• Proceedings of the Korea Information Processing Society Conference
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• 2000.04a
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• pp.821-829
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• 2000

Over the past decade, the topic of work breakdown structure (WBS) has gained an increasing amount of attention from information technology professionals as an effective tool for managing the complexity of a large-scale information system development project. It is a method for planning and controlling a large-scale information system development. A WBS provides the basis for project organization, cost estimation, task scheduling, and contract management. Based on the authors' practical experience, this paper discusses how to establish a specific WBS and some considerations for developing a well-defined WBS. The model of WBS suggested in this study will provide useful insight and guidelines for establishing the spec-ific WBS for a large-scale information systems development.

• Korean Chemical Engineering Research
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• v.60 no.2
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• pp.295-299
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• 2022

In this paper, paint-free metallic plastic material, polypropylene (PP) and acrylonitrile styrene acrylate (ASA) materials were investigated on the applications for bumper skid plate and outside mirror housing parts. In order to maximize metallic effect, type, size and content of aluminum pigment were optimized based on flop index. Hybrid aluminum pigments with different aspect ratios were used to conceal weld lines. By controlling the fluidity of the material, the flow mark problem, generated on the surface of the part, was resolved. We also investigated the surface defects of flow and weld lines by using the developed modeling and simulation.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.33 no.6
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• pp.276-281
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• 2023

With the high design freedom of the additive manufacturing process, there is a growing interest in multi-dimensional lattice structures among researchers, who are studying intricate structural modeling that is challenging to produce using conventional manufacturing processes. In the case of titanium alloy implants for human insertion, a multi-dimensional lattice structure is employed to ensure compatibility with bones, adjusting strength and elastic modulus to levels similar to those of bones. Therefore, securing a database on the mechanical properties based on lattice structure design variables and the development of related simulation techniques are believed to efficiently facilitate the customization of implants. In this study, lattice structures were additively manufactured using Ti-6Al-4V alloy, and the elastic modulus was measured based on design parameters. The results were compared with simulations, and an approach to finite element analysis for accurate prediction of the elastic modulus was proposed.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.13 no.6
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• pp.304-308
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• 2003

By controlling the internal pressure in the cyclone separator, we investigated the separation charateristics of $Al_2O_3$, $Fe_2O_3$ particles with the internal pressure variation. 3-dimensional Langrangian approach was applied for the analysis of the particles separation, and then the minimum cut diameter of the separated particles and the separation rate were calculated through tracking the particle trajectories. The density of the argon gas for transporting particles was decreased corresponding the pressure decrease, consequently, caused the internal pressure drop in the cyclone separator. For that reason the finer particles were separated as the pressure was changed from an atmospheric pressure to an low pressure. Specifically, at 50 torr pressure, $Al_2O_3$ particles of the size of about 4 $\mu\textrm{m}$ and $Fe_2O_3$particles of about 3 $\mu\textrm{m}$ could be separated.

• International Journal of Human Ecology
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• v.16 no.1
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• pp.25-35
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• 2015

The primary purpose of this study was to examine to what extent adolescents' daily self-evaluation mediates the effect of experiencing intimacy in parent-adolescent interactions on positive peer interactions the next day, even after controlling for gender and grade level. We employed a daily diary method for seven days in a sample of 452 Korean adolescents, collecting checklist data at the end of each day. Data were analyzed by using hierarchical linear modeling. According to moderated multilevel mediation analyses, the variance of self-evaluation explained 83% of the variance in the lagged effect of parental intimacy on the next day peer interaction even after the upper-level effects of gender and grade level were accounted for. Forth graders were more likely than 7th graders to have a more positive view of themselves when they experienced parental intimacy the previous day. Girls were less likely to experience positive peer interactions when they perceived less intimacy with their parents the day before. Results suggested that it would be most effective for peer relationship programs to teach parents and adolescents how to experience intimacy in their daily interactions, particularly in ways that help adolescents to think more positively about themselves. It would be helpful for parents to learn about various ways to compliment and encourage the adolescent child in everyday conversations. Lastly, findings in grade level differences also suggest that these programs might be especially effective for 4th graders more than 7th graders.

• Journal of the Institute of Convergence Signal Processing
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• v.19 no.3
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• pp.110-117
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• 2018

The development of prosthetic hand or prosthetic leg equipment is steadily taking place globally. Though it would be difficult to create or feel the same way as a human hand, it would be a great for the amputated person if they can pick things up or do some movement as they want. It has become possible to develop low-cost prosthetic hand according to development of 3D printing technology. If people can develop personalized prosthetic equipment at similar prices to meet this trend, the utilization and penetration rate will be much higher. In this study, it describes how to develop a user-customizable prosthetic hand using 3D printing. To do this, the transformational parameters of prosthetic hand shape modeling are extracted as variability values, and the functions for controlling prosthetic hand motion are designed as software design patterns. This allows people who need a prosthetic hand to have their own prosthetic hand at a fast and affordable price.

• Journal of Nutrition and Health
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• v.55 no.2
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• pp.296-308
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• 2022

Purpose: To investigate the effect of a mother's modeling and feeding practices on the eating behavior of the children. Methods: From April to June 2018, 1,036 young children aged 2 to 6 years and their mothers in Gyeongsan, Gyeongsangbuk-do, were examined for their eating behavior and feeding practices using a verified dietary behavior test (DBT). The children's dietary behavior was classified into four categories: "access evasiveness", "sensory acuity", "hyperactivity", and "irregularity". The mother's eating behavior was classified into three categories: "pickiness", "negligence", and "irregularity", and feeding practice types were classified into two categories: "responsibility/monitoring", and "restriction/pressure". The differences between the groups were tested using the t-test, ANOVA, and Duncan's multiple range test. The influence of feeding practices on the children's eating behavior was analyzed by hierarchical regression analysis while controlling for the mother's modeling. Results: The problem rates of irregularity, negligence and pickiness in the mother's modeling were 33.7%, 22.8%, and 20.7%, respectively. An analysis of the mother's feeding practices revealed that responsibility/monitoring had a middle, high and low significance in 74.2%, 17.3%, and 8.5% of respondents, respectively and the risk rate of restriction/pressure when guiding children to eat was 15.3%. The problem rates for sensory acuity, access evasiveness, irregularity, and hyperactivity in children were 27.9%, 26.1%, 24.8%, and 22.0%, respectively. Among the four eating behavior characteristics of children, the child's access evasiveness and sensory acuity were more affected by their pickiness rather than the mother's feeding practices, and the child's hyperactivity was more influenced by feeding practices than the mother's eating behavior. The child's irregularity was similarly affected by the mother's eating behavior and feeding practices. Conclusion: Since the mother's eating behavior and feeding practices affect the children's eating behavior, a diet improvement program for children should consider not only the nutrition education of children but also the mother's eating behavior and provide the necessary intervention for feeding practices.

• Journal of the Korean Institute of Intelligent Systems
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• v.21 no.3
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• pp.372-377
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• 2011

This paper propose the robust stability algorithm for controlling a hybrid magnetic bearing system. The control object in the magnetic bearing system enables the rotor to rotate without any physical contact by using magnetic force. Generally, the system dynamics of the magnetic bearing system has severe nonlinearity and uncertainty so that it is not easy to obtain the control objective. For solving these problems, we propose the fuzzy modelling and robust control algorithm for hybrind magnetic bearing system. The sufficient conditions for robust controller are obtained in terms of solutions to linear matrix inequalities (LMIs). Simulation results for HMB are demonstrated to visualize the feasibility of the proposed method.

• Smart Structures and Systems
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• v.23 no.6
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• pp.565-577
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• 2019

One of the most effective countermeasures for mitigating cable vibration is to install mechanical dampers near the anchorage of the cable. Most of the dampers used in the field are so-called passive dampers where their parameters cannot be changed once designed. The parameters of passive dampers are usually determined based on the optimal damper force obtained from the universal design curve for linear dampers, which will provide a maximum additional damping for the cable. As the optimal damper force is chosen based on a predetermined principal vibration mode, passive dampers will be most effective if cable undergoes single-mode vibration where the vibration mode is the same as the principal mode used in the design. However, in the actual engineering practice, multi-mode vibrations are often observed for cables. Therefore, it is desirable to have dampers that can suppress different modes of cable vibrations simultaneously. In this paper, MR dampers are proposed for controlling multi-mode cable vibrations, because of its ability to change parameters and its adaptability of active control without inquiring large power resources. Although the highly nonlinear feature of the MR material leads to a relatively complex representation of its mathematical model, effective control strategies can still be derived for suppressing multi-mode cable vibrations based on nonlinear modelling, as proposed in this paper. Firstly, the nonlinear Bouc-wen model is employed to accurately portray the salient characteristics of the MR damper. Then, the desired optimal damper force is determined from the universal design curve of friction dampers. Finally, the input voltage (current) of MR damper corresponding to the desired optimal damper force is calculated from the nonlinear Bouc-wen model of the damper using a piecewise linear interpolation scheme. Numerical simulations are carried out to validate the effectiveness of the proposed control algorithm for mitigating multi-mode cable vibrations induced by different external excitations.

• Journal of Korean Society of Forest Science
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• v.112 no.2
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• pp.173-187
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• 2023

The forest protection policies implemented in South Korea have resulted in the significant accumulation of forest. Moreover, the associated public interest has also been closely evaluated. As forests mature, there arises a need for forest management (FM) practices, such as thinning and harvesting. It is therefore essential to perform a scientific analysis of the long-term effects of FM. In this study, conducted in Mt. Gariwang, the effect of FM on forest succession and wood production (WP) were evaluated based on changes in aboveground biomass (AGB) using the LANDIS-II model. The FM consists of three scenarios (Selection, Shelterwood, and Two-stories), characterized based on the harvest intensity, frequency, and period. The model was applied to changes in the forest over 200 years. All scenarios show that the total AGB decreased immediately after thinning and harvesting. However, AGB recovery time differed among scenarios, with recovery to preharvest level occurring from 15 to 50 years after harvest; further, after 200 years, harvested forests had a greater total AGB than forests without FMs In particular, the changes in AGB of each species was different depending on its shade tolerance. The AGB of currently dominant shade-intolerant and mid-tolerant species decreased dramatically after harvesting. However, shade-tolerant species, dominant in the understory, continued to grow but were not harvested due to their small size. The cumulative WP for each scenario was estimated at 545.6, 141.6, and 299.9 tons/ha in Selection, Shelterwood, and Two-stories, respectively. The composition of WP differed according to harvest intensity and period. Most WP originated from shade-intolerant and mid-tolerant species in the early period. Later, most WP was from shade-tolerant species, which became dominant. The modeling approach used in this study is capable of analyzing the long-term effects of FM on changes in forests and WP. This study can contribute to decision making to guide FM methods for a variety of purposes, including WP and controlling forest composition and structure.