• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.1
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• pp.14-21
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• 2011

A 10b 500MS/s $0.13{\mu}m$ CMOS ADC is proposed for 4G wireless communication systems such as a LTE-Advanced and SDR The ADC employs a calibration-free single-channel folding architecture for low power consumption and high speed conversion rate. In order to overcome the disadvantage of high folding rate, at the fine 7b ADC, a cascaded folding-interpolating technique is proposed. Further, a folding amplifier with the folded cascode output stage is also discussed in the block of folding bus, to improve the bandwidth limitation and voltage gain by parasitic capacitances. The chip has been fabricated with $0.13{\mu}m$ 1P6M CMOS technology, the effective chip area is $1.5mm^2$. The measured results of INL and DNL are within 2.95LSB and l.24LSB at 10b resolution, respectively. The SNDR is 54.8dB and SFDR is 63.4dBc when the input frequency is 9.27MHz at sampling frequency of 500MHz. The ADC consumes 150mW($300{\mu}W/MS/s$) including peripheral circuits at 500MS/s and 1.2V(1.5V) power supply.

• The Transactions of the Korea Information Processing Society
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• v.4 no.1
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• pp.215-223
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• 1997

The advantages of service in satellite links are representatively a long distance and large capacity transfer and simultaneous communication. And terrestrial links are of high speed and high quality data transfer Therefore a combined form of characteristics of satellite and terrestrial links is desirable to furnish a good quality service to subscribers. And in satellite links an analysis method and a simulation method of file transfer are conducted to evaluate the efficiency of file transfer. The parameters are used the message length and transmission time, and the number of chain record and transmission time. From the results of evaluation, in satellite links, it is found that when the message length is shorter than 512 bytes, the file transmission time becomes extremely long and when the message length is set at 1024 bytes, the file transmission time abruptly increase from 2048 bytes. Also it is confirmed that when the number of chain record is under 15, the file transmission time becomes extremely long and if the number increase up to 90,the time becomes gradually short and over 90,it becomes constant.Therefore,from the result of file transmission in th case of utilizing satelite links,it is confirmed that the optimum message length in the minmum transmission time is present closely at 1024 bytes.Also it is confirmed that when the satelite transmission sped becoms smaller from 24kbps to2400bps,the optimum message length also becomes smaller from 640 bytes to 256bytes.

• The KIPS Transactions:PartD
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• v.10D no.4
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• pp.591-602
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• 2003

Delay and discontinuance phenomenon of service are cause by sudden increase of the network communication amount and the quantity consumed of resources when Internet users are driven excessively to a conventional single large database sewer. To solve these problems, spatial database cluster consisted of several single nodes on high-speed network to offer high-performance is risen. But, research about spatial join operation that can reduce the performance of whole system in case process at single node is not achieved. So, in this paper, we propose efficient parallel spatial join processing method in a spatial database cluster system that uses data partitions and replications method that considers the characteristics of space data. Since proposed method does not need the creation step and the assignment step of tasks, and does not occur additional message transmission between cluster nodes that appear in existent parallel spatial join method, it shows performance improvement of 23% than the conventional parallel R-tree spatial join for a shared-nothing architecture about expensive spatial join queries. Also, It can minimize the response time to user because it removes redundant refinement operation at each cluster node.

• KIPS Transactions on Computer and Communication Systems
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• v.2 no.9
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• pp.381-392
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• 2013

During the last decade, the multitude of advances attained in terminal computers, along with the introduction of mobile hand-held devices, and the deployment of high speed networks have led to a recent surge of interest in Quality of Service (QoS) for video applications. The main difficulty is that mobile devices experience disparate channel conditions, which results in different rates and patterns of packet loss. One way of making more efficient use of network resources in video services over wireless channels with heterogeneous characteristics to heterogeneous types of mobile device is to use a scalable video coding (SVC). An SVC divides a video stream into a base layer and a single or multiple enhancement layers. We have to ensure that the base layer of the video stream is successfully received and decoded by the subscribers, because it provides the basis for the subsequent decoding of the enhancement layer(s). At the same time, a system should be designed so that the enhancement layer(s) can be successfully decoded by as many users as possible, so that the average QoS is as high as possible. To accommodate these characteristics, we propose an efficient transmission scheme which incorporates SVC-aware dual-channel repetition to improve the perceived quality of services. We repeat the base-layer data over two channels, with different characteristics, to exploit transmission diversity. On the other hand, those channels are utilized to increase the data rate of enhancement layer data. This arrangement reduces service disruption under poor channel conditions by protecting the data that is more important to video decoding. Simulations show that our scheme safeguards the important packets and improves perceived video quality at a mobile device.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.1
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• pp.39-47
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• 2005

The range of hardware implementation increases in communication systems as high-speed processing is required for high data rate. In the broadband wireless access (BWA) system based on IEEE standard 802.16 the functions of higher part in the MAC layer to Provide data needed for generating MAC PDU are implemented in software, and the tasks from formatting MAC PDUs by using those data to transmitting the messages in a modem are implemented in hardware. In this paper, the interface hardware for efficient message exchange between MAC and PHY layers in the BWA system is designed. The hardware performs the following functions including those of the transmission convergence(TC) sublayer; (1) formatting TC PDU(Protocol data unit) from/to MAC PDU, (2) Reed-solomon(RS) encoding/decoding, and (3) resolving DL MAP and UL MAP, so that it controls transmission slot and uplink and downlink traffic according to the modulation scheme of burst profile. Also, it provides various control signal for PHY modem. In addition, the truncated binary exponential backoff (TBEB) algorithm is implemented in a subscriber station to avoid collision on contention-based transmission of messages. The VLSI architecture performing all these functions is implemented and verified in VHDL.

• Journal of the Economic Geographical Society of Korea
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• v.3 no.2
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• pp.5-22
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• 2000

Manufacturing industry in Chonbuk region has experienced relatively consistent increase during period 1975-1999. The importance of labor-intensive sectors such as textiles and clothing, wood and furniture, and food and drink, which had been traditionally major sectors in this region, has declined over the same period. On the other hand, the shares of more complex sectors like automobile, chemistry, communication equipment, and other machinery have gone up. The structural change of Chonbuk manufacturing industry, with increasing diversity, follows the national trend of industrial development, based on national industrial policies. but the speed and level of the change has been slow and low in terms of the national standard of manufacturing development, especially with the weak development of high technology industry. In Chonbuk, the spatial distribution of manufacturing industry has shown a high degree of concentration. Although spatial concentration is apparent in the central area including the cities of Chonju, Iksan, and Kunsan, new tendency towards industrial decentralization within this area has been found. The tendency means manufacturing development at the fringe of this area. There is another tendency towards industrial dispersion into the cities of Kimje and Jeongup close to this central area. The spatial dispersion of manufacturing industry has been accelerated in the form of increasing external investment. But despite the tendency of the spatial dispersion, the development of manufacturing industry in the rest of the region still remains a marked inferiority.

• Journal of Digital Convergence
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• v.13 no.5
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• pp.177-185
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• 2015

The gender difference in social roles affects digital devices' utilization differences in man and woman even in the 21st Century. Prior studies analyze the digital divide (genders, ages, etc.) from the assessment perspectives of digital equipment, such as PCs. In the area of high speed internet, most functions of PCs have been replaced with smartphones, and around 80% of the mobile phone users adopt smartphones. Subsequently the inequality of physical access to the digital devices is no longer a criterion for digital divide. The focus on digital divide should be shifted from the physical access to other factors, such as socio-technical or socio-cultural ones. This paper examines utilization of women's digital equipment, in particular, preparing for tourism activities, which is popular but sensitive to the technology. A survey was conducted with participants of [Suncheon Garden Expo] 2013. The results of this study capture the inactive use of digital devices particularly women over 50s. This phenomenon (high utilization of the digital devices for social or informative purposes, but low utilization of the digital payment) implies other aspects of Korean women (economic independence, low self-assertion, technical difficulties, etc.), which is considered from the socio-technological convergence perspective. This study also has a practical implication on the side of the digital device developers as well as marketing, where the qualitative communication is likely to be incorporated for the women over 50s.

• Journal of the Korea Society of Computer and Information
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• v.17 no.12
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• pp.241-249
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• 2012

The rapid development of the current information and communication brings big changes and progress in the health service delivery system. And it is becoming the worldwide trend increasingly. As the name of medical information, by more rapid, detail and more quickly to the patients and diagnosis of the disease it provides not only a high level of health care services but also hospitals and related institutions are making increase the efficiency of the work. Among them, the Telemedicine, that system has many advantage which can expect the shorten the waiting time and the uniform high level of medical, etc. without visiting medical institutions. Especially, the most advantage is it can increase the accessibility of information about extensive medical, without regard to the time and place. But this is the reality, which compared speed the development of modern science and technology with lack of operational regulations and mindset. Current in our Medical Law, it regulates the Telemedicine, but it has Institutional, facility, and environmental constraints. Because, there is no detailed legal relationship. And it takes that in terms of a special form called by a non-face-to-face contact with medical practice rather than the scene. Therefore, in this paper will find a way out to activate the Telemedicine by presupposes the development potential is infinite and find the legal issues and improvements.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.11A
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• pp.1827-1840
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• 2001

In digital data transmission/storage systems, the compensation for channel distortion is conducted normally using a training sequence that is known a priori to both the sender and receiver. The use of the training sequences results in inefficient utilization of channel bandwidth. Sometimes, it is also impossible to send training sequences such as in the burst-mode communication. As such, a great deal of attention has been given to the approach requiring no training sequences, which has been called the blind equalization technique. On the other hand, to utilize the limited bandwidth effectively, the concept of partial response (PR) signaling has widely been adopted in both the high-speed transmission and high-density recording/playback systems such as digital microwave, digital subscriber loops, hard disk drives, digital VCRs and digital versatile recordable disks and so on. This paper is concerned with blind adaptive equalization of partial response channels whose transfer function zeros are located on the unit circle, thereby causing some problems in performance. Specifically we study how the problems of blind channel equalization associated with the PR channels can be improved. In doing so, we first discuss the existing methods and then propose new structures for blind PR channel equalization. Our structures have been extensively tested by computer simulation and found out to be encouraging in performance. The results seem very promising as well in terms of the implementation complexity compared to the previous approach reported in literature.

• Journal of Software Assessment and Valuation
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• v.16 no.1
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• pp.55-63
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• 2020

Lasers for optical broadband communication systems should have excellent frequency selectivity and modal stability. DFB lasers have low lasing frequency shift during high speed current modulation. In this paper, when a refractive index grating and a gain grating are simultaneously present in a DFB laser having a wavelength of 1.55 ㎛, the dielectric film is coated so that reflection does not occur on the right mirror surface, so that ρ_r=0. For the first mode, which requires a minimum gain at the threshold, the beam distribution of the oscillation mode in the longitudinal direction and the radiated power ratio P_l/P_r were analyzed and compared for the cases of the phase of ρ_l=π and π/2. If the phase of ρ_l=π, in order to obtain a low threshold current and high frequency stability, κL should be greater than 8. In the case of the phase of ρ_l=π/2, for low threshold current, κL is necessary to be 1.0, where the oscillation frequency coincides with the lattice frequency. DFB lasers with an anti-reflection coated mirror have excellent mode selectivity than 1.55um DFB lasers with two mirror facets