• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2023.05a
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• pp.151-151
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• 2023

An accurate prediction of the hydrodynamic maneuvering darivatives is essential to desing a robust control system of a UUV(unmanned underwater vehicle). Typically, these derivatives were estimated by either the towing tank experiment or semi-empirical methods. With the enhancement of high performance computing capacity, a numerical analysis using computational fluid dynamics has reach the level of experiment. Therefore, the aims of the present research are to numerically develop a computational model for the vertical planar motion mechanism of a UUV and to estimate the hydrodynamics loads in 6-DOF. The target structure of the present study was manta type UUV (12meter length). The numerical model was developed in 1/ 6 model scale. Numerical results were compared with the results of the towing tank experiment for validation. In the present study, a commercial RANS-based viscous solver STARCCM+ (ver 17.06) was used.

• Journal of IKEEE
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• v.27 no.4
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• pp.567-572
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• 2023

In this paper, the breakdown voltage of Pi-LDMOS (Partial isolation lateral double diffused metal oxide semiconductor) was analyzed by simulation. Breakdown voltage variation is investigated under various settings of Parial buied oxide(P-BOX) parameters(length, thickness, location) and their mechanism is specified. In addition, the change in on-resistance in the breakdown voltage and trade-off relationship was analyzed according to the change in the P-BOX parameter, and the Figure-of-merit(FOM) was calculated and compared. In proposed structure, Lbox=5 ㎛, tbox=2 ㎛, and Lbc=2 ㎛ showed the highest breakdown voltage of 138V, and Lbox=5 ㎛, tbox=1.6 ㎛, and Lbc=2 ㎛ showed the highest FOM. Compared to conventional LDMOS, the breakdown voltage is 123% and FOM is 3.89 times improved. Therefore, Pi-LDMOS has a high breakdown voltage and FOM, which can contribute to the improvement of the stable operating range of the Power IC.

• The Research Journal of the Costume Culture
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• v.31 no.6
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• pp.776-792
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• 2023

This study aims to analyze the traditional attire of four ethnic minority groups in Northeastern China: Daur, Ewenki, Oroqen, and Hezhen, considering their natural environment, lifestyles, and cultural influences. A literature review of academic papers, books, and online resources was conducted, along with indirect investigations through artifacts. The Daur people, being equestrian, have garments with deep slits, vibrant colors, and elaborate decorations. The Ewenki people wear clothes made of fabric in the summer and primarily deer skin in the winter, and their clothing is simple and not flashy. The Oroqen people's clothing typically has slits at the front, back, or on both sides, and they wear a waist belt. The Hezhen people, an ethnic group that primarily hunts and fishes, wear two-piece clothing with a hip-length top and pants or other fur-trimmed garments. All groups incorporate symbolic patterns influenced by Shamanism, along with animal headgear and leather shoes. We observed that the traditional costumes of ethnic minority groups in Northeastern China share many commonalities in form, but there are detailed differences in material, shape, color, and decoration due to unique geographical and climatic characteristics as well as differences in livelihood. Additionally, the structure of clothing varies depending on each tribe's shamanistic practices and lifestyle.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2023.04a
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• pp.63-63
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• 2023

Sugar beet (Beta vulgaris L.) is one of the most important sugar crops and provides up to 30% of the world's sugar production. In this study, we mainly performed RNA-sequencing to obtain identify putative genes involved in biosynthesis pathway of sucrose in sugar beet and comparative transcriptomic analyses in the four developmental stages (50, 90, 160 and 330 days after seedling). As a result of the sugar content analysis, it was increased significantly from 50 to 160 days after seedling (DAS), and then decreased at 330 DAS. On the other hand, the taproot weight, length, and width were increased during all the growth periods. Out of 21,451 genes with expressed value, 21,402 (99.77%) genes had functional descriptions. Among the three comparisons, S1 (50 DAS) vs. S2 (90 DAS), S1 vs. S3 (160 DAS), and S1 vs. S4 (330 DAS), expression profiling of the transcripts was identified 4,991 with differentially expressed genes (DEGs). By comparing the top 20 enriched gene ontology (GO) terms as three comparisons, the top GO terms were commonly confirmed with external encapsulating structure, cell wall, and extracellular regions. In addition, the 38 enriched candidate genes related to sucrose biosynthetic pathway were screened from the entire DEG pool, and the candidate genes might be providing a basic data for further sugar metabolism studies in development of sugar beet taproot.

• Steel and Composite Structures
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• v.48 no.1
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• pp.19-25
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• 2023

Due to high application of concrete structures in construction industry, however, the quality improvement is essential. One of the new ways for this purpose is adding the nanoparticles to the concrete. In this work, vibration analysis of concrete beams reinforced by graphene oxide (GO) nanoparticles based on mathematical model has been investigated. For the accuracy of the presented model, the experimental study is done for comparing the compressive strength. Since the nanoparticles can not be solved in water without any specific process, at the first, GO nanoparticles should be dispersed in water by using shaker, magnetic striker, ultrasonic devices and finally mechanical mixer. For modelling of the strucuture, sinusoidal shear deformation beam theory (SSDBT) is utilized. Mori-Tanak model model is utilized for obtaining the effective properties of the beam including agglomeration influences. Utilizing the energy method and Hamilton's principal, the motion equations are calculated. The frequency of the concrete beam is obtanied by analytical method. Three samples with 0.02% GO nanoparticles are built and its compressive strength is compared which shows a good accuracy with maximum 1.29% difference with mathematical model and other papers. The aim of this work from the theoretical study is investigating the effects of nanoparticles volume percentage and agglomeration, length and thickness of the beam on the frequency of the structure. The results show that the with enhancing the GO nanoparticles, the frequency is increased. For example, with enhancing the volume percent of GO nanoparticles from zero to 0.08%, the compressive strength is increased 48.91%. and 46.83%, respectively for two cases of with and without agglomeration.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.33 no.5
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• pp.191-195
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• 2023

Three-layer nano-coated films in applications for the back cover of mobile cellular phones were prepared utilizing a roll-to-roll continuous process. By introducing a coating layer with a ceramic/metal/ceramic three-layer structure, the inherent reflective properties of the metals were maintained while electrically insulating properties were maintained. The thickness of the composite coating layer on a large area PET film with a length of 1,500 nm and width of 500 nm was less than 60 nm, and a uniform thickness was maintained in all areas. The transmittance according to the wavelength range (240~1600 nm) of the nanocoating film gradually increases as the wavelength increases, and is about 48 % at 1,000 nm, which is within the infrared region, and about 35.5 % at 550 nm, which is within the visible region. These results meet the required level of coated backcover (< 40 %).

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.34 no.1
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• pp.16-21
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• 2024

Using electrochromic devices (ECD), smart window films that can change the colors from tinted state into transparent state by applying an external voltage were manufactured. Polyethylene terephthalate (PET) film was used as a substrate instead of conventional glass, and ECD modules having a total thickness of about 50 ㎛ were manufactured by sequentially introducing an ITO/Ag/ITO electrode layer, a WO3/TIC2 organic discoloration layer, and a Nafion fluorine electrolyte layer. Through a series of sputtering, bar coating, and thermal compression processes, a large scale smart window with a horizontal and vertical length of more than 80 mm was manufactured. When DC 3.5 V was applied, the transmittance decreased from 54 % to 24 % and moreover the color change could be confirmed even with the naked eye. Reversible color change capability at low external voltage implies that external sunlight can be selectively blocked which is effective in terms of energy saving.

• International Journal of Computer Science & Network Security
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• v.24 no.2
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• pp.53-58
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• 2024

This paper presents a novel miniaturized 3-D cubic antenna for use in wireless sensor network (WSN) application. The geometry of this antenna is designed as a cube including a meander dipole antenna. A truly omnidirectional pattern is produced by this antenna in both E-plane and H-plane, which allows for non-intermittent communication that is orientation independent. The operating frequency lies in the ISM band (centered in 2.45 GHz). The dimensions of this ultra-compact cubic antenna are 1.25*1.12*1cm3 which features a length dimension λ/11. The coefficient which presents the overall antenna structure is Ka=0.44. The cubic shape of the antenna is allowing for smart packaging, as sensor equipment may be easily integrated into the cube hallow interior. The major constraint of WSN is the energy consumption. The power consumption of radio communication unit is relatively high. So it is necessary to design an antenna which improves the energy efficiency. The parameters considered in this work are the resonant frequency, return loss, efficiency, bandwidth, radiation pattern, gain and the electromagnetic field of the proposed antenna. The specificity of this geometry is that its size is relatively small with an excellent gain and efficiency compared to previously structures (reported in the literature). All results of the simulations were performed by CST Microwave Studio simulation software and validated with HFSS. We used Advanced Design System (ADS) to validate the equivalent scheme of our conception. Input here the part of summary.

• The Journal of the Acoustical Society of Korea
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• v.28 no.4
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• pp.308-317
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• 2009

In the present work, a sensor system composed of an oscillator sensor and a Lamb wave sensor is proposed for the purpose of structural health monitoring. The oscillator sensing system detecting the shift of a structural resonant frequency in proportion to the amount of defects in the structure is a pretty sensitive and simple device, but its detectable range is limited to its local zone. The Lamb wave sensor system, however, is applicable to global detection of the defects. This study is aimed at investigating the feasible combination of the two systems to exploits their merits simultaneously. The scheme to use PZT patches as the oscillator sensor as well as the Lamb wave sensor was proposed to identify the position, length and number of cracks by means of TOF and amplitude of signals, and its validity was confirmed through experiments.

• Information Systems Review
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• v.25 no.2
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• pp.57-76
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• 2023

This study classifies the success of creators and YouTubers who have created channels on YouTube recently, which is the most influential digital platform. Based on the actual information disclosure of YouTubers who are in the field of science and technology category, video upload cycle, video length, number of selectable multilingual subtitles, and information from other social network channels that are being operated, the success of YouTubers using machine learning was classified and analyzed, which is the closest to the YouTube revenue structure. Our findings showed that neural network algorithm provided the best performance to predict the success or failure of YouTubers. In addition, our five factors contributed to improve the performance of the classification. This study has implications in suggesting various approaches to new individual entrepreneurs who want to start YouTube, influencers who are currently operating YouTube, and companies who want to utilize these digital platforms. We discuss the future direction of utilizing digital platforms.