• 한국항공우주학회지
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• 제30권7호
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• pp.144-149
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• 2002

본 논문은 항공전자 시스템 통제와 항법 및 사격통제, 커시브 및 라스터 그래픽 심볼 생성 둥의 기능이 통합된 항공전자시스템컴퓨터(ASC) 개발을 위한 실시간 다중 프로세서 병렬처리 기법을 제안한다. 4개의 32비트 RISC 프로세서간 논리적 계층구조는 마스터-슬레이브 다중 처리방식의 비대칭 구조를 가지며, Interaction 정도는 시분할 공통 시스템 버스와 공유 메모리 등을 활용한 밀 결합 방식을 채택하고, 효율적인 버스 중재방식을 고안하여 최적성능을 구현하였다. 일련의 비행시험을 통해 개발된 ASC를 검증하였으며, 전기적 시험과 환경 및 전자기 간섭 등 관련시험 또한 수행하였다.

• Journal of Ginseng Research
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• 제40권4호
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• pp.382-394
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• 2016

Background: Ginsenosides are the characteristic and principal components which manifest a variety of the biological and pharmacological activities of the roots and rhizomes of Panax ginseng (GRR). This study was carried out to qualitatively and quantitatively determine the ginsenosides in the cultivated and forest GRR. Methods: A rapid and sensitive ultra-high-performance liquid chromatography coupled with diode-array detector and quadrupole/time of flight tandem mass spectrometry (UPLC-DAD-QTOF-MS/MS) was applied to the qualitative analysis of ginsenosides and a 4000 QTRAP triple quadrupole tandem mass spectrometer (HPLC-ESI-MS) was applied to quantitative analysis of 19 ginsenosides. Results: In the qualitative analysis, all ingredients were separated in 10 min. A total of 131 ginsenosides were detected in cultivated and forest GRR. The method for the quantitative determination was validated for linearity, precision, and limits of detection and quantification. 19 representative ginsenosides were quantitated. The total content of all 19 ginsenosides in the forest GRR were much higher than those in the cultivated GRR, and were increased with the growing ages. Conclusion: This newly developed analysis method could be applied to the quality assessment of GRR as well as the distinction between cultivated and forest GRR.

• Annals of Laboratory Medicine
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• 제38권6호
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• pp.545-554
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• 2018

Background: The increasing morbidity and mortality rates associated with Acinetobacter baumannii are due to the emergence of drug resistance and the limited treatment options. We compared characteristics of colistin-resistant Acinetobacter baumannii (CR-AB) clinical isolates recovered from patients with and without prior colistin treatment. We assessed whether prior colistin treatment affects the resistance mechanism of CR-AB isolates, mortality rates, and clinical characteristics. Additionally, a proper method for identifying CR-AB was determined. Methods: We collected 36 non-duplicate CR-AB clinical isolates resistant to colistin. Antimicrobial susceptibility testing, Sanger sequencing analysis, molecular typing, lipid A structure analysis, and in vitro synergy testing were performed. Eleven colistin-susceptible AB isolates were used as controls. Results: Despite no differences in clinical characteristics between patients with and without prior colistin treatment, resistance-causing genetic mutations were more frequent in isolates from colistin-treated patients. Distinct mutations were overlooked via the Sanger sequencing method, perhaps because of a masking effect by the colistin-susceptible AB subpopulation of CR-AB isolates lacking genetic mutations. However, modified lipid A analysis revealed colistin resistance peaks, despite the population heterogeneity, and peak levels were significantly different between the groups. Conclusions: Although prior colistin use did not induce clinical or susceptibility differences, we demonstrated that identification of CR-AB by sequencing is insufficient. We propose that population heterogeneity has a masking effect, especially in colistin non-treated patients; therefore, accurate testing methods reflecting physiological alterations of the bacteria, such as phosphoethanolamine-modified lipid A identification by matrix-assisted laser desorption ionization-time of flight, should be employed.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.355-355
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• 2016

There has been an explosive development of nanocrystal (NC) synthesis and application due to their composition-dependent specific properties. Despite the composition, shape, and size of NCs foremost determine their physicochemical properties, the surface state and molecule conjugation also drastically change their characteristics. To make practical use of NCs, it is a prerequisite to understand the NC surface state and the degree to which they have been modified because the reaction occurs on the interface between the NCs and the surrounding medium. We report in here an analysis method to identify conjugated ligands and their binding states on semiconductor nanocrystals based on their molecular information. Surface science techniques, such as time-of-flight secondary-ion mass spectrometry (ToF-SIMS) and FT-IR spectroscopy, are adopted based on the micro-aggregated sampling method. Typical trioctylphosphine oxide-based synthesis methods of CdSe/ZnS quantum dots (QDs) have been criticized because of the peculiar effects of impurities on the synthesis processes. Since the ToF-SIMS technique provides molecular composition evidence on the existence of certain ligands, we were able to clearly identify the n-octylphosphonic acid (OPA) as a surface ligand on CdSe/ZnS QDs. Furthermore, the complementary use of the ToF-SIMS technique with the FT-IR technique could reveals the OPA ligands' binding state as bidentate complexes.

• Korean Chemical Engineering Research
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• 제58권1호
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• pp.106-112
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• 2020

Analyzing vitamin D levels is important for monitoring health conditions because vitamin D deficiency is associated with various diseases such as rickets, osteomalacia, cardiovascular disorders and some cancers. However, vitamin D concentration in the blood is very low with optimal level of 75 nmol/L, making quantitative analysis difficult. The objective of this study was to develop a highly sensitive analysis method for vitamin D using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-MS). 25-hydroxyvitamin D (25(OH)D), which has been used as an indicator of vitamin D metabolites in human biofluids was chemically derivatized using a secosteroid signal enhancing tag (SecoSET) with powerful dienophile and permanent positive charge. The SecoSET-derivatized 25(OH)D provided good linearity (R² > 0.99) and sensitivity (limit of quantitation: 11.3 fmol). Chemical derivatization of deuterated 25-hydroxyvitamin D₃ (d₆-25(OH)D3) with SecoSET enabled absolute quantitative analysis using MALDI-MS. The highly sensitive method could be successfully applied into monitoring of quantitative changes of bioactive vitamin D metabolites after treatment with ketoconazole to inhibit 1α-hydroxylase reaction related to vitamin D metabolism in human breast cancer cells. Taken together, we developed a MALDI-MS-based platform that could quantitatively analyze vitamin D metabolites from cell products, blood and other biofluids. This platform may be applied to monitor various diseases associated with vitamin D deficiency such as rickets, osteomalacia and breast cancer.

• 한국운동역학회지
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• 제26권3호
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• pp.243-248
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• 2016

Objective: The aim of this study was to determine the kinematical characteristics of somersault with twist in the Lou Yun and Akopian motions and to provide useful information to gymnastic athletes in men's vault. Method: The study subjects were 12 male adult top athletes. After 12 trials (7 Lou Yun and 5 Akopian trials) filmed by using two digital high-speed camcorders set at 90 frames/sec, kinematical data were collected through the direct linear transformation (DLT) method. The mean differences in biomechanical variables were compared during the second flight upward phase. The kinematic characteristics of somersault with twist in the Lou Yun and Akopian motions were identified. Results: In Lou Yun motion, the vertical release velocity through horse breaking was not difficult to obtain, so the athletes had enough time to prepare for the twist. Therefore, the Lou Yun motion has an advantage to make a cat twist in the pike posture. In the Akopian motion, obtaining the horizontal velocity through horse pushing was so easy that the Akopian athletes attained a large angular impulse and angular momentum. Therefore, the Akopian motion has an advantage to making a tilt twist in the body tilting posture. Conclusion: This study suggests that gymnastic athletes should control their body segment movements in order to increase the twisting angular velocity of the whole body, which requires regulation of the longitudinal moment of inertia of the body. Moreover, athletes should prepare for the shoulder and hip twists early in order to make the landing position in advance.

• Journal of Applied Biological Chemistry
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• 제59권2호
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• pp.165-169
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• 2016

The quantitative analytical method for the bioactive substance, 3-cyano-4-methoxy-N-methyl-2-pyridone (ricinine) and an index compound, ricinoleic acid in castor plant (Ricinus communis) extract or oil was developed. For the determination of a pyridone alkaloid compound, ricinine, successive cartridge cleanup method combined with ultra-performance liquid chromatography was set up with $ENVI-Carb^{TM}$ (0.5 g) and $C_{18}$ SPE cartridges. Accuracy and precision were evaluated through fortification studies of one biopesticide (PE) at 10 and $100mg\;kg^{-1}$. Mean recoveries of ricinine were 98.7 and 96.0 % associated with less than 10 % RSD, respectively. For the determination of ricinoleic acid in castor extract and oil, saponification and methylation were optimized using gas chromatography-time of flight mass spectrometry. Recovery was more than 84.8 % associated with 6.2 % RSD after derivatization procedure. Both methodologies developed were applied to analyze real samples including three castor oil products and six commercially available biopesticides containing R. communis, collected at Korean market. The contents of ricinine and ricinoleic acid in most commercial biopesticides were less than the oil or extract contents indicated by label.

• 한국약용작물학회지
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• 제27권3호
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• pp.208-217
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• 2019

Background: In the present study, we identified two cytotoxic compounds from the root of Rumex crispus L. using a bioassay-based method. Methods and Results: Compared with the other fractions, the diethyl ether ($Et_2O$) fraction of R. crispus root extract exhibited the strongest of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging effect [scavenging concentration 50% $(SC_{50})=63.8{\pm}1.47{\mu}g/m{\ell}$], nitric oxide (NO) production inhibitory effect on the mouse macrophage cell line RAW264.7 [inhibitory concentration 50% $(IC_{50})=60.9{\pm}7.52{\mu}g/m{\ell}$] and cytotoxicity effect on the human hepatoma cell line, HepG2 [lethal concentration 50% $(LC_{50})=115.4{\pm}1.86{\mu}g/m{\ell}$]. According to the bioassay-based method, two cytotoxic compounds were purified from the $Et_2O$ fraction by using column chromatography and preparative high performance liquid chromatography (prep-HPLC). These two compounds were identified as parietin and chrysophanol by using nuclear magnetic resonance (NMR) and liquid chromatography quadruple time of flight mass spectrometry (LC-QTOF-MS). In addition, both parietin and chrysophanol exhibited a cytotoxicity effect on HepG2 cells, their $LC_{50}$ values were $169.1{\pm}17.67{\mu}M$ and $111.5{\pm}6.62{\mu}M$, respectively. Conclusions: Parietin and chrysophanol isolated from the $Et_2O$ fraction of the R. crispus root extract showed cytotoxicity in HepG2 cell.

• 대한원격탐사학회지
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• 제34권5호
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• pp.829-846
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• 2018

작황 모니터링은 농민들에게 최적의 작물 생산을 위한 농작업 관리 전략을 수립하는데 유용한 정보를 제공할 수 있다. 그러나 시료 채취에 의한 분석 등에 한정된 기존의 현장 모니터링 방법은 많은 시간과 노동력이 필요하다. 무인항공기는 고해상도 이미지를 신속하고 정기적으로 취득할 수 있는 장점이 있기 때문에 재배 면적, 생육인자, 생육이상 및 생산량 추정 등과 같은 작황 모니터링 분야에 효과적으로 활용될 수 있다. 또한, 위성과 비교하여 비행 고도가 낮아 흐린 날씨에서도 높은 화질의 영상을 수집할 수 있다. 본 연구는 작황 모니터링 분야에서의 무인항공기 활용 가능성을 검토하고 무인항공기 기반의 작황 정보 생산을 위한 적용방안을 제시하고자 하였다.

• Journal of Microbiology and Biotechnology
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• 제17권6호
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• pp.952-959
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• 2007

His-His-Leu (HHL), a tripeptide derived from a Korean soybean paste, is an angiotensin-I-converting enzyme (ACE) inhibitor. We report here a method of producing this tripeptide efficiently by expressing tandem multimers of the codons encoding the peptide in E. coli and purifying the HHL after hydrolysis of the peptide multimers. The HHL gene, tandemly multimerized to a 40-mer, was ligated with ubiquitin as a fusion gene (UH40). UH40 was inserted into vector pET29b; the UH40 fusion protein was then produced in E. coli BL21. The recombinant UH40 protein was purified by cation-exchange chromatography with a yield of 17.3mg/l and analyzed by matrixassisted laser desorption ionization (MALDI) time-of-flight (TOF) mass spectrometry and protein N-terminal sequencing. Leucine aminopeptidase was used to cleave a 405-Da HHL monomer from the UH40 fusion protein and the peptide was purified using reverse-phase high-performance liquid chromatography (HPLC) on a C18 HPLC column, with a final yield of 6.2mg/l. The resulting peptide was confirmed to be HHL with the aid of MALDI-TOF mass spectrometry, glutamine-TOF mass spectrometry, N-terminal sequencing, and measurement of ACE inhibiting activity. These results suggest that our production method is useful for obtaining a large quantity of recombinant HHL for functional antihypertensive peptide studies.