• 융합신호처리학회 학술대회논문집
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• 한국신호처리시스템학회 2000년도 하계종합학술대회논문집
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• pp.357-360
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• 2000

In this paper, we want to implement a noise canceller by using FIR filter on DSP(Digital Signal Processor). The FIR filter was designed by Blackman window together with desired band width and center frequency. We adopt Motorola DSP56002 and Crystal CS4215 (A/D and D/A converter) for our purpose. we generate input sinusoidal signals and noises by differential equations and pseudo random sequences on DSP also. The input signal including sinusoidal and noise passes through the FIR filter. The FIR filer output is a sinusoidal signal with noise reduced.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2020년도 전력전자학술대회
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• pp.459-460
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• 2020

The design of a low distortion class E amplifier with a frequency of 6.78MHz for a wireless power transfer is presented. The amplifier with a differential out is designed to reduce the harmonics of the output current. The harmonic characteristics of various types of the class E amplifiers are compared through the simulation study.

• 전기학회논문지
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• 제57권6호
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• pp.915-923
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• 2008

This paper focuses on optimal tuning of nonlinear parameters of a dual-input power system stabilizer(dual-input PSS), which can improve the system damping performance immediately following a large disturbance. Until recently, various PSS models have developed to bring stability and reliability to power systems, and some of these models are used in industry applications. However, due to non-smooth nonlinearities from the interaction between linear parameters(gains and time constants of linear controllers) and nonlinear parameters(saturation output limits), the output limit parameters cannot be determined by the conventional tuning methods based on linear analysis. Only ad hoc tuning procedures('trial and error' approach) have been used. Therefore, the steepest descent method is applied to implement the optimal tuning of the nonlinear parameters of the dual-input PSS. The gradient required in this optimization technique can be computed from trajectory sensitivities in hybrid system modeling with the differential-algebraic-impulsive-switched(DAIS) structure. The optimal output limits of the dual-input PSS are evaluated by time-domain simulation in both a single machine infinite bus(SMIB) system and a multi-machine power system in comparison with those of a single-input PSS.

• Journal of electromagnetic engineering and science
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• 제14권1호
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• pp.1-8
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• 2014

A differential-cascode CMOS power amplifier (PA) with a supply modulator for envelope tracking (ET) has been implemented by 0.18 ${\mu}m$ RF CMOS technology. The loss at the output is minimized by implementing the output transformer on a FR-4 printed circuit board (PCB). The CMOS PA utilizes the $2^{nd}$ harmonic short at the input to enhance the linearity. The measurement was done by the 10MHz bandwidth 16QAM 6.88 dB peak-to-average power ratio long-term evolution (LTE) signal at 1.85 GHz. The ET operation of the CMOS PA with the supply modulator enhances the power-added efficiency (PAE) by 2.5, to 10% over the stand-alone CMOS PA for the LTE signal. The ET PA achieves a PAE of 36.5% and an $ACLR_{E-UTRA}$ of -32.7 dBc at an average output power of 27 dBm.

• 대한전기학회논문지:시스템및제어부문D
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• 제55권12호
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• pp.550-557
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• 2006

This paper proposes a dry-type surface myoelectric sensor for the myoelectric hand prosthesis. The designed surface myoelectric sensor is composed of skin interface and processing circuits. The skin interface has one reference and two input electrodes, and the reference electrode is located in the center of two input electrodes. In this paper is proposed two types of sensors with the circle- and bar-shaped reference electrode, but all input electrodes are the bar-shaped. The metal material of the electrodes is the stainless steel (SUS440) that endures sweat and wet conditions. Considering the conduction velocity and the median frequency of the myoelectric signal, the inter-electrode distance (IED) between two input electrodes as 18mm, 20mm, and 22mm is selected. The signal processing circuit consists of a differential amplifier with a band pass filter, a band rejection filter for rejecting 60Hz power-line noise, amplifiers, and a mean absolute value(MAV) circuit. Using SUS440, six prototype skin interface with different reference electrode shape and IED is fabricated, and their output characteristics are evaluated by output signal obtained from the forearm of a healthy subject. The experimental results show that the skin interface with parallel bar shape and the 18mm IED has a good output characteristics. The fabricated dry-type surface myoelectric sensor is evaluated for the upper-limb amputee.

• ETRI Journal
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• 제42권5호
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• pp.773-780
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• 2020

A 40 nm complementary metal oxide semiconductor carrier-aggregated drive amplifier with high linearity is presented for sub-GHz Internet of Things applications. The proposed drive amplifier consists of two high linear amplifiers, which are composed of five differential cascode cells. Carrier aggregation can be achieved by switching on both the driver amplifiers simultaneously and combining the two independent signals in the current mode. The common gate bias of the cascode cells is selected to maximize the output 1 dB compression point (P1dB) to support high-linear wideband applications, and is used for the local supply voltage of digital circuitry for gain control. The proposed circuit achieved an output P1dB of 10.7 dBm with over 22.8 dBm of output 3rd-order intercept point up to 0.9 GHz and demonstrated a 55 dBc adjacent channel leakage ratio (ACLR) for the 802.11af with -5 dBm channel power. To the best of our knowledge, this is the first demonstration of the wideband carrier-aggregated drive amplifier that achieves the highest ACLR performance.

• 정보보호학회논문지
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• 제29권6호
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• pp.1259-1270
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• 2019

블록 암호를 설계할 때, 설계자는 주로 차분 특성 확률의 상한을 이용하여 라운드 수를 결정한다. 라운드 수는 블록 암호의 성능에 영향을 미치므로, 더 적은 라운드를 갖기 위해 차분 특성 확률의 상한을 정밀하게 계산하는 것이 중요하다. 이전까지의 활성 S-box의 최소 개수를 탐색하는 방법들은 비선형 연산과 선형 연산을 각각 제약식으로 구성하여 차분 특성 확률의 상한을 계산하였다. 하지만 선형 연산이 비선형 연산에 의존적으로 선택되는 BOGI 설계전략(Bad-Output Good-Input Design Strategy)의 경우 이전 탐색방법으로 구한 상한은 정밀하지 않을 수 있다. 본 논문에서는 BOGI 전략의 성질을 이용하여 기존의 방법보다 더 정밀한 차분 특성 확률의 상한을 구하는 새로운 방법을 제안한다. 그리고 이 방법을 이용하여 구한 상한의 타당성을 수학적으로 증명한다. 제안한 방법을 BOGI가 사용된 GIFT-64와 GIFT-128에 각각 적용하여 9라운드까지 차분 특성 확률의 상한을 탐색하였다. GIFT-64의 7라운드와 GIFT-128의 9라운드에 대해 기존의 방법을 적용하면 차분 특성 확률의 상한이 각각 2^-18.395와 2^-26.885이었으나, 제안한 방법을 적용하면 각각 2^-19.81과 2^-28.3으로 더 정밀하게 계산된다.

• 유통과학연구
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• 제17권11호
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• pp.81-92
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• 2019

Purpose: The salesperson, the core of the operating activities, plays the role of connecting the inside and outside of the company, representing the company to the consumer and identifying and responding to the customer's needs. The department store industry is the most representative retail industry in South Korea, and competition among its peer group and industry is intensifying, requiring differentiated service sales activities and performance from its employees. This study divided the sales force system into activity control(process-oriented control) and output control(performance-oriented control) and verified the differential impact on the job attitude of the salesperson (e.g., job satisfaction and burn-out), respectively. In addition, the effect of job satisfaction and burn-out of the salesperson on the job performance were checked. Research design, data, and methodology: The survey was conducted on 200 sales people working at five branch stores of Hyundai department store in Seoul, and 194 of them were analyzed. The reliability and validity of the variables were analyzed and hypotheses were verified through the SEM. Results: Results have shown that activity control has a greater impact on burn-out compared to output control, and output control has a greater impact on job satisfaction compared to activity control. It has been shown that the salesperson's burn-out does not affect sales performance, but that job satisfaction has a positive effect on sales performance. Conclusions: This study examines the effect of sales force management system such as activity control and output control, on the job attitude and sales performance in department stores. According to the results of this research, each of two control systems have a discriminatory effect on the job attitude variables. For the sales managers of department store, it is recommended to increase the efficiency of sales management by increasing the use of outcome control compared to activity control.

• Smart Structures and Systems
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• 제9권3호
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• pp.231-251
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• 2012

The stochastic optimal control for a piezoelectric spherically symmetric shell subjected to stochastic boundary perturbations is constructed, analyzed and evaluated. The stochastic optimal control problem on the boundary stress output reduction of the piezoelectric shell subjected to stochastic boundary displacement perturbations is presented. The electric potential integral as a function of displacement is obtained to convert the differential equations for the piezoelectric shell with electrical and mechanical coupling into the equation only for displacement. The displacement transformation is constructed to convert the stochastic boundary conditions into homogeneous ones, and the transformed displacement is expanded in space to convert further the partial differential equation for displacement into ordinary differential equations by using the Galerkin method. Then the stochastic optimal control problem of the piezoelectric shell in partial differential equations is transformed into that of the multi-degree-of-freedom system. The optimal control law for electric potential is determined according to the stochastic dynamical programming principle. The frequency-response function matrix, power spectral density matrix and correlation function matrix of the controlled system response are derived based on the theory of random vibration. The expressions of mean-square stress, displacement and electric potential of the controlled piezoelectric shell are finally obtained to evaluate the control effectiveness. Numerical results are given to illustrate the high relative reduction in the root-mean-square boundary stress of the piezoelectric shell subjected to stochastic boundary displacement perturbations by the optimal electric potential control.

• 전자공학회논문지
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• 제50권4호
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• pp.9-16
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• 2013

LTE (long term evolution) 및 LTE-A (LTE-Advanced) 시스템에서는 폐회로 기반의 다중 안테나 기술이 적용되었으며, 최대 비 전송 방식 (maximum ratio transmission, MRT) 보다 성능은 감소되지만, 동 이득 (equal gain) 특성을 유지할 수 있는 동 이득 전송 (equal gain transmission, EGT) 코드북을 채택하고 있다. 본 논문에서는 LTE 및 LTE-A 시스템에서 사용되는 코드북보다 성능을 향상시킬 수 있는 차분 코드북을 제안한다. 특히 동 이득 특성을 그대로 유지하면서 LTE 시스템의 코드북 요구조건을 모두 만족시키는 코드북을 제안한다. 코드북을 구성하는 코드워드들의 인자들 (elements)이 8-PSK(phase-shift keying) 성운 (constellation) 만을 사용하므로, 선부호화 및 복호 시 계산량이 낮아지는 LTE 코드북의 장점을 그대로 유지할 수 있다. 동 이득 성질은 특히 상향 링크에서 첨두 전력 대 평균 전력비 (PAPR)에 상당한 영향을 미치므로 매우 중요하다. 본 논문에서는 각 송신 안테나에 동 이득을 유지하는 성질을 이용한 새로운 차분 코드북을 제안하고, 동작원리를 회전 로크 구조로 설명한다. 컴퓨터 시뮬레이션을 통한 성능 분석에서, 동일한 피드백 비트 수를 갖는 같은 크기의 코드북에서 제안하는 차분 코드북은 기존 LTE 코드북보다 최소 0.9dB 성능 향상을 보인다.