• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.7
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• pp.685-691
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• 2004

In this paper, we propose the hybrid methods of SLM(selected mapping) and predistortion, and PTS(partial transmit sequence) and predistortion to reduce PAPR(peak to average power ratio) and to decrease the nonlinear distortion of the nonlinear HPA(high power amplifier) in the multi-code CDMA(code division multiple access) system. The phase rotation factors are transmitted as side information in PTS and SLM methods play an important role in the BER performance. So, we present the theoretical BER equation when the errors of side information are considered in the multi-code CDMA communication system. Simulation results show that PAPR is reduced and nonlinear distortion is compensated by hybrid methods. Therefore BER performance is enhanced.

• Proceedings of the Korean Information Science Society Conference
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• 2011.06a
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• pp.112-115
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• 2011

Healthcare is one of the biggest industries that consume IT Infrastructure as a necessity. A reliable reach to secure private information is the essential goal. Most of the healthcare organizations either have their own custom solutions developed or third part CRM software tailored to their needs. This culture satisfies the usability internal to the organization but lacks the ability to provide public access to the users or even to take a step ahead and collaborate with like minded institutes for research and potential growth. Emergence of cloud computing has provided us the opportunity to take a step ahead and build applications available to users on a secure platform, with ability to scale the resources depending on the requirements. The effective use of hybrid and community cloud can create rock solid foundations for healthcare IT Infrastructure. These cloud deployment models not only caters the present needs of healthcare IT Infrastructure but also opens the possibilities to build applications and provide secure and reliable access beyond the limits of organizational boundaries.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.3C
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• pp.228-236
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• 2006

A Multicarrier code division multiple access(MC-CDMA) is a scheme that combines multicarrier modulation with CDMA. It offers robustness to frequency selective fading effect and can support higher rate data transmission with higher spectral efficiency. The objective of this article is proposed and analyzed a new asynchronous MC-CDMA system with various kinds of data rates which employs a multiple access interference (MAI) canceller. The proposed multirate MC-CDMA system can be accomplished by changing the number of Parallel branch(P) according to their data rate and hybrid interference canceller(HIC) are used for MAI cancellation. We compare the performance of proposed system in terms of average bit error rate(BER) with that of a single rate MC-CDMA system. The results show the large improvement in performance that can be attained by the cancellation scheme under multipath environments.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.9
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• pp.2081-2100
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• 2013

In this paper, we propose a cooperative hybrid spectrum sharing protocol by jointly considering interweave (opportunistic) and underlay schemes. In the proposed protocol, secondary users can access the licensed spectrum along with the primary system. Our network scenario comprises a single primary transmitter-receiver (PTx-PRx) pair and a group of M secondary transmitter-receiver (STx-SRx) pairs within the transmission range of the primary system. Secondary transmitters are divided into two groups: active and inactive. A secondary transmitter that gets an opportunity to access the secondary spectrum is called "active". One of the idle or inactive secondary transmitters that achieves the primary request target rate $R_{PT}$ will be selected as a best decode-and-forward (DF) relay (Re) to forward the primary information when the data rate of the direct link between PTx and PRx falls below $R_{PT}$. We investigate the ergodic capacity and outage probability of the primary system with cooperative relaying and outage probability of the secondary system. Our theoretical and simulation results show that both the primary and secondary systems are able to achieve performance improvement in terms of outage probability. It is also shown that ergodic capacity and outage probability improve when the active secondary transmitter is located farther away from the PRx.

• 한국정보통신설비학회:학술대회논문집
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• 2008.08a
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• pp.237-241
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• 2008

Femtocells are cellular access points that connect to a mobile operator's network using residential DSL or cable broadband connections. They have been developed to work with a range of different cellular standards including CDMA, GSM and UMTS. Like legacy base station, the frequency accuracy and phase alignment is necessary for ensuring the quality of service (QoS) for applications such as voice, real-time video, wireless hand-off, and data over a converged access medium at the femtocell. But, the GPS has some problem to be used at the femtocell, because it is difficult to set-up, depends on the satellite condition, and very expensive. So, some techniques are discussed to alternate with the legacy GPS system. NTP, PTP, Synchronous Ethernet use the ethernet to synchronize distributed clocks in packet networks. AGPS support reliable position information than the legacy GPS in poor signal conditions. But, These method also have some problems. So, hybrid timing method like A-GPS+PTP and TV+GPS was developed to make up the weak point of GPS. This paper introduces the each method and compare each other and y propose much better solution for timing synchronization at the Femtocell

• The Journal of Korean Association of Computer Education
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• v.18 no.6
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• pp.43-51
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• 2015

In this paper, we develops the hybrid career coaching model combined the face to face and the E-coaching, and applies students of childhood education for career guidance. The presented hybrid career coaching manages a profile and state information and a remote access between the coach and coachee on Internet. Then, online part of hybrid coaching deals with saving the data, and understand of the situation of the coachee if it is necessary. And face to face part of hybrid coaching have a conversation, the checking, counsel and introspection if the coach needs. Presented hybrid career coaching model has th procedure of 6 steps such like career coaching guidance, self-understanding, career decision-making, establishment of the career execution planning, execution plan and action will inspection and execution result inspection. Proposed hybrid career coaching is possible to understand coachee's current state on the career map, realize the importance of the execution strategy and maximize the efficiency and effectiveness self-regulation capacity.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.20 no.1
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• pp.149-153
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• 2020

This paper presents a new page placement policy for DRAM/NVRAM hybrid main memory in smartphones. Unlike previous studies on hybrid memory systems, this paper performs the placement of pages based on the offline analysis of memory access behaviors as smartphone's memory accesses are skewed to a certain address ranges, which is consistent regardless of smartphone applications, specially for write operations. Thus, we aim at reducing the write traffic to NVRAM by the offline analysis results. Experimental results show that the proposed policy reduces the write traffic to NVRAM by 61% on average without performance degradations.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.37 no.11
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• pp.17-22
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• 2000

A novel and robust direct parameter extraction method for hybrid-p equivalent circuit model of HBT is proposed. A new expression that can accurately resolve the base internal resistance from the measured S-parameters is derived, and it is not sensitive to the values of parasitic access inductance values. Based on the expression, six analytical expressions for the other parameters is developed and these expressions for hybrid-p equivalent circuit modeling ensure robust, fast, and reliable parameter extraction.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.6
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• pp.2078-2094
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• 2015

Now a days, Efficient processing of Broadcast Queries is of critical importance with the ever-increasing deployment and use of mobile technologies. BQs have certain unique characteristics that the traditional spatial query processing in centralized databases does not address. In novel query processing technique, by maintaining high scalability and accuracy, latency is reduced considerably in answering BQs. Novel approach is based on peer-to-peer sharing, which enables us to process queries without delay at a mobile host by using query results cached in its neighboring mobile peers. We design and evaluate cooperative caching techniques to efficiently support data access in ad hoc networks. We first propose two schemes: Cache Data, which caches the data, and Cache Path, which caches the data path. After analyzing the performance of those two schemes, we propose a hybrid approach (Hybrid Cache), which can further improve the performance by taking advantage of Cache Data and Cache Path while avoiding their weaknesses. Cache replacement policies are also studied to further improve the performance. Simulation results show that the proposed schemes can significantly reduce the query delay and message complexity when compared to other caching schemes.

• IEMEK Journal of Embedded Systems and Applications
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• v.13 no.3
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• pp.151-160
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• 2018

NAND flash memories have the advantages of fast access speed, high density and low power consumption, thus they have increasing demand in embedded system and mobile environment. Despite the low power and fast speed gains of NAND flash memory, DRAM disk buffers were used because of the performance load and limited durability of NAND flash cell. However, DRAM disk buffers are not suitable for limited energy environments due to their high static energy consumption. In this paper, we propose WAP-LRU (Write pattern Analysis based Placement by LRU) hybrid disk buffer management policy. Our policy designates the buffer location in the hybrid memory by analyzing write pattern of the workloads to check the continuity of the page operations. In our simulation, WAP-LRU increased the lifetime of NAND flash memory by reducing the number of garbage collections by 63.1% on average. In addition, energy consumption is reduced by an average of 53.4% compared to DRAM disk buffers.