• Journal of Korean Society of Environmental Engineers
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• v.34 no.1
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• pp.7-15
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• 2012

The levels of indicator PCBs were determined in 132 human milk samples (Colostrum, 30th days after delivery, 60th days after delivery) collected in 2006 according to World Health Organization's (WHO) protocol. In addition, concentrations of indicator polychlorinated biphenyls (PCBs) were measured by the isotope dilution method with high resolution gas chromatograph/high resolution mass detector (HRGC/HRMS), which gave accurate and precise data for estimations of international trend and comparisons. Average daily intakes (ADIs) of all analytes were calculated. The median level of total indicator PCBs was 14 ng/g lipid, which is significantly lower than the level found in individuals from other countries. PCB congeners 138, 153 and 180 accounted for about 65% of the sum of the indicator congeners analyzed. The concentration of the most abundant PCB 153 is positively correlated with the concentration of the sum indicator PCBs (p<0.001). In this study, concentrations of total indicator PCBs significantly decreased with increasing number of children for a mother, indicating that parity and breast-feeding period an important role in the accumulation and elimination of these compounds in lactating women. The ADI for the median of total indicator PCBs for an infant was evaluated at $0.077{\mu}g/kg{\cdot}bw/day$ from birth to 6 months of age. The present study shows that concentrations of PCB 118 primipara breast milk have decreased 25~35 since 1998, and that this trend is continuing.

• Ocean and Polar Research
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• v.29 no.4
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• pp.297-302
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• 2007

Atmospheric levels of polychlorinated biphenyls (PCBs) at the King Sejong station were monitored for one year using passive air samplers. Low-chlorinated PCB homologues were predominant in all samples. PCB levels were observed to decrease with distance from the station, which may indicate that a significant part of PCBs could be of local origin. Although the level of PCBs at the King Sejong station is very low (${\Sigma}_9PCB$ (18, 52, 101, 118, 128, 138, 153, 180, 187): $2.3\;pg\;m^{-3}$) probably due to decrease in the global PCB emissions, it is one order of magnitude higher than a background level in the Antarctic. Based on this preliminary study, more interpretation on PCB data and meteorological conditions is required.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2006.02a
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• pp.119-138
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• 2006

1. 모바일 제품 고기능/소형화를 위해 3차원 실장 [3차원 부품 Stack, Embedded PCB] 필요성 증대 2. 고밀도 실장을 위해 기존 부품업체 [능동, 수동, 기타부품], PCB 업체, Set 업체간의 명확한 기술구분이 사라짐 $\rightarrow$ 기존 부품의 조합에 의한 조립이라는 패러다임 변화 요구된 [의식 개혁 필요] 3. 신 실장기술 도입의 가장 큰 장애물 중 하나는 신뢰성 확보임 신규 기술 연구/개발과 동시에 충분한 신뢰성 확보가 필수

• Journal of Environmental Health Sciences
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• v.39 no.2
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• pp.151-158
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• 2013

Objective: This study was carried out to determine the depositional characteristics of pine needles, pine tree bark, moss, and soil, which are used as a passive air sampler (PAS) of atmospheric polychlorinated biphenyls (PCBs). Methods: All four media were sampled from the same site. PCB concentrations were analyzed by GC/MSD, and the lipid contents were measured using the gravimetric method. Results: The total PCB concentration (IUPAC No. 28, 52, 101, 138, 153, 180) was the highest in soil (227.97 pg/g dry), followed by pine needles (71.36 pg/g dry), pine tree bark (44.58 pg/g dry), then moss (21.91 pg/g dry). Pine needles contained the highest lipid contents (21.31 mg/g dry), whereas soil (10.01 mg/g dry), pine tree bark (4.85 mg/g dry), and moss (1.92 mg/g dry) contained less. The concentration of lower-chlorinated PCBs was relatively high in pine needles, pine tree bark and moss, but not in soil. The PCB concentrations were proportional to their lipid contents in pine needles, pine tree bark and moss, but a different trend was revealed in soil. Conclusions: The PCBs concentrations in the media were affected by various factors including atmospheric PCB concentrations, lipid contents, and depositional pathways. However, each of these factors had a varying influence depending on the type of medium.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.06a
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• pp.135-138
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• 1998

This paper presents the results of measured permittivity of PCB sheet material in the frequency range of 0.1[GHz] - 2[GHz] and temperature range of $25[^{\circ}C]$ - $85[^{\circ}C]$. Microstrip lines with different physical length are implemented to measure the attenuation and phase shift of the signals though these lines. The loss factor of these materials could be obtained with the dielectric constant and the attenuation of the microstrip lines.

• Journal of Korean Society of Water and Wastewater
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• v.26 no.6
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• pp.757-766
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• 2012

In this study, we have examined concentration distribution and patterns of PCBs in waters, sediments and soils in an agricultural area of South Korea to investigate the relationship between PCBs sources and concentration levels. The concentration of PCBs in water samples were ranged from lower values below detection limit to 8.25 ug/L and the concentration of PCBs in sediment samples were ranged from lower values below detection limit to 76.67 ug/Kg. The concentration of PCBs in soil samples were ranged from lower values below detection limit to 23.51 ug/Kg. These contamination levels were far below the guideline values suggested for environmental quality assessment. The homologue patterns in samples varied from sample to sample, but isomer patterns were very similar with each other. PCB-138 and PCB-153 were predominant congeners in the soil and sediment, which were similar to the results obtained from previous studies. With these results, the assessment of potential sources of PCBs contamination in the sediments of the Nakdong river basin was performed. The principal components were extracted by Principal Component Analysis(PCA). As the result of PCA, it could be expected that PCBs in samples of this study were more affected by PCB products than combustion processes and mostly affected by already-known sources. The PCBs in the soil and sediment samples were related with commercial PCB products.

• Analytical Science and Technology
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• v.12 no.2
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• pp.151-158
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• 1999

This study was conducted to measure the residual PCBs in sediments of 4 great rivers in Korea by gas chromatography-mass spectrometry. From the results, PCBs were positively detected in all samples. The residue levels of total PCBs in sediments in near of SS and OS were $290.87{\mu}g/kg$ and $221.11{\mu}g/kg$, respectively. The PCBs contamination may be in association with total organic compound (TOC) in sediments. Congener 66, 74, 90, 101, 105, 110, 118, 138, 149, 153, 180, 187 as IUPAC No were predominant species found in sediments and the polyCBs detected most aboundantly in sediments were tetraCBs and pentaCBs. From the study, it appears that the PCBs contamination in sediments of 4 great rivers is not serious and the analysis from enough many sites is needed for the next survey.

• YAKHAK HOEJI
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• v.46 no.4
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• pp.247-257
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• 2002

Persistent organochlorine pesticides and polychlorinated biphenyls (PCBs) have been used intensively in agriculture or industry for a long time. The occurrence of organochlorine pesticides and PCBs in the environment and subsequently in parts of the food chain, resulting in the intake of these compounds by man and animal. The measure of the levels of organochlorine pesticides and PCBs in tissues or blood of human populations are good markers in determining the extent of exposure and in the evaluating the hazards. So, most countriess have conducted initial monitoring programs to determine organochlorine pesticides and PCBs in human tissues. But a few report has been presented in Korea. In this study, $\alpha$-BHC, $\beta$-BHC, ${\gamma}$-BHC, $\delta$-BHC, p,p'-DDT, p,p'-DDD, p,p'-DDE, endrin, dieldein, aldrin and 7 marker PCBs (28, 52, 101, 118, 138, 153, 180) were determined in human blood, adipose tissue and liver tissues collected at autopsy of 10 men and 10 women, 13-79 year of age. Significant differences in the levels of organochlorine pesticides and PCBs between districts where they had lived were found in the following chemicals: total PCB in the blood : $\beta$-BHC, total BHC, p,p'-DDE and total DDT in the adipose tissue : p,p'-DDE, total DDT and PCB 118 in the liver. No significant difference was found in the levels of organochlorine pesticides and PCBs between sexes and ages. Though the levels of organochlorine pesticides and PCBs were relatively lower than that of other countries, we could know that organochlorine pesticides and PCBs have been widely distributed in Korean human body.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.3
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• pp.130-138
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• 2010

The thermal reliability of the closed-type BLDC motor for the high speed axial fans is analyzed by a numerical method in this paper. Since the module and the motor part are combined in a closed case, the heat generated from a rotor in the motor and the electronic components in the PCB module can not be effectively removed to the outside. Therefore the module will easily fail by high temperature. The accelerated-life testing was accomplished to formulate the life equation and numerical method is used to predict the inside temperature of the PCB module, which is one of the life equation parameter according to the environment. When the environment temperature of BLDC motor is 21, 35 and 50 $^{\circ}C$, the temperature in the PCB space is predicted as 73.4, 87.5 and 102.4 $^{\circ}C$. Then the life time with the temperature are calculated as 2,239, 863 and 328 hours.

• Journal of the korean society of oceanography
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• v.36 no.4
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• pp.93-100
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• 2001

The concentrations of 20 congeners of PCBs were determined in surficial and dated sediments from Jinhae, Busan, Ulsan and Yeongil Bay of Korea to assess current distributions as well as historical trends. The concentration ranges of total CBs in sediments were nd-138.60 ng/g dry wt. The concentrations of total CBs were significantly different among bays in the southeastern coastal areas (Kruskal-Wallis Test, p=0.036), Showing the Order Of Busan>Ulsan>Yeongil>Jinhae Bay. Predominant PCB homologues were penta-, hexa- and hepta-CBs. The down-core distributions of PCBs showed that the highest concentrations occurred in the late 1960s, coinciding with the onset of industrialization of Korea. The compositions of PCB congeners in sediment among bays were uniform, suggesting that major sources were not changed over time.