• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.796-799
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• 2006

We studied the nematic liquid crystal (NLC) alignment capability by the Ion beam (IB) alignment method on a NDLC (Nitrogen doped Diamond Like Carbon) as a C:H thin film, and investigated electro-optical (EO) performances of the IB aligned In plane switching (IPS) cell with NDLC surface. A good LC alignment by IB exposure on a NDLC surface was achieved. Monodomain alignment of the IB aligned IPS cell can be observed. The good electro-optical characteristics of the IB aligned IPS cell was observed with oblique IB exposure on the NDLC as a-C:H thin film for 1min.

• Transactions on Electrical and Electronic Materials
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• v.4 no.2
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• pp.5-9
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• 2003

The liquid crystal (LC) aligning capabilities by the washing processes after rubbing on the two kinds of the rubbed polyimide (Pl) surface were studied. The polar anchoring energy of 4-n-pentyl-4'-cyanobiphenyl (5CB) increased with the rubbing strength RS on the two kinds of the rubbed PI surface. The polar anchoring energy of 5CB on the rubbed PI surface with alkyl side chains is larger than the rubbed PI surface with CONH moiety. Also, the surface ordering of 5CB on the rubbed PI surface with alkyl side chains is larger than the rubbed PI surface with CONH moiety. Therefore, the surface ordering of 5CB strongly depends on the polymers and washing process.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.05a
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• pp.94-97
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• 2004

In this paper, we investigate fringe-field switching (FFS) mode cell by the ion beam (IB) alignment method on the a-C:H thin film, to analyze electro-optical characteristics in this cell. We studied on the suitable inorganic thin film for fringe-field switching (FFS) cell and the aligning capabilities of nematic liquid crystal (NLC) using the new alignment material of a-C:H thin film An excellent voltage-transmittance (V-T) and response time curve of the IB-aligned FFS-LCD was observed with oblique IB exposure on the DLC thin films. Also, AC V-T hysteresis characteristics of the IB-aligned FFS-LCD with IB exposure on the DLC thin films is almost the same as that of the rubbing-aligned FFS cell on a polyimide (PI) surface.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.330-330
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• 2008

It is widely investigated to liquid crystal (LC) alignment using non-contact alignment method such as ion-beam (IB) irradiation, UV alignment, and oblique deposition. Because conventional rubbing method has some drawbacks. These include defects from dust and electrostatic charges and rubbing scratch during rubbing process. In addition, rubbing method needs additional process to remove these defects. Therefore rubbing-free methods like ion-beam irradiation are strongly required. We studied LC alignment effect on poly imide surface by IB irradiation and electro-optical (EO) characteristics of twisted nematic liquid crystal display (TN-LCD). In this experiment, a good uniform alignment of the nematic liquid crystal (NLC) with the ion-beam exposure on the polyimide (PI) (SE-150 from Nissan Chemical) surface was observed. We also achieved low pretilt angle as a function of ion-beam irradiation intensity. In addition, it can be obtained the good EO properties of the IB-aligned TN-LCD on PI surface. Some other experiments results and discussion will be included in the poster.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.12
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• pp.1640-1648
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• 2014

This paper proposes a switching frequency reduction method for MMC (Modular Multilevel Converter) utilizing redundancy operation of sub-module, which can offer reduction of voltage harmonics and switching loss. The feasibility of proposed method was verified through computer simulations with PSCAD/EMTDC software. Based on simulation analysis, a hardware scaled-model of 10kVA, DC-1000V MMC was designed and manufactured in the lab. Various experiments were conducted to verify the feasibility of proposed method in the actual hardware system. The hardware scaled-model can be effectively utilized for analyzing the performance of MMC according to the modulation scheme and redundancy operation.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.12
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• pp.5185-5188
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• 2016

Objective: Targeted-drug-delivery based lipid nanoparticles has emerged as a new and effective approach in cancer chemotherapy. Here, we investigated the ability of folate-modified nanostructured lipid carriers (NLCs) to enhance letrozol (LTZ) efficacy in MCF-7 breast cancer cells. Methods: New formulations were evaluated regarding to particle size and scanning electron microscope (SEM) features. Anti-proliferative effects of LTZ loaded nanoparticles were examined by MTT assay. To understand molecular mechanisms of apoptosis and cell cycle progression, flow cytometric assays were applied. Results: Optimum size of nanoparticles was obtained in mean average of $98{\pm}7nm$ with a poly dispersity index (PDI) of 0.165. The IC50 value was achieved for LTZ was $2.2{\pm}0.2{\mu}M$. Folate-NLC-LTZ increased the percentage of apoptotic cells from 24.6% to 42.2% compared LTZ alone (p<0.05). Furthermore, LTZ loaded folate targeted NLCs caused marked accumulation of cells in the subG1 phase. Conclusion: Taken together, our results concluded that folate targeted LTZ can be considered as potential delivery system which may overcome limitations of clinical application of LTZ and improve drug efficacy in tumor tissue.

• Journal of Power Electronics
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• v.16 no.5
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• pp.1706-1715
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• 2016

In this paper, a single phase modified switched-diode topology for both symmetrical and asymmetrical cascaded multilevel inverters is presented. It consists of a Modified Switched-Diode Unit (MSDU) and a Twin Source Two Switch Unit (TSTSU) to produce distinct positive voltage levels according to the operating modes. An additional H-bridge synthesizes a voltage waveform, where the voltage levels of either polarity have less Total Harmonic Distortion (THD). Higher-level inverters can be built by cascading MSDUs. A comparative analysis is done with other topologies. The proposed topology results in reductions in the number of power switches, losses, installation area, voltage stress and converter cost. The Nearest Level Control (NLC) technique is employed to generate the gating signals for the power switches. To verify the performance of the proposed structure, simulation results are carried out by a PSIM under both steady state and dynamic conditions. Experimental results are presented to validate the simulation results.

• The Transactions of the Korean Institute of Power Electronics
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• v.22 no.4
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• pp.285-296
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• 2017

This paper proposes an improved modulation scheme for the medium voltage modular multi-level converter (MMC), which operates in the nearest level control and applies in the medium voltage direct current (MVDC) system. In the proposed modulation scheme, the offset (neutral-to-zero output) voltage is adjusted, with the phase voltage magnitude, thereby maintaining a constant value with N+1 level in the controllable modulation index (MI) range. In order to confirm the proposed scheme's validity, computer simulations for the 22.9 kV - 25 MVA MMC were performed with PSCAD/EMTDC, as well as hardware experiments for the 380 V - 10 kVA MMC. The proposed modulation scheme offers to build a constant pole voltage regardless of the MI value, and to build a phase voltage with improved total harmonic distortion (THD).

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.460-463
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• 2005

We studied the nematic liquid crystal (NLC) alignment capability by the Ultraviolet (UV) alignment method on a a-C:H thin -film , and investigated electro-optical performances of the UV aligned twisted nematic (TN)- liquid crystal display (LCD) with the UV exposure on a-C:H thin film surface. A good LC alignment by UV irradiation on a a-C:H thin -film surface was achieved. Monodomain alignment of the UV aligned TN-LCD can be observed. The good electro-optical (EO)characteristics of the UV aligned TN-LCD was observed with oblique UV exposure on the a-C:H thin film surface for 1min.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.468-470
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• 2005

We studied the nematic liquid crystal (NLC) aligning capabilities using the new alignment material of the SiC (Silicon Carbide) thin film. The SiC thin film exhibits good chemical and thermal stability. The good thermal and chemical stability makes SiC an attractive candidate for electronic applications. A vertical alignment of nematic liquid crystal by ion beam exposure on the SiC thin film surface was achieved. The about $87^{\circ}$ of stable pretilt angle was achieved at the range from $30^{\circ}$ to $45^{\circ}$ of incident angle. The good LC alignment is main-tained by the ion beam alignment method on the SiC thin film surface at high annealing temperatures up to 300.