• 한국보육지원학회지
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• 제19권6호
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• pp.79-95
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• 2023

Objective: This study examines the relationships among four-year-olds' counting skills, their use of number words, and their mothers' use of number words during mother-child free play. Specifically, we assess whether children's use of number words mediates the relationship between their counting skills and their mothers' use of number words during play. Methods: Forty-two 4-year-old children and their mothers were asked to play freely with a given set of toys at their home for 10 minutes. Children also completed a counting skill test. Frequencies of number word use were calculated for mothers and children from transcriptions of the free play. Results: Children's counting skills, the frequency of their number word use, and their mothers' frequency of number word use were positively correlated with each other. Additionally, the frequency of children's number-word use completely mediated the relationship between their counting skills and their mothers' frequency of number-word use. Conclusion/Implications: The results suggest that children's use of number language may play a crucial role in the provision of number-related language input by parents, based on their children's math skills. Practical implications of the findings are discussed.

• International Journal of Precision Engineering and Manufacturing
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• 제2권4호
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• pp.81-88
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• 2001

We present a new digital phase measuring method for heterodyne optical interferometry, which providers high measuring speed up to 6 m/s with a fine displacement resolution of 0.1 nanometer. The key idea is combining two distinctive digital phase measuring techniques with mutually complementary characteristics to earth other one is counting the Doppler shift frequency counting with 20 MHz beat frequency for high-velocity measurement and the other is the synchronous phase demodulation with 2.0 kHz beat frequency for extremely fine displacement resolution. The two techniques are operated in switching mode in accordance wish the object speed in a synchronized way. Experimental results prove that the proposed dual mode phase measuring scheme is realized with a set of relatively simple electronic circuits of beat frequency shifting, heterodyne phase detection. and low-pass filtering.

• Journal of Power Electronics
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• 제18권3호
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• pp.910-922
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• 2018

Conventional battery state-of-charge (SoC) estimation methods either involve sophisticated models or consume considerable computational resource. This study constructs an enhanced coulomb counting method (Ah method) for the SoC estimation of lithium-ion batteries (LiBs) by expanding the Peukert equation for the discharging process and incorporating the Coulombic efficiency for the charging process. Both the rate- and temperature-dependence of battery capacity are encompassed. An SoC mapping approach is also devised for initial SoC determination and Ah method correction. The charge counting performance at different sampling frequencies is analyzed experimentally and theoretically. To achieve a favorable compromise between sampling frequency and accumulation accuracy, a frequency-adjustable current sampling solution is developed. Experiments under the augmented urban dynamometer driving schedule cycles at different temperatures are conducted on two LiBs of different chemistries. Results verify the effectiveness and generalization ability of the proposed SoC estimation method.

• 정보관리학회지
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• 제29권1호
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• pp.115-134
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• 2012

전통적인 저자동시인용분석은 인용색인 데이터베이스가 색인하는 제 1저자만을 대상으로 하기 때문에 제1저자 이외의 저자의 기여도가 제외된다는 한계를 지니고 있다. 본 연구의 목적은 경제학 분야를 대상으로하여 복수저자기반의 저자동시인용분석을 활용하여 해당 학문분야의 지적구조를 제시하고자 한다. 이를 위하여 네 가지 실험집단을 구성하였다. (1) 인용된 문헌의 제 1저자만을 고려한 저자동시인용분석, (2) 문헌당 총합 제한 없이 복수저자에게 동일한 인용빈도 부여한 저자동시인용분석, (3) 문헌당 총 합을 제한하여 인용빈도를 부여한 저자동시인용분석, (4) 저자기입 순서를 고려하여 인용빈도를 부여한 저자동시인용분석. 본 연구의 결과는 크게 제 1저자만 고려한 방식과 복수저자를 모두 고려한 방식에 따라 군집형성에 있어서 차이를 보였다. 또한 복수저자의 인용빈도를 구하는 방식에 따라서 군집의 소속이 달라지는 변화를 찾아볼 수 있다. 이러한 결과는 공동저작이 증가하는 학문적 추세에 비추어서 학문의 지적구조를 밝히기 위해서는 복수저자가 고려된 저자동시인용분석이 중요하다는 점을 시사한다.

• 제어로봇시스템학회논문지
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• 제21권6호
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• pp.547-552
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• 2015

In this paper, an ARS-EKF based motion counting algorithm for repetitive exercises such as calisthenics is proposed using a smartwatch. Raw sensor signals from accelerometers and gyroscopes are widely used for conventional smartwatch counting algorithms based on pattern recognition. However, generated features from raw data are not intuitive to reflect the movement of motions. The proposed motion counter algorithm is composed of navigation based feature generation and counting with error correction. The candidate features for each activity are velocity and attitude calculated through an ARS-EKF algorithm. In order to select those features which reveal the characteristics of each motion, an exercise frame from the initial sensor frame is introduced. Counting processes are basically based on the zero crossing method, and misdetected counts are eliminated via simple classification algorithms considering the frequency of the counted motions. Experimental results show that the proposed algorithm efficiently and accurately counts the number of exercises.

• 한국소음진동공학회논문집
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• 제15권2호
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• pp.239-247
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• 2005

This paper deals with the development of a contact-type counting device using a piezoelectric polymer film as a sensor. The piezoelectric and vibration characteristics of the film under a bending vibration were investigated theoretically and experimentally. A counting device, which includes filters, an amplifier, an analog-digital converter, and a display, was designed and fabricated. The performance of the piezoelectric polymer sensor was evaluated in the sense of the responses to contact force, contact frequency, and contact speed. The life and the temperature effect were also investigated for the piezoelectric film sensor.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2007년도 정기 학술대회 논문집
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• pp.387-392
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• 2007

The loss of strength in an aircraft structure as a result of cyclic stress over a period of life time is an important phenomenon for aircraft analysis. Load/stress spectrum can be constructed from the occurrence frequency based on the load/stress histories during a service lifetime. In this paper, three types of fatigue spectrum was compared. The rainflow counting method was applied to concentrate the stress spectrum obtained from the flight loads recorder(FLDR). A fatigue analysis for different stress spectrum was performed by using LUSAS computer application.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.1089-1092
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• 2004

This paper deals with the development of a contact-type counting device using a piezoelectric polymer film as a sensor. The piezoelectric and vibration characteristics of the film under a bending vibration were investigated theoretically and experimentally. A counting device, which includes filters, an amplifier, an analog-digital converter, and a display, was designed and fabricated. The performance of the piezoelectric polymer sensor was evaluated in the sense of the responses to contact force, contact frequency, and contact speed. The life and the temperature effect were also investigated for the piezoelectric film sensor.

• 한국소음진동공학회논문집
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• 제22권12호
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• pp.1227-1236
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• 2012

The low speed machinery faults are usually caused by the bearing failure of the rolling elements. As the life time of the bearing is limited, the condition monitoring of bearing is very important to maintain the continuous operation without failures. A few monitoring techniques using time domain, frequency domain and fuzzy neural network vibration analysis are introduced to detect and diagnose the faults of the low speed machinery. This paper presents a method of fault detection for the rolling element bearing in the low speed machinery using the Wiener filtering and shock pulse counting techniques. Wiener filter is used for noise cancellation and it clearly makes the shock pulse emerge from the time signal with the high level of noise. The shock pulse counting is used to determine the various faults obviously from the shock signal with transient pulses not related with the bearing fault. Machine fault simulator is used for the experimental measurement in order to verify this technique is the powerful tool for the low speed machine compared with the frequency analysis. The test results show that the method proposed is very effective parameter even for the signal with high contaminated noise, speed variation and very low energy. The presented method shows the optimal tool for the condition monitoring purpose to detect the various bearing fault with high accuracy.

• Structural Engineering and Mechanics
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• 제28권4호
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• pp.387-410
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• 2008

The fatigue damage accumulation rates of horizontally curved thin walled box-girder bridge have been estimated from vehicle-induced dynamic stress history using rain flow cycle counting method in the time domain approach. The curved box-girder bridge has been numerically modeled using computationally efficient thin walled box-beam finite elements, which take into account the important structural actions like torsional warping, distortion and distortional warping in addition to the conventional displacement and rotational degrees of freedom. Vehicle model includes heave-pitch-roll degrees of freedom with longitudinal and transverse input to the wheels. The bridge deck unevenness, which is taken as inputs to the vehicle wheels, has been assumed to be a realization of homogeneous random process specified by a power spectral density (PSD) function. The linear damage accumulation theory has been applied to calculate fatigue life. The fatigue life estimated by cycle counting method in time domain has been compared with those found by estimating the PSD of response in frequency domain. The frequency domain method uses an analytical expression involving spectral moment characteristics of stress process. The effects of some of the important parameters on fatigue life of the curved box bridge have been studied.