• Journal of Information Technology Services
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• v.12 no.1
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• pp.83-98
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• 2013

Advanced IT of Korea is the important factor that has improved the performance of business to business e-business systems, especially On-Line E-procurement System (KONEPS). Obviously KONEPS is well positioned in businesses of Korea. In order to be higher performance in KONEPS, it needed to be analysed important characteristics composed of KONEPS. Even though KONEPS has been operating well, user's satisfaction and customer loyalty for KONEPS was not high in real businesses. In this research, we tried to find the factors affecting user satisfaction and customer loyalty for KONEPS and figure out the mechanism among the factors. We surveyed using characteristics, which are information diversity, usability, system reliability and stability, on suppliers, main users of KONEPS. We consider the using characteristics as independent factors of the research model. Meanwhile, we model user's satisfaction and customer loyalty as the dependent factors. The results from the study are helpful in providing policies and strategies to promote the use of KONEPS.

• Asia pacific journal of information systems
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• v.25 no.3
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• pp.500-518
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• 2015

The present research aims to identify the relationship between trust and distrust in an online business environment. To clarify the concepts, cognitive-affective personality system theory was introduced, through which five types of psychological units were proposed. In developing the research model based on the theory, technical effectiveness of the system and content truthfulness of the website were selected as two key stimuli for the coding process of online users. Trust and distrust were selected as mediating factors that generate consequent behaviors. Finally, purchase intention served as a final dependent variable. Assuming that trust and distrust emerge in psychologically different stages, this study hypothesized the mutual causal relationship between trust and distrust, indicating that the relationship will be determined by their contextual emphasis on each dimension. To validate, a survey was conducted with 307 online shopping mall users. Results show that stimuli were more significantly associated with trust. Trust is therefore a more cognitive construct than distrust, and the path from trust to distrust is stronger than that from distrust to trust. This finding implies that the cognitive aspect of trust is stronger than that of distrust. Distrust is rather more affectively emerging than trust.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.10
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• pp.3423-3438
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• 2014

In recent years, wearable sensor devices are reshaping the way people live, work, and play. A wearable sensor device is a computer that is subsumed into the personal space of the user, and is always on, and always accessible. Therefore, among the most salient aspects of a wearable sensor device should be a small form factor, long battery lifetime, and real-time characteristics. Thereby, sophisticated applications of a wearable sensor device use real-time operating systems to guarantee real-time deadlines. The deterministic multi-dimensional task scheduling algorithms are implemented on ARC (Actual Remote Control) with relatively limited hardware resources. ARC is a wearable wristwatch-type remote controller; it can also serve as a universal remote control, for various wearable sensor devices. In the proposed algorithms, there is no limit on the maximum number of task priorities, and the memory requirement can be dramatically reduced. Furthermore, regardless of the number of tasks, the complexity of the time and space of the proposed algorithms is O(1). A valuable contribution of this work is to guarantee real-time deadlines for wearable sensor devices.

• International journal of advanced smart convergence
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• v.9 no.3
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• pp.207-214
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• 2020

Currently, the operation of unmanned aerial vehicle (UAV) is regulated to be able to fly only within the visible range, but in recent years, the needs for operation in the invisible area, in the urban area and at night have increased. In order to operate UAVs in the invisible area, at night, and in the urban area, a flight path for UAVs must be prepared like those operated by manned aircraft, and for this, it is necessary to establish an unmanned aircraft system traffic management (UTM). In order to establish the UTM, information on the minimum separation distance to prevent collisions with UAVs and buildings is required, and accordingly, information on the navigation performance of UAVs is required. In order to analyze the navigation performance of an UAV, total system error (TSE), which is the difference between the planned flight path and the actual location of the UAV, is required. If the collected data are insufficient and classification according to integrity, independence, and direction is not performed, accurate navigation performance is not derived. In this paper, propose a navigation performance analysis method of UAV that is derived TSE using flight data and modeled with normal distribution, analyze performance.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.3
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• pp.1136-1151
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• 2018

This paper proposes a new hybrid scheme to decrease the high peak to average power ratio (PAPR) of optical orthogonal frequency division multiplexing (OFDM) signals in visible light communication (VLC) systems. The PAPR causes nonlinear signal distortions and high power requirements for the VLC transmitter (light emitting diode, LED). The proposed method is applicable for both direct current-biased optical OFDM (DCO-OFDM) and asymmetrically clipped optical OFDM (ACO-OFDM). In the proposed scheme, the PTS method is firstly modified to fit both optical OFDM approaches transmission and then combined with signal clipping method for further PAPR reduction and bit error rate (BER) improvement of the VLC system. The performance of hybrid scheme has been evaluated and compared with the original OFDM based VLC system, conventional PTS and clipping methods. The results show that the hybrid scheme outperforms other methods in terms of both the PAPR reduction and BER performance.

• Journal of the Korean Solar Energy Society
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• v.27 no.2
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• pp.37-44
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• 2007

As photovoltaic(PV) power generation system becomes more common, it will be necessary to investigate islanding detection method for PV systems. Islanding of PV systems can cause a variety of problems and must be prevented. However, if the real and reactive power of the load and PV system are closely matched, islanding detection by Passive methods becomes difficult. Also, most active methods lose effectiveness when there are several PV systems feeding the same island. The active frequency drift positive feedback method(AFDPF) enables islanding detection by forcing the frequency of the voltage in the island to drift up or down. In this paper the research for the minimum value of chopping fraction gain applied digital phase-locked-loop (DPLL) to AFDPF considering output power quality and islanding prevention performance are performed by simulation and experiment according to IEEE Std 929-2000 islanding test.

• Journal of Korea Society of Industrial Information Systems
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• v.10 no.1
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• pp.58-71
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• 2005

Intelligent agents help automate various tasks, including automated negotiations, on-line auction, and buying/selling products over the Internet. To date, most of the agents are developed only for experiments and some of them are implemented on the limited areas such as an auction. The main objective of this paper is to provide a brief overview of negotiation agents. In doing so, previous studies on negotiation agent systems are revisited and then applications in the real world are reviewed. The limitations on the current negotiation agents are defined and future research directions are suggested.

• The Journal of Information Systems
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• v.15 no.1
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• pp.49-71
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• 2006

With a rapid diffusion of internet, more peoples are interested in electronic commerce and the various electronic commerce types are being appeared. In these respects, the internet auction being take the more attentions at the present. Since perceived usefulness and perceived ease of use are such a fundamental driver of usage intentions, it is important to understand the determinants of this construct and how their influences change. In these respects, the web site joyfulness, the web site trust and the institutional mechanism are included as the moderating variables in our research model. A better understanding of the interactions of these factors to the usage intention to the auction site would enable us to design the organizational interventions that would increase the user acceptance and the usage of auction systems. Therefore, the goal of the present research is to extend the organizational model of auction system with TAM's perceived usefulness and perceived ease of use and the additional motivating determinants. The result showed that the web site joyfulness and the trust were the significant determinants on the the usage of auction site. However, the direction of the effect was not consistant through the cases. The model suggested in this study need to be extended with including the more sociological factors and the empirical results founded in this study are required to be verified with the extended model.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.29 no.2
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• pp.75-82
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• 2006

본 연구에서 조합 최적화(Combinatorial Optimization) 이론에 바탕을 두고 있는 네스티드 분할(Nested Partition, 이하 NP) 방법을 이용한 최적화 기탄 요소선택 방법(Feature Selection)을 제안한다. 이 새로운 방법은 좋은 요소 부분집합을 찾는 휴리스틱 탐색 절차를 채용하고 있으며 데이터의 인스턴스(Instances 또는 Records)의 무작위 추출(Random Sampling)을 이용하여 이 요소선택 방법의 처리시간 관점에서의 성능을 항상 시키고자 한다. 이 새로운 접근 방법은 처리시간 향상을 위해 2단계 샘플링 방법을 채용하여 근접 최적해로의 수렴(Convergence)을 보장하는 샘플 사이즈를 결정한다. 이는 앨고리듬이 유한한 시간내에 끝이날 때 최종 요소 부분집합 해의 질(Qualtiy)에 관한 정확한 설명을 할 수 있는 이론적인 배경을 제시한다. 중요 결과를 예시하기 위해서 다양한 형태의 다섯 개의 데이터 셋을 이용하였으며 다섯 번의 반복 실험을 통한 실험 결과가 제시되며, 이 새로운 접근 방법이 기존의 단순 네스티드 분할 방법 기반의 요소선택 방법보다 처리시간 관점에서 더욱 효율적임을 보여준다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.10C
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• pp.921-932
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• 2002

In this research, we seek to identify an effective operation management strategy of telecommunication systems. In order to develop operation management strategies, we implement a quantitative techno-economic analysis. We evaluate related issues and factors, and apply the developed method to PSTN switching systems. In the proposed techno-economic modeling, we apply a well-known factor analysis technique-analytic hierarchy process-to evaluate PSTN operation management strategies. Then, we implement a decision analysis methodology to evaluate the cost of proposed strategies. We evaluate the proposed methodology by using available real data of the PSTN system. The primary impact of this research will be realized in helping PSTN operator select the best operation management strategy of PSTN system.