• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.22 no.12
• /
• pp.1078-1085
• /
• 2011

In this paper, we analyze the relationship between energy per bit and the data rate with the variation of the system bandwidth. A existing power model is mathematical model to express power consumption of each device. In this paper, we have to investigate the system level energy model for the RF front-end of a wireless transceiver. Also, the effects of the signal bandwidth, PAR, date rate, modulation level, transmission distance, specific attenuation of frequency band, and the signal center frequency on the RF front-end energy consumption and system capacity are considered. Eventually, we analyze the relationship between energy per bit and the data rate with the variation of the system bandwidth so that we simulate the minimum energy per bit in the several Gbps data rate using Shannon capacity theory.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.17 no.3
• /
• pp.341-351
• /
• 2015

When rainfall occurred on road tunnel, that is likely to have influence upon ventilation force in the tunnels but the tunnels ventilation system did not consider factors of rainfall. Thus, this study investigated effects of rainfall upon ventilation force in the tunnels at no rainfall and changing of rainfall by 3 dimensional numerical method. Flow rate into road tunnels decreased as many as 52.34% at rainfall of 150 mm/hr, and pressure drop of road tunnel between entrance and exit decreased as many as 22.22%, so that rainfall had influence upon ventilation force in the tunnel. The number of necessary jet fan in road tunnels is 12 at no rainfall but, when rainfall of 80 mm/hr on road tunnels, the number of necessary jet fan in road tunnels is 16, when rainfall of 150 mm/hr on road tunnels, the number of necessary jet fan in road tunnels is 17. So, factor of rainfall should be considered at estimation of ventilation system of road tunnel.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.40 no.10
• /
• pp.45-51
• /
• 2003

In this paper, a scan-based low power BIST (Built-In Self-Test) architecture is proposed. The proposed architecture is based on STUMPS, which uses a LFSR (Linear Feedback Shift Register) as the test generator, a MISR(Multiple Input Shift Register) as the reponse compactor, and SRL(Shift Register Latch) channels as multiple scan paths. In the proposed BIST a degenerate MISR structure is used for every SRL channel; this offers reduced area overheads and has less impact on performance than the STUMPS techniques. The proposed BIST is designed to support both test-per-clock and test-per-scan techniques, and in test-per-scan the total power consumption of the circuit can be reduced dramatically by suppressing the effects of scan data on the circuits. Results of the experiments on ISCAS 89 benchmark circuits show that this architecture is also suitable for detecting path delay faults, when the hamming distance of the data in the SRL channel is considered.

• Journal of Educational Research in Mathematics
• /
• v.25 no.3
• /
• pp.407-429
• /
• 2015

This study aims to find the elementary mathematics teachers' satisfaction, availability, and needs, based on the mathematics teaching models in current mathematics curriculum. The satisfaction on current mathematics teaching models is about 80%, but the frequency of usage of the models is a bit low because the models are used once a unit or a semester. Among other subjects, the teachers prefer the teaching models of social studies or science, because the models are convenient in applying models to their teaching. We proposed a few ideas to enhance the availability of mathematics teaching models including the consideration on a variety of content areas of mathematics, students' differences of their mathematics levels, and the teaching and learning methods in mathematics curriculum.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 1997.04a
• /
• pp.191-201
• /
• 1997

혼합형 고체추진제에는 연소속도를 증가시키는 촉매로서 철,구리,크롬등 전이금속 $화합물^1$ 이 사용되고 있다. 현재 당공장에서 양산되는 개량형 추진기관의 추진제에 철화합물인 $Fe_2$ $O_3$ 가 사용되는데 그동안 $Fe_2$ $O_3$ 를 공급해온 미국 Columbian chemical co.에서 생산을 중단함에 따라 새로운 수급이 필요하게 되었다. 이에 이원료의 안정적인 공급을 위해 국산 $Fe_2$ $O_3$ 로 대체 개발하기 위해 국산 원료의 시장조사, 샘플 입수, 그리고 원료분석을 실시하였지만 당공장에서 사용해온 $Fe_2$ $O_3$ 의 원료규격중 순도, 산도(PH값), 입도등 중요항목을 만족할만한 국산 원료는 발견하지 못했다. 하지만 국내 제조업체중 제조능력 및 시설을 고려하여 일신종합화학(인천 소재)을 선정한 다음 제조 공정의 개선을 통하여 당공장 사용 원료을 만족하는 원료를 생산할 수 있었고, 개향형 추진 기관의 추진제에 적용하여 추진제 공정성, 물성, 그리고 가장 중요한 연소특성을 만족하는 국산 $Fe_2$ $O_3$ 를 개발에 성공하여 양산에 적용하고 있다.

• Proceedings of the Korean Radioactive Waste Society Conference
• /
• 2006.11a
• /
• pp.225-226
• /
• 2006

본 논문에서는 PWR 사용후핵연료의 처분용기를 원가대상으로 단위당 제조원가를 추정하였다. 추정결과, 처분용기의 내부는 구상흑연주철로 외부는 순동판으로 후판 제작하였을 경우, KDC-1 처분용기의 단위당 제조원가는 약 2억 3천만원으로 추정되었다. 또한 외부용기를 순동 주물로 제조하였을 경우는 단위당 제조원가가 약 2억 1천만원으로 추정되었다. 그리고 외부용기를 후판제작 할 경우, 총 제조원가 대비 각 제조원가의 2대 요소별로 비율을 살펴보면, 직접재료비는 38%, 직접 노무비 50%, 제조간접비 12%로 추정되었다. 따라서 한국형처분장 개념설계에서 36,000tU을 처분하는데 소요되는 처분용기 14,210개중 PWR 처분용기 11,375개를 고려하였을 경우, 처분용기 총 원가는 사용후핵연료 처분 총 원가의 주요한 원가동인임을 확인하였다.

• The Korean Journal of Mycology
• /
• v.19 no.4
• /
• pp.253-257
• /
• 1991

Cellular carbohydrates were hydrolysed and analyzed in the strains of Leucosporidium scottii and its related species of basidiomycetous yeasts by HPLC methods without any derivatization. Xylose was detected from the hydrolyses of the cellular carbohydrates of L. lari-marini, but not from those of three strains of L. antarcticum, L. fellii, and Rhodosporidium fluviales. not also from those of six strains of L. scottii contrary to other data reported. L. antarcticum and L. lari-marini were considered to be placed on the different genus of Cystofilobasidium or Mrakia, as based on the numerical analyses.

• Aerospace Engineering and Technology
• /
• v.10 no.1
• /
• pp.193-200
• /
• 2011

The external disturbance torque acting on a low earth orbit spacecraft was analyzed. For the Earth pointing attitude, the maximum torque to the spacecraft is about $8.3{\times}10^{-4}$ Nms and the momentum accumulated for an orbit is about 1.4 Nms and for the Sun pointing attitude, the maximum torque to the spacecraft is about $1.6{\times}10^{-3}$ Nms and the momentum is accumulated about 3.0 Nms in the spacecraft body reference frame. The analysis results confirm that the size of magnetic torquer selected previously for the satellite is sufficient to manage the accumulated momentum by considering the dumping capacity for an orbit.

• Proceedings of the Korea Multimedia Society Conference
• /
• 2002.05d
• /
• pp.685-689
• /
• 2002

Ad hoc 네트워크에서 클러스터 구성은 채널의 효율적 사용, 제어메시지의 교환부하 감소, 이동성 관리 용이, 그리고 QoS라우팅 지원등의 이점을 지닌다. 이런 이유로 인해 클러스터 구조는 자주 변경되지 않아야 하고, 노드의 이동성을 반영하여 클러스터를 구성하여야 한다. 그러나 기존의 클러스터 구성에 관한 연구에서는 노드의 이동성을 고려하지 않고 있으며, 이동성을 고려하는 경우에는 이동속도만을 고려하여 클러스터를 구성함으로써 클러스터의 잦은 변경을 유발한다. 이에 본 논문은 단위 시간당 클러스터 변경 횟수, 현재 클러스터에 체류한시간, 그리고 평균적으로 클러스터에 체류한 시간을 이용하여 이동성을 고려한다. 또한 라우팅 효율성을 위해, 차수도 고려하여 클러스터를 구성한다. 그리고 클러스터 구성절차의 적절한 수행횟수를 보장하기 위하여 LCC[4]의 수정된 클러스터 구조 유지전략을 제공한다.

• Journal of the Korean Society for information Management
• /
• v.29 no.1
• /
• pp.115-134
• /
• 2012

The author co-citation analysis is generally based on the frequency of the first author because most citation databases include only the first author in the bibliographic information. In this sense, the purpose of this study is to provide a better knowledge structure by utilizing the multiple authorship of author co-citation analysis. To achieve the purpose of this study, four different data sets are prepared: (1) counting the first author, (2) counting all the author without limiting the total frequency, (3) counting all the author with limiting the total frequency, and (4) counting adjusted frequencies based on the order of author subscription. The findings of this study show that there are clear differences between the knowledge structure counting all the author and the one counting only the first author. In addition, depending on the different methods, there are subtle changes of cluster members for authors.