• 한국기계가공학회지
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• 제20권11호
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• pp.52-59
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• 2021

Titanium alloy (Ti-alloy) is widely used as a material for core parts of aircraft structures and engines that require both lightweight and heat-resistant properties owing to their high specific stiffness. Most parts used in aircraft have I-, L-, and H-shaped thin-walled structures for weight reduction. It is difficult to machine thin-walled structures owing to vibrations and deformations during machining. In particular, cutting tool damage occurs in the corners of thin-walled structures owing to the rapid increase in cutting force and vibration, and machining quality deteriorates because of deep tool marks on machined surfaces. In this study, milling experiments were performed to derive an effective method for machining a L-shaped thin-walled structure with Ti-alloy (Ti-6Al-4V). Three types of machining experiment were performed. The surface quality, tool wear, cutting force, and vibration were analyzed comprehensively, and an effective machining method in terms of tool life and machining quality was derived.

• 한국미생물·생명공학회지
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• 제24권6호
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• pp.738-742
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• 1996

An efficient packed-bed type biofilm reactor charged with immobilized phototrophs was developed to treat organic wastewater at an extremely high volumetric loading rate. The packed bed reactor (PBR) charged with porous ceramic beads was superior to a fluidized-bed reactor suspended with activated carbon powders in terms of many aspects such as BOD removal efficiency, operational stability, and overall economics. For wastewater with BOD concentration as high as 20, 000mg/l, the BOD removal efficiency was maintained above 90% when the hydraulic retention time (HRT) was longer than 1 day. The allowable volumetric BOD loading rate of this reactor (20gBOD/l day) is more than ten-folds higher than that of an ordinary activated sludge method. The behaviour of the reactor was represented well by a Monod type kinetic equation with a maximum specific BOD loading rate(P) of 22.2gBOD/l day and a half saturation constant(K$_{s}$) of 1, 750 mgBOD/l.

• 대한약학회:학술대회논문집
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• 대한약학회 2003년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.2-2
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• pp.220.1-220.1
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• 2003

A sensitive and selective liquid chromatographic method for the determination of carvedilol in human plasma was developed and validated. Analytes were separated on a XTerra C18 column with acetonitrile-methanol-30 mM KH$_2$PO$_4$ (pH 2.5) (20 : 20 : 60, v/v/v), as mobile phase. One mL plasma were pipetted into glass tubes and spiked with 0.05 mL of internal standard solution. After adding 7 mL of diethyl ether, the plasma sample was then shacked for 15 min. A centrifuged upper layer was back-extracted with 150 uL of 0.05 M sulfuric acid. (omitted)

• Mass Spectrometry Letters
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• 제4권1호
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• pp.18-20
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• 2013

Headspace solid phase micro-extraction gas chromatography/flame ionization detection (HS-SPME-GC/FID) method was compared with headspace gas chromatography/mass selective detection (HS-GC/MS). Organic solvent-spiked urine as well as urine samples from workspace was analyzed under optimal condition of each method. Detection limit of each compound by HS-SPME-GC/FID was $3.4-9.5{\mu}g/L$, which enabled trace analysis of organic solvents in urine. Linear range of each organic solvent was $10-400{\mu}g/L$, with fair correlation coefficient between 0.992 and 0.999. The detection sensitivity was 4 times better than HS-GC/MS in selected ion monitoring (SIM) mode. Accuracy and precision was confirmed using commercial reference material, with accuracy around 90% and precision less than 4.6% of coefficient of variance. Among 48 urine samples from workplace, toluene was detected from 45 samples in the range of $20-324{\mu}g/L$, but no other solvents were found. As a method for trace analysis, SPME HS GC/FID showed high sensitivity for biological monitoring of organic solvent in urine.

• Parasites, Hosts and Diseases
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• 제44권2호
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• pp.133-138
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• 2006

This experiment was undertaken to screen the acaricidal effects of herb essential oils (pennyroyal, ylang ylang, citronella, lemon grass, tea tree, and rosemary) at different doses (0.1, 0.05, 0.025, 0.0125, and $0.00625{\mu}l/cm2$) and exposure times (5, 10, 20, 20, 30 and 60 min) on house dust mites Dermatophgoides farinae and D. pteronyssinus. The most effective acaricidal components of pennyroyal (Mentha pulegium) were analyzed using a gas chromatography-mass spectrometer (GC-MS). Of these essential oils, the most effective was pennyroyal, which is composed essentially of pulegone (> 99%), at a dose of $0.025{\mu}l/cm^2$, which at an exposure time of 5 min killed more than 98% of house dust mites. In the pennyroyal fumigation test, the closed method was more effective than the open method and maximum acaricidal effect was 100% at $0.025{\mu}l/cm^2$, 60 min. The results show that herb essential oils, in particular, pennyroyal was proved to have potent acaricidal activity.

• 공업화학
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• 제10권4호
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• pp.568-575
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• 1999

백금족 금소과 규산염을 포함하는 자동차 폐촉매 내의 백금족 금속과 주요 성분들을 ICP-AES로 동시에 분석하기 위한 두 종류의 전처리 방법이 비교되었다. HF, $HNO_3$, HCl, $HClO_4$, $H_2O_2$, 및 $H_3BO_3$ 등의 혼합산의 다양한 조합을 사용하여 열판(hot plate) 용해법과 밀폐용기를 사용하는 극초단파(microwave) 가압-가열법을 비교 검토하였다. 전통적인 열판 용해법보다 밀폐용기를 사용한 극초단파 가압-가열법이 화수율, 분석시간 및 사용하는 양 등의 측면에서 상대적으로 우수한 결과를 나타내었고, 0.25 g의 폐촉매 시료에 대하여 HF 2 mL, $HNO_3$2 mL, 그리고 HCl 6 mL를 사용하여 200 psi(13.79 bar), $180^{\circ}C$ 조건에서 1시간 동안 가열한 후, 5% (w/v) $H_3BO_3$ 16 mL를 사용하여 20 psi(1.38 bar), $100^{\circ}C$ 조건에서 10분간 가열한 다음, 왕수 10 mL로 열판에서 두 번 반복하여 처리하는 것이 백금족 금속의 회수율 측면에서 가장 좋은 결과를 가져왔고(XRF 분석 대비 85~110%), 이 방법은 2% 이내의 상대 표준 편차를 보임으로써, 자동차 폐촉매의 일상적인 분석기법으로서의 충분한 가능성을 보였다.

• Bulletin of the Korean Chemical Society
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• 제25권2호
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• pp.213-215
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• 2004

An indirect, sensitive and accurate method for the determination of trace amounts of hydrazine is described. The method is based on the oxidation of hydrazine by a known excess of iodate in the presence of hydrochloric acid. The unreacted iodate is used in the oxidation of hydroxylamine to nitrite. Sulfanilic acid is diazotized by the nitrite formed. The resulting diazonium ion is coupled with N-(1-naphthyl)ethylenediamine to form a stable azo dye, which shows an absorption maximum at 540 nm. Hydrazine can be determined in the range of 20-400 ng $mL^{-1}$ with a detection limit of 3.1 ng $mL^{-1}$. The relative standard deviation for 50, 200 and 400 ng $mL^{-1}$ of hydrazine is 2, 1.5 and 1.3%, respectively (n = 10). The method was applied to the determination of hydrazine in water samples.

• 화훼연구
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• 제19권3호
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• pp.127-138
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• 2011

운간초의 분화 품질을 향상시키기 위하여 'Kumoma'와 'Kumoma-Gusa' 두 품종의 생장과 개화에 미치는 영향을 구명하고자 식물생장억제제 (PGRs) 4종을 처리하였다. 식물생장억제제 종류와 처리농도는 paclobutrazol (10, 20, 40, $80mg{\cdot}L^{-1}$), flurprimidol (5, 10, 20, $40mg{\cdot}L^{-1}$), daminozide (500, 1000, 2000, $4000mg{\cdot}L^{-1}$), chlormequat (50, 100, 200, $400mg{\cdot}L^{-1}$)이고 엽면살포와 토양관주 방법으로 처리하였다. Paclobutrazol $40mg{\cdot}L^{-1}$ 처리는 운간초의 두 품종에서 초장과 화경장을 줄이는데 효과적이었다. 'Kumoma' 품종에서, paclobutrazol $40mg{\cdot}L^{-1}$ 엽면살포와 토양관주 처리방법은 초장을 각각 12.6, 12.5 cm로, 화경장은 3.4, 3.3 cm로 줄일 수 있었다. 'Kumoma-Gusa' 품종에서는 paclobutrazol 토양관주는 처리 농도가 증가함에 따라 초장은 13.2-10.7 cm, 화경장은 3.9-2.0 cm까지 줄일 수 있었지만 꽃의 수는 대조구와 비교했을 때 현저하게 감소하여서 20개까지 감소하였다. Flurprimidol $20mg{\cdot}L^{-1}$ 스프레이와 토양관주 처리는 두 품종 모두 초장과 화경장을 줄일 수 있었다. 'Kumoma' 품종에서 flurprimidol $10mg{\cdot}L^{-1}$ 스프레이 또는 토양관주 처리는 개화 품질을 향상시킬 수 있었고 대조구와 비교해 꽃의 수는 44.7개 이상, 출하 일수는 5일 정도 빨리 출하 할 수 있었다. 'Kumoma-Gusa' 품종에서 PGRs처리에 의한 초장과 화경장 억제효과가 가장 큰 것은 paclobutrazol $80mg{\cdot}L^{-1}$과 flurprimidol $40mg{\cdot}L^{-1}$ 이었고 paclobutrazol과 flurprimidol 스프레이와 토양관주 처리에서 각각, 초장은 10.7, 9.9 cm, 화경장은 2.0, 1.5 cm 로 생장 억제효과가 가장 큰 것을 알 수 있었다. 그러나 flurprimidol $40mg{\cdot}L^{-1}$ 토양관주 처리에서 출하일수는 농도에 따라 3-13일 정도 대조구보다 늦어졌고 꽃의 수는 15.6개로 가장 적은 것을 관찰 할 수 있었다. 두 품종 모두에서 daminozide 처리는 초장과 화경장이 줄어들지 않았지만 'Kumoma' 품종에서는 대조구와 비교했을 때 꽃의 수가 증가하였다. Chlormequat 처리는 paclobutrazol 과 flurprimidol 처리와 비교했을 때 화경장 감소효과는 작았고 처리 식물의 잎은 다른 처리에 비해 연한 녹색을 보여주었다. 두 품종 모두에서 chlormequat 과 daminozide 처리는 생육과 개화 품질에 효과적으로 영향을 주지는 않았지만 꽃의 수는 모든 처리농도에서 41개 이상을 보여주었고, 'Kumoma-Gusa' 품종에 chlormequat 토양관주 처리는 최대 꽃의 수 63개를 볼 수 있었다. 이번 결과들은 paclobutrazol 과 flurprimidol 처리가 운간초 분화의 품질 향상을 위한 화경장의 생육을 조절하는 생장억제제로서 사용 될 수 있음을 보여 주었고, 'Kumoma' 품종에서는 paclobutrazol $40mg{\cdot}L^{-1}$ 스프레이는 생육특성을, flurprimidol $10mg{\cdot}L^{-1}$ 토양관주 방법은 개화관련 특성의 품질을 향상시키는 생장억제제의 농도로 추천 될 수 있고, 'Kumoma-Gusa' 품종에서는 flurprimidol $20mg{\cdot}L^{-1}$ 스프레이와 flurprimidol $5mg{\cdot}L^{-1}$ 토양관주 방법이 운간초 분화의 생육특성과 개화품질을 향상시키는 생장억제제의 농도로 추천 될 수 있다.

• 핵의학기술
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• 제27권1호
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• pp.29-35
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• 2023

Purpose The concentration of PSA (Prostate Specific Antigen) after radical prostatectomy in prostate cancer patients is a predictor of biochemical recurrence, and the AUA (American Urological Association) is defined as biochemical recurrence when the concentration of PSA is measured at 0.2 ng/mL or more, and when the concentration is measured at 0.2 ng/mL or more at the retest. This standard is also applied our hospital. In this laboratory, the PSA reagent using IRMA (Immunoradiometric Assay) is used, and the sensitivity at a very low value was not as good as the reagent used in the department of laboratory medicine. This study aims to increase the reliability of the results by improving the precision and sensitivity of very low values. Materials and Methods As a reagent for the study, PSA reagent using IRMA was used. As a method to improve the precision and sensitivity of very low values, a variation method on the serum volume(25 uL, 50 uL, 100 uL, 200 uL) was studied, and variation usefulness evaluation was conducted. The evaluation items were compared the results of precision, analytical sensitivity, recovery rate, dilution test, high-dose hook effect test, parallel test and very low concentration values(n = 20). Results The validation results were displayed in the order of 25 uL, 50 uL, 100 uL, 200 uL. As the serum volume increased, it was confirmed that CV (Coefficient of Variation)(%) improved. Analytical sensitivity(ng/mL) was 0.038, 0.041, 0.017, 0.015 and recovery rate(%) was 101±3, 101±3, 99±2, 97±4. very low concentration values(ng/mL) between each volume(n=20) were 0.135±0.068, 0.076±0.050, 0.048±0.034, 0.046±0.034. and high dose hook effect appeared as the serum volume increased. Conclusion Through the variation usefulness evaluation, it was confirmed that as the serum volume increased, the precision and sensitivity improved at very low concentration values. However, it is necessary to pay special attention to the occurrence of high-dose hook effect as the serum volume increases. In the case of tests that requires very low concentration values, it is thought that the reliability of the result will be increased if the variation method is properly used after the variation usefulness evaluation.

• 한국식품영양학회지
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• 제17권3호
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• pp.254-259
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• 2004

Primer 20가지로 Listeria spp.에 대해 screening을 하여 병원균인 L. monocytogenes를 구별하게 하는 RAPD-PCR의 band pattern을 나타내는 10-mer random primer가 OPG-13이 라는 것을 알았다. OPG-13은 GC%가 70%이므로 계산상으로는 annealing 온도가 34$^{\circ}C$이다. 32～36$^{\circ}C$까지 다섯 가지의 온도로 annealing한 결과 L. monocytogenes만이 갖는 특정한 크기의 band가 역시 34$^{\circ}C$에서 형성됨을 알아냈고, 34$^{\circ}C$를 annealing 온도로 정하였다. Line 1부터 4까지 1. monocytogenes ATCC15313, 19111, 19112, 19113은 2개의 700 bp와 1500 bp band를 형성하였고 그 밖의 Listeria spp.들 Line 6부터 11까지 L. ivanovii ATCC 19119, L. grayi ATCC19120, L. murrayi ATCC25401, L. innocua ATCC33090, L. welshimeri ATCC35897, L. seeligeri ATCC35967은 약 2,000 ～ 2,300 bp크기 한 개의 band를 보여 병원성 균과 비병원성 균이 매우 확실하게 구분되는 band pattern이 나타나는 이러한 결과로 10-mer random primer인 OPG-13을 이용한 RAPD-PCR 방법이 병윈균인 L. monocytogenes를 검색하는데 이용될 수 있음을 확인할 수 있었다.