• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.5A
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• pp.475-483
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• 2007

Recently, consumers demand high-quality wireless multimedia services via terrestrial and satellite network. And the interest for new services to sustain its successful commercial deployment grows tremendously. So, the MIMO schemes, such as STCs, MRC, has been used for realizing high reliability. However, MIMO schemes has some limitations. MIMO scheme needs more size, cost, and hardware complexity to employ additional antennas. Moreover, sufficient spaces between antennas are required to guarantee the independence of each channel and the devices which use multiple antennas should be enlarged. A cooperative transmission technique which is detect and forward type applying virtual MIMO with STBC matrix in DVB-RCT(Digital Video Broadcasting with Return Channel via Terrestrial) system based on OFDMA is also proposed.

• JSTS:Journal of Semiconductor Technology and Science
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• v.15 no.4
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• pp.445-453
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• 2015

A fully integrated cost-effective and low-power single chip Lithium-Ion (Li-Ion) battery protection IC (BPIC) for portable devices is presented. The control unit of the battery protection system and the MOSFET switches are integrated in a single package to protect the battery from over-charge, over-discharge, and over-current. The proposed BPIC enters into low-power standby mode when the battery becomes over-discharged. A new auto release function (ARF) is adopted to release the BPIC from standby mode and safely return it to normal operation mode. A new delay shorten mode (DSM) is also proposed to reduce the test time without increasing pin counts. The BPIC implemented in a $0.18-{\mu}m$ CMOS process occupies an area of $750{\mu}m{\times}610{\mu}m$. With DSM enabled, the measured test time is dramatically reduced from 56.82 s to 0.15 s. The BPIC chip consumes $3{\mu}A$ under normal operating conditions and $0.45{\mu}A$ under standby mode.

• KIEAE Journal
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• v.13 no.4
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• pp.63-68
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• 2013

On the electricity consumption in Korea, the lighting sector takes about 17% of annual total electricity consumptions. In the midst of higher interests on energy conservation measures, design and choice of energy-saving lighting fixtures have been more important. With growth of technology-intensive industries like advanced material, semiconductor, and biotechnology from the 1980s, needs for clean room and thus illumination at clean rooms have been increased. In this paper, development, specification, and features of a Teardrop LED(hereinafter TD LED) lighting fixture as replacement of Teardrop florescent lighting one that has been popularly installed at clean rooms were presented. Also we performed the economic analysis of return on investment(ROI) about energy savings by the installation of the TD LED lighting fixture at a new-built clean room. The economic analysis showed that the new-developed TD LED lighting fixture would be able to withdraw the initial installation cost within 4 years. Lastly, improvement directions and development plans of the next TD LED lighting fixture for wider applications at clean rooms were described.

• Journal of Korean Society of Water and Wastewater
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• v.22 no.3
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• pp.329-336
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• 2008

The pilot study was conducted to evaluate the applicability of air flotation(AF) processes combined with biological nutrient removal(BNR) for the retrofitting of conventional wastewater treatment facilities. The BNR system was operated in pre-denitrification and intermittent aeration; developed ceramic membrane diffusers were installed to separate the solid-liquid of activated sludge at the bottom of a flotation tank. Before performing a pilot scale study, the size distribution of microbubbles generated by silica or alumina-based ceramic membrane diffusers was tested to identify the ability of solid-liquid separation. According to the experimental results, the separation and thickening efficiency of the alumina-based ceramic membrane diffuser was higher than the silica-based ceramic membrane diffuser. In a $100m^3/d$ pilot plant, thickened and return sludge concentration was measured to be higher than 15,000mg SS/L, therefore, the MLSS in the bioreactor was maintained at over 3,000mg SS/L. The effluent quality of the AF-BNR process was 4.2mg/L, 3.7mg/L, 10.6mg/L and 1.6mg/L for $BOD_5$, SS, T-N and T-P, respectively. Lastly, it was revealed that the unit treatment cost by flotation process is lower than about $1won/m^3$ compared to a gravity sedimentation process.

• Korean Journal of Agricultural Science
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• v.22 no.2
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• pp.209-222
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• 1995

To mitigate the development gap between urban and rural area, the government has implemented project planning as the Rural Integrated Development in each Gun level since 1986. On account of shortage of the development fund, the government had changed the Gun level development into Myeon level development so called the Rural Central Settlement Zone Development. The government had started nine pilot projects throughout Korea from 1990. This study is aimed at identifing problems that found in the course of implementation of the projects and recommending the new direction of the successful implementation of the projects in the future. The problems and directions found in the cource of project implementation were as follows: 1. Project implementation by investment priority considering economic and financial rate of return should be made. 2. Objective project planning should be made. 3. Equal allocation of the limited investment fund by group interest and egoism should be prohibited. 4. Enforcement of special man power should be taken into account. 5. Unification of the diversified existing terms and conditions of loans for house construction and improvement. 6. Road development oriented budget allocation should be improved. 7. Sufficient development fund should be procured considering the present rate of sufficiency of the project cost as 36%. 8. Sufficient supply of the credit loans for improvement of living environment of the farmers should be realized. 9. Rational implementation planning in connection with farm household income source development should be made.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.1
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• pp.85-92
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• 2011

Main characteristic in railroad is the guided movement of the wheel by the track through a metal-to-metal contact, conferring to the rail vehicle a single degree of freedom. There are defects such as head check, shelling, corrugation, squats etc in surface of the rail by interface between the wheel and rail. These defects bring about reducing the life-cycle of rails and track components and increasing noises. In case of bad conditions, it is possible to happen to full-scale accident such as derailment. Recently, the track capacity has been increased for increasing speed and operation efficiency. So, maintenance and indirect cost have been increased. Currently, a coating method of rail construction is proposed by using the ceramics in Korea. Rails are used as the earth in electrical railroad systems. Currently traction return current is flowed through wheels of trains. In case of rails coated, problems are caused in the contact power between wheel and coating material of spray. In this paper, electric model is presented in the AT feeding method. In case of rails coated, electric model is presented. Also, standard resistance of the ceramic is demonstrated by contact power between wheel and coating material of spray.

• Journal of the Earthquake Engineering Society of Korea
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• v.23 no.6
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• pp.329-339
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• 2019

The strategy for the management of earthquakes is shifting from post recovery to prevention; therefore, seismic performance management requires quantitative predictions of damage and the establishment of strategies for initial responses to earthquakes. Currently, seismic performance evaluation for seismic management in Korea consists of two stages: preliminary evaluation and detailed evaluation. Also, the priority of seismic performance management is determined in accordance with the preliminary evaluation. As a deterministic method, preliminary evaluation quantifies the physical condition and socio-economic importance of a facility by various predetermined indices, and the priority is decided by the relative value of the indices; however, with the deterministic method it is difficult to consider any uncertainty related to the return-year, epicenter, and propagation of seismic energy. Also this method cannot support tasks such as quantitative socio-economic damage and the provision of data for initial responses to earthquakes. Moreover, indirect damage is often greater than direct damage; therefore, a method to quantify damage is needed to enhance accuracy. In this paper, a Seismic Risk Assessment is used to quantify the cost of damage of road facilities in Pohang city and to support decision making.

• Asian-Australasian Journal of Animal Sciences
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• v.4 no.1
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• pp.85-90
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• 1991

Weaner heifers were set stocked at 4/ha on a grass-legume pasture in South Sulawesi, Indonesia, and either unsupplemented (Control) or for 338 days given daily supplements of one of, rice bran (RB) supplied at 1 kg/animal/d, molasses/urea (MU) or 0.5 RB + 0.5 MU (MURB) the amounts of which were adjusted to give similar energy intakes. There were 20 animals in each treatment. A drought resulted in low pasture availability for about half the supplementation period. The LWG per animal in the MURB treatment was 85 kg above that of the control and this was significantly greater (p < 0.01) than those for MU (62.0 kg) or RB (56.2 kg) although the economics favoured the gains from RB which returned over three times the cost of the supplement. Costs could be reduced by supplementing only at times of maximum undernutrition, but such a strategy is of doubtful value in this situation as there was no compensatory LWG and a similar rate of economic return was maintained throughout the period. The results suggest that additional benefits from the supplementation may be improved reproductive performance and more efficient use of pasture.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.11B
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• pp.693-699
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• 2007

In this Paper we present analysis of efficiency for various encapsulation methods to transport IP datagram over terrestrial digital multimedia broadcasting (T-DMB). The multimedia broadcasting system transmitted in one-way needs the data reliability for efficient transmission. And then It is able to select the independent data service using If encapsulation over T-DMB. We examine the compatibility in adopting T-DMB and the overhead of transmission occurring encapsulation. it also needs the full analysis of data framing because the cost of return channel is relatively higher. We do analysis based on theoretical calculation and propose an efficient, reliable and adaptable method in T-DMB.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.3
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• pp.1171-1180
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• 2021

This study aims to investigate the impact of the multimarket contract on risk-adjusted profitability. Risk-adjusted profitability is measured in terms of risk-adjusted return on assets. This study employs dynamic panel data of 27 commercial banks in Vietnam using the GMM estimator to test the multimarket contact hypothesis in the Vietnamese banking sector. The results show that there is a negative impact of multimarket contact on the profitability of banks. Multimarket contact, deposit to asset ratio, non-interest income to total income, GDP growth rate, Worldwide Governance Indicator (WGI), and operating cost to assets are the major determinants of risk-adjusted profitability of commercial banks. Our main findings show that Vietnamese banks' focus to increase the multimarket contact may lead to lower profitability and there is evidence that supports theory predictions, since the average number of contacts among banks, bank size, and capitalization are positively related to risk-adjusted profitability. The study has policy implications for commercial banks in that they should not only focus on interest as a source of income and diversify their income source from non-interest income as well since it helps to improve risk-adjusted profitability for them.