• Journal of the Korea Society of Computer and Information
• /
• v.16 no.3
• /
• pp.17-25
• /
• 2011

Green IT, composed term with Green and Information Technology(IT), use IT for energy savings and carbon emission reductions. Green IT went beyond the scope of greening IT, and recently it's concept is expanded as far as counterplan of climate change including greening other industries by IT. 85% of total greenhouse gas emissions from the energy sector and 20% of them comes from transport parts, so it is time to research IT for automotive industry. In this paper, we take up the knowledge based fuzzy logic to provide life cycle analysis associated with greenhouse gas emissions for industry produced warranty claims frequently such as automobile industry. We propose a analysis method of warranty claims using expert knowledge about the warranty in car exhaust systems related to greenhouse gas emissions, past test results of malfunction, analysis of past field data, and warranty data. Furthermore, we propose life knowledge-based GWS (Greenery Warranty System). We demonstrate the applicability of IT in eco-friendly automotive industry by implementing knowledge-based fuzzy logic and applying.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.27 no.10
• /
• pp.892-899
• /
• 2016

In this paper, an X-band 50 W internally matched power amplifier is designed and fabricated using an $80{\times}150{\mu}m$ GaN HEMT that is developed by the $0.25{\mu}m$ GaN HEMT process of ETRI. The optimum source and load impedances are experimentally extracted from the loadpull measurement using impedance-transform-prematching circuits, and the transistor performance is predicted. The power performance of the internally matched power amplifier, whose matching circuits are fabricated on a substrate with ${\varepsilon}_r$ of 10.2, is measured under the pulsed mode of $100{\mu}s$ pulse period and 10 % duty cycle, and the best output power of 47.46 dBm(55.5 W) and the power-added efficiency of 46.6 % are obtained at 9.2 GHz. The output power of 47~47.46 dBm(50~55.7 W) is measured in 9.0~9.5 GHz, and the power-added efficiency is measured to be greater than 43 % in 9.0~9.3 GHz and above 36 % in 9.4~9.5 GHz.

• Journal of KIISE:Databases
• /
• v.36 no.1
• /
• pp.8-21
• /
• 2009

A wireless sensor network is a computer network which consists of spatially distributed devices, called sensor nodes. In wireless sensor networks, energy efficiency is a key issue since sensor nodes must resides upon limited energy. To retrieve sensor information without dealing with the network issues, a sensor network is treated as conceptual database on which query can be requested. When multiple queries are requested for processing in a wireless sensor network, energy consumption can be significantly reduced if common partial results among similar queries can be effectively shared. In this paper, we propose an energy efficient multi-query processing technique based on the coverage relationship between multiple queries. When a new query is requested, our proposed technique derives an equivalent query from queries running at the moment, if it is derivable. Our technique first computes the set of running queries that may derive a partial result of the new query and then test if this set covers all the result of the new query attribute-wise and tuple-wise. If the result of the new query can be derived from the results of executing queries, the new query derives its result at the base station instead of being executed in the sensor network.

• The KIPS Transactions:PartC
• /
• v.15C no.4
• /
• pp.273-280
• /
• 2008

In WSN(Wireless Sensor Network) many routing algorithms such as LEACH, PEGASIS and PEDEP consisting of sensor nodes with limited energy have been proposed to extend WSN lifetime. Under the assumption of perfect fusion, these algorithms used convergecast that periodically collects sensed data from all sensor nodes to a base station. But because these schemes studied less energy consumption for a convergecast as well as fairly energy consumption altogether, the minimum energy consumption for a convergecast was not focused enough nor how topology influences to energy consumption. This paper deals with routing topology and energy consumption for a single convergecast in the following ways. We chose major WSN topology as MSC(Minimum Spanning Chain)s, MSTs, PEGASIS chains and proposed LECSEN chains. We solved the MSC length by Linear Programming(LP) and propose the LECSEN chain to compete with MST and MSC. As a result of simulation by Monte Carlo method for calculation of the topology length and standard deviation of link length, we learned that LECSEN is competitive with MST in terms of total energy consumption and shows the best with the view of even energy consumption at the sensor nodes. Thus, we concluded LECSEN is a very useful routing topology in WSN.

• Journal of Korea Water Resources Association
• /
• v.51 no.1
• /
• pp.61-70
• /
• 2018

This study examined how to determine the optimal sediment level in dam reservoir for efficient plan and operation of dam. Currently, Korea is applying a horizontally accumulated method for sediment level estimation for the safety design of dam and so the method estimated relatively higher level than others. However, the sediment level of dam reservoir should be accurately estimated because it is an important factor in assessing life cycle of a dam. The sediment level in dam reservoir can be determined by SED-2D model linked with RMA-2, horizontally accumulated method, area increment method, and empirical area reduction method. The estimated sediment level from each method was compared with the observed sediment level measured in 2007 in Imha dam reservoir, Korea and then the optimal method was determined. Also, the future sediment level was predicted by each method for the future trend analysis of sediment level. As the results, the most accurate sediment level was estimated by the empirical area reduction method and the future trend of sediment level variation followed the past trend. Therefore, we have found that the empirical area reduction method is a proper one for more accurate estimation of sediment level and it can be validated by the results from a numerical model of SED-2D linked with RMA-2 model.

• Journal of Wetlands Research
• /
• v.15 no.1
• /
• pp.9-17
• /
• 2013

Scirpus planiculmis dominated in Nakdong river estuary is known as food for birds visiting to Nakdong river estuary and plays an important role in material cycle and food web, while repeating growth and production, decomposition process in 1-year interval. Therefore, if it is able to predict effectively biomass or tuber production of Scirpus planiculmis which is food source for estuarine organisms or birds, it can provide very useful information on the Nakdong river estuary management. In this study, regression equation that can predict the tuber production, food for birds, was obtained using initial density of Scirpus planiculmis that can minimize the disturbance of ecosystem and is faster and easier. The correlation analysis results show that density, biomass and tuber production have liner relationship(p<0.001) with 0.6103~0.9950 of correlation coefficients. In addition, the regression equations have high coefficients of determination of 0.3696~0.7145 and it shows that it is able to predict biomass or tuber production while using the estimated regression equation obtained from relationship among the initial density, biomass and tuber production. The results of this study are expected to utilize effectively the management of estuary ecosystem such as management on food source for migratory birds visiting to Nakdong river estuary.

• The Mathematical Education
• /
• v.59 no.1
• /
• pp.17-29
• /
• 2020

The purpose of this study is to analyze the teacher's discourse structure of teachers according to the interaction pattern between teacher and student in the process of mathematization. To achieve this goal, we observed a semester class (44 lessons) of an experienced teacher who had practiced teaching methods for promoting student engagement for more than 20 years. Among them, one lesson case would be match the teacher's intention and the student's response and the other one lesson case would be to mismatch between the teacher's intention and the student's response was analyzed. In other words, in the process of mathematization based on students' engagement, the intention of the teacher and the reaction of the student was determined according to the cases where students did not make an error and when they made an error. A methodology used to develop a theory based on data collected through classroom observations(grounded theory). Because the purpose of the study is to identify the teacher's discourse structure to help students' mathematization, observe the teacher's discourse and collect data based on student engagement. Based on the teacher's discourse, conceptualize it as a discourse structure for students to mathematization. As a result, teacher's discourse structure had contributed to the intention of the teacher and the reaction of the student in the process of mathematization. Based on these results, we can help the development of classroom discourse for mathematization by specifying the role of the teacher to help students experience the mathematization process in the future.

• Journal of fish pathology
• /
• v.23 no.3
• /
• pp.303-311
• /
• 2010

Our previous finding summarizing that larval sieving process is inevitable but triggers the outbreak of scutica-like ciliates (SLCs) in the seed production of Patinopecten yessoensis urged further study to determine best suggestable sieving interval in an agreeable range of water quality. In the mass seed production of the scallop, SLC outbreak was closely related to the larval sieving in which larvae were drained on the basis of every 3-day (5T), 5-day (3T), 7-day (2T), or 9-day (1T) from culture tanks onto a mesh screen and placed back into new water in cleaned tanks. The larval performance of growth and survival was clearly dependent on the sieving intervals. It was in order of 3T, 5T, 2T, and 1T for both of growth and survival and in reverse order for SLC infection frequency, confirming that larval sieving is necessary but damageable if it overwhelms the larval resistance. Interestingly, the larval damages by the sieving persisted to their ensuing spat life in terms of nursery growth, survival, and abnormality.

• Geophysics and Geophysical Exploration
• /
• v.15 no.3
• /
• pp.129-135
• /
• 2012

The simultaneous-source full waveform inversion improves the applicability of full waveform inversion by reducing the computational cost. Since this technique adopts simultaneous multi-source for forward modeling, unwanted events remain in the residual seismograms when the receiver geometry of field acquisition is different from that of numerical modeling. As a result, these events impede the convergence of the full waveform inversion. In particular, the streamer-type data with limited offsets is the most difficult data to apply the simultaneous-source technique. To overcome this problem, the global-correlation-based objective function was suggested and it was successfully applied to the simultaneous-source full waveform inversion in time domain. However, this method distorts residual wavefields due to the modified objective function and has a negative influence on the inversion result. In addition, this method has not been applied to the frequency-domain simultaneous-source full waveform inversion. In this paper, we apply a timedamping function to the observed and modeled data, which are used to compute global correlation, to minimize the distortion of residual wavefields. Since the damped wavefields optimize the performance of the global correlation, it mitigates the distortion of the residual wavefields and improves the inversion result. Our algorithm incorporates the globalcorrelation-based full waveform inversion into the frequency domain by back-propagating the time-domain residual wavefields in the frequency domain. Through the numerical examples using the streamer-type data, we show that our inversion algorithm better describes the velocity structure than the conventional global correlation approach does.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.18 no.2
• /
• pp.77-92
• /
• 2019

TPCLT is a advanced signal system that serves twice left turn phases during the same cycle. TPCLT can be a useful where the left turn traffic volume is high and the length of the left turn lane is short. This study examined the effectiveness of TPCLT in reducing delay for a signalized three-Leg intersection and proposed the application of TPCLT signal system. 108 scenarios with different traffic volumes were created. This study analyzed the control delay of the three-Leg intersection in case TPCLT is operated and non-TPCLT is operated. As a result of analysis, it was shown that TPCLT was effective in most of the scenarios. When traffic volume ratio of the left turn is 30~40%, TPCLT was more effective at reducing the control delay. The study result shows significant delay reduction for the left turning traffic and it is approximately 50 seconds. The opposing movement's average control delay increased 2 seconds. The effect of TPCLT on the length of left turn lane was analyzed. As a result, it is found that TPCLT is effective when the length of left turn lane is 30%~60% compared to that of conventional three leg intersection operations.