• 분석과학
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• 제23권3호
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• pp.284-294
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• 2010

하천수 시료를 이용한 중금속분석용 수질표준물질, NIER-I08RW 및 NIER-I09를 제조하여 납, 카드뮴, 크롬, 구리 등 중금속 4 종에 대한 인증분석 및 불확도 등을 평가하였다. 균질성 평가 결과, 병간균질도가 숙련도시험의 목표표준편차의 0.3 배 이하로서 숙련도시험용 시료로서 사용하기에 충분히 균질한 시료인 것으로 확인되었다. 제조된 표준물질을 이용하여 국내 환경측정분석기관을 대상으로 숙련도시험을 실시하고, 설정값의 설정방법에 따른 로버스트 Z 값의 변동을 비교하였다. 다른 항목에 비해 농도가 낮은 NIER-I08RW의 카드뮴 항목을 제외하고는, 특성값과 참가기관의 합의값의 차이인 상대편차, $B_{relative}$는 모두 ${\pm}$1 이하로서 크지 않았으며, 설정값을 달리 설정함으로 Z 값이 달라진 경우는 46 개로서 전체의 2.9%에 불과하였다.

• 분석과학
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• 제33권6호
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• pp.245-251
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• 2020

납은 암석의 연대측정, 지각의 진화 및 오염원의 기원 추적과 같은 지구화학적 연구에 유용하게 사용되어지는 원소로, 이를 위해선 고순도 원소 분리가 선행되어져야한다. 본 연구에서는 납을 분리해 내는데 있어서 용리액의 농도가 6M HCl 과 8M HCl 중 어느 것이 더 효율적인지 비교 검토 하였다. 그 결과, 6M HCl의 경우 8M HCl 보다 용리액을 다량으로 사용했음에도 불구하고 납 분리에 있어서는 효율적이지 않았다. 그리고 납 분리법에 대한 신뢰성 검증을 위하여 납 동위원소 표준물질(NIST NBS981)과 암석표준시료(BCR-2, GSP-2, JG-1a)의 납 동위원소비를 열이온화질량분석기로 측정한 결과, 기존 보고 값과 오차 범위 내에서 잘 일치하였다.

• 분석과학
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• 제19권2호
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• pp.172-180
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• 2006

본 연구는 유해폐기물에 의한 환경오염을 예방하기 위해 폐기물 시험방법과 신규 항목을 설정하기 위해 수행하였다. 국내외 유해폐기물의 규제기준, 시험항목 등을 조사검토하여 유해물질에 대한 우선순위를 선정하였다. 선정한 Ba, Be, Cr(VI), F, Ni, Sb, Se, V 8종의 유해물질을 함유한 오니, 폐유, 소각재 등 폐기물 인증표준물질을 사용하여 전처리방법을 비교분석하였다. 이 결과를 통해 시험방법(안)을 확립하고, 관련 항목 배출 가능성이 있는 표본사업장을 선정하여 시료 37건을 채취분석하였다.

• 분석과학
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• 제24권6호
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• pp.503-509
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• 2011

비표면적은 기능성 나노소재의 특성평가에 있어 매우 중요한 지표가 되고 있다. 하지만 비표면적 측정은 측정방법 및 해석 방법에 따라 결과에 많은 차이가 있어왔다. 국내에 보급된 비표면적 측정장치의 신뢰성 검증을 위하여, 21개 산학연 기관을 대상으로 순회평가(RRT)를 수행하였다. 순회평가 분석 결과 많은 기관에서는 비표면적 측정장비의 흡착량 측정 성능에 문제가 있음을 확인 하였으며, 이는 인증기준물질의 필요성을 확인시켜 주었다. 또한 BET 분석방법이 분석자의 주관에 의해 많이 좌우됨을 확인 하였다. 즉 BET 분석구간의 선택영역에 따라 CRM I의 경우 16% 까지 차이를 줄 수 있음을 확인하였는데, 이는 적정한 BET 구간의 선택을 위한 BET 매개변수 C 값과 fitting 상관계수 R 값에 대한 기준이 필요함을 확인시켜 주었다. 이러한 순회평가의 경험과 검증된 비표면적 인증물질 및 표준 절차서의 보급은 산업계에 신뢰성 있는 비표면적 측정결과를 주게 됨으로서, 일관성 있는 공정운용에 의한 품질관리, 생산성 향상, 안정성 판단 및 신제품 개발 등에 기여할 것이다.

• 한국환경과학회지
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• 제20권9호
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• pp.1087-1093
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• 2011

The mixotrophic marine ciliate Mesodinium rubrum possesses a highly modified algal endosymbiont as a nutrition source for the species. Accordingly, we assumed that the species can reflect the ecotoxicity on marine producer (as phytoplankton) and consumer (as zooplankton) both. A series of experiments were conducted to identify the potential of the species as a standard test species for marine ecotoxicological study. The comparison of species sensitivity on reference toxic materials was made using potassium dichromate for phytoplankton and copper chloride for zooplankton. The ciliate revealed the highest sensitivity on both reference materials among the seven test species including phytoplankton, benthic copepod and rotifer species. The toxicity end point of the species was 72hr-$EC_{50}$=1.52 mg/L (as potassium dichromate) estimated by population growth inhibition (PGI), which is more sensitive than the most sensitive phytoplankton Skeletonema costatum (72hr-$EC_{50}$=3.05 mg/L). As comparison to rotifer, it also revealed higher sensitivity on copper chloride; 72hr-$EC_{50}$=0.38 mg/L for ciliate and 48hr-$EC_{50}$=0.48 mg/L for rotifer. Also, the elutriate toxicity test of various ocean disposal wastes were conducted to identify the potential of ciliate toxicity test application using industrial waste sludges. The toxicity of leather processing waste sludge was highest on the ciliate, followed by dyeing waste sludge and dye production waste sludge as an increasing order of toxicity. 72h-$EC_{50}$ of ciliate PGI test was 1.83% and that of S. costatum 3.84% for leather waste sludge which showed highest toxicity. The toxicity test results also revealed that the highest sensitivity was observed on ciliate species on ocean disposed sludge wastes. Also, ciliate toxicity test well discriminated the degree of toxicity between sludge sources; 72h-$EC_{50}$ values were 1.83% for leather processing waste sludge, 16.75% for dye production waste sludge and 27.75% for textile production waste sludge. Even the laboratory culture methods of the species were not generally established yet, the species has high potential as the standard test species for marine toxicity test in terms of the dual reflection of phyto- and zooplankton toxicity from single test, sensitivity and test replicability.

• Toxicological Research
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• 제33권3호
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• pp.225-231
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• 2017

National reference standards (NRSs) for biologics are established through potency estimation by a multi-center joint study of standard materials used in the approval process for national lot release and quality control of vaccines, blood products, and other biologics. In this study, a stability evaluation was conducted to determine whether the potency of NRSs for six blood products was being maintained at a consistent level in Korea. The present study conducted real-time stability tests via in-vivo/in-vitro bioassay on NRSs for blood coagulation factor VIII concentrate (2nd standard), antithrombin concentrate, prekallikrein activator, anti-hepatitis B immunoglobulin, blood coagulation factor IX concentrate, and anti-tetanus human immunoglobulin, as well as a trend analysis using cumulative annual results. The real-time stability test results showed that the mean potency of six NRSs was all within the control limit. In the trend analysis, the potency of NRS for blood coagulation factor VIII concentrate (2nd standard) showed a decreasing trend, while the potency of all other products had been stably maintained. The present study confirmed that the mean potency of NRSs for six blood products had been stably maintained in Korea. The findings of the present study establish a foundation that can ensure the quality of NRSs for biologics in Korea, and it is expected to make a major contribution to the supply of high-quality biologics.

• Korean Journal of Radiology
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• 제22권12호
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• pp.1964-1973
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• 2021

Objective: To investigate the diagnostic performance of CT fractional flow reserve (CT-FFR) for myocardial bridging-related ischemia using dynamic CT myocardial perfusion imaging (CT-MPI) as a reference standard. Materials and Methods: Dynamic CT-MPI and coronary CT angiography (CCTA) data obtained from 498 symptomatic patients were retrospectively reviewed. Seventy-five patients (mean age ± standard deviation, 62.7 ± 13.2 years; 48 males) who showed myocardial bridging in the left anterior descending artery without concomitant obstructive stenosis on the imaging were included. The change in CT-FFR across myocardial bridging (ΔCT-FFR, defined as the difference in CT-FFR values between the proximal and distal ends of the myocardial bridging) in different cardiac phases, as well as other anatomical parameters, were measured to evaluate their performance for diagnosing myocardial bridging-related myocardial ischemia using dynamic CT-MPI as the reference standard (myocardial blood flow < 100 mL/100 mL/min or myocardial blood flow ratio ≤ 0.8). Results: ΔCT-FFR_systolic (ΔCT-FFR calculated in the best systolic phase) was higher in patients with vs. without myocardial bridging-related myocardial ischemia (median [interquartile range], 0.12 [0.08-0.17] vs. 0.04 [0.01-0.07], p < 0.001), while CT-FFR_systolic (CT-FFR distal to the myocardial bridging calculated in the best systolic phase) was lower (0.85 [0.81-0.89] vs. 0.91 [0.88-0.96], p = 0.043). In contrast, ΔCT-FFR_diastolic (ΔCT-FFR calculated in the best diastolic phase) and CT-FFR_diastolic (CT-FFR distal to the myocardial bridging calculated in the best diastolic phase) did not differ significantly. Receiver operating characteristic curve analysis showed that ΔCT-FFR_systolic had largest area under the curve (0.822; 95% confidence interval, 0.717-0.901) for identifying myocardial bridging-related ischemia. ΔCT-FFR_systolic had the highest sensitivity (91.7%) and negative predictive value (NPV) (97.8%). ΔCT-FFR_diastolic had the highest specificity (85.7%) for diagnosing myocardial bridging-related ischemia. The positive predictive values of all CT-related parameters were low. Conclusion: ΔCT-FFR_systolic reliably excluded myocardial bridging-related ischemia with high sensitivity and NPV. Myocardial bridging showing positive CT-FFR results requires further evaluation.

• 한국대기환경학회지
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• 제5권2호
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• pp.21-29
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• 1989

The metals present in atmospheric particulate come from various sources; natural or anthropogenic. Among various metals Fe, Zn, Pb, Cu, and Mn are of particular concern in as much as they are not only present in large quantity, but toxic to human body. A simple, fast, and non-destructive analytical method for these metals in atmospheric particulate was developed and the analytical details were described herein. The method involves the measurements of X-ray fluorescence of sample contained in filters and comparing it with those for standards. The standard filters were prepared by applicating premeasured standard solution to the filters and then drying. The accuracy of the method was tested by analyzing standard reference materials and by independently analyzing samples using a different, previously accuracy-proven method, inductively coupled plasma atomic emission spectrometry, and comparing the results obtained. Analytical sensitivities and detection limits of the present method were 62.9, 178.2, 82.9, 146.1, 37.2, 120.3 cps/$\mug/cm^2$ and 39.0 35.6, 137.5, 125.9, 182.6, 72.8 $ng/cm^2$ for Fe, Zn, Pb, Cu, Mn, and Ni respectively. The method was applied to Seoul atmospheric particulate and some results were reported.

• 치과방사선
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• 제23권1호
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• pp.125-136
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• 1993

The geometrically standardized intraoral radiographs using 5 occlusal registration materials were taken serially from immediate, 1 day, 2, 4, 8, 12, and 16 weeks after making the bite blocks. And the resultant images were digitally subtracted using the immediately taken film as reference images. The qualities of those subtracted images were evaluated to check the degree of reproducibility of each impression material. The results were as follows: 1. The standard deviations of the grey scales of the overall subtracted images were 4.9 for Exal1ex, 7.2 for Pattern resin, 9.0 for Tooth Shade Acrylic, 12.2 for XCP only, 14.8 for Impregum. the lesser the standard deviation, the better the quality of the subtracted images. 2. The standard deviation of the grey scales of the overall subtracted images were grossly related to those of the localized horizontal line of interest. 3. Exaflex which showed the best subtracted image quality had 15 cases of straight, 14 cases of wave, 1 case of canyon shape. Impregum which showed the worst subtracted image quality had 4 cases of straight, 8 cases of wave, 18 cases of canyon shape respectively.

• 대한치과보철학회지
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• 제27권2호
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• pp.249-259
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• 1989

Dental impression materials often become contaminated with patients' saliva and blood which creates the potential for cross-infection. It was the purpose of this study to investigate the effects of disinfection of three different rubber impression materials with four different disinfecting solutions. Polysulfide, vinyl polysiloxane and polyether impression materials were mixed according to the manufacturer's directions and samples were formed on a stainless steel model. On removal from the standard model, impressions were immersed in a disinfectant (acid-potentiated glutaraldehyde, phenollic compound, chlorine compound, iodophor) at room tempera tures for ten minutes. After disinfection, the distance between reference points(linear dimension) was measured using the non-contact automatic cordinate measuring projector(MZ-1, Nikon). Through statistical analyses on the data from this study,. the following conclusions were obtained. 1. Polysulfide, vinyl polysiloxane impressions were disinfected without dimensional change.(p>0.05) 2. Polyether impressions which were immersed in acid-potentiated glutaraldehyde were statistically different from control group.(p<0.05) But the amount of shrinkage(0.04%) would not be clinically significant. 3. By immersion of polysulfide, vinyl polysiloxane, polyether impressions in Banicide, Biocide, Multicide plus, sodium hypochlorite for ten minutes, clinically accurate impressions were obtained without dimensional change.