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전치왜곡 방식을 이용한 전력증폭기의 선형성 개선에 관한 연구 (A Study on the Linearity Improvement of Power Amplifier by Predistortion Method)

  • 김동일;황재현;유치환
    • 한국항해학회지
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    • 제24권5호
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    • pp.417-422
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    • 2000
  • The 3rd order intermodulation(IM3) signals affect a great influence on fundamental signal because IM3 can not be rejected by a filter. To solve this problem, in this paper, a predistortion method was applied. The designed predistorter cascaded to 4 W power amplifier and tested with two-tone spreaded 5 MHz. As an experimental result, it was cleary shown that the 3rd order intermodulation distortion characteristics has been improved as much as 17 dB when the output of the power amplifier is 30.67 dB.

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A NOTE ON KADIRI'S EXPLICIT ZERO FREE REGION FOR RIEMANN ZETA FUNCTION

  • Jang, Woo-Jin;Kwon, Soun-Hi
    • 대한수학회지
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    • 제51권6호
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    • pp.1291-1304
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    • 2014
  • In 2005 Kadiri proved that the Riemann zeta function ${\zeta}(s)$ does not vanish in the region $$Re(s){\geq}1-\frac{1}{R_0\;{\log}\;{\mid}Im(s){\mid}},\;{\mid}Im(s){\mid}{\geq}2$$ with $R_0=5.69693$. In this paper we will show that $R_0$ can be taken $R_0=5.68371$ using Kadiri's method together with Platt's numerical verification of Riemann Hypothesis.

Benfuracarb 원제에 함유된 불순물들의 glutathione-S-transferase와 amidase 저해 특성 (Inhibition of glutathion-S-transferase and amidase by impurities in technical grade benfuracarb)

  • 염창섭;김성문;유지숙;허장현
    • 농약과학회지
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    • 제6권1호
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    • pp.31-35
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    • 2002
  • 본 논문의 목적은 benfuracarb 원제(90.2%)에 함유된 불순물의 glutathione-S-transferase와 amidase에 대한 저해 특성과 해당 불순물의 구조를 밝히는데 있다. Benfuracarb 원제, 유효성분 및 불순물은 glutathione-S-transferase(GST)를 효과적으로 저해하였으나, 그 저해력은 GST 효소 저해제인 ethacrynic acid의 저해력보다는 낮았다. 즉, GST에 대한 benfuracarb 원제, 유효성분 및 불순물의 $I_{50}$은 각각 $9.7{\times}10^{-4}M,\;>1.0{\times}10^{-3}M,\;1.8{\times}10^{-4}M$이었으나, ethacrynic acid의 $I_{50}$$1.7{\times}10^{-5}M$이었다. Benfuracarb 원제, 유효성분 및 불순물은 amidase를 저해하였는데, 이들의 효소저해력은 iprobenfos의 저해력($I_{50},\;8.2{\times}10^{-7}M$)보다는 낮은 $6.0{\times}10^{-5}M,\;4.3{\times}10^{-4}M,\;7.6{\times}10^{-5}M$이었다. Benfuracarb 원제에는 4종의 불순물(IM $1{\sim}4$)이 검출되었는데, 이들 중 IM 2와 3은 GST와 amidase의 활성을 저해하였던 반면, IM 4는 효소활성을 저해하지 않았다. 이들 불순물 중 효소활성 저해특성을 갖는 IM 2와 3을 IR, $^1H$-NMR, $^{13}C$-NMR, LC-MS를 이용하여 구조를 분석한 결과, IM 2는 ethyl-N-isopropylamino propionate로, 그리고 IM 3은 ethyl-N-isopropyl-N-(chlorosulfenyl) aminopropionate로 확인되었다.

Effects of binder type and heat treatment temperature on physical properties of a carbon composite bipolar plate for PEMFCs

  • Kang, Dong-Su;Roh, Jea-Seung
    • Carbon letters
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    • 제14권2호
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    • pp.110-116
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    • 2013
  • This study investigated a developed process for producing a composite bipolar plate having excellent conductivity by using coal tar pitch and phenol resin as binders. We used a pressing method to prepare a compact of graphite powder mixed with binders. Resistivity of the impregnated compact was observed as heat treatment temperature was increased. It was observed that pore sizes of the GCTP samples increased as the heat treatment temperature increased. There was not a great difference between the flexural strengths of GCTP-IM and CPR-IM as the heat treatment temperature was increased. The resistivity of GPR700-IM, heat treated at $700^{\circ}C$ using phenolic resin as a binder, was $4829{\mu}{\Omega}{\cdot}cm$ which was best value in this study. In addition, it is expected that with the appropriate selection of carbon powder and further optimization of process we can produce a composite bipolar plate which has excellent properties.

트리즈(발명문제해석이론) 소개 및 적용 예 (Introduction and application of TRIZ (Theory of Inventive Problem Solving))

  • 윤길수
    • 한국해양공학회:학술대회논문집
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    • 한국해양공학회 2003년도 춘계학술대회 논문집
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    • pp.69-71
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    • 2003
  • This paper introduces TRIZ. TRIZ is the theory of inventive problem solving which haws started by G.Altschuler since 1946, Russia. TRIZ is applicable for not only mechanical engineering, but also science, economic and pedagogy fields. Characteristics of some kind of softwares for TRIZ method are briefly reviewed Especially Catia with IMC TechOptimizer is studied in detail and it is expected to be applicable well for the Ocean Engineering fields, if applicably applied for IM-Principles, IM-Predictions and IM-Effects, even though it will need much efforts and time to study. As an application example of TRIZ, Self-expandable anchor which is pending for patent is presented briefly.

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중국 모바일 인스턴트 메시징 서비스의 지속사용 의도에 관한 실증연구 (An Empirical Study on User's Continuance Intention Towards Mobile IM Service in China)

  • 라위의;소정;이영찬
    • 경영정보학연구
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    • 제15권2호
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    • pp.91-110
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    • 2013
  • 최근 카카오톡, 라인, 위챗 등과 같은 모바일 인스턴트 메시징(IM) 서비스는 낮은 전환비용으로 인해 치열한 경쟁을 펼치고 있다. 따라서 서비스 업체 입장에서는 모바일 IM 서비스 이용자의 지속적인 사용의도에 영향을 미치는 요인들을 파악하는 것이 무엇보다도 중요하다고 할 수 있다. 이를 위해 본 연구에서는 네트워크 효과(network externalities)와 인지된 서비스 품질을 모바일 IM 서비스의 지속적인 사용의도의 외생변수로 고려하였다. 여기서 네트워크 효과는 직접 효과(네트워크 크기)와 간접 효과(보완적 서비스)를 모두 포함한다. 중국 모바일 서비스 사용자를 대상으로 실증분석을 수행한 결과 '네트워크 크기'는 '인지된 유용성'에, '보완적 서비스'는 '인지된 즐거움'에 유의한 영향을 미치는 것으로 나타났다. 또한 '인지된 서비스 품질'은 예상대로 '고객만족' 뿐만 아니라 '인지된 유용성'과 '인지된 즐거움' 모두에 유의한 영향을 미치는 것으로 나타났다. 한편, 인지된 유용성 및 인지된 즐거움은 '고객만족'을 통한 간접적인 영향 이외에도 '지속적인 사용의도'에 직접적으로도 유의미한 영향을 미치는 것으로 나타났다.

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한국형 SNS의 진화 : 카카오톡 사례를 중심으로 (The Evolution of Korean Social Network Service focusing on the Case of Kakao Talk)

  • 정희석
    • 디지털융복합연구
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    • 제10권10호
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    • pp.147-154
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    • 2012
  • 한국형 SNS의 성장 가능성을 알아보기 위해 국내 1위 모바일 IM인 카카오톡 사례를 중심으로 분석해본 결과 다음의 사항들을 발견할 수 있었다. 첫째, 카카오톡은 PC상의 메신저 서비스와 다르게 모바일 IM 서비스를 바탕으로 소셜서비스 회사로 진화하고 있었다. 둘째, 카카오톡은 다양한 소셜서비스(사진기반 카카오스토리, 게임 마케팅 플랫폼 게임센터 등)를 시도하여 성공적으로 SNS 회사로 안착하였다. 셋째, 트위터의 사례처럼 플러스친구를 통한 뉴스 서비스, 아바타 및 앱스토어 등을 통해서 소셜미디어 및 소셜플랫폼 회사로 진화하고 있었다. 이런 한국시장에서 카카오톡의 성공은 NHN의 라인을 통해 일본 및 동남아시장에서 확대 재생산되고 있다. 라인은 카카오톡의 다양한 검증된 SNS 실험들을 일본시장에 적용시킴으로써 그 성공을 이어가려고 하고 있다. 온라인 웹서비스 싸이월드가 SNS로 세계시장에서 이루지 못한 것을 모바일 IM인 카카오톡, 라인은 그 성공 가능성을 한층 높여 주고 있다.

Efficacy of imatinib mesylate-based front-line therapy in pediatric chronic myelogenous leukemia

  • Oh, Hyun Jin;Cho, Mun Sung;Lee, Jae Wook;Jang, Pil-Sang;Chung, Nack-Gyun;Cho, Bin;Kim, Hack-Ki
    • Clinical and Experimental Pediatrics
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    • 제56권8호
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    • pp.343-350
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    • 2013
  • Purpose: Despite the established role of imatinib (IM) in chronic myelogenous leukemia (CML) in adults, there are few reports on its efficacy in children. In this study, we compared the outcomes of children with CML before and after the advent of IM-based treatment. Methods: The study cohort consisted of 52 patients treated for CML at the Department of Pediatrics, The Catholic University of Korea from January 1995 to October 2010. Patients were divided and analyzed according to the preImatinib group (pre-IMG) and imatinib group (IMG). Results: Median age at diagnosis for the overall cohort (pre-IMG, n=27; IMG, n=25) was 9 years, with a median follow-up duration of survivors of 84 months. Except for 5 patients in the IMG, all were diagnosed in chronic phase (CP). The overall survival (OS) of patients diagnosed in CP was 45.7% and 89.7% for pre-IMG and IMG, respectively (P=0.025). The OS of hematopoietic stem cell transplantation (HSCT) recipients in the 2 groups was similar, but the OS of patients diagnosed in CP who did not receive HSCT was superior in IMG (91.7% vs. 16.7%, P=0.014). Of the 12 patients in IMG who remained on IM without HSCT, 2 showed disease progression, compared to 11 of 12 in pre-IMG. No difference was observed in the progression free survival (PFS) of matched donor HSCT recipients and IM-based treatment recipients. Conclusion: Similar PFS of patients treated with IM and those who received matched donor HSCT underscore the potential of IM as effective first-line treatment in childhood CML.

경주마에서의 Acepromazine Maleate 투여에 따른 임상증상과 혈액상의 변화 조사 (Observation on the Clinical Sign and Blood Pictures of Thoroughbred Racehorses with Acepromazine)

  • 김병선;임영재;최희인;박성준
    • 한국임상수의학회지
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    • 제11권1호
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    • pp.419-426
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    • 1994
  • Acepromazine maleate(sedaject) was injected to 3 and 5 thoroughbred racehorses at 0.2mg/kg/bw, intramurculary(IM) and 0.1mg/kg/bw, intravenously(IV) respectively, and investigated the changes of clinical signs and blood pictures In before and after injection. Sedation was induced within 15 minutes after injection at the two groups and general sedation with towering of the upper eyelids and penile protrusion lasted about 7~9 hours and 9~11 hours at IV group and IM group following injection respectively. Heart beat and respiratory rates were induced within 15 minutes and then slowly returned to preinjection levels at 3 and 7 hours in the two group following injection respectively. Body temperature was decreased within IS minutes and the effect was Peaked after 30 minutes and 3 hours in IV group and IM group respectively, and then slowly returned to preinjection levels. RBC parameters, Hb and PCV were decreased about 30% at 1~5 hours and then returned to preinjection values at 13~24 hours in two groups Total WBC number were decreased slightly within 30 minutes and then returned to preinjection level at 13~24 hours in IV group but being still decreased 24 hours after dosing in IM group serum glucose level, SGOT and ALP activity were not changed significantly. Generally the set of sedation and awakening signs were faster in IV group than in IM group and RBC parameters and total WBC were depressed markedly in IM group than in IV group.

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The Mitochondrial Fusion-Related Proteins Mfn2 and OPA1 are Transcriptionally Induced during Differentiation of Bone Marrow Progenitors to Immature Dendritic Cells

  • Ryu, Seung-Wook;Han, Eun Chun;Yoon, Jonghee;Choi, Chulhee
    • Molecules and Cells
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    • 제38권1호
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    • pp.89-94
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    • 2015
  • The shape and activity of mitochondria are tightly regulated by fusion and fission processes that are essential for maintaining normal cellular function. However, little is known about the involvement of mitochondrial dynamics in the development of the immune system. In this study, we demonstrate that mitochondrial dynamics play a role in the differentiation and migration of immature dendritic cells (imDCs). We show that mitochondrial elongation is induced during GM-CSF-stimulated differentiation of bone marrow progenitors to imDCs accompanied by upregulation of mitochondrial fusion proteins. These processes precede the changes in mitochondrial morphology and connectivity that occur during differentiation. Mfn2 and OPA1, but not Mfn1, are transcriptionally upregulated during differentiation; however, knockdown of Mfn2 and OPA1 does not induce any change in expression of CD11c, CDC80, or CD86. Notably, knockdown of Mfn2 or OPA1 by siRNA in imDCs significantly reduces CCR7 expression and CCL19-mediated migration. These results suggest that the mitochondrial fusion-related proteins Mfn2 and OPA1 are upregulated during bone marrow progenitor differentiation and promote the migration of imDCs by regulating the expression of CCR7.