• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.905-912
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• 2009

1-g shaking table test is conducted to evaluate the dynamic behavior of a soil-structure system under seismic loading condition. A consistent similitude law between the model and prototype is needed to predict the behavior of the prototype structure, quantitatively. The natural frequency of geomaterial decreases with the increase of shaking intensity because of the non-linear property of the geomaterial. This phenomenon affects the applicability of similitude laws in 1-g shaking table tests. In this study, a simple method is suggested to determine the frequency of the input motions in 1-g tests in order to enhance the applicability of similitude laws. Modified input frequency is calculated using the frequency ratio with consideration of the variation of the natural frequency according to the intensity of input ground acceleration. To verify the applicability of the suggested method, a series of 1-g shaking table tests were performed for three different sizes of model piles having an overburden mass on their heads by varying the acceleration and the frequency of input motion. The acceleration amplification ratio on the overburden mass, the lateral displacement at the pile head and the maximum bending moment along the pile depth were measured. The projected behaviors of the virtual prototype based on the measured values of the model tests, where the input frequencies were calculated by the new method, showed good consistency, verifying the applicability of the suggested method.

• 한국벤처창업학회:학술대회논문집
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• 2010.08a
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• pp.5-18
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• 2010

In this article, we try to study the relationship among quality management activities, employee trusts, and employee satisfactions in small venture companies in Korea. Based on the previous studies, we build a couple of hypotheses about communication, process management, business policies, innovative changes, employee trust and employee satisfaction. From our empirical study, we find that communication and innovative changes have an positive effect on employee trust. Also, employee satisfaction is positively influenced by employee trust. Our study provides the following implications for organization management. First, for employee satisfaction, in an organization, it is very important to build employee trusts among higher managements, firms, business processes, evaluations, and employees. Second, in order to build employee trusts, our study shows that improving communications among employees and customers and having continuous innovative changes such as improving current business processes, problem solving, establishing standards and maintaing high productions are important.

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.5
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• pp.101-112
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• 2013

Large eddy simulation was performed to investigate the effect of linearly increasing wall disturbance on the modification of turbulent characteristics of temperature field in the vicinity of the wall. It was noted that temperature variance increased monotonically whereas temperature dissipation decreased significantly, resulting in a noticeable reduction in both time and length-scales. A sudden drop in turbulent Prandtl number down to around 0.25 in the near-wall region indicated that the similarity between velocity and temperature fields decreases near the wall as a result of linear wall disturbance.

• Journal of Korean Society of Archives and Records Management
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• v.13 no.2
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• pp.57-85
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• 2013

This study was aimed at investigating the job characteristics and job environment of records managers who are in archives of autonomous districts, find out the problems with the management of duties for local records managers, and deduce the improvement methods that could help records managers more efficiently perform their duties. Through literature review, the study investigated the concept of basic autonomous districts, the allocated summary and duties of records managers through with basic autonomous districts, and the present conditions and duties of the archives through autonomous Gu offices that were in study. Based on the theories of job characteristics and job environment factors, the study drew up a survey that encompasses the present demographic summary, job characteristics, job environment, and working conditions.

• Journal of the Korea Concrete Institute
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• v.13 no.2
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• pp.146-152
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• 2001

The fractal geometry is a non-Euclidean geometry which discribes the naturally irregular or fragmented shaps, so that it can be applied to fracture behavior of materials to investigate the fracture process. Fractal curves have a characteristic that represents a self-similarity as an invariant based on the fractal dimension. This fractal geometry was applied to the crack growth of cementitious composites in order to correlate the fracture behavior to microstructures of cemposite composites. The purpose of this study was to find relationships between fractal dimensions and fracture energy. Fracture test was carried out in order to investigate the fracture behavior of plain and fiber reinforced cement composites. The load-CMOD curve and fracture energy of the beams were observed under the three point loading system. The crack profiles were obtained by the image processing system. Box counting method was used to determine the fractal dimension, D$_{f}$. It was known that the linear correlation exists between fractal dimension and fracture energy of the cement composites. The implications of the fractal nature for the crack growth behavior on the fracture energy, G$_{f}$ is appearent.ent.

• Journal of the Korean Institute of Gas
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• v.12 no.2
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• pp.77-84
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• 2008

Experimental study was conducted to clarify the importance of buoyancy effects in laminar lifted flames which have been well understood by cold jet similarity theory. To evaluate buoyancy effects, lifted flame behaviors were systematically observed in methane and propane lifted flames diluted with He as changing the fuel nozzle diameter from 0.1 to 6 mm. Important physical parameters such as fuel strength, flame stretch and flame curvature, which were derived through simple physical scaling laws, were estimated. It is experimentally proven that buoyancy effects are important in relatively large fuel nozzle diameter and large fuel dilution with He. The results of Chen et al., which displayed the existence of stably lifted flames for 0.5

• Korean Journal of Labor Studies
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• v.24 no.3
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• pp.73-107
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• 2018

The purpose of this study is to shed light on the characteristics of the social relations of migrant workers in the Ansan area and the factors for the construction of those characteristics. The social relations of migrant workers in the Ansan area are affected by the Korean government's policy of EPS, a short-term rotation policy and its ban on the settlement of migrant workers. These workers are likely to form a temporary and bounded social relationship. The bounded social relationship of migrant workers to society is one of the major factors that put them in social poverty. Ethnic communities, support organizations for migrant workers, and local government agencies have assumed the task of helping build the network among migrant workers of various ethnic backgrounds as well as aiding their participation in local social activities. The status of a temporary resident is the prime reason for spatial exclusion and social poverty among migrant workers. To prevent the exacerbation of these phenomena, this study suggests that the government reconsider its short-term work permit policy for less skilled workers.

• Plant Journal
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• v.15 no.1
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• pp.25-30
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• 2019

In this study, by varying flow patterns, which is one of the hydraulic factors of FAC, a strategy to reduce pipe wall thinning by mass transfer has been investigated. A similarity between heat transfer and mass transfer was verified via theoretical analysis, and local convective heat transfer coefficients were analyzed using a commercial numerical analysis program. When ribs were installed inside and outside of the internal surface in the straight section of the pipe, the maximum local heat transfer coefficient was shown to decrease substantially by up to 24.9% compared to the basic flow depending on the position and shape of ribs. If a guide vein was inserted in the pipe elbow, the maximum local heat transfer coefficient decreased by up to 26.7% compared to the basic flow depending on the internal surface area of the pipe by the guide vein.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.29 no.1
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• pp.82-97
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• 2019

Objective: In this study, in order to investigate the relationship between leadership type and job satisfaction, the types of leadership in medical institutions are divided into transformational leadership, servant leadership and authentic leadership. In addition medical staff and non-medical staff are classified according to their job characteristics, and middle managers and operators are classified according to position. Methods: For this purpose, 589 questionnaires were applied to the medical institutions in Seoul and Gyunggi-do, and empirically analyzed with multiple regression. Results: The results of this study are first, among gender, medical or non-medical staff, position and career experience, men, non-medical staffs, and middle managers showed higher leadership, job engagement, and job satisfaction. Second, servant leadership and authentic leadership have significant positive relationships with job engagement. In the case of medical staff, only servant leadership has a positive effect on job engagement, while in the case of non-medical staff, both servant leadership and authentic leadership have significant influence on job engagement. Job satisfaction was found to have a statistically significant effect of servant leadership and authentic leadership in medical staff and non-medical staff. Third, in the case of middle managers, servant leadership showed a statistically significant effect only on job satisfaction, while servant leadership and authentic leadership had statistically significant effects on job engagement and job satisfaction of operators. Conclusions: This study suggests the possibility and applicability of authentic leadership in addition to transformational leadership and servant leadership in hospital organizations. Also, by identifying differences in the effects on organizational effectiveness, it is also suggested the need for research on identifying leadership factors that reflect strictly distinctive job characteristics.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.3
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• pp.147-155
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• 2022

The accumulated ice and snow during the operation of aircraft and railway vehicles can degrade aerodynamic performance or damage the major components of vehicles. Therefore, it is crucial to predict the temporal growth of ice for operational safety. Numerical simulation of ice is widely used owing to the fact that it is economically cheaper and free from similarity problems compared to experimental methods. However, numerical simulation of ice generally divides the analysis into multi-step and assumes the quasi-steady assumption that considers every time step as steady state. Although this method enables efficient analysis, it has a disadvantage in that it cannot track continuous ice evolution. The purpose of this study is to construct a surrogate model that can predict the temporal evolution of ice shape using reduced-order modeling. Reduced-order modeling technique was validated for various ice shape generated under 100 different icing conditions, and the effect of the number of training data and the icing conditions on the prediction error of model was analyzed.