• 분석과학
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• 제10권6호
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• pp.439-444
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• 1997

압전 세라믹스 [$Pb(ZrTi)O_3$] 소재에 대하여 신속하고 정확하게 분석할 수 있는 X-선 형광분석용 표준물질 12종을 제작하였다. 특히 매질효과의 제거, 보관성, 균질성 등을 고려하여 융제($Li_2B_4O_7/LiBO_2=4/1$)로 시료를 16배 희석하여 제작하였다. 네 곳의 분석기관에서 X-선 형광분광기로 12개의 표준물질에 포함된 11 원소에 대하여 검정곡선을 작성해 본 결과 PbO, $ZrO_2$, $TiO_2$, SrO, $WO_3$, $La_2O_3$, $Cr_2O_3$, MgO, $Nb_2O_5$, $MnO_2$들은 correlation factor가 0.998을 넘는 대단히 좋은 직선을 얻었다. 그러나 ZnO의 correlation factor는 0.977로 비교적 낮았으며, 이는 표준시료 중 ZnO의 함량이 10ppm 정도로 낮았기 때문이다. 본 연구에서 제작한 XRF 분석용 표준물질을 이용하면 PZT 중의 주 부성분 원소의 함량을 간편하고 신속 정확하게 분석결과를 얻을 수 있다.

• Journal of Radiation Protection and Research
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• 제20권4호
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• pp.275-283
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• 1995

${\alpha}$-선 액체섬광계수기인 PERALS(Photon Electron Rejecting Alpha Liquid Scintillation) 분광기를 측정수단으로 사용하고 용매추출법을 이용하여 지하수중의 $^{222}Rn$과 $^{226}Ra$ 분석기술을 확립하였다. 이로서 기존의 액체섬광계수법에서 문제가 되었던 고준위 백그라운드, 낮은 에너지 분해능 및 소광현상(quenching) 문제를 극복하였다. 표준 $^{226}Ra$ 물질인 NIST SRM 4966을 이용하여 $^{226}Ra$의 방사능을 분석한 결과 정밀도는 약 1%, 정확도는 약 3%로 나타났으며, $pH 2{\sim}10$사이에서 pH에 따른 Rn 추출의 재현성은 7%이었다. 계측시간 10시간을 기준으로 $^{222}Rn$ 과 $^{226}Ra$의 검출 하한 값은 각각 $0.42 pCi/{\iota},\;0.016 pCi/{\iota}$이었다. 지하수중의 Ra과 Rn의 방사능을 측정하기 위하여 전국 17곳의 온천수를 시험분석대상으로 택하였다. Rn의 방사능은 90에 서 $5200pCi/{\iota}$까지의 범위를 보이며, 평균 방사능은 $1470pCi/{\iota}$이었다. Ra의 방사능은 강원도 한 곳에서 $97.9pCi/{\iota}$의 높은 수치를 보이며, 이를 제외한 평균함량은 $1.14pCi/{\iota}$이었다.

• 한국환경보건학회지
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• 제28권3호
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• pp.64-71
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• 2002

Hair provides important information about the body's mineral status. Therefore, we have studied the trace elemental distribution in human hair under different inhalation and ingestion environment using neutron activation analysis (NAA). NAA is a powerful analytical method which can be used successfully to determine trace elements in environmental and biological materials. Total diet and six different herbal medicine were analysed to study ingestion environment. Airborne dust in foundry was analysed and compared with outdoor dust to study inhalation environment. Human hairs of common person, herbal medicine taker and foundry worker were analysed to estimate the trace elemental distribution of people under different inhalation and ingestion environment. Analytical results show that herbal medicines contain higher micronutrients such as Ca, Mg, Mn and Cu that total diet and airborne dust in foundry has high Cr. The concentration of Ca, Mg and Mn in hair of herbal medicine taker is two times higher than in hair of common person and Cr con-centration in hair of foundry worker is about three times higher than in hair of common person. These results show that NAA can be used importantly to monitor human health through biological and environmental samples.

• 한국전기전자재료학회논문지
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• 제23권5호
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• pp.408-412
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• 2010

The single-phase switched reluctance motor(SRM) generates the positive torque in the restricted section. So, it can not started by itself and the torque ripple is heavier than poly-phase. For self-starting and fixing rotating direction, the rotor should be placed at the rising inductance slope when stationary. The parking permanent magnet locates the rotor in the fixed position, which can be started by it-self. It is very simple and cost effective but has some drawbacks. It affects the rotor during the operation, so the characteristics of motor, such as a torque, speed, and ripple are changed to go bad. This paper presents the detent torque of parking magnet starting device through the finite element analysis and experiments. The finite element analysis is performed at incremental rotor positions over one detent torque cycle for any one pole. The prototype, fabricated in the previous research, is used for the experiments. The inductance, instant torque, and detent torque are calculated using the terminal voltage and phase current. Finally, the finite element analysis result and the experiment result are compared for analysis and validity.

• 한국축산식품학회지
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• 제41권2호
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• pp.335-342
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• 2021

Vitamin B12 deficiency may lead to serious health issues in both infants and adults. A simple analytical method involving sample pretreatment with enzyme, followed by cyanide addition under acidic conditions; separation on an immunoaffinity column; and high-performance liquid chromatography (HPLC) was developed for the rapid detection and quantitation of vitamin B12 in powdered milk. Detection limit and powdered milk recovery were determined by quantitative analysis. The limits of detection and quantitation were 2.71 and 8.21 ㎍/L, respectively. Relative standard deviations of the intra-day and inter-day precisions varied in the ranges of 0.98%-5.31% and 2.16%-3.90%, respectively. Recovery of the analysis varied in the range of 83.41%-106.57%, suggesting that the values were acceptable. Additionally, vitamin B12 content and recovery in SRM 1849a were 54.10 ㎍/kg and 112.24%, respectively. Our results suggested that the analytical method, including the sample pretreatment step, was valid. This analytical method can be implemented in many laboratory-scale experiments that seek to save time and labor. Therefore, this study shows that immunoaffinity-HPLC/ultraviolet is an acceptable technique for constructing a reliable database on vitamin B12 in powdered milk containing starch as well as protein and/or fat in high amounts.

• International Journal of Computer Science & Network Security
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• 제24권5호
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• pp.217-223
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• 2024

The current study aimed to evaluate the effectiveness of using Support Vector Machine (SVM) for political affiliation classification. The system was designed to analyze the political tweets collected from Twitter and classify them as positive, negative, and neutral. The performance analysis of the SVM classifier was based on the calculation of metrics such as accuracy, precision, recall, and f1-score. The results showed that the classifier had high accuracy and f1-score, indicating its effectiveness in classifying the political tweets. The implementation of SVM in this study is based on the principle of Structural Risk Minimization (SRM), which endeavors to identify the maximum margin hyperplane between two classes of data. The results indicate that SVM can be a reliable classification approach for the analysis of political affiliations, possessing the capability to accurately categorize both linear and non-linear information using linear, polynomial or radial basis kernels. This paper provides a comprehensive overview of using SVM for political affiliation analysis and highlights the importance of using accurate classification methods in the field of political analysis.

• 분석과학
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• 제28권6호
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• pp.460-466
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• 2015

분유 내 콜레스테롤을 정량분석하기 위한 일차분석법으로 동위원소희석 질량분석법을 개발하였다. 내부표준물질로 콜레스테롤-d₄를 사용하여 분유에 첨가하였다. 분유에 지방산과 에스테르형태로 결합되어 있는 콜레스테롤을 자유 콜레스테롤로 바꾸어주기 위해 비누화과정을 수행하였다. 비누화과정은 반응온도, 반응시간, 사용한 KOH의 농도에 따라서 최적화하였으며, 그 결과로 분유시료 0.1 g에 대해 70 ℃에서 180 분 동안 8 M의 KOH 0.8 mL를 첨가하여 반응을 진행시키는 최적화조건을 확립하였다. 이와 같은 조건으로 실험을 진행하여 재현성은 0.23%, 확장불확도는 95%의 신뢰범위에서 1.9%로 추정되었다. 확립된 동위원소희석 질량분석법의 유효화를 위해 분유내에서 콜레스테롤의 인증값을 가지는 NIST SRM을 측정하였고 이 결과가 인증값과 불확도 범위내에서 일치하는 것을 확인하였다.

• 분석과학
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• 제16권5호
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• pp.391-398
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• 2003

하나로의 즉발감마선 방사화분석 장치를 이용하여 생물시료중의 붕소의 정량을 위한 기초연구를 수행하였다. 측정조건에 대한 특성조사를 위해 시료에 대한 중성자 조사 위치에서 중성자속 및 균질도를 측정하였다. 시료위치에서 열중성자 빔의 크기가 $2{\times}2cm^2$ 되도록 집속하였으며, 측정된 선속은 $1.0{\sim}6.5{\times}10^7n{\cdot}cm^{-2}{\cdot}s^{-1}$ 범위를 나타냈으며, 중심부로부터 반경 4.5 mm 이내 및 9 mm 이내에서 각각 $5.77{\pm}0.71{\times}10^7n{\cdot}cm^{-2}{\cdot}s^{-1}$, $4.68{\pm}1.64{\times}10^7n{\cdot}cm^{-2}{\cdot}s^{-1}$이었다. 따라서 양질의 균일한 조사를 위해서 시료의 크기를 10 mm 이내로 조정하였다. 검출 시스템은 컴프턴 산란에 의한 백그라운드 요인을 억제하고 분석감도를 높이기 위해 설계되었으며, 감마선 계측 시스템의 에너지 교정과 컴프턴 억제율을 조사하기 위해 NaCl 표준체를 이용하여 단일 및 컴프턴 모드로 백그라운드를 측정하였다. 또한 정확한 붕소의 측정을 위해 시료의 매질효과로서 발생하는 분광학적 Na의 472 keV 피이크에 대한 간섭효과를 결정하였으며, 세 가지 인증표준물질 (NIST SRM 1570a, 1547, 1573a)을 이용한 붕소농도 측정시험을 두 가지 모드로 실시한 후 결과를 비교하였다.

• Journal of Magnetics
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• 제21권3호
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• pp.393-398
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• 2016

This paper proposes a novel 16/10 segmented rotor switched reluctance motor (SSRM) for belt-driven starter generators (BSGs). Different from conventional SRMs, the stator of the proposed SSRM consists of two types of stator poles, i.e., exciting and auxiliary poles, and the rotor is constructed from a series of discrete segments. The topology and operation principle of this proposed SSRM are illustrated firstly, and then the design rules are listed. In addition, the finite element method (FEM) is employed to get the static and dynamic characteristics of the proposed SSRM. Finally, the simulation results are presented to show the validity of the proposed SSRM for BSGs.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.806-807
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• 2011

This paper presents a new sensorless controller used with both the classical sliding mode observer(SMO) and the rate of current change in order to a reduced torque ripple for switched reluctance motor (SRM) sensorless drives. The new sensorless scheme consists of a sliding mode observer (SMO)-based position sensorless approach for high speeds along with a low-resolution discrete the rate of current change for low speeds and standstill. The new position estimation resets between the SMO and the low-resolution of current change according to the speed sign and the position error difference between the SMO and the low-resolution rate of current change. The simulation results show the robustness of this new high performance sensorless control approach with the hybrid sensorless control topology.