• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2009년 추계학술발표대회
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• pp.66-66
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• 2009

Various alloy system, such as Cu-Sn-Ti, Cu-Ag-Ti, and Ni-B-Cr-based alloy are used for the brazing of diamond grits. However, the problem of the adhesion strength between the diamond grits and the brazed alloy is presented. The adhesion strength between the diamond grits and the melting filler alloy is predicted by the contact angle, thereby, instead of diamond grit, the study on the wettability between the graphite and the brazing alloy has been indirectly executed. In this study, Cu-13Sn-12Ti filler alloy was manufactured, and the contact angles, the shear strengths and the interfacial area between the graphites(diamond grits) and braze matrix were investigated. The contact angle was decreased on increasing holding time and temperature. The results of shear strength of the graphite joints brazed filler alloys were observed that the joints applied Cu-13Sn-12Ti alloy at brazing temperature 940 $^{\circ}C$ was very sound condition indicating the shear tensile value of 23.8 MPa because of existing the widest carbide(TiC) reaction layers. The micrograph of wettability of the diamond grit brazed filler alloys were observed that the brazement applied Cu-13Sn-12Ti alloy at brazing temperature $990^{\circ}C$ was very sound condition because of existing a few TiC grains in the vicinity of the TiC layers.

• 상하수도학회지
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• 제29권1호
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• pp.89-96
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• 2015

Smart water grid is a water network with communication to save water and energy using various water resources. In smart water grid, water product from the various sources can be blended to be supplied to end-users. The product water blending was reported by literatures while feed water blending has been rarely reported so far. In this work, a commercial reverse osmosis (RO) system design software provided by a membrane manufacturer was used to elucidate the effect of feed water blending on the performance of seawater reverse osmosis (SWRO) plant. Fresh water from exisiting water resource was assumed to be blended to seawater to decrease salt concentration of the RO feed water. The feed water blending can simplify the RO system from double to single pass and decrease seawater intake amount, the unit prices of the RO system components including high pressure pump, and operation risk. Due to the increase in RO plant capacity with the feed water blending, however, the RO membrane area and total power consumption increase at higher water blending rates. Therefore, a specific benefit-cost analysis should be carried out to apply the feed water blending to SWRO plants.

• Journal of Welding and Joining
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• 제28권3호
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• pp.49-58
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• 2010

Various alloy system, such as Cu-Sn-Ti, Cu-Ag-Ti, and Ni-B-Cr-based alloy are used for the brazing of diamond grits. However, the problem of the adhesion strength between the diamond grits and the brazed alloy is presented. The adhesion strength between the diamond grits and the melting filler alloy is predicted by the contact angle, thereby, instead of diamond grit, the study on the wettability between the graphite and the brazing alloy has been indirectly executed. In this study, Cu-13Sn-12Ti filler alloy was manufactured, and the contact angles, the shear strengths and the interfacial area between the graphites (diamond grits) and braze matrix were investigated. The contact angle was decreased on increasing holding time and temperature. The results of shear strength of the graphite joints brazed filler alloys were observed that the joints applied Cu-13Sn-12Ti alloy at brazing temperature $940^{\circ}C$ was very sound condition indicating the shear tensile value of 23.8 MPa because of existing the widest carbide(TiC) reaction layers. The micrograph of wettability of the diamond grit brazed filler alloys were observed that the brazement applied Cu-13Sn-12Ti alloy at brazing temperature $990^{\circ}C$ was very sound condition because of existing a few TiC grains in the vicinity of the TiC layers.

• Composites Research
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• 제36권5호
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• pp.377-382
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• 2023

그래핀 기반 소자의 성능을 개선하기 위해서는 그래핀과 기판 사이의 계면 상호 작용을 이해하는 것이 중요하다. 본 연구에서는 유전체 기판에 놓인 단일층 그래핀의 접착에너지를 모드 I 시험을 통해 측정하였다. 메탄과 수소 가스 분위기에서 화학기상증착법(CVD)을 통해 구리 포일 위에 대면적 단일층 그래핀을 합성하였다. 합성한 그래핀을 폴리머를 이용한 습식 전사 공정을 통해 유전체 기판 위에 전사하였다. 이중외팔보 형상을 이용한 모드 I 시험을 통해 기판 위에 올려진 그래핀을 기계적으로 박리하였다. 이 때, 얻어지는 힘-변위 곡선을 분석하여 접착에너지를 평가하였는데, 산화실리콘 기판에 대해서는 1.13 ± 0.12 J/m², 질화실리콘 기판에 대해서는 2.90 ± 0.08 J/m²의 접착에너지를 나타냈다. 본 연구를 통해 유전체 기판 위에 올려진 CVD 그래핀의 계면 상호 작용력에 대해 정량적인 측정을 진행하였다.

• Nuclear Engineering and Technology
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• 제44권8호
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• pp.871-888
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• 2012

This paper aims at presenting the state of the art, the recent progress, and the perspective for the future, in the modelling of two-phase flow in the horizontal legs of a PWR. All phenomena relevant for safety analysis are listed first. The selection of the modelling approach for system codes is then discussed, including the number of fluids or fields, the space and time resolution, and the use of flow regime maps. The classical two-fluid six-equation one-pressure model as it is implemented in the CATHARE code is then presented and its properties are described. It is shown that the axial effects of gravity forces may be correctly taken into account even in the case of change of the cross section area or of the pipe orientation. It is also shown that it can predict both fluvial and torrential flow with a possible hydraulic jump. Since phase stratification plays a dominant role, the Kelvin-Helmholtz instability and the stability of bubbly flow regime are discussed. A transition criterion based on a stability analysis of shallow water waves may be used to predict the Kelvin-Helmholtz instability. Recent experimental data obtained in the METERO test facility are analysed to model the transition from a bubbly to stratified flow regime. Finally, perspectives for further improvement of the modelling are drawn including dynamic modelling of turbulence and interfacial area and multi-field models.

• Restorative Dentistry and Endodontics
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• 제33권4호
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• pp.405-412
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• 2008

본 연구의 목적은 여러 가지 계면조건의 변화를 통해서 layering시 복합레진 층간의 결합에 oxygen inhibition layer (OIL)가 필수적인지를 고찰해보는 것이다. 가로 $\times$ 세로 $\times$ 두께가 16 $\times$ 28 $\times$ 2.5 mm인 알루미늄판에 지름 3.7 mm의 구멍을 형성하여 몰드를 제작하고 다음과 같이 복합레진 (Z-250, 3M ESPE)을 충전하여 광중합하였다. 1 군: 하층판에 복합레진을 충전하고 광중합 한 후, 상층판을 접합하고 레진을 충전하여 광중합을 하였다 (OIL를 남김). 2 군: 하층판에 복합레진을 충전하고 광중합 한 후 acetone에 적신 cotton으로 문질러서 OIL를 제거하고 상층판을 접합하여 복합레진을 충전하고 광중합을 하였다 (OIL를 제거). 3 군: 하층판에 복합레진을 충전하고 Mylar strip을 접합하여 공기와의 접촉을 차단한 후 광중합을 하였다. Mylar strip을 제거하고 상층판을 접합 후 복합레진을 충전하여 광중합을 하였다 (OIL형성을 억제). 4 군: 하층판에 복합레진을 충전하고 광중합 한 후 glycerin을 OIL 표면에 도포하고 다시 광중합하였다. 상층판을 접합하여 복합레진을 충전하고 광중합을 하였다 (OIL를 중합). 5군 (대조군): 하층판과 상층판의 경계에 복합레진층의 계면이 위치하지 않도록 복합레진을 bulk충전하였다 (계면형성 없이 bulk 충전한 복합레진). 24 시간 100% 습도에서 보관 후 상층판과 하층판 사이의 계면 전단결합강도를 측정하고 파절 양상을 관찰하였다. 계면을 통한 중합과정의 확산을 관찰하기 위하여 제조한 광개시제가 들어있지 않은 실험적 복합레진 (Exp_Com)을 몰드에 충전하고 상부에 flowable 복합 레진 (Aelite Flow) 또는 접착레진 (ScotchBond Multipurpose)을 접촉시킨 후 광조사하였다. 몰드내의 미중합된 Exp_Com을 acetone bath 에서 5 분 동안 제거한 후 몰드내에 다시 Aelite Flow를 충전하고 광중합을 시행하였다. 경화된 복합레진 시편의 단면을 관찰하여 Exp_Com 층의 두께를 측정하였다. OIL를 배제하거나 중합시킨 2-4군은 OIL이 존재하는 1 군과 통계적으로 유의한 결합강도의 차이를 보이지 않았으며, Mylar strip을 이용하여 OIL의 생성을 억제했던 3군과 glycerin을 도포하여 OIL를 중합시킨 4군은 계면을 생성하지 않은 대조군인 5 군과도 통계적으로 유의한 차이를 보이지 않았다. 중합과정의 확산에 의해 중합개시제가 포함되지 않은 Exp_Com내에 중합된 층이 생겨난 것을 시각적으로 확인할 수 있었으며, Exp_Com의 중합층 두께는 flowable 레진의 경우 20.95 (0.90) um였고 접착레진의 경우 42.13 (2.09) 였다.

• Composites Research
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• 제20권3호
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• pp.55-62
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• 2007

Jute와 Hemp 섬유/폴리프로필렌 (PP)의 내구성 및 계면 평가는 끓는 물 실험 전 후로 해서 조사되었고 끓는 물 실험 전 후에 따른 Jute와 Hemp 섬유의 수분함량은 TCA를 통해 측정되었다. 끓는 물 실험 후, Jute, Hemp섬유와 폴리프로필렌 기지재 사이의 계면전단강도와 기계적 물성은 감소하였다. 반면에 물에 의해 부풀어 오른 미소섬유에 의해 미처리경우와 비교해서 접착일은 증가를 하였다. 그리고 끓는 물 실험 전·후의 Jute, Hemp섬유와 폴리프로필렌의 표면에너지는 동 접촉각을 통해 얻어졌다. 계면전단강도는 항상 열역학의 접착일과 일치하지는 않는다. 끓는 물 내에서, Jute와 Hemp 섬유는 물에 의해 부풀어지게 된다. 그래서 표면적과 수분 침투공간이 증가한다. 끓는 물 실험 전 후의 Jute와 Hemp 섬유 미세파괴 경향은 명백하게 다르다. Jute와 Hemp 섬유/폴리프로필렌 복합재의 환경적 영향에 의한 미세파괴 형태는 광학 현미경을 통한 관찰과 음향 방출 수와 에너지에 의해 상호 일치함을 보여주었다. 끓는 물 실험 이후, Jute 섬유는 Hemp 섬유와 달리 부풀어진 피브릴에 의한 낮은 인장강도에서 나타나는 미세파괴 형태를 보여주었다. 또한, 부풀어진 피브릴에 의해 미세파괴시 음향 방출 수는 증가를 하였으며, AE 진폭과 에너지는 감소하였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.1876-1881
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• 2007

The micro plated heat exchangers were designed to transfer more heat/volume or mass than previous heat exchangers within the context of the design constraints specified. The increase of the surface-to-volume ratio results in an increase of the interfacial area. This enhances considerably the performance of a heat exchanger. This can be an important component in a wide range of applications fuel cell, aerospace, automotive, electronic system and home heating, etc). In this study, the performance evaluation of micro plated heat exchangers under the counter flows with straight and S-shaped channel are carried out. The pressure drop as well as inlet and outlet fluid temperature were measured at steady state under various operating conditions and the total heat transfer rate were also calculated.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.248-248
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• 2016

We have investigated the crystallinity, preferential ordering, and interfacial stability of 1,4,5,8,9,11-hexaazatriphenylene-hexanitrile (HATCN) thin film interconnected with organic/inorganic multilayer. At the region close to the organic-organic interface, HATCN formed low crystalline order with substantial amorphous phase. As film growth continued, HATCN stacked with high crystalline phase. After a sputtering deposition of the indium zinc oxide (IZO) layer on top of HATCN/organic layer, the volume fraction of preferentially ordered HATCN crystals increased without any structural deterioration. In addition, the HATCN surface was kept quite stable by preserving the sharp interface between HATCN and sputtering deposited IZO layers.

• KSBB Journal
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• 제16권3호
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• pp.241-245
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• 2001

Mass transfer rates have been measured for the extraction of enzyme from aqueous solution into a reverse-micelle phase at $25^{\circ}C$. The 420 mL vessel was carefully designed to maintain a planar interface between the aqueous and solvent phases, so allowing precise measurement of interfacial area, has been investigated. Sodium di-2-ethylhexyl sulfosuccinate(AOT) was the surfactant used. Factors varied included: agitator speed, pH, ionic strength and surfactant concentration. Samples were taken from the solvent phase at 15min intervals, and the amount of enzyme extracted was measured by UV absorption at 280 nm. The observed Sherwood numbers for the aqueous phase $Sh_1$were correlated interms of the aqueous phase Reynolds number $Re_1$, and modified Schmidt number $Sc_1$. $Sh_1=0.664Re_1^{0.5}Sc_1^{0.33}$