• Proceedings of the KIPE Conference
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• 전력전자학회 2018년도 전력전자학술대회
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• pp.207-209
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• 2018

본 논문은 고효율 및 고전력밀도 3-레벨 PFC(Power Factor Correction) 컨버터를 제안한다. 기존 PFC의 고 전력밀도를 위한 스위칭 주파수 상승은 스위칭 특성이 우수한 소자를 적용하거나, 별도의 스너버 회로가 요구되므로 설계가 복잡하며 고전력밀도 달성에 한계가 있다. 제안 PFC 컨버터는 3-레벨 방식을 적용하여 각 스위칭 소자의 전압 스트레스를 절반으로 감소시켰으며, 스위치 손실 저감을 통한 고속 스위칭 동작으로 리액티브 소자의 고밀도화를 달성하였다. 또한, 기존의 3-레벨방식은 디지털 제어를 통해 스위칭 소자의 전압 평형이 이루어졌지만, 본 논문에서는 아날로그 IC에 전압 평형을 위한 RC Delay 회로와 소수의 SMD(Surface-mount devices) 소자만을 이용하여 별도의 제어회로 없이 전압 평형이 가능하므로 고 전력밀도 달성에 유리하다. 제안회로의 타당성을 검증하기 위해 CRM(Critical conduction mode) PFC 컨버터를 기반으로 250W급 시작품 제작을 통한 실험 결과를 제시한다.

• Proceedings of the Korea Information Processing Society Conference
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• 한국정보처리학회 2015년도 추계학술발표대회
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• pp.987-989
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• 2015

최근 청년실업으로 인해 각 대학들은 학교별 특성에 맞는 취업프로그램을 실시하고 있다. 현재 순천향대 취업 담당자들은 취업프로그램을 진행하며 면담 및 학생정보를 수기로 작성 하고 있어 불편한 점이 많다. 본 논문에서는 기존의 CRM 고객관리시스템을 응용하여 고객이 아닌 학생의 상담내역을 기반으로 취업의 방향과 전략을 세우는 학생 취업 관리 시스템을 구현하였다. 본 논문에서 구현한 시스템은 Spring 프레임워크, MVC 패턴을 활용하여 역할의 분명한 분리를 수행하고, 이를 통해 보다 효율적인 웹을 구현할 수 있도록 하였다.

• Analytical Science and Technology
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• 제18권1호
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• pp.74-84
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• 2005

Understandings of adsorption characteristic of interface are very important in several advanced materials processes, related to NT and BT technology. Volumetric gas adsorption method, suitable for absolute measurements, is regarded as the standardized measurement technique for specific surface area. In order to verify the reliability of commercial equipments, certified reference materials (called CRM) of specific surface area are developed and evaluated its uncertainty factors by standard equipment which has traceability to SI units. Specific surface areas of developed materials are $10.72{\pm}0.46m^2g^{-1}$ for silicon nitride powders and $149.50{\pm}3.44m^2g^{-1}$ for alumina. These disseminations of CRMs would result in improved reliability chains in industrial processes, and lead eventually to contribution to productivity improvement, quality management, safety evaluation, and possibly to new material development.

• Journal of the Korean Data and Information Science Society
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• 제24권2호
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• pp.245-255
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• 2013

The object of study is to propose a method for grouping R, F, and M in RFM model. Our model uses 6 levels using standard normal distribution. First level is upper 2.5% and second level next 13.5%, third level next 34%, fourth level next 34%, fifth level next 13.5%, sixth level next 2.5%. Values are symmetric and limits are clear. We compare proposed model with traditional 5 level model and 10 level model using NDSL data of KISTI. Proposed model divides most clearly the distribution of the RFM function for all cases of weights, because it uses the distribution of customers. Comparison studies of our model with grouping using cluster analysis and studies on weights of RFM model are needed.

• Analytical Science and Technology
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• 제15권5호
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• pp.417-426
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• 2002

Inductively Coupled Plasma Dynamic Reaction Cell Quadrupole Mass Spectrometry (ICP-DRC-QMS) was characterized for the detection of the six naturally occurring calcium isotopes. The effect of the operating conditions of the DRC system was studied to get the best signal-to-noise ratio. This experiment shows that the potentially interfering ions such as $Ar^+$, ${CO_2}^+$, ${NO_2}^+$, $CNO^+$ at the calcium masses m/z 40, 42, 43, 44 and 48 were removed by flowing $NH_3$ gas at the rate of 0.7 mL/min $NH_3$ as reactive cell gas in the DRC with a RPq value (rejection parameter) of 0.6. The limits of detection for $^{40}Ca$, $^{42}Ca$, $^{43}Ca$, $^{44}Ca$, and $^{48}Ca$ were 1, 29, 169, 34, and 15 pg/mL, respectively. This method was applied to the determination of calcium in synthetic food digest samples (CCQM-P13) provided by LGC for international comparison. The isotope dilution method was used for the determination of calcium in the samples. The uncertainty evaluation was performed according to the ISO/GUM and EURACHEM guidelines. The determined mean concentration and its expanded uncertainty of calcium was ($66.4{\pm}1.2$) mg/kg. In order to assess our method, two reference samples, Riverine Water reference sample (NRCC SLRS-3) and Trace Elements in Water reference sample (NIST SRM 1643d), were analyzed.