• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.11a
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• pp.251-254
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• 2008

Ground firing test facility and test field for firing test of hybrid rocket engine were constructed. Ground firing test facility were composed of hybrid rocket engine, thrust stand, oxidizer storage/supply system, control system and data acquisition system. Firing tests of thrust 50 kgf class were conducted. Stable performance data was obtained and operational reliability of ground firing test facility were found.

• Current Optics and Photonics
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• v.2 no.6
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• pp.612-622
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• 2018

In wave-front-sensor-less adaptive optics (WFS-less AO) systems, the Jacopo Antonello (JA) method belongs to the model-based class and requires few iterations to achieve acceptable distortion correction. However, this method needs a lot of measurements, especially when it deals with moderate or severe aberration, which is undesired in free-space optical communication (FSOC). On the contrary, the stochastic parallel gradient descent (SPGD) algorithm only requires three time measurements in each iteration, and is widely applied in WFS-less AO systems, even though plenty of iterations are necessary. For better and faster compensation, we propose a WFS-less hybrid approach, borrowing from the JA method to compensate for low-order wave front and from the SPGD algorithm to compensate for residual low-order wave front and high-order wave front. The correction results for this proposed method are provided by simulations to show its superior performance, through comparison of both the Strehl ratio and the convergence speed of the WFS-less hybrid approach to those of the JA method and SPGD algorithm.

• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.3
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• pp.47-58
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• 2020

In this study, a thrust modulation through oxidizer mass flow rate control and internal ballistic analysis based on Whitmore and Chandlers' models was conducted on a blow-down hybrid rocket using nitrous oxide. The tank pressure prediction considering mass flow rate control of the self-pressuring oxidizer was conducted, and the results showed good agreements with experimental results. In order to verify the internal ballistic analysis, a ground combustion test using a 500 N class hybrid rocket was conducted, and it was confirmed that the experimental results and the analytical results were quite consistent in the chamber pressure and thrust, thereby, a modeling technique capable of predicting the thrust modulation performance is proposed.

• Journal of Plant Biotechnology
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• v.44 no.3
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• pp.208-219
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• 2017

Heterosis or hybrid vigor describes a phenomenon that superior phenotypes compared to the two parents are observed in the heterozygous $F_1$-hybrid plants. Identification and characterization of heterosis-related genes (HRGs) will facilitate hybrid breeding in crops. To identify HRGs in Brassica rapa, we analyzed transcriptome profiling using a Br300K microarray in non-heading Chinese cabbage at three developmental stages. A large number of genes were differentially expressed in $F_1$ hybrids and non-additive expression was prominent. Genes that are expressed specifically for $F_1$ hybrid at all three stages were Brassica-specific uncharacterized genes and several defense-related genes. Expression of several photosynthesis- and stress-related genes were also $F_1$ hybrid-specific. Thirteen NBS-LRR class genes showed high and specific expression in $F_1$ hybrid Shulu: some of them were characterized as defense genes in Arabidopsis, but most have not been. Further characterization of these defense-related genes in Brassica species and its application will be helpful for understanding the role of defense responses in heterosis. In addition, results obtained in this study will be valuable to develop molecular markers for heterosis and disease resistance in B. rapa.

• The Research Journal of the Costume Culture
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• v.20 no.3
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• pp.347-362
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• 2012

Formatively and artistically aspect, a hybrid can be said to be a phenomenon in which two mutually different genres are combined. Make-up is thought to be very important to arrange the foundation available for predicting and pursuing a flow and direction of future hybrid make-up based on this, by analyzing a flow centering on hybrid trend, which was shown previously. In terms of objectives of this study, the first, aim is to suggest a model for researching make-up by grasping the developmental process and the characteristics of hybrid art through considering an art theory of hybridity, shown in make-up. The second, aim is to design make-up by analyzing trends in make-up style after deconstructing the hybrid genre. The modern make-up design through genre-deconstruction characteristics beyond diverse plurality and genre could be known to be highlighted as aesthetic characteristic by a slight attempt as communication of open space, which connects culture and genre, which had failed to be recognized and was neglected. Empirical research has, produced a work by systematically arranging make-up design. This study, identifies two kind of barrier demolition, such as the class deconstruction and the temporal, spatial disorder centering on genre deconstruction of hybrid. There are infinite possibilities in developing make-up design in line with modern sensation through aesthetic element and symbolic significance through genre deconstruction. It was the expression mode in future make-up, to providing basic data, and to strengthening competitive edge of culture and art.

• International Journal of Aeronautical and Space Sciences
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• v.18 no.3
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• pp.512-521
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• 2017

This paper reports development process of a university-based sounding rocket using simplified hybrid rocket propulsion system for low-altitude flight application. A hybrid propulsion system was tried to be designed with as few components as possible for more economical, simpler and safer propulsion system, which is essential for the small scale sounding rocket operation as a CanSat carrier. Using blow-down feeding system and catalytic ignition as combustion starter, 250 N class hybrid rocket system was composed of three components: a composite tank, valves, and a thruster. With a composite tank filled with both hydrogen peroxide($H_2O_2$) as an oxidizer and nitrogen gas($N_2$) as a pressurant, the feeding pressure was operated in blowdown mode during thruster operation. The $MnO_2/Al_2O_3$ catalyst was fabricated for propellant decomposition, and ground test of propulsion system showed the almost theoretical temperature of decomposed $H_2O_2$ at the catalyst reactor, indicating sufficient catalyst efficiency for propellant decomposition. Auto-ignition of the high density polyethylene(HDPE) fuel grain successfully occurred by the decomposed $H_2O_2$ product without additional installation of any ignition devices. Performance test result was well matched with numerical internal ballistics conducted prior to the experimental propulsion system ground test. A sounding rocket using the developed hybrid rocket was designed, fabricated, flight simulated and launch tested. Six degree-of-freedom trajectory estimation code was developed and the comparison result between expected and experimental trajectory validated the accuracy of the developed trajectory estimation code. The fabricated sounding rocket was successfully launched showing the effectiveness of the simplified hybrid rocket propulsion system.

• Journal of the Korean Society for Marine Environment & Energy
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• v.18 no.2
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• pp.123-132
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• 2015

In this study, an arrangement design process for multiple wind turbines, placed on the 10MW class floating wave-offshore wind hybrid power generation system, was presented, and the aerodynamic performance was evaluated by using a computational fluid dynamics. An arrangement design, which produces a maximum power in the site wind field, was found by using a commercial program, WindPRO, based on a blade element momentum theory, then the effect of wake interference on the system between multiple wind turbines was studied and evaluated by using ANSYS CFX.

• The KIPS Transactions:PartB
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• v.11B no.2
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• pp.159-168
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• 2004

This paper presents hybrid classification method to improve the performance of satellite images classification by combining Bayesian maximum likelihood classifier, ISODATA clustering and fuzzy C-Means algorithm. In this paper, the training data of each class were generated by separating the spectral signature using ISODATA clustering. We can classify according to pixel's membership grade followed by cluster center of fuzzy C-Means algorithm as the mean value of training data for each class. Bayesian maximum likelihood classifier is performed with prior probability by result of fuzzy C-Means classification. The results shows that proposed method could improve performance of classification method and also perform classification with no concern about spectral signature of the training data. The proposed method Is applied to a Landsat TM satellite image for the verifying test.

• The Journal of Korean Academy of Prosthodontics
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• v.57 no.1
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• pp.24-30
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• 2019

The successful results of the treatment using a double crown denture have been reported in several papers for some of the few remaining teeth in patient. In particular, double crown dentures may be an alternative to treatment in cases where the periodontal status is poor and clasp type removable partial dentures are inappropriate (crown/root ratio > 1). In this case, the patient visited clinic with a chief complaint of difficulty in mastication due to loss of posterior teeth and overall teeth mobility. After teeth with severe periodontitis were extracted, treatment plan of mandible is Kennedy class I removable partial denture (RPD) and treatment plan of maxilla is hybrid telescopic double crown RPD with a friction pin. Patient is well adapted after the prosthetic treatment and we report due to achieving satisfactory results in pronunciation, mastication, retention and aesthetics.

• Proceedings of the Korean Society of Computer Information Conference
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• 2021.07a
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• pp.305-307
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• 2021

Alzheimer's Disease (AD) is a cognitive disorder characterized by memory impairment that can be assessed at early stages based on administering clinical tests. However, the AD pathophysiological mechanism is still poorly understood due to the difficulty of distinguishing different levels of AD severity, even using a variety of brain modalities. Therefore, in this study, we present a hybrid EEG-fNIRS modalities to compensate for each other's weaknesses with the help of Machine Learning (ML) techniques for classifying four subject groups, including healthy controls (HC) and three distinguishable groups of AD levels. A concurrent EEF-fNIRS setup was used to record the data from 41 subjects during Oddball and 1-back tasks. We employed both a traditional neural network (NN) and a CNN-LSTM hybrid model for fNIRS and EEG, respectively. The final prediction was then obtained by using majority voting of those models. Classification results indicated that the hybrid EEG-fNIRS feature set achieved a higher accuracy (71.4%) by combining their complementary properties, compared to using EEG (67.9%) or fNIRS alone (68.9%). These findings demonstrate the potential of an EEG-fNIRS hybridization technique coupled with ML-based approaches for further AD studies.