on mammalian cells. As the effects of NP on the reproductive system of adult male vertebrates are virtually unknown, we investigated not only the changes of reproductive hormone secretion in serum after chronic exposure to NP but also, in order to identify the site of its action, the reproductive hormone secretion in serum 48 hours after microinfusion of NP within hypothalamic preoptic area (POA). In the chronic exposure, the luteinizing hormone (LH), follicle stimulating hormone (FSH), and testosterone in serum were decreased but prolactin (PRL) concentrations were increased. The LH, FSH, and testosterone in serum were decreased through the direct infusion of NP into POA, while there was no difference in mean serum prolactin between NP and control groups. These observations suggest that NP as endocrine disruptor has modulatory effects on hypothalamo-pituitary-gonadal axis and that the site of action of NP could be hypothalamic POA.

• Toxicological Research
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• 제32권1호
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• pp.21-33
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• 2016

Dichlorodiphenyltrichloroethane (DDT) is still used in certain areas of tropics and subtropics to control malaria and other insect-transmitted diseases. DDT and its metabolites have been extensively studied for their toxicity and carcinogenicity in animals and humans and shown to have an endocrine disrupting potential affecting reproductive system although the effects may vary among animal species in correlation with exposure levels. Epidemiologic studies revealed either positive or negative associations between exposure to DDT and tumor development, but there has been no clear evidence that DDT causes cancer in humans. In experimental animals, tumor induction by DDT has been shown in the liver, lung, and adrenals. The mechanisms of hepatic tumor development by DDT have been studied in rats and mice. DDT is known as a non-genotoxic hepatocarcinogen and has been shown to induce microsomal enzymes through activation of constitutive androstane receptor (CAR) and to inhibit gap junctional intercellular communication (GJIC) in the rodent liver. The results from our previously conducted 4-week and 2-year feeding studies of p,p'-DDT in F344 rats indicate that DDT may induce hepatocellular eosinophilic foci as a result of oxidative DNA damage and leads them to hepatic neoplasia in combination with its mitogenic activity and inhibitory effect on GJIC. Oxidative stress could be a key factor in hepatocarcinogenesis by DDT.

• 정보보호학회논문지
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• 제22권3호
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• pp.427-438
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• 2012

SCADA(Supervisory Control and Data Acquisition) 시스템은 국가의 중요한 기반 망인 전력, 가스, 상하수도 등을 제어하기 위해 사용된다. 이전의 폐쇄적인 통신 환경과 달리 최근 개방 통신 환경을 사용함에 따라 안전한 통신을 위한 키 관리 기술이 연구되고 있다. 본 논문에서는 SCADA 시스템을 구성하는 MTU(Master Terminal Unit), Sub-MTU, RTU(Remote Terminal Unit)에 각각 페어링을 이용한 ID 기반의 키 관리 방안을 제시한다. 또한, 예상치 못한 사고나 악의적인 공격들로 인하여 장치들의 개인 키가 노출되거나 또는 KMS(Key Management System)의 마스터 키가 노출되었을 경우에도 SCADA의 키 관리 시스템을 복구할 수 있는 방법을 제시한다.

• 한국산업보건학회지
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• 제32권4호
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• pp.302-324
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• 2022

Objectives: The objective of this study is to investigate exposure to occupational carcinogens in the nationwide electronics industries and to establish a strategy for control of occupational carcinogens in South Korea. Methods: We evaluated occupational carcinogens as defined by International Agency for Research on Cancer (IARC) using a nationwide work environment measurement database on the electronics industry in South Korea measured between 2013 and 2017 in accordance with the Occupational Safety and Health Act. Results: The number of occupational carcinogens found in the electronics industry in South Korea were: 20 for IARC Group 1, 14 for Group 2A, and 30 for Group 2B. The occupational carcinogens (Group 1) most frequently exposed were strong-inorganic-acid mists containing sulfuric acid (sulfuric acid), welding fumes, mineral oils (untreated or mildly treated), nickel compounds, silica dust, crystalline substances in the form of quartz or cristobalite, formaldehyde, arsenic and inorganic arsenic compounds, chromium (VI) compounds, trichloroethylene, cadmium and cadmium compounds, vinyl chloride, ethylene oxide, wood dust, beryllium and beryllium compounds, 1,3 butadiene, benzene, and others. Among them, the carcinogens (Group 1) exceeding the acceptable standard were trichloroethylene, formaldehyde, and ethylene oxide. The working environment measurement system as regulated by Occupational Safety and Health Act is not properly assessed and managed for occupational carcinogens in South Korea. A component analysis for all materials used should be set up to practically reduce occupational carcinogens. A ban on the use of occupational carcinogens and the development of alternative materials are needed. The occupational carcinogens below the acceptable standards should be carefully examined and a new standard for exposure needs to be established. Conclusions: The Occupational Safety and Health Act should be improved to identify and monitor occupational carcinogens at work sites. A strategy for occupational safety and health systems should be provided to give direction to workers' needs and right to know.

• 한국치위생학회지
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• 제12권5호
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• pp.953-961
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• 2012

Objectives : The purpose of this study is to examine the infection control practice and performance study on knowledge of dental hygienist between their knowledge and general characteristics. Methods : The subjects in this study are 305 dental hygienists who received local in-service education on December 10, 2011 and February 28, 2012. Results : The infection prevention knowledge and performance are higher as work experience is more (p<.05), as the education level is higher and when they have undergone in-service education (p<.001). Also these are higher when they are working in the dentist at the present (p<.001). The infection prevention practice are different with respect to ages (p<.01), work experience (p<.001), and the highest level of education (p<.01). There are correlations between the infection control practices and knowledge, performance and knowledge. As the practice level is higher, it is shown that the performance is higher (r=.049, p=.01). Conclusions : It would be necessary to develop the systematic and continuous program in infection control education and to build system which makes in-service training for dental hygienists mandatory. These could improve the level of infection prevention knowledge, practice and performance of dental hygienists to prevent the exposure to infection of the people.

• 반도체디스플레이기술학회지
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• 제20권4호
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• pp.119-124
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• 2021

In a situation where Moore's law, which states that the performance of semiconductor integrated circuits doubles every two years, is showing a limit from a certain point, and it is difficult to increase the performance due to the limitations of exposure technology.In this study, a wafer hybrid method that can increase the degree of integration Various research on bonding technology is currently in progress. In this study, in order to achieve rotational precision between wafers in wafer hybrid bonding technology, modeling of θ_z alignment stage and VCM actuator modeling used for rotational alignment, magnetic field analysis and desgin, control, and evaluation are performed. The system of this study was controlled by VCM actuator, capactive sensor, and dspace, and the working range was ±7200 arcsec, and the in-position and resoultion were ±0.01 arcsec. The results of this study confirmed that safety and precise control are possible, and it is expected to be applied to the process to increase the integration.

• 한국인터넷방송통신학회논문지
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• 제17권3호
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• pp.267-274
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• 2017

최근 농업 분야에 IT 기술이 결합되면서 농업자동화 시스템에 대해 많은 연구가 진행되고 있으며, 농작물의 생육환경을 자동으로 조절하는 시스템에 대한 연구도 이들 중 하나이다. 농작물의 병충해로 야기되는 피해를 방제하는 작업은 농민들의 미흡한 방제 효과에 대한 염려 때문에 수동방제나 반자동방제에 의해 수행되고 있다. 이러한 방식은 사람이 유해한 약물에 노출되거나 약제 과다 사용으로 인한 낭비 및 환경오염 등의 문제점이 있으므로 개선이 필요하다. 이러한 문제점을 해결하기 위해 농약제조회사에서 제시하고 있는 권장 농약 살포량을 기준으로 경작면적에 따른 방제량을 계산하여 정량 방제를 가능하게 하는 자동화정량방제시스템을 개발하였다. 개발된 자동화정량방제시스템의 효율성을 확인하기 위해서 수동방제 및 반자동방제의 경우와 비교하여 실험하였다. 실험을 통해서 자동화된 시스템이 약제의 과다 사용을 줄일 수 있었으며, 수동방제에 버금가는 방제효과를 얻어 기존의 방제작업을 대체 할 수 있음을 알 수 있었다.

• 한국환경과학회지
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• 제16권12호
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• pp.1345-1353
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• 2007

The effect of salicylic acid(SA) on antioxidant system and protective mechanisms against UV-B induced oxidative stress was investigated in cucumber(Cucumis sativus L.) leaves. UV-B radiation and SA were applied separately or in combination to first leaves of cucumber seedlings, and dry matter accumulation, lipid peroxidation and activities of antioxidant enzymes were measured in both dose and time-dependant manner. UV-B exposure showed reduced levels of fresh weight and dry matter production, whereas SA treatment significantly increased them. SA noticeably recovered the UV-B induced inhibition of biomass production. UV-B stress also affected lipid peroxidation and antioxidant enzyme defense system. Malondialdehyde(MDA), a product of lipid peroxidation, was greatly increased under UV-B stress, showing a significant enhancement of a secondary metabolites, which may have antioxidative properties in cucumber leaves exposed to UV-B radiation. Combined application of UV-B and SA caused a moderate increase in lipid peroxidation. These results suggest that SA may mediate protection against oxidative stress. UV-B exposure significantly increased SOD, APX, and GR activity compared with untreated control plants. Those plants treated with 1.0 mM SA showed a similar pattern of changes in activities of antioxidant enzymes. SA-mediated induction of antioxidant enzyme activity may involve a protective accumulation of $H_2O_2$ against UV-B stress. Moreover, their activities were stimulated with a greater increase by UV-B+SA treatment. The UV-B+SA plants always presented higher values than UV-B and SA plants, considering the adverse effects of UV-B on the antioxidant cell system. ABA and JA, second messengers in signaling in response to stresses, showed similar mode of action in UV-B stress, supporting that they may be important in acquired stress tolerance. Based on these results, it can be suggested that SA may participates in the induction of protective mechanisms involved in tolerance to UV-B induced oxidative stress.

• 환경생물
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• 제22권1호
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• pp.171-176
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• 2004

비이온성 계면활성제로 많이 쓰이는 알킬페놀류의 하나인 노닐페놀(nonylphenol)이 해산어류에게 미치는 영향을 조사하려고 주요 양식어종인 조피볼락에게 복강주사로 10 및 25 mg $kg^{-1}$을 1회 투여하였다. 한편 용제인 DMSO만을 주사한 sham구를 설정하여 비교하였다. 주사 후 7일간 간중량지수(hepatosomatic index)의 변화를 조사하였고, 또한 간장 미크로좀 중 대표적인 약물대사효소인 cytochrome P450 (CYP) 농도와 ethoxyresorufin deethylase (EROD) 활성의 변화도 측정하였다. 그 결과, 고농도(25 mg $kg^{-1}$) 주사구에서는 HSl가 감소하였는데, 이것은 NP가 간장에 독성이 있다는 것을 보여준다. 한편, 약물대사효소 중 CYP 농도는 유도되었지만 EROD 활성은 저해되는 경향을 보였다. 이번에 주사한 농도는 우리나라 연근해 해수 중의 NP 농도에 비해 매우 높은 수준이지만, 본 실험에서는 NP가 조피볼락에 게간장 독성을 보였고, 간장의 약물대사효소에도 영향을 미친다는 것을 확인할 수 있었다.