• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.578-580
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• 2005

Energy distribution function for electrons in SF6-Ar mixtures gas used by MCS-BEq algorithm has been analysed over the E/N range 30~300[Td] by a two term Boltzmann equation and by a Monte Carlo Simulation using a set of electron cross sections determined by other authors, experimentally the electron swarm parameters for 0.2[%] and 0.5[%] $SF_6$-Ar mixtures were measured by TOF method, The results show that the deduced electron drift velocities, the electron ionization or attachment coefficients, longitudinal and transverse diffusion coefficients and mean energy agree reasonably well with theoretical for a rang of E/N values. The results obtained from Boltzmann equation method and Monte Carlo simulation have been compared with present and previously obtained data and respective set of electron collision cross sections of the molecules.

• 분석과학
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• 제30권6호
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• pp.379-389
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• 2017

In this study, we set up an analytical method that can be used for rapid and accurate determination of representative isoquinoline alkaloids in medicinal plants using UPLC-ESI-Q-TOF MS (ultra pressure liquid chromatography-electrospray ionization-quadrupole-time-of-flight mass spectrometry). The compounds were eluted on a C18 column with 0.1 % formic acid and acetonitrile, and separated with good resolution within 13 min. Each of the separated components was characterized by precursor ions (generated by ESI-Q-TOF) and fragment ions (produced by collision-induced dissociation, CID), which were used as a reliable database. We also performed method validation: analytes showed excellent linearity ($R^2$, 0.9971-0.9996), LOD (5-25 ng/mL), LOQ (17-82 ng/mL), accuracy (91.6-97.4 %) as well as intra- and inter-day precisions (RSD, 1.8-3.2 %). In the analysis of Chelidonium majus L., magnoflorine, coptisine, sanguinarine, berberine and palmatine were detected by matching retention times and characteristic fragment ion patterns of reference standards. We also confirmed that, among the quantified components, coptisine was present in the highest quantity. Furthermore, alkaloid profiling was carried out by analyzing the fragment ion patterns corresponding to peaks of unknown components. In this manner, protopine, chelidonine, stylopine, dihydroberberine, canadine, and nitidine were tentatively identified. We also proposed the molecular structure of the fragment ions that appear in the mass spectrum. Therefore, we concluded that our suggested method for the determination of major isoquinoline alkaloids by UPLC-Q-TOF can be useful not only for quality control, but also for rapid and accurate investigation of phytochemical constituents of medicinal plants.

• 한국정보통신학회논문지
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• 제16권1호
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• pp.1-12
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• 2012

본 논문에서는 고부가가치의 디지털 홀로그램 콘텐츠를 저작하여 새로운 디지털 홀로그램 콘텐츠를 확보하는 방법을 제안한다. 깊이정보는 스테레오 정합방식으로 획득한 시차정보로부터 얻은 깊이정보와 TOF (time-of-flight) 방식의 깊이카메라로 촬영한 깊이정보를 모두 사용한다. 각 종류의 깊이정보와 변환방법을 사용하여 깊이정보를 변환하거나 합성하고 이를 CGH 방법으로 연산하여 디지털 홀로그램을 획득한다. 또한 CGH 연산으로 획득한 디지털 홀로그램의 선형성을 기반으로 기 생성된 디지털 홀로그램 콘텐츠를 합성하여 새로운 디지털 홀로그램 콘텐츠를 획득하는 방법도 제시한다. 제안한 방법을 다양한 깊이정보와 디지털 콘텐츠를 대상으로 실험하여 이 방법이 디지털 홀로그램 콘텐츠의 저작방법으로 효과적임을 보인다.

• Journal of Magnetics
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• 제19권2호
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• pp.185-191
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• 2014

In this study we evaluated that flow rate changes affect the (time of flight) TOF image and contrast-enhanced (CE) in a three-dimensional TOF angiography. We used a 3.0T MR System, a nonpulsatile flow rate model. Saline was used as a fluid injected at a flow rate of 11.4 cm/sec by auto injector. The fluid signal strength, phantom body signal strength and background signal strength were measured at 1, 5, 10, 15, 20 and 25-th cross-section in the experienced images and then they were used to determine signal-to-noise ratio and contrast-to-noise ratio. The inlet, middle and outlet length were measured using coronal images obtained through the maximum intensity projection method. As a result, the length of inner cavity was 2.66 mm with no difference among the inlet, middle and outlet length. We also could know that the magnification rate is 49-55.6% in inlet part, 49-59% in middle part and 49-59% in outlet part, and so the image is generally larger than in the actual measurement. Signal-to-noise ratio and contrast-to-noise ratio were negatively correlated with the fluid velocity and so we could see that signal-to-noise ratio and contrast-to-noise ratio are reduced by faster fluid velocity. Signal-to-noise ratio was 42.2-52.5 in 5-25th section and contrast-to-noise ratio was from 34.0-46.1 also not different, but there was a difference in the 1st section. The smallest 3D TOF MRA measure was $2.51{\pm}0.12mm$ with a flow velocity of 40 cm/s. Consequently, 3D TOF MRA tests show that the faster fluid velocity decreases the signal-to-noise ratio and contrast-to-noise ratio, and basically it can be determined that 3D TOF MRA and 3D CE MRA are displayed larger than in the actual measurement.

• Natural Product Sciences
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• 제17권3호
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• pp.202-205
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• 2011

The Angelica root has been used as a medicinal herb in many Asian countries including Korea, China, and Japan. Angelica gigas, A. sinensis, and A. acutiloba have been considered as Angelicae radix in Korean, Chinese, and Japanese Pharmacopoeia, respectively. Since the origins of Angelicae radix differ from country to country, there is a need to develop an efficient analytical method to identify the origin of the Angelica root. In order to obtain chemical fingerprints, three different Angelicae Radices were analyzed by direct analysis in real time mass spectrometry (DART-MS). Significantly different DART-MS spectra were observed from three different species of Angelicae Radix. Strong peaks of decursin or decusinol angelate, and its dimer were exclusively found from A. gigas. Ligustilide and linoleic acid were detected as the major component from A. acutiloba. The strongest ligustilide peak was observed from A. sinensis. DART-MS fingerprinting is a promising method for the rapid identification and/or quality control of Angelicae Radix.

• 분석과학
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• 제18권6호
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• pp.483-490
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• 2005

TOF 비행시간을 이용한 에어로졸 질량분석기에서 질량분석기의 분해능은 발생하는 이온의 초기에너지와 이온이 움직이는 진행방향에 따라 달라진다. 고출력 펄스형 레이저에 의하여 에어로졸로부터 용발되어 이온화된 원소들은 다른 속도로 사방으로 퍼져 나가게 되어 분해능 저하를 초래하는데 이를 방지하기 위해서 1차 가속된 이온들을 서로 다른 에너지로 후집속하여 같은 시간에 이온센서에 도달하도록 하는 장치에 대하여 연구를 수행하였다. 후집속 전위를 $90^{\circ}$ 방향으로 진행하는 이온을 중심으로 서로 다른 방향으로 걸어 줌으로써 TOF 영역을 지나 센서로 도입되는 이온의 도착 시간이 크게 개선되었음을 알 수 있었으며, 이를 실증하기 위하여 레이저 유도 이온을 만들고 후집속 장치를 구성하여 최적의 시간지연시간 및 전압 조건을 도출하여 그 성능을 증가시켰다.

• 방송공학회논문지
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• 제19권4호
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• pp.533-546
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• 2014

본 논문은 Time-of-Flight(ToF) 깊이 카메라와 DSLR을 이용한 사진측량 기반의 복합형 카메라시스템 구성방법을 제안한다. ToF 깊이 카메라는 깊이 정보를 실시간으로 출력하는 장점이 있지만 제공되는 명암 영상의 해상도가 낮고 획득한 깊이 정보가 물체의 표면상태에 민감하여 잡음이 발생하는 단점이 있다. 따라서 깊이 카메라를 이용한 입체 모델 생성을 위해선 깊이 정보의 보정과 함께 고해상도 텍스처맵을 제공하는 복합형 카메라의 구성이 필요하다. 이를 위해 본 논문은 상대표정을 수행하여 깊이 카메라와 DSLR의 상대적인 기하관계를 추정하고 공선조건식 기반의 역투영식을 이용하여 텍스처매핑을 수행한다. 성능검증을 위해 기존 기법의 모델 정확도와 텍스처매핑 정확도를 비교 분석한다. 실험결과는 제안 기법의 모델 정확도가 더 높았는데 이는 기존 기법이 깊이 카메라의 잡음이 있는 3차원 정보를 기준점으로 사용하여 절대표정을 수행한 반면에 제안 기법은 오차정보가 없는 두 영상간의 공액점을 이용했기 때문이다.

• Journal of Ginseng Research
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• 제41권1호
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• pp.10-22
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• 2017

Background: Asian ginseng and American ginseng are functional foods that share a close genetic relationship and are well-known worldwide. This article aims to investigate the correlation between morphological characteristics and the inherent quality of Asian and American ginsengs. Methods: In this study, an ultra-HPLC-quadrupole/time-of-flight MS (UHPLC-Q/TOF-MS) method was established for the quantitative analysis of 45 ginseng samples. The method developed for determination was precise and accurate. Results: The results showed that Asian ginseng samples with the same growing time (with the same or similar number of stem scars) that had a thinner main root, a longer rhizome and more branch roots contained greater amounts of ginsenosides. For American ginseng, two tendencies were observed in the relationship between the diameter of the main root and contents of ginsenosides. One tendency was that samples with thinner main roots tended to contain higher levels of ginsenosides, which was observed in the samples sold under the commercial name pao-shen. Another tendency was that samples with thicker main roots contained higher contents of ginsenosides, which was observed in the samples sold under the commercial name pao-mian, as well as in samples of American ginseng cultivated in Jilin, China. Conclusion: An approach using ultra-HPLC-quadrupole/time-of-flight MS was successfully established to link morphology and active components for evaluating the quality of Asian and American ginsengs. Clear correlation between visible morphological features and quality of Asian and American ginsengs was found. People can see the difference; this means consumers and vendors can evaluate ginseng by themselves.

• Biomolecules & Therapeutics
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• 제21권6호
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• pp.470-475
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• 2013

Ultraviolet (UV) radiation is a major environmental factor that leads to acute and chronic reactions in the human skin. UV exposure induces wrinkle formation, DNA damage, and generation of reactive oxygen species (ROS). Most mechanistic studies of skin physiology and pharmacology related with UV-irradiated skin have focused on proteins and their related gene expression or single-targeted small molecules. The present study identified and analyzed the alteration of skin metabolites following UVB irradiation and topical retinyl palmitate (RP, 5%) treatment in hairless mice using direct analysis in real time (DART) time-of-flight mass spectrometry (TOF-MS) with multivariate analysis. Under the negative ion mode, the DART ion source successfully ionized various fatty acids including palmitoleic and linolenic acid. From DART-TOF-MS fingerprints measured in positive mode, the prominent dehydrated ion peak (m/z: 369, M+H-$H_2O$) of cholesterol was characterized in all three groups. In positive mode, the discrimination among three groups was much clearer than that in negative mode by using multivariate analysis of orthogonal partial-least squares-discriminant analysis (OPLS-DA). DART-TOF-MS can ionize various small organic molecules in living tissues and is an efficient alternative analytical tool for acquiring full chemical fingerprints from living tissues without requiring sample preparation. DART-MS measurement of skin tissue with multivariate analysis proved to be a powerful method to discriminate between experimental groups and to find biomarkers for various experiment models in skin dermatological research.

• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 2002년도 Proceedings
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• pp.367-369
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• 2002

We have designed ramp profile excitation pulse based on the Shinnar-Le Roux (SLR) algorithm. The algorithm provides many advantages to pulse designers. The first advantage is the freedom of deciding the amplitudes, frequencies, and ripple sizes of stopband, passband, and transition band of pulse profile. The second advantage is the freedom of deciding the pulse phase, more specifically, minimum phase, linear phase, maximum phase, and any phase between them. The minimum phase pulse is the best choice in the case of 3D TOF, because it minimizes the echo time, which implies the best image quality in the same MR examination condition. In addition, the half echo technique is slightly modified in our case. In general, using the half echo technique means that the acquired data size is half and the rest part can be filled with complex conjugate of acquired data. But in our case, the echo center is just shifted to left, which implies the reduction of echo time, and the acquired data size is the same as the one without using the half echo technique. In this case, the increase of right part of data leads to improvement of the resolution and the decrease of left part of data leads to decrease of signal to noise ratio. Since in the case of 3D TOF, the signal to noise ratio is sufficiently high and the resolution is more important than signal to noise ratio, the proposed method appears to be significantly affective and gives rise to the improved high resolution angiograms.