• 대한의용생체공학회:의공학회지
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• 제45권2호
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• pp.101-107
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• 2024

Steady-state visual evoked potential-based brain-computer interface (SSVEP-BCI) is one of the promising systems that can serve as an alternative input device due to its stable and fast performance. However, one of the major bottlenecks is that some individuals exhibit no or very low SSVEP responses to flickering stimulation, known as SSVEP illiteracy, resulting in low performance on SSVEP-BCIs. However, a lengthy duration is required to enhance multiple SSVEP responses using traditional single-frequency transcranial alternating current stimulation (tACS). This research proposes a novel approach using dual-frequency tACS (df-tACS) to potentially enhance SSVEP by targeting the two frequencies with the lowest signal-to-noise ratio (SNR) for each participant. Seven participants (five males, average age: 24.42) were exposed to flickering checkerboard stimuli at six frequencies to determine the weakest SNR frequencies. These frequencies were then simultaneously stimulated using df-tACS for 20 minutes, and the experiment was repeated to evaluate changes in SSVEP responses. The results showed that df-tACS effectively enhances the SNR at each targeted frequency, suggesting it can selectively improve target frequency responses. The study supports df-tACS as a more efficient solution for SSVEP illiteracy, proposing further exploration into multi-frequency tACS that could stimulate more than two frequencies, thereby expanding the potential of SSVEP-BCIs.

• 한국정보전자통신기술학회논문지
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• 제6권1호
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• pp.23-28
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• 2013

본 논문에서는 모바일 환경에서 dual microphone을 이용하여 배경 잡음을 효율적으로 제거하는 방법을 제안한다. 참조 마이크와 주 입력 마이크로부터 측정된 신호를 각각 FDAF의 참조신호와 주 입력 신호로 하여 잡음 제거를 수행한 뒤에 MMSE-LSA를 이용하여 잔여 잡음 및 배경 잡음을 추정하여 제거 한다. 이때 일관성 있는 잡음 제거 성능을 위해 두 마이크 신호의 PLD를 이용한 VAD 결과를 사용한다.

• 반도체디스플레이기술학회지
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• 제2권2호
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• pp.31-37
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• 2003

This paper presents a measurement system of mechanical property using dual servo system. There are many kinds of method to measure material properties such as tensile test, indention and bending test. It is highly required to measure the properties of nano-sized material and structure. However, It is need more accurate measurement system, more stable and frequency response than conventional test. In this paper, we designed the dual servo system for a measuring instrument The dual servo system consisting of a coarse stage and a fine motion stage with VCM and PZT is proposed. Mechanical mechanism is designed with the leaf spring type of flexure hinge joint. Lead compensator is applied to this control system, and is designed by PQ method.

• 가정과삶의질연구
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• 제9권2호
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• pp.323-343
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• 1991

The purpose of this study is to examine the relationship among stressor(role conflict), coping strategy, and psychological well-being toward dual-career wives. For this purpose data were collected form 117 dual -career wives. The statistical methods used for data analysis were frequency distribution. percentile, Pearson's correlation and multiple regression. The results were as follows; 1)The general tendency of the stressor level of dual-career wives was slightly over the mid-point scores, 2.5 and the level of psychological well-being was relatively high. Also, the degree to which dual-career wives used coping strategies was relatively high. 2)Role conflicts were negatively related to psychological well-being. 3)Coping strategies were positively related to psychological well-being. 4)The degree of the negative influence which role conflicts had on psychological well-being was lower int he group using a high degree of coping strategies than in the group using a low degree of coping strategies.

• 전력전자학회논문지
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• 제17권2호
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• pp.142-149
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• 2012

The independently regulated dual-output LLC resonant converter using only one power stage and one control IC is proposed in this paper. The conventional dual-output LLC resonant converter requires the extra non-isolated DC/DC converter to obtain the tightly regulated slave output voltage, which results in the low power conversion efficiency and high production costs. On the other hand, since the proposed converter controls the master and slave output voltages by pulse width modulation(PWM) and pulse frequency modulation(PFM), it can achieve tightly regulated dual output voltages without the additional non-isolated DC/DC converter. Therefore, it features a high efficiency and low cost. To confirm the validity of the proposed converter, theoretical analysis and experimental results from a 40W LED driver prototype are presented.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1998년도 춘계학술대회 논문집
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• pp.41-44
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• 1998

Dual mode resonators were fabricated using high temperature superconductor. The deposited material was $Y_1Ba_2Cu_3O_{7-x}$(YBCO) on MgO(100) substrate using pulsed laser deposition. Dual mode resonators were patterned by standard photolithography process and wet etching. At the back-side of the substrate, the ground plane with the metal layer of Ti and Ag was fabricated. The transition temperatures of YBCO films were 85-88 K, and network analyzer was used for testing the performance of the resonators. The input/output feedline angles of each resonator were $60^{\circ}$and $100^{\circ}$. The resonant frequency of resonators was 10 GHz. In this paper, dual mode resonator was fabricated for the application of satellite communication.

• 한국전자파학회논문지
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• 제18권6호
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• pp.648-655
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• 2007

본 논문에서는 유도결합을 이용한 RFID 시스템에서 주변의 RF 잡음의 영향을 감소할 수 있는 이중 코일 안테나를 새로이 제안하고 실험하였다. 이중 코일 안테나는 동일한 구조의 코일 2개가 직렬로 연결되어 있으며 두 코일에 유도되는 잡음 전압의 크기가 같고 극성이 반대가 되어 서로 상쇄되도록 고안된 구조이다. RFID 리더에 이중 코일 안테나를 사용한 경우에 단일 코일 안테나에 비하여 RF 유도 잡음이 약 15 dB 감소하였다.

• 전기학회논문지
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• 제62권1호
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• pp.127-132
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• 2013

In this paper, we design the physical layer of Guardian modem for wireless public networks. The physical layer is composed of a dual-band RF (Radio Frequency) transceiver and a baseband-processor with quasi-orthogonal codes. The 2.4/5GHz dual-band RF transceiver can overcome the communication difficulty of dense 2.4GHz band for wireless public environment. Also the quasi-orthogonal code can reduce the required ASIC (Application Specific Integrated Circuit) design area. Finally, we analyze the performance of the developed system in viewpoint of data rate, BER (Bit Error Rate), PER (Packet Error Rate). Moreover we verify the performance of the dual-band RF communication.

• 전력전자학회논문지
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• 제20권2호
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• pp.144-151
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• 2015

The present study proposes a method for modeling a SONAR transducer with dual resonance. The Butterworth van-Dyke (BVD) model, a conventional SONAR transducer modeling method, can model only one resonance point. Hence, to address its disadvantage and to model the dual resonance, a dual resonance BVD model consisting of two serial BVD models is proposed. The two BVD models are connected in a series, and each simulate resonance at low frequency and high frequency, which allows the modeling of two resonance points. Eight elements compose the equivalent circuit by connecting the BVD models in a series, which is twice as great as that of the existing BVD model. The element value of the dual resonance BVD model is extracted by using the particle swarm optimization method. Analysis was also performed to identify the effects of changes in the value of elements that compose the equivalent circuit on the impedance characteristics of the equivalent circuit through simulation in which element values varied.

• 한국통신학회논문지
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• 제32권10A호
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• pp.1015-1022
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• 2007

본 논문에서는 UHF(Ultra High Frequency)와 MW(Micro Wave) 대역의 RFID 리더 시스템을 위한 디지털 코덱을 제안하였다. 현재 RFID 시스템은 하나의 프로토콜만을 지원하는 것이 대부분이다. 하지만, 현재 제정되어 있는 표준은 5개의 주파수 대역마다 각각 하나씩 제정되어 있고, 전 세계적으로 가장 널리 쓰이고 있는 UHF 대역의 경우에는 A,B,C 타입이 있으며 향후 더 많은 표준이 제정될 것이다. 또한 앞으로 모바일 RFID 시스템의 관심이 고조되면서 하나 이상의 프로토콜을 지원하는 RFID 시스템의 필요성은 더욱 더 증가할 것이다. 따라서 본 논문에서는 UHF 대역과 MW대역의 dual-band RFID 시스템을 위한 디지털 코덱을 제안하였다. UHF 대역은 EPC 클래스 1 제너레이션 2(EPC Class1 Generation2)표준인 18000-6C 와 MW 대역의 표준인 18000-4 표준을 기반으로 시스템을 구현하였다. 설계된 회로는 알테라사의 쿼터스II 를 이용하여 합성 하였다. 목적 디바이스는 Altera 사의 CycloneII 계열인 EP2C20Q240C8이다. 주 클럭 주파수는 19.2MHz 로 설정하였으며 합성 시 사용된 FPGA의 소자(element)는 18,752개이다.