• Journal of Korean Society of Occupational and Environmental Hygiene
• /
• v.19 no.3
• /
• pp.280-287
• /
• 2009

High-tech microelectronics industry is known as one of the most chemical-intensive industries. In Korea, Microelectronics industry occupied 38% of export and 16% of working employees work in microelectronics industry. But, chemical information and health hazards of high-tech microelectronics manufacturing are poorly understood because of rapid development and its penchant for secrecy. We need to investigate on chemical use and exposure control. We Site-visits to 6 high-tech microelectronics manufacturing company which have cleanroom work using over 1,000kg organic solvents (5 semi-conductor chips and its related parts company, 1 liquid crystal display (LCD)). We reviewed their data on chemical use and ventilation system, and measured TVOCs (Total Volatile Organic Compounds) and carbon dioxide concentration. All cleanroom air passed through hepa filters to acheive low particle levels and only 1 cleanroom uses carbon filters to minimize the organic solvents exposures In TVOC screening test, Cleanroom for semi-conductor chips and its related parts company with laminar down flow system (e.g. class 1~100) showed nondetectable level of TVOCs concentration, but Cleanroom for liquid crystal display (LCD) with conventional flow system (e.g. class 1,000~10,000) showed 327 ppm as TVOCs. Acetone concentration in cleanroom for Jig cleaning, LC Injection, Sealing processes were 18.488ppm (n=14), 49.762 ppm (n=15), 8.656 ppm (n=14) as arithmetric mean. Acetone concentration in cleanroom for LCD inspection process was 40ppm (n=55) as geometric mean, where the range was 7.8~128.7ppm and weakly correlated with ventilation rate efficiency(r=0.44, p<0.05). To control organic solvents in cleanrooms, chemical and carbon filters should be installed with hepa filters. Even though their volatile organic compounds concentration was not exceed to occupational exposure limits, considering of entrance limited cleanroom environment, long-term period exposure effects and adverse health effects of cleanroom worker need further reseach.

• Journal of Korean Society of Water and Wastewater
• /
• v.20 no.4
• /
• pp.519-526
• /
• 2006

In this study, the major operating factors in SND(simultaneous nitrification and denitrification) using bioreactor packed with submerged cilia media and granular sulfur such as variation of nitrification rate, organic matter removal efficiency and denitrification efficiency in different DO concentration were mainly evaluated. Synthetic wastewater and actual sewage were used as influent wastewater. Experiment with synthetic wastewater as influent wastewater was divided into three phases with the adjustment of DO concentration. As the results, nitrification efficiency and T-N removal efficiency in the Phase 3(DO 1.0~2.0 mg/L) were 99% and 52.3%, which is significantly greater than those in other two phases. Also, loading rate and denitrification efficiency of SCPGS(Submerged Cilia media Packed with Granular Sulfur) were calculated as $0.44kg\;NO_3^--N/m^3-day$ and 50%, respectively. On the other hand, nitrification rate was decreased from 99% to 64% according to the DO concentration with the variation from 3.0~3.5 mg/L(phase1) to 0.4~0.6mg/L(phase2). Although the nitrification rate was decreased in 64% according to the variation of the DO concentration, T-N removal rate was rapidly increased to 49% by increasing of the denitrification efficiency. Experiment with actual sewage as influent wastewater was carried out to evaluate efficiency of SCPGS in real operation condition of full-scale sewage water treatment plant. At the time, T-N removal rate in this experiment and full-scale wastewater treatment plants were given by 43% and 20%, respectively. The above results indicate that SCPGS can be used as an advanced treatment process for economical efficiency considered.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2004.04b
• /
• pp.38-41
• /
• 2004

The oxidizer plays an important role in the metal chemical mechanical polishing(CMP) slurry. Currently, the oxidizer used in CMP slurry is nearly divided into several kinds such as $Fe(NO_3)_3$, $H_2O_2$, $KIO_3$, and $H_5IO_6$. It is generally known that oxidizer character of $H_2O_2$ is more effective than other oxidizers. In this work, we have been studied the characteristics for the $H_2O_2$ concentration of copper slurry, which can applicable in the recent semiconductor manufacturing process. Also, it plays an important role in the planarization of copper films using copper slurries during micro-electronic device fabrication. In this work, we confirmed that removal rate of Cu/TaN changed by $H_2O_2$ concentration on copper slurry. And we used $KMnO_4$ in the measurement method of $H_2O_2$. In analysis results, we confirmed that the difference of results is large. We thought that the difference was due to organic component existence. So in titration method of $H_2O_2$ concentration, we used $Na_2S_2O_3$ instead of $KMnO_4$ as solution. Consequently, using the titration method, we could calculate correct data reduced error. And $H_2O_2$ concentration has been adjusted to the target concentration of 0.1 wt%.

• Polymer(Korea)
• /
• v.26 no.6
• /
• pp.792-802
• /
• 2002

In this study, hydrogels from mixtures of poly (vinyl alcohol) (PVA)/poly(N-vinylpyrrolidone) (PVP)/glycerin/chitosan were prepared by γ-ray irradiation and the mechanical properties such as gelation, water absorptivity, and gel strength were examined to evaluate the applicability of these for wound dressing. Then PVA:PVP was weight ratio of 6 : 4, the concentration of chitosan was 0.3 wt%, the concentration of glycerin was in the range of 0∼5 wt%t. The solid concentration of PVA/PVP/glycerin/chitosan solution was 15 wt%. Gamma irradiation doses of 25, 35, 50, and 60 kGy were exposed to a mixture of PVA/PVP/glycerin/chitosan to evaluate the effect of irradiation dose. Gel content and gel strength increased as glycerin concentration in PVA/PVP/glycerin/chitosan decreased, and as irradiation dose increased. Swelling degree increased as glycerin concentration in PVA/PVP/glycerin/chitosan increased, and as irradiation dose decreased. The glycerin in PVA/PVP/glycerini/chitosan hydrogel prevented the transformation of shape. These hydrogel dressings had better curing effect than vaseline gauge.

• Physical Therapy Korea
• /
• v.14 no.2
• /
• pp.37-43
• /
• 2007

Electrical acupuncture has been shown to induce hypoglycemic effect in streptozotocin diabetic rats. The Zusanli acupoints have been widely used in traditional Chinese medicine to relieve symptoms of diabetes mellitus. But, the effects of electrical acupuncture stimulation of different frequencies are still unclear. We designed an experiment to investigate the effect of electrical acupuncture of high (100 Hz) and low (2 Hz) frequencies on Zusanli acupoint for 15 minutes in streptozotocin diabetic rats. They were divided into 4 groups, high frequency electrical acupuncture (HFEA group, n=5), low frequency electrical acupuncture (LFEA group, n=5), without any treatment (control group, n=5) and normal group (n=5). After 2 weeks of treatment, the HFEA and LFEA groups had a significantly decreased glucose concentration in serum in comparison to the control group. Additionally, the HFEA group had a significantly decreased glucose concentration in serum compared with the LFEA group. Both the HFEA and LFEA groups had a significantly decreased Immunoglobulin G concentration in serum compared with control group. The LFEA and control groups had a significantly increased cholesterol concentration in serum compared with the normal group, but the HFEA did not have a significantly increased cholesterol concentration. Thus we suggest that electrical acupuncture stimulation at the Zusanli acupoints is effective on hypoglycemic effect and immune function. Overall, the therapeutic effects of electrical acupuncture at 100 Hz was better than effects at 2 Hz.

• Korean Journal of Veterinary Research
• /
• v.51 no.1
• /
• pp.47-53
• /
• 2011

In Korea, groundwater is main water source in livestock farms. Most dairy and cattle farms have constructed their own wells for human drinking and livestock farming. However, these private residential wells have not been controlled by government and also there was scant study about livestock drinking water quality. Therefore this study was to monitor of the livestock farms' groundwater quality in Korea. Water samples were collected at 123 dairy and cattle farms and were analysed forty six substances with quality standard for drinking water approved by the Minister of Environment. Seventy eight (63.4%) of 123 samples failed to drinking water stand a test. The most frequent contaminants were nitrate-nitrogen and microbial. 22.8% (n=28) of samples showed nitrate-N concentration of higher than 10 mg/L meant that can't be used drinking water for human and the Nitrate-N concentration analysed in the range of 0.2 to 61.2 mg/L. All of 78 failed to drinking samples had microbial problems, especially 5.7% (n=7) of samples indicated water could be contaminated by feces. Other contaminants detected were zinc and evaporation residue. Especially detected zinc concentration (32 mg/L) was about ten times higher than standard of zinc (3 mg/L). Regression analysis indicated that groundwater pH did not influence to nitrate-N concentration but the hardness and chloride could affect to nitrate-N concentration in the groundwater. Most livestock farms were adjacent to crop farmland in Korea. This could cause contamination of groundwater with nitrate-N and pesticide that could accumulate livestock product. Moreover Heavy metal such as zinc and copper could be released from a corrosive plated water pipe in livestock farm. Put together, Korea livestock system is indoor, not pasture-based, hence livestock could be exposed to potential contaminated water consistently. Therefore on the basis of these data, appropriate livestock drinking water quality standards should be prepared to keep livestock healthy and their product safe. Further, livestock drinking water quality should be monitored continuously in suitable livestock drinking water standards.

• Journal of Radiation Protection and Research
• /
• v.11 no.2
• /
• pp.104-113
• /
• 1986

The ion exchange behaviour of the $Cs^{+1},\;Sr^{+2},\;and\;Th^{+4}$ in the system of $Cs^{+1},\;Sr^{+2},\;Th^{+4},\;and\;7Cl^{-}-H^{+}$ from Dowex HCR-W2, was examined in the loading and elution processes. $Th^{+4}$ was slowly adsorbed through the entire contact time between resin and solution and $Cs^{+1}\;and\;Sr^{2+}$ were adsorbed fast for the first few minutes of contact time. Because of the strong affinity of $Th^{+4}$, the longer contact time was allowed, the less amount of $Cs^{+1}\;and\;Sr^{2+}$ was adsorbed on the resin. The peak concentration of the resin phase $Cs^{+1}$ in the solution concentration of $Cs^{+1}:Sr^{+2}:Th^{+4}$ in the ratio of 2 : 2 : 1 in normality with total normality of 0.1N was produced at about 4 minutes of contact time and the peak time for $Sr^{+2}$ was 20 minutes. The loaded ions were eluted using hydrochloric acid. The loaded $Cs^{+1}$ was eluted at the low eluent concentration of less than 0.1N with less than 5% contamination of $Sr^{+2}$. The loaded $Th^{+4}$ was eluted at the high eluent concentration of greater than 1N. The best eluent concentration for eluting $Th^{+4}$ was 4N.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.12 no.2
• /
• pp.146-149
• /
• 1983

An experiment was made to investigate the effect of acid and alkali treatments obfserving the amount of nutrients especially calcium(Ca), phosphorus(P), ${\alpha}$-amino nitrogen(${\alpha}$-amino N), and total nitrogen(total-N)which were extracted from beef bone. 0~0.8% acetic acid and 0~0.5% sodium bicarbonate were used for treatment on different levels. The results are as follows; In case of acid treatment, Ca and P contents in bone stock wer observed to increase significantly according to acid concentration. Ca and P contents in bone stock highly incrased especially when the acid concentration was above 0.3%. Ca and P ratio varied from one to two when the acid concentration was below 0.01%. However contents of ${\alpha}$-amino N and total-N increased significantly when acid concentration was above 0.5%. In case of alkali treatment, contents of Ca and P did not increased significantly on all levels of sodium bicarbonate. The content of ${\alpha}$-amino N, however, increased significantly when the alkali concentration was in 0.05% but total-N did not show any variation in amount. These results suggest that acid treatment can give rise to an increase of the amount of nutrients which are extracted from beef bone but alkali treatment does not.

• The Korean Journal of Ecology
• /
• v.28 no.2
• /
• pp.93-98
• /
• 2005

The effects of the presence of a submerged plant, Zizania latifolia, on physico-chemical characteristics, including Eh, pH, and concentrations of nitrogen and phosphorus in the sediments were studied under pot culture condition. It was shown that Eh value at reduced layer of the sediments was higher in the planted pots than in the non-planted. It was also revealed that $NH_4^+-N$ concentration of the sediments in the planted pots was lower than that of the non-planted, which might be due to the uptake by the plants. In contrast, $NO_3^--N$ concentration in the sediment increased in the presence of the plants compared to the non-planted, which might be attributed to oxygen released from the roots to the reduced layer. The concentration of organic phosphorus in the sediments was much higher than that of NAIP at the beginning of the planting experiment. However, at the end of the experiment, it was reversed; NAIP concentration was much higher than that of organic phosphorus, possibly indicating the transformation of organic phosphorus to NAIP during the experimental period. Both concentrations of $NH_4^+-N$ and $PO_4^{3-}-P$ in the overlying and percolated water were lower in the planted pots than in the non-planted. The concentration of $NO_3^--N$ in the percolated water, however, was higher in the planted pots than in the non-planted. The data was discussed with regard to the potential effects of a submerged plant on dynamics of phosphorus and nitrogen in the rhizosphere of the sediment.

• Asian-Australasian Journal of Animal Sciences
• /
• v.13 no.7
• /
• pp.922-928
• /
• 2000

The effects of animal species and supplements on rumen fluid characteristics, plasma urea-N (PUN) concentration, plasma urea-N pool size, urea-N degradation in the gut and urea-N net flux (urea-N synthesis rate) were studied in goats and sheep, with some minor differences detected. The animals were fed either chopped rice straw ad libitum+200 g soybean meal (SBM), or chopped rice straw ad libitum+190 g soybean meal+300 g sago meal (SBM+SM) for 14 days. The supplements were isonitrogenous (80 g crude protein/animal/d). [$^{14}C$]-urea was used as the marker for urea metabolism studies. Two animals from each species were fed either supplement in a cross-over design in two periods. The results showed that rumen pH was significantly (p<0.001) lower in animals fed SBM+SM than those fed SBM supplement. The ammonia concentrations of rumen fluid were significantly (p<0.01) higher in sheep (382.9 mg N/L) than goats (363.1 mg N/L) when fed SBM supplement but lower (282.5 mg N/L) than that of goats (311.0 mg N/L) when fed SBM+SM supplement. Total VFA concentrations were significantly (p<0.05) higher in animals fed SBM+SM supplement than those fed SBM supplement. Goats had significantly (p<0.01) higher molar proportions of acetate (79.1, 77.7%, respectively) than sheep (75.8, 74.0%, respectively) in both supplements. The molar proportion of acetate was significantly (p<0.05) higher, while that of butyrate lower in animals fed SBM supplement than those fed SBM+SM supplement. In animals fed SBM supplement, the molar proportion of propionate was significantly (p<0.01) higher in sheep (18.0%) than in goats (15.6%), but in animals fed SBM+SM, the molar proportion of butyrate was significantly (p<0.01) higher (9.6%) in sheep than in goats (7.2%). Plasma urea-N concentration, plasma urea-N pool size, urea-N degradation in the gut, urea-N net flux and the fraction of urea-C from the blood entering the rumen were not significantly different between goats and sheep fed either supplement. However, PUN concentration was significantly (p<0.05) lower in animals fed SBM+SM supplement (average of 13.8 mg N/100 ml) than in those fed SBM supplement (average of 16.5 mg N/100 ml). The urea net flux was significantly (p<0.05) higher in goats (average of 14.5 g N/d) than sheep (average of 12.9 g N/d), and animals fed SBM supplement showed higher (average of 14.9 g N/d) urea net flux than animals fed SBM+SM supplement (average of 12.9 g N/d). A significant (p<0.05) positive correlation was observed between urea-N net flux and urea-N degradation; urea-N net flux and pool size; urea-N net flux and urea excretion in the urine; and PUN and rumen ammonia in goats. While in sheep, significant (p<0.05) positive correlation was observed between urea-N net flux and urea excretion in the urine; and PUN and rumen ammonia.