• Journal of the Ergonomics Society of Korea
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• v.18 no.3
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• pp.127-140
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• 1999

In order to apply three-dimensional images to industries, the possibility of realizing three-dimensional images should be ensured and when operating a task using three-dimensional images, the intention of the observer and the result of operation should be precisely related. The aim of this paper is to investigate the task performance of a human operator during operating a robot manipulator using three-dimensional and two-dimensional image displays. From the result of this research, it was found that the accuracy of robot operation in the case of using three-dimensional displays is much higher than in the case of using two-dimensional displays and the adapting time to the operating task using three-dimensional displays is shorter than that using two-dimensional displays. From such results, we concluded that the application of three-dimensional displays, which can closely reflect real environment, to industries is desirable.

• Journal of Information Processing Systems
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• v.13 no.5
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• pp.1259-1276
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• 2017

As technologies related to sensor network are currently emerging and the use of GeoSensor is increasing along with the development of Internet of Things (IoT) technology, spatial query processing systems to efficiently process spatial sensor data are being actively studied. However, existing spatial query processing systems do not support a spatial-temporal data type and a spatial-temporal operator for processing spatialtemporal sensor data. Therefore, they are inadequate for processing spatial-temporal sensor data like GeoSensor. Accordingly, this paper developed a spatial-temporal query processing system, for efficient spatial-temporal query processing of spatial-temporal sensor data in a sensor network. Lastly, this paper verified the utility of System through a scenario, and proved that this system's performance is better than existing systems through performance assessment of performance time and memory usage.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1993.10a
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• pp.666-675
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• 1993

In order to prevent bodily injuries frequently suffered in using bush cutters, especially from spattered stones, we developed a unique new cutting system equipped with a fixed blade on top of the rotary blade, and checked into the mowing performance of the cutter. From experimental test of mowing efficiency and measuring test of physical stress (O$_2$ consumption and heartbeat rates) , the new cutting system with a fixed blade proved that it keeps good cutting performance with lower peripheral speed of the rotary blade(22m/sec), compared to that of ordinary cutting blade, yielding more safety in operation. Weight of the cutter head is, however, heavier than that of ordinary machine by about 70% which increased a physical stress on the operator with slightly faster heartbeat rates. In mowing along edge of concrete wall, the operator enjoyed using the cutter with no anxiety , owing to function of the fixed blade.

• Journal of the Ergonomics Society of Korea
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• v.32 no.1
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• pp.37-45
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• 2013

Objective: This study describes the change of operator performance in drastic change of illumination level, and proposes an alternative method to cope with it. Background: The control standard of illumination for nuclear power plants(NPPs) is based on the set of limit criteria for maintaining a specific illumination level. However, there is a possibility to cause human errors according to the psychological and physiological influences to operators in the situation of drastic change of illumination such as SBO(Station Black Out), so a basic study is necessary to review the current approach. Method: We assessed the visual fatigue, subjective work load and task performance according to the three illumination situations(Normal Illumination, Emergency Illumination, and Drastic Change of Illumination). Result: Research finding shows that there are not significant differences in task performance between normal illumination (1,000lx level) and emergency illumination (100lx level), only if beyond the dark adaptation limit. However, subjective work load on mental demand and visual fatigue show a potential challenge to visual performance in drastic change of illumination. Conclusion/Application: Several trials can complement this challenge in NPPs by applying 3-way communication, enhancing readability of procedures, and managing the visual factors affecting the operators' performance through a Visual Environment Management Program including visual health aspects, etc.

• 한국전산유체공학회:학술대회논문집
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• 2004.10a
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• pp.73-77
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• 2004

In the present study, an efficient and robust implicit operator for the LU-SGS method is proposed. Numerical experiments for supersonic flow are performed to demonstrate the performance of the proposed method.

• Journal of Ocean Engineering and Technology
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• v.33 no.6
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• pp.620-626
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• 2019

With the development of robot technology, the expectation of autonomous mission operations has increased, and the research on robot control architectures and mission planners has continued. A scalable and robust control architecture is required for unmanned surface vehicles (USVs) to perform a variety of tasks, such as surveillance, reconnaissance, and search and rescue operations, in unstructured and time-varying maritime environments. In this paper, we propose a robot control architecture along with a new utility function that can be extended to various applications for USVs. Also, an additional structure is proposed to reflect the operator's command and improve the performance of the autonomous mission. The proposed architecture was developed using a robot operating system (ROS), and the performance and feasibility of the architecture were verified through simulations.

• Proceedings of the Korean Nuclear Society Conference
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• 1995.10a
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• pp.254-259
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• 1995

Large scale display panel(LSDP) is a main component in the next generation main control rooms. LSDP is located at the front of VDU-based operator's workstation and plays an important role in providing operators with overall information of plant status through mimic diagram, text/digit, graph, and so on. A critical matter determined at the first stage of LSDP design is how much information is displayed, because the information density of LSDP affects operator's performance. Many human factors guidelines recommend low information density of displays to avoid degrade of operator's performance, but doesn't provide a useful limit of information density. In this paper, we considered information density as the number of plant parameters and investigated the proper number of plant parameters through a human factors experiment. The experiment with 4 subjects was carried out and response time, error, and heart rate variation as criterion measures were recorded and analyzed. As the results, it is identified that the proper number of parameters in a LSDP is about thirty.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1759-1764
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• 2005

Human Adaptive Mechatronics(HAM) is a new concept which was proposed in our university's research project sponsored by Japanese Ministry of Education, Sports, Culture, Science and Technology(MEXT), and is defined as "intelligent mechanical systems that adapt themselves to the user's skill under various environments, assist to improve the user's skill, and assist the human-machine system to achieve best performance". In this paper, the concept and key-items of HAM are mentioned. And the control strategy to realize a HAM human-machine system is explained in the case of physical-interface system, i.e. haptic system. The proposed assist-control of a force-feedback type haptic system includes online estimation of a operator's control characteristics, and a `force assist' function implemented as a change in the support ratio according to the identified skill level. We developed a HAM-haptic device test system, executed evaluation experiments with this apparatus, and analyzed the measured data. It was confirmed that the operator's skill could be estimated and that operator's performance was enhanced by the assist-control.

• Nuclear Engineering and Technology
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• v.44 no.8
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• pp.911-918
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• 2012

Steam generator level control at low power is difficult due to its adverse thermal hydraulic properties, and is usually conducted by an operator. The basic model predictive control (MPC) is similar to the action of an operator in that the operator knows the desired reference trajectory for a finite period of time and takes the necessary control actions needed to ensure the desired trajectory. An MPC is based on a model; the performance as well as the efficiency of the MPC depends heavily on the exactness of the model. In this study, steam generator models that can describe in detail its thermal hydraulic behaviors, particularly at low power, are used in the MPC design. The design scope is divided into two parts. First, the MPC feedwater controller of the feedwater station is determined, and then the MPC level controller for the overall system is designed. Because the dynamic properties of a steam generator change with the power levels, a realistic situation is simulated by changing the transfer functions of the steam generator at every time step. The resulting MPC controller shows good performance.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.8
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• pp.1161-1167
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• 2015

Distribution Management System(DMS) ienhancing distribution automation system-based operation efficiency is an optimized system by various operational applications in a distribution network. DMS employs various applications like topology reconfiguration, volt/var control, and restoration at events such as overload, voltage violation, and a fault in a distribution system. An operation efficiency to employ multi-applications as restoration with short-term load forecasting is higher than a performance by a single application; and the applications are accomplished by an operator’s control. Applications’ combination is determined by various alarm information which means critical issues in order to operate a distribution system. Thus, this paper proposes an application management system which can configure application combination, control applications depending on alarm information and check their performance condition. The proposed application management system can be customized by operator easily and have high operation efficiency and reliability because it is worked by reviewed alarm information from operator.