• Proceedings of the IEEK Conference
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• 2002.07c
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• pp.1459-1462
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• 2002

Emergence of the fourth generation mobile communication system (4G system) is now in its dawn. This paper pro- poses a perspective framework on the 4G system, and discusses system aspects of radio access technologies. The focus of the paper is to define the scope and features of the 4G system in an overall system/network viewpoint. From the foreseeable development trends, it is highly expected that whatever emerges in the 4G system will be some kind of constantly evolving and grand recursive concatenation of all the existing system/network developments.

• Journal of Information Technology Applications and Management
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• v.16 no.4
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• pp.205-222
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• 2009

Considering time-lag in the performance evaluation of information system (IS) investment is important because its effect reveals after certain period of time passed. Particularly it is more in the systems of e-government informatization projects which the amount of investment and the scale of business are huge. Many methods to solve this issue have been proposed such as system dynamics methods, simulations, structural equations etc. However, it is still difficult and unsolved problem because collecting practical data for time-lag analysis is very hard. In this paper, we analyze IS time-lag effect through factor analysis using the accumulated practical operational DB data. For the performance evaluation of the G4C system, the representative e-government web portal, we selected eleven factors reflecting time passing in G4C DB data. With these factors this paper conduct time-lag analysis in four view points. First, we conducted 'Stabilizing of G4C system' and got a result that IS is needed about three years for the stabilization. Second, we conducted 'Utilization of G4C system' and got a result that the utilization reaches appropriate level after in three years later after the introduction of G4C system. Third, we conducted 'Cost reduction effect' and got a result that cost reduction is stable in the third year after the introduction of G4C system. Lastly, we conducted 'System maturity effect' and got a result that the system reaches to the quality level that users expect after third to fourth years. According to the results of this research, we found that performance of IS improv continuously not immediately, and it needs three or four years of time-lag.

• Journal of Communications and Networks
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• v.4 no.4
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• pp.321-335
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• 2002

Emergence of the fourth generation mobile communication system (4G system) is now in its dawn. This article proposes a perspective framework on the 4G system, and discusses various kinds of system aspects and technological requirements in terms of novel service features, spectrum management, radio access technologies, wired access integration, core network, and mobile terminal. The focus of the article is to define the scope and features of the 4G system in an overall system/network viewpoint. From the foreseeable development trends, it is highly expected that whatever emerges in the 4G system will be some kind of constantly evolving and grand recursive concatenation of all the existing system/network developments.

• International journal of advanced smart convergence
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• v.4 no.2
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• pp.29-33
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• 2015

In this paper, we propose the method to improve the performance of the antenna system that contains three bands, such as Lte3G, WLAN and Lte4G. This antenna has an advantage that can cover the three different frequency bands 2.1GHz, 2.4GHz and 2.6GHz through one antenna design. The design and simulations are done using CST Microwave Studio 2014 program. The antenna is designed by using the FR-4 (lossy) substrate with the dielectric constant of er=4.3 and dielectric loss tangent 0.025. The substrate dimensions are the following; Thickness[h] is 1.6mm, Length is 90mm, and Width is 40mm. The ground is designed by using the PEC material with h=0.035mm. The patch is designed by using the copper with h=0.035mm. In the near future, we will fabricate the antenna, which we have designed, and then apply this antenna to the mobile communication system. And we will test this mobile communication system for the diverse environments.

• KSBB Journal
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• v.13 no.5
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• pp.547-553
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• 1998

For the efficient production of a new exo-polysaccharide from Ganoderma lucidum ASI 7004, the optimum conditions and methods in submerged cultivation were investigated with an airlift fermenter system. The optimum aeration rate was 2.5 Wm at the initial pH 5.0 and 28$^{\circ}C$. The increase of dissolved oxygen concentration by pure oxygen supply during cultivation did not improved the exo-polysaccaride production and the mycelial growth. The maximum exo-polysaccharide production and the mycelial growth under the optimum culture condition were obtained in media of glucose 60g/L, yeast extract 6g/L, (NH4)2HPO4 1g/L and KH2PO4 0.5g/L. Under these optimum medium and culture conditions, about 7.15g/L of exo-polysaccharide and 13.9g/L of mycelial growth were producted, respectively.

• Journal of Microbiology and Biotechnology
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• v.4 no.4
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• pp.333-337
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• 1994

In order to develop the whey beverage, we examined the optimum conditions for alcohol fermentation by Kluyveromyces tragilis ATCC 46537. The optimum conditions for alcohol production by K. fragilis ATCC 46537 were as follows; pH 4.5, $30^{\cir}C$, with a supplement of 50 g/l of lactose. To develop a continuous production of alcohol from whey, we compared batch fermentation with continuous iermentation in conjunction with UF system. Batch fermentation produced 11.0 g/l of alcohol, whereas pseudocontinuous and continuous fermentation with UF system produced 8.5 g/l of alcohol. To increase the alcohol production, we added 50 g/l of lactose to both fermentations. Batch fermentation with lactose supplement produced 15.7 g/l of alcohol and continuous fermentation with lactose supplement in conjunction with UF system produced 15.0 g/l of alcohol. These results clearly demonstrate that the UF system can be used to increase the alcohol production from whey, supplemented with exogenous lactose.

• KSBB Journal
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• v.16 no.5
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• pp.511-515
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• 2001

In this paper, we development and operated a two-stage continuous stirred tank reactor (CSTR)/trickling biofilter(TBF)system for the long-term continuous treatment of trichloroethylene (TCE) using Burkholderia cepacia G4. In this reactor system. CDTR with cell recycle from TBF was coupled to the TBF for the reactivation of the cells deactivated during TCE degradation. The critical elimination capacity was determined to be 25.3 mg TCE/L day and the reactor has been stably operated for more than 1 months, which clearly represented that CSTR/TBF system can be used for long-term treatment of TCE.

• Journal of Animal Environmental Science
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• v.4 no.1
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• pp.21-28
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• 1998

This study was carried out to estimate the economic impacts on operation cost and curtail the bulking agent between two kinds of plants in swine farms. Bulking agents and Plants have a variety of roles in the fields of the composting for livestock manure and also represent an economic problem in terms of plant operation costs and compost production. Two farms which have rotary(size of reactor : 10${\times}$35${\times}$1.5m) or bucket(size of reactor : 10${\times}$68${\times}$2m) plants were used for 24 weeks for bucket conveyor system, which are composed of refilling rice hull as a bulking agent every 3 weeks till decreasing volume, for 4 weeks for rotary conveyor system, which has continuous compost production system without refilling rice hull, respectively. Composts was produced in 24 weeks in the bucket conveyor system, in 4 weeks in the rotary conveyor system, respectively. The results are as follows : 1. The tissue change of Rice hull at the composts of 45 days pursuant to composting steps was more crumbling in bucket conveyor system than in rotary conveyor system. 2. Microbial counts of the final composts for safety and quality showed that total bacteria counts was 1.01${\times}$108 cfu/g in bucket conveyor system, 2.82${\times}$108 cfu/g in rotary conveyor system, Salmonella was 0.3${\times}$102 cfu/g in bucket conveyor system, 7.6${\times}$102 cfu/g in rotary conveyor system, colifom bacteria was 0.5${\times}$106 cfu/g in bucket conveyor system, 1.5${\times}$106cfu/g in rotary conveyor system, fungi 1.24${\times}$106 cfu/g in bucket conveyor system, 0.01${\times}$106 cfu/g in rotary conveyor system, respectively. However, Any system used in this trial could not be met the regulation of A grade compost of EPA and USA. 3. C:N ratio according to the composting was more rapidly changed in bucket conveyor system with 64.5 of 5 days compost to 25.4 of final products than in rotary conveyor system with 26.7 of 5 days compost to 25.9 of final products. 4. Based on the mechanical characteristics of plants used in trial and compared with Rotary conveyor system, the Bucket conveyor system in which has 0.72 ㎥/㎥ of bulking agent capacity per slurry could be curtailed 1.78 ㎥of rice hull for disposal of waste, 1㎥. It was proper facilities to produce composts quantitative in Rotary conveyor system, and to treat waste quantitative and obtain good results in compost quality in Bucket conveyor system.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.6
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• pp.15-23
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• 2016

In this paper we presented 4G security models in an open environment. 4G networks have still more security holes and open issues for expert to notice. In here. we show that a number of new security threats to cause unexpected service interruption and disclosure of information will be possible in 4G due mainly to the fact that 4G is an IP-based, heterogeneous network. it tells about the security issues and vulnerabilities present in the above 4G standards.. we try to present several architectures behind 4G infrastructure for example WiMAX and 3GPP LTE architecture. Finally, we point to potential areas for future vulnerabilities and evaluate areas in 4G security which warrant attention. When you make a big dada program, If you use this network architecture then you can improve your learning speed.

• Journal of the Korea Organic Resources Recycling Association
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• v.24 no.1
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• pp.31-40
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• 2016

In this study, mesophilic anaerobic digestion of source separated food waste was carried out by leachate recirculation system and methane gas was produced. Two systems - system A and B were fabricated and placed within water bath to maintain $36^{\circ}C$. Each system was comprised of an anaerobic bioreactor and a leachate tank. Leachate in bioreactor was separated through the screen located at 30 mm above the bottom and a pump was installed to transfer collected leachate to the leachate tank. Everyday, 2.5 L of the leachate was pumped from the bioreactor to the leachate tank for 30 min and transferred leachate was pumped back to the top of the bioreactor for 30min, sequentially. Source separated food waste used for this experiment was washed by water before transferring to the laboratory. Transferred food waste was warmed to $36^{\circ}C$ before being fed to bioreactors. System A was fed to 49.1 g VS (Volatile Solids) and System B was fed to 54.0 g VS at every two weeks, respectively. $NH_4{^+}-N$ and salinity were monitored to see the inhibition toward anaerobic bioreaction and it was found that concentrations of these materials were not high enough to affect the bioreaction. Although the food waste was fed biweekly for 112 days and 140 days at system A and B, respectively, there was no sludge withdrawal from each system. Average methane productions rates were 0.439 L $CH_4/g$ VS and 0.368 L $CH_4/g$ VS for system A and B, respectively.