• Journal of the Korean Crystal Growth and Crystal Technology
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• v.33 no.4
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• pp.125-131
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• 2023

Ga₂O₃ thin films were deposited on Ti substrates using metal organic chemical vapor deposition (MOCVD) at temperatures ranging from 350 to 500℃. Lower deposition temperatures were chosen to minimize thermal deformation of the Ti substrate and its impact on the Ga₂O₃ film. Film surfaces tended to become rough at temperatures below 500℃ due to three-dimensional growth, but the film formed at 500℃ had the most uniform surface. All deposited films were amorphous in structure. Vertical Schottky diodes were fabricated and I-V and C-V measurements were performed. I-V measurements showed higher operating voltages compared to a typical SBD for films grown at different temperatures. The sample grown at 500℃, which had the most uniform surface, exhibited the lowest operating voltage. Higher growth temperatures resulted in higher capacitance values according to C-V measurements.

• Journal of The Geomorphological Association of Korea
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• v.17 no.1
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• pp.59-72
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• 2010

This study is based on the observation on the patterned ground found in the northern part of the Baekdusan during two fieldtrips of 2008 summer. The patterned grounds are found in two areas-Dalmun and Socheonji. The patterned ground found around Dalmun are well-sorted, having fine materials in the center and coarse (boulder size) materials in the rim, and stretching in the form of stairs. Meanwhile, the types of patterned ground found around Socheonji are various, including polygon, stripe, and circular patterns. The particle size analysis and morphological analysis of comprising materials are carried out only for the patterned ground of Socheonji. The mean short and long axis of the patterned grounds are 91cm and 163cm, respectively. The distribution pattern of material size from the most samples increase toward the rim, indicating the patterned grounds are well-sorted. The comprising materials are dominated by silt, which is very susceptible for freeze-thaw cycle. The lower ratio of clay (low less than 10%), suggests that physical weathering is more dominant rather than chemical weathering. The involution structure found in the vertical section of the patterned grounds is likely to have formed by active cryoturbation which is one of the dominant geomorphic processes in the periglacial environments like the study area.

• Steel and Composite Structures
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• v.49 no.1
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• pp.81-89
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• 2023

A simplified calculation method of natural vibration characteristics of high-speed railway multi-span bridge-longitudinal ballastless track system is proposed. The rail, track slab, base slab, main beam, bearing, pier, cap and pile foundation are taken into account, and the multi-span longitudinal ballastless track-beam-bearing-pier-cap-pile foundation integrated model (MBTIM) is established. The energy equation of each component of the MBTIM based on Timoshenko beam theory is constructed. Using the improved Fourier series, and the Rayleigh-Ritz method and Hamilton principle are combined to obtain the extremum of the total energy function. The simplified calculation formula of the natural vibration frequency of the MBTIM under the influence of vertical and longitudinal vibration is derived and verified by numerical methods. The influence law of the natural vibration frequency of the MBTIM is analyzed considering and not considering the participation of each component of the MBTIM, the damage of the track interlayer component and the stiffness change of each layer component. The results show that the error between the calculation results of the formula and the numerical method in this paper is less than 3%, which verifies the correctness of the method in this paper. The high-order frequency of the MBTIM is significantly affected considering the track, bridge pier, pile soil and pile cap, while considering the influence of pile cap on the low-order and high-order frequency of the MBTIM is large. The influence of component damage such as void beneath slab, mortar debonding and fastener failure on each order frequency of the MBTIM is basically the same, and the influence of component damage less than 10m on the first fourteen order frequency of the MBTIM is small. The bending stiffness of track slab and rail has no obvious influence on the natural frequency of the MBTIM, and the bending stiffness of main beam has influence on the natural frequency of the MBTIM. The bending stiffness of pier and base slab only has obvious influence on the high-order frequency of the MBTIM. The natural vibration characteristics of the MBTIM play an important guiding role in the safety analysis of high-speed train running, the damage detection of track-bridge structure and the seismic design of railway bridge.

• Journal of the Korea institute for structural maintenance and inspection
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• v.28 no.2
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• pp.61-68
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• 2024

The majority of high-speed railway bridges along the domestic Gyeongbu and Honam lines feature a PSC-box type structure with a span length ranging from 35 to 40m, which typically exhibits a first bending natural frequency of approximately 4 to 5Hz. When KTX high-speed trains transverse these bridges at speeds ranging from 290 to 310km/h, the vibration induced by the trains approaches the first bending natural frequency of the bridge. Furthermore, with the upcoming operation of a EMU-320 high-speed train and the anticipated increase in the speeds of these high-speed trains, there is a need to analyze the dynamic response of high-speed railway bridges. For this, based on measured responses from actual railway bridges, a numerical model was constructed using a numerical model updating technique. The dynamic response of the updated numerical model exhibited a strong agreement with the measured response from the actual railway bridges. Subsequently, this updated model was utilized to analyze the dynamic response characteristics of the bridges when KTX and EMU-320 trains operate at increased speeds. The maximum vertical displacement and acceleration at the mid-span of the bridges were also compared to those specified in the railway design standard with the increasing speed of KTX and EMU-320.

• Journal of Korean Tunnelling and Underground Space Association
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• v.26 no.1
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• pp.1-17
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• 2024

Analyzing the tunnel excavation behavior and its effect on the surrounding ground involves large deformation behavior. Therefore, in order to properly simulate the tunnel excavation process and rigorously investigate the actual effect of excavation on surrounding ground and tunnel structure large deformation analysis method is required. In this study, two major numerical approaches capable of considering large deformations behavior were applied to investigate the effect of tunnel boring machine excavation on the surrounding ground: coupled Eulerian-Lagrangian (CEL) and the automatic remeshing (AR) method. Relative performance of both approaches was evaluated through the ground response due to TBM excavation. The ground response will be quantified by estimating the range of the excavation damaged zone (EDZ). By comparing the results, the range of the EDZ will be suggested on the vertical and horizontal direction along the TBM excavation surface. Based on the computed results, it was found that the size of EDZ around the excavation surface and the tendencies was in good agreement among the two approaches. Numerical results clearly show that the size of the EDZ around the tunnel tends to be larger for rock with higher RMR rating. The size of the EDZ is found to be direct proportional to the tunnel diameter, whereas the depth of the tunnel is inversely proportional due to higher confinement stress around the excavation surface.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.23 no.4
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• pp.110-126
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• 2024

Several studies have focused on developing the safest and most efficient path from the current location to the available parking area for vehicles entering a parking lot. In the present study, the parking lot structure and parking environment such as the lane width, width, and length of the parking space, were vaired by referring to the actual parking lot with vertical and horizontal parking. An automatic parking path planning model was proposed by collecting path data by various setting angles and environments such as a starting point and an arrival point, by putting the collected data into a deep learning model. The existing algorithm(Hybrid A-star, Reeds-Shepp Curve) and the deep learning model generate similar paths without colliding with obstacles. The distance and the consumption time were reduced by 0.59% and 0.61%, respectively, resulting in more efficient paths. The switching point could be decreased from 1.3 to 1.2 to reduce driver fatigue by maximizing straight and backward movement. Finally, the path generation time is reduced by 42.76%, enabling efficient and rapid path generation, which can be used to create a path plan for autonomous parking during autonomous driving in the future, and it is expected to be used to create a path for parking robots that move according to vehicle construction.

• The Journal of the Convergence on Culture Technology
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• v.10 no.5
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• pp.453-458
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• 2024

If you are unable to get comfortable sleep to maintain and recover your health, it will cause a lot of disruption to your daily life. Among the intraoral devices used to resolve snoring, obstructive sleep apnea, bruxism, teeth clenching, and mouth breathing, which interfere with a comfortable sleep, devices that stabilize the lower jaw by moving it forward are a treatment that replaces surgical therapy and positive airway pressure. It is showing effect. During use of the device, a force is generated that causes the lower jaw to return to its original position, so a device that fixes it with screws, rubber bands, etc. is used. To see the effect of the device, you must bite your upper and lower teeth. In order to eliminate the inconvenience of having to stay closed while sleeping, the device is manufactured only in the upper jaw and creates a vertical guideway in the lingual embarasure of the lower jaw in the shape of a key & key way structure, allowing twisting movements and allowing forward and lateral movements. It is about the development of a device that has a blocking function that allows the mouth to be opened while wearing the device and has a function that solves sleep apnea by inducing airway expansion during sleep.

• Journal of Korean Society of Forest Science
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• v.109 no.2
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• pp.115-123
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• 2020

The vertical distribution of vegetation can be classified according to the altitudinal gradient and the distribution of species along this gradient. The purpose of this study was to analyze the vegetation structure, species composition, dimensional density, and change according to altitude. These data illustrate the distribution of coniferous forest by altitude. By order of importance, the vegetation structure of this mixed forest consisted of Abies nephrolepis (12.2), Pinus koraiensis (10.86), and Acer komarovii (8.11). As a result of species composition according to the altitude, A. nephrolepis and Maianthemum bifolium increased in importance with increasing altitude. Tripterygium regelii emerged between 1,400 m and 1,600 m, which indicates that forest gaps were frequent at that elevation. The species diversity index was the highest from 1,400-1,500 m and coincided with the presence of forest gaps. The changes in A. nephrolepis of evergreen conifers increased significantly from 402 ± 5.4 ha.^-1 to 528 ± 11.6 ha.^-1 for two years, and decreased from 57 ± 1.3 ha.^-1 to 56 ± 1.6 ha.^-1 for P. koraiensis. The density of A. nephrolepis and P. koraiensis seedlings significantly increased at 1,500-1,600 m. The results of this study can be used as a basis to identify the mast seeding year with the increase or decrease of seedlings. In addition to documenting the evergreen conifer population of the Seorak Mountain, these results can be built upon for future monitoring of seedlings mortality.

• Economic and Environmental Geology
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• v.45 no.5
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• pp.513-523
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• 2012

The upper sedimentary layer of the Ulleung Basin in the East Sea shows stacked mass-flow deposits such as slide/slump deposits in the upper slope, debris-flow deposits in the middle and lower slope, and turbidites in the basin plain. Shallow gases or gas hydrates are also reported in many area of the Ulleung Basin, which are very important in terms of marine resources, environmental changes, and geohazard. This paper aims at studying acoustic characteristics and distribution pattern of gas-related structures such as acoustic column, enhanced reflector, dome structure, pockmark, and gas seepage in the upper sedimentary layer, by analysing high-resolution chirp profiles. Acoustic column shows a transparent pillar shape in the sedimentary layer and mainly occurs in the basin plain. Enhanced reflector is characterized by an increased amplitude and laterally extended to several tens up kilometers. Dome structure is characterized by an upward convex feature at the seabed, and mainly occurs in the lower slope. The pockmark shows a small crater-like feature and usually occurs in the middle and lower slope. Gas seepage is commonly found in the middle slope of the southern Ulleung Basin. These gas-related structures seem to be mainly caused by gas migration and escape in the sedimentary layer. The distribution pattern of the gas-related structures indicates that formation of these structures in the Ulleung Basin is controlled not only by sedimentary facies in upper sedimentary layer but also by gas-solubility changes depending on water depth. Especially, it is interpreted that the chaotic and discontinuous sedimentary structures of debris-flow deposits cause the facilitation of gas migration, whereas the continuous sedimentary layers of turbidites restrict the vertical migration of gases.

• Cartoon and Animation Studies
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• s.30
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• pp.169-199
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• 2013

In various directions of cartoon, vertical stroll direction is opposite to the page direction of existing published cartoon with the popularity of webtoon and established new genre. Lots of studies on published cartoon focus on the cut direction by page, but webtoon doesn't have any concept of page. The pivot of cartoon oriented people is changed from paper to computer monitor as times go by, characteristics of media are changed and media is gradually diversified. Like the strengthening of mobile caused by smart phone's popularity, tablet PC's propagation in public education, etc. cartoon is included to the environment of media which is rapidly changed. In this situation, one of cartoon's unchanged important identities can be the direction made by harmony between picture and text. This thesis analyzed symbolic characteristics and effective value of hyogwatae, mimetic words of cartoon, focusing on works of Heo, Young Man. Hyogwatae just delivers not only sound but also shape, feeling, status, etc. and has significant characteristics by invoking the imaginary structure of literature. Strengths of modern Korean, various linguistic expressions and syllabic systems, let people feel minute feeling of language and difference of emotion and remember the memory through the direct and indirect experiences, so it makes it nuance. Because of the characteristics, representative works of Heo, Young Man have commercialization and writer characteristics, have communicated with people for a long time and have plentiful knowledge of Korean cartoon. The characteristics of hyogwatae in Heo, Young Man's cartoon make a lot of effects for the expression and delivery of cartoon more than the general expectation. When conducting the study focusing on the symbolic process of language, uncertainty and vague standard of judgement caused by the wide factors of study on the direction of general cartoon could be endured. And, through the Heo, Young Man's deep analysis on hyogwatae's direction, readers enjoy the process while inferring actually and intellectually between pictures and sentences. In the process, the equipment stimulating imagination more than pictures, effects and dialogues is hyogwatae. It's reader's equipment of active participation and its strength is symbolic structure.