• International journal of advanced smart convergence
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• 제12권4호
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• pp.426-433
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• 2023

The purpose of this study was to investigate the muscle activity of the lower extremity during driver swing in three-foot positions (Feet Open Stance, Feet Straight Stance, Lead Foot Open Stance). The electromyograms of gastrocnemius, tibialis anterior, and vastus lateralis during swing were measured and analyzed in three sections (take away - back swing, back swing - down swing, and down swing - follow swing). There was no significant difference in muscle activity according to foot position. Muscle activity according to phase was significantly higher in right gastrocnemius and tibialis anterior, and the left and right vastus lateralis in down swing - follow swing. In conclusion, the difference in muscle activity according to foot position is insignificant, and it is considered that the muscle activity to maintain the balance of the body increases toward the end of swing.

• 한국정보통신학회논문지
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• 제7권2호
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• pp.194-200
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• 2003

본 논문에서는 주파수 도약 대역확산시스템에서 널리 적용되는 FSK복조기를 설계하고 실험 결과를 분석하였다. FSK 복조회로에 있어서 가장 중요한 부분인 ADPLL의 성능을 소프트웨어를 이용하여 분석하였다. 이 분석을 토대로 Altera사에서 제공하는 Maxplus-II 툴을 이용하여 각 구성 회로를 설계하였으며 EPM7064SLC44-10 chip으로 집적화 하였다. 시뮬레이션 결과와 구현된 회로의 특성을 비교 분석하였다. 결과에 있어서 PLL의 시상수는 약 2${\mu}\textrm{s}$의 차이가 발생하였다. 이 차이는 FSK복조회로에 있어서는 큰 영향을 주지 않는다. 실험결과를 보면 FSK 변조된 신호는 기준 신호와 위상 차가 180$^{\circ}$인 경우에도 설계된 회로에 의해 잘 복조 됨을 관찰할 수 있었다.

• 센서학회지
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• 제17권4호
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• pp.289-294
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• 2008

The purpose of this study is to materialize the viscosity sensor by using the SH-SAW sensor of which the center frequency is operated at higher than 50 MHz. In order to measure the viscosity, SAW sensor of which the center frequency is operated at 100 MHz is developed. By using the developed sensor, phase shift, delay time, insertion loss, and frequency variation are measured at different viscosity. The result shows that the phase shift difference between the viscosity variations is such that the difference between the distilled water and the 100 % glycerol solution is approximately $45^{\circ}$, the change of the insertion loss is approximately 9 dB, and the difference of frequency variation is approximately 5.9 MHz. Therefore, it is shown that viscosity of unknown solution can be measured with the surface acoustic wave sensor.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제55권5호
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• pp.250-257
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• 2006

It is well known that Grain-oriented electrical steel sheets have two dimensional magnetic properties according to the direction of exciting field such as non-linear phase difference between magnetic flux density and magnetic field intensity vectors, different iron loss and permeability even when an alternating magnetic field is applied. The measurement and application of the two dimensional magnetic properties of the Grain-oriented electrical steel sheets, therefore, are very important for the design and precise performance analysis of electric machines made of them. As the direction of exciting field changes, in this paper, the two dimensional magnetic properties of a Grain-oriented electrical steel sheet, i.e., non-linear B-H curves, phase difference between B and H, and iron loss characteristics, are measured using SST(Single Sheet Tester) which has two axes excitation. The measured results are presented in two ways: using $(B,\theta_B)$ method and using hysteresis loops along rolling and transverse directions, respectively.

• Tribology and Lubricants
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• 제31권3호
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• pp.102-108
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• 2015

In this research, we experimentally investigated the sealing performance of elastomeric rotary lip seals for washing machines. In general, NBR is used as a material for elastomeric rotary lip seals in washing machines, but the mixing formula of the rubber material can affect the sealing performance. In this study, we manufactured rotary lip seals using three kinds of NBRs with a different mixing formula, and examined the sealing performance using an acceleration test mode. The results of an SEM investigation into the surfaces of three kinds of specimens showed a much smaller wear volume and better sealing performance for the specimens with smaller particle sizes of mixing composition than for the specimen with the larger. Repeated deformation and recovery by the shaft-to-seal eccentricity on rotation were shown to cause a phase difference in the rubber material, and we measured the recovery ratio to find the influence of this phase difference on the sealing performance. As another method for checking the phase difference, we also measured tan ä, and a lower tan ä was revealed as the recovery ratio increased for each specimen. Specimens with a higher recovery ratio (lower tan ä) were shown to have a better sealing performance. Consequently, specimens with a smaller particle size in the mixing composition had a better sealing performance because they show a higher recovery ratio.

• 한국컴퓨터정보학회논문지
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• 제13권6호
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• pp.211-216
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• 2008

휴대전화를 통해서 양질의 DMB(Digital Multimedia Broadcasting) 서비스를 받기 위하여 지하나 건물사이 음영지역을 제거하기 의한 갭필러(Gap filler) 안테나가 필요하다. 동축 급전선과 4개의 임피던스 정합회로를 필요로 하는 종래의 방식에 비하여 PCB의 피딩 라인에 의한 위상 차이를 이용한 Quadrifilar Helical Antenna(QHA)를 설계하고 제작한다. MicroWave Studio를 이용한 시뮬레이션을 통하여 기존 방식의 QHA에 비해 안테나의 크기와 직경이 안테나 특성에 많은 영향을 주는 것을 파악하여 QHA 제작에 활용하였다. 시뮬레이션을 통한 설계 데이터를 근거로 별도의 임피던스 정합회로가 필요 없는 QHA를 제작하여, 전기적 특성을 측정한 결과 설계치와 유사한 특성을 얻었다.

• Journal of information and communication convergence engineering
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• 제11권3호
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• pp.147-152
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• 2013

A novel balun being the structure of a Wilkinson power divider is suggested and fabricated. One of the power dividing paths in the suggested balun uses a conventional ${\lambda}/4$ transmission line for $-90^{\circ}$ phase shifting, and the other path uses a composite right/left-handed -${\lambda}/4$ transmission line for $+90^{\circ}$ phase shifting with four series capacitors and three parallel inductors. In addition, the suggested balun uses two $50-{\Omega}$ resistors and a conventional $50-{\Omega}$ transmission line of ${\lambda}/2$ electrical length between the two output ports, achieving good isolation and reflection values of two balanced ports. The suggested balun is simulated by the advanced design system simulation program and fabricated on TLX-9 20-mil substrate. The fabricated balun has a very good values of $S_{11}$ = -27.46 dB, $S_{21}$ = -3.40 dB, and $S_{31}$ = -3.28 dB, a phase difference of $-179.5^{\circ}$, a magnitude difference of 0.12 dB, and a delay difference of 0.1 ns, with $S_{22}$ = -36.28 dB, $S_{33}$ = -27.19 dB, and $S_{32}$ = -25.2 dB at 1 GHz, respectively.

• Journal of Electrical Engineering and Technology
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• 제11권1호
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• pp.157-166
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• 2016

In this paper, a new sag and peak voltage detector is proposed for a single-phase inverter using delta square operation. The conventional sag detector is from a single-phase digital phase-locked loop (DPLL) that is based on d-q transformations using an all-pass filter (APF). The d-q transformation is typically used in the three-phase coordinate system. The APF generates a virtual q-axis voltage component with a 90° phase delay, but this virtual phase cannot reflect a sudden change in the grid voltage at the instant the voltage sag occurs. As a result, the peak value is drastically distorted, and it settles down slowly. A modified APF generates the virtual q-axis voltage component from the difference between the current and the previous values of the d-axis voltage component in the stationary reference frame. However, the modified APF cannot detect the voltage sag and peak value when the sag occurs around the zero crossing points such as 0° and 180°, because the difference voltage is not sufficient to detect the voltage sag. The proposed algorithm detects the sag voltage through all regions including the zero crossing voltage. Moreover, the exact voltage drop can be acquired by calculating the q-axis component that is proportional to the d-axis component. To verify the feasibility of the proposed system, the conventional and proposed methods are compared using simulations and experimental results.

• 대한전자공학회논문지
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• 제19권2호
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• pp.38-50
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• 1982

이 논문에서는 변형된 디지탈 Costas loop이라고 불리우는 새로운 형의 digital phase-locked loop(DPLL)을 제안하고 성능을 해석하였다. 제안된 DPLL의 주요 특성은 tan-1(·) 함수를 DPLL에 사용함으로써 phase error detector가 선형 특성을 갖게 되고, 따라서 mod-2π 선형 difference equation에 의해서 그 특성을 설명할 수 있다. 본 논문은 2부로 나뉘어져 1부에서는 먼저 제안된 시스템을 설명하고 잡음이 없는 경우 Phase plane방법에 의해서 1차와 2차 loop의 성능을 해석했다. 초기 조건에 관계없이 locking이 될 수 있는 locking 범위의 식을 유도하고, 경우에 따라서 일어날 수 있는 false lock 또는 oscillation 현상을 설명했다. 이론적인 모든 해석은 컴퓨터 시뮬레이션에 의해서 입증되었다. 논문의 2부에서는 잡음이 있을 경우에 제안된 DPLL의 성능을 해석하였다. Chapman-Kolmogorov 방정식을 사용하여 제안된 시스템의 phase error의 steady state probability density함수, mean 및 variance를 얻었다. 이 결과들은 제 2부에 게재 될 것이다.

• 대한정형도수물리치료학회지
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• 제22권1호
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• pp.9-15
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• 2016

Background: This study was conducted to investigate the effects of unstable modified wall squat exercises accompanied by abdominal drawing-in on the gait variables of healthy adults. Methods: The total number of subjects was 30, and 15 were randomly placed in the training group (TG) and 15 in the control group (CG). To determine the gait variables of TG and CG, step length difference (SLD) stance phase difference (STPD), swing phase difference (SWPD), single support difference (SSD), and step time difference (STD) were measured using OptoGait, a gait analysis system. Results: When the pre-intervention and post-intervention results of TG and CG were compared, statistically significant differences in SLD, STPD, SWPD, SSD and STD of TG were seen. Conclusion: Unstable modified wall squat exercises accompanied by abdominal drawing-in might help reduce the deviation between left and right gait variables during walking.