• Transactions of Materials Processing
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• v.12 no.1
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• pp.18-25
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• 2003

This paper explains the process design for improving tool life in the conventional hot forging process. The thermal load and the thermal softening are happened by contact between the hotter billet and the cooler tools in hot forging process. Tool life decreases considerably due to the softening of the surface layer of a tool was caused by a high thermal load and long contact time between the tools and the billet. Also, tool life is to a large extent limited by wear, heat crack and plastic deformation in hot forging process. Above all, the main factors which affect die accuracy and tool life we wear and the plastic deformation of a tool. The newly developed techniques for predicting tool life are applied to estimate the production quantity for a spindle component and these techniques can be applied to improve the tool life in hot forging process.

• Journal of the Korea Furniture Society
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• v.19 no.1
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• pp.11-21
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• 2008

For ages, Furniture, it has been improved for human aesthetic needs as well as human life as a tool. In the 1960s, it's the age of an ideological conflict. And its war made the hippie-culture come out. And, it was economically bountiful. The epoch-making development of the scientific technology made the result of space development, conquering the moon in the first of the mankind. Made the appearance of the Anti-design against the modern design which was the also, it traditional values and the mainstream. The plastic has merits, low-priced, light, being perfectly able to do mass production of the all kind of shapes' furniture with all-desired colors. It was the wonderful material for the expression of the short-life character, the irony, the kitsch, and an intentional decoration to being chased by anti-design. And the result, the plastic furniture in the people's daily-life has well represented with reflecting the mind of the people in that age.

• Korean Institute of Interior Design Journal
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• no.27
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• pp.64-75
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• 2001

As living condition has improved, agreeable living environmental plans that reflect residential traits are needed from. the first stage of house remodeling or interior construction. At the request of above, we need systematically study about the householder's preference according to the life style. The purpose of this study is to suggest the case of preferred interior by understanding preferred Interior image and interior design elements. Document and questionnaire research are used as the method of study. The subjects of research wear 702 persons from 20th to 40th. Contents are constituted with general traits, life style and preferred interior image and the analysis of the materials is quantifical analysis using statistics. In the base of the theory of interior image and interior design elements appeared In the documents, measuring apparatus is made up and suggested preferred examples of interior design depend on life style by combining preferences.

• Journal of Power Electronics
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• v.9 no.4
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• pp.526-534
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• 2009

This paper introduces the electronic ballast for high pressure sodium (HPS) lamps which provides power regulation during the whole lamp life without using a closed-loop power control system, in spite of large variations of lamp characteristics resulting from lamp aging. The structure of the electronic ballast and the parameters of HPS lamps are described. A mathematical model for the ballast is developed and used for the design and analysis of the ballast. A design procedure is presented to design the ballast which provides intrinsic power regulation over the whole lamp life. To improve the technical specifications of the ballast, the practical and standard constraints are considered in the design. According to the design procedure, an electronic ballast for 250-W HPS lamps is designed. All theoretical analyses are verified with the help of a semi-industrial experimental setup. The results validate that the designed ballast provides power regulation during the whole lamp life.

• Korean Journal of Agricultural Science
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• v.43 no.3
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• pp.441-449
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• 2016

Agricultural tractors are designed using the empirical method due to the difficulty of measuring precise load cycles under various working conditions and soil types. Especially, directly drives various tractor implements, the power take off (PTO) gear. Therefore, alternative design methods using gear design software are needed for the optimal design of tractors. The objective of this study is to simulate fatigue life of the PTO gear according to the operating point of the tractor engine. The PTO gear was made with SCr415 alloy steel with carburizing and quenching treatments. The fatigue life of the PTO gear was simulated by using bending and contact stress according to the torque of the load levels. The PTO gear simulation was conducted by the KISSsoft commercial software for gear analysis. Bending and contact stress were calculated by the ISO 6336:2006 Method A and B. The simulation of fatigue life was calculated by the Miner's cumulative damage law. The total fatigue life of tractors can be estimated to 3,420 hours; thus, 3,420 hours of fatigue life were used in the simulation of the PTO gear of tractors. The main simulation results showed that the maximum fatigue life of the PTO gear was infinite fatigue life at maximum engine power. Minimum fatigue life of the PTO gear was 19.61 hours at 70% of the maximum engine power. Fatigue life of the PTO gear changed according to load of tractor. Therefore, tractor work data is needed for optimal design of the PTO gear.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1340-1345
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• 2003

In this paper, an integrated optimal design software system for structural components has been developed which interfaces existing commercial codes for CAD, CAE and Optimization. They include specialized optimal design software codes such as iSIGHT and VisualDOC, optimization module imbedded in CAD software developed by CAD developers, and optimal design software systems based on API of commercial CAD software. The advantages of the CAD imbedded optimal design approach and those of specialized optimal design software are taken to develop the system. The user defines optimal design formulation in the user interface for problem definition in the CAD control stage, where design variables are directly selectable from the CAD model and various properties and performance functions defined. The commercial CAD codes, Open I-DEAS are used for the development. The resulting software is minimally connected to CAD and CAE systems while keeping maximum independence from each other. This assures flexibility and freedom for problem definition. Fatigue life optimization is taken as a nontrivial application area. As a specific example, the shape design of a knuckle part of an automobile is performed, where the minimum fatigue life over the material domain in terms of the number of cycles of a curb strike are maximized under the constraint of not exceeding the current mass. The fatigue life has been improved by four times of the initial life. The developed software is illustrated to maintain the advantages of existing optimal design software systems while improving independency and flexibility.

• Human Ecology Research
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• v.60 no.2
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• pp.243-256
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• 2022

Undergraduate freshmen are currently encountering numerous difficulties in adapting to college life due to the outbreak of the COVID-19 pandemic. Thus, several studies have underlined the need to develop interventions focused on undergraduate students' resilience during this situation. We adopted the service design method in identifying the difficulties faced by undergraduate freshmen during this pandemic, and also developed interventions for raising their resilience. The service design method is a person-centered approach which adopts the user's viewpoint in developing solutions, thereby enabling their requirements to be satisfied. Surveys and in-depth interviews revealed that undergraduate freshmen were experiencing psycho-emotional problems which were derived from schoolwork and college life. This is particularly the case with students who are experiencing greater levels of academic difficulty, and were insufficiently equipped with resources such as stress-coping strategies and social support. Four undergraduate freshmen were recruited online to test the effectiveness of a resource promotion program aimed at enhancing their resilience. This program has proved to be helpful in relieving daily/academic stress and in building relationships among freshmen, regarding which the participants showed a high level of satisfaction. The results were discussed by focusing on psycho-emotional difficulties and resources of college freshmen, as well as the effectiveness of the resource promotion program. Further research is required in order to verify the efficiency of the program and to confirm conclusions.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.4
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• pp.179-185
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• 2008

The purpose of this paper is to propose a systematic method on the weld pitch design of a vehicle sub-frame considering the fatigue life of spot welding points. The input data, which perform the fatigue analysis on the spot welding nuggets, are obtained by both the dynamic analysis of the multi-body vehicle model passing through the virtual proving ground of a typical Belgian road and the quasi-static analysis with the finite element model of the vehicle sub-frame. By utilizing the life cycle data obtained from the fatigue analysis, the welding points to perform the pitch change are determined. The sensitivity analysis on the fatigue life of the welding points is carried out by using the three-level orthogonal array design, and through the results of the sensitivity analysis, the best combination on the welding pitch is determined. This study shows that as compared with the baseline design, the sub-frame redesigned by the proposed technique improves the fatigue life about 7 percent while reducing the number of welding points about 19 percent.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.9
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• pp.85-94
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• 2004

As over 70% of the total life cycle cost (LCC) of a product is committed at the early design stage, designers are in an important position to substantially reduce the LCC of the products they design by giving due to life cycle implications of their design decisions. During early design stages, there may be competing concepts with dramatic differences. In addition, the detailed information is scarce and decisions must be made quickly. Thus, both the overhead in developing parametric LCC models fur a wide range of concepts, and the lack of detailed information make the application of traditional LCC models impractical. A different approach is needed, because a traditional LCC method is to be incorporated in the very early design stages. This paper explores an approximate method for providing the preliminary LCC, Learning algorithms trained to use the known characteristics of existing products might allow the LCC of new products to be approximated quickly during the conceptual design phase without the overhead of defining new LCC models. Artificial neural networks are trained to generalize product attributes and LCC data from pre-existing LCC studies. Then the product designers query the trained artificial model with new high-level product attribute data to quickly obtain an LCC for a new product concept. Foundations fur the learning LCC approach are established, and then an application is provided.

• Korean Institute of Interior Design Journal
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• v.14 no.6 s.53
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• pp.202-211
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• 2005

The future of design relies much on and is only ensured by the fundamental understanding of the dynamics between the ecosystem of nature and that of humans; therefore, having an eco-mind is essential. This study establishes ecological design strategies coinciding with the furniture design process and the furniture product life cycle in production, distribution, and end-of-life. In addition, it provides an overall direction with guidelines for ecological furniture design. The presented strategies focus on the Development of a New Concept; the Optimized Use of Physical Materials-functionality and utility; the Optimized Production; the Optimized Distribution System; and the Optimized End-of-life System. Through taking these steps, we can not only preserve our natural environment and Improve our lives, but also create optimal furniture design which corresponds and integrate with the ecosystem.