• International Journal of Fluid Machinery and Systems
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• v.9 no.1
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• pp.39-46
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• 2016

A high frequency hydraulic rock drill drifter with sleeve valve is developed to use on arm of excavator. In order to ensure optimal working parameters of impact system for the new hydraulic rock drill drifter controlled by sleeve valve, the performance test system is built using the arm and the hydraulic source of excavator. The evaluation indexes are gained through measurement of working pressure, supply oil flow and stress wave. The relations of working parameters to impact system performance are analyzed. The result demonstrates that the maximum impact energy of the drill drifter is 98.34J with impact frequency of 71HZ. Optimal pressure of YZ45 rock drill is 12.8 MPa-13.6MPa, in which the energy efficiency reaches above 58.6%, and feature moment of energy distribution is more than 0.650.

• Steel and Composite Structures
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• v.52 no.6
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• pp.609-620
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• 2024

The impact problem of imperfect beams is crucial in engineering fields such as water conservancy and transportation. In this paper, the low velocity impact of graphene reinforced metal foam beams with geometric defects is studied for the first time. Firstly, an improved Hertz contact theory is adopted to construct an accurate model of the contact force during the impact process, while establishing the initial conditions of the system. Subsequently, the classical theory was used to model the defective beam, and the motion equation was derived using Hamilton's principle. Then, the Galerkin method is applied to discretize the equation, and the Runge Kutta method is used for numerical analysis to obtain the dynamic response curve. Finally, convergence validation and comparison with existing literature are conducted. In addition, a detailed analysis was conducted on the sensitivity of various parameters, including graphene sheet (GPL) distribution pattern and mass fraction, porosity distribution type and coefficient, geometric dimensions of the beam, damping, prestress, and initial geometric defects of the beam. The results revealed a strong inhibitory effect of initial geometric defects on the impact response of beams.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.1075-1075
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• 2006

• Journal of Communications and Networks
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• v.18 no.5
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• pp.688-698
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• 2016

In this paper, we investigate the achievable sum rate and energy efficiency of downlink massive multiple-input multiple-output antenna systems with zero-forcing precoding, by taking into account the randomness of user locations. Specifically, we propose two types of non-uniform user distributions, namely, center-intensive user distribution and edge-intensive user distribution. Based on these user distributions, we derive novel tight lower and upper bounds on the average sum rate. In addition, the impact of user distributions on the optimal number of users maximizing the sum rate is characterized. Moreover, by adopting a realistic power consumption model which accounts for the transmit power, circuit power and signal processing power, the energy efficiency of the system is studied. In particular, closed-form solutions for the key system parameters, such as the number of antennas and the optimal transmit signal-to-noise ratio maximizing the energy efficiency, are obtained. The findings of the paper suggest that user distribution has a significant impact on the system performance: for instance, the highest average sum rate is achieved with the center-intensive user distribution, while the lowest average sum rate is obtained with the edge-intensive user distribution. Also, more users can be served with the center-intensive user distribution.

• Journal of Distribution Science
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• v.18 no.5
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• pp.61-70
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• 2020

Purpose: The aim of this paper is to investigate whether labor unions are the main determinants of advertising expenditures and whether market competition has an impact on the relation between labor unions and advertising expenditures, focusing on distribution firms. Research design, data, and methodology: Using 914 observations of KOSPI market from 2001 to 2009 in distribution firms, this paper examines whether labor union is related to advertising expenditures, focusing on distribution firms. For this, this paper employs not only OLS regressions method but also 2SLS regressions method in which Female_Ratio(percentage of female employees) is used as instrumental. Results: This paper finds that in the distribution firms, labor union, as a major stakeholder of the company is, in terms of statistic, negatively associated with advertising expenditures. Also, market competition, in this paper, doesn't have real impact on the relation between labor unions and advertising expenditures. Conclusions: This paper presents the influence of labor unions, as a major factor in determining advertising expenditures. An executive who understands that as the amount of advertising expenditure increases, the total pie of wages to be attributed to the members of labor union will decrease.

• Journal of Distribution Science
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• v.19 no.9
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• pp.101-111
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• 2021

Purpose: This study discusses and discovers the important role of fashion product coolness in affecting consumers' perceived value and consumers' value creation behavior. Accordingly, fashion product coolness exerts a direct effect on perceived value while perceived value has a direct impact on value creation. Besides, fashion product coolness has an indirect effect on value creation through perceived value. Research design, data, and methodology: This study adopts the quantitative research approach by cross-sectional technical on a sample of 319 respondents in Vietnam. PLS-SEM has been used to analyze the survey data. Results: The result indicates that the proposed direct and indirect effects are significant. Specifically, utilitarian "coolness" and hedonic "coolness" have positive impacts on perceived value. The perceived value poses an impact on consumers' value creation behavior, including customer lifetime value and influencer value. Finally, the perceived value links utilitarian "coolness", hedonic "coolness" with customer lifetime value and influencer value. Conclusions: Fashion distribution is playing an increasingly important role in the retail sector of the economy. Fashion distribution activities are greatly influenced by the perceived value of consumers. The findings are supposed to strengthen the beliefs of fashion brands and retailers in the promotion of value creation and consumers' perceived value in the field of fashion distribution.

• Korean Journal of Applied Biomechanics
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• v.15 no.3
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• pp.1-7
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• 2005

Excessive pronation and impact force during running are related to various running injuries. To prevent these injuries, three type of running shoes are used, such as cushioning, stability, and motion control. Although there were may studies about the effect of midsole hardness on impact force, no study to investigate biomechanical effect of motion control running shoes. The purpose of this study was to determine biomechanical difference between cushioning and motion control shoes during treadmill running. Specifically, plantar and rearfoot motion, impact force and loading rate, and insole pressure distribution were quantified and compared. Twenty male healthy runners experienced at treadmill running participated in this study. When they ran on treadmill at 3.83 m/s. Kinematic data were collected using a Motion Analysis eight video camera system at 240 Hz. Impact force and pressure distribution data under the heel of right foot were collected with a Pedar pressure insole system with 26 sensors at 360 Hz. Mean value of ten consecutive steps was calculated for kinematics and kinetics. A dependent paired t-test was used to compare the running shoes effect (p=0.05). For most kinematics, motion control running shoes reduced the range of rearfoot motion compared to cushioning shoes. Runners wearing motion control shoe showed less eversion angle during standing less inversion angle at heel strike, and slower eversion velocity. For kinetics, cushioning shoes has the effect to reduce impact on foot obviously. Runners wearing cushioning shoes showed less impact force and loading rate, and less peak insole pressure. For both shoes, there was greater load on the medial part of heel compared to lateral part. For pressure distribution, runners with cushioning shoes showed lower, especially on the medial heel.

• Journal of Distribution Science
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• v.16 no.9
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• pp.25-33
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• 2018

Purpose - The purpose of the study is to analyze the empowerment intermediary role on the relationship between the job distribution and the quality of life. A research on empowerment and social service staffs' job distribution also should be conducted to improve the quality of their lives. Because empowerment, particularly, affects the quality of life, it should be taken a detail discussion for empowerment improvement. Research design, data, and methodology - This paper conducted a questionnaire survey. In total, 722 copies of the structural questionnaire were analyzed. Five parameter subsets were selected to measure the empowerment such as task significance, role performance capability, self-determination, task impact, then, the survey consists of 10 questions. For data analysis, confirmatory factor analysis, discriminant and concentration validity analysis, path coefficient significance, and mediation effectiveness verification were employed. Results - As evidenced from the data analysis, job distribution variables such as job impact, job autonomy, and feedback affect the quality of their lives. Empowerment also affects the quality of their lives. Next, the empowerment functions as meditating role in the relationships with job impact, job autonomy, feedback and the quality of their lives. On the other hand, the empowerment do not function as meditating role in the relationships with social service staffs' function diversity and the quality of their lives. Conclusions - It is necessary to conduct ways for various job performance and outside educational facilities to improve social service staffs' function diversity. The mission, vision, strategic purposes, detailed execution goals need to be set by all their organization members' participation. Empowerment also requires social welfare facilities' drastic delegation on their authority and responsibilities with their active decentralization in the organization.

• Journal of Distribution Science
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• v.20 no.2
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• pp.31-41
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• 2022

Purpose: Developing and nurturing supply chain dynamic capability is one of the leading solutions to create competitive advantages, maintain growth and sustainable development for businesses. The study was conducted to experimentally confirm the impact of supply chain dynamic capability on competitiveness and business efficiency for Vietnamese wood enterprises. Research design, data and methodology: The study surveyed 236 managers of Vietnamese wood manufacturing and distribution enterprises. The authors applied the structural equation modeling (SEM) to analyze the relationship between the dynamic capability of the supply chain and the competitiveness, business efficiency of enterprises to achieve those goals. Results: The results show that businesses owning supply chain dynamic capability will have better competitiveness and business efficiency. Especially, in the context of Vietnamese wood sector, the larger the scale of business, the more profound the impact of supply chain dynamic capability on competitiveness and business efficiency. Conclusions: Focusing on developing supply chain dynamics would be a promising solution to improve the competitiveness of Vietnam's wood enterprises in the global market.

• Journal of Distribution Science
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• v.21 no.5
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• pp.1-9
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• 2023

Purpose: Marketing and especially distribution channels has proved challenging for small and medium-sized enterprises (SMEs) worldwide due to its exorbitant cost. The objective of this study is to access the role and impact of digital marketing as a new distribution channel in companies located in Kosovo. Research design, data and methodology: To achieve the objective of the research, data was collected from 64 respondents/participants working in different organizations and sectors. Results: The result of the data collected showed that digital marketing plays a huge role and an effective medium in distribution of products and services, and helps in boosting sales of companies. The results showed that this form of marketing helps with retention of customers and cost effectiveness. Conclusions: The managerial implication of this study is that it is believed that customers in the topical conversation region are impacted by Kosovo businesses and their online marketing initiatives. The results of this study suggest that marketers and managers should take advantage of social media in order to accomplish the study's main objective. However, for enhanced productivity and high-level effectiveness of Digital marketing in Kosovo, there should be proper sensitization on the available digital marketing options and how it can be done.