• 한국광학회지
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• 제9권6호
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• pp.362-367
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• 1998

중심거리측정법은 서로 붙어있는 두 입자 중심점간의 거리를 측정하여 입자의 지름을 구하는 방법이다. 표면장력에 의해 배열이 형성된 시편 입자들의 초점군을 투과식 광학현미경에 평행 레이저광을 입사시켜 얻어내고 CCD 카메라로 영상을 받아 전산 분석하였다. Global lab image라는 영상처리 프로그램으로 초점들의 중심점을 찾고 붙어있는 입자들의 중심점간 거리를 화소(CCD 카메라의 pixel)단위로 계산하였으며, 화소의 좌표는 레이저 간섭계로 변위를 읽는 이송대를 이용하여 교정하였다. 기존의 측정방법을 개선하여 빠른 시간에 간편하게 측정하면서도 표준입자의 배율고정에 충분한 불확도를 얻을 수 있었다. 본 실험에는 NIST 인증물질인 3$\mu\textrm{m}$와 10$\mu\textrm{m}$ 폴리스티렌구(NIST SRM 1962, 1960)를 측정하였으며, 1%이하의 불확도(신뢰도 99% 수준)로써 NIST 결과와비교하였다.

• 통합자연과학논문집
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• 제16권3호
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• pp.81-95
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• 2023

Colorectal cancer is one of the most common types of cancer worldwide, ranking third after lung and breast cancer in terms of global prevalence. With an expected 1.93 million new cases and 935,000 deaths in 2020, it is more prevalent in males than in women. Evidence has shown that during the later stages of colon cancer, STAT1 promotes tumor progression by promoting cell survival and resistance to chemotherapy. Recent studies have shown that inhibiting STAT1 pathway leads to a reduction in tumor cell proliferation and growth, and can also promote apoptosis in colon cancer cells. One of the recent approaches in the field of drug discovery is drug repurposing. In drug repurposing approach we have virtually screened FDA database against STAT1 protein and their interactions have been studied through Molecular docking. Cross docking was performed with the top 10 compounds to be more specific with STAT1 comparing the affinity with STAT2, STAT3, STAT4, STAT5a, STAT5b and STAT6. The drugs that showed higher affinity were subjected to Conceptual - Density functional theory. Besides, the Molecular dynamic simulation was also carried out for the selected leads. We also validated in-vitro against colon cancer cell lines. The results showed mainly Acetyldigitoxin has shown better binding to the target. From this study, we can predict that the drug Acetyldigitoxin has shown noticeable inhibitory efficiency against STAT1, which in turn can also lead to the reduction of tumor cell growth in colon cancer.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 A
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• pp.173-175
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• 1999

This paper deals with the rotor vibration analysis of Switched Reluctance Motor(SRM) with the 6/4 poles. For this analysis, 3-dimensional mode shapes corresponding to the natural frequency and critical speed map according to rotor speed are presented by using 3D Transfer Matrix Method(TMM). The gyroscopic effect and shear deformation of rotor are considered.

• 통합자연과학논문집
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• 제9권3호
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• pp.177-184
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• 2016

CXC chemokine receptor 2 (CXCR2) is a prominent chemokine receptor on neutrophils and it regulates the neutrophilic inflammation in the lung diseases. CXCR2 antagonist may reduce the neutrophil chemotaxis and alter the inflammatory response. Hence, in the present study, ligand based Comparative Molecular Similar Indices Analysis (CoMSIA) was performed on a series of CXCR2 antagonist named pyrimidine-5-carbonitrile-6-alkyl derivatives. The optimum CoMSIA model was obtained with statistically significant cross-validated coefficients ($q^2$) of 0.582 and conventional coefficients ($r^2$) of 0.987 with steric, electrostatic, hydrophobic, donor and acceptor fields. The contour maps suggest the important structural modifications and this study can be used to guide the development of potent CXCR2 antagonist.

• 한국식품과학회지
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• 제49권2호
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• pp.132-140
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• 2017

시판 누룩을 맥주의 당화과정에 첨가하여 얻은 맥주의 특성을 확인한 결과, 가용성 고형분 함량은 발효 직후에 급격히 줄어들어 숙성기간과 저장기간 동안 비슷한 수치로 이어졌다. pH는 발효 직후 5.7에서 4.1-4.2까지 낮아졌고, 숙성과 저장 기간을 거치면서 비슷한 수치를 유지하였다. 미생물은 대부분 효모균으로 숙성기간인 6일에 약 $5.16{\times}10^5CFU/mL$에서 13일 $2.92{\times}10^6CFU/mL$로 균수는 증가하였다. 맥주의 색은 SRM 색도와 색차계로 분석한 결과 SRM은 누룩의 첨가량이 많아짐에 따라 발효, 숙성, 저장 기간 내내 높은 수치를 보였다. 색차계에서는 누룩의 첨가량이 많아질수록 명도의 L값은 약간 낮아지고 a값은 마이너스 값으로 초록색에 가깝고 황색도의 b값은 높아지는 경향성을 보였다. 맥주의 점도는 누룩의 첨가량이 많을수록 점도가 낮았다. 쓴맛 또한 누룩 첨가량이 많을수록 낮은 값이 나왔다. 아미노산도는 누룩 첨가구에서 더 높은 값이 나타났으나 첨가구내에서의 차이는 없었다. 거품 안정성은 대조구 $135.62{\pm}10.28$으로 N15는 $368.24{\pm}23.25$으로 대조군보다 2배 이상 유의적으로 차이 나는 결과를 보였다. 유리당의 포도당, 설탕, 엿당은 발효, 숙성과 숙성 기간 동안 줄어들었고 유기산은 말산, 시트르산이 효모의 대사산물로 발효, 숙성, 저장 기간에 그 수치가 높아졌다. 누룩을 맥주 당화과정의 효소제 역할로 이용한 실험결과를 통해 맥주 공정 중 당화과정에 누룩을 첨가함으로 새로운 특성의 맥주가 생산될 수 있음을 확인하였다.

• Journal of Biosystems Engineering
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• 제34권5호
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• pp.377-381
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• 2009

Excessive presence of heavy metals in environment may contaminate plants and fruits grown in that area. Rapid on-site monitoring of heavy metals can provide useful information to efficiently characterize heavy metal-contaminated sites and minimize the exposure of the contaminated food crops to humans. This study reports on the evaluation of a bismuth-coated glassy carbon electrode for simultaneous determination of cadmium (Cd) and lead (Pb) in a NIST-SRM 1568a rice flour by anodic stripping voltammetry (ASV). The use of a supporting electrolyte 0.1 M $HNO_3$ at a dilution ratio (sample pretreated with acid digestion in a microwave oven: supporting electrolyte) of 1:1 provided well-defined, sharp and separate peaks for Cd and Pb ions, thereby resulting in strongly linear relationships between Cd and Pb concentrations and peak currents measured with the electrode ($R^2\;=\;0.97$, 0.99 for Cd and Pb, respectively). The validation test results for spiked standard solutions with different concentrations of Cd and Pb gave acceptable predictability for both spiked Cd and Pb ions with mean prediction errors of 6 to 30%. However, the applicability of the electrode to the real rice flour sample was limited by the fact that Cd concentrations spiked in the rice flour sample were overly estimated with relatively high variations even though Pb ion could be quantitatively measured with the electrode.

• Bulletin of the Korean Chemical Society
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• 제32권12호
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• pp.4270-4274
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• 2011

A method is proposed for determining chromium content in the carbon steel pipes of a nuclear power plant (NPP) to evaluate wall thinning caused by flow-accelerated corrosion (FAC). A flat file was used to obtain filings samples. To assess sampling quality, a disk form of SRM 1227 was ground with the flat file, and the amount of Cr in the filings was determined by ICP-AES. The content of chromium in the filings of SRM 1227 was estimated as six times higher than the certified value due to the contamination of chromium in the file. To eliminate chromium contamination from the file, it was coated with WC-12Co using high-velocity oxygen-fuel (HVOF) spraying systems. After obtaining filings samples using the coated file, Cr content in four types of disk-form SRMs was determined by ICP-AES. The recoveries of Cr in the disk-form SRMs were in the range of 95.4-102.6%, with relative standard deviations from 0.43 to 3.0%. The Cr contents in the filings collected from the used outlet headers of the nuclear power plants using the flat file coated were in the range of 0.11-0.19%.

• 한국환경보건학회지
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• 제35권4호
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• pp.322-333
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• 2009

In this study, a measurement method was evaluated for the determination of polycyclic aromatic hydrocarbons (PAHs) in the ambient atmosphere. PAHs were sampled by high-volume samplers, and were then analysed with a GC/MS system. Particulate PAHs were collected on $8"{\times}10"$ quartz fiber filter, while vapor phase PAHs were adsorbed on polyurethane foam (PUF). Target compounds included a total of 36 PAHs, which are known to be frequently detected in the urban atmosphere. It was not necessary to clean-up samples before samples were analyzed using GC/MS, and the overall performance of the method was tested by a variety of quality control and quality assurance schemes. It is generally known that the clean-up procedure can negatively affect the recovery of samples. Precision and accuracy was evaluated using SRM provided by US NIST, and the results were generally satisfactory and reliable. However, the GC/MS method appeared not to be adequate for 6-rings PAHs, such as coronene, due to its lower sensitivity. In addition, collection efficiencies for low molecular compounds, such as 2-rings PAHs, were poor because of the lower retention volume of the PUF adsorbent. As a result, it was concluded that the method based on high-volume sampling and GC/MS analysis can give very reliable data by simultaneous sampling of both particulate and vapor phases for 3-rings to 5-rings PAHs of environmental concern.

• 약학회지
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• 제48권3호
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• pp.207-212
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• 2004

An analytic method was developed for the quantitation of $\Delta$$^{9}-$ tetrahydrocannabinol (THC) and 11-nor-9-carboxy THC (THC-COOH) in human hair. After hair samples were pulverized using Freezer Mill, deuterated internal standards were added and digested in 1 N NaOH at $100^{\circ}C$ water bath for 30 min. Digest solutions were extracted by 5 ml hexane：ethyl acetate (90：10) after acidification with acetic acid. The organic phase was evaporated under N 2 and derivatized by BSTFA (with 1% TMCS) at $85^{\circ}C$ for 45 min. The derivatized solution was separated on HP-5MS column ($30m{\times}0.25mm{\times}0.25mm$) and detected using EI-GC-MS with selective ion monitoring mode. The assay of calibration was ranged from 5 to 100 ng/50 mg hair ($r^2$＞0.99) for THC and THC-COOH. Within and between-run precision were calculated at 6, 30, 60 ng/50 mg hair with coefficients of variation less than 11%. Within and between run accuracies at the same concentrations were$\pm$14% and $\pm$30% of target for both analytes, respectively. Absolute and relative recovery at 10 and 100 ng were 60∼91％. The method was used to detect and quantify THC and THC-COOH in cannabis abuser's hairs (N = 16) and SRM (N=5, THC 1 ng/mg, NIST). We detected THC and THC-COOH in only one hair sample. In SRM, % accuracy was 93% (range 86∼103%) and precision (% CV) was 8.14. We began to set up a quantitative analysis of THC and THC-COOH using EI-GC-MS. Continuously, we need to modify and develop this method in order to apply for identification in cannanbis users' hair.

• 분석과학
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• 제15권5호
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• pp.417-426
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• 2002

반응셀이 장치된 유도결합플라스마 사중극자 질량분석기를 이용하여 자연적으로 존재하는 6개의 칼슘 동위원소의 검출특성에 관한 연구를 수행하였다. 동적반응셀 (dynamic reaction cell, DRC)장치를 이용한 실험에서 최적의 신호 대 잡음비를 얻기 위한 실험조건을 조사하였다. 본 실험을 통해서 반응기체로서 0.7 mL/min의 $NH_3$를 사용하고 rejection parameter (RPq)값을 0.6으로 사용함으로써, Ca의 질량위치인 m/z 40, 42, 43, 44, 46 그리고 m/z 48의 위치에서 잠재적인 간섭이온인 $Ar^+$, ${CO_2}^+$, ${NO_2}^+$, $CNO^+$ 등이 효과적으로 제거됨을 확인하였다. 검출한계는 동위원소 $^{40}Ca$, $^{42}Ca$, $^{43}Ca$, $^{44}Ca$, 및 $^{48}Ca$에 대해서 각각 1, 29, 169, 34, and 15 pg/g으로 얻을 수 있었다. 이러한 실험조건 하에서 국제비교분석을 위해서 영국의 LGC (Laboratory of the Government Chemistry, Queens Road, Teddington, England)로부터 공급된 합성식품분해물질 중의 Ca을 동위원소희석법을 적용하여 분석하였다. 동위원소희석법에 의한 측정의 불확도는 ISO/GUM과 EURACHEM지침서에 따라 평가하였다. 측정된 시료중의 Ca의 농도와 불확도는 ($66.4{\pm}1.2$) mg/kg이었다. 또한 본 실험방법의 유효성을 확인하기 위해 농도가 인증된 표준시료 NRCC (National Research Council of Canada)의 SLRS-3 (riverine water CRM)과 NIST (National Institute of Science and Technology)의 SRM1643d (trace element in water)를 분석하였다.