• Journal of the Korean Geosynthetics Society
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• v.17 no.4
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• pp.53-64
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• 2018

In this study, the evaluation to probability of failure for risk assessment of port structures on DCM reinforced soils, where stability and risk assessment are increasing in importance, was performed. As a random variables affecting the risk of DCM improved ground, the design strength, superposition (overlap) of construction, strength of the natural ground, internal friction angle and unit weight of the modified ground were selected and applied to the risk assessment. In addition, the failure probability for the entire system under ordinary conditions and under earthquake conditions were analyzed. As a result, it was found that the highest coefficient of variation in the random variable for the risk assessment of the DCM improved ground is the design strength, but this does not have a great influence on the safety factor, ie, the risk of the system. The main risk factor for the failure probability of the system for the DCM reinforced soils was evaluated as horizontal sliding in case of external stability and compression failure in case of internal stability both at ordinary condition and earthquake condition. In addition, the failure probability for ordinary horizontal sliding is higher than that for earthquake failure, and the failure probability for ordinary compression failure is lower than that for earthquake failure. The ordinary failure probability of the entire system is similar to the failure probability on earthquake condition, but in this case, the risk of earthquake is somewhat higher.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.3
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• pp.638-644
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• 2019

In this study, the fluid flow and heat transfer characteristics within sandwich panels are investigated using computational fluid dynamics. Within the sandwich panels having periodic cellular cores, air can freely move inside the core section so that the structure is able to perform multi-functional roles such as simultaneous load bearing and heat dissipation. Thus, there needs to examine the thermal and flow analysis with respect to design variables and various conditions. In this regard, ANSYS Fluent was utilized to explore the flow and heat transfer within the pyramidal truss sandwich structures by varying the truss angle and inlet velocity. Without the entry effect in the first unitcell, the constant rate of pressure and the constant rate of Nusselt number was observed. As a result, it was demonstrated that Nusselt number increases and friction factor decreases as the inlet velocity increases. Moreover, the rate of Nusselt number and friction factor was appreciable in the range of V=1-5m/s due to the transition from laminar to turbulent flow. Regarding the effect of design variable, the variation of truss angle did not significantly influence the characteristics.

• Journal of agriculture & life science
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• v.52 no.6
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• pp.103-109
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• 2018

The performance of drip irrigation devices depends on flow uniformity related to the function of pressure compensation. The flow uniformity can be secured when the internal fluid pressures at the positions of the flow holes are maintained uniformly. The pressure compensation effect of the drip irrigation devices can be optimized with the combination of soft silicon and labyrinth structures. However, for a drip irrigation devices composed of only hard labyrinth structures, the flow rate is changed largely with the length and the internal geometry of the labyrinth structure. Although a drip irrigation devices with only hard labyrinth structures can be fabricated simply, the changes of flow rates with internal fluid pressures are much larger than those of the drip irrigation devices with soft silicon. Because the drip irrigation devices with only labyrinth structures can be utilized widely through the optimization of the fluid pressure, the length of the structures, and the cross-sectional area of them, the study on the optimization can play an important role for enhancing the performance of the drip irrigation devices. In this study, experimental and numerical studies for investigating the performance of the drip irrigation devices had been conducted. In the experiments and numerical calculations(CFD), the variable parameters were the lengths of the labyrinth structures(#1~#8) and the fluid pressures(0.5~3.0 bar).

• Korean Journal of Optics and Photonics
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• v.29 no.6
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• pp.275-284
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• 2018

In this study we propose a hybrid color-filter design method in which a nanohole array and a nanodisk array are separated by nanopillars of the material AZ 1500. We propose a design method for an RGB color filter, using the tendency of transmitted light according to each design variable. Especially we analyzed the intensity distribution of the electric field in the cross section, and set the height of the nanopillars so that the local surface-plasmon resonances generated in the two different arrays do not affect each other. The optical characteristics of the optimized color filter are as follows: In the case of the red filter, the ratio of the wavelength band expressing red in the visible broadband is 55.01%, and the maximum transmittance is 41.53%. In the case of the green filter, the ratio of the wavelength band expressing green is 40.20%, and the maximum transmittance is 42.41%. In the case of the blue filter, the ratio of the wavelength band expressing blue is 32.78%, and the maximum transmittance is 30.27%. We expect to improve the characteristics of color filters integrated in industrial devices by this study.

• Journal of Technology Innovation
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• v.27 no.2
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• pp.99-122
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• 2019

ODA (Official Development Assistance) aims for practicing international humanitarianism in developing countries. However, ODA donors also seek to find convincing evidence meeting the national economic & political interests in the international community. In this regards, precise & unbiased estimation of the policy effects of ODA aid on the donors' exports to the recipient countries has recently become one of the primary concerns of the ODA donors, especially developing countries including Korea of which economy structure heavily relies on exports for economic growth. Based on the basic gravity model, this study empirically analyzes the effects of technical cooperation ODA delivering skills, knowledge and technical know-how on Korea's exports to the ODA recipient countries using 10-year panel data from 2007 to 2016. Specifically, by incorporating major variables affecting trade such as GDP, distance, FDI etc, the effect of technical cooperation ODA on Korea's exports to the ODA recipient countries is estimated with various kinds of panel models. As a result, technical cooperation ODA has a statistically significant impact on Korea's exports to ODA recipient countries, especially in the exports of intermediate goods. And the detail process of this black-boxed mechanism is scrutinized through case studies on Uzbekistan, The Philippines, and Morocco.

• Journal of the Korean GEO-environmental Society
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• v.12 no.5
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• pp.59-63
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• 2011

Ground dynamic parameter such as shear elastic modulus and damping ratio is a very important variable in design of ground-structure with repeated load and dynamic load. Shear elastic modulus and damping ratio on small strain below linear limit strain is constant regardless of strain. Shear elastic modulus as the maximum shear elastic modulus and damping ratio as the minimum damping ratio were considered. As a lot of experiment related to the maximum shear elastic modulus, which is in dynamic deformation characteristics, have been conducted, many factors including voiding ratio, over consolidation ratio(OCR), confining pressure, geology time, PI, and the number of load cycle affect to dynamic soil characteristic. However, the research of ground dynamic characteristic improved with grout is absent such as underground continuous wall construction, deep mixing method, umbrella arch method. In order to investigate the dynamic soil characteristics improved with grout, in this study, resonant column tests were performed with changing water content(20%, 25%, 30%) and injection ratio of grout(5%, 10%, 15%), cure time(7th day, 28th day) As a result, shear elastic modulus and damping ratio, which are ground dynamic parameter, are affected by the injection ratio of milk grout, cure time and water content.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.16 no.1
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• pp.139-146
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• 2021

This study studied the network between positive psychology capital, intention of start-up, and start-up behavior for learners who are willing to start a business. The research targets were intended to study the impact of the connection relationship between each variable, targeting nail art certification learners who are willing to start their own businesses. For this study, the measurement variables of positive psychology capital, intention of start-up, and start-up behavior were set, and the collected data were analyzed for connection-centeredness and eigenvector after data collection. The findings are as follows. First, some variables affecting the intention of start-up showed optimism, resilience and hope of positive psychology capital. Second, the intention to start a business was shown to have a significant impact on the behavior of start-ups, which, unlike the preceding study, appeared to be almost outside the network structure, showing that the behavior of start-ups was not significantly affected by other variables. Third, it is important to increase self-efficacy in positive psychological capital in order to increase the behavior of start-ups. Fourth, the analysis of the eigenvactor among positive psychology capital, intention of start-up, and start-up behavior showed optimism as some of the most central variables. In other words, prospective start-ups were found to be aware of the hardships and expected positive results in the future. The implications of this study, along with the intention and behavior of prospective entrepreneurs, are important factors in positive psychology capital, and suggest the importance of various educational programs that can be enhanced by positive psychology capital in start-up education or training programs and what should be taught. In addition, this study analyzed the network by approaching it from the perspective of positive psychology capital of prospective entrepreneurs in order to enhance the effectiveness of support programs for start-ups by the government, public institutions or universities in the future.

• Journal of Korea Entertainment Industry Association
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• v.14 no.2
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• pp.51-62
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• 2020

The study was conducted to verify the causality of the ability of high school and college dance majors to influence the successful goal orientation and how the change in goal affects the sense of dance performance self-confidence. In this regard, 172 dance majors were collected to collect data on their belief in dance ability, the direction of mastery goal of approach and avoidance, and the measure of confidence in dance performance, and the results of their studies were derived through correlation and structural equation analysis and path analysis. The analysis results showed reasonable factor structure and reliability based on the preceding study of feasibility analysis results between variables. Thus, the structural equation for the study variables confirmed that the theoretical hypothesis was suitable, and the path of each variable was verified through the path analysis. The analysis showed that the increased belief that ability can be improved by effort has been found to improve the effort and consequently the confidence in dancing. Also, the fixed belief that ability is not changing in a fixed sense has been found to affect the avoidance goal and reduce confidence. It can be interpreted that the more one believes that one can change one's ability by effort, the more one strengthens one's actions to achieve one's goal, thereby improving one's dance confidence. Therefore, it is deemed necessary for subsequent studies to explore whether the paths of these models differ by their major or dance careers, and to apply variables that can measure the success or failure of actual performances to enhance the explanatory power of these research variables.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.40 no.4
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• pp.261-273
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• 2022

This study aims to predict the land use demand of Seongnam-city using system dynamics and to simulate the effect of changes in family structure and land use density adjustment policy on land use demand. This study attempted to construct causal loop diagrams and an analysis model. The changes in land use demand over time were predicted through simulation results. As a result of the analysis, as of 2035, an additional supply of 2.08 km² for residential land and 1.36 km² for commercial land is required. Additionally, the current supply area of industrial land can meet the demand. Three policy experiments were conducted by changing the variable values in the basic model. In the first policy experiment, it was found that when the number of household members decreased sharply compared to the basic model, up to 7.99 km² of additional residential land were required. In the second policy experiment, if the apartment floor area ratio was raised from 200% to 300%, it was possible to meet the demand for residential land with the current supply area of Seongnam-city. In the third policy experiment, it was found that even if the average number of floors in the commercial area was raised from four to five and the building-to-land ratio in the commercial area was raised from 80% to 85%, the demand for commercial land exceeded the supply area of the commercial area in Seongnam-city. This study is meaningful in that it proposes a new analytical model for land use demand prediction using system dynamics, and empirically analyzes the model by applying the actual urban planning status and statistics of Seongnam-city.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.35 no.1
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• pp.29-34
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• 2022

In this paper, the floor acceleration for the seismic design of non-structural elements was evaluated using the core shape as a planar variable. Linear time history analysis using 20 models with 5 different planes and 4 different floors on each plane depending on the change in the shape (position and specific gravity) of the core in the square biaxially symmetric plane was performed. The analysis confirmed that the torsional amplification of the floor acceleration was up to 1.7 times in the plane subjected to eccentricity depending on the position of the core, and the effect of torsion was the greatest in the middle floor of the structure. In a plane where only the specific gravity of the core was changed without eccentricity, when the period was less than 0.4694 s, the maximum floor acceleration decreased in the lower floors and increased in the upper floors as the period increased. Conversely, when the period was 0.4694 s or more, it was confirmed that the floor acceleration increased in the lower part and decreased in the upper part as the period increased.