• International Journal of Highway Engineering
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• v.1 no.2
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• pp.135-154
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• 1999

Compaction of asphalt pavement is one of the important processes to make good quality one. There are many laboratory-compaction methods to simulate field compaction, including Marshall compaction, Hveem compaction, gyratory compaction, and etc. The most common method used to determine the fundamental properties of asphalt mixture for design is Marshall method which is using impact energy. However, there is major difference between field compaction using kneading compaction and Marshall compaction using impact energy. Therefore, the gyratory compactor, which currently is the best to simulate the field compaction, was employed. The fundamental properties of asphalt specimen compacted by gyratory compactor and Marshall compactor were determined using laboratory test. From the tests, slag mixture with carbon black or pyrolyzed carbon black showed better performances, such as, in low susceptibility to temperature, high resistance against water and rutting, and high resilient modulus and indirect tensile strength.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.662-665
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• 2004

In this paper, based on shaking table test results on a seismically isolated bridge model, an inelastic numerical model is refined by using Bouc-Wen model representing the hysteretic behavior of isolators. Seismic responses of isolated bridges are numerically investigated varying with relative stiffness ratios, which is a ratio of the effective stiffness of isolator to the lateral stiffness of bridge pier. From the results, it is found that an adequate range of relative stiffness ratio could be defined for seismic design of isolated bridges without considering the flexibility of piers.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.11a
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• pp.737-741
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• 2000

Portable communication devices such as laptop computers suffer impact-induced failure in their usage. Drop/impact performance of these products is one of important concerns of product design. Because of the small size of this kind of electronics products, it is very expensive, time-consuming and difficult to conduct drop tests to directly detect the failure mechanism and identify their drop behaviors. Finite element analysis provides a vital, powerful vehicle to solve the problems. The models are created with HYPERMESH, and the analysis is carried out with LS-DYNA3D. The analysis is focused on HDD impact behavior in acceleration peak values.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.1
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• pp.46-63
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• 2012

The concept of an "intelligent building" received significant attention from academic, industry and standard development organizations when technically termed a building management system (BMS). Wireless sensor networks (WSNs) and their recent development enhanced monitoring and control applications for the building's areas. This paper surveys and analyzes advantages of the main current and emerging approaches that may be fit for BMS. Specifically, we discuss challenges including interoperability, integration, overhead, and bandwidth limitation of WSNs in BMS. Based on analyses, we highlight the advantages of an IP-based and RESTful architecture approach as the most suitable solution for BMS using WSNs (BMS-WSN). The paper also describes our future direction and design for BMS-WSN based on these advantages. The purpose is to enable interaction of users with BMS-WSN in the same way as with any website while ensuring energy efficiency. A test-bed implementation and evaluation of a BMS application is also introduced in this paper to demonstrate the feasibility and benefits of IP-based and RESTful architecture for BMS.

• Journal of Power Electronics
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• v.19 no.6
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• pp.1544-1553
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• 2019

The efficiency of photovoltaic generation systems depends on the maximum power point tracking (MPPT) technique. Among the various schemes presented in the literature, the incremental conductance (INC) method is one of the most frequently used due to its superb tracking ability under changes in insolation and temperature. Generally, conventional INC algorithms implement a simple duty-cycle updating rule that is mainly found on the polarity of the peak-power evaluation function. However, this fails to maximize the performance in both steady-state and transient conditions. In order to overcome this limitation, a novel regulated INC (r-INC) method is proposed in this paper. Like the compensators in automatic control systems, this method applies a digital compensator to evaluate the INC function and improve the capability of power tracking. Precise modeling of a new MPPT system is also presented in the optimized design process. A 120W boost peak power tracker is utilized to obtain comparative test results and to confirm the superiority of the proposed method over existing techniques.

• Journal of Positioning, Navigation, and Timing
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• v.10 no.4
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• pp.253-262
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• 2021

Global Navigation Satellite Systems (GNSS) based precise positioning using Real Time Kinematic (RTK) technique has been proposed as an enabler of the formation operation of moving vehicles. In RTK methods, the integer ambiguity of GNSS carrier phase measurements must be resolved. Although there have been many proposed algorithms for the integer ambiguity resolution, the widelane combination of carrier phase measurements and LAMBDA methods have gained the most popularity in literatures when dual frequency GNSS measurements were used. In this paper, we evaluated five alternative methods to determine relative positions of moving base and rover receivers; the round-off scheme of widelane carrier phase, instant least-squares and Kalman filter-based LAMBDA with widelane carrier phase, instant least-squares and Kalman filter-based LAMBDA with dual frequency measurements. The paper presented the performance of each method using flight test data, which showed their strength and weakness in the aspects of time-to-first-fix, ambiguity resolution success ratio, and relative position errors. Based on that, we provided practical recommendations of RTK operations for moving vehicles.

• KEPCO Journal on Electric Power and Energy
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• v.7 no.1
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• pp.85-91
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• 2021

With the social atmosphere of respect for human life and the increasing interest in safety of field workers, research and development is underway in various ways to transform direct live method into indirect live method in the field of distribution. As part of this measure, it was necessary to convert electric pole and complex facilities work from machining power distribution to indirect live operation, and install a straight connecting sleeve that connects cut wires for by-pass method, but it failed to meet the tensile strength standard when constructing a sleeve constructed by direct method. In this paper, the design factors were derived based on the case of overseas similar sleeves and the tensile strength evaluation of each variable was performed, based on the analysis of these test results, the method for securing tensile strength of straight-line access sleeves for indirect running was presented.

• International Journal of Computer Science & Network Security
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• v.22 no.12
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• pp.239-244
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• 2022

The study aimed to build a program in activities for early childhood students to develop some of the basic skills necessary for the age of artificial intelligence, to achieve the objectives of the study , the researcher used the experimental design, and the research sample consisted of 37 early childhood students. The study used the following tools: Experimental treatment subject: the proposed program in the activities, Measurement and evaluation tool: testing the basic skills needed for the age of artificial intelligence. The study concluded several results: There is a statistically significant difference (α≤0.05) between the average grades of the early childhood students in the research group in the tribal and remote measurements to test the basic skills necessary for the age of artificial intelligence in favor of the students grades in the dimensional measurements. Practical application of the study through benefiting from the proposed program of activities prepared in the current study in planning and implementing activities to develop the basic skills necessary for the age of artificial intelligence among early childhood students.

• ETRI Journal
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• v.45 no.3
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• pp.479-491
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• 2023

The automation of agricultural machines is an irreversible trend considering the demand for improved productivity and lack of labor in handling agricultural tasks. Unstructured working environments and weather often inhibit a seemingly simple task from being fully autonomously performed. In this context, we propose a remote driving system (RDS) to aid agricultural machines designed to operate autonomously. Particularly, we modify a commercial speed sprayer for orchard environments into a robotic speed sprayer to evaluate the proposed RDS's usability and test three sensor configurations in terms of human performance. Furthermore, we propose a confidence error ellipsebased task performance measure to evaluate human performance. In addition, we present field experimental results describing how the sensor configurations affect human performance. We find that a combination of a semiautonomous line tracking device and a wide-angle camera is the most effective for spraying. Finally, we discuss how to improve the proposed RDS in terms of usability and obtain a more accurate measure of human performance.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.2A
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• pp.179-186
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• 2008

To analyzing the validity for using the stiffness ratio in evaluating edge stiffness effect of the composite girder bridges, modification factors are analyzed with changing girder spacing. The relation between stiffness ratio, loading type, girder spacing and modification factors is analyzed. From the results of comparing modification factors analyzed from the field loading test and the established design method with the modification factor analyzed from this study, it was concluded that evaluating the edge stiffness effect using stiffness ratio is possible.