• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.63-64
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• 2012

A pyrotechnic actuated device (PAD) is a component that delivers high power in remote environments by combustion of a self-contained energy source. Historically, the design of these devices has been largely empirical and considered to be an art. In this study, an overview for developing an analytical model is introduced that efficiently evaluates performance of PAD. The model is integrated by three parts of different disciplines that are coupled in sequence with each other. First is the solid explosive burning to form product gas within an actuator and transport to an expansion chamber. Second is the insertion of initially tapered piston into a small hole by gas pressure in the chamber. Third is the shear cutting of the diaphragm from the piston to enable gas flow into the conduit. Some results of preliminary study for each of three parts are introduced in the presentation.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.2
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• pp.261-267
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• 2011

One of powerful software paradigms for distributed systems is a mobile agent system. Since the usage of mobile agent systems is increased, a software development model to construct softwares efficiently for these systems is needed. Currently, UML is a widely used software development model. However, existing UML can not describe the necessary mobility of the mobile agent based software systems in explicit way. In this paper, the interaction diagrams of UML(sequence diagrams and communication diagrams) are extended and used to express the mobility of the mobile agents including the functions of platforms of mobile agent systems in three ways. For a case study, we applied the extended diagrams to a distributed file searching using mobile agents, and we confirmed these diagrams can describe the function and mobility of mobile agents very well.

• The KIPS Transactions:PartB
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• v.17B no.6
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• pp.405-412
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• 2010

Previous background generation techniques showed bad performance in complex environments since they used only temporal contexts. To overcome this problem, in this paper, we propose a new background generation method which incorporates spatial as well as temporal contexts of the image. This enabled us to obtain 'clean' background image with no moving objects. In our proposed method, first we divided the sampled frame into m*n blocks in the video sequence and classified each block as either static or non-static. For blocks which are classified as non-static, we used MRF framework to model them in temporal and spatial contexts. MRF framework provides a convenient and consistent way of modeling context-dependent entities such as image pixels and correlated features. Experimental results show that our proposed method is more efficient than the traditional one.

• The Journal of the Acoustical Society of Korea
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• v.14 no.3
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• pp.61-70
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• 1995

In this paper, the PLP cepstrum which is close to human perceptual characteristics was extracted through the spread time area to get the temperal feature. Phonemes were recognized by artificial neural network similar to the learning method of human. The phoneme strings were matched by Markov models which well suited for sequence. Phoneme recognition for the continuous Korean speech had been done using speech blocks in which speech frames were gathered with unequal numbers. We parameterized the blocks using 7th order PLPs, PTP, zero crossing rate and energy, which neural network used as inputs. The 100 data composed of 10 Korean sentences which were taken from the speech two men pronounced five times for each sentence were used for the the recognition. As a result, maximum recognition rate of 94.4% was obtained. The sentence was recognized using Markov models generated by the phoneme strings recognized from earlier results the recognition for the 200 data which two men sounded 10 times for each sentence had been carried out. The sentence recognition rate of 92.5% was obtained.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.2
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• pp.426-434
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• 2010

This study is experimentally performed to evaluate the strength reduction behavior and its statistical properties of plain woven glass/epoxy composites. The results indicate that the major impact damage of plain woven glass/epoxy composites is the fiber breakage and matrix crack, whereas the dominant impact damage of unidirectional carbon/epoxy laminates is the delamination, which depends on the stacking sequence. The residual strength prediction models, previously proposed on unidirectional laminates, are applied to evaluate the residual strength of plain woven glass/epoxy composites with impact damage. Among these models, the results by Caprino and Avva's model have a good agreement with the experimental results. To investigate the variability of residual strength of the impacted composite materials, a statistical model was proposed and its results were in conformance with the experimental results regardless of their thickness.

• Journal of Korean Society for Geospatial Information Science
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• v.17 no.3
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• pp.49-56
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• 2009

Recently, a generation of high quality mosaic images from video sequences has been attempted by a variety of investigations. Among the matter of investigation, in this paper, generation on stereo mosaic utilizing airborne-video sequence images is focused upon. The stereo mosaic is made by creating left and right mosaic which are fabricated by front and rear slices having different viewing angle in consecutive video frames. For making the stereo mosaic, motion parameters which are able to define geometric relationship between consecutive video frames are determined. For determining motion parameters, affine model which is able to explain relative motion parameters is applied by this paper. The mosaicing method using relative motion parameters is called by free mosaic. The free mosaic proposed in this paper consists of 4 step processes: image registration with reference to first frame using affine model, front and rear slicing, stitching line definition and image mosaicing. As the result of experiment, the left and right mosaic image, anaglyphic image for stereo mosaic images are showed and analyzed y-parallax for checking accuracy.

• Proceedings of the KSRS Conference
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• 2009.03a
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• pp.97-100
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• 2009

The surface parameters associated with the land are usually dependent on the climate, and many physical processes that are displayed in the image sensed from the land then exhibit temporal variation with seasonal periodicity. An adaptive feedback system proposed in this study reconstructs a sequence of images remotely sensed from the land surface having the physical processes with seasonal periodicity. The harmonic model is used to track seasonal variation through time, and a Gibbs random field (GRF) is used to represent the spatial dependency of digital image processes. In this study, the Normalized Difference Vegetation Index (NDVI) was computed for one week composites of the Advanced Very High Resolution Radiometer (AVHRR) imagery over the Korean peninsula for 1996 and 2000 using a dynamic technique, and the adaptive reconstruction of harmonic model was then applied to the NDVI time series for tracking changes on the ground surface. The results show that the adaptive approach is potentially very effective for continuously monitoring changes on near-real time.

• 대한공업교육학회지
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• v.33 no.1
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• pp.249-264
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• 2008

In this dissertation, shallow $p^+-n$ junctions were formed by ion implantation and dual-step annealing processes and a new simulator is designed to model boron diffusion in silicon. This simulator predicts the boron distribution after ion implantation and annealing. The dopant implantation was performed into the crystalline substrates using $BF_2$ ions. The annealing was performed with a RTA(Rapid Thermal Annealing) and a FA(Furnace Annealing) process. The model which is used in this simulator takes into account nonequilibrium diffusion, reactions of point defects, and defect-dopant pairs considering their charge states, and the dopant inactivation by introducing a boron clustering reaction. FA+RTA annealing sequence exhibited better junction characteristics than RTA+FA thermal cycle from the viewpoint of sheet resistance and the simulator reproduced experimental data successfully. Therefore, proposed diffusion simulator and FA+RTA annealing method was able to applied to shallow junction formation for thermal budget. process.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.7
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• pp.903-909
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• 2021

Caenorhabditis elegans whose DNA sequence was completely identified is a representative species used in various research fields such as gene functional analysis and animal behavioral research. In the mean time, many researches on the bio-monitoring system to determine whether water is contaminated or not by using the swimming activities of nematodes. In this paper, we show the possibility of using the swimming activities of C. elegans in the development of a machine learning based bio-monitoring system which identifies chemicals that cause water pollution. To characterize swimming activities of nematode, BLS entropy is computed for the nematode in a frame. And, BLS entropy profile, an assembly of entropies, are classified into several patterns using clustering algorithms. Finally these patterns are used to construct data sets. We recorded images of swimming behavior of nematodes in the arenas in which formaldehyde, benzene and toluene were added at a concentration of 0.1 ppm, respectively, and evaluate the performance of the developed HMM.

• Composites Research
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• v.20 no.5
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• pp.1-6
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• 2007

This study was performed to make a comparison on low-velocity impact behavior between graphite/epoxy composite laminate and steel plate. In order to validate the proposed scheme fur the impact behavior of the plate, the Karas's impact model was used. The impact models for this comparative study are the graphite/epoxy composite plate having $[0/90/45/-45/-45/45/90/0]_{8S}$ laminate sequence and the steel plate with a steel ball impactor. The low-velocity impact behaviors for two types of plates were comparatively investigated and performed by considering different impactor velocities and weights respectively. In this investigation, it was found that the composite laminate has impact energy absorption effect due to more flexible behavior than the steel plate, and also it has better characteristics on impact damage and weight.