• 한국해양공학회지
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• 제4권2호
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• pp.94-99
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• 1990

This paper deals with investigating experimentally the effects of PWHT on the weld quality such as strength, toughness, hardness and micro-structure of the welded joints in friction welding of torsion bar material SUP9A bar to bar. The results obtained are summarized as follows; 1) It was certified that the condition of the post-weld heat treatment(PWHT) for the friction welded joints was very satisfactory because both strength and toughness of the joints were improved as almost same as those of the base metal or better by the PWHT. 2) The peak of hardness distribution of the friction welded joints can be eliminated by PWHT, resulting in being almost equalized at the weld interface, the HAZ(heat affected zone) and the base metal. 3) The micro-structure of the base meta., HAZ and weld interface(WI) of friction welded joints welded at the optimum welding condition consists of the same sorbite structure obtained by PWHT and fined sorbite at WI, resulting in increasing toughness as well as strength, and no micro structural defect has been found at the friction welded zone.

• 한국해양공학회지
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• 제4권2호
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• pp.244-244
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• 1990

This paper deals with investigating experimentally the effects of PWHT on the weld quality such as strength, toughness, hardness and micro-structure of the welded joints in friction welding of torsion bar material SUP9A bar to bar. The results obtained are summarized as follows; 1) It was certified that the condition of the post-weld heat treatment(PWHT) for the friction welded joints was very satisfactory because both strength and toughness of the joints were improved as almost same as those of the base metal or better by the PWHT. 2) The peak of hardness distribution of the friction welded joints can be eliminated by PWHT, resulting in being almost equalized at the weld interface, the HAZ(heat affected zone) and the base metal. 3) The micro-structure of the base meta., HAZ and weld interface(WI) of friction welded joints welded at the optimum welding condition consists of the same sorbite structure obtained by PWHT and fined sorbite at WI, resulting in increasing toughness as well as strength, and no micro structural defect has been found at the friction welded zone.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집 Vol.14 No.1
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• pp.133-136
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• 2001

In this paper, we investigated the diffraction efficiency of polarization holography using by amorphous $Ag/As_{40}Ge_{10}Se_{15}S_{35}$ multi-layer thin films by He-Ne laser. Multi-layer structures were formed by alternating a layer of meta1(Ag) and chalcogenide( $Ag/As_{40}Ge_{10}Se_{15}S_{35}$ ). The holographic grating in these thin flims has been formed using a linealy polarized He-Ne laser light (633nm). The diffraction efficiency was investigated the two sample of $Ag/As_{40}Ge_{10}Se_{15}S_{35}-7$ layers and $Ag/As_{40}Ge_{10}Se_{15}S_{35}-15$ layers. As the results, we found that the diffraction efficiency of $Ag/As_{40}Ge_{10}Se_{15}S_{35}-7$ layers and $Ag/As_{40}Ge_{10}Se_{15}S_{35}-15$ layers were 1.7% and 2.5% respectively.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 춘계학술대회 논문집 초전도 자성체
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• pp.55-58
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• 2002

PIT method which is used at fabricating Bi-2223/Ag HTS wire includes a drawing process, conventional deformation method. Drawing of meta1(Ag) and ceramic (BiSrCaCuO) composite is also difficult and significant for uniform deformation. In this paper, parameters of uniform deformation was studied at Bi-2223/ Ag multifilamentary HTS wire. Powder and rod as a starting precursor was compared at 55 filament and 54 filament Bi-2223/Ag HTS wire, respectively. Micro-hardness and area COV of the filaments was also evaluated when the diameters were decreased through drawing operations.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 추계학술대회 논문집
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• pp.29-32
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• 1999

$GaF_3$ films were directly grown on p' and p-type GaAs(100) substrates using a $SF_6$ plasma discharge system. GaAs MIS(Meta1-Insulator-Semiconductor) capacitor was successfully fabricated for about 1 hour at temperature $290^{\circ}C$ using the as-grown $GaF_3$ films. The as-grown films on p'-GaAs exhibited a current density of less than 6.68 $\times$ $1O^{-9}$ A/$cm^2$ at a breakdown field of 500kV/cm and a refractive index of 2.0 ~ 2.3 at a wavelength of 632.8 nm. The dielectric constant was about 5 derived from 1 MHz capacitance-voltage (C-V) measurements. Dielectric dispersion of the fluoridated films on p'-GaAs measured ranged from 100 Hz to 10 MHz was not observed.

• 한국전기전자재료학회논문지
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• 제22권2호
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• pp.163-168
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• 2009

Hyperbranched conjugated polymers (p-HPPV and m-HPPV) with para and meta linkages were synthesized from $A_2$ and $B_4$ type monomers through Wittig polycondensation. The synthesized p-HPPV and m-HPPV were completely soluble in common organic solvents such as chloroform, tetrahydrofuran, 1,2-dichloroethane, etc. and thermal gravimetric analyses showed that p-HPPV and m-HPPV are stable up to $350^{\circ}C$. The molecular weights (from GPC), UV-visible, and photoluminescence maximum peaks of p-HPPV and m-HPPV are characterized in detail. The fabricated EL devices using the synthesized hyperbranched polymers, (ITO/(p-HPPV or m-HPPV)/Al), showed EL emission at about 507 nm and 481 nm (681 nm), respectively. Especially, EL device from m-HPPV were found to exhibit nearly white emission with approximate CIE coordinates of (0.31, 0.34) compared with (0.310, 0.316) of NTSC white color at $100\;cd/m^2$. The good photophysical properties combine with good film-form ability could make these hyperbranched polymers to be a potential candidate for the EL materials.

• 한국전기전자재료학회논문지
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• 제34권1호
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• pp.27-32
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• 2021

In this study, we fabricated multilayer graphene on a glass substrate by stacking the monolayer graphene synthesized via chemical vapor deposition. The electrical sheet resistance and optical transmittance were evaluated to confirm the quality of the stacked multilayer graphene. Using the fabricated multilayer graphene/glass structure, we characterized its thermal radiative property in terms of the integrated emissivity. The integrated emissivity of the multilayer graphene/glass structure was tuned from 0.91 to 0.72 when the number of graphene layers was changed from 1 to 12. We also demonstrated that the emissivity tunability provided a way to control the apparent temperature of an object that can be used in infrared stealth applications.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2010년도 춘계학술대회
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• pp.159-160
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• 2010

본 논문에서는 항만물류용 RFID(Radio Frequency IDentification) 시스템에서 사용하는 중심주파수 433 MHz에서 동작하는 전파흡수체에 흡수재료로 사용되는 AMP (비정질금속분말 ; Amorphous Meta1 Powder)와 Sendust의 전파흡수 특성을 비교하였다. 먼저 AMP와 Sendust를 지지재인 CPE(Chlorinated Polyethylene)를 이용하여 조성비 85 : 15 wt.%의 전파흡수체 샘플을 제작한 후, 입력임피던스를 측정하여 샘플의 재료정수를 계산하고 시뮬레이션에 의하여 최적의 전파흡수체를 설계하였다. 그 결과 AMP와 Sendust의 복소비 투자율 허수항이 다르다는 것을 확인하였으며 433 MHz 주파수대역에서 복소비투자율의 값이 더 높은 AMP의 흡수능이 더 우수한 것을 확인하였다.

• 한국건설순환자원학회논문집
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• 제4권4호
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• pp.105-110
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• 2009

본 연구에서는 고가의 실리카흄의 대체재로 활용가능한 메타카올린, HMBA의 치환율에 따른 고강도모르타르의 유동특성 및 역학특성에 대하여 비교 분석하여 그 성능을 규명하여 실리카흄의 대체재로 활용가능성을 위한 기초자료를 제시하고자 하였다. 본 연구의 유동특성 및 역학특성 실험결과 굳지않은 모르타르에서 목표 플로우를 도달하기 위하여 치환율이 커질수록 고성능감수제의 첨가량이 증가하였으며, 공기량은 치환율이 증가할수록 감소하는 경향을 나타냈다. 또한, 역학특성에서 압축강도, 인장강도, 휨강도에서는 Plain보다 실리카흄과 메타카올린 HMBA을 치환한 배합이 강도가 높았으며, 치환율이 커질수록, 재령이 증가할수록 압축강도는 증가하는 경향을 나타냈으며, 각각의 혼화재를 치환한 배합의 강도는 큰 차이를 나타내진 않았지만, HMBA보다 실리카흄과 메타카올린을 치환한 배합이 강도가 다소 높은 경향을 나타냈다. 따라서, 메타카올린과 HMBA를 첨가한 모르타르의 유동특성 및 역학특성을 비교 분석한 결과 고가의 실리카흄의 대체재료로 활용가능성을 확인 할 수 있었다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2004년도 봄 학술발표회 논문집
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• pp.309-316
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• 2004

A probabilistic structural integrity assessment is performed for a reactor pressure vessel under PTS(Pressurized Thermal Shock). A semi-elliptical finite axial crack is assumed to he in the beltline region(either base metal or weld meta)1 of the reactor vessel inside surface. The selected random variables are initial crack depth, neutron fluence on the vessel inside surface, copper, nickel, and phosphorus content of the vessel material, and RT/sub NDT/. The probabilities of crack initiation or vessel failure where the crack is propagated through vessel wall are calculated. The probabilities obtained with random crack size are compared to these obtained with deterministic us. Since the failure function cannot to explicitly by selected by selected random variables, Monte Carlo Simulation is applied to perform probabilistic analysis The influence of the amount of neutron fluence is also examined to assess the structural reliability for vessel life time.