• Computers and Concrete
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• v.2 no.3
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• pp.239-248
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• 2005

The article presents the results of examination of the fractal dimension D of concrete specimen fracture surfaces obtained in fracture toughness tests. The concretes were made from three different types of coarse aggregate: gravel, dolomite and basalt aggregate. Ordinary concretes (C40) and high-performance concretes (HPC) were subjected to testing after 7, 14, 28 and 90 days of curing, respectively. In fracture toughness and compressive tests, different behaviours of concretes were found, depending on the type of aggregate and class of concrete (C40, HPC). A significant increase in the strength parameters tested occurred also after a period of 28 days (up to the $90^{th}$ day of curing) and was particularly large for concretes C40. Fractal examinations performed on fracture replicas showed that the fractal dimension D was diverse, depending on the coarse aggregate type and concrete class being, however, statistically constant after 7 and 14 days for respective concretes during curing. The fractal dimension D was the greater, the worse strength properties were possessed by the concrete. A cross-grain crack propagation occurred in that case, due to weak cohesion forces at the coarse aggregate/mortar interface. A similar effect was observed for C40 and HPC made from the same aggregate. A greater dimension D was exhibited by concretes C40, in which case the fracture was easier to form compared with high-performance concretes, where, as a result of high aggregate/mortar cohesion forces, the crack propagation was of inter-granular type, and the resulted fracture was flatter.

• Korean Journal of Soil Science and Fertilizer
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• v.46 no.5
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• pp.322-326
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• 2013

Many organic fruit growers adopt cover cropping in their orchards to improve soil properties. A field experiment was conducted to determine the effects of cutting frequency of cover crop (CF) and liquid manure application (LM) on green manure production (GMP) and returnable nutrient content (RNC) in pear orchard. The combined effects of CF and LM were tested at two levels, respectively, with liquid manure ($L_1$) and without liquid manure ($L_0$). After that, cover crops were cut once ($C_1$) and three times ($C_3$) in rye, and twice ($C_2$) and four times ($C_4$) in hairy vetch. The result showed that main factors related to green manure production were different depending on the species. In rye, LM was more effective in increasing the dry weight of cover crop and RNC than CF. In contrast, the parameters were more affected by CF rather than LM in hairy vetch. Thus, it is suggested that different management technique is needed depending on the cover crop species in order to maximize the green manure production in pear orchard.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.6
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• pp.277-286
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• 2020

Research on employee commitment to the organization is necessary for human resource management, and the result is applied in practice to improve organizational effectiveness. The aim of the present study is to explore factors affecting organizational commitment at the small and medium-sized enterprises (SMEs) in Vietnam. Besides, the relationship between organizational commitment and job performance is examined as well. The research was conducted on a sample consisting of 67 white-collar workers and 260 blue-collar workers at SMEs. A total of 327 valid complete questionnaires were input into SPSS 20 database for processing to provide evidence. The research model and hypotheses were tested using the technique of the hierarchical multiple regression analysis. The research resultsrevealed that income, reward and welfare, direct manager, working environment, coworker, and promotion opportunity tended to associate positively with organizational commitment. Besides, the finding also showed that, when the employee has a high organizational commitment, it would lead to high job performance. The main findings of this study provided some managerial implications for SMEs, in general, and managers, in particular. It implies that Vietnam's small and medium-sized enterprises should improve these six factors to retain employees as well as enhance their job performance.

• Steel and Composite Structures
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• v.34 no.3
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• pp.333-345
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• 2020

In the past, many efficient profiles have been developed for cold-formed steel (CFS) members by judicious intermediate stiffening of the cross-sections, and they have shown improved structural performance over conventional CFS sections. Most of this research work was based on numerical modelling, thus lacking any experimental evidence of the efficiency of these sections. To fulfill this requirement, experimental studies were conducted in this study, on efficient intermediately stiffened CFS sections in flexure, which will result in easy and simple fabrication. Two series of built-up sections, open sections (OS) and box sections (BS), were fabricated and tested under four-point loading with same cross-sectional area. Test strengths, modes of failure, deformed shapes, load vs. mid-span displacements and geometric imperfections were measured and reported. The design strengths were quantified using North American Standards and Indian Standards for cold-formed steel structures. This study confirmed that efficient profiling of CFS sections can improve both the strength and stiffness performance by up to 90%. Closed sections showed better strength performance whereas open sections showed better stiffness performance.

• Culinary science and hospitality research
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• v.24 no.3
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• pp.60-70
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• 2018

Rapid economic growth brought material affluence and convenience, but it also has caused a negative issue, such as environmental damage. Therefore, this research holds the purpose of grasping structural influencing relationship of environmental awareness of cook, which is taking an important role in food safety among workers in hotel restaurants with eco-friendly attitude and food safety pursuit behavior. To achieve the purpose, collected materials were tested for the fidelity, organic causation and control effect, using Structural Equation Modeling for frequency analysis, confirmatory factor analysis, credibility analysis and hypothesis testing with SPSS (V23.0) and AMOS (V21.0) programs. Environmental awareness of hotel cook has causation with eco-friendly attitude, and the attitude has meaningful causation with food safety pursuit behavior. That is, it proved that cooks are taking care of their job carefully from the pre-cooking stage while most of people ignore the storing stage. The result shows not only hotel's own training session, cook's level of consciousness on the food safety and they are working with high sense of responsibility. The limitation of this research is that it only conducted with cooks of deluxe hotels in Busan, and it could not include various variables about environmental awareness. Therefore, it is expected that the lacking contents to be dealt by a follow-up study.

• International Journal of Naval Architecture and Ocean Engineering
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• v.10 no.3
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• pp.348-359
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• 2018

A series of indoor simulation tests on a large-sized shaking table was performed, which was used to simulate the earthquake ground motion for the pipe-soil interaction system to be tested. The purpose of this study is to examine the dynamic characteristic and seismic response of a length of PVC pipeline lay on a clay seabed under seismic load. The pipeline was fully instrumented to provide strain and acceleration responses in both transverse and in-line. Dynamical modal tests show that corresponding mode shapes vertically and horizontally are basically the same. But the absolute values of the natural frequencies vertically are all higher than those corresponding values in transverse. It turned out that the geometry configuration of riser affects its stiffness. Seismic response of pipeline depends significantly on the waveform, and Peak Ground Acceleration (PGA). As the seismic loading progressed, the strain response was severe around both TDZ and catenary zone. Additionally, strain responses in top and bottom positions were more severe than the result in left or right side of the pipeline in the same section.

• Korea Journal of Hospital Management
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• v.22 no.1
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• pp.21-39
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• 2017

Purpose : This study was intended to investigate the structural relationship among empowerment, self-efficacy, job motivation, autonomy, critical thinking, job-satisfaction, burnout, and self-achievement. In addition, we tested the moderating effect of the career period on the influence of empowerment. Methodology : The structural equation model was used to test the causal relationship between factors, and t-test, ANOVA, descriptive statistics are applied to analyze the research data. Findings : The result of this study shows that the structural model that is the empowerment encourages the self-efficacy, job motivation, autonomy, and critical thinking, also these factors affect the self-achievement through both the job-satisfaction and burnout is acceptable according to the goodness of fitness indices. In addition, we show that the career period moderates the influence of empowerment on the self-efficacy, job-motivation, and autonomy, but not critical thinking. Usually, the shorter the career period is the higher the influence of empowerment is. This moderating effect means that to give proper empowerment to lower position nurses encourage them, and prevent from burnout. Therefore, they feel job-satisfaction and finally self-achievement. Practical Implications : The empowerment helps the nurse to activate self-efficacy, job motivation, autonomy, critical thinking. Hence, these factors decrease burn-out but increase job satisfaction. Finally a sense of self-perfection increase.

• Steel and Composite Structures
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• v.18 no.4
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• pp.925-946
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• 2015

This paper presents a new cost-effective hybrid GFRP-Concrete deck system that the GFRP panel serves as both tensile reinforcement and stay-in-place form. In order to understand the fatigue behavior of such hybrid deck, fatigue test on a full-scale specimen under sagging moment was conducted, and a series of static tests were also carried out after certain repeated loading cycles. The fatigue test results indicated that such hybrid deck has a good fatigue performance even after 3.1 million repeated loading cycles. A three-dimensional finite element model of the hybrid deck was established based on experimental work. The results from finite element analyses are in good agreement with those from the tests. In addition, flexural fatigue analysis considering the reduction in flexural stiffness and modulus under cyclic loading was carried out. The predicted flexural strength agreed well with the analytical strength from finite element simulation, and the calculated fatigue failure cycle was consistent with the result based on related S-N curve and finite element analyses. However, the flexural fatigue analytical results tended to be conservative compared to the tested results in safety side. The presented overall investigation may provide reference for the design and construction of such hybrid deck system.

• Steel and Composite Structures
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• v.18 no.4
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• pp.971-983
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• 2015

To promote greater acceptance and use of composite RCS systems, a two-bay two-story frame specimen with improved composite RCS joint details was tested in the laboratory under reversed cyclic loading. The test revealed superior seismic performance with stable load versus story drift response and excellent deformation capacity for an inter-story drift ratio up to 1/25. It was found that the failure process of the frame meets the strong-column weak-beam criterion. Furthermore, cracking inter-story drift ratio and ultimate inter-story drift ratio both satisfy the limitation prescribed by the design code. Additionally, inter-story drift ratios at yielding and peak load stage provide reference data for Performance-Based Seismic Design (PBSD) approaches for composite RCS frames. An advantage over conventional reinforced concrete and steel moment frame systems is that the displacement ductility coefficient of the RCS frame system is much larger. To conclude, the test results prove that composite RCS frame systems perform satisfactorily under simulated earthquake action, which further validates the reliability of this innovative system. Based on the test result, some suggestions are presented for the design of composite RCS frame systems.

• Korean Journal of Poultry Science
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• v.42 no.1
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• pp.87-100
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• 2015

It is well known that dietary protein affects the growth performance and carcass composition of poultry. Over the last several decades, numerous studies have been carried out to investigate to optimize the level of dietary protein since the protein is an important and expensive constituent in poultry feed. It is generally accepted that dietary protein should represent a balance of amino acids supporting the requirements for growth and maintenance of birds. A protein with balanced essential amino acids that matches a bird's requirement and sufficient non-essential amino acid nitrogen to enable the synthesis of all of the non-essential amino acids, is referred to as an 'ideal protein'. Feeding of excess protein or amino acids may result in an amount of nitrogen emission. Most common method to reduce nitrogen emission is using diet formulation which has lower dietary crude protein level and higher concentration of amino acid supplements. However, there are conflicting reports whether low protein diets supplemented with synthetic amino acids can obtain the growth performance equal to high protein diets. Excessive nitrogen excretion caused by amino acid imbalance also may influence the environment of poultry house due to ammonia production from uric acid. These environmental conditions may increase the incidence of skin problem or respiratory diseases of chickens. Various strategies based on comprehensive understanding should be tested to optimize nitrogen utilization and reduce nitrogen emission while maintaining the performance in poultry production.