• 한국환경보건학회지
• /
• 제42권6호
• /
• pp.450-464
• /
• 2016

Objectives: This study developed and validated reference materials (RMs) to analyze metal compounds in blood. Methods: We referred to KoNEHS (Korea National Environmental Health Survey) to estimate concentrations of blood metals (cadmium, Cd; lead, Pb; mercury, Hg) and applied analytical methods (inductively coupled plasma - mass spectroscopy, ICP-MS, for Cd and Pb; graphite furnace - atomic absorption spectrometry, GF-AAS, for Cd and Pb; and direct mercury analyzer, DMA, for Hg). Homogeneity and stability tests were carried out. In addition, certified values and uncertainties of RMs were calculated through internal and external experiments. All RMs were developed and assessed in various forms according to element, analytical method, and two types of concentration levels high concentration for occupational exposure and low concentration for environmental exposure. Results: All samples showed acceptable homogeneity, except for low concentration of Cd in the GF-AAS method. Short- and long-term stabilities were satisfied by ANOVA testing. In the inter-laboratory comparison, robust medians were lower than the certified values of all RMs (robust median/reference value; $1.301/1.327{\mu}g/L$ for Cd, ICP-MS, low concentration; $3.152/3.388{\mu}g/L$ for Cd, ICP-MS, high concentration; $1.219/1.301{\mu}g/L$ for Cd, GF-AAS, low concentration; $3.074/3.321{\mu}g/L$ for Cd, GF-AAS, high concentration; $14.473/14.516{\mu}g/L$ for Pb, ICP-MS, low concentration; $50.069/50.114{\mu}g/L$ for Pb, ICP-MS, high concentration; $12.881/14.147{\mu}g/L$ for Pb, GF-AAS, low concentration; $47.015/47.591{\mu}g/L$ for Pb, GF-AAS, high concentration; $4.059/4.218{\mu}g/L$ for Hg, DMA, low concentration; $11.474/11.181{\mu}g/L$ for Hg, DMA, high concentration). Conclusion: This study demonstrates procedures for developing and validating RMs for biomonitoring in the field of the environmental health.

• Nutrition Research and Practice
• /
• 제2권4호
• /
• pp.283-288
• /
• 2008

This study was carried out to determine whether a short-tenn zinc supplementation contributes to beneficial changes in glycemic control among type 2 diabetic patients. Seventy-six diabetic subjects and 72 normal adults participated in this study. Subjects were divided into supplemented and control groups. Forty-four diabetic patients and 34 normal subjects were supplemented with 50 mg zinc daily as zinc gluconate for 4 weeks. Zinc status was assessed from fasting plasma levels and urinary excretion. The effects of zinc supplementation on fasting blood glucose, $HbA_{1c}$, insulin, and C-peptide were measured at the beginning of the study and after 4 weeks of supplementation. The changes in glycemic control indicators were compared between diabetic groups, classified by baseline $HbA_{1c}$ levels, and by diabetic duration. At baseline, the incidence of marginal zinc deficiency in the diabetic group, as determined by plasma zinc level, was approximately twice as high as in the normal adult group. The changes of $HbA_{1c}$ concentration, and fasting blood glucose following supplementation were not statistically significant in diabetic subjects. In normal subjects, a significant decrease of $HbA_{1c}$ occurred only in the zinc supplemented group. No significant changes were observed for serum insulin and C-peptide in diabetic as well as normal subjects. However, when the changes were compared by baseline $HbA_{1c}$ level, we found that diabetic subjects with $HbA_{1c}\;{\geq}\;7.5%$ showed significantly improved levels of $HbA_{1c}$ and fasting glucose after Zn supplementation. While such improvement in fasting blood glucose was significant among diabetics with shorter diabetic duration, significant levels of increase in serum insulin and C-peptide were observed in zinc supplemented subjects with longer diabetic duration. Fasting blood glucose was significantly decreased, whereas serum insulin and C-peptide were increased in diabetics with marginal zinc status. Therefore, we suggest that Zn supplementation for a short-term period may improve glycemic control in diabetic patients with higher $HbA_{1c}$ levels and marginal zinc status.

• 한국발생생물학회:학술대회논문집
• /
• 한국발생생물학회 2003년도 제3회 국제심포지움 및 학술대회
• /
• pp.74-74
• /
• 2003

In present study, attempts were made to preserve abalone (Haliotis discus hannai) sperm in liquid form at low temperature, to evaluate the effect of various diluents in short-term storage on sperm, and cryopreservation procedures were optimized for the cryoprotectants as well as freezing rates, in terms of the motility and survival rate, and the ultrastructural changes of sperm after short-term storage and cryopreservation were observed. The abalone sperm reached maximum motility until about 4min after activation. The motility was constant for about 16min, after which it dropped gradually, and about 50min later all motility ceased. Threshold activation of sperm was found in 40% artificial seawater (ASW), and motility increased as the concentration of ASW increased. In Hanks balanced salt solution without calcium (Ca-Free HBSS, 300 and 400 mOsmol/kg) and 10%, 20%, and 30% ASW the sperm was immotile, and motility once again restored incompletely only in HBSS of 300 and 400 mOsmol/kg, 20% and 30% ASW after 100% ASW was added. Sperm motility was extended following 20 days of cold storage only in 70% and 100% ASW. A high motility index of 3.5-4.5 was observed for the first 8 days in 70% and 80% ASW. In other diluents sperm motility was constant less than 10 days, and the motility index was obviously lower than that of sperm in 70% and 100% ASW. After 20 days of cold storage survival rates of 10.2%-20.7% were obtained in ASW and 300 mOsmol/kg HBSS, and that in 400 HBSS (65.3%) was significantly higher than others. The constant period of sperm motility stored in 70% ASW was longer obviously than that in 100% ASW after 6 days of storage, and the time to maximum motility of sperm stored in 70% increased gradually, while the difference in which of sperm in 100% ASW was not significant. The sperm plunged into liquid nitrogen all died except that sperm using 15% glycerol as cryoprotectant restored 10.4% of motility. The highest motility index (3.4) was obtained with 5% glycerol and freezing procedure: $50^{\circ}C$/min from $20^{\circ}C$ to $-80^{\circ}C$.

• 한국환경보건학회지
• /
• 제24권3호
• /
• pp.99-106
• /
• 1998

This study was performed to investigate the bioconcentration of dichlorvos, methidathion and phosalone in zebrafish (brachydanio rerio), red sword tail(Xiphophorus hellieri). The fishes were exposed to 0.05 ppm, 0.01 ppm, 0.50 ppm, one-hundredth concentration of 96-hrs LC$_{50}$ and one-thousandth concentration of 96-hrs LC$_{50}$ and test periods were 3, 5 and 8 days. The deputation rate of each pesticide from the whole body of fish was determined over the 24-hr period after treatment. Obtained results are summerized as follows: In the case of dichlorvos, dichlorvos concentration in zebrafish extract and BCF$_{s}$ of dichlorvos were increased as increasing test concentration. In the case of same experimental concentrations, dichlorvos concentration in zebrafish extract and BCF$_{s}$ of dichlorvos were decreased as proloning test periods, especially dropped after 5days. Dichlorvos concentration in red sword tail extract were increased as increasing test concentration, lyat BCF$_{s}$ in concentration of 0.05 ppm, 0.01 ppm and one-hundredth of 96-hrs LC$_{50}$ were decreased. Methidathion and phosalone concentration in zebrafish extract in zebrafish extract were increased as increasing test concentration, but there was little difference in BCF$_{s}$. In the case of same experimental concentrations, there were little differences in BCF$_{s}$ and concentration in zebrafish extract. In the case of red sword tail, it was impossible to calculate on BCF$_{s}$ data because test concentration was under the detecting limit on GC or test fish were die. Determined deputation rate conatant were highest on dichlorvos, and followed by methidathion, and phosalone. The results of determining depuration rate of these pesticides showed that the high BCF in fish might be due to the slow depuration rate in fish, it is thought to be responsible for vapor pressure, water solubility and partition coefficient. It is suggested that one-hundredth concentration of 96-hrs LC$_{50}$ will be proper test concentration because one-thousundth of LC$_{50}$ was under the detecting limit on GC. Dichlorvos, methidathion and phosalone, organophosphorous pesticides, were examined to their BCF$_{s}$ and depuration rates by means of fish test.

• Asian-Australasian Journal of Animal Sciences
• /
• 제18권6호
• /
• pp.855-860
• /
• 2005

This study was designed to test the effects of changes in energy and protein intake levels on the maternal milk amino acid concentrations over the short-term in lactating mares. Three lactating mares were enrolled for the study 7 weeks after parturition. A low-energy and low-protein diet (LEP) was administered during the first week of the study, followed by administration of a high-energy and high-protein diet (HEP), again for a week (day 1 to day 7), and milk was sampled thrice daily at intervals of 8 h during the study period. The mean amino acid concentrations in the maternal milk, except for those of proline, serine and valine, were significantly higher in the HEP feeding period than during the LEP feeding period (p<0.05). The sum of the concentrations of all the amino acids (TAA) in the maternal milk samples during the HEP and LEP feeding periods was 1,644.9${\pm}$26.9 and 1,542.3${\pm}$36.0 mg/100 g, respectively, the difference between the two was not significant. When the ratio of each amino acid concentration to the TAA in the maternal milk was analyzed, there were significant differences between the HEP and LEP feeding periods for all amino acids, except glycine, serine, alanine and histidine. It was found that the concentrations of glutamic acid+glutamine, serine, threonine, arginine and valine were significantly higher (p<0.05) on day 1 than on day 7 during the LEP feeding period, and there were no such differences during the HEP feeding period. In regard to the effects of changes in the energy and protein intake levels in lactating mares, no changes in milk amino acid concentrations were found following administration of HEP for a week, whereas 7 days of administration of LEP was associated with a decrease in the amino acid concentrations.

• 한국물환경학회지
• /
• 제27권6호
• /
• pp.855-861
• /
• 2011

Short-term effects of current velocity and turbid water on the benthic diatom community and water quality were examined in artificial channel ($20{\times}200{\times}10cm$) with two different experiments. The first and second experiments were consisted of different current velocities such as 1 L/min., and 1, 3, and 6 L/min., respectively. The concentration of turbid water is prepared with loess and fixed at 10 and 20 times of the turbidity of control inflow (10 NTU, LTW), respectively. At experiment 1 (EXP-1), introduction of turbid water increased dissolved oxygen, electric conductivity, pH and turbidity, but there were no differences between low- (100 NTU, MTW) and high-turbid water (200 NTU, HTW). However, experiment 2 (EXP-2) did not change any environmental parameters except dissolved total and inorganic nitrogen like EXP-1. MTW in EXP-1 strongly stimulated the growth of benthic diatom, while both MTW (150 NTU) and HTW (300 NTU) in EXP-2 did not increase or decrease the diatom abundance. Over the study, the dominant species was four, Aulacoseira ambigua, Cyclotella stelligera, Aulacoseira granulata and Achnanthes minutissima. In EXP-1, two highest species in abundance, A. ambigua and A. granulata were highly grown in MTW, while Achnanthes minutissima high in HTW adversely. These results indicate that the introduction of turbid water can play an important role in the shift of water quality and benthic diatom community in stream ecosystem, especially inflow of soil water in low current velocity.

• Safety and Health at Work
• /
• 제1권1호
• /
• pp.51-60
• /
• 2010

Objectives: The level of benzene exposure in the petrochemical industry during regular operation has been well established, but not in turnaround (TA), where high exposure may occur. In this study, the characteristics of occupational exposure to benzene during TA in the petrochemical companies were investigated in order to determine the best management strategies and improve the working environment. This was accomplished by evaluating the exposure level for the workers working in environments where benzene was being produced or used as an ingredient during the unit process. Methods: From 2003 to 2008, a total of 705 workers in three petrochemical companies in Korea were studied. Long- and short-term (< 1 hr) samples were taken during TAs. TA was classified into three stages: shut-down, maintenance and start-up. All works were classified into 12 occupation categories. Results: The long-term geometric mean (GM) benzene exposure level was 0.025 (5.82) ppm (0.005-42.120 ppm) and the short-term exposure concentration during TA was 0.020 (17.42) ppm (0.005-61.855 ppm). The proportions of TA samples exceeding the time-weighted average, occupational exposure level (TWA-OEL in Korea, 1 ppm) and the short-term exposure limit (STEL-OEL, 5 ppm) were 4.1% (20 samples of 488) and 6.0% (13 samples of 217), respectively. The results for the benzene exposure levels and the rates of exceeding the OEL were both statistically significant (p < 0.05). Among the 12 job categories of petrochemical workers, mechanical engineers, plumbers, welders, fieldman and scaffolding workers exhibited long-term samples that exceeded the OEL of benzene, and the rate of exceeding the OEL was statistically significant for the first two occupations (p < 0.05). Conclusion: These findings suggest that the periodic work environment must be assessed during non-routine works such as TA.

• 한국생태학회:학술대회논문집
• /
• 한국생태학회 2002년도 VIII 세계생태학대회
• /
• pp.83-91
• /
• 2002

The Red Queen hypothesis for the advantage of sex predicts that pathogens will evolve by increasing fitness with frequent encounters with specific host genotypes. In this study, BMV population size, measured as an indicator of fitness, was investigated during repeated passages through the same, or different host genotypes of the crop host, Hordeum vulgare (barley). Overall, mean BMV concentration within individual hosts was significantly higher in genetically homogeneous compared to heterogeneous host passage lines. In addition, BMV populations, passaged through a specific host variety, showed higher growth in that host variety compared to BMV passaged through varying varieties. These results supports the Red Queen hypothesis. However, the decrease in viral populations during passages contradicts the Red Queen. Nevertheless, the results found here show that even under simplified conditions, pathogens do not evolve in simple, predictable ways. Constraints on pathogen evolution may lead to counterintuitive results.

• The Korean Journal of Ecology
• /
• 제25권4호
• /
• pp.217-225
• /
• 2002

The Red Queen hypothesis for the advantage of sex predicts that pathogens will evolve by increasing fitness with frequent encounters with specific host genotypes. In this study, BMV population size, measured as an indicator of fitness, was investigated during repeated passages through the same, or different host genotypes of the crop host, Hordeum vulgare (barley). Overall, mean BMV concentration within individual hosts was significantly higher in genetically homogeneous compared to heterogeneous host passage lines. In addition, BMV populations, passaged through a specific host variety, showed higher growth in that host variety compared to BMV passaged through varying varieties. These results supports the Red Queen hypothesis. However, the decrease in viral populations during passages contradicts the Red Queen. Nevertheless, the results found here show that even under simplified conditions, pathogens do not evolve in simple, predictable ways. Constraints on pathogen evolution may lead to counterintuitive results.

• 한국해안·해양공학회논문집
• /
• 제34권3호
• /
• pp.47-57
• /
• 2022

본 연구에서는 진해만의 단일 정점 장기 모니터링 자료를 사용하여 LSTM 모형을 이용한 DO 농도 예측 및 결정 트리 모형을 이용한 빈산소수괴 발생 예측 연구를 수행하였다. LSTM을 이용한 DO 농도 예측 결과, Hidden node의 수가 증가할수록 모형의 복잡도가 증가하여 많은 Epoch을 요구하는 모습을 보였으며, 예측 시간 간격이 증가할수록 긴 Sequence length에서 높은 정확도를 보였다. 결정 트리를 이용한 빈산소수괴 발생 예측 결과, 30 day 예측에서 빈산소수괴 미발생 예측 정확도는 6 6 .1%로 발생 예측 정확도의 37.5%보다 상대적으로 높게 나타났다. 이는 결정 트리 모형이 DO 농도를 관측값보다 고평가하여 나타난 결과로 판단된다.