• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.97.1-97.1
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• 2012

Porous ceramics are widely used for applications such as catalysis supports, gas distributors and filters such as DPF. For these purpose, it is important to have proper porosity controlling pore structure while maintaining mechanical and thermal properties. In this work, we have prepared the porous ceramic structures made of reaction bonded silicon nitride with hierarchical pore structures. Uni-directionally aligned pore channels, which are mostly filled with ${\beta}$-Si3N4 whiskers, were achieved by an ice-templating method. The structures of the pore channels and the walls are controllable by the processing conditions, such as solid concentration, freezing rate of the slurry, and additives. We have investigated and characterized the influences of the conditions on the microstructures and the properties, such as porosity, pore size distribution, lamellar thickness, wavelength, and orientations. The compressive strength test and flow test was performed to determine the structural integrity and air permeability.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.45 no.2
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• pp.249-255
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• 1996

A self-aligned latch-up suppressed IGBT has been proposed and the process method and the device characteristics of the IGBT have been verified by numerical simulation. As the source is laterally diffused through the sidewall of the trench in the middle of the body, the size of the source is small and the doping concentration of the source is lower than that of the p++ body and the emitter efficiency of the parasitic npn transistor is low so that latch-up may be suppressed. No additional mask steps for p++ region, source, and source contact are required so that small sized body can be obtained Latch-u current density higher than 10000 A/cm$^{2}$ have been achieved by adjusting the process conditions.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.358-361
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• 2001

A new photoalignment material PM15CA, poly{N-(phenyl)maleimide-co-3-[4-(pentyloxy) cinnamate]propyl-2-hydroxy-1-methacrylate}, was synthesized and the electro-optical (EO) characteristics in the vertical-aligned (VA) liquid crystal display (LCD) photo-aligned on the photopolymer surface were studied. Excellent voltage-transmittance(V-T) characteristics in the VA-LCD photoaligned with polarized UV exposure of oblique direction on the pohotopolymer surfaces for 1 min can be achieved. The transmittance of the VA-LCD photoaligned on the photopolymer surface decreased with increasing UV exposure time. We suggest that the decrease of transmittance in the VA-LCD photoaligned on the photopolymer surface is attributed to the dissociation of the ester linkage in the photodimerized cinnamate structure with increasing UV exposure time

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.610-615
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• 2003

This experiment has been carried out to find the structure of turbulent boundary layer with instantaneous velocity fields obtained in stream-wall-normal planes using a stereo-PIV (Particle Image Velocimetry) method. And it has been measured perpendicular plane and horizontal plane with hairpin vortex structure by Reynolds number change and made third dimension shape for section of horizontal plane through stereo-PIV. In the outer layer hairpin vortices occur in streamwise-aligned packets that propagate with small velocity dispersion. A streaky structure is composed of counter-rotating vortex. According as y+ increases, streaky structure's interval space decrease, and it shows that hairpin shape of prior research is vertified. The objective of the present research is to gain a better understanding of coherent structures in the outer of wall turbulence by experimentally examining coherent structures.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.5
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• pp.21-28
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• 1999

A new method of making high speed self-aligned ESD (Elevated Source/Drain) MOSFET is proposed. Different from the conventional LDD (Lightly-Doped Drain) structure, the proposed ESD structure needs only one ion implantation step for the source/drain junctions, and makes it possible to modify the depth of the recessed channel by use of dry etching process. This structure alleviates hot-carrier stress by use of removable nitride sidewall spacers. Furthermore, the inverted sidewall spacers are used as a self-aligning mask to solve the self-align problem. Simulation results show that the impact ionization rate ($I_{SUB}/I_{D}$) is reduced and DIBL (Drain Induced Barrier Lowering) characteristics are improved by proper design of the structure parameters such as channel depth and sidewall spacer width. In addition, the use of removable nitride sidewall spacers also enhances hot-carrier characteristics by reducing the peak lateral electric field in the channel.

• 한국컴퓨터산업교육학회:학술대회논문집
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• 2003.11a
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• pp.67-70
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• 2003

In this paper, propose a new structure of MOFET(Metal-Oxide-Semiconductor Field Effect Transistor) which is widely application for semiconductor technologies. Eleminate the latch-up effect caused by closed devices when conpose a electronic circuit using proposed devices. In this device have a completely isolation structure, and advantage of leakage current elimination. Each independent devices are isolated by trench-well and oxide layer of SOI substrate. Using trench gate and self aligned techniques reduces parasitic capacitance between gate and source, drain. In this paper, we proposed the new structure of SOI MOSFET which has completely isolation and contains trench gate electrodes and SOI wafers. It is simulated by MEDICI that is device simulator.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.672-676
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• 2009

Polymide is widely used alignment material of recent commercial LCD panel structure. Generally, polyimide alignment material is classified soluble polyimide type and polyamic acid type with their main bond structure of solution state. specially, compared to polyamic acid alignment layer, soluble polyimide type alignment layer have excellent reliability during long term LCD driving cause of their high imidazation ratio(%), high voltage holding ratio(%) and low ion density. The other side, this type alignment materials has significant DC image stickicng side effect for using in-plane switching mode lcd structure cause of their slow DC discharging property. we applied inorganic salt to usual soluble polyimide type alignment layer and found out this technique had good DC image sticking property without any loss of reliability property in inplane switching LCD cell structure. This approach leads excellent DC image sticking property with maintaining high reliability property this approach confirmed improves an image sticking and a reliability simultaneously from the horizontality aligned LCD mode whose relatively bad image sticking property.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.287-288
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• 2006

Two approaches for the fabrication of tailored powder composites with specially distributed pore-grain structure and chemical composition are investigated. Electrophoretic Deposition (EPD) followed by microwave sintering is employed to obtain functionally graded materials (FGM) by in-situ controlling the deposition bath suspension composition. $Al_2O_3/ZrO_2$ and zeolite FGM are successfully synthesized using this technique. In order to fabricate an aligned porous structure, unidirectional freezing followed by freeze drying and sintering is employed. By controlling the temperature gradient during freezing of powder slurry, a unidirectional ice-ceramic structure is obtained. The frozen specimen is then subjected to freeze drying to sublimate the ice. The obtained capillary-porous ceramic specimen is consolidated by sintering. The sintering of the graded structure is modeled by the continuum theory of sintering.

• International Journal of Advanced Culture Technology
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• v.11 no.1
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• pp.103-109
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• 2023

This study examines the association between ownership structure and labor investment efficiency. Specifically, this study investigates whether owner-manager firms, where managers own a large percentage of shares in the firm, involve in more efficient labor investment. Based on the management entrenchment hypothesis, managers are more likely to make labor investment decisions to maximize their private benefits rather than creating value for shareholders, resulting in lower efficiency in labor investment. On the other hand, according to the incentive alignment hypothesis, managers tend to make labor investment decisions that will improve future firm performance as their interests are aligned with those of shareholders. In this situation, owner-manager firms are expected to have higher efficiency in labor investment. Our empirical results show that owner-manager firms engage in more efficient labor investment, which contributes to long-term firm value. This study provides empirical evidence that firms' labor investment behavior can vary depending on the characteristics of the ownership structure.

• Korean Institute of Interior Design Journal
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• v.18 no.6
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• pp.176-183
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• 2009

This study was intended to define the spatial concept of the boundary structure of the architectural space as well as evaluate the Hyangdan which well represents the features of Korean traditional building in such a way of reviewing the building structure of Korean traditional residential space. The boundary is categorized into visible boundary and invisible boundary which was also functionally classified into the features of isolating, passing, mediating and overlapping. The major elements comprising the boundary structure was analyzed by the characteristic of the pattern so as to define them as the concept of surrounding, duality, hierarchism, continuity and overlapping. Based on such concepts, a boundary structural characteristics of Hyangdan were reevaluated and outlined as follows. The surrounding feature was seen through the outer side of the structure surrounded, two courtyards and eaves, and a duality showing both the closure of main house and openness of detached house was seen through the characteristics of surrounding structure. And the continuous activities toward the inner room and the empty space to link them in a systematic way and repeatedly aligned rooms reveal the overlapping as continuous and transitional space. And finally, an elevated stylobate demonstrates the hierarchical features of the structure.