• 대한안전경영과학회지
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• 제11권1호
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• pp.67-73
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• 2009

The goal of this study was to assess the level of vibration in an walking-type cultivator, and to provide a basic information to manage the vibration exposure for farmers. The latent periods of vibration-induced white finger (VWF) were assessed through analyzing the vibration levels and frequency characteristics. Also, vibration acceleration levels based on the daily vibration exposure duration was suggested. The latent periods of vibration-induced white finger were assessed by ISO 5349 method. The latent periods were 4.5 and 10.1 years at 10% and 50% of farmer group, respectively. Also, under ACGIH (American Conference of Governmental Industrial Hygienists) standard, daily vibration exposure duration at 6.7 m/s2 of vibration acceleration has to be less than 4 hours. Therefore, education that maximum working hours should be less than 4 continuous hours is necessary for the operators of walking-type cultivators.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2022년도 봄 학술논문 발표대회
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• pp.93-94
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• 2022

The presence of chloride (Cl-) ions in environments causes localized corrosion resulting decrease the durability of the structures. In this study, 5% Mg containing Al alloys (Al-5Mg) wire used vis-à-vis compared its corrosion resistance with pure Al in 3.5wt.% NaCl solution with exposure periods. Initially both wires exhibited identical open circuit potential (OCP) attributed to the presence of native oxide film on the surface but with the exposure periods it shifted towards active direction owing to the dissolution of oxide film. The pure Al continuously shifted the OCP towards active direction while Al-5Mg shows stabilization of OCP after 8 days of exposure. The OCP of Al-5Mg is slightly higher compared to pure Al wire owing to the activeness of Mg. The total impedance of the Al-5Mg alloy is almost three times greater than pure Al with exposure periods in 3.5 wt.% NaCl solution. It might be formation of Al-Mg LDH (layered double hydroxide) thin film onto the surface.

• Fisheries and Aquatic Sciences
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• 제7권3호
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• pp.115-121
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• 2004

Experiments were carried out to investigate Cd accumulation, elimination and cell response in juvenile rockfish (Sebastes schlegeli) exposed to sub-chronic dietary Cd (0, 0.5, 5, 25 and 125 mg/kg) for 60 days and depuration periods of 30 days. Cd accumulation in the kidney of cock fish increased with exposure periods and concentrations for the 60 days of dietary Cd exposure. After the end of the dietary Cd exposure, Cd accumulation values in the kidney were $52.9{\pm}9.94\;{\mu}g/g$ and $90.6{\pm}15.7\;{\mu}g/g$ for those exposed to 25 mg/kg and 125 mg/kg Cd, respectively. The accumulation factors increased with the exposure period in the kidney. Cd elimination in the kidney of rockfish did not vary significantly and remained constant after the cessation of the dietary Cd exposure. In the primary exposure periods, the effect of kidney tissue in the rockfish exposed to dietary Cd was observed the swelling of capillary of the glomerulus. In addition, there was also hydropic swelling within the pyknotic nuclei, some of hyaline droplet accumulation and the microvilli showed a positive reaction to alcian blue in the tubular cells. While exposure time and concentrations were increased, there was a lot of hyaline droplet accumulation and the microvilli showed a positive reaction to alcian blue in the tubular cells. Fused renal tubule and its necrosis were observed after 60 days at l25 mg/kg.

• 농업과학연구
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• 제50권4호
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• pp.941-952
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• 2023

The metabolites of agrichemicals, such as organophosphorus pesticides, are known to be more hazardous than their parent pesticides. 3,5,6-trichloro-2-pyridinol (TCP) is a major degradation product of chlorpyrifos, one of the organophosphate insecticides widely used in agriculture. In vivo or in vitro exposure to chlorpyrifos has been known to interfere with male reproductive functions, leading to reduced fertility in mammals. Therefore, this study was performed to examine the changes in the fertilization competence of boar spermatozoa exposed to TCP. Sperm samples were subjected to varying concentrations of TCP (10, 50, 100, 200 µM) and different periods of incubation. Sperm motility, motion kinematics, viability, acrosome integrity, intracellular reactive oxygen species (ROS) production, and gene expression levels (ODf2, ZPBP2, AKAP3 and AKAP4) were evaluated after exposure of the sperm to TCP. A significant dose-dependent reduction in motility was observed in sperm samples incubated with TCP compared to the controls after both incubation periods. Sperm viability was significantly decreased in samples incubated with 50, 100, and 200 µM TCP in both incubation periods. A significantly lower percentage of normal acrosomes and gene expression levels were observed in sperm samples exposed to 50, 100, and 200 µM TCP after both incubation periods, compared to the controls. There was a significant increase in the ROS production in spermatozoa incubated with 100 - 200 µM TCP after both incubation periods. Consequently, the direct exposure of boar spermatozoa to TCP interferes with sperm functions and leads to decreased fertilization. In order to identify and address the various causes of reproductive decline, the impact of chemical metabolites needs to be discussed in depth.

• 농업과학연구
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• 제49권2호
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• pp.307-316
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• 2022

The misuse of pesticides has resulted in environmental pollution, which directly or indirectly affects all life on earth. Chlorpyrifos is a chlorinated organophosphorus pesticide that is commonly used in agriculture. The aim of this study was to investigate the effects of chlorpyrifos on the fertilization function of boar spermatozoa. Sperm samples from boars were subjected to varying concentrations of chlorpyrifos from 10 to 200 µM for two incubation periods, 30 min or 2 hrs. The boar spermatozoa were then evaluated for motility, motion kinematics, viability, acrosome integrity, chromatin stability, and generation of intracellular reactive oxygen species (ROS). There was a significant percentage reduction in sperm motility and motion kinematic parameters after both incubation periods (p < 0.05). The proportion of viable spermatozoa decreased after incubation for 30 min and 2 hrs in a dose-dependent manner (p < 0.05). A significantly lower percentage of normal acrosomes was observed in spermatozoa exposed to 200 µM chlorpyrifos over both incubation periods, compared to the controls. The damage to sperm DNA was significantly higher when the exposure time to chlorpyrifos was longer. There was a significant increase in the ROS levels in spermatozoa incubated with chlorpyrifos for 2 hrs (p < 0.05). From the results of the present study, it is concluded that direct exposure of boar spermatozoa to chlorpyrifos altered boar sperm characteristics, suggesting potential toxicity that may affect the male reproductive function.

• 대한환경공학회지
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• 제28권8호
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• pp.836-842
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• 2006

서울과 안성에서 소나무 잎 1, 2, 3년생을 채취하여 대기 중 노출기간에 따른 침착특성을 조사하였다. 소나무 잎에 침착된 총 PCBs의 농도는 서울과 안성에서 각각 2,429, 1,198 pg/g dry weight(건조질량)이었다. 소나무 잎에 침착된 PCB homologs의 농도는 염소치환수가 증가할수록 감소하였는데 이는 고분자 PCBs일수록 대기 중에서 입자상 분율이 가스상에 비해 증가하여 식물에 침착되기가 어렵기 때문으로 판단된다. 소나무 잎에 노출된 기간과 총 PCBs의 농도와의 회귀분석 결과, 매우 유의한 결과($R^2>0.94$, p<0.01)를 나타내었는데 이는 대기에 노출되는 기간에 비례하여 소나무 잎에 PCBs가 선형적으로 누적침착 되고 있음을 알 수 있다. 결과적으로 여러 지역에서 노출기간별로 채취한 소나무 잎은 그 지역 대기 중 PCBs의 장기적인 침착 경향을 파악할 수 있는 passive air sampler로 사용가능 할 것으로 판단되었다.

• 한국광학회:학술대회논문집
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• 한국광학회 1989년도 제4회 파동 및 레이저 학술발표회 4th Conference on Waves and lasers 논문집 - 한국광학회
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• pp.193-195
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• 1989

A simple fabrication technique of diffraction gratings with short periods is presented. We can see that the monitoring of diffracted light from photoresist gratings during the development process provides optimum conditions for exposure and development processes. With this technique reproducibility and high quality of diffraction gratings is expected.

• Fisheries and Aquatic Sciences
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• 제5권4호
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• pp.295-301
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• 2002

Experiments were carried out to investigate the effects of metal interaction on the accumulation and elimination of Cd and Cu in the liver of flounder, Paralichthys olivaceus, exposed to sub-chronic Cd (0, 5, 10, 50, 100 ${\mu}g/L$)/Cu $(10 {\mu}g/L)$ mixture. Cd exposure resulted in an increased Cd accumulation in the liver of flounder for exposure periods and concentration, and Cd accumulation increased linearly with exposure time. Cu accumulation profiles were similar to those of Cd. Cd concentration in the liver significantly decreased at the 10th depuration period and elimination rate was $66.20\%,\;86.22\%$ in 50 and $100 {\mu}g/L$at the end of depuration periods, respectively. Although, Cu elimination was similar to Cd elimination phase, Cd elimination rate was higher than that of Cu. Co-relationship of Cd and Cu have a positive correlation coefficient r=0.8620 (P<0.001) and support the strong relationship between Cd and Cu accumulation. As increase with the Cd exposure concentration, there were significant (P<0.001) differences between Cd and Cu accumulation.

• Fisheries and Aquatic Sciences
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• 제6권4호
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• pp.213-219
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• 2003

Experiments were carried out to investigate the accumulation and elimination changes in the tissue of juvenile rockfish (Sebastes schlegeli) after sub-chronic dietary Cu (0, 50, 125, 250 and 500 mg/kg) exposure for 60 days and depuration for 30 days. The profile of Cu accumulation in the tissue of rockfish was dependent on the exposure periods and Cu concentration. Liver of rockfish is a more important storage tissue than other tissues, and the order of Cu accumulation in tissues was liver > intestine > kidney > gill > muscle. The accumulation factors were increased with the exposure period in gill, intestine, liver, kidney and muscle. An inverse relationship was observed between the accumulation factor and the exposure concentrations in the gill, kidney and muscle. Cu elimination in tissues of rockfish were decreased with periods for the 30 days of depuration except kidney and muscle. The order of Cu elimination in organs during depuration was intestine > liver > gill.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 I
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• pp.433-438
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• 2001

This study is performed to evaluate hand-arm vibration syndrome(HA VS) of the workers in swaging process. Vibration measurement and assessment of human exposure are based on the international standard(ISO 5349). Triaxial acceleration of each operation and exposure time are measured to predict the periods before finger blanching, As results, it is found that acceleration is concerned with the diameter of pipes in swaging process, and also found that combined work is more harmful than a single operation.