• Journal of Advanced Marine Engineering and Technology
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• v.40 no.10
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• pp.906-915
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• 2016

In this study, a network monitoring system, including a secure 460-Network and a 460-Gateway, is designed and developed according with the requirements of the IEC (International Electro-Technical Commission) 61162-460 network standard for the safety and security of networks on board ships. At present, internal or external unauthorized access to or malicious attack on a ship's on board systems are possible threats to the safe operation of a ship's network. To secure the ship's network, a 460-Network was designed and implemented by using a 460-Switch, 460-Nodes, and a 460-Gateway that contains firewalls and a DMZ (Demilitarized Zone) with various application servers. In addition, a 460-firewall was used to block all traffic from unauthorized networks. 460-NMS (Network Monitoring System) is a network-monitoring software application that was developed by using an simple network management protocol (SNMP) SharpNet library with the .Net 4.5 framework and a backhand SQLite database management system, which is used to manage network information. 460-NMS receives network information from a 460-Switch by utilizing SNMP, SNMP Trap, and Syslog. 460-NMS monitors the 460-Network load, traffic flow, current network status, network failure, and unknown devices connected to the network. It notifies the network administrator via alarms, notifications, or warnings in case any network problem occurs. Once developed, 460-NMS was tested both in a laboratory environment and for a real ship network that had been installed by the manufacturer and was confirmed to comply with the IEC 61162-460 requirements. Network safety and security issues onboard ships could be solved by designing a secure 460-Network along with a 460-Gateway and by constantly monitoring the 460-Network according to the requirements of the IEC 61162-460 network standard.

• Proceedings of the SAREK Conference
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• 2008.11a
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• pp.21-26
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• 2008

Recently, small and medium-sized buildings have employed a multi-heat pump. The major benefits of the multi-heat pump over a conventional system are that it is easier system to maintain along with a diversification of facility use, and high comfortability. The performance of multi-heat pump systems can be enhanced by using geothermal energy instead of air source energy. This paper describes the multi-heat pumps applied in an ground source heat pump system for an actual building. The performance of a ground source multi-heat pump installed in the field was investigated in cooling mode. The maximum COP of the systems with single U-tube and double tube ground loop heat exchangers were 6.6 and 6.0, respectively. It is suggested that the new algorithms to control the flow rate of secondary fluid for ground loop heat exchanger have to be developed in order to enhance the performance of the system.

• Journal of the Korean Association of Geographic Information Studies
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• v.14 no.2
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• pp.128-137
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• 2011

The purpose of the FAPIS(Forest Aerial Photograph Interpretation System) development is to increase accuracy and efficiency of the digital forest cover type mapping for improving conventional analog-based mapping procedures by optimizing work-flow and mapping technology. The database models including digital forest cover type map, aerial photograph, and topographic map were designed for use in this system construction. The interface configured concisely to connect with functions such as search engine, display control, conversion to stereo interpretation mode, modification tools, automation of print layout and database models. It is expected that the standardization methodology based on this system can be applied and extended in making all kinds of digital thematic maps, providing decision-making and information of forest resources.

• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.1
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• pp.64-77
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• 2020

An electric-pump cycle, which is a propellant supply system for driving pumps of a liquid rocket engine using an electric motor, has the advantages of simple system configuration and easy control of supply flow rate and pressure. This paper investigates and analyzes the overseas research trends of the electric-pump cycle. In addition, the research and development country, performing organization, application, engine thrust, pump pressure increase, motor power, and rotation speed are summarized. Among them, the design variables of the overseas research that applied the upper-stage propulsion system with the thrust range of 0.445~2.2 kN could be used in the study of a similar electric-pump cycle in Korea.

• Journal of Sensor Science and Technology
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• v.30 no.2
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• pp.109-113
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• 2021

In this study, an automated culture media replacement system was developed to analyze changes in the contraction characteristics of cardiomyocytes according to the state of the culture media. For the long-term storage of culture media, a Peltier refrigerator with a temperature of 5 to 8℃ was provided and a pH of 7.4 was maintained. The cell culture media of the cardiomyocytes was continuously replaced using interlocking pumps at a flow rate of 0.83 μl/h. The cardiomyocytes in which the culture media was replaced automatically demonstrated lower heartbeats per minute compared to samples in which there was no replacement. However, these cardiomyocytes moved more uniformly and produced greater displacement in one heartbeat cycle. It was observed that the sarcomere length of the cardiomyocytes increased due to the automated culture media replacement system. These cardiomyocytes were found to demonstrate better maturation compared to the control group. The maturation of cardiomyocytes was verified through staining images. The proposed automated culture media replacement system generates a uniform heart rate and improvements in contraction force. Based on the study, patient-specific drug toxicity assessments can be conducted using differentiated cardiomyocytes in induced pluripotent stem cells.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.6
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• pp.1045-1054
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• 2020

In this paper, we designed a TCP/IP based ring buffer system that can stably transfer bulk data streams in the unstable network environments. In the scheme we proposed, The observation data stream generated and output by each radio observatory's backend system as a UDP frame is stored as a UDP packet in a large capacity ring buffer via a socket buffer in the client system. Thereafter, for stable transmission to the remote destination, the packets are processed in TCP and transmitted to the socket buffer of server system in the correlation center, which packets are stored in a large capacity ring buffer if there is no problem with the packets. In case of errors such as loss, duplication, and out of order delivery, the packets are retransmitted through TCP flow control, and we guaranteed that the reliability of data arriving at the correlation center. When congestion avoidance occurs due to network performance instability, we also suggest that performance degradation can be minimized by applying parallel streams.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.3
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• pp.205-209
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• 2016

The flowfield characteristics of a square prism having a small triangular prism at the upstream side were investigated by visualizing the flow field using PIV. The ratio of the width of the triangular prism to that of the square prism and the gap ratios between the square and triangular prisms were selected as the experimental parameters. The results are summarized as follows. The Strouhal number measured on the wake side of the square prism, which had the same characteristics as the drag reduction rate, increased, and then decreased with the gap ratio for the same width ratio. For a square prism having a small triangular prism, the stagnation regions were represented at the upstream and downstream sides of the square prism. The size of the stagnation region increased with the width ratio at the upstream side of the square prism, and decreased at the downstream side.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1859-1864
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• 2004

An effective methodology is reported for the optimal design of multisite batch production/transportation and storage networks under uncertain demand forecasting. We assume that any given storage unit can store one material type which can be purchased from suppliers, internally produced, internally consumed, transported to or from other plant sites and/or sold to customers. We further assume that a storage unit is connected to all processing and transportation stages that consume/produce or move the material to which that storage unit is dedicated. Each processing stage transforms a set of feedstock materials or intermediates into a set of products with constant conversion factors. A batch transportation process can transfer one material or multiple materials at once between plant sites. The objective for optimization is to minimize the probability averaged total cost composed of raw material procurement, processing setup, transportation setup and inventory holding costs as well as the capital costs of processing stages and storage units. A novel production and inventory analysis formulation, the PSW(Periodic Square Wave) model, provides useful expressions for the upper/lower bounds and average level of the storage inventory. The expressions for the Kuhn-Tucker conditions of the optimization problem can be reduced to two sub-problems. The first yields analytical solutions for determining lot sizes while the second is a separable concave minimization network flow subproblem whose solution yields the average material flow rates through the networks for the given demand forecast scenario. The result of this study will contribute to the optimal design and operation of large-scale supply chain system.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2010.04a
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• pp.387-388
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• 2010

An open water rudder test was carried out to figure out the flow characteristics around a twin rudder at $Re=1.5\times10^4$. In the analysis, the unique characteristics of a twin rudder, which effects rudder farces, were explained. The analysis is included varying angles of attack fram 10 to 30 degree. In this paper, the measured results has been compared with each other to predict the performance characteristics of a twin rudder's 2-dimensional section by 2-frame grey level cross correlation PIV method. The side force of the rudder could be mainly improved at 0.75L.

• Journal of Korea Society of Industrial Information Systems
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• v.17 no.4
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• pp.51-59
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• 2012

Recently, the study about object tracking using image processing has been active in the field of security and surveillance. Existing security and surveillance systems using multiple cameras have been operating independently. Thus, the chase was difficult when the tracking object move to other monitored areas. In this paper, we propose the way to change the control of camera automatically following the moving direction of objects in multiple cameras. The proposed method detects the object and tracks the object using color information and direction information of object. The color information obtains using the hue and the direction information obtains using the optical flow. At this time, the optical flow is detected for the entire image area of an object that is not applied only to reduce the computational complexity makes it possible to track in real time. In addition, it can be solved to inconvenience of security surveillance system to use existing camera by tracking an object automatically.