• 한국세라믹학회지
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• 제33권12호
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• pp.1414-1420
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• 1996

평균 입경 8${\mu}{\textrm}{m}$ Si 분말을 사용하여 무가압 분말 충전 성형볍에 의해 Si 성형체를 제조하였다. 이 Si 성형체를 1350,140$0^{\circ}C$의 온도에서 3~35시간동안 N2/H2 분위기에서 반응 소결한 후 미세구조를 관찰하였다. 반응 소결체는 90% 이상의 질화율과 88%의 상대밀도를 보였다. 반응 소결체의 가스압 소결을 위해 소결조제로서 MgO를 Mgnitrate 수용액 형태로 Si 성형체에 5wt% 첨가한 후140$0^{\circ}C$에서 15시간동안 반응 소결하였다. 이후 반응 소결체를 1800, 1900, 200$0^{\circ}C$에서 각각 150, 300분 동안 가스압 소결을 행하여 95%의 상대밀도와 598 MPa의 꺾임강도, 6 MPa.m1/2의 파괴인성을 나타내는 질화규소 소결체를 제조하였다.

• 공업화학
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• 제20권5호
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• pp.536-541
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• 2009

플라즈마 중합 아크릴산 필름을 원격 플라즈마 방식으로 Si과 KBr 기판 위에 증착하였다. 플라즈마 출력, 반응 압력, 간접 플라즈마 방식이 필름의 성장속도, 화학적 구조 및 화학 결합 상태 등에 미치는 영향을 조사하였다. 화학 구조와 화학적 상태는 FT-IR, XPS 분석과 curve fitting 기법으로 분석하였다. 플라즈마 출력에 따른 필름의 성장속도는 100 W에서 포화값을 보이지만, 압력에 대해서는 300 mtorr에서 최대값을 나타내었다. 플라즈마 출력을 높이거나 압력을 낮추면 단위 입자들에게 가해지는 에너지 값(W/FM)이 증가하여 아크릴산 분자의 파괴가 촉진되었다. XPS curve fitting 분석 결과, W/FM값이 커질수록 카르복실 COO 결합은 감소하지만 에테르 C-O 결합과 카보닐 C=O 결합은 증가하여 서로 반대의 경향을 보임을 확인하였다.

• 마이크로전자및패키징학회지
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• 제21권1호
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• pp.1-6
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• 2014

고출력 LED 패키지의 열적 경로(thermal path)를 줄이기 위해 플립칩 본딩법에 대한 연구가 활발히 진행되고 있다. 본 연구에서는 Au-Sn 열압착 본딩 및 Sn-Ag-Cu(SAC) 리플로우 본딩을 이용하여 본딩 특성 및 열적특성을 비교 평가 하였다. Au-Sn 열압착 본딩은 50 N에서 $300^{\circ}C$의 접합온도로 본딩하였고, SAC 솔더는 솔더페이스트를 인쇄한 후 리플로우법으로 피크온도 $255^{\circ}C$에서 30 sec에서 본딩하였다. SAC 솔더를 사용한 LED 패키지의 전단강도는 $5798.5gf/mm^2$로 Au-Sn 열압착 본딩의 $3508.5gf/mm^2$에 비해 1.6배 높았다. 파단면과 단면분석 결과 Au-Sn, SAC 솔더 모두 LED 칩 내부에서 파단이 일어나는 것을 관찰하였다. 반면 Au-Sn 열압착 본딩 샘플의 열저항은 SAC솔더 접합 샘플에 비해 낮았으며, SAC 솔더 접합부 내부의 기공에 의해 열저항이 커짐을 알 수 있었다.

• 한국생산제조학회지
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• 제9권4호
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• pp.131-136
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• 2000

This study deals with the mechanical properties of STS304-Al351 friction welding zone. Main results are as follows ; under the condition of upset pressure 75MPa, the tensile strength of STS304-al6351 friction weld interface was higher than that of Al6351 base metal, and the highest tensile strength(290MPa) was obtained at upset pressure 125MPa. The hardness profile across the weld interface shows that the hardness of both STS304 and Al6351 is higher around the weld interface, and sharply increased hardness on the STS304 side is related with the plastic deformation of micro volume. As the result of analyzing the tensile fracture, it showed perfect soft fracture.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 춘계학술대회
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• pp.519-523
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• 2007

Gas(or methane) hydrates are solid solutions when water molecules are linked through hydrogen bonding and create host lattice cavities that can enclose a large variety of guest gas molecules. The natural gas hydrate crystal may exist at low temperature above the normal freezing point of water and high pressure greater than about 30 bars. A lot of quantities of natural gas hydrates exists in the earth and many production schemes are being studied. In the present investigation, depressurization method was considered to predict the production of gas and the simulation of the two phase flow - gas and water - in porous media is being carried out. The simulation show about the fluid flow in porous media have a variety of applications in industry. Results provide the appearance of gas and water production, the pressure profile, the saturation of gas/ water/ hydrates profiles and the location of the pressure front.

• Transactions on Electrical and Electronic Materials
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• 제4권2호
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• pp.10-14
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• 2003

Flexible displays such as plastic-based liquid crystal displays (LCDs) and organic light-emitting diode displays (OLEDDs) have been researched and developed at KETI since 1997. The plastic film substrate is very weak to heat and pressure compared to glass substrate, that its fabrication process is limited to 110$^{\circ}C$ and low pressure. The ITO films were deposited on the bare plastic film substrate by rf-magnetron sputtering. Moreover, in order to maintain uniform cell gap and pressure on the plastic film substrate, we utilized newly-invented jig and fabrication process. Electro-optical characteristics were better than or equivalent to those of typical glass LCDs though it is thinner, lighter-weight, and more robust than glass LCDs.

• Journal of Advanced Marine Engineering and Technology
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• 제31권6호
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• pp.761-767
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• 2007

We have developed novel optical-fiber sensors based on strain-induced long-period fiber gratings for monitoring the deformation of a hull. They have no external pressure for sustaining the mechanical formed gratings. The pressure, which provides a force to form the periodic grating along the single mode fiber, was realized by the bonding strength of a photopolymer. To reduce the polarization dependency of the sensors caused by the asymmetry structure of gratings, a Faraday Rotator Mirror (FRM) was utilized in this experiment. We have realized the polarization-insensitive function of the proposed sensors. The change of an external strain are measured by an optical spectrum analyzer. When the external stain increases. the attenuation at the resonant wavelength decreases and the loss peak was slightly shifted to the shorter wavelength.

• International Journal of Safety
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• 제9권1호
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• pp.43-46
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• 2010

In the recycle process of organic solvent, the atmospheric oxygen can cause autoxidation and product peroxide. The time-saving method to evaluate the hazards has been required. In this study, oxygen pressure monitoring experiment was proposed as a new method to evaluate autoxidative resistances of solvents. Some of organic solvents were pressurized by oxygen and kept under isothermal condition. At the same time, the pressure in the vessel tracked. Iodometrical titration, thermal analysis and spectroscopic analysis were performed to measure peroxide concentration, the heat of reaction and chemical bonding change. From the results that THF has larger oxygen consumption rate than CPME, it is considered that autoxidative resistance of THF is lower than that of CPME. This method enables to obtain results in shorter time than other methods. These experimental results were consistent with the previous research with longer test durations [1-2].

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.1
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• pp.147-150
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• 2003

In this paper, We fabricated a high temperature pressure sensor using SBD(silicon- direct-bonding) wafer of $Si/SiO_2$/Si-sub structure. This sensor was very sensitive because the piezoresistor is fabricated by single crystal silicon of the first layer of SDB wafer. Also, it was possible to operate the sensor at high temperature over $120^{\circ}C$ which is the temperature limitation of general silicon sensor because the piezoresistor was dielectric isolation from silicon substrate using silicon dioxide of the second layer. The sensitivity of this sensor is very high as the measured result of D2200 shows $183.6\;{\mu}V/V{\cdot}kPa$. Also, the output characteristic of linearity was very good. This sensor was available at high temperature as $300^{\circ}C$.

• 소성∙가공
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• 제19권7호
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• pp.423-428
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• 2010

Carbon nanotubes(CNTs) are expected to be ideal reinforcements of metal matrix composite materials used in aircraft and sports industries due to their high strength and low density. In this study, a high pressure torsion(HPT) process at an elevated temperature(473K) was employed to achieve both powder consolidation and grain refinement of aluminummatrix nanocomposites reinforced by 5vol% CNTs. CNT/Al nanocomposite powders were fabricated using a novel molecular-level mixing process to enhance the interface bonding between the CNTs and metal matrix before the HPT process. The HPT processed disks were composed of mostly equilibrium grain boundaries. The CNT-reinforced ultrafine grained microstructural features resulted in high strength and good ductility.