• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.2
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• pp.132-139
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• 1989

We have designed a real-time Cardiac digital substraction angiography system (C-DSA) and tested the system for the diagnosis of Cardiac patients. The system was developed by interfacing a radiographic angiography system to a computerized motional image analysis system. This new cardiac DSA can perform the real time processing of averaging and subtraction of the 32 image frames to measure the volume changes of the left ventricle after elimination of motional artrifacts, caused by the heart contraction of beats per minute in average. Each frame has a resolution of 512 x 512 pixels and 256 gray levels. Two image data with maximal and minimal volume were moved to the interfaced IBM PC computer system by high speed computer link line for computation of the heart's contraction parameters. First, the boundary of the left ventricule was detected using a dynamic programming of the gray levels, and its volume was computered to determine the parameters, such as the maximal volume of end-diastolic volume (EDV), the minimal volume of end systolic volume (ESV), and ejection fraction (EF).

• Journal of Korea Multimedia Society
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• v.20 no.7
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• pp.1038-1045
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• 2017

The increase in frequency and scale of natural disasters is the typical negative examples of the global climate change and the change of the human living environment. The damage caused by natural disasters in particular including human and physical damage is directly linked to the safety and properties of citizens. Besides, damage occurs directly or indirectly to the SOC facility, and the damaged SOC facility violates the citizens' safety rights. Therefore, a plan to provide prompt and effective risk map information by linking a 3D disaster information display system, which handles the information of the damage that may occur to SOC facilities at the time of disasters, with an on-site assistance application is suggested in this study. The prompt provision of risk map information is defined as a dynamic expression technology in this study. It also processes and compresses the system to display disaster information, a spreading system that can utilize on-site information, and a module developed to organically link with the DB system that builds information and relationships. Based on the module, the effective disaster information compression plan will be prepared, and the prompt information transmission system will be secured.

• Journal of Korea Multimedia Society
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• v.9 no.2
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• pp.244-254
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• 2006

This paper presents an efficient hybrid technique to compact the trie indexing the huge forward table small enough to be stored into cache for speeding up IP lookup. It combines two techniques, an encoding scheme called bit-map and a controlled-prefix expanding scheme to replace slow memory search with few fast-memory accesses and computations. For compaction, the bit-map represents each index and child pointer with one bit respectively. For example, when one node denotes n bits, the bit-map gives a high compression rate by consumes $2^{n-1}$ bits for $2^n$ index and child link pointers branched out of the node. The controlled-prefix expanding scheme determines the number of address bits represented by all root node of each trie's level. At this time, controlled-prefix scheme use a dynamic programming technique to get a smallest trie memory size with given number of trie's level. This paper proposes standard that can choose suitable trie structure depending on memory size of system and the required IP lookup speed presenting optimal memory size and the lookup speed according to trie level number.

• The Journal of the Korea Contents Association
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• v.10 no.4
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• pp.397-405
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• 2010

This study proposes visualization methods of the diurnal passenger flows on the Metropolitan Seoul Subway system (MSSs) and examines the passenger trip behaviors of major central business districts (CBDs). We mine the MSS passenger flow information from a single day T-card passenger trip transaction database. It is practically intractable to analyze such flows, involving huge, complex space-time data, by means of general statistical analysis. On the other hand, dynamic visualizations of the passenger flows make it possible to analyze intuitively and to grasp effectively characteristics of the passenger flows. We thus propose several methods to visualize the passenger flow information. In particular, we visualize dynamic passenger flows of each link on the subway network and analyze the time-space characteristics of passenger ridership for the three major CBDs. As the result, we can ascertain the strong association between CBD and subway line and clarify the distinction among three major CBDs in the diurnal patterns of subway passenger flow.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.5
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• pp.575-584
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• 2014

In this study, the NREL 5 MW wind turbine tower model was optimized according to the multi-body dynamics and reliability-based design. The mathematical model was defined as a link-joint system including dynamic characteristics derived from Timoshenko's beam theory. For the optimization problem, the sensitivities to variations in the tower thicknesses and inner and outer diameters were acquired and arranged in terms of safety and efficiency according to bending stress and buckling standards. An optimal design was calculated with the advanced first-order second moment method and used to define a finite element model for validation. The finite element model was simulated by static analysis. The relationship between the multi-body dynamic and finite element method throughout the process was investigated, and the optimal model, which had high endurance despite its low mass, was determined.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.8
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• pp.2894-2909
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• 2015

As the number of mobile devices such as smart phones and tablets explodes, the need for new services or applications is also rapidly increasing. Smart class application is one of the emerging applications, in which most of contents are distributed to all members of a class simultaneously. It is highly required to select relay nodes to cover shadow area of radio as well as extend coverage, but existing algorithms in a smart class environment suffer from high control packet overhead and delay for exchanging topology information among all pairs of nodes to select relay nodes. In addition, the relay selection procedure should be repeated in order to adapt to the dynamic topology changes caused by link status changes or device's movement. This paper proposes the learning based relay selection algorithm to overcome aforementioned problems. The key idea is that every node keeps track of its relay quality in a fully distributed manner, where RQI (Relay Quality Indicator) is newly defined to measure both the ability of receiving packets from content source and the ability of successfully relaying them to successors. The RQI of each node is updated whenever it receives or relays broadcast packet, and the node having the higher RQI is selected as a relay node in a distributed and run-time manner. Thus, the proposed algorithm not only removes the overhead for obtaining prior knowledge to select relay nodes, but also provides the adaptability to the dynamic topology changes. The network simulation and experimental results prove that the proposed algorithm provides efficient and reliable content distribution to all members in a smart class as well adaptability against network dynamics.

• Journal of the Ergonomics Society of Korea
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• v.25 no.3
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• pp.49-60
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• 2006

Technological encroachment provides human operators with flood of information that must be analyzed to understand the environment and make judgments that lead to strategic actions. Further, the environment is not static and therefore uncertain, changing its aspect dynamically. Complexity accompanied with its dynamics imposes substantial difficulty to human operators' task. Criticality of having situational understanding becomes more important than ever. Situationalunderstanding requires the human operators possessing tacit knowledge in order for them to make the sense out of the situation while interacting with information from many heterogeneous sources, the notion of sensemaking. Sensemaking refers to the process of developing mental framework to assemble pieces of information representing different aspects of the environment that can be used to develop one's own actionable knowledge to implement their judgments in the uncertain environment. Therefore, judgment process and performance is a key component of sensemaking process. Among many judgment and decision making models, the lens model with its extension can be utilized to partially describe the judgmental aspect of sensemaking. One of the lens model parameters, unmodeled knowledge, can be a corresponding quantitative measure for the tacit knowledge that plays an important role in sensemaking. In this paper, a comprehensive literature for sensemaking is provided to formally define the notion of sensemaking in the military domain. Also, it is proposed that there is a crucial link between the sensemaking and human judgment process and performance from the lens model perspective. Potential implications for experimental framework are also proposed.

• Journal of Communications and Networks
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• v.13 no.5
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• pp.518-524
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• 2011

A high assurance IP encryption (HAIPE) compliant protocol accelerator is proposed for military networks consisting of red (or classified) networks and black (or unclassified) networks. The boundary between red and black sides is assumed to be protected via a HAIPE device. However, the IP layer encryption introduces challenges for bandwidth on demand satellite communication. The problems experienced by transmission control protocol (TCP) over satellites are well understood: While standard modems (on the black side) employ TCP performance enhancing proxy (PEP) which has been shown to work well, the HAIPE encryption of TCP headers renders the onboard modem's PEP ineffective. This is attributed to the fact that under the bandwidth-on-demand environment, PEP must use traditional TCP mechanisms such as slow start to probe for the available bandwidth of the link (which eliminates the usefulness of the PEP). Most implementations recommend disabling the PEP when a HAIPE device is used. In this paper, we propose a novel solution, namely broadband HAIPE-embeddable satellite communications terminal (BHeST), which utilizes dynamic network performance enhancement algorithms for high latency bandwidth-on-demand satellite links protected by HAIPE. By moving the PEP into the red network and exploiting the explicit congestion notification bypass mechanism allowed by the latest HAIPE standard, we have been able to regain PEP's desired network enhancement that was lost due to HAIPE encryption (even though the idea of deploying PEP at the modem side is not new). Our BHeST solution employs direct video broadcast-return channel service (DVB-RCS), an open standard as a means of providing bandwidth-on-demand satellite links. Another issue we address is the estimation of current satellite bandwidth allocated to a remote terminal which is not available in DVBRCS. Simulation results show that the improvement of our solution over FIX PEP is significant and could reach up to 100%. The improvement over the original TCP is even more (up to 500% for certain configurations).

• The KIPS Transactions:PartD
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• v.11D no.6
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• pp.1327-1334
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• 2004

The purpose of this paper is to implement Web 3D environment that is not provider - oriented but client-oriented in order to provide dynamic information and to analyze knowledges by executing programs on Web pages. For these, The 3D Viewer program that parses and renders ASE files - the most general 3D Model Data file and exported text file of 3D Max Studio - is made and then converted into ActiveX 3D Viewer Component that can be used on the Web. With the purpose of managing ASE and texture file efficiently and interacting between clients and server, ActiveX Component link ASP and Database with Web Service. The 3D View Web Service can make dynamic information and cooperative works easier in Networked Virtual Reality.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.2
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• pp.121-127
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• 2011

This paper presents an autonomous formation flight algorithm for micro aerial vehicles (MAVs) and its flight test results. Since MAVs have severe limits on the payload and flight time, formation of MAVs can help alleviate the mission load of each MAV by sharing the tasks or coverage areas. The proposed formation guidance law is designed using nonlinear dynamic inversion method based on 'Leader-Follower' formation geometric relationship. The sensing of other vehicles in a formation is achieved by sharing the vehicles' states using a high-speed radio data link. the designed formation law was simulated with flight data of MAV to verify its robustness against sensor noises. A series of test flights were performed to validate the proposed formation guidance law. The test result shows that the proposed formation flight algorithm with inter-communication is feasible and yields satisfactory results.