• Structural Engineering and Mechanics
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• v.66 no.3
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• pp.343-351
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• 2018

Brazilian disc test is one of the most widely used experiments in the literature of geo-mechanics. In this work, the pre-holed concrete Brazilian disc specimens are numerically modelled by a two-dimensional discrete element approach. The cracks initiations, propagations and coalescences in the numerically simulated Brazilian discs (each containing a single cylindrical hole and or multiple holes) are studied. The pre-holed Brazilian discs are numerically tested under Brazilian test conditions. The single-holed Brazilian discs with different ratios of the diameter of the holes to that of the disc radius are modelled first. The breakage load in the ring type disc specimens containing an internal hole with varying diameters is measured and the crack propagation mechanism around the wall of the ring is investigated. The crack propagation and coalescence mechanisms are also studied for the case of multi-holes' concrete Brazilian discs. The numerical and experimental results show that the breaking mechanism of the pre-holed disc specimens is mainly due to the initiation of the radially induced tensile cracks which are growth from the surface of the central hole. Radially cracks propagated toward the direction of diametrical loading. It has been observed that for the case of disc specimens with multiple holes under diametrical compressive loading, the breaking process of the modelled specimens may occur due to the simultaneous cracks propagation and cracks coalescence phenomena. These results also show that as the hole diameter and the number of the holes increases both the failure stress and the crack initiation stress decreases. The experimental results already exist in the literature are quit agree with the proposed numerical simulation results which validates this simulation procedure.

• Journal of the Society of Naval Architects of Korea
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• v.50 no.1
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• pp.14-24
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• 2013

The marine leisure industry in Korea has been the focus of the power of economic growth and the creation of jobs in recent years. In this regard, many studies concerning marine leisure are on-going in various fields. In this paper, developed a layout system and algorithm can resolve the factory and facility layout problem. For a layout design of leisure-boat factories, the leisure-boat production process is analyzed in order to derive standard production space elements for the layout of the factory. Based on the results, a draft design of the factory layout is carried out based on the manpower planning data, as well as the characteristics and relationships of each process data. A layout design of this paper can be verified through a factory simulation solution and we suggest the verification method using a SBD(simulation based design) methodology. The layout system takes into account the user's accessibility and extendibility, so it is web-oriented and uses RIA (rich Internet Application) technology. Furthermore, the system and layout algorithm of this paper are verified with samples data that show the efficient factory arrangement and practical application method.

• Journal of the Korea Convergence Society
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• v.11 no.9
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• pp.15-20
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• 2020

Software-related training can be considered essential in situations where software is an important factor in national innovation, growth and value creation. As one of the implementation methods for engineering education, various education through virtual simulations that can educate difficult situations in a similar environment are being conducted. Recently, the construction of smart factories at production and manufacturing sites is spreading, and product inspections using vision systems are being conducted. However, it has many difficulties due to lack of operation technology of vision system, but it requires a lot of cost to construct the system for education of vision system. In this paper, provide an educational virtual simulation model that integrates computer and physics engine camera functions and can extract and transmit video. It is possible to generate an image of 30Hz or more at an average of 35.4FPS of the experimental results of the proposed model, and it is possible to send and receive images in a time of 22.7ms, which can be utilized in an educational virtual simulation educational environment.

• Journal of the Semiconductor & Display Technology
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• v.22 no.1
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• pp.134-138
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• 2023

This study focuses on the analysis of the results of computational fluid dynamics simulations of mist-chemical vapor deposition for the growth of an epitaxial wafer in power semiconductor technology using artificial intelligence techniques. The conventional approach of predicting the uniformity of the deposited layer using computational fluid dynamics and design of experimental takes considerable time. To overcome this, artificial intelligence method, which is widely used for optimization, automation, and prediction in various fields, was utilized to analyze the computational fluid dynamics simulation results. The computational fluid dynamics simulation results were analyzed using a supervised deep neural network model for regression analysis. The predicted results were evaluated quantitatively using Euclidean distance calculations. And the Bayesian optimization was used to derive the optimal condition, which results obtained through deep neural network training showed a discrepancy of approximately 4% when compared to the results obtained through computational fluid dynamics analysis. resulted in an increase of 146.2% compared to the previous computational fluid dynamics simulation results. These results are expected to have practical applications in various fields.

• Journal of Advanced Technology Convergence
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• v.2 no.3
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• pp.33-41
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• 2023

This study aimed to improve the quality of classes through the application experience analysis after applying the adult nursing simulation practice modules with PBL. Quantitative and qualitative data such as from satisfaction, validity, self-reflection, and lecture evaluation in 68 nursing students were analyzed after the semester. Satisfaction was 4.64 points out of 5 points, and 'I want to recommend this class to other friends' was the highest. It was appropriate for the validity as 64.7% to 100% positve answer. From the qualitative data analysis of lecture evaluation, it was categorized into 5 thematic groups : 'increased immersion related to a lively class environment', 'growth of knowledge and skills through learners' active participation', 'improvement of mutual collaboration skills through team-based problem-solving process', 'Improvement of problem-solving ability through situational crisis coping process' and 'Improvement of individual comprehension through close teaching'. The continuous development of PBL learning strategies and development of various scenarios are required in the future.

• Horticultural Science & Technology
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• v.33 no.6
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• pp.911-922
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• 2015

This study was carried out to evaluate growth characteristics of Kimchi cabbage cultivated in various highland areas, and to create a predicting model for the production of highland Kimchi cabbage based on the growth parameters and climatic elements. Regression model for the estimation of head weight was designed with non-destructive measured growth variables (NDGV) such as leaf length (LL), leaf width (LW), head height (HH), head width (HW), and growing degree days (GDD), which was $y=6897.5-3.57{\times}GDD-136{\times}LW+116{\times}PH+155{\times}HH-423{\times}HW+0.28{\times}HH{\times}HW{\times}HW$, ($r^2=0.989$), and was improved by using compensation terms such as the ratio (LW estimated with GDD/measured LW ), leaf growth rate by soil moisture, and relative growth rate of leaf during drought period. In addition, we proposed Excel spreadsheet model for simulation of yield prediction of highland Kimchi cabbage. This Excel spreadsheet was composed four different sheets; growth data sheet measured at famer's field, daily average temperature data sheet for calculating GDD, soil moisture content data sheet for evaluating the soil water effect on leaf growth, and equation sheet for simulating the estimation of production. This Excel spreadsheet model can be practically used for predicting the production of highland Kimchi cabbage, which was calculated by (acreage of cultivation) ${\times}$ (number of plants) ${\times}$ (head weight estimated with growth variables and GDD) ${\times}$ (compensation terms derived relationship of GDD and growth by soil moisture) ${\times}$ (marketable head rate).

• Analyses & Alternatives
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• v.7 no.2
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• pp.35-77
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• 2023

This study aims to solve the entangled loop between demographic transition (DT) and economic growth by analyzing cross-country data. We undertake a national-level group analysis to verify the compressed transition of demographic variables over time. Assuming that the LA (latecomer advantage) on DT over time exists, we verify that the DT of the latecomer is compressed by providing a formal proof of LA on DT over income. As a DT has the double-kinked functions of income, we check them in multiple aspects: early maturation, leftward threshold, and steeper descent under a contour map and econometric methods. We find that the developing countries (the latecomer) have speedy DT (CDT, compressed DT) as well as speedy income such that DT of the latecomers starts at lower levels of income, lasts for a shorter period, and finishes at the earlier stage of economic development compared to that of developed countries (the early mover). To check the balance of DT, we classify countries into four groups of DT---balanced, slow, unilateral, and rapid transition countries. We identify that the main causes of rapid transition are due to the strong family planning programs of the government. Finally, we check the effect of latecomer's CDT on economic growth inversely: we undertake the simulation of the CDT effect on economic growth and the aging process for the latecomer. A worrying result is that the CDT of the latecomer shows a sharp upturn of the working-age population, followed by a sharp downturn in a short period. Compared to early-mover countries, the latecomer countries cannot buy more time to accommodate the workable population for the period of demographic bonus and prepare their aging societies for demographic onus. Thus, we conclude that CDT is not necessarily advantageous to developing countries. These outcomes of the latecomer's CDT can be re-interpreted as follows. Developing countries need power sources to pump up economic development, such as the following production factors: labor, physical and financial capital, and economic systems. As for labor, the properties of early maturation and leftward thresholds on DTs of the latecomer mean that demographic movement occurs at an unusually early stage of economic development; this is similar to a plane that leaks fuel before or just before take-off, with the result that it no longer flies higher or farther. What is worse, the property of steeper descent represents the falling speed of a plane so that it cannot be sustained at higher levels, and then plummets to all-time lows.

• Korean Journal of Agricultural and Forest Meteorology
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• v.4 no.4
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• pp.224-236
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• 2002

A long-term growth simulation was performed at 496 land units in the western coastal plains (WCP) of North Korea to test the potential adaptability of each land unit for growing South Korean rice cultivars. The land units for rice cultivation (CZU), each of them represented by a geographically referenced 5 by 5 km grid tell, were identified by analyzing satellite remote sensing data. Surfaces of monthly climatic normals for daily maximum and minimum temperature, precipitation number of rain days and solar radiation were generated at a 1 by 1 km interval by spatial statistical methods using observed data at 51 synoptic weather stations in North and South Korea during 1981-2000. Grid cells felling within a same CZU and, at the same time, corresponding to the satellite data- identified rice growing pixels were extracted and aggregated to make a spatially explicit climatic normals relevant to the rice growing area of the CZU. Daily weather dataset for 30 years was randomly generated from the monthly climatic normals of each CZU. Growth and development parameters of CERES-rice model suitable for 11 major South Korean cultivars were derived from long-term field observations. Eight treatments comprised of 2 transplanting dates $\times$ 2 cropping systems $\times$ 2 irrigation methods were assigned to each cultivar. Each treatment was simulated with the randomly generated 30 years' daily weather data (from planting to physiological maturity) for 496 land units in WCP to simulate the growth and yield responses to the interannual climate variation. The same model was run with the input data from the 3 major crop experiment stations in South Korea to obtain a 30 year normal performance of each cultivar, which was used as a "reference" for comparison. Results were analyzed with respect to spatial and temporal variation in yield and maturity, and used to evaluate the suitability of each land unit for growing a specific South Korean cultivar. The results may be utilized as decision aids for agrotechnology transfer to North Korea, for example, germplasm evaluation, resource allocation and crop calendar preparation.

• Journal of Mechanical Science and Technology
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• v.16 no.11
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• pp.1435-1439
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• 2002

This paper presents a form of the cohesive surface separation potential, which can produce potential curves by varying a single dimensionless parameter. Results show that a partial modification of Xu and Needleman's (1994) cohesive surface separation potential makes it possible to present the other potential corves as a special case as long as the normal separation is concerned. The proposed potential may describe interfacial debonding-crack initiation and growth-character of materials and, through numerical simulation, provide an insight for the effect of different cohesive surface separation potentials on the interfacial debonding.

• Korean Journal of Materials Research
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• v.14 no.3
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• pp.175-180
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• 2004

SiC nanotubes were synthesized by CNT-confined reaction. Evaporated SiO gas reacted with carbon nanotubes by VS growth mechanism. By confineded reaction, carbon nanotube was changed to SiC nanotube, and synthesized SiC nanotube was filled partly by the gas reaction in the nanotubes. SiC nanotube's mean diameters were not changed than carbon nanotubes because of means ratio of $CO_2$ and SiO gas was maintained evenly during the process. This result was same of data of simulation. By TEM observastion, SiC nanotube was filled by reaction of inner wall of CNT and SiO gas through the VS reactions. Converted SiC nanotube's compositions were revealed Si and C of 1: 1 ratios at all sites of nanotube by EDS.