• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2002년도 종합학술발표회 논문집 Vol.12 No.1
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• pp.237-240
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• 2002

In this paper, we designed and implemented the dual band antenna for IMT-2000 and 5.7㎓ WLAN(Wireless Local Area Network). The antenna was designed by using 3D simulations program, HFSS(High Frequency Structure Simulator). The electrical characteristics were measured by using HP 8720C network analyzer and measured maximum S$\sub$11/ was -25㏈, and maximum VSWR(Voltage Standing Wavc Ratio) was 1.26 for all frequency bands of interests in IMT-2000 and 5.7㎓ WLAN. Simulation results for antenna gain at 2㎓ and 5.7㎓ were 1.31㏈i and 4.1㏈i with omni directional radiation pattern. Implemented antenna is compact sized and can be produced in low cost enough for commercialization.

• Journal of Communications and Networks
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• 제13권6호
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• pp.633-638
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• 2011

In this paper, we consider resource allocation with proportional fairness in the downlink orthogonal frequency division multiple access relay networks, in which relay nodes operate in decode-and-forward mode. A joint optimization problem is formulated for relay selection, subcarrier assignment and power allocation. Since the formulated primal problem is nondeterministic polynomial time-complete, we make continuous relaxation and solve the dual problem by Lagrangian dual decomposition method. A near-optimal solution is obtained using Karush-Kuhn-Tucker conditions. Simulation results show that the proposed algorithm provides superior system throughput and much better fairness among users comparing with a heuristic algorithm.

• 한국전기전자재료학회논문지
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• 제21권4호
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• pp.296-299
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• 2008

The effects of radio frequency (RF) source power for decoupled plasma nitridation (DPN) process on the electrical properties and Fowler-Nordheim (FN) stress immunity of the oxynitride gate dielectrics for deep nano-technology devices has been investigated. With increase of RF source power, the threshold voltage (Vth) of a NMOS transistor(TR) decreased and that of a PMOS transistor increased, indicating that the increase of nitrogen incorporation in the oxynitride layer due to higher RF source power induced more positive fixed charges. The improved off-current characteristics and wafer uniformity of PMOS Vth were observed with higher RF source power. FN stress immunity, however, has been degenerated with increasing RF source power, which was attributed to the increased trap sites in the oxynitride layer. With the experimental results, we could optimize the DPN process minimizing the power consumption of a device and satisfying the gate oxide reliability.

• 정보저장시스템학회논문집
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• 제7권1호
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• pp.13-18
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• 2011

As a standard of optical disk drive (ODD) was determined to Blu-ray diks (BD), researches for securing slim drive thickness, high data transfer rate and high capacity have been progressed. The actuator for applying BD is also required to have high performances, such as compatibility, slim thickness and 3-axis motion. In this paper, an asymmetric dual lens actuator is proposed to satisfy abovementioned performances. To design the actuator in a limited space, stress analysis and design of experiment (DOE) are performed to reduce weight of moving part and increase driving force and flexible mode frequency. Consequently, the final model, which is satisfied with specifications, is secured.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2007년도 학술대회
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• pp.432-435
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• 2007

In this paper, a dual band microstrip patch Antenna is designed for RFID Application. The antenna shows a good performance at the frequencies, 900MHz and 2.45GHz for the radiation characteristics and input impedance matching, as well. The reflection factor is lower than -25dB and a good directivity higher than 5dB is achieved for both frequency.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 추계종합학술대회 논문집
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• pp.275-278
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• 1999

In this paper, Dual PFD(Phase Frequency Detector) with improved phase locking time is proposed. The proposed PFD consists of positive and negative edge triggered D flip-flop. In order to confirm the characteristics of proposed PFD, HSPICE simulations are performed using a 0.25${\mu}{\textrm}{m}$ CMOS process. As a result of simulations, the proposed PFD has a characteristic of fast phase locking time with dead zone free.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 추계학술대회논문집
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• pp.1067-1072
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• 2003

Generally dual mass flywheel(DMF) is used as a solution to reduce noise and vibration of power train system and to improve the comfortability of passenger car. In this paper, design concept of new DMF model, analytical/numerical model, test procedure and tuning results are presented. Design parameters are studied by some numerical methods and tests. As the result, we can find more efficient model of DMF and reduce vibration level in power train system.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 하계학술대회 논문집 B
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• pp.660-662
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• 1993

We have numerically analyzed by using the Beam Propagation Method the Dual-channel directional couplers, which peforms a number of useful fuctions in thin-films devices, including power division, modulation, switching, frequency selection, and polarization selection. We also use the effective index method to reduce one dimension.

• Journal of electromagnetic engineering and science
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• 제19권1호
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• pp.37-41
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• 2019

A stack-ring configuration is proposed for designing a dual-band circularly polarized (CP) antenna. Each ring generates different resonant frequencies. A good CP performance at both resonant frequencies is achieved by adjusting the relative distance between the two rings. The two operating bands are separated with a small frequency ratio of 1.07. Measured results show that radiation patterns with good CP characteristics are obtained at the two resonant frequencies.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2007년도 학술대회
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• pp.411-414
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• 2007

In this paper, we studied on characteristic improvement of Balun-BPF using dual-mode ring resonators. The simulated Balun-BPF shows bandwidth of 150MHz at center frequency of 2.45GHz, 4-pole characteristic, return loss of 15dB and symmetrical out-put characteristic.