• The Journal of the Acoustical Society of Korea
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• v.11 no.2
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• pp.59-67
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• 1992

Recently, the problem which actively control the unwanted noise propagated from the technical structure by the generated secondary sound has become considerable topic from the environmental preservation point of view. In most of these studies, active noise control deals with a plane wave propagation at low frequency using adaptive filtering techniques. On the other hand, in real acoustic systems are mostly short due to the limitation of geometric configuration. In this case, the acoustic properties such as reflections and resonances inside the acoustic system should be considered. In this paper, the acoustic modeling method for short length duct was introduced using the transfer matrix method, and the active noise control problem was investigated with \implementation of FIR filter for the transfer function of control system derived from this modeling method. The identification methods for the acoustic model of actual control system was proposed by numerical computation technique based on the estimation of optimal FIR filter coefficients. The acceptable attenuation on the real acoustic system and stability of the controller are predicted in this computational simulation.

• Journal of the HCI Society of Korea
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• v.1 no.1
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• pp.29-36
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• 2006

Tactile displays can provide useful information without disturbing others and are particularly useful for people with visual or auditory impairments. They can also complement other displays. In this paper, we present a new vibrotactile display device for wearable, mobile, and ubiquitous computing environments. The proposed vibrotactile device has a $5{\times}5$ array configuration for displaying complex information such as letters, numbers, and haptic patterns as well as simple directional ques and situation awareness alarms. Commercially available coin-type vibration motors are embedded vertically in flexible mounting pads in order to best localize vibrations on the skin. An embedded microprocessor controls the motors sequentially with an advanced tracing mode to increase recognition rate. User studies with the vibrotactile device on the top of the foot show 86.7% recognition rate for alphabet characters after some training. In addition, applying vibrotactile device to driving situation shows 83.9% recognition rate. We also propose some potentially useful application scenarios including Caller Identification for mobile phones and Navigation Aids for GPS systems while driving.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.8
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• pp.1615-1622
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• 2016

This research aims to develop a voyage performance monitoring system based on international standards. The developed system is equipped with an electronic navigational chart(ENC) that provides onshore and offshore information, as well as supports standardized interfaces with navigational equipment, such as a gyro compass, a differential global positioning system(DGPS), and an automatic identification system(AIS), to monitor the navigation route in real time. In addition, the proposed system adopts a car navigation system to provide a graphical user interface, an intuitive menu-driven configuration, and an easy guide for safer sea navigation. The system, interfaced with the gyro compass and DGPS, was verified without any data loss, and passed a test conducted under extreme conditions by the Korea Laboratory Accreditation Scheme(KOLAS). Finally, the system contributes to preventing collision of vessels and minimizing casualties by maximizing the convenience of mariners which a conventional system does not provide.

• Korean Journal of Materials Research
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• v.26 no.11
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• pp.656-661
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• 2016

4H- and 6H-SiC grown by physical vapor transport method were investigated by transmission electron microscopy (TEM). From the TEM diffraction patterns observed along the [11-20] zone axis, 4H- and 6H-SiC were identified due to their additional diffraction spots, indicating atomic stacking sequences. However, identification was not possible in the [10-10] zone axis due to the absence of additional diffraction spots. Basal plane dislocations (BPDs) were investigated in the TEM specimen prepared along the [10-10] zone axis using the two-beam technique. BPDs were two Shockley partial dislocations with a stacking fault (SF) between them. Shockley partial BPDs arrayed along the [0001] growth direction were observed in the investigated 4H-SiC. This arrayed configuration of Shockley partial BPDs cannot be recognized from the plan view TEM with the [0001] zone axis. The evaluated distances between the two Shockley partial dislocations for the investigated samples were similar to the equilibrium distance, with values of several hundreds of nanometers or even values as large as over a few micrometers.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.10B
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• pp.857-865
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• 2006

In order to test and evaluate the various functions and services of NGN would be promised, a specified methodology is needed and a development for the identification of testing object, configuration and test traffic are required. Simulation and analytical modeling methodshave used for IP performance testing, but further study issue still remains. This paper proposes new evaluation methodology to achieve an objective approach rather than a subjective and isolated, based on the real-field environment, for NGN network. For this purpose, background traffic pattern to interfere test traffic was specified and it was tested in actual NGN testbed with systems having NGN technology, such as per bandwidth and packet size. The results shows the suggested methodology is appropriate, comparing with parameters which are Delay, Jitter and Loss the current approach for the end-to-end performance evaluation on NGN.

• International Journal of High-Rise Buildings
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• v.6 no.2
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• pp.149-163
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• 2017

With the intensification of urban development in Chinese cities, mixed land use in urban centers extends vertically into 3-D and expands its scale from a single building to commercial clusters. The multi-level pedestrian system in city centers also changed its role from one of traffic isolation to spatial integration, where transit nodes, street sidewalks, squares, building entrances, atriums, and corridors are interconnected, both horizontally and vertically, into a whole spatial system, within which pedestrian flows are guided and shopping facilities are arranged. This paper uses spatial configuration analysis of space syntax to examine the impacts of spatial patterns on movement distribution and the business performance of tenant mix in the multi-level commercial system of the Nanshan Commercial Cultural District in Shenzhen, China. The key objective is to better understand the interactions between the socio-economic variables and spatial design parameters of a shopping complex. The research findings point to the importance of multiplicity between syntactic variables and other spatial variables in influencing the pedestrian flows, business performance and tenant mix in highly complex commercial systems. Particularly noteworthy is the relationship between spatial accessibility measures and the location of escalators, and the ways in which individual commercial buildings are embedded into the overall spatial system. The study suggests that this may lead to the preliminary identification of the spatial qualities of effective vertical extensions of mixed land use in a high-density urban settings.

• Journal of Korean Academy of Nursing
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• v.46 no.1
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• pp.149-158
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• 2016

Purpose: This study was done to develop of the Korean intensive care delirium screening tool (KICDST). Methods: The KICDST was developed in 5 steps: Configuration of conceptual frame, development of preliminary tool, pilot study, reliability and validity test, development of final KICDST. Reliability tests were done using degree of agreement between evaluators and internal consistency. For validity tests, CVI (Content Validity Index), ROC (Receiver Operating Characteristics) analysis, known group technique and factor analysis were used. Results: In the reliability test, the degree of agreement between evaluators showed .80~1.00 and the internal consistency was KR-20=.84. The CVI was .83~1.00. In ROC analysis, the AUC (Area Under the ROC Curve) was .98. Assessment score was 4 points. The values for sensitivity, specificity, correct classification rate, positive predictive value, and negative predictive value were found to be 95.0%, 93.7%, 94.4%, 95.0% and 93.7%, respectively. In the known group technique, the average delirium screening tool score of the non-delirium group was $1.25{\pm}0.99$ while that of delirium group was $5.07{\pm}1.89$ (t= - 16.33, p <.001). The factors were classified into 3 factors (cognitive change, symptom fluctuation, psychomotor retardation), which explained 67.4% of total variance. Conclusion: Findings show that the KICDST has high sensitivity and specificity. Therefore, this screening tool is recommended for early identification of delirium in intensive care patients.

• Journal of Information Technology Applications and Management
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• v.20 no.4
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• pp.235-247
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• 2013

The evolution of information technology and proliferation of hospital management and managerial applications of computing has led to change in the characteristics, uses and evaluations of software for the hospital management. With the growing proliferation of microcomputer use and the value-added for management strategies, more and more software has been massively developed, produced and distributed for the hospital industry. The user is faced with an increasingly difficult choice in the evaluation and selection of software. For many reasons, users frequently must rely on expert evaluations of the technical functions and quality of software. The objectives of this study are to provide selection criteria for an Electronic Medical Record (EMR) and to develop an evaluation framework for the Hospital Information Systems. The major findings of our study are as follows (1) the identification of EMR evaluation characteristics (2) the design and development of EMR selection model and (3) the evaluation of the importance for EMR characteristics using Analytic Hierarchy Process (AHP). We identify 6 characteristics and 22 sub-characteristics of the EMR, calculate their weights, and decide the best configuration. Especially, the AHP methodology can be applied to gather knowledge from multiple experts. Because AHP can 1) facilitate the participation of multiple experts 2) increase group productivity and therefore result in both quantitatively and qualitatively superior outcomes than that of a single individual's work 3) provide a mechanism for reconciling conflict from multiple expert 4) validate the acquired knowledge, providing consistency of facts, and 5) enhance the accuracy reliability of the acquired knowledge increase through of the reliability provided by consensus across multiple experts. Although some further research is required, the proposed model can be regarded as a basis for the selection of EMR.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.30 no.1
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• pp.29-37
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• 2020

Work to improve network throughput has been focused on network coding as the utilization of IoT-based application services increases and network usage increases rapidly. In network coding, nodes transform packets received from neighboring nodes into a combination of encoded packets for transmission and decoding at the destination. This scheme is based on trust among nodes, but in the IoT environment where nodes are free to join, a malicious node can fabricate the packet if it legally participates in the configuration. It is difficult to identify the authenticity of the encoded packet since the packet received at destination is not a single source but a combination of packets generated by several nodes. In this paper, we propose a method to detect "look-like-valid" packets that have been attacked and disguised in packets received at destination, and to identify valid messages in the reconstructions. This method shows that network coding performance is significantly improved because the destination can reconstruct a valid message with only received packets without retransmission with a high probability, despite the presence of disguised packets.

• Wind and Structures
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• v.10 no.5
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• pp.463-479
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• 2007

A series of wind tunnel sectional model dynamic tests of a twin-deck bridge were conducted at the CLP Power Wind/Wave Tunnel Facility (WWTF) of The Hong Kong University of Science and Technology (HKUST) to investigate the effects of gap-width on the self-excited vibrations and the dynamic and aerodynamic characteristics of the bridge. Five 2.9 m long models with different gap-widths were fabricated and suspended in the wind tunnel to simulate a two-degrees-of-freedom (2DOF) bridge dynamic system, free to vibrate in both vertical and torsional directions. The mass, vertical frequency, and the torsional-to-vertical frequency ratio of the 2DOF systems were fixed to emphasize the effects of gap-width. A free-vibration test methodology was employed and the Eigensystem Realization Algorithm (ERA) was utilized to extract the eight flutter derivatives and the modal parameters from the coupled free-decay responses. The results of the zero gap-width configuration were in reasonable agreement with the theoretical values for an ideal thin flat plate in smooth flow and the published results of models with similar cross-sections, thus validating the experimental and analytical techniques utilized in this study. The methodology was further verified by the comparison between the measured and predicted free-decay responses. A comparison of results for different gap-widths revealed that variations of the gap-width mainly affect the torsional damping property, and that the configurations with greater gap-widths show a higher torsional damping ratio and hence stronger aerodynamic stability of the bridge.