• Clean Technology
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• v.28 no.3
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• pp.227-231
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• 2022

The demand for high-voltage power devices is rising in various industries, but especially in the transportation industry due to autonomous driving and electric vehicles. IGBT module parts of 3.3 kV or more are used in the power propulsion control device of electric vehicles, and the procurement of these parts for new construction and maintenance is increasing every year. In addition, research to optimize high-voltage IGBT parts is urgently required to overcome their very high technology entry barrier. For the development of high-voltage IGBT devices over 3.3 kV, the resistivity range setting of the wafer and the optimal conditions for major unit processes are important variables. Among the manufacturing processes to secure the optimal junction depth, the optimization of the diffusion process, which is one step of the unit process, was examined. In the diffusion process, the type of gas injected, the injection time, and the injection temperature are the main variables. In this study, the range of wafer resistance (Ω cm) was set for the development of high voltage IGBT devices through unit process simulation. Additionally, the well drive in (WDR) condition optimization of the diffusion process according to temperature was studied. The junction depth was 7.4 to7.5 ㎛ for a ring pattern width of 23.5 to25.87 ㎛, which can be optimized for supporting 3.3 kV high voltage power devices.

• The Journal of the Convergence on Culture Technology
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• v.9 no.3
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• pp.669-676
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• 2023

This study analyzed the relationship between major parameters and numerical analysis results according to various excavations conducted around the urban railway, application of machine learning techniques and verified the scope of influence of the adjacent excavation on the existing urban railway box structure and the appropriateness of the safety area. This study targeted the actual negotiated adjacent excavation works and box structures around the urban railway, and the analysis was conducted on the most representative two-line box structures. The analysis confirmed that the difference in depth of urban railway, excavation depth of adjacent excavation, and depth of underground water level are important parameters, and the difference in excavation depth of adjacent excavation is the parameter that affects the behavior of underground box structures and is an important requirement for setting safety areas. In particular, the deeper the depth of the adjacent excavation work, the greater the effect on the deflection of the underground box structure, and the horizontal separation distance, one of the important requirements for determining the management grade of the existing adjacent excavation work, is relatively small.

• Korean Journal of Environmental Agriculture
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• v.16 no.2
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• pp.130-135
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• 1997

Tomatoes are flooded differently 0, 5, 10 and 15cm, according to the developing stages such as flowering stage under the condition of greenhouse. Along with this, they are treated according to the time condition such as 6, 12, 24, 48 and 120 hours. The results obtained are summarized as follows. Plant height decreased in the depth of $0{\sim}10cm$ for over 48 hours, in the depth of 15cm for over 24 hours. Number of leaves was the same as in control, and it decreased over. Number of flowers and fruit setting of individuals decreased conspicuously according as the depth and the hours got greater and longer. Adventitious root occurred remarkably in the depth of $0{\sim}10cm$, for over 24 hours and in the depth of 15cm, 12 hours. Epinastic curvature increased greatly as the depth and the hours got greater and longer. Diffusion resistance of stomata cell increased as the depth and the hours got greater and longer. Diseases occurred conspicuously as the hours of flooding got longer rather than as the depth greater. The preventing of diseases caused by insecticide was observed, but it was not greater than in the seedling and transplanting stage. Fertilization was effective in the case of increasing the weight of shoot. Number of fruits per plant did not decrease in the depth of 0cm up to 24 hours, but decreased on the deeper level of flooding and increased as the hours got longer. Moreover with the exception of 120 hours per respective depth of the treatment, average weight of a fruit got greater as the depth and the hours got greater and longer. In the case of epinastic curvature and diffusion resistance, there was negative correlation between all the other investigated characters and positive correlation between weight of a fruits and average weight of a fruit.

• Korean Journal of Community Nutrition
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• v.22 no.3
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• pp.238-247
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• 2017

Objectives: This study was conducted to investigate providers' perspectives on current challenges in implementing a program for prevention and management of childhood obesity and adoption of mobile phone as a potential solution of leveraging multimodal delivery and support in a school setting. Methods: The qualitative data were collected through face-to-face in-depth interviews with 23 elementary-school teachers, 6 pediatricians, and 6 dieticians from community health centers and analyzed using a qualitative research methodology. Results: Current challenges and potential solutions of obesity-prevention and -management program for obesity program for elementary school children were deduced as two themes each. Lack of tailored intervention due to limited recipient motivation, lack of individualized behavioral intervention, and different environmental conditions can be solvable by mobile technology-based personalized intervention which brings about interactive recipient participation, customized behavioral intervention, and ubiquitous accessibility. Lack of sustainable management due to stigmatization, limited interactions between program providers and inconsistent administrative support can be handled by multimodal support based on school setting using mobile platform providing education of health promoting behaviors toward larger scale and interactive networking between program participants, and minimizing administrative burden. Conclusions: Adoption of mobile-based health management program may overcome current limitations of child obesity program such as lack of tailored intervention and sustainable management via personalized intervention and multimodal supports although some concerns such as increased screen time need to be carefully considered in a further study.

• Journal of the Korea Society of Computer and Information
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• v.25 no.5
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• pp.81-90
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• 2020

In this paper, we propose setting measurement point in the 3D scan data based on the manual measurement data. The optimal 3D body scan postures and measurement points for automatic measurement of breast were set up. The outer breast point may be different depending on the body shape or standing posture as it is on the line connected from the bisecting point of the lateral waist thickness to front armpit point. Therefore, it is necessary to consider the breast-related outer point proposed in this study. And many researches need to reduce the differences between MAM and 3D dimension items associated with the upper breast point. When measuring depth, the difference by pressing in MAM should be taken into account. And the differences in flexion depending on breast type can make a difference in the 3D measurement. So the measurement method in 3D scan should be further studied depending on the types of breast and verified by multiple subjects.

• Journal of the Korea Convergence Society
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• v.12 no.10
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• pp.151-160
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• 2021

This study aims to establish the most appropriate festival concept in the post-corona era through in-depth analysis and discussion of local festivals, and to propose a tourism festival for international competitiveness and tourist satisfaction. It also aims to contribute to revitalization of local tourism and the revitalization of the local economy by establishing and implementing a new festival concept in the post-corona era. The results of the review of previous studies, empirical research, and comprehensive meta-analysis showed that it was necessary to change the festival concept setting. In the post-Corona era, it is necessary to build a concept through an online video platform, establish a safety packaged tourism festival prevention system, and hold the most distributed tourist festival time and space of the tourist festival and space as much as possible. In addition, it appeared that it was necessary to plan and implement the village tourism festival through the participation of residents, and to apply the concept of a tourism festival enjoyed by small neighbors and neighbors in the village unit.

• Journal of the Korean Geotechnical Society
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• v.38 no.8
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• pp.67-74
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• 2022

The setting of the target area for ground stability evaluation during ground excavation is categorized into theoretical and empirical estimation methods and numerical analysis methods. Generally, the applied theoretical and empirical estimation methods include those by Peck (1969), Caspe (1966), and Clough et al. (1990). The numerical analysis method comprehensively considered the current status of the task section (maximum excavation depth section, ground condition vulnerable section, etc.). It reflected the results of performing two and three-dimensional numerical analyses on the weakest section. Therefore, this study shows an example of setting the scope of influence when excavating the vertical and tunnel sections of a 000-line double-track private investment project through the above theoretical, empirical, and numerical analysis methods.

• Journal of the Korea Concrete Institute
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• v.21 no.1
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• pp.55-64
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• 2009

This study is aimed to derive the optimum mix proportion of the combined self compacting concrete according to cement types (blast-furnace slag cement and belite cement) and to propose the basic data to field construction work after evaluating the quality properties. Specially, lime stone powder (LSP) as binder and viscosity agent are used in the combined self compacting concrete because slurry wall of an underground LNG storage tank should be kept stability of quality during concrete working. Replacement ratio of LSP is determined by confined water ratio test and main design factors including fine aggregate ratio ($S_r$), coarse aggregate ratio ($G_v$) and water-cement ratio (W/C) are selected. Also, quality properties including setting time, bleeding content, shortening depth and hydration heat on the optimum mix proportion of the combined self compacting concrete according to cement type are compared and analyzed. As test results, the optimum mix proportion of the combined self compacting concrete according to cement type is as followings. 1) Slag cement type-replacement ratio of LSP 13.5%, $S_r$ 47% and W/C 41%. 2) Belite cement type-replacement ratio of LSP 42.7%, Sr 43% and W/C 51%. But optimum coarse aggregate ratio is 53% regardless of cement types. Also, as test results regarding setting time, bleeding content, shortening depth and hydration heat of the combined self compacting concrete by cement type, belite cement type is most stable in the quality properties and is to apply the actual construction work.

• Journal of the Korea Concrete Institute
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• v.29 no.3
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• pp.315-322
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• 2017

The purpose of this study is to investigate experimentally the construction performances and economical evaluation of the self-compacting concrete in actual site work after selecting the optimum mix proportions according to cementitious materials. Slag cement type of 46.5% slag powder and belite cement of 51.4% $C_2S$ content, lime stone powder as binders are selected for site experiment including water cement ratio. Also, test items for optimum mix proportion are as followings ; (1) Slump flow, 500 mm reaching time, V-type flowing time and U-box height (2) Setting time, bleeding, shortening depth and adiabatic temperature rising (3) Mixing time in plant (4) Concrete quantity and cost, quality control in actual concrete work. As test results, (4) Optimum water-cement ratio ; Slag cement type 41.0% and belite cement 51.0% (2) Setting time and bleeding finishing time of slag cement are faster, bleeding content of slag cement is higher, shortening depth and adiabatic temperature rising of belite cement type are lower (3) Optimum mixing time in batcher plant is 75 seconds and concrete productive capacity is about $100{\sim}110m^3/hr$. (4) Belite cement type is lower than slag cement type in material cost 14.0%, and concrete quantity in actual concreting work save 3.3% in case of belite cement type. Therefore, self-compacting concrete of belite cement type is definitely superior to that of slag cement type in various test items without compressive strength development.

• Journal of the Korean Geotechnical Society
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• v.20 no.9
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• pp.25-32
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• 2004

Some amount of cements can be added into the soil with high water content to improve the engineering properties. In such a case, it is difficult to predict and figure out the phase changes of the soil-cement mixture which is closely associated with workability of the soil-cement mixture. Changes in heat of hydration and hardness of the cement pastes are known to provide the useful information about the phase changes of the soil-cement mixtures. In this study, heat of hydration and cone penetration depth were measured from the specimens of cement paste and 3 soil-cement mixtures. From the experimental results, it was found that the phase changes of the soil-cement mixtures are the same as those of cement paste, and that shear strength of the mixtures abruptly increases when the heat of hydration is minimum. Initial setting time of the mixtures coincides with the state when fall cone penetration depth was 1.0 mm and it is defined as plastic limit of the mixtures. Initial setting time of the mixtures is retarded as soil/cement ratio is increased. Measurements of heat of hydration and fall cone apparatus could be the useful tools to predict the phase changes of tile soil-cement mixtures.