• 한국수학교육학회지시리즈E:수학교육논문집
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• 제34권3호
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• pp.355-372
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• 2020

무한급수 개념은 학부의 전공 수학 교육과정의 중요한 주제이다. 여러 세기 동안 그것은 학습자에게 직관에 반대되는 장애를 제공했을 뿐만 아니라 해석학 연구의 중심적 역할을 해 왔다. 수학의 역사에서 무한급수 개념에 대한 이해가 미적분학 발달의 기초가 되었듯이 현재의 학생들에게 무한급수 개념에 대한 이해는 전공 수학을 학습하는 데 꼭 필요하다. 무한합의 개념을 가진 학생 대부분은 무한급수의 수렴 판정 같은 수학적 내용은 어려워하지 않으나 무한급수 개념을 부분합의 열을 이용해서 구성하는 것은 어려워한다. 이에 본 연구에서는 무한급수 개념을 구성하는 방법을 APOS 이론과 발생적 분해의 관점에서 부분합 스키마를 이용하여 분석하고자 한다. 질적 연구를 통해 급수 개념의 구성 방법을 점검해서 무한급수 지도 개선에 대한 유용한 교육적 시사점을 얻고자 한다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권6호
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• pp.2801-2816
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• 2016

Owing to their low scalability, weak support on big data, insufficient data collaborative analysis and inadequate situational awareness, the traditional methods fail to meet the needs of the security data analysis. This paper proposes visualization methods to fuse the multi-source security data and grasp the network situation. Firstly, data sources are classified at their collection positions, with the objects of security data taken from three different layers. Secondly, the Heatmap is adopted to show host status; the Treemap is used to visualize Netflow logs; and the radial Node-link diagram is employed to express IPS logs. Finally, the Labeled Treemap is invented to make a fusion at data-level and the Time-series features are extracted to fuse data at feature-level. The comparative analyses with the prize-winning works prove this method enjoying substantial advantages for network analysts to facilitate data feature fusion, better understand network security situation with a unified, convenient and accurate mode.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2008년도 하계학술대회 논문집
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• pp.274-276
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• 2008

This paper proposes an individual charge equalization converter using selective two current paths for series connected lithium-ion battery strings. In the proposed equalizer, a central equalization converter acting as a controllable current source is sequentially connected in parallel with individual batteries through an array of cell selection switches. A flyback converter with a modified rectifier realizes a controllable current source. A central equalization converter is shared by every battery cells through the cell selection switch, instead of a dedicated charge equalizer for each cell. With this configuration, although the proposed equalizer has one dc-dc converter, individual charge equalization can be effectively achieved for the each cell in the strings. Furthermore, since the proposed equalizer would not allocate the separated dc-dc converter to each cell, such that the implementation of great size reduction and low cost can be allowed. In this paper, an optimal power rating design guide is also employed to obtain a minimal balancing size while satisfying equalization requirements. A prototype for eight lithium-ion battery cells is optimally designed and implemented. Experimental results verify that the proposed equalization method has good cell balancing performance showing small size, and low cost.

• 대한조선학회논문집
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• 제28권2호
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• pp.77-94
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• 1991

일정속도로 항주하는 배에 치하여 생성되는 파를 유한차분법을 이용하여 수치적으로 시뮬레이션 하였다. 지배방정식으로는 3차원 운동량방정식(Euler Eq.)과 연속방정식을 사용하였으며, 직교 좌표 계상에서의 수치계산은 FTCS(forward time/central space)로 차분화하고 시간전진 방법(time marching scheme)으로 수행하였다. 좌표계로 staggered variable mesh system을 채용하여 기존의 계산조직을 개선하므로써, 유체 유동의 변화가 심한 선체주위에 계산 정도를 높이기 위하여 cell을 집중시켰다. 개선된 전산프로그램을 이용하여 Wigley, Series 60($C_{b}$=0.6), 그리고 MS416B 산적화물선 선형등을 대상으로 수치계산을 수행하였으며, 그 결과들을 실험값과 비교하였다.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2010년도 춘계학술대회
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• pp.540-543
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• 2010

군용 SBC에 주로 사용되는 중앙 처리 장치(Central Processing Unit)는 주로 Power PC의 계열이며 Freescale사의 G4 계열인 74xx 프로세서가 주로 사용된다. 이러한 CPU인 7447A는 System Controller를 통하여 SBC 내의 주 기억 장치와 통신을 한다. 본 논문에서는 위와 같은 SBC의 구조에서 System Controller와 DDR 메모리 소자 간 I/F를 구현함에 있어 PCB적층 구조, 소자들의 Layout, 임피던스매칭과 Rugged 환경 Level에서 적용 되는 군 환경에서 동작 가능한 DDR 메모리를 모듈로 설계하여 구현하였다. 또한, 군용환경에 적용하기위한 SBC의 형상은 주로 6U, 3U의 표준 형태로 설계되어져야 한다.

• Journal of Yeungnam Medical Science
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• 제40권2호
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• pp.207-211
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• 2023

Fat embolism syndrome is a rare but alarming, life-threatening clinical condition attributed to fat emboli entering the circulation. It usually occurs as a complication of long-bone fractures and joint reconstruction surgery. Neurological manifestations usually occur 12 to 72 hours after the initial insult. These neurological complications include cerebral infarction, spinal cord ischemia, hemorrhagic stroke, seizures, and coma. Other features include an acute confusional state, autonomic dysfunction, and retinal ischemia. In this case series, we describe three patients with fat embolism syndrome who presented with atypical symptoms and signs and with unusual neuroimaging findings. Cerebral fat embolism may occur without any respiratory or dermatological signs. In these cases, diagnosis was established after excluding other differential diagnoses. Neuroimaging using brain magnetic resonance imaging is of paramount importance in establishing a diagnosis. Aggressive hemodynamic and respiratory support from the beginning and consideration of orthopedic surgical intervention within the first 24 hours after trauma are critical to decreased morbidity and mortality.

• 한국연초학회지
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• 제26권2호
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• pp.126-134
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• 2004

Tobacco dust samples were collected for two times in primary and secondary process at 4 cigarette manufacturing factories(Shintanzin, Youngju, Wonju, Kwangju) and analyzed to evaluate usage as a raw material in production of reconstituted tobacco. The chemical constituents and HWS of tobacco dust were analyzed. Tobacco dust samples were partitioned by particle size using a series of screens ranging from 20 to 200 mesh. The amount of material retained in each fraction was quantified and sand content was also determined. Appreciable average amounts$(40-65\%)$ material at 4 locations were found to be larger than 60 mesh. Although the amount of material in each fraction increased to a maximum at 100 mesh and then decreased, the $\%$ sand continually increased with decreasing particle size. The chemical constituents and HWS content of tobacco dust have similar values in secondary process of 4 cigarette manufacturing factories but the those of primary process have different values according to the site of occurrence and manufacturing factories.

• Bulletin of the Korean Chemical Society
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• 제34권3호
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• pp.863-867
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• 2013

A series of azo disperse dyes having dicyanovinyl groups was synthesized by the Knoevenagel condensation with malononitrile from carbonyl substituted phenylazo disperse dyes which were prepared by conventional diazo coupling reaction of aniline derivatives as diazo components. A variety of coupling components such as anilines, an indole and a pyridone were used. The azo disperse dyes were evaluated for their spectral properties and dyeing assessment on the polyester fabrics. The azo disperse dyes containing dicyanovinyl groups showed bathochromic shifts and darker colors due to increased electron withdrawing strength in their azo components and extended conjugation by dicyanovinyl groups than their parent carbonyl substituted azo dyes. The dyes containing 2-acetylamino-5-methoxy substituent in the coupling component exhibited higher wavelength of maximum absorbance (${\lambda}_{max}$) and significant negative solvatochromism than those of other dyes due to intramolecular hydrogen bonding.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 The 6th International Symposium of East Asian Resources Recycling Technology
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• pp.159-164
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• 2001

A novel fluidized-bed reactor was designed and installed for bioleaching in a semi-continuous way, by which a process for bioleaching-cyanidation of Guangxi Jinya refractory gold arsenical concentrate was studied. An arsenic extraction rate reaches 82.5% after 4-day batch biooxidation of the concentrate under the optimized condition of pH 2.0, ftrric ion concentration 6.5g/L and pulp concentration 10%. And leaching rate of gold in the following gold cyanidation is over 90%. The parameters of three series fluid-bed reactors exhibit stability during the semi-continuous bioleaching of the concentrate. Arsenic in the concentrate can be got rid of 91% after 6-day leaching. Even after 4 days, 82% of arsenic extraction rate was still obtained. The recovery rates of gold are 92% and 87.5% respectively in cyaniding the above bioleached residues. The results will provide a base for further commercial production of gold development.

• Journal of Electrical Engineering and Technology
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• 제10권3호
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• pp.1058-1065
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• 2015

This paper present a current predicting control method for PMSM (permanent magnet synchronous motor) to improve the tracking performance of stator current, which regards the current vector as the control target. Solving the model state equation in the static frame (α-β frame), the dynamic change of current vector will be gained as three independent terms. These change terms, which contain the prediction of current vector, are discretized and simplified by Taylor series expansion and used to get the voltage vector as the predictive control quantity. SVPWM will transform the control voltage to the switching signal of inverter, which is newly deduced for the current vector. Simulation and experiment results are given to testy and verify the performance of this method.