• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.293-296
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• 2008

Creep and shrinkage in concrete structures are very complex phenomena in which various uncertainties exist with regard to inherent material variations as well as modeling uncertainties. The creep and shrinkage models which are capable of predicting long-term structural response are specified in design codes such as ACI 209-92, CEB-FIP Model Code 90, etc. However, in the prediction formulas of creep and shrinkage effects of concrete, various kinds of parameters are involved to express the characteristics of concrete under consideration (i.e. the proportion of concrete, the shape of the structure, relative humidity, etc.). And the predicted values from each design code under same environment differ from each other. To predict the characteristics of concrete, the long-term experiments of creep and shrinkage is necessary but this is not suitable for a construction field. In this study, adjustment method of creep coefficient using sensitivity analysis is proposed to predict creep coefficient of concrete exactly and it is checked up on the validity of the predicting method by comparing to the assumed value and predicted one.

• Journal of the International Relations & Interdisciplinary Education
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• v.1 no.1
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• pp.61-79
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• 2021

In order to implement an artificial intelligence lawyer, this study looked at how to structure legal principles, and then gave specific examples of how structured legal principles can be expressed in predicate logic. While previous studies suggested a method of introducing predicate logic for the reasoning engine of artificial intelligence lawyers, this study focused on the method of expressing legal principles with predicate logic based on the structural appearance of legal principles. Jurisprudence was limited to the content of articles and precedents, and the vertical hierarchy leading to 'law facts - legal requirements - legal effect' and the horizontal hierarchy leading to 'legal effect - defense - defense' were examined. In addition, legal facts were classified and explained that most of the legal facts can be usually expressed in unary or binary predicates. In future research, we plan to program the legal principle expressed in predicate logic and realize an inference engine for artificial intelligence lawyers.

• Fire Science and Engineering
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• v.26 no.6
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• pp.57-63
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• 2012

The modern trend for high-rise buildings makes the application of fire protection systems difficult and the current systems have a limitation to provide appropriate functions. Indoor hydrant systems are fire suppression systems installed in most buildings that require valves, hoses, and nozzles to be manually operated in the event of a fire. Therefore, high discharge pressure can cause difficulty in the operation of indoor fire hydrant systems and damage to hoses due to a high reaction force. To prevent these problems, the pressure is reduced and decompression valves are commonly installed at angle valves which are the discharge points of indoor hydrants. In the case of high-rise buildings, however, there are cases where stable operation is difficult even with the installation of decompression valves. To verify this, we have measured the decompression performance by the orifice diameter and calculated the reaction force. Results of the study showed that decompression valves need to be produced in different sizes to provide stable decompression where high pressure is required as in high-rise buildings.

• Journal of the Korea Organic Resources Recycling Association
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• v.4 no.1
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• pp.73-81
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• 1996

The expriment was carried out to clarify the fertilizer efficiency of a garbage-based compost in cultivation of leaf vegitables. 1. Only application of 8 tons per 10 of the compost did not have any growth injury to "Osaka-shirona" (a cultivar of Brassica pekinensis L.) in a pot experiment 2. In four continuous cropping with application of 3 tons per 10 a of the compost before every seeding, "Osaka-shirona" grew satisfactorily. 3. Osaka-shirona, spinich and garland chrysanthemum were cultivated under a plastic house applied with 2 tons per a of each of the garbage-based compost and cattle manure, delayed release fertilizer and bark compost on the market. There was no difference of the vegetable yields among the applied field, as well as of the contents of ${\beta}$-carotene, vitamin C, Ca and Fe.

• Aerospace Engineering and Technology
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• v.9 no.2
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• pp.44-50
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• 2010

COMS accommodates multiple payloads; Meteorological Image(MI), Ocean Color Imager(GOCI) and Ka-band communication payloads. In order to improve the quality of MI visible channel, the moon image has been taken into account as backup reference in addition to Albedo monitoring. However, obtaining the moon image by adding special mission schedule is not recommended after IOT, because we may miss chances to obtain meteorological images during the time slots for special imaging. As an alternative solution, an approach extracting moon image from MI FD(Full Disk) image has been proposed when the moon is positioned near to the earth. However, prediction of acquisition time of moon image is somewhat difficult as the moon moves while the MI is scanning type sensor. And the moon can not be seen when it is behind the earth or outside of FD field of view. This paper discusses how effectively the moon can be detected by the MI FD imaging. For that purpose, this paper describes an approach taken to predict the time when the moon image is achievable and then introduces the results obtained from computer simulation.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.11
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• pp.41-47
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• 2005

Even more than 240 commercial geostationary communication satellites currently on orbit at the higher location than the GPS orbit altitude perform their own missions only by the support of the ground segment because of weak visibility from GPS. In addition, the orbit determination accuracy is very low without using two or more dedicated ground tracking antennas in intercontinental ground segment, since the satellite hardly moves with respect to the ground station. In this paper, we propose the GSPS(Geostationary Satellite Positioning System) in circular orbits of two sidereal days period higher than the geosynchronous orbit for orbit determination and autonomous satellite operation. The GSPS is conceived as a ranging system in that unknown positions of a geostationary satellite can be acquired from the known positions of the GSPS satellites. Each GSPS satellite transmits navigation data, clock data, correction data, and geostationary satellite command to control a geostationary satellite.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.4
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• pp.53-60
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• 2004

Optimal design of the hybrid motor has been performed for the first stage of nanosat air launch vehicle using F-4E Phantom as mother plane. Selected design variables are number of ports, the initial oxidizer flux, the combustion chamber pressure, and the nozzle expansion ratio. GBM(Gradient Based Method) and GA(Genetic Algorithm) are simultaneously used to compare the versatility of each algorithm for optimal design in this problem. Also, two objective functions of motor weight, and length are treated separatedly in the optimization to study how the objective function can affect the optimal design. The design results show that the optimal design can be successfully achieved either using GBM or GA regardless of the choice of the objective function; motor weight or length. And nanosat air launch vehicle which has total mass of 704.74kg, and length of first stage 3.74m is designed.

• The Transactions of the Korea Information Processing Society
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• v.5 no.10
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• pp.2591-2599
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• 1998

In this paper, we proose a method of recognizing unknown words and correcting spelling errors(including spacing erors) to increase the performance of Korean information processing systems. Unknown words are recognized through comparative analysis of two or more morphologically similar eojeols(spacing units in Korean) including the same unknown word candidates. And spacing errors and spelling errors are corrected by using lexicatlized rules shich are automatically extracted from very large raw corpus. The extractionof the lexicalized rules is based on morphological and contextual similarities between error eojeols and their corection eojeols which are confirmed to be used in the corpus. The experimental result shows that our system can recognize unknown words in an accuracy of 98.9%, and can correct spacing errors and spelling errors in accuracies of 98.1% and 97.1%, respectively.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.1
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• pp.20-28
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• 2014

In this paper, based on the characteristics of proportional navigation, a composite guidance law is proposed for impact angle control of passive homing missiles maintaining the lock-on condition of the seeker. The proposed law is composed of two guidance commands: the first command is to keep the look angle constant after converging to the specific look angle of the seeker, and the second is to impact the target with terminal angle constraint and is implemented after satisfying the specific line of sight(LOS) angle. Because the proposed law considers the seeker's filed-of-view(FOV) and acceleration limits simultaneously and requires neither time-to-go estimation nor relative range information, it can be easily applied to passive homing missiles. The performance and characteristics of the proposed law are investigated through nonlinear simulations with various engagement conditions.

• Journal of Internet of Things and Convergence
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• v.2 no.4
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• pp.27-34
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• 2016

In this paper, we designed and implemented a system to easily check and manage book inventory using web and Android mobile device. In the previous conventional method, the user visits the bookstore directly and then checks the inventory. However, in this case, the user accessibility is inconvenient, and it is troublesome to check or reconfirm the inventory. In order to solve these inconveniences, we provide book inventory management system for requesting book purchase and inquiring bulletin board by book field, and then providing real time inventory check with book application and purchase functions. In addition, through the push notification function, we can catch up with the purchase status of the ordered books on the web and Android mobile device in real time. Therefore, we designed and implemented a function that enables bookstore operators and users to easily and conveniently manage by providing statistical information on inventory data.