• Journal of Drive and Control
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• v.18 no.2
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• pp.20-31
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• 2021

An excavator is a construction machine that can perform various tasks such as trenching, piping, excavating, slope cutting, grading, and rock demolishing. In the 2010s, unmanned construction equipment using ICT technology was continuously developed. In this paper, the path design process was studied to implement the output data of the decision stage, and the path design algorithm was developed. For example, the output data of the decision stage were terrain data around the excavator, excavator mechanism information, excavator hydraulic information, the position and posture of the bucket at key points, the speed of the desired bucket path, and the required excavation volume. The result of the path design was the movement of the hydraulic cylinder, boom arm, bucket, and bucket edge. The core functions of the path design algorithm are the function of avoiding impact during the excavation process, the function to calculate the excavation depth that satisfies the required excavation volume, and the function that allows the bucket to pass through the main points of the excavation process while maintaining the speed of the desired path. In particular, in the process of developing the last function, the node tracking method expressed in the path design table was newly developed. The path design algorithm was verified as this path design satisfied the JCMAS H02 requirement.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.1
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• pp.98-106
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• 1991

Future generation of robots will be considerably more autonomous than present robotic systems. The main objective of research on theoretical problems in robotics is to endow robotics system with basic capabilities they will need to operate in an intelligent and autonomous manner. This paper discusses the problem of collision free movement of robot manipulator. It is formulated in path planning with obstacle avoidance expressed in the term of the distance between convex shapes in the three dimensional space. The examples are given to illustrate the main feature of the method.

• Journal of the korean society of oceanography
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• v.37 no.3
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• pp.196-200
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• 2002

The time variation in the Kuroshio is studied by use of nine observed distances of the main Kuroshio axis from the Japanese coast. The observed distances over 1975 - 1995 are estimated from the Prompt Report of Oceanographic Conditions published by Hydrographic Department of the Maritime Safety Agency of Japan. It is shown that large sea level difference between Naze and Nishinoomote, which represents the volume transport of the southern inflow south of Kyushu, coincides with larger distance of the Kuroshio in the upstream area from off Kyushu to off eastern Kii Peninsula and smaller distance in the downstream area from off Omae-zaki to off Boso Peninsula. In contrast, large sea level difference between Nishinoomote and Aburatsu, which represents the volume transport of northern inflow south of Kyushu, corresponds to smaller distance in the upstream area and larger distance in the downstream area. Path dynamics of the Kuroshio is discussed with reference to the variation in Volume transport south of Kyushu.

• Journal of the military operations research society of Korea
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• v.17 no.2
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• pp.72-89
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• 1991

In transportation network problems, it is often desirable to select multiple number of the shortect paths. On problems of finding these paths, algorithms have been developed to choose single shortest path, k-shortest paths and k-shortest paths via p-specified nodes in a network. These problems consider the time as the main factor. In wartime, we must consider availability as well as time to determine the shortest transportation path, since we must take into account enemy's threat. Therefore, this paper addresses the problem of finding the shortest transportation path considering both time and availability. To accomplish the objective of this study, values of k-shortest paths are computed using the algorithm for finding the k-shortest paths. Then availabilties of those paths are computed through simulation considering factors such as rates of suffering attack, damage and repair rates of the paths. An optimal path is selected using any one of the four decision rules that combine the value and availability of a path.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1046-1050
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• 2003

In this paper, we describe study on the development or multi-path ultrasonic gas flowmeter using a transit time method. This system includes 5 pairs of ultrasonic transducers. ultrasonic signal processing unit using switch matrix method, computation algorithm of gas flow rate, spool piece type multi-path pipe unit. We have developed enhanced type of main ultrasonic signal processing unit using switch matrix method fer multi-path ultrasonic gas flowmeter. Also, we have developed the new transmitting ＆ receiving method of ultrasonic waves and the new signal processing algorithm for the computation of ultrasonic transit time from received ultrasonic waves. In this study, we have designed more compact signal processing unit compared with the conventional hardware system of multi-path ultrasonic gas flowmeter. We have confirmed its reliability for multi-path ultrasonic gas flowmeter through the laboratory test using calibration system. In the future. we will perform the field test for the developed system in the POSCO gas line.

• Steel and Composite Structures
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• v.27 no.1
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• pp.13-25
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• 2018

The main objective of this study is to develop a dual approach for geometrically nonlinear finite element analysis of plane truss structures. The geometric nonlinearity is considered using the Total Lagrangian formulation. The nonlinear solution is obtained by introducing and minimizing an objective function subjected to displacement-type constraints. The proposed method can fully trace the whole equilibrium path of geometrically nonlinear plane truss structures not only before the limit point but also after it. No stiffness matrix is used in the main approach and the solution is acquired only based on the direct classical stress-strain formulations. As a result, produced errors caused by linearization and approximation of the main equilibrium equation will be eliminated. The suggested algorithm can predict both pre- and post-buckling behavior of the steel plane truss structures as well as any arbitrary point of equilibrium path. In addition, an equilibrium path with multiple limit points and snap-back phenomenon can be followed in this approach. To demonstrate the accuracy, efficiency and robustness of the proposed procedure, numerical results of the suggested approach are compared with theoretical solution, modified arc-length method, and those of reported in the literature.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.04a
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• pp.123-127
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• 2004

The present system of medium and large size ship when that's ship came alongside the pier, are not systemic. The steersman only depend on radio-communication, not visuality. This treatise bridge a gap of current system from development of simulation program The main-server get a distance from ship to peer and ship's direction using longitude and latitude, heading, rate. The steersman of main ship and tug will see all situation with PDA client program. The PDA client program directly display a location information from main-server. And ship's most suitable path be calculated simulation program using database system. This method will induce more detail situation information and the most suitable path when the ship coming alongside the pier.

• Journal of Intelligence and Information Systems
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• v.25 no.3
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• pp.179-200
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• 2019

Word-of-mouth (WoM) is defined by consumer activities that share information concerning consumption. WoM activities have long been recognized as important in corporate marketing processes and have received much attention, especially in the marketing field. Recently, according to the development of the Internet, the way in which people exchange information in online news and online communities has been expanded, and WoM is diversified in terms of word of mouth, score, rating, and liking. Social media makes online users easy access to information and online WoM is considered a key source of information. Although various studies on WoM have been preceded by this phenomenon, there is no meta-analysis study that comprehensively analyzes them. This study proposed a method to extract major researches by applying text mining techniques and to grasp the main issues of researches in order to find the trend of WoM research using scholarly big data. To this end, a total of 4389 documents were collected by the keyword 'Word-of-mouth' from 1941 to 2018 in Scopus (www.scopus.com), a citation database, and the data were refined through preprocessing such as English morphological analysis, stopwords removal, and noun extraction. To carry out this study, we adopted main path analysis (MPA) and word co-occurrence network analysis. MPA detects key researches and is used to track the development trajectory of academic field, and presents the research trend from a macro perspective. For this, we constructed a citation network based on the collected data. The node means a document and the link means a citation relation in citation network. We then detected the key-route main path by applying SPC (Search Path Count) weights. As a result, the main path composed of 30 documents extracted from a citation network. The main path was able to confirm the change of the academic area which was developing along with the change of the times reflecting the industrial change such as various industrial groups. The results of MPA revealed that WoM research was distinguished by five periods: (1) establishment of aspects and critical elements of WoM, (2) relationship analysis between WoM variables, (3) beginning of researches of online WoM, (4) relationship analysis between WoM and purchase, and (5) broadening of topics. It was found that changes within the industry was reflected in the results such as online development and social media. Very recent studies showed that the topics and approaches related WoM were being diversified to circumstantial changes. However, the results showed that even though WoM was used in diverse fields, the main stream of the researches of WoM from the start to the end, was related to marketing and figuring out the influential factors that proliferate WoM. By applying word co-occurrence network analysis, the research trend is presented from a microscopic point of view. Word co-occurrence network was constructed to analyze the relationship between keywords and social network analysis (SNA) was utilized. We divided the data into three periods to investigate the periodic changes and trends in discussion of WoM. SNA showed that Period 1 (1941~2008) consisted of clusters regarding relationship, source, and consumers. Period 2 (2009~2013) contained clusters of satisfaction, community, social networks, review, and internet. Clusters of period 3 (2014~2018) involved satisfaction, medium, review, and interview. The periodic changes of clusters showed transition from offline to online WoM. Media of WoM have become an important factor in spreading the words. This study conducted a quantitative meta-analysis based on scholarly big data regarding WoM. The main contribution of this study is that it provides a micro perspective on the research trend of WoM as well as the macro perspective. The limitation of this study is that the citation network constructed in this study is a network based on the direct citation relation of the collected documents for MPA.

• 전기의세계
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• v.26 no.4
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• pp.54-60
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• 1977

The feedback sources of oculomotor control system consist of three types of feedback path originating from retinal image displacement, in the proprioceptive fibers of the extraocular muscles, in the efference copy within the C.N.S. From above feedback loops, the retinal image feedback path is a main subject in this experiment. The electrical output of eye ball motion detecting with a photo-electric matrix method is fed into galvanometer through the external feedback path, and the stability was also examined.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.10
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• pp.34-39
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• 2010

We developed a path algorithm for ultrafast/wide area laser processing. Demands for high precision laser processing with a wide area has been increasing for a number of applications such as in solar cell battery, display parts, electronic component and automobile industry. Expansion of the area in which laser processing is an important factor to handle the ultrafast/wide area processing, it will require a processing path. Processing path is path of 2- axis stage and stage of change in velocity can be smooth as possible. In this paper, we proposed a smoothingnurbs method of improved speed profile. This method creates soft path from edge part, it is main purpose that scan area ($50mm{\times}50mm$) inside processing path makes path of topology of possible straight line. We developed a simulation tool using Visual C++.