• The KIPS Transactions:PartB
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• v.11B no.6
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• pp.691-700
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• 2004

This paper proposes a user's mobility based cooperative proxy caching policy for effective resource management of continuous media objects in mobile environments. This policy is different from the existing proxy caching policies in terms of how to exploit users' mobility. In other words, existing caching policies work based on the information about objects by referring to user's requests within a specified domain whereas the proposed caching policy runs by utilizing a number of user's requests across several domains. So, the proposed policy is applicable to random requests in mobile environments Moreover, we also propose a replacement policy based on weights and playback time. To check the efficiency of the proposed caching policy, the proposed replacement policy is run with different size of caching unit object or segment. The result of performance analyze tells what a ratio of user's mobility is are major factors for the efficient operation of the cooperative caching.

• Journal of the Korea Society of Computer and Information
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• v.27 no.4
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• pp.223-229
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• 2022

The emergence of smartphones is creating a faster and easier digital communication society along with the existing Internet. Among the various methods of communication, the smart notification is most often used in early childhood education institutions for information exchange between parents, teachers and directors. And the notification helps parents understand the development status and curriculum of infants more easily. Therefore, this paper developed an integrated infant management system based on a web-based platform and a mobile app platform for exchanging various information on infants management between directors, teachers and parents. Through the established system, the director, teachers, and parents can check the information they need at any time, and it is possible to provide a mobile service environment where multiple guardians can safely take care of one infant. In addition, multiple guardians can provide appropriate feedback information through the collection and analysis of various data by using the infant and toddler integrated management system. In the future, if the functions provided based on the smartphone app are configured according to the user, it is expected that it will be able to expand from daycare centers to educational institutions.

• IEMEK Journal of Embedded Systems and Applications
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• v.11 no.6
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• pp.325-334
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• 2016

Recently, Open Computing Language (OpenCL) has been proposed to provide a framework that supports heterogeneous computing platforms. By using an OpenCL framework, digital communication systems can support various protocols in a unified computing environment to achieve both high portability and high performance. This article introduces a parallel software decoder of Low Density Parity Check (LDPC) codes for China Multimedia Mobile Broadcasting (CMMB) on a heterogeneous platform. Each step of LDPC decoding has different parallelization characteristics. In this paper, steps suitable for task-level parallelization are executed on the CPU, and steps suitable for data-level parallelization are processed by the GPU. To improve the performance of the proposed OpenCL kernels for LDPC decoding operations, explicit thread scheduling, loop-unrolling, and effective data transfer techniques are applied. The proposed LDPC decoder achieves high performance by using heterogeneous multi-core processors on a unified computing framework.

• Information Systems Review
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• v.8 no.2
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• pp.1-15
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• 2006

Schedule Management for outside duty personnels and their groups is fairly difficult since they spend most of their time on working outside individually rather than inside office. Everytime when schedule change for personnels or their groups is needed, it is necessary to call every personnel in order to notify the schedule change. It would be much easier to handle the schedule management problem if outside duty personnels are able to download schedule of their groups(and, upload their schedule) using their mobile communication devices such as PDAs. In this paper, using a data synchronization protocol in mobile communication environments, a schedule management system for outside duty personnels is designed and implemented. Data synchronization in mobile communication environments is a process of maintaining consistency between data stored in mobile devices and data stored in a (central) server at office. In other words, using SyncML data synchronization protocol proposed by OMA(Open Mobile Alliance) as an open standard for data synchronization in mobile communication environments, a schedule management system for outside duty personnels which allows them to check schedule of their groups and to notify their schedule to their groups at anytime anyplace is designed and implemented.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.1
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• pp.22-30
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• 2011

In this paper, we propose a memory efficient multi-rate Low Density Parity Check (LDPC) decoder for China Mobile Multimedia Broadcasting (CMMB). We find the best trade-off between the performance and the circuit area by designing a partially parallel decoder which is capable of passing multiple messages in parallel. By designing an efficient address generation unit (AGU) with an index matrix, we could reduce both the amount of memory requirement and the complexity of computation. The proposed regular LDPC decoder was designed in Verilog HDL and was synthesized by Synopsys' Design Compiler using Chartered $0.18{\mu}m$ CMOS cell library. The synthesized design has the gate size of 455K (in NAND2). For the two code rates supported by CMMB, the rate-1/2 decoder has a throughput of 14.32 Mbps, and the rate-3/4 decoder has a throughput of 26.97 Mbps. Compared with a conventional LDPC for CMMB, our proposed design requires only 0.39% of the memory.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.3
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• pp.781-793
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• 2010

Recently, owing to the development of ubiquitous sensor network and mobile communication technologies, many studies on healthcare system are being carried out. In this paper, we have designed and implemented a mobile u-Healthcare system based on sensor network. The u-Healthcare system is composed of three components: wireless sensor network at home, healthcare center located at remote site, and gateway which relays sensing physiological signals to healthcare center. In order to measure patient's physiological signal three sensors are used: three channel ECG sensor, pulse oximeter, and blood pressure sensor. Each sensor is mounted on a mote which can send gathered signal to the base node using Zigbee communication protocol. Once the base node receives physiological signal from each sensor, the client in the base node transfers the signal to the healthcare center. The received physiological signal at the healthcare center is analyzed and processed using various algorithms. The processed results are compared to the standard healthcare database and appropriate treatment including dietetics and exercise cure would be sent to the patient as feedback using SMS message or healthcare center web site. Each patient can check and manage one's health state every day using the healthcare system and gain a recovery under the treatments from minor health problems.

• The Journal of the Korea Contents Association
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• v.11 no.9
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• pp.293-301
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• 2011

This study intends to deduce various purchase intention influential factor for mobile phone and thereby to clarify the causal relationship between these factors and purchase intention. As a result of the analysis of this study, we could know that first, when the impact about brand attitude on consumers is bigger, a positive affect is induced and the effects about personalization interface were also positive. Second, we could know that when the innovative tendency of consumers is stronger, they experience positive affects and the impact on personalization interface was also effective. However, it was clarified that when the innovative tendency is stronger, the impact on price gets smaller. Third, when the imitation tendency of consumers was higher, positive affects were induced, and when the interest in personalization interface of consumers was higher, positive affects were induced and the interest in price also gets higher. Fourth, we could check the influence of affect in the purchase intention of mobile phones.

• Journal of Advanced Navigation Technology
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• v.22 no.5
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• pp.485-489
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• 2018

For the construction of smart factory that are part of the Fourth Industrial Revolution, data from the production environments and production machines should be collected, analyzed, and feedback should be given to predict when failures take place or parts should be replaced. For this purpose, a system that monitors the production environments and the status of the production machines are required. In this paper, the monitoring system for mobile devices and PC is implemented by collecting environmental data from production sites and sensor data of production machine using LoRa, a low-power wireless communication technology. On the mobile devices, production environments and vibration data can be displayed in real time. In PC monitoring program, sensor data can be displayed graphically to check standard deviation and data variation. The implemented system is used to collect data such as temperature, humidity, and atmospheric pressure of the production environment, and vibration data of production machines.

• Journal of Korea Society of Digital Industry and Information Management
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• v.9 no.3
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• pp.119-127
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• 2013

The merits of Smartphone are portability, convenience and especially a lot of information can be stored in the device. Especially in Smartphone, users can install programs that cannot install to normal cell phone and users can use many different services through these Smartphone programs. Also Smartphone can connect to Internet through network, so it can access information anytime, anywhere easily. Security of personal information and variety of information which stored in Smartphone are in risk. In Chapter 2 of thesis, it will discuss the definition and features of the Smartphone and market trends. In Chapter 3 of thesis, it will discuss security vulnerabilities of Smartphone and it will analyze and research security vulnerabilities of Smartphone in Chapter 4. In conclusion, it will check users' identification twice in useful application especially application that relate to finance and mobile payment. By checking users' identification several times, it will help to defend from security threats. Users can use Smartphone safely and convenience by know how to prevent from mobile hacking for personal and private information. the quality of APIs matching by the clustering and hierarchical relationships mechanism.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.9C
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• pp.801-809
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• 2007

LDPC Low Density Parity Check) code, which is an error correcting code determined to be applied to the 4th generation mobile communication systems, requires a heavy computational complexity due to iterative decodings to achieve a high BER performance. This paper proposes an algorithm to reduce the number of decoding iterations to increase performance of the decoder in decoding latency and power consumption. Measuring changes between the current decoded LLR values and previous ones, the proposed algorithm predicts directions of the value changes. Based on the prediction, the algorithm inverts the sign bits of the LLR values to speed up convergence, which means parity check equation is satisfied. Simulation results show that the number of iterations has been reduced by about 33% without BER performance degradation in the proposed decoder, and the power consumption has also been decreased in proportional to the amount of the reduced decoding iterations.