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Analysis of Free Vibration and Damping Characteristics of a Composite Plate by Using Modified 3-Dimensional 16-Node Elements (수정된 3차원 16절점 요소에 의한 복합재 판의 자유진동 및 감쇠특성 해석)

  • 윤태혁;김상엽;권영두
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.19 no.4
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    • pp.990-1004
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    • 1995
  • A modified 16-node element for composite plate has been proposed and compared with the 20-node element to check the validity of it. The fields of numerical inspection include mode analysis and specific damping analysis. By symetrizing the conventional unsymmetric damping matrix in the analysis of specific damping capacity, we could compute the specific damping capacity and make a program, effectively. In addition, we could predict the errors caused by reduction of integration order in thickness direction depending upon the number of layers.

Physicochemical and Microbial Properties of Korean Traditional Rice Wine, Makgeolli, Supplemented with Black Garlic Extracts during Fermentation

  • Jeong, Yoon-Hwa
    • Preventive Nutrition and Food Science
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    • v.16 no.2
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    • pp.142-149
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    • 2011
  • The purpose of this study was to elucidate the physicochemical and microbiological properties of Korean traditional rice wine, Makgeolli, supplemented with black garlic extract during fermentation. Black garlic extract was diluted with distilled water to produce 0.5% and 1.0% black garlic solutions. Those solutions were then used to make rice solutions which included 2 kg rice, 40 g Nuruk (a fermentation starter), and 14 g yeast. After being mixed, the rice solutions were fermented for 7 days in a water bath at $28^{\circ}C$. The alcohol contents of the control, 0.5% and 1.0% black garlic Makgeolli were 16.9, 16.0, and 16.2%, respectively. Total acidity, total soluble solids, and color increased throughout the fermentation process. There was an increase of microorganisms throughout the fermentation period in all the samples. Glucose was the highest free sugar, and succinic acid was the highest organic acid detected in all the samples. Thirty nine volatile compounds were detected in black garlic Makgeolli.

Development of C Compiler using GCC generator (GCC 생성기를 이용한 C 컴파일러 개발)

  • Jeong, Sam-Jin
    • Proceedings of the KAIS Fall Conference
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    • 2010.11a
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    • pp.216-220
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    • 2010
  • 본 연구는 앞으로 개발될, 혹은 현재 개발이 진행중인 16 비트 CPU를 위한 C 컴파일러를 개발하고자 한다. 본 연구는 다양하고 특별한 용도의 새로운 CPU를 위한 새로운 C 컴파일러들을 보다 쉽게 개발할 수 있게 한다. 공개 소프트웨어인 GNU C 컴파일러 생성기를 사용하여 새로운 CPU의 기능들을 명세하고, 기계 의존 원시 파일들을 수정함으로서 새로운 컴파일러를 개발할 수 있다. 개발된 컴파일러는 16 비트 CPU가 지원하는 16 비트 산술 연산 뿐만 아니라, 16 비트 CPU가 지원하지 않는 16 비트 산술 연산, 32 비트 Data Movement 연산, 32 비트 산술 연산, 32 비트 floating point 연산까지 가능하다. 그러나, 배열, 포인터, 구조체 등과 같은 고급 기능들을 지원하기 위해서는 더 많은 연구가 필요하다.

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Characteristics of Insulation Aging in 4.16kV Motor Stator Windings (4.16kV 전동기 고정자 권선의 절연열화 특성)

  • Kim, Hee-Dong;Kong, Tae-Sik
    • Proceedings of the KIEE Conference
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    • 2009.07a
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    • pp.1381_1382
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    • 2009
  • Nondestructive tests were performed on two 4.16kV motors. Epoxy-mica coupler(80pF) was connected to 4.16 kV motor stator windings. The voltage applied to the stator windings was 2.4 kV, 3.0kV, 3.5kV and 4.16kV, respectively. Digital partial discharge detector(PDD) and turbine generator analyzer(TGA) were used to measure partial discharge(PD) activity. TGA summarizes each plot with two quantities such as the normalized quantity number(NQN) and the peak PD magnitude(Qm). The PD levels in pC were measured with PDD. PD patterns of stator windings were indicated the internal discharge. PD patterns are consistent with the result of measurement using PDD and TGA.

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Competitive Solvent Extractions of Alkaline Earth Metal Cations by Crown Ether Phosphonic Acid Monoethyl Esters (크라운에테르 포스포닉산 모노에틸 에스테르에 의한 알칼리 토금속 양이온의 경쟁 용매추출)

  • Chung, Yeong-Jin
    • Journal of the Korean Applied Science and Technology
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    • v.22 no.1
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    • pp.9-14
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    • 2005
  • Competitive solvent extraction of alkaline earth metal cations from water into organic solvent containing the carboxylic acid crown ether and analogous crown ether phosphonic acid monoethyl esters were investigated. sym-(n-Decyldibenzo)-16-crown-5xyacetic acid $\underline{1}$ and monoethyl sym-(n-decyldibenzo)-16-crown-5-oxymethylphosphonic acid $\underline{3}$ are structurally identical except for the ionizable groups. Both of them provide similar extraction behavior in terms of efficiency and selectivity, but monoethyl sym-(n-decyldibenzo)-16-crown-5-oxymethylphosphonic acid $\underline{3}$ showed higher alkaline earth metals loadings at acidic or neutral media. Monoethylsym-(n-octyldibenzo)-16-rown-5-oxymethylphosphonic acid $\underline{2}$ showed better selectivity and alkaline earth metals loading than did the analogous sym-(n-octyldibenzo)-16-crown-5-oxymethyldiphosphonic acid $\underline{6}$.

Characterization of Cytophaga-Flavobacteria Community Structure in the Bering Sea by Cluster-specific 16S rRNA Gene Amplification Analysis

  • Chen, Xihan;Zeng, Yonghui;Jiao, Nianzhi
    • Journal of Microbiology and Biotechnology
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    • v.18 no.2
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    • pp.194-198
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    • 2008
  • A newly designed Cytophaga-Flavobacteria-specific 16S rRNA gene primer pair was employed to investigate the CF community structure in the Bering Sea, revealing a previously unknown and unexpected high CF diversity in this high latitude cold sea. In total, 56 clones were sequenced and 50 unique CF 16 rRNA gene fragments were obtained, clustering into 16 CF subgroups, including nine cosmopolitan subgroups, five psychrophilic subgroups, and two putatively autochthonous subgroups. The majority of sequences (82%) were closely related to uncultured CF species and could not be classified into known CF genera, indicating the presence of a large number of so-far uncultivated CF species in the Bering Sea.

QoS Packet-Scheduling Scheme for VoIP Services in IEEE 802.16e Systems

  • Jang, Jae-Shin;Lee, Jong-Hyup;Cheong, Seung-Kook;Kim, Young-Sun
    • Journal of Communications and Networks
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    • v.11 no.1
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    • pp.36-41
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    • 2009
  • The IEEE 802.16 wireless metropolitan area network (WMAN) standard is designed to correct expensive communication costs in CDMA-based mobile communication systems and limited coverage problems in wireless LAN systems. Thus, the IEEE 802.16e standard can provide mobile high-speed packet access between mobile stations and the Internet service provider through the base station with cheap communication fees. To efficiently accommodate voice over IP (VoIP) services in IEEE 802.16 systems, an uplink quality of service packet-scheduling scheme is proposed, and its performance is evaluated with an NS-2 network simulator in this paper. Numerical results show that this proposed scheme can increase the system capacity by 100% more than in the unsolicited rand service (UGS) scheme and 30% more than the extended real-time polling service (ertPS) scheme, respectively.

An efficient Uplink Scheduling Scheme and Performance Analysis of MAC Layer fer VoIP Service in IEEE 802.16j System (IEEE802.16j System의 VoIP 서비스를 위한 MAC Layer에서 효율적인 업링크 스케줄링 기법 및 성능 분석에 관한 연구)

  • Lee, Seung-Do;Lee, Tae-Jin
    • Proceedings of the Korean Information Science Society Conference
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    • 2007.10d
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    • pp.602-607
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    • 2007
  • 최근 4G 이동통신 시스템의 진화를 위한 단계로 기존의 이동통신 시스템을 유지하면서 효율 극대화를 통한 비용 절약 측면과 고 주파수 대역을 이용한 셀 간격의 협소화로 인해 나타나는 문제점에 대한 대안으로 커버리지 확대와 데이터 처리율 향상을 위한 IEEE 802.16j 표준화 작업이 진행 중에 있다. 향후 VoIP 서비스를 위한 업링크 스케줄링 기법으로 몇 가지가 IEEE 802.16j에 제시되어 있으나, 본 논문에서는 보이스 트래픽 특성 및 수학적 모델링을 통하여 기존 방법들보다 더 효율적인 대역 이용을 통해 같은 대역폭 대비 성능과 용량 면에서 개선된 스케줄링 기법인 eertPS를 제시하여 IEEE 802.16j Multi-Hop 환경하에서도 대역 효율적인 VoIP 서비스를 이용할 수 있도록 한다.

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The Effects of ARQ Timers on TCP Performance in IEEE 802.16 Systems (IEEE 802.16 시스템에서 ARQ 타이머가 TCP 성능에 미치는 영향)

  • Lee, Ji-Hoon;Park, So-Young;Park, Chul-Hyun;Kwon, Tae-Kyung;Choi, Yang-Hee
    • Proceedings of the Korean Information Science Society Conference
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    • 2008.06d
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    • pp.165-169
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    • 2008
  • 본 논문에서는 IEEE 802.16 시스템에서 ARQ(Automatic Repeat reQuest)의 동작이 TCP 성능에 끼치는 영향을 분석한다. IEEE 802.16 표준에서는 MAC 계층에서 패킷 전송의 성공 혹은 실패를 확인하여, 실패 시 패킷을 재전송하는 ARQ 기법을 포함하고 있다. 이러한 무선 링크상의 재전송은 TCP와 맞물려 동작할 때, 적절한 ARQ 재전송 타임아웃(timeout)이 보장되지 않으면 심각한 TCP 성능 저하를 초래할 수 있다. 이에 대하여 IEEE 802.16 시스템의 ARQ는 총 4가지의 타이머(timer)들이 존재하지만 그 구체적인 값들은 표준에서 다루고 있지 않다. 본 연구는 이러한 ARQ 타이머들의 값에 따라 TCP 성능이 어떻게 변하는지를 시뮬레이션을 통해 분석하고 적절한 값을 제시한다.

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