• Computers and Concrete
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• v.12 no.5
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• pp.669-680
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• 2013

This paper unveils a new computer based stabilization methodology for automated modeling analysis and its experimental verification for corrosion in reinforced concrete structures under the effect of varying oxygen concentration. Various corrosion cells with different concrete compositions under four different environmental conditions (air dry, submerged, 95% R.H and alternate wetting-drying) have been investigated under controlled laboratory conditions. The results of these laboratory tests were utilized with an automated computer-aided simulation model. This model based on mass and energy stabilization through the porous media for the corrosion process was coupled with modified stabilization methodology. By this coupling, it was possible to predict, maintain and transfer the influence of oxygen concentration on the corrosion rate of the reinforcement in concrete under various defined conditions satisfactorily. The variation in oxygen concentration available for corrosion reaction has been taken into account simulating the actual field conditions such as by varying concrete cover depth, relative humidity, water-cement ratio etc. The modeling task has been incorporated by the use of a computer based durability model as a finite element computational approach for stabilizing the effect of oxygen on corrosion of reinforced concrete structures.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.2164-2168
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• 2003

Real time control system such as in factory automation fields, defense field, aerospace, railway industries, financial trading and so forth, includes multiple computers on multiple nodes, and share data to process various actions and functions. This is similar to multitasking in a multiprocessor computer system. The task processing efficiency of such system is proportionally increased by process speed of each process computer. And also it is greatly influenced by communication latencies of each node. To provide proper operation of such real time system, a network that can guarantee deterministic exchange of certain amount of data within a limited time is required. Such network is called as a real time network. As for modern distributed control system, the timeliness of data exchange gives important factor for the dynamics of entire control system. In a real time network system, exchanged data are determined by off-line design process to provide the timeliness of data. In other word, designer of network makes up a network data table that describes the specification of data exchanged between control equipments. And by this off-line design result, the network data are exchanged by predetermined schedule. First, this paper explains international standard real time network TCN (Train Communication Network) applied to the KHST (Korean High Speed Train) project. And then it explains the computer program developed for design tool of network data table of TCN.

• School Mathematics
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• v.19 no.2
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• pp.405-421
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• 2017

This study provides a concrete example of the development of the task in collaboration with the in-service teacher and the pre-service teacher. In the process, the roles of pre-service teachers and in-service teachers were analyzed and the possibility of cooperation was grasped. As a result, pre-service teachers and field teachers considered the level and interest of the students and considered mathematical contents in the process of developing the tasks. Each subject did not directly consider the interaction of the students and contents, but they could confirm the improvement of the tasks as their roles affected each other.

• Smart Structures and Systems
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• v.19 no.2
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• pp.213-224
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• 2017

The electromagnetic field can cause an essential change of the dynamic behavior of the railgun. The evaluation of the dynamics performance of railgun is a mandatory task. Here, a nonlinear electromagnetic force equation of the railgun is given in which the clearance, the thickness and the width of the rail are considered. Based on it, the nonlinear electromechanical coupled dynamics equations of Euler beam rails for the railgun are proposed. Using the equations, the nonlinear free vibration frequency of the railgun is investigated and the effects of the system parameters on the frequency are analyzed. The nonlinear forced responses of the rail to the electromagnetic excitation are investigated as well. The results show that as the nonlinearity of the railgun system is considered, the vibration frequencies of the railgun system increase; as the current in the rail increases, the difference between the natural frequencies and the nonlinear vibration frequencies increases significantly; the nonlinearity of the railgun system is more obvious for smaller distance between the two rails, smaller rail thickness, and smaller stiffness of the elastic foundation; the unstable dynamics state of the rail system occurs when the armature runs to the exit of the railgun. The results are useful for design and application of the railgun system.

• The Journal of Korea Robotics Society
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• v.13 no.3
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• pp.151-156
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• 2018

Military robots are expected to play an important role in the future battlefield, and will be actively engaged in dangerous, repetitive and difficult tasks. During the robots perform the tasks a human operator controls the robots in a supervisory way. The operator recognizes battlefield situations from remote robots through an interface of the operator control center, and controls them. In the meantime, operator workload, controller interface, robot automation level, and task complexity affect robot operability. In order to assess the robot operability, we have developed ROSim (Robot Operational Simulator) incorporating these operational factors. In this paper, we introduce the results of applying ROSim experimentally to the assessment of reconnaissance robot operability in a battle field. This experimental assessment shows three resulting measurements: operational control workload, operational control capability, mission success rate, and discuss its applicability to the defense robot research and development. It is expected that ROSim can contribute to the design of an operator control center and the design analysis of a human-robot team in the defense robot research and development.

• Journal of Technologic Dentistry
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• v.41 no.4
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• pp.347-358
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• 2019

Purpose: The purpose of this study was to analyze dental technicians' job stress and Job satisfaction level and to examine its correlation. Methods: A self-administered survey was conducted from September 2 to October 2, 2019, on 230 selected dental technicians. The collected data were statistical data on frequency and percentage were obtained, and t-test, one-way ANOVA, correlation analysis and regression analysis were carried out. Results: When the job stress was analyzed, there were significant differences according to their field of work, working hours(p<.05). Their average score in the items about a job stress was 3.57. As a result of analyzing the job satisfaction of the dental technicians, there were significant differences according to their working hours, plan for task continuity in dental technician(p<.05). The average score in job satisfaction items was 3.11. Conclusion: As a result of research, that as for the correlation between a job stress and job satisfaction, a higher the job stress led to lower the job satisfaction, as every variable had a significant reverse correlation with each other. In addition, physical environment, heavy workload, conflict during the work performance, personal matters were identified as the factor that exerted the influence on both of job satisfaction.

• Archives of design research
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• v.16 no.3
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• pp.123-132
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• 2003

This research has started from a critical mind that raised a question how we will view the minimal tendencies of graphic design in historical context that is newly raised again after the late 1990s. In chapter 1, I examined the main ideas of the twentieth century such as "Less is more", "Less is boring", and "I believe in less and more". In chapter 2, I studied the minimal tendencies and the distinctions in graphic design by chronological order. 1 became to think that the recent minimal tendencies of graphic design appears naturally in the process of newly redefining ones specialty and identity from accepting the rapidly changing of social/cultural/technical changes rather than being temporary trend, Furthermore, I realized that considering the distinctiveness of design field, the research of the forms and styles of design itself is as an important and too much urgent task as the contents or ideological characters of designeological characters of design

• School Mathematics
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• v.19 no.1
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• pp.171-187
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• 2017

To engineering students, calculus is essential knowledges and skills as a mathematical model and give a perspective to observe phenomenon in the future industrial field. However, engineering students' calculus study tends to solve problems by only applying the mechanical calculation and mathematical results. This study aimed to make engineering students realize the importance of calculus and untypical problems, by suggesting problems that could apply the mathematical concepts and principles and even solve the actual conditions of the problems. Students conjectured the anti-derivative graphs by interpreting the given derivate problems. They showed errors in this process and the errors are contributed by their mathematics leaning styles. As a result, the task would be helpful to engineering students.

• Journal of the Korean Society for Nondestructive Testing
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• v.26 no.6
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• pp.427-439
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• 2006

Accurate estimates of in place thickness of early age (3 to 28 days after casting) concrete pavements are needed, where a thickness accuracy of ${\pm}6mm$ is desired. The impact-echo method is a standardized non-destructive technique that has been applied for this task. However, the ability of impact-echo to achieve this precision goal is affected by Vp (measured) and ${\beta}$ (assumed) values that are applied in the computation. A deeper understanding of the effects of these parameters on the accuracy of impact-echo should allow the technique to be improved to meet the desired accuracy goal. In this paper, the results of experimental tests carried out on a range of concrete slabs are reported. Impact-echo thickness estimation errors caused by material property gradients and sensor type are identified. Correction factors to the standard analysis method are proposed to correct the identified errors and to increase the accuracy of the standard method. Results show that improved accuracy can be obtained in the field by applying these recommendations with the standard impact-echo method.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.34 no.1
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• pp.1-8
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• 2011

Controlling industrial vehicle operated by human in warehouse was not simple since the information transfer for controlling the vehicle was not easy. However, as the technology for the WMS (Warehouse Management System) has been advanced and the PDA (Personal Digital Assistant) has come into wide use in a workplace, the control of man-operated vehicle became less difficult as do to AGVS (Automated Guided Vehicle System). This study examines the ways to improve the efficiency of warehouse operation through introducing rule of task assignment for the vehicles, particularly forklift. This study, basically, refer to AGV operation policy because a great number of studies for AGV dispatching rule have been done and the mechanism for the controlling vehicles is very similar. The workers in field prefer to simple dispatching rules such as Shortest Retrieval Time First (SRTF), Shortest Travel Time First (STTF), and Longest Waiting Time First (LWTF). However, these rules have potential disadvantage. Thus, several rules made up by combining rules mentioned above are introduced and these new rules use threshold value or evaluation formula. The effectiveness of these new rules are tested by simulation and the results are compared. This study proposes favorable dispatching rules for forklift in warehouse for the efficiency of the vehicle operation and stability of service level.