• Membrane Journal
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• v.20 no.1
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• pp.29-39
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• 2010

This study focuses on the modeling of DMFC to predict the characteristics and to improve its performance. This modeling requires deep understanding of the design and operating parameters that influence on the cell potential. Furthermore, the knowledge with reference to electrochemistry, transport phenomena and fluid dynamics should be employed for the duration of mathematical description of the given process. Considering the fact that MEA is the nucleus of DMFC, special attention was made to the development of mathematical model of MEA. Multiscale modeling is comprised of process modeling as well as a computational fluid dynamics (CFD) modeling. The CFD packages and process simulation tools are used in simulating the steady-state process. The process simulation tool calculates theelectrochemical kinetics as well as the change of fractions, and at the same time, CFD calculates various balance equations. The integrated simulation with multiscal modeling explains experimental observations of transparent DMFC.

• Asia pacific journal of information systems
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• v.17 no.4
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• pp.1-29
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• 2007

The brand-based online community recently plays an important roles for consumers to facilitates searching and sharing information among them. Firms often find such a brand community as a critical channel to gain collective intelligence for developing new ideas and products. As a new web platform such as web 2.0 has been introduced, consumers could more easily participate in the new social networks created by sharing mutual value and belief among themselves. Accordingly firms began to recognize potentials of online brand assets and pay attention to the importance of online brand community loyalty. Previous research related to online community tends to focus on identifying the antecedents of community loyalty and their subsequent impacts on brand. They, however, tend to neglect the importance of individual characteristics of online community users. As integrating the fragmented variables with an individual characteristics, therefore, this study reexamined the impacts of interactivity, information, reward, and personalization services provided by an online brand community on the sense of community, community loyalty, and brand attitude. Also, this study investigated how users' individual characteristics(need for cognition: NFC) can play moderating roles among the variables identified in the previous research. A field survey was administrated and 671 valid samples were collected. In order to test the hypothesis we conducted the multi-sample structural equation modeling(MSEM) between two groups(a group with high vs. a group with low level of NFC). Results show that previously identified variables such as interactivity, information, reward, and personalization services have significant effects on the sense of community as previous research demonstrated. Subsequently, the sense of community positively influences the community loyalty and brand attitude. However, when considering the NFC as a moderating variable, we found that the effect of interactivity and reward service on the sense of community was stronger for a group with a lower level of NFC compared to a group with a higher level, while the effect of information providing service on the sense of community was stronger for a group with a higher level of NFC compared to a group with a lower level. This research revealed that NFC can affect the degree of individual perception on the sense of community which has been considered as an important indicator for the community loyalty and brand attitude. Hence, when firms developing customer relation strategy through building an online brand community, they need to reflect customers' NFC and accordingly provide varying degree of interactivity, information, reward, and personalization services.

• Journal of Broadcast Engineering
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• v.12 no.2
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• pp.148-158
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• 2007

Recently, IEEE 802.15.4a(low-rate UWB) technique has been paid much attention to the LR-UWB communication system for WPAN. However, there are various interferences such as MPI(Multi Path Interference) or IPI(Inter Piconet Interference) in IEEE 802.15.4a wireless channel. In order to cancel various interferences occurred to WPAN environment, in this paper, we propose a UWB wireless communication system with high QoS(Quality of Service) which is a chaotic-OOK(On-Off Keying) system using unipolar ZCD(Zero Correlation Duration) spreading code in physical layer level. Furthermore, we analyze its performance via simulations and verify the availability of proposed system with prototype implementation.

• Journal of Korea Society of Industrial Information Systems
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• v.19 no.1
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• pp.13-18
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• 2014

Sensor nodes are used for monitoring and collecting the environmental data via wireless sensor network. The wireless sensor network with various sensor nodes draws attention as a key technology in ubiquitous computing. Sensor nodes has very small memory capacity and limited power resource. Thus, it is essential to have energy efficient strategy for the sensor nodes. Since the sensor nodes are operating on the same frequency bands with ISM frequency bands, the interference by the devices operating on the ISM band degrades the quality of communication integrity. In this paper, the convolutional code is proposed instead of ARQ for the error control for the sensor network. The proposed convolutional code was implemented and the BER performance is measured. For the fixed transmitting powers of -19.2 dBm and -25dBm, the BER with various communication distances are measured. The packet loss rate and the retransmission rate are calculated from the measured BER. It is shown that the porposed method obtained about 9~12% and 12-19% reduction in retransmission rate for -19.2 dBm and -25 dBm respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.8
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• pp.285-293
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• 2017

The purpose of this study is to examine the relationship between the Minnesota Multiphasic Personality Inventory(MMPI-2) clinical scales and the self-regulation quotient of the brain quotient. The test in this study was performed by 41 adults over 20 years old and was done using the MMPI-2, which is a self-reporting method. EEG was performed using a 2-channel EEG System at Fp1 and Fp2. The analysis showed a negative correlation between scale 2(D), which is the MMPI-2 clinical scale, and the SRQ(Self Regulation Quotient) relaxation status, which is the related alpha rhythm. Scale3(Hy) showed a positive correlation with the SRQ concentration status and low ${\beta}$ rhythm. Scale7 in the MMPI-2 clinical scales showed a negative correlation with the SRQ relaxation status, which is the alpha rhythm. This means that MMPI-2 and SRQ can be used complementarily in the field of counseling. These results could be interpreted in three ways. First, people with depression are sensitive to other people's attention and evaluation. Therefore, they tend to expend a lot of energy when forming interpersonal relationships, and if they do not learn to relax, their fatigue can easily be increased. Second, people who seek other people's interest and have a cheerful spirit are considered to be highly active. Third, highly stressed people with anxiety and tension seem to easily become tired and their irritation and discomfort may be increased in consequence.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.5
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• pp.608-616
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• 2017

The purpose of this study was to compare how three kinds of emotionally different music impacted on the emotion and arousal by measuring EEG. The research method was to compare the measurement of the background EEG on Fp1 and Fp2 before, while and after listening using a 2-channel EEG device with various experimental groups aging from 20s to 50s. The results were as follows. 1) At both Fp1 and Fp2, the amplitude of alpha(8-13Hz), SMR(12-15Hz), low beta, high beta, and ${\alpha}/-{\beta}$significantly increased in all music, while at Fp2 only, theta and ??/SMR increased meaningfully.2) At right prefrontal cortex(Fp2), all bands of EEG predominated while and after listening to all songs over Fp1 except for the delta of funeral march which predominated while listening to Fp1.3) The music with a noticeably high alpha value and increased activity was Prelude. These results suggested that Prelude induced brain activity along with relaxation, and the emotionally heavy burden of funeral march decreased the activity of the left brain. This research revealed that feeling emotional change by listening to music was due to the fact that music influenced the brain activity inducing the change of emotion and arousal.

• Korean journal of communication and information
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• v.77
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• pp.36-72
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• 2016

Comprehensive Cable TV Channels(CCCs) has been established as a political product around 5 years ago, and it's influence and position on the broadcasting field are keep increasing. CCC's stabilization is based on flooding the market with journalism. The repeating news and current affairs programs are appearing constantly in the afternoon which is CCC's primetime. The current affairs talk shows are a product of CCC's representative program type and it leads unique CCC style journalism. The guests of the current affairs talk show leading the program with critiques(comments) and discussions about political issues. The purpose of this study is to explore how these guests of the current affairs talk shows conceptually positioned as political mediating elites and same time to explore the television political landscape through the representative current affairs talk shows from TV chosun, Channel A, MBN, JTBC which are present by these political elites. This study wants to find out about that television political effects from CCCs which exemplified into certain directions by these political mediating elites saying their political biases and expresses their feelings drastically that causes high ratings and brings people's attention. The guests who called political mediating elites in this study are mostly considered to be extreme rightist, conservatives, conservative-centrist and they have close relationship with certain political party or political group. The political mediating elites gain the popularities and have great influence on the public from performing the television politics through CCCs' current affairs talk shows and use that to make political exchange connections with political groups. Therefore this study wants to point out that CCCs' current affairs talk shows are situated in political rally, exchange connection, so current affairs talk shows are existing only for political battle field.

• Asia pacific journal of information systems
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• v.22 no.4
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• pp.51-73
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• 2012

Social network services based on openness, connectedness, and mass participation are reshaping many aspects of how companies conduct business and create value for their customers. For instance, Facebook and Twitter are expected to play a pivotal role as a new communication channel through which companies-forge close relationships with their customers for co-creation of value for mutual benefits. Given the potential of social network services, it is not surprising that many companies have strategically invested in social network services to reach out to customers. Despite the growing interest in social network services as a platform to connect companies and their customers, few guidelines exist about how managers can effectively utilize social network services in forging relationships with their customers. As such, scholars should pay greater attention to how firms can successfully develop relationships with their customers on social network services. In particular, this study employs the S-O-R (stimulus-organism-response) framework as a theoretical lens to develop a research model that explains customers' participation in the value co-creation platform that companies opened on Twitter. According to the S-O-R framework, certain types of individuals' behaviors can be best understood based on a causal link from environmental stimulus to organism, and response. We apply the S-O-R framework to understand how ubiquitous connectivity (stimuli) can influence customers' experience (organism) with companies on Twitter, which in turn influence their participation behavior (response). Two steps have been undertaken to empirically test the research model. First, we conducted a content analysis of tweets written by customers who follow companies on Twitter. As a result, we found event/promotion participation, company support, and giving feedback as three specific types of customer participation behavior. Second, we conducted a web-based survey to test research hypotheses in the research model. Participations in the survey were solicited to customers who followed companies on Twitter. As a result, a total of 115 respondents have completed the survey. Data were analyzed using the partial least square (PLS) technique. The results of data analysis suggest that ubiquitous connectivity (stimuli) had strong positive effects on perceive usefulness, perceived enjoyment, and perceived intimacy (organism). Perceived intimacy showed positive effects on customer participation behavior (response), such as event participation, company support, and giving feedback. Perceived enjoyment was found to have strong positive effects on company support and giving feedback. On the other hand, perceived usefulness did not have significant impacts on the three types of customer participation behavior.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.9
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• pp.1248-1256
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• 1993

The propagation and delay properties in opical fiber are particularly attractive because digital signal processing and conventional analog signal processing techniques such as those using surface acoustic wave devices are limited In their usefulness for signal bandwidth exceeding one or two GHz, although they are very effective at lower frequencies. Since an accurate, low loss and short time delay elements can be obtained by using such an optical fiber, optical signal precessing has attracted much attention for high speed and broad-band signal precessing in particular channel separation filtering for optical FDM signals. In this paper, we consider a coherent optical lattice filter, which uses coherent light sources and consists of directional couplers and optical fiber delay elemnts. The optical fiber fitters are more restricted than the usual digital filters. The reasons are as follows. 1) the coupling coefficients of directional couplers are restricted to the number between 0 and 1. 2) optical signal E(complex amplitude) is divided into J If-$\boxUl$ and J L/7$\div$$\boxUl$ at the directional coupler. Considering these restrictions and in this case all the coupling coefficients of summing and branching elements are set to be equal, we have given design formulae for optical lattice filter, which make the best use of optical signal energy.

• Science of Emotion and Sensibility
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• v.19 no.4
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• pp.119-126
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• 2016

In this study, we investigated the effects of mouth breathing on brain activity through electroencephalogram (EEG). EEG was performed on 12 healthy volunteers of age ranging from 21 to 27 years (male: female = 6:6, non-smoker). Brain waves on resting state (Rest_N/Rest_M) and auditory-language stimuli state (Eng_N/Eng_M) were recorded during mouth and nose breathing. Four different regions (R1~R4) were classified based on the brain functionality. And each channel (e.g., Pf1 and Pf2) and frequency (${\alpha}$, ${\beta}$, ${\gamma}$, and ${\theta}$) were analyzed using their absolute power ratios of fast Fourier transform (FFT). The results showed that there was no significant difference between Rest_N and Rest_M. Eng_N had significantly higher brain activity than Rest_N; on the other hand, there was no significant difference between Rest_M and Eng_M. These results demonstrate that mouth-breathing on resting state does not induce any significant effects on brain activity and/or functionality, even though it causes subtle temporary inconvenience. In addition to the uncomfort, the brain activity can be adversely influenced by mouth-breathing, which could lower the cognitive skills under certain circumstances.