• 대한수학교육학회지:학교수학
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• 제12권4호
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• pp.667-686
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• 2010

2009 개정 교육과정 총론에 따라 수학과 교육과정 개정 시안 연구가 진행 중이다. 수학과 교육과정 개정 연구팀이 교육과정 체제의 측면에서 고려하고 있는 두 가지 중요한 사항은 '학년군의 도입'과 '수학적 과정의 신설'이다. 본 고는 학년군과 수학적 과정 도입의 타당성을 검토하기 위해 이 두 가지 측면을 중심으로 외국의 수학과 교육과정을 비교 분석하였다. 그 결과 학년군의 도입은 실효성을 갖기 어렵기 때문에 재고의 여지가 있고, 수학적 과정의 신설은 수학 교과서 집필과 수업의 방향성을 제시한다는 측면에서 긍정적인 측면을 갖는 것으로 평가하였다.

• KIEE International Transactions on Electrophysics and Applications
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• 제4C권4호
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• pp.165-169
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• 2004

This paper reports a miniaturized conductor-backed CPW (CBCPW) bandpass filter based on a thin film polyimide layer coated on CMOS-grade silicon. With a 20 ${\mu}{\textrm}{m}$-thick polyimide interface layer and back metallization on the CMOS-grade silicon, the interaction of electromagnetic fields with the lossy silicon substrate has been isolated, and as a result a low-loss and low-dispersive CBCPW line has been obtained. Measured attenuation constant at 20 GHz is below 1.2 ㏈/cm, which is compatible with the CPW on GaAs. In addition, by using the proposed CBCPW geometry, miniaturized BPF for Ku band application is designed and its measured frequency response shows excellent agreement with the predicted value with validating the performances of the proposed CBCPW geometry for RFIC interconnects and filter applications.

• 전기의세계
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• 제25권6호
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• pp.69-73
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• 1976

Thd idle channel noise on FDM-microwave communication system is increasing because of the up-grade to wide-band loading. The thermal noise on receiver of microwave radio is measured according to their channel slot frequencies, low, meddle and high slots on the base band, from 60 channels to 960 channels. And suggested a consideration for system engineering, to reduce the thermal noise from radio microwave receivers, so as to improve signal to noise ratio.

• 디지털산업정보학회논문지
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• 제11권3호
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• pp.91-98
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• 2015

There is a new evolution in technological advancement taking place called the Internet of Things (IoT), The IoT enables physical world objects in our surrounding to be connected to the Internet. ISM (Industrial Scientific Medical) band that is 2.4GHz band authorized free of charge is being widely used for smart devices. Accordingly studies have been continuously conducted on the possibility of coexistence among nodes using ISM band. In particular, the interference of IEEE 802.11b based Wi-Fi devices using overlapping channel during communication among IEEE 802.15.4 based wireless sensor nodes suitable for low-power, low-speed communication using ISM band. Because serious network performance deterioration of wireless sensor networks. In this paper, we will propose an algorithm that identifies the possibility of using more accurate channels by mixing utilization of interference signal and RSSI (Received Signal Strength Indicator) Min/Max/Activity of Interference signal by wireless sensor nodes. In addition, it will verify our algorithm by using OPNET Network verification simulator.

• 항공우주시스템공학회지
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• 제4권1호
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• pp.27-31
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• 2010

The scope of this paper is to analyze the safety aspects of the Ka-band payload system which are associated with testing, transportation, integration, handling and storage. According to ESA philosophy and the ECSS-Q-40A "Space Product Assurance - Safety", safety hazard analysis of Ka band payload was performed. In this paper, it is indicated the requirements to be satisfied for eliminating, reducing, or controlling the hazards and by showing how they have been implemented in the COMS design. And it shows the safety hazard analysis result which has performed the analysis according to ESA document and also shows the potential hazard cause, potential effects, hazard grade and criteria resolution of Ka band COPS.

• 한국수정란이식학회지
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• 제23권4호
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• pp.291-298
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• 2008

We separately cultured follicular oocytes collected from individual ovaries of slaughtered Korean native cows and examined both the embryonic development rate and pregnancy rate after embryo transplantation according to the meat yield and quality grades of the source beef carcass. Oocytes from meat yield grade B cows exhibited a higher fertilization rate and embryonic developmental rate to the eight-cell stage than oocytes from grade A or C animals (p<0.05), but there was no significant difference in rate of development to the blastocyst stage among meat yield grades A, Band C. The oocyte cleavage rate and development rate to the eight-cell stage from meat quality grade 3 cattle was higher than grades 1++, 1+, 1 and 2 (p<0.05). Embryos derived from grade animals displayed a development rate to the blastocyst stage of 19.4%, which was also higher than all other meat quality grades (p<0.05). Transplantation of in vitro-cultured oocytes from meat yield grade A ovaries led to a higher pregnancy rate (64.2%) than in vitro-cultured oocytes from meat yield grade B ovaries (56.5%), but there was no significant difference between the two groups in pregnancy or abortion rates. In conclusion, embryonic development rate and pregnancy rate has a close relation to meat quality grades of the source beef carcass, this results is to give information for the Korean native cows improvement of breed.

• Nuclear Engineering and Technology
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• 제55권5호
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• pp.1519-1526
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• 2023

For the first time Aluminium-BariumeZinc oxide nanocomposite (ZABONC) was synthesized by solution combustion method where calcination was carried out at low temperatures (600℃) to study the electromagnetic (EM) (X/γ) radiation shielding properties. Further for characterization purpose standard techniques like PXRD, SEM, UV-VISIBLE, FTIR were used to find phase purity, functional groups, surface morphology, and to do structural analysis and energy band gap determination. The PXRD pattern shows (hkl) planes corresponding to spinel cubic phase of ZnAl₂O4, cubic Ba(NO₃)₂, α and γ phase of Al₂O₃ which clearly confirms the formation of complex nano composite. From SEM histogram mean size of nano particles was calculated and is in the order of 17 nm. Wood and Tauc's relation direct energy band gap calculation gives energy gap of 2.9 eV. In addition, EM (X/γ) shielding properties were measured and compared with the theoretical ones using standard procedures (NaI (Tl) detector and multi channel analyzer MCA). For energy above 356 keV the measured shielding parameters agree well with the theory, while below this value slight deviation is observed, due to the influence of atomic/crystallite size of the ZABONC. Hence synthesized ZABONC can be used as a shielding material in EM (X/γ) radiation shielding.

• 한국군사과학기술학회지
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• 제26권3호
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• pp.227-233
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• 2023

In this paper, to substitute the existing TWTA(Travailing Wave Tube Amplifier) component in small radar system, we developed the Ku band SSPA(Solid-State Power Amplifier) based on the fabrication of power MMIC (Monolithic Microwave Integrated Circuit) chips. For the development of the 500 W SSPA, the 40 W-grade power MMIC was designed by ADS(Advanced Design System) at Keysight company with UMS GH015 library, and was processed by UMS foundry service. And 70 W main power modules were achieved the 2-way T-junction combiner method by using the 40 W-grade power MMICs. Finally, the 500 W SSPA was fabricated by the wave guide type power divider between the drive power amplifier and power modules, and power combiner with same type between power modules and output port. The electrical properties of this SSPA had 504 W output power, -58.11 dBc spurious, 1.74 °/us phase variation, and -143 dBm/Hz noise level.

• 한국수학교육학회지시리즈A:수학교육
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• 제38권1호
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• pp.87-94
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• 1999

A multimedia CD title is developed for learning simple closed curve and Mobius band which are one of mathematics contents in the first grade of middle school. This title visualizes various figures through graphics and animations so that students can easily understand the relevant concepts and learn them with fun. It is shown that 88.6% of 30 sampled teachers are positive for the title and that 86.7% want to use it as a teaching tool in their classes.

• 대한수학교육학회지:학교수학
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• 제14권4호
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• pp.531-552
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• 2012

2009 개정 교육과정에 따른 수학과 교육과정의 적용은 초 중학교의 경우 2013년부터이며 연차적으로 확대 적용될 전망이다. 새 교육과정의 적용이 시작되는 현 시점에서 '2009 개정 교육과정 총론'과 '2009 개정 교육과정에 따른 수학과 교육과정'이 유기적으로 연계하여 적용될 수 있도록 다각적인 검토를 통해 수학과 교육과정을 적용하는 데 발생하는 어려움, 즉 쟁점을 신중히 탐색하고 이에 대한 해결 방안을 마련할 필요가 있다. 수학과 교육과정 적용 시, 쟁점이 되는 항목은 2009 개정 교육과정 총론의 변화에 따른 것으로, 이는 학년군, 수준별 수업, 기준 수업시수의 20% 이내 증감 운영으로 구체화 할 수 있다. 본고에서는 이 세 가지의 쟁점 사항을 중심으로 수학과 교육과정을 적용하는데 있어서의 효율적인 방안을 모색하고자 하였다.