• Journal of Convergence for Information Technology
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• v.10 no.8
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• pp.203-212
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• 2020

The purpose of this study was to investigate the effects of cognitive rehabilitation programs using Virtual Reality(VR) content on the daily living abilities such as cognitive abilities, depression, and upper extremity functions of the elderly. The study group analyzed the effectiveness by separating the experimental group, which is the virtual reality cognitive rehabilitation application group, and the control group, the universal cognitive stimulation program application group. As a result of the study, the MMSE-K score improved by 13.0% in the experimental group and 2.3% in the control group. The improvement in each area of the experimental group was found to be 3.1% MBI, 7.1% MFT(Rt.), 3.5% MFT(Lt.), and 25.4% K-GDS. As a result of comparing the pre-post score change between each group, there was a significant difference between groups in daily living ability (p<.001) and MFT(Rt.)(p<.01). In addition, as a result of comparing the changes in absolute alpha waves to confirm the degree of depression through brain waves, there was no statistically significant difference. However, in the experimental group, it was confirmed that the average value increased to a positive value. This study is an experiment to verify the effectiveness of the cognitive rehabilitation program using virtual reality contents, and suggests a new intervention method to maintain and improve the daily life ability, cognitive function, depression and upper extremity function of the elderly.

• Journal of the Korea Society of Computer and Information
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• v.19 no.6
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• pp.93-100
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• 2014

The objective of this study is to propose the measurement system implementation method for the evaluation and measurement of the indoor-impulsive over 170 dB noise source. For the purpose of measuring impulse noise, design and implementation constructed followed subsystems of the testing center, microphone, ear simulator, head and torso simulator and so on. Measurement systems for the accuracy and reliability of impulse noise are implemented when measuring 3 ways of measurements method by the simultaneous measurement system design. For the accuracy and reliability of three mutually indoor-impulse noise measurements were compared, three kinds of measuring methods in accordance with the peak sound pressure level and octave band. Comparing the results of data, the indoor-impulse noise by analyzing a frequency characteristic was validated in difference for the statistical significance. Result are determined by the influence of the reflected wave. Therefore, the flexible size of the interior test site while interior impulse noise measurement system was constructed. Throughout this system can be affected by parameters that are the impulse noise source and the corresponding frequency-characteristic analysis to determine the spectrum of the reflected wave. And, in the near future, indoor impulse noise measurement systems for acquisition and analysis are utilized in useful data.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.7 s.349
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• pp.1-13
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• 2006

In this paper, we introduce a novel key management scheme that is based on the key pre-distribution but provides the key re-distribution method, in order to manage keys for message encryption and authentication of lower-layer sensor nodes on hierarchical mobile sensor networks. The characteristics of our key management are as follows: First, the role of key management is distributed to aggregator nodes as well as a sink node, to overcome the weakness of centralized management. Second, a sink node generates keys using regression model, thus it stores only the information for calculating the keys using the key information received from nodes, but does not store the relationship between a node and a key, and the keys themselves. As the disadvantage of existing key pre-distributions, they do not support the key re-distribution after the deployment of nodes, and it is hard to extend the key information in the case that sensor nodes in the network enlarge. Thirdly, our mechanism provides the resilience to node capture(${\lambda}$-security), also provided by the existing key pre-distributions, and fourth offers the key freshness through key re-distribution, key distribution to mobile nodes, and scalability to make up for the weak points in the existing key pre-distributions. Fifth, our mechanism does not fix the relationship between a node and a key, thus supports the anonymity and untraceability of mobile nodes. Lastly, we compare ours with existing mechanisms, and verify our performance through the overhead analysis of communication, computation, and memory.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.48 no.5
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• pp.107-116
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• 2011

In this paper, a traffic adaptive sleep based medium access control (TAS-MAC) protocol for wireless sensor networks (WSNs) is proposed. The protocol aims for WSNs which consist of clustered sensor nodes and is based on TDMA-like schema. It is a typical schedule based mechanism which is adopted in previous protocols such as LEACH and Bit-Map Assisted MAC. The proposed MAC, however, considers unexpected long silent period in which sensor nodes have no data input and events do not happen in monitoring environment. With the simple traffic measurement, the TAS-MAC eliminates scheduling phases consuming energy in previous centralized approaches. A frame structure of the protocol includes three periods, investigation (I), transmission (T), and sleep-period (S). Through the I-period, TAS-MAC aggregates current traffic information from each end node and dynamically decide the length of sleep period to avoid energy waste in long silent period. In spite of the energy efficiency of this approach, the delay of data might increase. Thus, we propose an advanced version of TAS-MAC as well, each node in cluster sends one or more data packets to cluster head during the T-period of a frame. Through simulation, the performance in terms of energy consumption and transmission delay is evaluated. By comparing to BMA-MAC, the results indicate the proposed protocol is more energy efficient with tolerable expense in latency, especially in variable traffic situation.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.5
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• pp.1-6
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• 2007

In wireless mesh networks (WMNs), the end-to-end throughput of a flow decreases drastically according to the traversed number of hops due to interference among different hops of the same flow in addition to interference between hops of different flows with different paths. This paper proposes a distributed multi-channel assignment scheme based on hops (DMASH) to improve the performance of a static WMN. The proposed DMASH is a novel distributed multi-channel assignment scheme based on hops to enhance the end-to-end throughput by reducing interference between channels when transmitting packets in the IEEE 802.11 based multi-interface environments. The DMASH assigns a channel group to each hop, which has no interference between adjacent hops from a gateway in channel assignment phase, then each node selects its channel randomly among the channel group. Since the DMASH is a distributed scheme with unmanaged and auto-configuration of channel assignment, it has a less overhead and implementation complexity in algorithm than centralized multi-channel assignment schemes. Simulation results using the NS-2 showed that the DMASH could improve remarkably the total network throughput in multi-hop environments, comparing with a random channel assignment scheme.

• Journal of Korean Association for Spatial Structures
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• v.8 no.3
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• pp.65-73
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• 2008

The present work deals with subjective assessments to propose the objective parameter related to the subjective attribute of reverberation in the coupled room varied the aperture opening size. A 1/10 scale model was built and used for the measurements and subjective assessments. For the subjective tests, binaural impulse responses(BIRs) were measured using a dummy head and the measured BIRs were convolved with anechoic recorded music for the presentation over the headphones. The results showed that the perceived reverberation was the largest in the aperture opening size 12.5%(1.97% of mail) room surface area)and decreased with increasing the aperture opening size over 25% (3.94% of main room surface area) in the main room coupled with the secondary reverberant room. In the main room coupled with the secondary absorptive room, there was no changes in the perceived reverberation up to the aperture opening size 6.25%(0.99% of main room surface area) and it gradually decreased with increasing the aperture opening site over 12.5%. The objective parameter, T30/T15, showed a very low correlation with the perceived reverberation in the coupled room varied the aperture opening size but showed a high correlation with a new objective parameter, T30/Tbp, proposed by the authors. Because the late part decay energy more rapidly increases with increasing the aperture opening site than the early and middle part decay energy, the LDT/EDT or T3/T1 is a better quantifier to measure double slopes in the coupled room than the T30/T15.

• Journal of the Korean Magnetics Society
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• v.9 no.2
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• pp.111-120
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• 1999

The effects of annealing in rotating magnetic field after deposition on electromagnetic properties of $Co_{82}Zr_6Mo_{12}$ thin (200~1200 $\AA$) films prepared by RF-magnetron sputtering were investigated in terms of microstructure and surface morphology. The coercivity decreases, but $4{\pi}M_5$ does not change with increasing the film thickness. The coercivity of the films was decreased below 300 $^{\circ}C$ due to stress relief and decreasing the surface roughness, while increased at 400 $^{\circ}C$ due to partial grain growth. And then, $4{\rho}M_5$ was almost independent of annealing temperatures below 200 $^{\circ}C$, but increased from 7.4 kG to 8.0 kG at 300 $^{\circ}C$ and at 400 $^{\circ}C$, which was caused by precipitation and growth of fine Co particles in the films. The electrical resistivity of films was decreased with increasing annealing temperatures and the magnetoresistance was a negative value of nearly 0 $\mu$$\Omega$cm. After annealing at 300 $^{\circ}C$, maximum effective permeability was 1200 to the hard axis of the thin films according to high frequency change. Considering the practical application of biasing layers of the films for magnetoresistive heads, optimal annealing conditions was obtained after one hour annealing at 300 $^{\circ}C$ in 400 Oe rotating magnetic field.

• Food Science and Preservation
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• v.17 no.6
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• pp.908-913
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• 2010

Modified atmosphere packaging (MAP) was evaluated for the storage of pumpkin rice cake as a means of preserving quality and extending shelf-life. Retail-sized amounts of rice cake were packaged in trays under different modified atmosphere conditions (air, vacuum, 60% $CO_2$/40% $N_2$ and 100% $CO_2$) using gas-barrier plastic film; control was in air-permeable stretch wrap. The packages were stored at $20^{\circ}C$ with periodical measurement of package atmosphere and cake quality attributes. The modified atmosphere packages of 60% $CO_2$/40% $N_2$ and 100% $CO_2$ inhibited the growth of molds/yeasts completely and significantly retarded the growth of aerobic bacteria. All the packages except that of 100% $CO_2$ showed the reduction of internal $O_2$ concentration and increase of the $CO_2$ with storage time due to the microbial activity. There has been slight decrease of $CO_2$ concentration for 60% $CO_2$/40% $N_2$ and 100% $CO_2$ packages just after start of the storage possibly due to dissolution of headspace $CO_2$ into the cake. Any MAP conditions did not affect the retrogradation of the rice cake. Surface color of the cake within affordable microbial quality limit was not affected significantly by packaging conditions.

• Journal of KIISE:Software and Applications
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• v.27 no.2
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• pp.193-200
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• 2000

The extraction of face regions is required for Head Gesture Interface which is a natural user interface. Recently, many researchers are interested in using color information to detect face regions in image sequences. Two most widely used color models, HSI color model and YIQ color model, were selected for this study. Actually H-component of HSI and I-component of YIQ are used in this research. Given the difference in the color component, this study was aimed to compare the performance of face region detection between the two models. First, we search the optimum range of facial color for each color component, examining the detection accuracy of facial color regions for variant threshold range about facial color. And then, we compare the accuracy of the face box for both color models by using optimal facial color and motion information. As a result, a range of $0^{\circ}{\sim}14^{\circ}$ in the H-component and a range of $-22^{\circ}{\sim}-2^{\circ}$ in the I-component appeared to be the most optimum range for extracting face regions. When the optimal facial color range is used, I-component is better than H-component by about 10% in accuracy to extract face regions. While optimal facial color and motion information are both used, I-component is also better by about 3% in accuracy to extract face regions.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.4B
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• pp.323-338
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• 2003

The main memory database systems (MMDBMS) efficiently supports various database applications that require high performance since it employs main memory rather than disk as a primary storage. Recently, it has been increased needs that have the fast data processing as well as the efficient modeling of application requiring for a complicated structure, and conformity to applications that need the strict dta consistency. In MMDBMS, because all the data is located in the main memory, it can support the usable expression methods of data satisfying their needs without performance overhead. The method has the operation to manipulate the data and the constraint such as referential integrity in more detail. The data model consists of this methods is an essential component to decide the expression power of DBMS. In this paper, we discuss about various requests to provide the communication services and propose the data model that support it. The mainly discussed issues are 1) definition of the relationship between tables using the pointer, 2) navigation of the data using the relationship, 3) support of the referential integrity for pointer, 4) support of the uniform processing time for the join, 5) support of the object-oriented concepts, and 6) sharing of an index on multi-tables. We discuss the pointer-based data model that designed to include these issues to efficiently support complication environments.