• 반도체디스플레이기술학회지
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• 제8권1호
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• pp.1-5
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• 2009

Typically, single-wafer wet etching is done by dispensing chemical onto the front and back side of spin wafer. The wafer is fixed by a number of chuck pins, which obstruct the chemical flow and would result in the incomplete removal of the remaining film, which can become a source of contamination in the next process. In this paper, we introduce a novel design of wafer chuck, in which chuck pins are groupped into two and each group of pins fixes the substrate alternatively. Two groups of chuck pins fix the high-speed spin substrate with non contact method using a magnetic material. The actual process has been executed to observe the effectiveness of this new wafer chuck. It was found that the new wafer chuck performed better than the conventional wafer chuck for removing the remaining film from the bevel and edge side of substrate.

• 한국지하수토양환경학회지:지하수토양환경
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• 제18권6호
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• pp.18-31
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• 2013

This study was performed to examine use of the pump-and-treat method for remediation of TCE, CF and CT in groundwater contaminated by DNAPL. The Woosan industrial complex is located in Wonju, about 120 km east of Seoul, Korea. Two pumping wells (KDPW7 and KDPW8) and five monitoring wells (KDMW7, KDMW8, KDMW9, KDMW10, and SKW2) were installed for the test. An asphalt laboratory is a main source of the extensive subsurface contamination at this site. To evaluate change in the concentrations of TCE, CF, and CT in groundwater in the study area, three rounds of pump-and-treat pilot tests were performed (6 July to 6 August, 22 August to 6 September, and 19 September to 2 December in 2011). The groundwater levels and the concentrations of TCE, CF, and CT exhibited negative correlations in the wet season but positive correlations in the dry season, which suggests that the TCE concentrations were mainly controlled by dilution through rainfall during the wet season and by residual TCE, CF, and CT in the unsaturated zone during the dry season. These possibilities should be considered in the full-scale remediation plan.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 추계학술대회 논문집
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• pp.484-487
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• 2005

In order to get the surface characteristics of the HDI of HDD, the surface damage mechanisms must be totally understood. Particle contamination in hard disk drives is a big concern in today's magnetic recording industry since they are major sources of reliability problems. Namely upon contact with the slider or a contaminant particle, the disk may be scratched or the particles may be embedded into the disk surface. In this work, comparison of scratches was made between those found on actual hard disks and those created using a scratch tester. It was found that ramp loading method is an effective way to make similar scratches as the actual ones. From the ramp loading condition, the relationship between the pressure and the scratch track width could be identified.

• Nuclear Engineering and Technology
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• 제54권8호
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• pp.3043-3050
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• 2022

In Korea, all nuclear power plants (NPPs) participate in annual performance tests including in vivo measurements using the FastScan, a stand type whole body counter (WBC), manufactured by Canberra. In 2018, all Korean NPPs satisfied the testing criterion, the root mean square error (RMSE) ≤ 0.25, for the whole body configuration, but three NPPs which participated in an additional lung configuration test in the fission and activation product category did not meet the criterion. Due to the low resolution of the FastScan NaI(Tl) detectors, the conventional peak analysis (PA) method of the FastScan did not show sufficient performance to meet the criterion in the presence of interfering radioisotopes (RIs), ¹³⁴Cs and ¹³⁷Cs. In this study, we developed an artificial neural network (ANN) to improve the performance of the FastScan in the lung configuration. All of the RMSE values derived by the ANN satisfied the criterion, even though the photopeaks of ¹³⁴Cs and ¹³⁷Cs interfered with those of the analytes or the analyte photopeaks were located in a low-energy region below 300 keV. Since the ANN performed better than the PA method, it would be expected to be a promising approach to improve the accuracy and precision of in vivo FastScan measurement for the lung configuration.

• 한국지구과학회지
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• 제44권4호
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• pp.291-306
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• 2023

Shallow groundwater in rural areas is primarily polluted by agricultural activities. Nitrate-nitrogen is an indicator of artificial pollution. In this study, the hydrochemical characteristics and nitrate-nitrogen pollution of shallow groundwater were examined in two agricultural villages (Hyogyo-ri and Sinan-ri) in Chungcheongnam-do Province, Korea. Physicochemical quality analysis of shallow groundwater and stream water in the field, and chemical analysis in the laboratory were conducted from July 2020 to October 2021. In Hygyo-ri and Sinan-ri villages, shallow groundwater mainly belonged to the Ca-Cl, Ca-H CO₃, Na-HCO₃, and Na-Cl types, whereas stream water predominantly belonged to the Ca-HCO₃ type. The nitrate-nitrogen concentration in shallow groundwater varied depending on the season, displaying an increased concentration of nitrate-nitrogen in the dry season compared to the rainy season. Stream water may be influenced by runoff into villages from the surrounding area, although both shallow groundwater and stream water are affected by artificial pollution. In addition, the nitrate-nitrogen concentration in stream water was lower than that in shallow groundwater.

• Toxicological Research
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• 제34권3호
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• pp.211-220
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• 2018

Early life exposure to aflatoxin B1 (AFB1) and low protein diet through complementary foods during weaning is common in parts of Africa and Asia. This study evaluated the effect of co-exposure to AFB1 and low protein diet on the extrahepatic tissues of rats. Twenty-four three-week old weanling male albino rats were used for this study and were randomly assigned into four groups: group 1 served as control and was fed normal protein diet (20% protein), group 2 was fed low protein diet (5% protein), group 3 was fed normal protein diet + 40 ppb AFB1 while group 4 received low protein diet + 40 ppb AFB1, all for eight weeks. Afterward, biomarkers of anemia (packed cell volume (PCV), hemoglobin) and kidney function (urea, uric acid, and creatinine) were determined in the blood while biomarkers of oxidative stress were determined in the tissues spectrophotometrically. Co-exposure to AFB1 and low protein diet significantly (p < 0.05) decreased body weight gain and PCV, increased biomarkers of kidney functions and induced oxidative stress in the tissues studied. There was significant (p < 0.05) reduction in glutathione concentration while TBARS was significantly increased in the tissues. Co-exposure to AFB1 and low protein diet had additive effects on decreasing the weight gain and potentiation effect of kidney dysfunction in the rats. The co-exposure also decreased antioxidant enzymes and increased oxidant status in the tissues. Our results demonstrate that this co-exposure has deleterious health effects on extrahepatic tissues and should be a public health concern especially in developing countries where AFB1 contamination is common.

• 청정기술
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• 제24권3호
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• pp.157-165
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• 2018

본 연구에서는 초임계 이산화탄소와 공용매 첨가물을 이용하여 실리콘 웨이퍼 표면의 $Si_3N_4$ 파티클을 제거하는 기술을 조사하였다. 우선, 몇 가지 계면활성제와 첨가제에 관한 초임계 이산화탄소 용해도 및 파티클 분산성 평가를 통하여 초임계 공정에 대한 적합성을 확인하였다. 다양한 변수를 조정하여 파티클 세정 실험을 진행하여 최적의 제거 조건을 확립하였다. 실험에 사용된 계면활성제는 파티클 제거 효과가 떨어졌으며, 실험 후 이차 오염물이 형성됨을 확인하였다. 반면 trimethyl phosphate는 IPA공용매와 미량의 HF와 혼합된 세정 첨가제로서 초임계 이산화탄소에 5 wt%로 포함한 유체로 온도 $50^{\circ}C$, 압력 2000 psi에서 $15mL\;min^{-1}$의 유속으로 4분 간 세정한 결과, 85%의 파티클 제거 효율을 나타내었다.

• 한국환경보건학회지
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• 제9권2호
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• pp.1-10
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• 1983

The purpose of this study was to analyze general ingredient of bean cured on the market and to examine its exposure to bacterial contamination. For this study, 17 samples (each 9 samples for general bean curd, soft bean curd, and uncurdled bean curd) were randomly collected from nine areas in Seoul from the beginning of April, 1983 to the beginning of June, 1983. The result of ingredient analysis of moisture, ash, and protein of bean curd was compared with the standard set by the Ministry of Health & Social Affairs. In order to find out exposure of bean curd on the market to bacterial contamination, total biological bacteria and coliform group were examined. Experimental results were shown as follows 1) Results of ingredient analysis of moisture, ash, and protein of general bean curd showed that total samples in both moisture and protein met the standard set by the Ministry of Health & Social Affairs but 44.4% of the samples in ash was below the above standard, indicating average 82.0%, 0.9% and 9.6% in moisture, ash, and protein order. 2) Experimental results of moisture, ash, and protein of soft bean curd demonstrated 90.2%, 0.5% and 4.3% respectively total samples in both moisture and protein satisfied the self-criteria set by the Soft Food Co-operative Association of Seoul City but 11.1% of the samples in ash didn't meet the self-criteria. 3) Total samples of uncurdled bean curd satisfied the self-criteria set by the above association, indicating average 92.0%, 0.4%, and 3.5% in moisture, ash, and protein order. 4) Total biological bacteria and coliform group detected in general bean curd showed that more than 10$^5$/g in total biological bacteria accounted for 88.8% of the samples and that 10$^4$/g or more in coliform group accounted for 77.7% of the samples. The result proves that general bean curd has been exposured to a severe bacterial contamination. 5) Result of total biological bacteria and coliform group detected in such packed bean curd as uncurdled bean curd and soft bean curd showed that 61.6% of the samples exceeded 10$^6$/g in total biological bacteria and 27.7% of the samples exceeded 10$^3$/g in coliform group. 6) According to the change with time and temperatures in total biological bacteria and coliform group of general bean curd, general bean curd began to decay around 72 hours at 4$\circ$C and around 48 hours at 23$\circ$C and around 24 hours at 37$\circ$C and, at that time, total biological bacteria approached 10$^6$/g while coliform group did 10$^6$/g. The result indicates that temperature has a great effect on bacteria counts and decay.

• 한국가금학회지
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• 제33권4호
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• pp.295-301
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• 2006

본 실험은 육계에서의 Marek's disease(MD) 백신에 대한 안전성과 효용성을 국내에 기 도입된 18일령 계란에서의 백신 접종 방법(In-Ovo vaccination)을 이용하여 평가하고자 실시하였다. 육계에서의 MD 오염율은 nested PCR을 이용하였으며 백신 접종군과 비접종군간의 생산성 차이를 출하 일령, 평균출하체중, 출하율, 사료 효율을 기본으로 하는 생산 지수를 측정하여 비교하였다. 백신에 의한 면역 억제 현상을 파악하기 위하여 접종 농장에서 채취한 혈청에서의 항체 역가수준과 F낭의 무게 변화를 검사하였다. 국내 육계에서의 MD 발생율을 파악하기 위하여 nested PCR을 실시한 결과 조사 대상 농장 중 26.09%가 오염되었으며, 백신 접종 농장과 비접종 농장간의 생산 지수의 차이는 통계학적으로 유의한 차이가 없었다. 그러나 MDV 오염군에서의 MD 백신 접종 농장의 생산 지수가 비접종 농장보다 높아 간접적으로 효과가 있음이 인정되었다. 면역 억제여부를 파악하기 위한 검사에서는 두 그룹 간 B/B ratio 차이는 없었으나 두 계군 모두 출하 시 심한 위축을 보여주어 혈청 검사 성적과 연계하여 볼 때 국내 육계 농장에서의 IBD 감염이 만연되어 있다는 것을 알 수 있었다. 본 연구를 통해서 국내 육계에서의 MDV 오염율이 파악되었으며, In-Ovo 백신 접종에 의한 MD 백신 접종은 안전성에 있어서는 별다른 문제가 없었으나 효능면에 있어서는 MD 야외감염율이 낮고 IBD와 같은 면역 억제 질병의 감염이 만연되어 있어 정확한 평가가 되지 않아 앞으로 후속 연구가 진행되어야 할 것으로 판단되었다.

• 대한치과교정학회지
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• 제26권3호
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• pp.309-316
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• 1996

본 연구는 산부식 법랑질의 타액오염 효과를 오염 시간별 전단결합강도를 통해 알아보고 주사 전자현미경으로 표면 변화를 관찰하고자 하였다. 타액오염 시간이 전단결합강도에 미치는 영향을 관찰하기 위하여 38% 인산용액으로 15초와 60초 산부식한 후 타액으로 0초, 1초, 20초, 60초동안 오염시켜 세척과 건조 후 주사 전자현미경으로 부식면을 검경하였으며, 교정용 레진을 이용하여 브라켓 접착 후 전단결합강도를 측정하고 통계 처리하여 다음과 같은 결과를 얻었다. 1. 타액에 오염시키지 않은 15초 산부식 군과 60초 산부식 군 사이의 전단결합강도는 통계적으로 유의한 차를 보이지 않았으나, 60초 산부식군에서 전단결합강도가 조금 낮았다. 2. 15초, 60초 산부식군에서 대조군, 1초, 20초, 60초의 타액오염 시간의 차이 에 따른 전단결합강도는 통계적으로 유의한 차를 보이지 않았으나, 타액오염시간의 증가에 따라 전단결합력이 낮아지는 경향을 보였다. 3. 주사 전자현미경 관찰시 대조군에서는 특징적인 부식양상을 보였으나 타액오염 군에서는 유기물이 침착되어 있었다.