• Structural Engineering and Mechanics
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• 제75권4호
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• pp.507-518
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• 2020

With the rapid development of rail transit, rail transit noise needs to be paid more and more attention. In order to accurately and effectively analyze the characteristics of low-frequency noise, a prediction model of vibration of box girder was established based on the hybrid FE-SEA method. When the train speed is 140 km/h, 200 km/h and 250 km/h, the vibration and noise of the box girder induced by the vertical wheel-rail interaction in the frequency range of 20-500 Hz are analyzed. Detailed analysis of the energy level, sound pressure contribution, modal analysis and vibration loss power of each slab at the operating speed of 140 km /h. The results show that: (1) When the train runs at a speed of 140km/h, the roof contributes more to the sound pressure at the far sound field point. Analyzing the frequency range from 20 to 500 Hz: The top plate plays a very important role in controlling sound pressure, contributing up to 70% of the sound pressure at peak frequencies. (2) When the train is traveling at various speeds, the maximum amplitude of structural vibration and noise generated by the viaduct occurs at 50 Hz. The vibration acceleration of the box beam at the far field point and near field point is mainly concentrated in the frequency range of 31.5-100 Hz, which is consistent with the dominant frequency band of wheel-rail force. Therefore, the main frequency of reducing the vibration and noise of the box beam is 31.5-100 Hz. (3) The vibration energy level and sound pressure level of the box bridge at different speeds are basically the same. The laws of vibration energy and sound pressure follow the rules below: web

• 대한토목학회논문집
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• 제34권5호
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• pp.1435-1442
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• 2014

본 연구에서는 OpenFOAM에서 제공하는 소스코드를 이용하여 매끄러운 하상의 직사각형 개수로 흐름에 대해 수치모의를 수행하였다. 난류 해석을 위해 LES를 수행하였는데, 비등방성 잔여 응력항을 모델링하기 위해서 Germano et al. (1991)이 제시한 Dynamic Subgrid-scale 모형을 이용하였다. 조직구조를 분석하기 위하여 Lu and Willmarth (1973)가 제시한 uw 사분면기법을 이용하여 순간레이놀즈 응력이 레이놀즈 응력에 미치는 영향을 기여율과 시간비로 나누어 분석하였다. LES 모의 결과를 토대로 기존 실험 및 DNS 모의 결과와 비교하고 분석하였다. 매끈한 하상을 가진 개수로 흐름에서 완충층 이후의 구간에서 분출현상이 쓸기현상에 비해 레이놀즈 응력의 양의 생성에 기여하는 바가 크지만, 분출현상에 비해 쓸기현상의 발생빈도가 큰 것으로 확인되었다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제7권5호
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• pp.873-887
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• 2015

The springing response of a large blunt ship was considered to be influenced by a second order interaction between the incoming irregular wave and the blunt geometry of the forebody of the ship. Little efforts have been made to simulate this complicated fluid-structure interaction phenomenon under irregular waves considering the second order effect; hence, the above mentioned premise still remains unproven. In this paper, efforts were made to quantify the second order effect between the wave and vibrating flexible ship structure by analyzing the experimental data obtained through the model basin test of the scaled-segmented model of a large blunt ship. To achieve this goal, the measured vertical bending moment and the wave elevation time history were analyzed using a higher order spectral analysis technique, where the quadratic interaction between the excitation and response was captured by the cross bispectrum of two randomly oscillating variables. The nonlinear response of the vibrating hull was expressed in terms of a quadratic Volterra series assuming that the wave excitation is Gaussian. The Volterra series was then orthogonalized using Barrett's procedure to remove the interference between the kernels of different orders. Both the linear and quadratic transfer functions of the given system were then derived based on a Fourier transform of the orthogonalized Volterra series. Finally, the response was decomposed into a linear and quadratic part to determine the contribution of the second order effect using the obtained linear and quadratic transfer functions of the system, combined with the given wave spectrum used in the experiment. The contribution of the second order effect on the springing response of the analyzed ship was almost comparable to the linear one in terms of its peak power near the resonance frequency.

• Structural Monitoring and Maintenance
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• 제7권1호
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• pp.13-25
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• 2020

One of the most important aspects in structural health monitoring is the detection of fatigue damage. Structural components such as heavy-duty bolts work under high dynamic loads, and thus are prone to accumulate fatigue damage and cracks may originate. Those heavy-duty bolts are used, for example, in wind power generation and mining equipment. Therefore, the investigation of new and more effective monitoring technologies attracts a great interest. In this study the acoustic emission (AE) technology was employed to detect incipient damage during fatigue testing of a M36 bolt. Initial results showed that the AE signals have a high level of background noise due to how the load is applied by the fatigue testing machine. Thus, an advanced signal processing method in the time-frequency domain, the Hilbert-Huang Spectrum (HHS), was applied to reveal AE components buried in background noise in form of high-frequency peaks that can be associated with damage progression. Accordingly, the main contribution of the present study is providing insights regarding the detection of incipient damage during fatigue testing using AE signals and providing recommendations for further research.

• The Journal of Asian Finance, Economics and Business
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• 제4권4호
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• pp.67-77
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• 2017

The purpose of this research is to explore the factors affecting on Supply chain (SC). In fact, the collaborative supply chain (CSC) concept in Vietnam is quite new. Apart from obvious differences of doing business between Western versus and most of developing countries such as Vietnam, the literature suggests that collaboration in the supply chain (SC) of the furniture industry are quite low. The primary reason for such low adoption rates is low awareness of enterprises. In order to achieve the purpose of this study, a literature survey related to SC, CSC was carried out, and an empirical analysis was conducted among 276 manufacturers in this industry with the results analyzed. Using Cronbach's alpha analysis, Explore Factor Analysis (EFA) and Regression Analysis (RA) with primary data collected 276 valid samples from 393 samples in Vietnam, this paper explores and confirms that there are existed six basic factors affecting the collaboration in supply chain including: (i) Trust; (ii) Power; (iii) Maturity; (iv) Strategy; (v) Culture; and (vi) Frequency. Results of the research show strong evidences for policy makers and enterprises for management the supply chain collaboration in furniture industry as well as its contribution to literature review of supply chain management.

• 유통과학연구
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• 제20권2호
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• pp.101-108
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• 2022

Purpose: In this logistics disturbance period, this study conducts research of distribution and logistics firms in Korea. The purpose of this exploratory research is to analyze global competitive capability influence on business performance. And give managerial implications and contribute to academics. Research design, data, and methodology: This research empirically analyzes the relationship between global competitive capability and business performance. As for business performance this research considered non-financial performance and measured with business performance fulfillment. As for antecedent variables, this research measured three global competitive capability constructs; preparation, utilization, intensive capability. And each construct includes two capability concepts. This study used 2,316 executing direct export distribution and logistics industry firmsfrom KOTRA's GCL data. This research used frequency analysis, reliability analysis, correlation analysis, and step-wise regression analysis by SPSS26. Results: The result shows that all the variables except export infra showed statistically significant. As results show, mid/long strategy & global mind of preparation capability, both communication and marketing of utilization capability and market strategy and product/goods/service of intensive capability give a positive influence on business performance fulfillment. Conclusions: Based on the results, this research provide implication for practical management, contribution to academic, and suggestion for feature research.

• 동아시아경상학회지
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• 제12권1호
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• pp.1-11
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• 2024

Purpose: This study empirically examines the relations among corporate performance, technology, and corporate capabilities for service companies to find factors that could affect the competitiveness of the service industry. Most study on technology in the service industry have been conducted in developed countries, and yet there exist not sufficient empirical reviews. Research design, data and methodology: This paper, using rare empirical data, examines Korea's service industry and aims to make an academic and managerial contribution to the understanding of the relation between corporate competence and performance. This study analyzes 567 Korean Domestic Companies in Non-manufacturing and Service Industry, using the 2020 Detailed Survey of Venture Businesses (2500) data. Frequency analysis, correlation analysis, and regression analysis are performed. Results: Results show, Hypothesis 1 that internal competence has positive influence on technological strength, is supported. However, Hypothesis 2 that technological strength mediates between internal competence and business performance, Hypothesis 3 that external competence has positive influence on technological strength and Hypothesis 4 that technological strength mediates between external competence and business performance are all partially supported/rejected. Conclusions: This study suggests that technological strength is an important factor that affects both market share and sales. And mediating effect of technology strength emphasized in market share. However, in managing sales, more cautious approach and a more detailed analysis are needed..

• 유통과학연구
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• 제12권7호
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• pp.23-35
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• 2014

Purpose - This study aims to explore the effects of social responsibility activities and business ethics practices on corporate trust and loyalty in the context of a large retail distribution business. Research design, data, and methodology - The data collected was analyzed using PASW Statistics 18.0. In order to verify the demographic characteristics, frequency analysis was conducted on the data. Results - The results of the study were as follows. First, social responsibility activities had a significant effect on corporate trust. Second, both corporate social responsibility activities and business ethics practices had significant effects on loyalty. Third, corporate trust had a significant effect on loyalty. Fourth, corporate social responsibility activities and consumer protection activities had a partial mediation effect, while environmental protection activities and social contribution activities had complete mediation effects. Conclusions - This study clarified and explained the factors of corporate social responsibility activities and business ethics practices that customers value, and analyzed the influence of these factors on corporate trust and loyalty.

• 한국지역사회생활과학회지
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• 제11권2호
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• pp.1-14
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• 2000

The purpose of this study was to empirically verify influence of objective variables and subjective variables of time management strategy of unmarried men and women and provide a basis for the development of time management. The subject of this study were 370 unmarried men and women and interviewed with a questionnaire. The data were analyzed by SPSS/PC+ program for the frequency, mean, standard deviation, and regression analysis. The major results of this study were as follows: 1. The score of implementing time management strategy of unmarried men and women was the highest. The score of getting support time management strategy of unmarried men and women was the lowest. 2. Variables that affect overall time management strategy were age, academic career, sex, degree of information using fate control orientation and communication. 3. The relative contribution of subjective variables on time management strategy were higher than objective variables.

• 가정과삶의질연구
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• 제8권1호
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• pp.15-30
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• 1990

The purpose of this study was to provide basic data for consumer complaining behavior. For this purpose, questionaire was given to 600 individuals who have resided in Seoul as the housewife consumer and possessed the experience to use the purchased refrigerators within the period of 5 years. 437 data were analyzed by the statistical methods like frequency, percentage, ANOVA, Duncan's Multiple Range Test, X2-test, Pearson's correlation and multiple regression analysis. The results of this study were described as follows; 1) Complaining behavior have shown significant differences according to housewife's age, degree of perceived housewife's consumer education, husband's job and housewife's job. 2) The type of attribution of dissatisfaction have shown significant differences according to husband's job, housewife's job and family income. 3) There was significant difference in the complaining behavior according to the type of causal attribution and responsibility attribution. 4) The complaining behavior was influenced by causal attribution of dissatisfaction, responsibility attribution of dissatisfaction, family income, degree of perceived housewife's consumer education, husband's job and housewife's age. And the relative contribution of each variable explaining the complaining behavior was decreased according to the order of variables that were described.