• 제목/요약/키워드: Q&A

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I/Q 불균형이 고려된 DVB-S2 시스템의 심벌 오류 확률 (Symbol Error Probability of DVB-S2 System with I/Q Unbalances)

  • 임인철;원승찬;윤동원;박상규
    • 한국통신학회논문지
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    • 제32권9C호
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    • pp.810-819
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    • 2007
  • 90도 위상 천이기나 필터와 같은 불완전한 시스템 요소에 의해 생성되는 I(inphase)축과 Q(quadrature)축 간의 불균형은 피할 수 없는 물리적 현상으로 동기 변/복조 시스템(coherent modulation/demodulation system) 구현에 있어서 성능 열화를 유발한다. 본 논문에서는 AWGN (additive white Gaussian noise) 채널 환경에서 수신기의 I/Q 불균형이 존재하는 경우, DVB(digital video broadcasting)-S2 시스템에서 사용되는 변조방식에 대한 정확하고 일반화된 심벌 오류 확률을 2차원 결합 가우시안 Q-함수(two-dimensional joint Gaussian Q-function)의 선형 결합(linear combination)의 형태로 유도한다.

ISO/IEC 18000-3 ASK 모드와 PJM 모드의 성능 비교 (Performance Comparison of ISO / IEC 18000-3 ASK and PJM Mode)

  • 김재림;양훈기
    • 한국ITS학회 논문지
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    • 제7권6호
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    • pp.70-80
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    • 2008
  • 본 논문에서는 18000-3 RFID 표준인 ASK 모드와 PJM 모드 RFID 시스템을 인식속도의 관점에서 비교하였다. ASK 모드와 PJM 모드 리더/태그간 통신 과정을 표현 할 수 있는 대표 블록들의 조합을 구성하여 블록이 발생한 횟수를 이용하여 인식속도를 비교하였다. FS-Aloha 기반 프로토콜을 적용시키기 위한 Q알고리즘으로 표준 기고서에서 예시로 제안한 알고리즘, Q값 고정 알고리즘, 최소 Q 알고리즘 그리고 남은 태그 수에 연동한 Q값 설정 알고리즘을 이용하였다. 시뮬레이션 과정을 통해서 Q알고리즘에 따른 ASK 모드와 PJM 모드 속도 비교뿐만 아니라 Q알고리즘을 고정시킨 후 ASK 모드와 PJM 모드의 인식속도를 비교하였고 속도에 영향을 미치는 파라메타들을 도출하였다.

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특정한 유한체 Fq상에서의 제곱근 알고리즘 (Square Root Algorithm in Fq for Special Class of Finite Fields)

  • 구남훈;조국화;권순학
    • 한국통신학회논문지
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    • 제38A권9호
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    • pp.759-764
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    • 2013
  • $q{\equiv}5$ (mod 8)의 경우에 유한체 $F_q$상에서 Atkin의 제곱근 알고리즘과 $q{\equiv}9$ (mod 16)의 경우에 Kong의 알고리즘으로부터 일반적인 제곱근 알고리즘을 제안한다. 우리의 알고리즘은 s가 $2^s|q-1$을 만족하는 가장 큰 양의 정수라 할 때, $2^s$차 원시근 ${\xi}$를 미리 계산하였고 s의 값이 작을 때 적용가능하다. 제시한 알고리즘은 제곱근을 계산하기 위해 한 번의 지수계산이 필요하고, Akin, M$\ddot{u}$ller, Kong의 알고리즘과 비교해보아도 유리하다.

CONTRACTIONS OF CLASS Q AND INVARIANT SUBSPACES

  • DUGGAL, B.P.;KUBRUSLY, C.S.;LEVAN, N.
    • 대한수학회보
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    • 제42권1호
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    • pp.169-177
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    • 2005
  • A Hilbert Space operator T is of class Q if $T^2{\ast}T^2-2T{\ast}T + I$ is nonnegative. Every paranormal operator is of class Q, but class-Q operators are not necessarily normaloid. It is shown that if a class-Q contraction T has no nontrivial invariant subspace, then it is a proper contraction. Moreover, the nonnegative operator Q = $T^2{\ast}T^2-2T{\ast}T + I$ also is a proper contraction.

Vortex Filament Equation and Non-linear Schrödinger Equation in S3

  • Zhang, Hongning;Wu, Faen
    • Kyungpook Mathematical Journal
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    • 제47권3호
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    • pp.381-392
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    • 2007
  • In 1906, da Rios, a student of Leivi-Civita, wrote a master's thesis modeling the motion of a vortex in a viscous fluid by the motion of a curve propagating in $R^3$, in the direction of its binormal with a speed equal to its curvature. Much later, in 1971 Hasimoto showed the equivalence of this system with the non-linear Schr$\ddot{o}$dinger equation (NLS) $$q_t=i(q_{ss}+\frac{1}{2}{\mid}q{\mid}^2q$$. In this paper, we use the same idea as Terng used in her lecture notes but different technique to extend the above relation to the case of $R^3$, and obtained an analogous equation that $$q_t=i[q_{ss}+(\frac{1}{2}{\mid}q{\mid}^2+1)q]$$.

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KT Test Set을 이용한 우리말 자연언어검색의 효율성에 관한 비교연구 (A Comparative Study on the Effectiveness of Hangul Natural Language Retrieval Using KT Test Set)

  • 이현아;김성혁
    • 한국정보관리학회:학술대회논문집
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    • 한국정보관리학회 1995년도 제2회 학술대회 논문집
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    • pp.37-40
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    • 1995
  • 본 연구는 자연언어시스템에서 색인어와 탐색어의 특정성에 기인하는 재현율 감소를 극복하기 위한 방법론으로써 탐색어의 확장을 통한 검색효율을 평가하였다. 이를 위하여 우리말 데이터베이스를 대상으로 주제전문가가 자연언어로 작성한 원 질의문 (Q1), 원 질의문에 사용된 탐색어와 데이터베이스내의 색인어간의 유사도를 이용하여 탐색어를 확장한 질의문 (Q2(0.2), Q2(0.3)), 주제전문가인 이용자가 Q1의 의미적인 관계를 고려해서 자연언어로 탐색어를 확장한 질의문 (Q3)을 검색효율면에서 비교하였다. 실험결과, 평균재현율은 Q2(0.2), Q2(0.3), Q3, Q1의 검색의 순이었다. 평균정확율은 Q3, Q2(0.3), Q1, Q2(0.2)검색의 순으로 나타났다.

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PROJECTIVE PROPERTIES OF REPRESENTATIONS OF A QUIVER Q = • → • AS R[x]-MODULES

  • Park, Sangwon;Kang, Junghee;Han, Juncheol
    • Korean Journal of Mathematics
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    • 제18권3호
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    • pp.243-252
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    • 2010
  • In this paper we extend the projective properties of representations of a quiver $Q={\bullet}{\rightarrow}{\bullet}$ as left R-modules to the projective properties of representations of quiver $Q={\bullet}{\rightarrow}{\bullet}$ as left $R[x]$-modules. We show that if P is a projective left R-module then $0{\rightarrow}P[x]$ is a projective representation of a quiver $Q={\bullet}{\rightarrow}{\bullet}$ as $R[x]$-modules. And we show $0{\rightarrow}L$ is a projective representation of $Q={\bullet}{\rightarrow}{\bullet}$ as R-module if and only if $0{\rightarrow}L[x]$ is a projective representation of a quiver $Q={\bullet}{\rightarrow}{\bullet}$ as $R[x]$-modules. Then we show if P is a projective left R-module then $R[x]\longrightarrow^{id}P[x]$ is a projective representation of a quiver $Q={\bullet}{\rightarrow}{\bullet}$ as $R[x]$-modules. We also show that if $L\longrightarrow^{id}L$ is a projective representation of $Q={\bullet}{\rightarrow}{\bullet}$ as R-module, then $L[x]\longrightarrow^{id}L[x]$ is a projective representation of a quiver $Q={\bullet}{\rightarrow}{\bullet}$ as $R[x]$-modules.

Promoter Methylation Status of Two Novel Human Genes, UBE2Q1 and UBE2Q2, in Colorectal Cancer: a New Finding in Iranian Patients

  • Mokarram, Pooneh;Shakiba-Jam, Fatemeh;Kavousipour, Soudabeh;Sarabi, Mostafa Moradi;Seghatoleslam, Atefeh
    • Asian Pacific Journal of Cancer Prevention
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    • 제16권18호
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    • pp.8247-8252
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    • 2016
  • Background: The ubiquitin-proteasome system (UPS) degrades a variety of proteins which attach to specific signals. The ubiquitination pathway facilitates degradation of damaged proteins and regulates growth and stress responses. This pathway is altered in various cancers, including acute lymphoblastic leukemia, head and neck squamous cell carcinoma and breast cancer. Recently it has been reported that expression of newly characterized human genes, UBE2Q1 and UBE2Q2, putative members of ubiquitin-conjugating enzyme family (E2), has been also changed in colorectal cancer. Epigenetics is one of the fastest-growing areas of science and nowadays has become a central issue in biological studies of diseases. According to the lack of information about the role of epigenetic changes on gene expression profiling of UBE2Q1 and UBE2Q2, and the presence of CpG islands in the promoter of these two human genes, we decided to evaluate the promoter methylation status of these genes as a first step. Materials and Methods: The promoter methylation status of UBE2Q1 and UBE2Q2 was studied by methylation-specific PCR (MSP) in tumor samples of 60 colorectal cancer patients compared to adjacent normal tissues and 20 non-malignant controls. The frequency of the methylation for each gene was analyzed by chi-square method. Results: MSP results revealed that UBE2Q2 gene promoter were more unmethylated, while a higher level of methylated allele was observed for UBE2Q1 in tumor tissues compared to the adjacent normal tissues and the non malignant controls. Conclusions: UBE2Q1 and UBE2Q2 genes show different methylation profiles in CRC cases.

농촌 지역 일부 노인에서 신체 기능 정도에 따른 활동 제한도, 비만도 및 영양소 섭취 수준의 변화 양상 비교 (Comparison of Self-living Ability, Obesity Indices and Nutrient Intake according to Physical Fitness among the Elderly in Rural Areas)

  • 서희재;김복희
    • 한국식품영양학회지
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    • 제22권4호
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    • pp.577-586
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    • 2009
  • Aging is associated with decreased energy expenditure, thermogenesis and energy requirements. Maintenance of physical fitness of the elderly has been reported to reduce the rate at which the basal metabolic rate, muscle strength, skeletal muscle mass and bone density deteriorate. Skeletal muscle disease is known to increase the risk of physical disability and psychological problems. This study was conducted to investigate changes in disability, emotional problems, body compositions, obesity indices and nutrient intake levels according to physical fitness with the elderly in rural areas. According to the results, physical fitness was negatively related with Activities of Daily Living(ADL, p<0.05), Instrumental Activities of Daily Living(IADL, p<0.001), Body Mass Index(BMI, p<0.001) and abdominal obesity(p<0.05), while it showed a positive correlation with the General Self Efficacy Scale(GSES)(p<0.001) and nutrient intake(p<0.05). When changes in these factors were compared according to the range of quartile of the Fullerton Advanced Balance Scale(FAB Scale), GSES(Q1=35.3, Q2=43.5, Q3=53.2, Q4=51.9, p<0.001), BMI(Q1=36.1%, Q2=34.7%, Q3=33.2%, Q4=28.6%, p<0.01), abdominal obesity(Q1=1.02, Q2=0.99, Q3=0.97, Q4=0.94, p<0.001) and nutrient intake(Q1=71.1%, Q2=75.4%, Q3=80.6%, Q4=80.2%, p<0.05) differed significantly. Taken together, these results suggested that better physical fitness would lead to a reduction in negative factors including physical disability and obesity indices, but to an increase in positive factors such as GSES and nutrient intake. The results of this study are expected to be used as basic data for the development of programs to promote the health of the elderly in a local society.

1993년부터 1995년 사이에 태어난 고등학생의 각 생년별 오운체질의 특징에 관한 연구 (A Study of Five Constitutions Amongst Korean High School Students Born from 1993 to 1995)

  • 진승희;김태희;최경미
    • 대한한의진단학회지
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    • 제15권1호
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    • pp.111-126
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    • 2011
  • Objectives: To characterize Five Woons in 1993, 1994 and 1995. Methods: A diagnostic questionnaire was given to 1066 High School students who were born in Korea from 1993 to 1995. One of the Five Woons was given to the participant based on his and her birthday. The oneway analysis of variance was applied to compare the means of the Five Woons in each year. Results: 1. Developed a reliable questionnaire consisting of 28 items for the purpose of chracterizing five constitutions. 2. Based on the Duncan method, significant differences were observed among the Five Woons in height, weight and BMI (p<0.1). For height, the score of Wood constitution was lowest. For weight the core of Soil constitution was lowest. 3. Based on the Duncan method, at the significant level (p<0.1), the Five Woons were different in each year (Gapsul year, Eulhae year, Gyeyoo year) for 28 items in the questionnaires: Q1, Q2,Q3, Q7, Q8, Q11, Q12, Q15, Q18, Q19, Q21, Q22, Q24, Q26, Q27 and Q28. Conclusions: Further clinical research is necessary to characterize five constitutions and also develop more delicate analyses and questionnaires. Also the diagnosis and corresponding treatments based on the Five Woons should be further studied in view of the Asian medicine.