• 제목/요약/키워드: PP&E

검색결과 242건 처리시간 0.032초

전기철도 급전계통의 고조파 억제용 RC뱅크의 적정 위치에 관한 연구 (Optimal Location of RC bank limiting Harmonics in Electric Railway System)

  • 이한민;오광해;창상훈
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2001년도 하계학술대회 논문집 B
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    • pp.1254-1256
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    • 2001
  • This paper composes the Electric Railway System with the common grounding based on the 5-port network model. We compare the magnification ratio of harmonic currents according to locations of RC bank(i.e s/s. sp, and pp). It takes a lot of costs to equip the RC-bank at all location. And it is NOT effective that RC-bank is equipped at S/S. Finally, this paper proposes SP as the optimal site of RC-bank aspect reducing harmonic.

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도서관학 교수법

  • 정재선
    • 도서관문화
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    • 제18권3호
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    • pp.17-23
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    • 1977
  • 도서관학에서 교과과정과 교수법을 분리해서 생각할 수 는 없다. 특히 교수법의 중요성은 누구나 공감하고 있으나 지금까지 도서관학은 자체에 알맞은 교수법이 개발되지 못한채, 전통적인 교수법을 답습해오던가 아니면 법률학, 경제학 등 다른 학문분야의 교수법을 그대로 도입해왔기 때문에, 도서관학교수법이 한계를 벗어나지 못하였던 것이다. 그리고 도서관학교수법에 관한 문헌도 좀처럼 보기드물며, 설상 있다고 하여도 대부분이 그 이론을 체계화시키지 못하고 도서관학교육운영상의 절차와 기술만을 다루고 도서관학에 적합한 교수법을 다루지 않은 것이 그 특징이라 할 수 있다. 이 책은 Josefa E. Sabor 교수가 저술한 ${method}^s$ of Teaching librarianship (Paris: Unesco, 1969)에 수록되어 있는 Curriculum을 번역한 것이다. 1976년 8월 Lausanne에서 개최된 IFLA, 총회에서 도서관학교분과위원회(Section of Library Schools)가 “도서관학교의 기준, 1976”(Standards for Library School, 1976, IFLA Journal vol.2, No.4, 1976, pp.209-223)의 “Curriculum" 조항(p.220)에서 이 책을 권장한 것만 보더라도, 이 책은 종전의 도서관학교수법을 탈피해서 실제로 도서관학에 적합한 교수법을 시사한 것이라고 볼 수 있다.

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정 공청 장군 유품에 대한 연구 (A Study for the Armor of General Jung, Gong-chung)

  • 배상경
    • 대한가정학회지
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    • 제35권2호
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    • pp.111-122
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    • 1997
  • This thesis researched for the conservation of a suit of armor, one glove, one belt, and on knife case that General Jung, Gong-chung had been worn in the early 17 th centuries. The armor was Doojung-kab for the battle. It was made of two kinds of fabrics, one of them was silk satin's outer fabrics, the other was quilt4d cotton's lining. as the armor was made of silk and cotton, it was treated by dry solvents and dry soap. In the dry cleaning method, used solvents were n-hexane, cyclohexane, benzene, and n-decane. the volume ratio of dry soap was 120: 1. The reaction temperature was 30℃, and reaction time was 10 to 30 minutes per one turn. The glove, belt and knife case were made with leather. They were dipped on the polyethyleneglycol 150 saturated solution during 24hours at 50℃ and then dried naturally. They were washed by toluene to remove the untreated pp.E.G. on the surfaces. It was sterilized by two gases of methylenebromide and ethyleneoxied. For the conservation, it was packed thoroughly by ? polyethylene film sheet without air.

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저온.고온고습 환경시험에 의한 GFRP의 미시계면 접착상태 및 노치형상강도 특성에 관한 연구 (A study on characteristic adgesive condition at microscopic interfaces and notch shape strength of GFRP composites laminates under low-hot-wet environment)

  • 김옥만;박귀성;한길영;이동기;김이곤
    • 한국해양공학회지
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    • 제10권4호
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    • pp.58-66
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    • 1996
  • The purpose of this investigation is to estimate the strength with the variations of the notch shape and the adgesive condition at the fiber/matrix micro interface of E-glass/PP laminates. To promote the degradation of the adhesive condition at the fiber/matrix micro interface without matrix dissolution loss, low-, hot-wet and spiking tests were carried out. The absorpotion properties and the tensile properties were compared accrding to the fiber orientation and the content. The results show that, firstly, saturated moisture absorption was reached at 5cycles and their absorptions of RD-40, UD-42 and UD-50 are 0.68%, 0.63%, 0.60%, respectively. Secondly, all the specimens investigated were mostly degraded at 5cycle, whereas UD-50 having ellipse shaped notch the least decrement of strength.

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고세장비 플라스틱 나노헤어 성형에 관한 연구 (A study on high aspect ratio of plastic nano hair molding)

  • 김태훈;유영은;서영호;이학주;박영우
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 2006년도 춘계학술대회 논문집
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    • pp.471-472
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    • 2006
  • High aspect ratio of nano hairs on a plastic substrate is molded using thermoplstic materials including COC, PP, PC and PMMA. As a template for molding nano hairs, AAO membrane is adopted, which is 60um thick and 13mm in diameter. This membrane has about 109 of through-holes of which diameter is around 200nm. This AAO membrane and the pellet of materials are stacked in the mold and pressed to mold after heating up to be melted. The AAO membrane is removed using KOH to obtain the molded nano hairs. As a result, the diameter of the molded hairs is around 200nm and the length is $2um{\sim}60um$ depending on the molding conditions and materials.

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PE-MOCVD로 증착된 Hf(C,N) 박막의 Cu에 대한 확산 방지 특성

  • 노우철;조용기;김영석;정동근
    • 한국진공학회:학술대회논문집
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    • 한국진공학회 1998년도 제14회 학술발표회 논문개요집
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    • pp.39-40
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    • 1998
  • Diffusion barrier characteristics of hf(C,N) thin films for Cu metalliztion was investgated. Hf(C,N) thin films were depposited on Si(100) suvstrates by ppulsed D. C pplasma enhanced metal-organic chemical vappor depposition (ppE-MOCVD) using Tetrakis diethyl amido hafnium (Hf[NC2H5)2]4 : TDEAHf) and N2 as pprecursors. X-ray diffraction analyses sheet resistance measurment and Rutherford backscattering sppectroscoppy analyses revealed that HF(C,N) films pprevent diffusion of Cu fairly well upp to $600^{\circ}C$. At $700^{\circ}C$ however Hf(C,N) films allowed a significant diffusion of Cu into the Si substrate.

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Mechanical and Water Barrier Properties of Biopolyester Films Prepared by Thermo-Compression

  • Rhim, Jong-Whan
    • Food Science and Biotechnology
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    • 제16권1호
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    • pp.62-66
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    • 2007
  • Four different biopolyester films, two aliphatic polyesters including polylactides (PLA) and poly(3-hydroxy-butyrate-co-3-hydroxyvalerate (PHBV), and two aliphatic-aromatic copolyesters including Ecoplex and Biomax, were prepared using by thermo-compression, and their tensile and water barrier properties were determined. Among the films tested, PLA film was the most transparent (T: 95.8%), strongest, and stiffest (TS, 40.98 MPa; E, 1916 MPa), however it was rather brittle. In contrast, Ecoplex film was translucent while being the most flexible and resilient (EB, 766.8%). Biomax film was semitransparent and was the most brittle film tested (EB, 0.03%). All biopolyester films were water resistant exhibiting very low water solubility (WS) values ranging from 0.0.3 to 0.36%. PHBV film showed the lowest water vapor permeability (WVP) value ($1.26{\times}10^{-11}\;g{\cdot}m/m^2{\cdot}sec{\cdot}Pa$) followed by Biomax, PLA, and Ecoflex films, respectively. The water vapor barrier properties of each film were approximately 100 times higher than those of carbohydrate or protein-based films, but about 100 times lower than those of commodity polyolefin films such as low-density polyethylene (LDPE) or polypropylene (PP).

Conduction Mechanism for PAP and Comparison of Physical Properties of PAP with other Polyaniline-based Conducting Polymers

  • Choi, Kyung-Moon;Lee, Eun-Ju;Kim, Keu-Hong
    • Bulletin of the Korean Chemical Society
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    • 제11권5호
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    • pp.371-376
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    • 1990
  • Polyaniline perchlorate (PAP) was synthesized by the chemical oxidation of aniline using ferric perchlorate as a strong oxidant. The electrical conductivity of PAP was measured at temperatures from - 170 to 25$^{\circ}C$. It is suggested from the conductivity measurements that the conduction mechanism for PAP is a polaron hopping conduction. From the dependence of resistivity on the reciprocal temperature, the activation energy was computed to be 0.072 eV. From the comparison of the ESR parameterks and conductivity at 25$^{\circ}C$ for the polyaniline-based conducting polymers, the conductivities of PAP, PATFB and PATS increase with increasing ${\Delta}H_{pp}$, decreasing A/B ratio and decreasing g-value, respectively. It is shown by TGA results for PAP, PATFB and PATS that the maximum weight loss rates (Pr) are 0.185 (at 269$^{\circ}C$ ), 0.366 (at 324$^{\circ}C$) and 0.23 mg/min (at 338$^{\circ}C$), respectively.

CORRIGENDUM ON "ORIENTED TRANSFORMATIONS ON A FINITE CHAIN: ANOTHER DESCRIPTION" [COMMUN. KOREAN MATH. SOC. 38 (2023), NO. 3, PP. 725-731]

  • Vitor H. Fernandes
    • 대한수학회논문집
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    • 제39권3호
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    • pp.643-645
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    • 2024
  • In this note, we aim to correct some of the results presented in [1]. Namely, the statements of Proposition 2.1, Corollary 2.2, Corollary 2.3, Theorem 2.4 and Theorem 2.6, concerning only the monoids 𝓞𝓟n and 𝓟𝓞𝓟n, have to exclude transformations of rank two. All other results of [1], as well as those mentioned above but for the monoids 𝓞𝓡n and 𝓟𝓞𝓡n, do not require correction.

폐암세포주에서 Heme Oxygenase-1의 역할 (The Role of Heme Oxygenase-1 in Lung Cancer Cells)

  • 정종훈;김학렬;김은정;황기은;김소영;박정현;김휘정;양세훈;정은택
    • Tuberculosis and Respiratory Diseases
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    • 제60권3호
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    • pp.304-313
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    • 2006
  • 연구배경 : Heme oxygenase-1 (HO-1)은 heme의 분해 대사과정에 관여하는 유도성 효소로 heme을 분해하여 biliverdin, free iron, 및 일산화탄소 등을 생성시킨다. HO-1의 발현은 다양한 스트레스성 자극에 반응하여 생체방어 기능을 갖는 것으로 알려져 있는데 세포성장이나 세포사 특히 세포고사를 조절하는 것으로 보고되고 있다. 현재 신장암, 전립선암, 간암, 육종 등의 고형암에서 발현됨이 알려져 있고, 실제 HO-1 억제제를 투여했을 때 암성장이 억제됨이 보고되었다. 저자들은 폐암세포주들에서 HO-1의 발현유무와 그 역할을 규명하고 나아가 HO-1 억제제의 치료제로서의 가능성을 알아보고자 하였다. 방 법 : 비소세포폐암세포주인 A549, H23, NCI-H157, NCI-H460을 이용하였다. 세포독성은 MTT 방법으로 구하였고, HO-1의 발현은 Western blotting으로 확인하였다. HO의 효소활성은 시간당 세포단백질의 mg당 형성된 빌리루빈의 양을 이용하여 측정하였다. 또한 $H_2O_2$의 생성은 horse radish peroxidase(HRP)와 형광물질인 2',7'-dichlorofluorescein(DCF)를 이용한 두 가지 방법을 이용하였다. A549세포에 HO-1 small interfering RNA(siRNA)을 주입하여 유식세포 분석과 caspase-3에 대한 Western blotting을 통하여 세포고사유무를 확인하였다. 결 과 : 비처리 상태에서 다른 세포주에 비해 A549세포의 HO-1 발현이 증가되었으며 HO-1 활성억제제인 ZnPP를 처리하였을 때 생존율의 의미 있는 감소를 보였다. 이러한 소견과 일치하여 ZnPP는 용량의존적으로 HO 의 효소활성 감소와 세포 내 $H_2O_2$ 생성의 증가를 초래하였다. 또한 HO-1 siRNA로 주입된 A549세포는 세포고사를 유도하였다. 결 론 : HO-1은 폐암의 치료에 있어서 새로운 분자생물학적 기전의 가능성을 제시하여 HO-1에 대한 표적치료의 가능성을 보여줄 것으로 기대된다.