PVD-Be와 비정질 Zr-Be 합금을 용가재로 사용한 Zircaloy-4의 브레이징 접합부의 비교 연구

황용화(Hwang, Yong-Hwa),김재용(Kim, Jae-Yong),이형권(Lee, Hyung-Kwon),고진현(Koh, Jin-Hyun),오세용(Oh, Se-Yong) 한국산학기술학회 2006 한국산학기술학회논문지 Vol.7 No.2

중수로형 핵연료 제조공정 중 연료봉 피복관에 간격체와 지지체 등의 부착물이 브레이징으로 접합된다. 본 연구에서는 베릴륨을 물리 증착법(PVD)으로 접합될 부착물의 표변에 증착한 것과 비정질 용가재[Zr₁-xBex(0.3≤x≤0.5)]를 사용하여 브레이징된 접합부의 미세조직과 경도 등의 특성을 비교하고 브레이장 온도가 접합부에 미치는 영향 조사하였다. 비정질 용가재에 의한 정합층의 두께는 PVD-Be의 경우와 비교하여 더 얇았고, Be 함량이 감소할수록 접합층의 두께는 감소하였으며 모재의 침식은 거의 없었다. PVD-Be의 경우 공정 반응, 액상 출현, 모세관 현상과 확산으로 브레이징 되나 비정질 합금은 용가재 만이 용융되어 액상 접합되는 것으로 사료된다. PVD-Be 접합부의 미세 조직은 계변에서 수지상이 형성되어 내부로 성장하나, 비정질 합금에 의한 접합부는 석출된 제2상들이 구상으로 구성 되며 브레이징 온도가 증가할수록 구상은 더욱 커졌다. 비정질 합금 접합부의 경도는 Be 함량이 감소할수록 경도는 증가하였다. 본 연구에 사용된 비정질 합금 중 합금은 접합부에서 Be의 모재로의 확산이 적어 부드러운 계면과 모재의 침식이 없었고 높은 경도 때문에 핵연료 피복재 접합에 가장 적합한 용가재로 사료된다. Brazing is an important manufacturing process in the fabrication of Heavy Water Reactor fuel rods, in which bearing and spacer pads are joined to Zircaloy-4 cladding tubes. The physical vapor deposition(PVD) technique is currently used to deposit metallic Be on the surfaces of pads as a filler metal. Amorphous Zr-Be binary alloys which are manufactured by rapid solidification process are under developing to substitute the conventional PVD-Be coating. In the present study, brazed joint with PVD and amorphous alloys of Zr₁-xBe, (0.3≤;x≤0.5) as filler metals are compared by mechanism, microstructure and hardness. The thickness of brazed joint with amorphous alloys became much smaller than that of PVD-Be. The erosion of base metal did not occur in the brazed joint with amorphous alloys. The brazing mechanism for PVD-Be seems to be Be diffusion into Zr-4 with capillary action resulting from eutectic reaction while that for amorphous alloys are associated with the liquid phase formation in the brazed joint. The brazed joint microstructure with PVD-Be consists of dendrite while that with amorphous alloys is globular. The Zr0.7Beo.3 alloy shows the smooth interface with little erosion in the base metal and is recommended a most suitable brazing filler metal for Zircaloy-4.

PVD에 의한 연약점토지반의 압밀촉진효과에 대한 수치해석

유승경(You Seung-Kyong) 한국토목섬유학회 2009 한국지반신소재학회 논문집 Vol.8 No.1

본 논문에서는 연약지반개량공법 중의 하나인 PVD공법에 의한 연약지반개량효과를 파악하기 위하여 일련의 수치해석을 실시하였다. 본 연구에서는 기존에 수행된 실내모형실험 결과와의 비교를 통하여 그 신뢰성이 검증된 탄점소성 3차원압밀 유한요소해석 방법을 사용하였다. 수치해석에서는 PVD의 폭과 상재하중의 크기를 다양하게 변화시키며 개량된 점토지반의 압밀거동을 재현하였으며 그 결과를 이용하여 개량된 연약점토지반의 압밀촉진효과에 미치는 PVD의 폭과 상재하중 크기의 영향에 대하여 고찰하였다. In this paper, a series of numerical analyses on soft clay ground improved by PVD were carried out, in order to investigate the consolidation promotion effect considering PVD width and surcharge pressure. In the numerical analyses, an elasto?viscoplastic three?dimensional consolidation finite element method was applied, in which the applicability of numerical analyses could be confirmed comparing with consolidation behavior simulated at the laboratory. And, through the results of the numerical analyses, consolidation behaviors of soft clay ground with elapsed time was elucidated, together with the effects of PVD width and surcharge pressure.

LOCALLY PSEUDO-VALUATION DOMAINS OF THE FORM D[X]Nv

장규환 대한수학회 2008 대한수학회지 Vol.45 No.5

Let D be an integral domain, X an indeterminate over D, Nv = {f ∈ D[X]|(Af )v = D}. Among other things, we introduce the concept of t-locally PVDs and prove that D[X]Nv is a locally PVD if and only if D is a t-locally PVD and a UMT-domain, if and only if D[X] is a t-locally PVD, if and only if each overring of D[X]Nv is a locally PVD. Let D be an integral domain, X an indeterminate over D, Nv = {f ∈ D[X]|(Af )v = D}. Among other things, we introduce the concept of t-locally PVDs and prove that D[X]Nv is a locally PVD if and only if D is a t-locally PVD and a UMT-domain, if and only if D[X] is a t-locally PVD, if and only if each overring of D[X]Nv is a locally PVD.

Plasma thermal performance of a dual-process PVD/PS tungsten coating on carbon-based panels for nuclear fusion application

Kim, H.,Lee, H.J.,Kim, S.H.,Jang, C. North-Holland 2016 Fusion engineering and design Vol.109 No.1

Various tungsten (W) coating techniques have been used for the application of plasma facing material in nuclear fusion devices, which resulted in limited success. In this study, a dual-process W coating structure was developed on a graphite substrate to improve the thermal performance of the coating structure. The dual-process coating structure consisted of a thin (~7μm) multilayer W/Mo physical vapor deposition (PVD) coating layer deposited on top of the relatively thick (~160μm) plasma spray (PS) W coating on a graphite substrate panel. Then the coated sample was exposed to plasma heat flux of 1-3MW/m<SUP>2</SUP> for 300s. With addition of a thin surface PVD coating layer, the microstructure change in underlying PS W coating was substantially reduced compared to the simple PS W coating structure. The thickness of overall coating structure was maintained for the dual-process PVD/PS coated samples after the thermal loading tests, while a significant reduction in thickness due to surface erosion was observed for the simple PS W coated samples. The improvement in surface erosion resistance in the dual-process coating structure was discussed in view of the characteristics of PVD and PS coating layers.

LOCALLY PSEUDO-VALUATION DOMAINS OF THE FORM D[X]_Nv

Chang, Gyu-Whan Korean Mathematical Society 2008 대한수학회지 Vol.45 No.5

Let D be an integral domain, X an indeterminate over D, $N_v = \{f{\in}D[X]|(A_f)_v=D\}.$. Among other things, we introduce the concept of t-locally PVDs and prove that $D[X]N_v$ is a locally PVD if and only if D is a t-locally PVD and a UMT-domain, if and only if D[X] is a t-locally PVD, if and only if each overring of $D[X]N_v$ is a locally PVD.

판상 연직배수재의 유효 등가경 결정 방법에 관한 연구

유승경,小田 和廣 한국지반공학회 2008 한국지반공학회논문집 Vol.24 No.6

In the design of ground improvement using band-shaped prefabricated vertical drains (PVD), it is required to determine a reasonable equivalent circle of PVDs. In this paper, a series of numerical analyses on soft clay ground improved by PVD were carried out in order to investigate the resonable equivalent circle of PVD considering consolidation behavior of improved soft clay ground by PVD. The applicability of numerical analyses, in which an elasto-viscoplastic three-dimensional consolidation finite element method was applied, could be confirmed comparing with consolidation behavior simulated at the laboratory. And, through the results of the numerical analyses, consolidation behaviors of soft clay ground with elapsed time were elucidated, together with the equivalent circle of PVD considering consolidation behaviors.

PVD 코팅 방법에 의한 TiC, TiN의 윤활특성 연구

오성모 ( Seong-mo Oh ),전찬열 ( Chan-yeal Jeon ) 한국환경기술학회 2006 한국환경기술학회지 Vol.7 No.4

자동차 구조용 재료에 대하여 PVD코팅방법에 의한 윤활 특성을 연구 하였다. 코팅 재료는 탄화티탄(TiC)과 질화티탄(TiN)이다. 실험은 펠렉스 마찰 마모시험기를 이용하여 하중과 온도에 다양한 조건을 적용하여 마찰과 마모 거동에 대하여 윤활 특성을 결정하고 평가하였다. 연구결과 코팅하지 않았을 때보다 코팅하였을 때가 윤활 특성이 향상 되었고, 특히 내마모성 및 극압성 그리고 열 안정성이 훌륭하였다. We have studied on the tribological characteristics of Plasma Vapour Deposition (PVD) coating method in Automotive Structural Materials. Coating materials were deposited by the Titanium carbide(TiC) and Titanium nitride(TiN). An experimental process was established to determine the tribological characteristics of friction and wear behaviour with the variation of applied load, temperature and the time with the Falex friction and wear test machine. It was improved that when the surface modification of hard coatings(TiC, TiN) was deposited steel, the tribological characteristics become better. It is argued that it is improved because of excellence of the anti-wear, the extreme pressure properties and the heat stability.

PVD법을 이용한 전자파 차폐용 시트 제조 및 차폐효율 특성

채성정 ( Seong Jeong Chae ),홍병표 ( Byung Pyo Hong ),이병수 ( Byoung Soo Lee ),변홍식 ( Hong Sik Byun ) 한국공업화학회 2010 공업화학 Vol.21 No.5

Fe계 metal powder를 이용하여 최적화된 전자파차폐 시트를 제조한 후, 제조된 시트에 physical vapor deposition (PVD) 법으로 여러 금속들을 증착시켜 최종 전자파차폐용 시트를 제조하였다. 또한 증착된 금속들의 전자파 효율 특성을 분석하기 위하여 polyvinylidene fluoride (PVdF) 나노섬유 막을 시트로 활용하였다. 전기적 특성을 알아보기 위해 4-point probe로 측정하였으며, energy dispersive spectroscopy (EDS)를 이용하여 제조된 sheet에 금속이 증착되었음을 확인하였다. 차폐효율은 전자파차폐효율측정기를 이용하여 측정하였다. 전기저항은 1000 Å일 때 Cu에서 641.95 Ω·cm로 가장 낮은 저항 값을 나타내었다. 전자파 차폐효율은 증착된 금속의 두께의 증가에 따라 증가되었으며, Cu가 1000 Å으로 증착된 sheet가 최고 효율인 32.5 dB을 나타내었다. The optimized sheet for EMI shielding was prepared by metal power with Fe series. Then various metal powders were deposited on the sheet by PVD method. Moreover, the PVdF nanofiber membrane was used to compare the characteristic of EMI shielding efficiency of various metal powders. The electrical property was measured by the 4-point probe method. The result from EDS confirmed that the metal powder existed on the sheet. EMI shielding efficiency was analysed by EMI shielding measurement apparatus. The lowest electrical resistance, 641.95 Ω·cm, was obtained with 1000 Å deposition of Cu on the sheet. It was revealed that the EMI shielding efficiency increased with increase of the metal deposition thickness. The sheet deposited by Cu with 1000 Å showed the highest EMI shielding efficiency, 32.5 dB.

시간 의존적 배수저항을 고려한 방사방향 압밀곡선 예측법

김래현,홍성진,정두석,이우진 한국지반공학회 2008 한국지반공학회논문집 Vol.24 No.6

The existing equations for radial consolidation cannot account for the changes of well resistance with time and cannot predict the appropriate in-situ consolidation curve. In this study, small cylinder cell tests are performed to evaluate the discharge capacity of PVD. Also, a block sample of 1.2 m in diameter and 2.0 m in height was consolidated to observe the change in the drainage capacity with time for three types of PVD. From the test results on a block sample, the drainage curves normalized with initial drainage of each PVD are similar, regardless of the PVD type and the consolidation curve, which is predicted using solutions of radial consolidation based on the discharge capacity measured in a small cylinder cell tests, significantly overestimates the degree of consolidation. The term of well resistance in the radial consolidation solution was back-calculated to fit the consolidation curve of a large block sample and it is defined as the time dependent well resistance factor, L(t). The L(t) was found to be linearly proportional to the dimensionless time factor, Th. It was also shown that the consolidation curve evaluated by using L(t) provides more accurate prediction than the existing solution.

PVD를 활용한 C-ITS 차량 내 경고정보 제공에 따른 주행 및 환경영향 분석

김윤미,김호선,강경표,김승범 한국ITS학회 2023 한국ITS학회논문지 Vol.22 No.5

C-ITS (Cooperative-Intelligent Transportation System) refers to user safety-oriented technology and systems that provide forward traffic situation information based on a two-way wireless communication technology between vehicles or between vehicles and infrastructure. Since the Daejeon-Sejong pilot project in 2016, the C-ITS infrastructure has been installed at various locations to provide C-ITS safety services through highway and local government demonstration projects. In this study, a methodology was developed to verify the effectiveness of the warning information using individual vehicle data collected through the Gwangju Metropolitan City C-ITS demonstration project. The analysis of the effectiveness was largely divided into driving behavior impact analysis and environmental analysis. Compliance analysis and driving safety evaluation were performed for the driving impact analysis. In addition, to supplement the inadequate collection of Probe Vehicle Data (PVD) collected during the C-ITS demonstration project, Digital Tacho Graph ( DTG ) data was additionally collected and used for effect analysis. The results of the compliance analysis showed that drivers displayed reduced driving behavior in response to warning information based on a sufficient number of valid samples. Also, the results of calculating and analyzing driving safety indicators, such as jerk and acceleration noise, revealed that driving safety was improved due to the provision of warning information.