• Korean Journal of Materials Research
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• v.16 no.2
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• pp.75-79
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• 2006

The effect of ozone and/or ultrasound treatments on the efficiency of slurry removal in post sliced cleaning (PSC) of silicon ingot was studied. Efficiency of slurry removal was evaluated as functions of time, temperature and surfactant with DOE (Design of Experiment) method. Residual slurries were observed on the wafer surface in case of cleaning by ozone or ultrasound separately. However, a clean wafer surface was appeared when cleaned with ozone and ultrasound simultaneously. It has found that cleaning time was the main effect among temperature, time and surfactant. Elevated temperature, addition of surfactant and high ozone concentration helped to accelerate efficient removal of slurry. The improvement of removal efficiency seems to be related to the formation of more active OH radicals. The highly cleaned surface was achieved at 10 wt% ozone, 1 min and 10 vol% surfactant with ultrasound. Application of ozone and ultrasound might be a useful method for PSC process in wafer cleaning.

• Bulletin of the Korean Chemical Society
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• v.28 no.9
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• pp.1545-1548
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• 2007

This paper discusses the racemic and stereoselective synthetic route for novel 4'α -methyl and 6'α -methyl analogues of abacavir. The quaternary carbon at the 4'-position of carbocyclic nucleoside was installed successfully via a Claisen rearrangement. The stereocontrolled construction of a methyl group in the 6'α - position was directed through the Felkin-Anh rule. A Bis-vinyl compound 9 was cyclized successfully using Grubbs' catalyst II to provide a carbocycle nucleus for the target compound. The synthesized compound 15 showed moderate anti-HIV activity (EC50 = 10.67 μM, MT-4 cell lines).

• Bulletin of the Korean Chemical Society
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• v.29 no.5
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• pp.993-997
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• 2008

Two directional ring-closing metathesis (RCM) was applied successfully to the synthesis of 4'-vinylated carbocyclic nucleoside analogues from the trivinyl intermediate 12, which was readily made using a sequential Claisen rearrangement and ring-closing metathesis (RCM) starting from Weinreb amide 5. An antiviral evaluation of the synthesized compounds against various viruses such as HIV, HSV-1, HSV-2 and HCMV revealed that the guanine analogue 20 have moderate anti-HIV activity in the MT-4 cell line ($EC_{50}$ = 10.2 $\mu$ M).

• Proceedings of the KIEE Conference
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• 1999.07a
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• pp.101-104
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• 1999

This paper presents the design of state feedback controller with state observer(dynamic filter) for Electro-Magnetic Suspension System. Also, the gain scheduling technique using state observer is analyzed in the time domain and frequency domain.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1408-1410
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• 2000

The regulation performances needs high control gain in novel output feedback controller but high control gain is decreased relative stability of the total system. Thus, this paper proposed neural network controller(NNC) for output feedback controller. In this scheme, output feedback controller are guarantee global stability and NNC are controller steady-state error and defined optimal control law. And we demonstrated this scheme by simulations.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1411-1413
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• 2000

Distubance of air-gap sensors by rail irregularities are the serious problem deteriorating the performance in the electromagnetic suspension (EMS) systems. Thus, this paper proposes the output feedback controller with discrete kalman filter for the EMS systems. The discrete kalman filter estimate true state value and output feedback controller guarantee stability. The benefit of this scheme are shown by simulation. Therefore air-gap disturbance are rejected successfully.

• Bulletin of the Korean Chemical Society
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• v.31 no.4
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• pp.915-920
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• 2010

A novel 2',4'-dimethyl carbocyclic adenosine 5'-phosphonic acid analogue (20) was prepared using acyclic stereoselective route from commercially available 4-hydroxybutan-2-one (4). To improve cellular permeability and enhance the anti-HCV activity of this phosphonic acid, a 3',5'-cyclic SATE phosphonodiester nucleoside prodrug (22) was prepared. The synthesized phosphonic nucleoside analogues, (20) and (22), were assayed for their ability to inhibit HCV RNA replication in a subgenomic replicon Huh7 cell line.

• Proceedings of the KIEE Conference
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• 2000.11b
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• pp.280-283
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• 2000

In this paper, a fault tolerant control problem is considered for a class of nonlinear system formulated in a gain scheduling form with LMI-based H-inf control technique Key benefits of this proposed scheme are demonstrated in the simulation of an electromagnetic suspension system with actuator and/or sensor failures, and the method is compared with the convensional state-feedback and output-feedback controller. It is clearly observed that the proposed control scheme shows an improved output performance in comparision with convensional methods.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.181-182
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• 2007

This paper presents the system design of high speed linear synchronous machine in the required speed and thrust considering power of inverter. in this paper, the design of manufacturing motor is optimized by characteristics of motor parameters with the variation of coil turns of rotor and stator. And, the dynamic simulation are performed from the (d-q) transformation of the current and voltage and the mechanical dynamic equation composed of the mover mass and damping ratio. Finally, the results of design and analysis are verificated by finite element analysis.

• Proceedings of the Korean Society of Computer Information Conference
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• 2022.01a
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• pp.395-397
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• 2022

대면 수업에서와 유사한 교수자와 학습자, 학습자들 사이의 상호작용을 통하여 지식습득뿐만 아니라 문제해결능력, 창의적 사고력, 협동학습능력을 양성하기 위해 프로그램 개발 수업에 팀 프로젝트 수업을 적용하여 운영하였다. 수업 운영 후 참여 학생들을 대상으로 만족도 설문을 실시하여 비대면 팀 프로젝트 수업에 대한 만족도와 수업에서 만족하는 부분 그리고 불만족한 경우에 그 원인에 대해 조사하고 분석하였다. 연구 결과 분석된 개선 사항을 차년도 수업에 반영함으로써 팀 프로젝트 수업에 대한 학습자들의 만족도를 향상시키는데 연구의 목적을 둔다.