• Smart Structures and Systems
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• 제29권4호
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• pp.625-640
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• 2022

Maglev rail joints are vital components serving as connections between the adjacent F-type rail sections in maglev guideway. Damage to maglev rail joints such as bolt looseness may result in rough suspension gap fluctuation, failure of suspension control, and even sudden clash between the electromagnets and F-type rail. The condition monitoring of maglev rail joints is therefore highly desirable to maintain safe operation of maglev. In this connection, an online damage detection approach based on three-dimensional (3D) convolutional neural network (CNN) and time-frequency characterization is developed for simultaneous detection of multiple damage of maglev rail joints in this paper. The training and testing data used for condition evaluation of maglev rail joints consist of two months of acceleration recordings, which were acquired in-situ from different rail joints by an integrated online monitoring system during a maglev train running on a test line. Short-time Fourier transform (STFT) method is applied to transform the raw monitoring data into time-frequency spectrograms (TFS). Three CNN architectures, i.e., small-sized CNN (S-CNN), middle-sized CNN (M-CNN), and large-sized CNN (L-CNN), are configured for trial calculation and the M-CNN model with excellent prediction accuracy and high computational efficiency is finally optioned for multiple damage detection of maglev rail joints. Results show that the rail joints in three different conditions (bolt-looseness-caused rail step, misalignment-caused lateral dislocation, and normal condition) are successfully identified by the proposed approach, even when using data collected from rail joints from which no data were used in the CNN training. The capability of the proposed method is further examined by using the data collected after the loosed bolts have been replaced. In addition, by comparison with the results of CNN using frequency spectrum and traditional neural network using TFS, the proposed TFS-CNN framework is proven more accurate and robust for multiple damage detection of maglev rail joints.

• 산업융합연구
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• 제20권8호
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• pp.127-136
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• 2022

본 연구는 코로나19 상황에서 우리나라 국민이 경험한 팬데믹의 개인정서와 사회변화 인식이 엔데믹 이후 재난대처 인식에 미치는 영향을 실증적으로 분석하기 위해 다중회귀모형을 활용하여 수행하였다. 이 연구를 위해 한국언론 진흥재단에서 실시한 「코로나19 이후 국민의 일상 변화 조사」를 사용하였고, 996명(남 508명, 여 488명)을 연구대상으로 설계하였다. 연구 결과, 코로나19 긍정정서와 사회변화 인식 요인들은 재난대처 인식에 정(+)의 영향을 미쳤으며, 공동체의식은 재난대처 인식에 부(-)의 영향을 미치는 코로나19 부정정서를 완화시켜 주는 조절효과가 있었다. 엔데믹 이후 재난대처 인식에 상대적으로 가장 많은 영향을 미치는 요인은 재난 상황시 우리나라 사회에 대한 자긍심과 안정감을 갖는 코로나19 긍정정서와 공동체의식이었다. 따라서 본 연구는 엔데믹 이후 재난 발생 상황에서 수행되는 정부의 선행 및 후속 조치 방안들이 국민에게 자긍심과 안정감을 주는 체계적인 재난대처 메뉴얼과 컨트롤 타워가 더 강력하게 요청되며, 국민에게는 재난 상황에서 개인적인 행동과 판단으로 대처하기보다는 재난을 함께 극복하려는 공동체의식이 요청됨을 시사한다.

• Earthquakes and Structures
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• 제23권5호
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• pp.445-462
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• 2022

To investigate and evaluate the seismic damage behaviors of steel reinforced recycled concrete (SRRC) filled circular steel tube composite columns, in this study, the cyclic loading tests of 11 composite columns was carried out by using the load-displacement joint control method. The seismic damage process, hysteretic curves and performance indexes of composite columns were observed and obtained. The effects of replacement rates of recycled coarse aggregate (RCA), diameter thickness ratio, axial compression ratio, profile steel ratio and section form of profile steel on the seismic damage behaviors of composite columns were also analyzed in detail. The results show that the failure model of columns is a typical bending failure under the combined action of horizontal loads and vertical loads, and the columns have good energy dissipation capacity and ductility. In addition, the replacement rates of RCA have a certain adverse effect on the seismic bearing capacity, energy consumption and ductility of columns. The seismic damage characteristics of composite columns are revealed according to the failure modes and hysteretic curves. A modified Park-Ang seismic damage model based on the maximum displacement and cumulative energy consumption was proposed, which can consider the adverse effect of RAC on the seismic damage of columns. On this basis, the performance levels of composite columns are divided into five categories, The interlayer displacement angle and damage index are used as the damage quantitative indicators of composite columns, and the displacement angle limits of composite columns at different performance levels under 80% assurance rate are calculated as 1/105, 1/85, 1/65, 1/28, and 1/25 respectively. On this basis, the damage index limits corresponding to each performance level are calculated as 0.045, 0.1, 0.48, 0.8, and 1.0 respectively. Finally, the corresponding relations among the performance levels, damage degrees, interlayer displacement angles and damage indexes of composite columns are established. The conclusions can provide reference for the seismic design of SRRC filled circular steel tube composite columns, it fills the vacancy in the research on seismic damage of steel reinforced recycled concrete (SRRC) filled circular steel tube composite columns.

• Geomechanics and Engineering
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• 제35권1호
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• pp.29-39
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• 2023

As the intensity of urban underground space development increases, more and more tunnels are planned and constructed, and sometimes it is inevitable to encounter situations where tunnels have to underpass the river embankments. Most previous studies involved tunnels passing river embankments perpendicularly or with large intersection angle. In this study, a project case where two EPB shield tunnels with 8.82 m diameter run parallelly underneath a river embankment was reported. The parallel length is 380 m and tunnel were mainly buried in the moderate / slightly weathered clastic rock layer. The field monitoring result was presented and discussed. Three-dimensional back-analysis were then carried out to gain a better understanding the interaction mechanisms between shield tunnel and embankment and further to predict the ultimate settlement of embankment due to twin-tunnel excavation. Parametrical studies considering effect of tunnel face pressure, tail grouting pressure and volume loss were also conducted. The measured embankment settlement after the single tunnel excavation was 4.53 mm ~ 7.43 mm. Neither new crack on the pavement or cavity under the roadbed was observed. It is found that the more degree of weathering of the rock around the tunnel, the greater the embankment settlement and wider the settlement trough. Besides, the latter tunnel excavation might cause larger deformation than the former tunnel excavation if the mobilized plastic zone overlapped. With given geometry and stratigraphic condition in this study, the safety or serviceability of the river embankment would hardly be affected since the ultimate settlement of the embankment after the twin-tunnel excavation is within the allowable limit. Reasonable tunnel face pressure and tail grouting pressure can to some extent suppress the settlement of the embankment. The recommended tunnel face pressure and tail grouting pressure are 300 kPa and 550 kPa in this study, respectively. However, the volume loss plays the crucial role in the tunnel-embankment interaction. Controlling and compensating the tunneling induced volume loss is the most effective measure for river embankment protection. Additionally, reinforcing the embankment with cement mixing pile in advance is an alternative option in case the predicted settlement exceeds allowable limit.

• 한일민족문제연구
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• 제21호
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• pp.1-43
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• 2011

This article introduces Abe Mituie's activities related to Korean and Japanese Buddhism and two newly discovered materials. He worked as a brain of Japanese cultural rule over Joseon Korea while holding various positions such as the president of KyeongSung Il Bo, the vice president of Kokmin Newspaper and the director of Central Joseon Association. Abe was responsible for Enkak Temple, the head temple of Japanese Rinzai section, and was one of the layman followers of Syak Soen who worked for the spread of modern Japanese Buddhism to Europe and America. He was a respectful Buddhist layman so as to teach Zen Buddhism for young Buddhist monks in Japan. After he started to assume charge in the Kyeong Sung Il Bo, he was also very active in movements in relation to Joseon Buddhism to the extent that he was found to be deeply involved in Joseon Buddhism sections. On the other hand, he concluded Joseon culture to be 'devastated.' He asserted that it was necessary to develop spiritual culture and revive Buddhism in order to resolve the devastation in the Joseon. In addition, he thought that Joseon Buddhism was ruined due to the misgovernment of the Joseon Dynasty, but had its own as great tradition as Japanese Buddhism. Therefore, in his opinion, there was a need to do research on Joseon Buddhism and find some way out of the contemporary difficulties. In order to save the situation, he made efforts to protect and revive Joseon Buddhism while paying continuous visits to Joseon Buddhist temples, supporting the publication of Buddhist canons and proposing to have a regular meeting of 'The Invitation of 30 Head Temples.' From his visit to Youngju Temple and his consistent relationship with Kang Daeryeon, it can be assumed that he was involved in reorganizing power structure in Joseon Buddhism and establishing various institutions. He emphasized the strict adherence of individuals and communities to rules in his lecture for students at Jung Ang Hak Rim. It was a way to revive Joseon Buddhism by creating a new social image of Joseon Buddhism. He continued to work for the restoration of Joseon Buddhism even after he retired from Kyeong Sung Il Bo and returned to Japan. He introduced the originality of Joseon Buddhism history to Japan and sent Japanese monks to Korea in order to do research and contribute to exchange between Korean and Japanese Buddhism. All things taken together, it is evident that Abe Mitzihe regarded Joseon as backward or stagnant from a perspective of evolutionist or orientalist, and was a Japanese elite to believe that it was just for Japan to control Korea. However, he was different from other Japanese elites in that he did not considered Joseon Buddhism merely as the object of propagation. He thought that Joseon Buddhism possessed its own great tradition and culture, but was ruined because of the misadministration of the Joseon Royal House. Therefore, in his opinion, Joseon Buddhism should be recovered by means of some supports, and its revival would lead to the restoration of Joseon culture as a whole, which would be realized by Japanese rule over Korea and Japanese elites' generous assistance.

• Geomechanics and Engineering
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• 제32권1호
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• pp.111-123
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• 2023

The slope of an open cut tunnel is located above the exit of the Leijia tunnel on the Changgan high-speed railway. During the excavation of the open cut tunnel foundation pit, the slope slipped twice, a large landslide of 92500 m³ formed. The landslide body and unstable slope body not only caused the foundation pit of the open cut tunnel to be buried and the anchor piles to be damaged but also directly threatened the operational safety of the later high-speed railway. Therefore, to study the stability change in the slope of the open cut tunnel under heavy rain and excavation conditions, a 3D numerical calculation model of the slope is carried out by Midas GTS software, the deformation mechanism is analyzed, anti-sliding measures are proposed, and the effectiveness of the anti-sliding measures is analyzed according to the field monitoring results. The results show that when rainfall occurs, rainwater collects in the open cut tunnel area, resulting in a transient saturation zone on the slope on the right side of the open cut tunnel, which reduces the shear strength of the slope soil; the excavation at the slope toe reduces the anti-sliding capacity of the slope toe. Under the combined action of excavation and rainfall, when the soil above the top of the anchor pile is excavated, two potential sliding surfaces are bounded by the top of the excavation area, and the shear outlet is located at the top of the anchor pile. After the excavation of the open cut tunnel, the potential sliding surface is mainly concentrated at the lower part of the downhill area, and the shear outlet moves down to the bottom of the open cut tunnel. Based on the deformation characteristics and the failure mechanism of the landslides, comprehensive control measures, including interim emergency mitigation measures and long-term mitigation measures, are proposed. The field monitoring results further verify the accuracy of the anti-sliding mechanism analysis and the effectiveness of anti-sliding measures.

• Steel and Composite Structures
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• 제47권1호
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• pp.91-102
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• 2023

To study the evaluation standard and control limit of mortar filling layer void length, in this paper, the train sub-model was developed by MATLAB and the track-bridge sub-model considering the mortar filling layer void was established by ANSYS. The two sub-models were assembled into a train-track-bridge coupling dynamic model through the wheel-rail contact relationship, and the validity was corroborated by the coupling dynamic model with the literature model. Considering the randomness of fastening stiffness, mortar elastic modulus, length of mortar filling layer void, and pier settlement, the test points were designed by the Box-Behnken method based on Design-Expert software. The coupled dynamic model was calculated, and the support vector regression (SVR) nonlinear mapping model of the wheel-rail system was established. The learning, prediction, and verification were carried out. Finally, the reliable probability of the amplification coefficient distribution of the response index of the train and structure in different ranges was obtained based on the SVR nonlinear mapping model and Latin hypercube sampling method. The limit of the length of the mortar filling layer void was, thus, obtained. The results show that the SVR nonlinear mapping model developed in this paper has a high fitting accuracy of 0.993, and the computational efficiency is significantly improved by 99.86%. It can be used to calculate the dynamic response of the wheel-rail system. The length of the mortar filling layer void significantly affects the wheel-rail vertical force, wheel weight load reduction ratio, rail vertical displacement, and track plate vertical displacement. The dynamic response of the track structure has a more significant effect on the limit value of the length of the mortar filling layer void than the dynamic response of the vehicle, and the rail vertical displacement is the most obvious. At 250 km/h - 350 km/h train running speed, the limit values of grade I, II, and III of the lengths of the mortar filling layer void are 3.932 m, 4.337 m, and 4.766 m, respectively. The results can provide some reference for the long-term service performance reliability of the ballastless track-bridge system of HRS.

• 한국프랜차이즈경영연구
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• 제2권2호
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• pp.70-83
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• 2011

농산물 수입개방에 따른 국제화에 대응하여 농사눌의 경쟁력 향상을 위한 농업의 구조조정의 필요성과 농산물 유통에 있어 농산물 제값받기, 공정거래, 능률 향상 등의 시대저 요청에 정부의 적절한 대응이 있어야만 한다. 이를 위해 공산물에 비해 보잡한 농산물의 유통구조를 효율적으로 변화시키고, 산지수집 단계에서부터 농산물 출하선택의 폭을 넓혀 안정적인 상품공급과 계획적인 생산체계를 유도하고 농산물의 원활한 수급조절과 판매 처리 능력을 확대하여야 한다. 또한, 유통과정에서 각종 부도덕한 상거래 행위를 근절시켜 유통정책의 효율적인 수립 및 집행을 위해 정확한 유통통계와 정보화가 필요하다. 농산물 유통구조 개선의 궁극적인 목적은 생산자에게는 상푸의 적정가격 보장과 생산의 극대화를 위한 시설개선이며, 소비자에게는 기호에 따라 적정가격의 최상푸질을 제공받는 것이다. 그러므로 경영의 효율성을 높여 단순히 유통비용 또는 마진을 낮추는 개선이 아닌 실제적인 구조조정을 통해 유통구조의 비용을 절감하여 최상의 생산품을 제공하여야만 향후 우리나라 농산물의 입지를 강화하고 소비자의 구매 욕구를 충족시킬 수 있을 것이다.

• 한국엔터테인먼트산업학회논문지
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• 제13권7호
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• pp.409-417
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• 2019

최근 영어 조기교육의 중요성이 증대되면서 미취학 아동들을 위한 많은 교육기관들에서 영어교육이 점차 활성화되고 있다. 특히 역할연기(Role-play)는 미취학 아동들의 언어에 대한 관심을 증진시키고 자연스럽게 영어권 문화를 접할 수 있어 아동들의 영어학습에서 효과적인 것으로 알려져 있다. 이에 따라 본 논문에서는 미취학 아동들을 대상으로 영어교육을 위한 역할연기에서 UCC의 효과적인 활용방법을 알아보도록 하였다. 먼저 연구를 위해 미취학 아동들에 대하여 사전, 사후 검사를 위한 설문을 진행하였다. 그리고 이를 SPSS로 분석하여 아동들의 UCC에 대한 이해, 영어에 대한 흥미, 역할연기에 대한 흥미, 연기에 대한 관심 등 알아보았다. 분석 결과, 대부분의 아동들은 UCC를 잘 알고 있었으며 시청이나 제작에 관한 흥미도 강함을 알 수 있었다. 제작된 콘텐츠 시청과 교사의 피드백을 통해 더 발전된 영어와 연기를 보이고 싶어 하였다. 따라서 미취학 아동의 영어교육에서도 교사의 통제하에 역할연기를 통해 UCC를 제작하고 활용하는 것으로써 언어와 연기의 발전을 보일 수 있으며 유튜브 등을 통해 콘텐츠를 배포함으로써 이에 대한 흥미를 더욱 높일 수 있을 것으로 사료된다. 이러한 연구의 결과는 어린이집이나 유치원에서 역할연기를 통한 영어 교육을 계획할 때 효과적으로 활용될 수 있을 것으로 기대한다.

• Advances in nano research
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• 제13권5호
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• pp.417-426
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• 2022

Bisphenol A (BPA) is one of the chemicals used in monomer epoxy resins and polycarbonate plastics. The surface-enhanced Raman spectroscopy (SERS) method is precise for identifying biological materials and chemicals at considerably low concentrations. In the present article, the substrates coated with gold nanoparticles have been studied to identify BPA and control the diseases caused by this chemical. Gold nanoparticles were made by a simple chemical method and by applying gold salt and trisodium citrate dihydrate reductant and were coated on glass substrates by a spin-coat approach. Finally, using these SERS substrates as plasmonic sensors and Raman spectroscopy, the Raman signal enhancement of molecular vibrations of BPA was investigated. Then, the molecular vibrations of BPA in some consumer goods were identified by applying SERS substrates as plasmonic sensors and Raman spectroscopy. The fabricated gold nanoparticles are spherical and quasi-spherical nanoparticles that confirm the formation of gold nanoparticles by observing the plasmon resonance peak at 517 nm. Active SERS substrates have been coated with nanoparticles, which improve the Raman signal. The enhancement of the Raman signal is due to the resonance of the surface plasmons of the nanoparticles. Active SERS substrates, gold nanoparticles deposited on a glass substrate, were fabricated for the detection of BPA; a detection limit of 10-9 M and a relative standard deviation (RSD) equal to 4.17% were obtained for ten repeated measurements in the concentration of 10-9 M. Hence, the Raman results indicate that the active SERS substrates, gold nanoparticles for the detection of BPA along with the developed methods, show promising results for SERS-based studies and can lead to the development of microsensors. In Raman spectroscopy, SERS active substrate coated with gold nanoparticles are of interest, which is larger than gold particles due to the resonance of the surface plasmons of gold nanoparticles and the scattering of light from gold particles since the Raman signal amplifies the molecular vibrations of BPA. By decreasing the concentration of BPA deposited on the active SERS substrates, the Raman signal is also weakened due to the reduction of molecular vibrations. By increasing the surface roughness of the active SERS substrates, the Raman signal can be enhanced due to increased light scattering from rough centers, which are the same as the larger particles created throughout the deposition by the spin-coat method, and as a result, they enhance the signal by increasing the scattering of light. Then, the molecular vibrations of BPA were identified in some consumer goods by SERS substrates as plasmonic sensors and Raman spectroscopy.