• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.4
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• pp.497-502
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• 2019

Metal oxide nanostructures are promising materials for advanced applications, such as high sensitive gas sensors, and high capacitance lithium-ion batteries. In this study, tin oxide (SnO) nanostructures were grown on a Si wafer substrate using a two-zone horizontal furnace system for a various substrate temperatures. The raw material of tin dioxide ($SnO_2$) powder was vaporized at $1070^{\circ}C$ in an alumina crucible. High purity Ar gas, as a carrier gas, was flown with a flow rate of 1000 standard cubic centimeters per minute. The SnO nanostructures were grown on a Si substrate at $350{\sim}450^{\circ}C$ under 545 Pa for 30 minutes. The surface morphology of the as-grown SnO nanostructures on Si substrate was characterized by field-emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM). Raman spectroscopy was used to confirm the phase of the as-grown SnO nanostructures. As the results, the as-grown tin oxide nanostructures exhibited a pure tin monoxide phase. As the substrate temperature was increased from $350^{\circ}C$ to $424^{\circ}C$, the thickness and grain size of the SnO nanostructures were increased. The SnO nanostructures grown at $450^{\circ}C$ exhibited complex polycrystalline structures, whereas the SnO nanostructures grown at $350^{\circ}C$ to $424^{\circ}C$ exhibited simple grain structures parallel to the substrate.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.1
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• pp.1-8
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• 2021

This study developed low-cost and high-efficiency pavement condition monitoring technology to produce the key information required for pavement management. A noise and artificial intelligence-based monitoring system was devised to compensate for the shortcomings of existing high-end equipment that relies on visual information and high-end sensors. From idea establishment to system development, functional definition, information flow, architecture design, and finally, on-site field evaluations were carried out. As a result, confidence in the high level of artificial intelligence evaluation was secured. In addition, hardware and software elements and well-organized guidelines on system utilization were developed. The on-site evaluation process confirmed that non-experts could easily and quickly investigate and visualized the data. The evaluation results could support the management works of road managers. Furthermore, it could improve the completeness of the technologies, such as prior discriminating techniques for external conditions that are not considered in AI learning, system simplification, and variable speed response techniques. This paper presents a new paradigm for pavement monitoring technology that has lasted since the 1960s.

• Ecology and Resilient Infrastructure
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• v.7 no.4
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• pp.308-319
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• 2020

In this study, the field applicability of the recently constructed multifunctional fishway in Seomunbo, Yeongcheon-si, and Gyeongsangbuk-do were examined. The analysis variables were R/C slab (S1) and R/C+S/C slab (S2), the underground passage standard areas (width × length) were 1.4 m × 0.2 m, 1.4 m × 0.3 m, and 1.4 m × 0.6 m, and the flow velocities were 0.8, 1.2, and 1.6 m/s. As a result of the analysis, the safety of the design of Seomunbo was evaluated. The analysis showed compared to the Seomoon Weir fishway, the maximum stress of S2 decreased by 24 - 32%, the bending moment of the underground passage decreased by 16 - 33%, the maximum stress of the sidewall decreased by 20 - 36%. In addition, the bending moment of the upper slab decreased by 17 - 33%, the maximum stress of the upper slab decreased by 9 - 28%, and the bending moment decreased by 19 - 33%. Complementation was required in the following percentages: 18% and 14% for the maximum stress and bending moment of the underground passage, respectively, 15% and 17% for the maximum sidewall stress and bending moment, respectively, and 11% and 16% for the upper slab maximum stress and bending moment, respectively. The results showed that S2 was superior to that of the Seomoon Weir fishway, and the underground passage size of 1.4 m × 0.3 m was superior to those of 1.4 m × 0.2 m and 1.4 m × 0.6 m, and R/C+S/C slab was superior to that of R/C slab. The findings are expected to be useful for constructing and designing the multifunctional fishway.

• Korean Journal of Construction Engineering and Management
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• v.22 no.2
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• pp.21-30
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• 2021

The existing construction industry is classified into industries with low productivity compared to other industries. In order to solve the decline in productivity in the construction industry, the world is focusing on off-site construction (OSC), which is about 40% more productive than existing construction methods. This high productivity is possible because the three stages of production, transport to the site, and site assembly are consistently maintained in a continuous flow. This study conducted a functional survey through literature review, preliminary field survey, questionnaire, and expert interview. The surveyed function were classified into five categories: convenience, flexibility, manageability, communication, and safety, and the functional characteristics of flexibility, manageability, and communication were high. Because of the change according to the construction progress, the production schedule of the factory, and the variety of transportation time required. Finally, A functional block diagram was developed based on the 15 functions corresponding with an average score of 4 or more in the surveyed function score result. If the OSC transport system is established through this study, It can contribute to a successful construction OSC project and increase productivity.

• Korean Journal of Construction Engineering and Management
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• v.22 no.1
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• pp.72-80
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• 2021

Based on the previous year's statistics, 37% of buildings in South Korea are aged over 30 years. As the number of the aging buildings increases, so does the need for maintenance. Building maintenance involves a significant number of works; the work of 'maintenance manager' accounting for the largest part. Currently, the maintenance history record is mostly in drawing or handwritten form which makes reviewing the data highly time consuming. Therefore, to improve the convenience of maintenance works and optimize historical data management, the existing maintenance process was analyzed. Problems were derived and a smart device-based automation model was established. In order to establish a smart device-based automation model, ① general flow of facility management process was analyzed and related articles were reviewed, ② current maintenance process was optimized, ③ functional block diagram of BIM Data, COBie Data, IoT, and AR-based automated maintenance management model was created, ④ a smart device-based automated maintenance management model was constructed, ⑤ finally, the above system was verified by testing the aforementioned model in the field site, evaluating the time required for the maintenance process and reviewing maintenance history data against the current one.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.2
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• pp.107-120
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• 2021

Electric-powered distributed propulsion aircraft possess a complex wake flow and mutual interference with the airframe, due to the use of many propellers. Accordingly, in the early design stage, rapid aerodynamic and load analysis considering the effect of propellers for various configurations and flight conditions are required. In this study, an efficient panel-based aerodynamic analysis method that can take into account the propeller effects is developed and validated. The induced velocity field in the region of propeller wake is calculated based on Actuator Disk Theory (ADT) and is considered as the boundary condition at the vehicle's surface in the three-dimensional steady source-doublet panel method. Analyses are carried out by selecting an isolated propeller of the Korea Aerospace Research Institute (KARI)'s Quad Tilt Propeller (QTP) aircraft and the propeller-wing configuration of the former experimental study as benchmark problems. Through comparisons with the results of computational fluid dynamics (CFD) based on actuator methods, the wake velocity of propeller and the changes in the aerodynamic load distribution of the wing due to the propeller operation are validated. The method is applied to the analysis of the Optional Piloted Personal Aerial Vehicle (OPPAV) and QTP, and the practicality and validity of the method are confirmed through comparison and analysis of the computational time and results with CFD.

• (The)Study of the Eastern Classic
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• no.32
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• pp.29-50
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• 2008

This thesis is an introduction and critique of the recently released 'Wongyo-Jinjeok(원교진적)'. 'Wongyo-Jinjeok' is the critique of Seokjeong Jeong-Jik Lee (석정 이정직, 1841-1910), a practical scientist and writer during the last years of the Korean Empire, on the calligraphy of Wongyo(원교) Gwang-Sa Lee (이광사, 1705-1777). Even though whether or not Seokjeong follows the flow of Donggukjinche(동국진체) is to be determined by the specialists in this field, this thesis is based on the view that Seokjeong was influenced by Donggukjinche. The academic value of 'Wongyo-Jinjeok' is Seokjeong's preface and epilogue which critiques Wongyo's writing. 'Wongyo-Jinjeok'is a collection of calligraphic specimens from the 18 pieces of Chinese poetry Wongyo had written before and after June 1756 which was the year after he was banished to Booryung. Seokjeong critiqued the writing of Wongyo from the perspective of calligraphic history in the preface and epilogue of 'Wongyo-Jinjeok'. Seokjeong had been positive about Wongyo's taking after the pre-Wangheejee calligraphic style. But at the same time, Seokjeong thought that Wongyo's ability to create was limited by the public morals of that time. Such thought of Seokjeong can be interpreted as an evaluation of Wongyo's calligraphy as having been externally stern but failing to transcend the realm of mastery to the realm of creation.

• 교육공학연구
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• v.33 no.1
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• pp.105-135
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• 2017

The purpose of this study is to clarify conceptually the difference of instructional coaching, instructional supervision, and instructional consulting by analyzing their own characteristics. The practices for instructional improvement are common in that fundamental objectives are improvement of instruction and development of teacher's professionalism in instruction. However, each area changed according to the social flow and the demands of the educational field and created a unique activity system. So, in order to get rid of this mixed use of these terms, it is meaningful to distinguish the concepts, attributes, and areas of each activity. The specific study questions were 1) what is the origin of coaching, supervision, and consulting? 2) how are instructional coaching, instructional supervision, and instructional consulting defined in existing research in korea? 3) how can we conceptually distinguish instructional coaching, instructional supervision, and instructional consulting? Based on reviewing various existing studies, First, this study investigated the conceptual origins and lexicons of coaching, supervision, and consulting, respectively, in addition reviewd the prior studies conducted in Korea with regard to instructional coaching, instructional supervision, and instructional consulting, and summarized how each concept is defined according to the researcher. Second, this study compared each two concept with another one. Finally, the existing definitions of instructional coaching, instructional supervision, and instructional consulting were analyzed to find out the inherent and common attributes of each concept. In conclusion, this study suggest that the concept of instructional consulting needs to be redefined to better reflect the characteristics of activities, and that studies that rethink the relationship between instructional coaching and instructional supervision are needed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.2
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• pp.33-39
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• 2021

As the interest and demand in the recycled yarn field has increased rapidly worldwide, domestic companies are also promoting research and development and business on recycled yarn. The chemical and thermal properties of four types of virgin and recycled PET samples from A and B company, which are the leading domestic companies in the recycled polyester yarn business, were confirmed through infrared (FT-IR) spectroscopy and differential scanning calorimetry (DSC). Virgin and recycled PET from two companies were compared. FT-IR spectroscopy revealed the typical spectra of PET for both companies and a different peak at 872 cm-1. DSC confirmed that the melting point and crystallization temperature of recycled PET were lower than those of virgin PET. These results indicate that small amounts of contaminants are an important parameter affecting the thermal properties of recycled PET. In the DSC results after seven repeats of the heating and cooling processes, all four samples showed that a lower melting point, crystallization temperature, and low heat flow intensity increased with increasing number of cycles. The results of melting and crystallization enthalpy also showed similar patterns.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.34 no.1
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• pp.25-33
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• 2021

With the development of machine learning techniques, various types of data such as vibration, temperature, and flow rate can be used to detect and diagnose abnormalities in machine conditions. In particular, in the field of the state monitoring of rotating machines, the fault diagnosis of machines using vibration data has long been carried out, and the methods are also very diverse. In this study, an experiment was conducted to collect vibration data from normal and abnormal compressors by installing accelerometers directly on rotary compressors used in household air conditioners. Data segmentation was performed to solve the data shortage problem, and the main features for the fault classification model were extracted through the chi-square test after statistical and physical features were extracted from the vibration data in the time domain. The support vector machine (SVM) model was developed to classify the normal or abnormal conditions of compressors and improve the classification accuracy through the hyperparameter optimization of the SVM.