• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.04b
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• pp.118-120
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• 2002

Electro-optical (EO) characteristics of the ion beam (IB) aligned twisted nematic (TN)-liquid crystal display (LCD) with oblique ion beam exposure on the diamond-like carbon (DLC) thin film surface were studied. An excellent voltage-transmittance (V-T) curve of the ion beam aligned IN-LCD was observed with oblique ion beam exposure on the DLC thin film surface for I min. Also, a faster response time for the ion beam aligned TN-LCD with oblique ion beam exposure on the DLC thin film surface for 1 min can be achieved.

• Transactions of the Korean Society of Mechanical Engineers
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• v.9 no.2
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• pp.158-173
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• 1985

An experimental investigation has been made to study the interaction between and incident oblique shock wave and an unstabilized turbulent boundary layer on a solid surface downstream of a porous surface with air injection through the porous surface. The boundary layer upstream of the interaction is unstabilized by the injection and provokes a shock wave which eventually interacts with the unstabilized boundary layer after reflecting from the upper wall of the test section. Three cases having diferent upstream Mach numbers and different shock strengthes are studied. According to the level of the unstabilization, two cases are of attached boundary layers and the other one is of a separated boundary layer. The result shows that the reflected wavey system is composed of the compression wave, expansion wave fan, and recompression wave like the ordinary interaction while the separated boundary layer strengthens the reflected expansion waves. The interactions of the attached boundary layers show a similar tendency of the upstream wall pressure distribution as that of the ordinary interacton but the pressure rise rather decays in the downstream region. In case of the separated boundary layer, the wall pressure continues to rise in the downstream as opposed ot the former cases. This indicates that the interaction region spreads out widely adn the viscous effect of the separated boundary layer smoothens the abrupt pressure increase due to the shock inpingement.

• The Korean Journal of Malacology
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• v.11 no.1
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• pp.70-77
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• 1995

The purpose of this study is to determine the differences of the conchiolin layer, prismatic layer and nacreous layer deposited within the shell of the freshwater family Unionidae. shether they possess species-specific characteristics and differences of the microstructure of these layers, A Scanning electron microscopic obwervations were conducted on seven species. The results indicate that all species possess thin and homogeneous layers within the periostracum. The prismatic layers of these species were composed of ednsely packed prisms. The prismatic layers of the shell in six species were typical shape of prisms. especially Inio douglasiae and Lamprotual gottschei. But, in Unio douglasiae sinuolatus, it was irregular and oblique prism shape.The nacreous layer of weven unionids characterized by possession of three types by lamillae shape: thin and homogeneous on genus Anodonta(0.4 pm size of lamella), Unio(1.3pm) and Lamprotual (1.7pm), homogeneous in shape and irregular in size of lamillae in Lanceolaria(1.0 pm)and irregulat in shape and size in Solenaia(0.2-0.4 pm). The microstructure of the naceous layer may be useful as a taxonomic character at the generic level.

• Journal of Mechanical Science and Technology
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• v.15 no.5
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• pp.665-670
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• 2001

The interaction of a travelling shock with the shear layer of a flat plate is studied computationally. The Euler and Navier-Stokes equations are solved numerically on quadrilateral unstructured adaptive grids. The flat plate is installed horizontally on the central axis of a shock tube. The shear layer is first created by two shock waves at different speeds splitted by a flat plate. A series of small vortices is developed as a consequence in the shear layer. The shock wave reflected at the end wall impinges the shear layer. The complicated shock dynamics in the evolution to the pseudo-steady state is represented with the morphological transformation of a planar shock into an oblique shock.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.11a
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• pp.327-330
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• 2006

Numerical study on the passive control of the oblique shock wave/turbulent boundary-layer interaction control utilizing slotted plates over a cavity has been carried out. Numerical results have been compared with the experimental observations, such as pitot/wall surface pressures and Schlieren flow visualizations, obtained for the same boundary conditions. It was found that the present numerical results shows a good agreement with experimental data. Further, the effect of different slot configurations including various number, location and angle of slots on the characteristics of the interactions are also tested, focusing on the variation of the piot pressure and the boundary-layer characteristics downstream of the interaction and the recirculating mass flux through cavity.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.98-98
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• 2013

완전화 박막이란 사용자가 원하는 용도에 맞게 최적의 성능을 구현하도록 제조된 박막을 의미하며 금속이나 화합물 박막을 제조하되 각종 구조 제어 Tool이나 증착 공정을 변화시켜 나노화와 다층화 또는 치밀화를 통해 구현될 수 있다. 최근 고성능의 증착 및 제어 Tool이 개발되고 빗각증착(Oblique Angle Deposition)이나 스침각 증착(Glancing Angle Deposition) 방법 등의 기술이 개발되면서 사용자 목적에 최적인 박막 소재를 제공하여 User-friendly한 응용을 위한 연구개발이 활발히 진행되고 있다. 완전화 박막 제조에 대한 시도는 1990년대에 일본에서 시작되었다. 일본에서는 산학연이 공동으로 참여하는 NEDO 프로그램을 통해 경질코팅을 이용한 Protective Layer를 제조하여 차단 방식에 의한 내식성 구현 연구를 수행하였다. 유럽에서는 제 7차 European Framework Program (7th FT)을 통해 2007년부터 CORRAL (Corrosion Protection with Perfect Atomic Layer) 프로젝트를 만들어 완전화 박막 연구를 진행하고 있다. 상기 프로젝트는 얇은 자연 산화막이 Bulk의 부식을 방지해주는 것에 착안하여 HIPIMS나 Filtered Arc 또는 ALD 공정을 이용하여 자연 산화막과 유사한 Defect-free 산화막을 제조하여 Barrier형 내식성 박막을 구현하는 것을 목표로 하고 있다. 본 연구에서는 완전화 박막 구현을 위한 연구동향을 파악하고 완전화 박막 제조를 위한 기술적 과제와 몇 가지의 시도에 대한 기초 연구 자료를 소개한다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.451-452
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• 2006

We studied the electro-optical characteristic of vertical alignment liquid crystal display(VA-LCD) on the $SiO_x$ thin film deposited $45^{\circ}$ oblique by rf magnetic sputtering system. LC alignment characteristic showed homeotropic alignment, and pretilt angle was about $90^{\circ}$. A uniform liquid crystal alignment effect on the $SiO_x$ thin film was achieved and the electro-optical characteristic of the $SiO_x$ thin film deposited $45^{\circ}$ oblique by rf magnetic sputtering system was excellent.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.75-78
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• 2004

Various jet engines (Turbine engine family and RAM Jet engine) have been developed for high speed aircrafts. but their application to hypersonic flight is restricted by principle problems such as increase of total pressure loss and thermal stress. Therefore, the development of next generation propulsion system for hypersonic aircraft is a very important subject in the aerospace engineering field, SCRAM Jet engine based on a key technology, Supersonic Combustion. is supposed as the best choice for the hypersonic flight. Since Supersonic Combustion requires both rapid ignition and stable flame holding within supersonic air stream, much attention have to be given on the mixing state between air stream and fuel flow. However. the wider diffusion of fuel is expected with less total pressure loss in the supersonic air stream. So. in this study the direction of fuel injection is inclined 30 degree to downstream and the total pressure of jet is controlled for lower penetration height than thickness of boundary layer. Under these flow configuration both streams, fuel and supersonic air stream, would not mix enough. To spread fuel wider into supersonic air an aerodynamic force, baroclinic torque, is adopted. Baroclinic torque is generated by a spatial misalignment between pressure gradient (shock wave plane) and density gradient (mixing layer). A wedge is installed in downstream of injector orifice to induce an oblique shock. The schlieren optical visualization from side transparent wall and the total pressure measurement at exit cross section of combustor estimate how mixing is enhanced by the incidence of shock wave into supersonic boundary layer composed by fuel and air. In this study non-combustionable helium gas is injected with total pressure 0.66㎫ instead of flammable fuel to clarify mixing process. Mach number 1.8. total pressure O.5㎫, total temperature 288K are set up for supersonic air stream.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.29 no.6
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• pp.621-629
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• 2011

According to the development of technologies for generating the 3D spatial information, the needs for producing and updating the precise 3D objects with LoD 4 level are increased. On the other hand, the needs for real-time updating of 2D digital maps are expanded, based on the execution of various GIS projects. These 2D informations can be extracted from precisely constructed 3D spatial information, to do this the feasibility studies on extraction of the 2D information from the 3D spatial information is needed. In this study, 3D objects are modeled using multi-oblique images, and the objects are stereo-plotted using digital airborne images, as well. Then the two data sets are compared and analyzed. The results show that the accuracy assessments fulfill the 1/1,000 digital map accuracy standard of regulations for photogrametric surveying of National Geographic Information Institute, but the shapes and the areas of building objects are different between two data sets because of the portrayal standards. Consequently, researchers can conclude that it is possible to generate the building layer of large scale topographic map using multi-oblique images, but additional researches is needed to resolve the problems on differences of the portrayal standards.

• 한국전산유체공학회:학술대회논문집
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• 2008.03a
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• pp.262-267
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• 2008

Numerical investigations were performed with an external-compression inlet with a three-dimensional bump at Mach 2 to scrutinize the geometrical effects of the bump in controlling the interaction of a shock wave with a boundary layer. The inlet was designed for two oblique shock waves and a terminal normal shock wave followed by a subsonic diffuser, with a circular cross-section throughout. The bump-type inlet that replaced the aft ramp of the conventional ramp-type inlet was optimized with respect to the inlet performance parameters as well as compared with the conventional ramp-type inlet. The current numerical simulations showed that a bump-type inlet can provide an improvement in the total pressure recovery downstream of the shock wave/boundary layer interaction over a conventional ramp-type inlet.