• 한국광물학회지
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• 제29권2호
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• pp.47-58
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• 2016

엽납석광석에 Fe-성분이 불순물로 작용하여 엽납석의 최종 산업제품의 품위를 저하시키고 있다. 엽납석광석에 존재하는 불순물을 광물-화학적으로 확인하고 마이크로웨이브와 자력선별을 이용하여 Fe 함량을 건식방법으로 감소시키고자 하였다. 광학현미경, XRD, XRF, SEM/EDS 및 EPMA 분석을 통하여 엽납석에 황철석과 적철석이 포함되어 있는 것을 확인하였다. 엽납석에 포함된 자형의 황철석은 열수용액에 의하여 형성되고, 용해 공동 구조는 황철석이 산성수에 의하여 부분적으로 용해되어 형성되는 것으로 사료된다. 그리고 퇴적 기원 구조를 보이는 동심원 구조의 적철석은 산성수에 포함되어 있는 $Fe^{3+}$가 침전되어 형성된 것으로 사료된다. 마이크로웨이브 가열과 자력선별 실험을 수행한 결과 Fe 제거율은 성산광산이 96%, 완도광산이 93%로 나타났다. 마이크로웨이브 가열과 자력선별은 저 품위 엽납석을 품위 향상시킬 수 있는 친환경적 방법이라 사료된다.

• Journal of Magnetics
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• 제22권2호
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• pp.266-274
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• 2017

In this paper, torques of two motors are compared by Finite Element Analysis (FEA). One has a symmetric rotor structure and the other has an asymmetric rotor structure. The comparison shows that the asymmetric rotor structured motor has reduced torque ripple compared to the symmetric. The torque of the compared motor models was analyzed by separating into magnetic torque and reluctance torque. Through the analysis of torque component separated, it is shown that the magnetic torque and the reluctance torque compensate each other in the motor with the asymmetric structure rotor. Here "compensate" means decrementing the effect of one or more harmonics. It is shown how this compensation appears between the magnetic torque and the reluctance torque by looking into back electro motive force (emf) and the relative permeability distribution of rotor core.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1992년도 추계학술대회
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• pp.22-25
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• 1992

화학적 이동성을 이용하여, 생체의 경우 지방질의 영상 혹은 물성분의 영상을 얻을 수 있다. 여러 가지 기술을 사용하여 분리된 성분의 자기공명 영상을 얻었다. Dixon의 방법은 두 번의 영상실험을 하여 지방질 영상과 물성분 영상을 구분할 수 있으며, 부분적 자기장의 불균질성에 영향을 적게 받고 다층 영상법에 용이하게 적용할 수 있다. CHESS와 SECSI 방법은 한번의 영상실험으로 물 또는 지방질 영상을 획득할 수 있다. 그러나 부분적 자기장의 불균질성에 영향을 많이 받으며, 다층영상법에 적용하기에는 어려운 점이 있다. 화학 성분의, 즉 지방질과 물성분의 분리의 척도가 되는 지방질 신호대 물성분신호 비에 있어 SECSI 방법이 가장 우수함을 보였다.

• Food Science and Biotechnology
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• 제15권2호
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• pp.220-226
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• 2006

Component having antioxidant activity on lard during heating was separated from hexane extract of spinach, and its characteristic chemical structure was speculated through nuclear magnetic resonance spectroscopy, liquid chromatography-mass spectrometry, and Fourier transform infrared spectrophotometry. Lard was heated with hexane-, ethyl ether-, ethyl acetate-, or ethanol extract of spinach at $180^{\circ}C$ for 20 hr. Hexane extract of spinach, having highest antioxidant activity on lard during heating, was fractionated by silicic acid column chromatography (SACC), and SACC fractions having higher antioxidant activity on lard during heating were further separated by thin layer chromatography (TLC). Isolated compound from SACC fractions of hexane extract of spinach by TLC had sugar moieties and benzene ring along with hydroxy, carbonyl, and alkyl groups in the structure.

• 대한원격탐사학회지
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• 제21권1호
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• pp.91-98
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• 2005

On board satellite magnetometer measures all possible magnetic components, such as the core and crustal components from the inner Earth, and magnetospheric, ionospheric and' its coupled components from the outer Earth. Due to its dipole and non-dipole features, separation of the respective component from the measurements is most difficult unless the comprehensive knowledge of each field characteristics and the consequent modeling methods are solidly constructed. Especially, regional long wavelength magnetic signals of the crust are strongly masked by the main field and dynamic external field and hence difficult to isolate in the satellite measurements. In particular, the un-modeled effects of the strong auroral external fields and the complicated behavior of the core field near the geomagnetic poles conspire to greatly reduce the crustal magnetic signal-to-noise ratio in the polar region relative to the rest of the Earth. We can, however, use spectral correlation theory to filter the static lithospheric and core field components from the dynamic external field effects that are closely related to the geomagnetic storms affecting ionospheric current disturbances. To help isolate regional lithospheric anomalies from core field components, the correlations between CHAMP magnetic anomalies and the pseudo-magnetic effects inferred from satellite gravity-derived crustal thickness variations can also be exploited, Isolation of long wavelengths resulted from the respective source is the key to understand and improve the models of the external magnetic components as well as of the lower crustal structures. We expect to model the external field variations that might also be affected by a sudden upheaval like tsunami by using our algorithm after isolating any internal field components.

• 한국자기공명학회논문지
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• 제15권1호
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• pp.54-68
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• 2011

$^1H$ nuclear magnetic resonance (NMR) spectroscopy of biological samples has been proven to be an effective and nondestructive approach to probe drug toxicity within an organism. In this study, ketoprofen toxicity was investigated using $^1H$-NMR spectroscopy coupled with multivariate statistical analysis. Histopathologic test of ketoprofen-induced acute gastrointestinal damage in rats demonstrated a significant dose-dependent effect. Furthermore, principal component analysis (PCA) derived from $^1H$-NMR spectra of urinary samples showed clear separation between the vehicle-treated control and ketoprofen-treated groups. Moreover, PCA derived from endogenous metabolite concentrations through targeted profiling revealed a dose-dependent metabolic shift between the vehicle-treated control, low-dose ketoprofen-treated (10 mg/kg body weight), and high-dose ketoprofen-treated (50 mg/kg) groups coinciding with their gastric damage scores after ketoprofen administration. The resultant metabolic profiles demonstrated that the ketoprofen-induced gastric damage exhibited energy metabolism perturbations that increased urinary levels of citrate, cis-aconitate, succinate, and phosphocreatine. In addition, ketoprofen administration induced an enhancement of xenobiotic activity in fatty oxidation, which caused increase levels of N-isovalerylglycine, adipate, phenylacetylglycine, dimethylamine, betaine, hippurate, 3-indoxylsulfate, N,N-dimethylglycine, trimethyl-N-oxide, and glycine. These findings demonstrate that $^1H$-NMR-based urinary metabolic profiling can be used for noninvasive and rapid way to diagnose adverse drug effects and is suitable for explaining the possible biological pathways perturbed by nonsteroidal anti-inflammatory drug toxicity.

• 대한의용생체공학회:의공학회지
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• 제30권5호
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• pp.373-380
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• 2009

In general, Independent component analysis (ICA) is a statistical blind source separation technique, used either in spatial or temporal domain. The spatial or temporal ICAs are designed to extract maximally independent sources in respective domains. The underlying sources for spatiotemporal data (sequence of images) can not always be guaranteed to be independent, therefore spatial ICA extracts the maximally independent spatial sources, deteriorating the temporal sources and vice versa. For such data types, spatiotemporal ICA tries to create a balance by simultaneous optimization in both the domains. However, the spatiotemporal ICA suffers the problem of source ambiguity. Recently, constrained ICA (c-ICA) has been proposed which incorporates a priori information to extract the desired source. In this study, we have extended the c-ICA for better analysis of spatiotemporal data. The proposed algorithm, i.e., constrained spatiotemporal ICA (constrained st-ICA), tries to find the desired independent sources in spatial and temporal domains with no source ambiguity. The performance of the proposed algorithm is tested against the conventional spatial and temporal ICAs using simulated data. Furthermore, its performance for the real spatiotemporal data, functional magnetic resonance images (fMRI), is compared with the SPM (conventional fMRI data analysis tool). The functional maps obtained with the proposed algorithm reveal more activity as compared to SPM.

• 지구물리와물리탐사
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• 제6권3호
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• pp.119-125
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• 2003

소형루프 전자탐사법은 다양한 현장에 성공적으로 적용되어온 효과적인 물리탐사법으로 특히 천부 지반조사나 환경오염대의 조사에 널리 사용되고 있다. 일반적으로 저유도상수(low induction number)대역에서 수행되는 소형루프 전자탐사에서는 주로 기하학적 수직탐사(geometric sounding)이 사용되어 왔으나, 근자에 이르러 정확한 2차장의 측정이 가능한 일체형의 다중 주파수 소형루프 전자탐사장비가 개발되면서, 주파수 수직탐사(frequency sounding)이 시도되고 있다. 본 논문에서는 간단한 2층구조에 대하여 수평루프 전자탐사 모델링을 수행하였다. 분석 결과 동상성분의 경우에는 주파수 수직탐사이 가능하지만, 이상성분의 경우에는 기하학적 수직탐사가 효과적인 것으로 확인되었다. 그러나 동상성분의 경우 신호의 크기가 이상성분에 비하여 미약하므로 국내에서와 같이 전기전도도가 낮고 전자기적 잡음 수준이 높은 지역에서는 적용이 곤란하다. 따라서 본 논문에서는 이상성분이 신호의 크기가 커 안정적 자료획득이 가능하며, 두 개의 주파수에 측정된 이상성분의 차가 동상성분과 같은 거동특성을 보인다는 점에 착안하여, 기존의 방법과는 다른 주파수 수직탐사 방법을 제시하고자 하였다. 또한 지하의 전기전도도를 비교적 잘 반영하는 겉보기 전도도를 정의하였다.

• Journal of Microbiology and Biotechnology
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• 제33권5호
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• pp.662-667
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• 2023

Allantoin is an abundant component of yams and has been known as a skin protectant due to its pharmacological activities. In previous methods for allantoin determination using high-performance liquid chromatography (HPLC), the separation was unsatisfactory. We herein developed a ¹H quantitative nuclear magnetic resonance (qNMR) method for quantification of allantoin in the flesh and peel of yams. The method was carried out based on the relative ratio of signals integration of allantoin to a certain amount of the internal standard dimethyl sulfone (DMSO₂) and validated in terms of specificity, linearity (range 62.5-2000 ㎍/ml), sensitivity (limit of detection (LOD) and quantification (LOQ) 4.63 and 14.03 ㎍/ml, respectively), precision (RSD% 0.02-0.26), and recovery (86.35-92.11%). The method was then applied for the evaluation of allantoin in flesh and peel extracts of four different yams cultivated in Korea.

• 자원리싸이클링
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• 제14권5호
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• pp.45-53
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• 2005

염산용액에서 전해생성 된 염소를 이용하여 폐프린터의 인쇄회로기판으로부터 동을 침출하는 연구를 수행하였다. 폐인쇄회로기판을 분쇄한 다음 입자크기가 $0.6{\sim}1.2mm$인 비자성 성분을 선별하여 침출실험을 행하였다. 비자성 분쇄물 중 금속성분의 평균함량은 45wt%이었으며, 동이 금속성분의 83.6wt% 이었다. 1 M 염산용액에서 전해생성된 염소에 의한 동의 침출반응은 전류밀도와 교반속도에 크게 영향을 받았다. 염산농도: 1 M, 전류밀도: $20mA/cm^2$, 침출온도: $50^{\circ}C$, 침출시간: 180분, 교반속도: 600rpm의 침출조건에서 동의 침출율은 98%로서 침출액에서 농도는 3.69g/l 해당하였다. 동의 침출반응에 대한 전해생성 된 염소의 이용율은 교반속도가 높고 인가전류밀도가 낮을 수록 높았다. 또한 침출반응 초기에는 알루미늄, 납, 주석 등의 기타금속 성분의 침출이 활발하고 동의 침출반응은 억제되었다.