• 전력전자학회논문지
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• 제20권2호
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• pp.182-192
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• 2015

This study develops a digital control scheme with power factor correction for a front-end converter in an electric vehicle battery charger. The front-end converter acts as the boost-type switching-mode rectifier. The converter assumes the two roles of the battery charger, which include power factor control and robust charging performance. The proposed control scheme consists of a charging control algorithm and a grid current control algorithm. The scheme aims to obtain unity input power factor and robust performance. Based on the linear average model of the converter, a constant-current constant-voltage charging control algorithm that passes through only one proportional-integral controller and a current feed-forward path is proposed. In the current control algorithm, we utilized a second band pass filter, a single-phase phase-locked loop technique, and a duty-ratio feed-forward term to control the grid current to be in phase with the grid voltage and achieve pure sinusoidal waveform. Simulations and experiments were conducted to verify the effectiveness of the proposed control scheme, both simulations and experiments.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 춘계학술대회논문집
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• pp.51-55
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• 2007

In this paper Statistical Energy Analysis has been considered to predict high frequency air borne interior noise. Dash panel Insulation is major part to reduce engine excitation noise. Transmission loss and absorption coefficient are considered to predict dash insulation performance. Transmission lose is derived from coupling loss factor and absorption coefficient is derived from internal damping loss factor. Material Biot properties were used to calculate each loss factors. Insulation geometry thickness distribution was hard to measure, so FeGate software was used to calculate thickness map from CAD drawing. Each predicted transmission losses between conventional insulation and light weight insulation were compared with SEA. Transmission loss measurement was performed to validate each prediction result, and it showed good correlation between prediction and measurement. Finally interior noise prediction was performed and result showed light weight insulation system can reduce 40% weight to keep similar performance with conventional insulation system, even though light weigh insulation system has lower sound transmission loss and higher absorption coefficient than conventional system.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.713-717
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• 2014

This paper presents a beamforming technique for locating impulsive sound source. The conventional frequency-domain beamformer is advantageous for localizing noise sources for a certain frequency band of concern, but the existence of many frequency components in the wide-band spectrum of impulsive noise makes the beamforming image less clear. In contrast to a frequency-domain beamformer, it has been reported that a time-domain beamformer can be better suited for transient signals. Although both frequency- and time-domain beamformers produce the same result for the beamforming power, which is defined as the RMS value of its output, we can use alternative directional estimators such as the peak value and crest factor to enhance the performance of a time-domain beamformer. In this study, the performance of three different directional estimators, the peak, crest factor and RMS output values, are investigated and compared with the incoherent interfering noise embedded in multiple microphone signals. The proposed formula is verified via experiments in an anechoic chamber using a uniformly spaced linear array. The results show that the peak estimation of beamformer output determines the location with better spatial resolution and a lower side lobe level than crest factor and RMS estimation in noise free condition, but it is possible to accurately estimate the direction of the impulsive sound source using crest factor estimation in noisy environment with stationary interfering noise.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권2호
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• pp.703-722
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• 2016

Passive wireless devices have increasing civilian and military applications, especially in the scenario with wearable devices and Internet of Things. In this paper, we study indoor localization of a target equipped with radio-frequency identification (RFID) device in ultra-wideband (UWB) wireless networks. With known room layout, deterministic multipath components, including the line-of-sight (LOS) signal and the reflected signals via multipath propagation, are employed to locate the target with one transmitter and a single inaccurate receiver. A factor graph corresponding to the joint posterior position distribution of target and receiver is constructed. However, due to the mixed distribution in the factor node of likelihood function, the expressions of messages are intractable by directly applying belief propagation on factor graph. To this end, we approximate the messages by Gaussian distribution via minimizing the Kullback-Leibler divergence (KLD) between them. Accordingly, a parametric message passing algorithm for indoor passive localization is derived, in which only the means and variances of Gaussian distributions have to be updated. Performance of the proposed algorithm and the impact of critical parameters are evaluated by Monte Carlo simulations, which demonstrate the superior performance in localization accuracy and the robustness to the statistics of multipath channels.

• 한국식품조리과학회지
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• 제24권3호
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• pp.367-374
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• 2008

The principal objective of this study was to determine the influence of physical evidence's performance on perception of value at family restaurants in Seoul. Frequency analysis, t-test, ANOVA, reliability analysis, factor analysis, multiregression analysis were employed to analyze the data. The physical evidence was divided into 3 factors. Factor 1, 'matters related to appearances and decoration'; and Factor 3, matters related to atmosphere' differed significantly with monthly pocket money. However, all factors differed significantly by partner. Additionally, all factors positively(+) influenced customer's perception of value. In particular, factor 1, 'matters related to appearances and decoration' was the most positive factor. As a result, physical evidence can be regarded as efficient marketing tactic by which the intangible factors of restaurant-business may be removed. Therefore, food-service companies should endeavor to manage physical evidence ideally as a means of reducing the negative characteristics of service toward customers and inducing customers perceptions of value at family restaurants.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권2호
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• pp.810-831
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• 2019

Recently, continuous dimensional emotion recognition from audiovisual clues has attracted increasing attention in both theory and in practice. The large amount of data involved in the recognition processing decreases the efficiency of most bimodal information fusion algorithms. A novel algorithm, namely the incomplete Cholesky decomposition based kernel cross factor analysis (ICDKCFA), is presented and employed for continuous dimensional audiovisual emotion recognition, in this paper. After the ICDKCFA feature transformation, two basic fusion strategies, namely feature-level fusion and decision-level fusion, are explored to combine the transformed visual and audio features for emotion recognition. Finally, extensive experiments are conducted to evaluate the ICDKCFA approach on the AVEC 2016 Multimodal Affect Recognition Sub-Challenge dataset. The experimental results show that the ICDKCFA method has a higher speed than the original kernel cross factor analysis with the comparable performance. Moreover, the ICDKCFA method achieves a better performance than other common information fusion methods, such as the Canonical correlation analysis, kernel canonical correlation analysis and cross-modal factor analysis based fusion methods.

• The Journal of Asian Finance, Economics and Business
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• 제7권6호
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• pp.449-456
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• 2020

This study examines the relation between the quality of leader-member relationship and operational performance of processing enterprises employees in Vietnam, while job satisfaction and innovation are as a mediator variable. In depth interviews are first conducted with five managers and professional workers in five processing enterprises to determine the latent variables and build the structured questionnaire with observed variables. A quantitative survey with 438 employees and managers from 300 processing enterprises was carried out. The method of exploratory factor analysis (EFA), Cronbach's alpha analysis, and confirmatory factor analysis (CFA) was used to test the reliability, the convergent nature, and the consistency of the concepts. Structural equation modeling (SEM) is used to test the proposed model. The result shows that job satisfaction, innovation and operational performance have positive effects on the quality of leader-member relationship. The relationship between leaders and members had indirect impact on employee's operational performance via their job satisfaction and innovation, which illustrates a mediator role of job satisfaction and innovation for employees' performance. The findings of this study suggest that managers need to focus on developing relationship with employees to improve their satisfaction, innovation and performance.

• 대한지역사회영양학회지
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• 제11권1호
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• pp.116-123
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• 2006

The purposes of this study were to develop a tool for assessing internal branding performance and to identify the difference of internal branding performance between local and international hotels. The internal branding performance measure was developed through literature studies and face-to-face in-depth interviews with managers in various departments of 5 deluxe hotels. The questionnaires were distributed to 460 employees in food and beverage departments of 11 deluxe hotels in Seoul, and a total of 398 questionnaires were used for analysis ($86.5\%$). The statistical analyses were completed using SPSS Win (12.0) for descriptive analysis, reliability analysis and t-test, and AMOS (5.0) for confirmatory factor analysis. The results of this study showed that the measure developed in this study was reliable and valid for assessing internal branding performances of hotels. In addition, the internal branding performances of hotels were high at understanding of brand dimensions and relatively low at work and organizational culture and human resource management dimensions, and local hotels showed lower levels of performance than international hotels at the dimensions of work and organizational culture (t = -3.801, P < 0.001) and human resource management(t = -5.397, p < 0.001). In conclusion, it is considered that a strong internal branding strategy should be established for successful brand management, and the practical measure for internal branding performance would be a key factor.

• 복식문화연구
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• 제16권4호
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• pp.681-695
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• 2008

This study was accomplished to investigate the preference of clothing materials and the clothing demand performance for underwear and everyday dress of atopic patients. As this study was the research study by a use of a questionnaire, the finally total 987 copies of the collected questionnaires were used to analyze the data. SPSS was used for the statistical analysis of data. To analyze the data, frequency analysis, percentage, $X^2$-test, reliability analysis, factor analysis, t-test, ANOVA and Duncan's multiple comparisons were used. The results obtained are as follows. In factor analysis for clothing materials and the demand performance which atopic patients favor, the preference factors for underwear materials were classified as pliability/a sense of weight, a sense of cold and warmth, tactility, and elasticity. Those for everyday wear were classified as pliability/surface roughness, a sense of cold and warmth, a sense of weight, and elasticity. And the demand performance factors for underwears were classified as thermophysiology, care convenience, and skin contact. Those for everyday wear were classified as comfortableness and care convenience. In the difference analysis for the preference and the demand performance, Both everyday wear and underwear showed a significant difference for the preference and the demand performance according to gender, age, income, education level, and occupation.

• 여성건강간호학회지
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• 제13권2호
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• pp.98-104
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• 2007

Purpose: The purpose of this study was to explore the barriers and the enhancing factors and predictors to postpartum care performance. Methods: The Research design in this study was a cross-sectional correlational survey. Subjects were 145 women at 6 to 10 weeks post delivery at an OB & GY clinic. Data was gathered with postpartum care performance, and other related variables including emotional status during pregnancy, fatigue, health recovery status, maternal role and identity. Data was analyzed using the SPSS WIN(version 11.0) program. Results: The mean score of postpartum care performance was 3.08 of 5, it had significant differences in emotional status during pregnancy, coincidence of expected sex, health recovery status, postpartum fatigue and postpartum depression. The maternal role and health recovery status were enhancing factors of postpartum care performance. Also, the barrier factors were fatigue, depression and coincidence of expected sex. Among these factors, the present health recovery status had an predictability of 11.7%, postpartum fatigue 3.2%, and coincidence of expected sex 2.5%, for a total predictability factor of 17.4% on postpartum care performance. Conclusion: Among these related factors to postpartum care performance, present health recovery status was the most predictable factor and then postpartum fatigue, and coincidence of expected sex. We need to establish a strategy to reduce postpartum fatigue and implement nursing interventions for health related consequences in postpartum women.