• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.11A
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• pp.1087-1094
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• 2008

In this paper, we propose the acquisition method of the Cyclic-Prefix CDMA using Good-Autocorrelation-Sequence (GAS-CP-CDMA) system. The sequences for GAS-CP-CDMA are m-sequence and constant amplitude zero autocorrelation code (CAZAC) with good autocorrelation property. The GAS-CP-CDMA system is proposed for interference cancellation in multi-user and -path environment in co-cell. However, the reliable initial acquisition in multi-path fading channel and multi-user system environment is crucial. In this paper, non-coherent power detector and threshold value are used for discriminating signal acquisition. The sequence used for computer simulation is CAZAC. The simulation results show proper threshold value depends on the number of users. Through the computer simulation, we draw setting up method of the optimum threshold value for the GAS-CP-CDMA system.

• Journal of Intelligence and Information Systems
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• v.19 no.2
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• pp.39-54
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• 2013

Recent explosive increase of electronic commerce provides many advantageous purchase opportunities to customers. In this situation, customers who do not have enough knowledge about their purchases, may accept product recommendations. Product recommender systems automatically reflect user's preference and provide recommendation list to the users. Thus, product recommender system in online shopping store has been known as one of the most popular tools for one-to-one marketing. However, recommender systems which do not properly reflect user's preference cause user's disappointment and waste of time. In this study, we propose a novel recommender system which uses data mining and multi-model ensemble techniques to enhance the recommendation performance through reflecting the precise user's preference. The research data is collected from the real-world online shopping store, which deals products from famous art galleries and museums in Korea. The data initially contain 5759 transaction data, but finally remain 3167 transaction data after deletion of null data. In this study, we transform the categorical variables into dummy variables and exclude outlier data. The proposed model consists of two steps. The first step predicts customers who have high likelihood to purchase products in the online shopping store. In this step, we first use logistic regression, decision trees, and artificial neural networks to predict customers who have high likelihood to purchase products in each product group. We perform above data mining techniques using SAS E-Miner software. In this study, we partition datasets into two sets as modeling and validation sets for the logistic regression and decision trees. We also partition datasets into three sets as training, test, and validation sets for the artificial neural network model. The validation dataset is equal for the all experiments. Then we composite the results of each predictor using the multi-model ensemble techniques such as bagging and bumping. Bagging is the abbreviation of "Bootstrap Aggregation" and it composite outputs from several machine learning techniques for raising the performance and stability of prediction or classification. This technique is special form of the averaging method. Bumping is the abbreviation of "Bootstrap Umbrella of Model Parameter," and it only considers the model which has the lowest error value. The results show that bumping outperforms bagging and the other predictors except for "Poster" product group. For the "Poster" product group, artificial neural network model performs better than the other models. In the second step, we use the market basket analysis to extract association rules for co-purchased products. We can extract thirty one association rules according to values of Lift, Support, and Confidence measure. We set the minimum transaction frequency to support associations as 5%, maximum number of items in an association as 4, and minimum confidence for rule generation as 10%. This study also excludes the extracted association rules below 1 of lift value. We finally get fifteen association rules by excluding duplicate rules. Among the fifteen association rules, eleven rules contain association between products in "Office Supplies" product group, one rules include the association between "Office Supplies" and "Fashion" product groups, and other three rules contain association between "Office Supplies" and "Home Decoration" product groups. Finally, the proposed product recommender systems provides list of recommendations to the proper customers. We test the usability of the proposed system by using prototype and real-world transaction and profile data. For this end, we construct the prototype system by using the ASP, Java Script and Microsoft Access. In addition, we survey about user satisfaction for the recommended product list from the proposed system and the randomly selected product lists. The participants for the survey are 173 persons who use MSN Messenger, Daum Caf$\acute{e}$, and P2P services. We evaluate the user satisfaction using five-scale Likert measure. This study also performs "Paired Sample T-test" for the results of the survey. The results show that the proposed model outperforms the random selection model with 1% statistical significance level. It means that the users satisfied the recommended product list significantly. The results also show that the proposed system may be useful in real-world online shopping store.

• IE interfaces
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• v.10 no.1
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• pp.135-143
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• 1997

The importance of training for NC, CNC and Machining Center has been greatly increased. This paper presents implementation of a DNC(Direct Numerical Control) operating software for educational system. This system is able to connect 8-32 CNCs to Control PC with RS232 multi-port serial card. Therefore, it allows much efficiency in training even after costs are considered. The KISCO DNC S/W for above system includes various communication functions, communication parameters setting, program editor and user-friendly environment. This software was developed with C and Windows programming. It was proved in function and stability by iterative field tests.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.53 no.3
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• pp.129-133
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• 2004

As In DS/CDMA(direct sequence code division multiple access) system, the system capacity is limited by multiple access interference(MAI), and self-interference(SI) resulting from the multi-path propagation of the desired user signal. This paper, which the approximated analytic chip waveforms are nearly the same as the computer generated chip waveforms are shown. And then, the BER(Bit Error Rate) performances in CDMA system using the approximated analytic chip waveforms are shown.

• 한국HCI학회:학술대회논문집
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• 2009.02a
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• pp.961-970
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• 2009

Over the last decade, interactive devices such as mobile phones have become complicated drastically mainly because of feature creep, the tendency for the number of features in a product to rise with each release of the product. One of the ways to reduce the complexity of a multi-functional device is to design it consistently. Although the definition of consistency is elusive and it is sometimes beneficial to be inconsistent, in general, consistently designed systems are easier to learn, easier to remember, and causing less errors. In practice, however, it is often not easy to design the user interaction or interface of a multi-functional device consistently. Since the interaction design of a multi-functional device should deal with a large number of design variables and relations among them, solving this problem might be very time-consuming and error-prone. Therefore, there is a strong need for a well-developed methodology that supports the complex design process. This study has developed an effective and efficient methodology, called CUID (Consistent Design of User Interaction), which focuses on logical consistency rather than physical or visual consistency. CUID deals with three main problems in interaction design: procedure design for each task, decisions of available operations(or functions) for each system state, and the mapping of available operations(functions) and interface controls. It includes a process for interaction design and a software tool for supporting the process. This paper also demonstrates how CUID supports the consistent design of user interaction by presenting a case study. It shows that the logical inconsistencies of a multi-functional device can be resolved by using the CUID methodology.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.2
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• pp.40-46
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• 2010

Multi-user MIMO (Multiple-Input Multiple-Output) systems require collaborative PF schedulers to improve the performance of the log sum of average transmission rates. While the performance of single cell based conventional PF schedulers has been evaluated over various channel conditions, scheduling algorithms by multiple base stations which select multiple users over a given time frame and their performance require further investigations. In this paper, we apply a collaborative PF scheduler to the distributed multi-user MIMO system, which assigns radio resources to multiple users by exchanging user channel information from base stations located in three adjacent sectors. We further evaluate its performance in terms of the log sum of average transmission rates. The performance is compared to that of the full-search collaborative PF scheduler which searches over all possible combinations of user groups, and that of a parallel PF scheduler that determines users without channel information exchange among base stations. We show the log sum of average transmission rates of the collaborative PF scheduler outperforms that of the parallel PF scheduler in low percentile region. In addition, the collaborative PF scheduler exhibits a negligible performance degradation when compared to the full-search collaborative PF scheduler while a significant reduction of the computational complexity is achievable at the same time.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.3A
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• pp.238-244
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• 2010

We propose a user selection method in multi-cell multiuser uplink system with the subspace interference alignment to maintain the high sum-rate capacity. The proposed method selects users whose interference to adjacent cells are strong and apply the subspace interference alignment to the users. The proposed method provides that the number of users performing the interference alignment reduces and the high total sum-rate is maintained. Simulation results exhibit the proposed method reduces the number of users who would decompose the channel for the subspace interference alignment by 50% when the required sum-rate is 90% of the maximal achievable sum-rate.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1997.10a
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• pp.237-240
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• 1997

This paper is to arrange systematically the geometrical & physical data for real ships and to develop the graphic user interface program for initial hull design using NFHFD, which save the distributed information about hull form database and can output multi-variables.

• IEIE Transactions on Smart Processing and Computing
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• v.5 no.1
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• pp.55-62
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• 2016

In this paper, we propose a hybrid multi.system-on-chip (H-MSoC) architecture that provides a high-flexibility system in a rapid development time. The H-MSoC approach provides a flexible system-on-chip (SoC) architecture that is easy to configure for physical- and application-layer development. The physical- and application-layer aspects are dynamically designed and modified; hence, it is important to consider a design methodology that supports rapid SoC development. Physical layer development refers to intellectual property cores or other modular hardware (HW) development, while application layer development refers to user interface or application software (SW) development. H-MSoC is built from multi-SoC architectures in which each SoC is localized and specified based on its development focus, either physical or application (hybrid). Physical HW development SoC is referred to as physical-SoC (Phy-SoC) and application SW development SoC is referred to as application-SoC (App-SoC). Phy-SoC and App-SoC are connected to each other via Ethernet. Ethernet was chosen because of its flexibility, high speed, and easy configuration. For prototyping, we used a LEON3 SoC as the Phy-SoC and a ZYNQ-7000 SoC as the App-SoC. The proposed design was proven in real-time tests and achieved good performance.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.17 no.3
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• pp.794-815
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• 2023

The rapid development of mobile communication not only has made the industry gradually diversified, but also has enhanced the service quality requirements of users. In this regard, it is imperative to consider jointly network slicing and mobile edge computing. The former mainly ensures the requirements of varied vertical services preferably, and the latter solves the conflict between the user's own energy and harsh latency. At present, the integration of the two faces many challenges and need to carry out at different levels. The main target of the paper is to minimize the energy consumption of the system, and introduce a multi-slice joint task offloading and resource allocation scheme for massive multiple input multiple output enabled heterogeneous networks. The problem is formulated by collaborative optimizing offloading ratios, user association, transmission power and resource slicing, while being limited by the dissimilar latency and rate of multi-slice. To solve it, assign the optimal problem to two sub-problems of offloading decision and resource allocation, then solve them separately by exploiting the alternative optimization technique and Karush-Kuhn-Tucker conditions. Finally, a novel slices task offloading and resource allocation algorithm is proposed to get the offloading and resource allocation strategies. Numerous simulation results manifest that the proposed scheme has certain feasibility and effectiveness, and its performance is better than the other baseline scheme.