• Journal of the Society of Naval Architects of Korea
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• v.59 no.3
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• pp.183-191
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• 2022

A design method for a propeller type rim-driven axial-flow turbine for a micro-hydropower system is presented. The turbine consists of pre-stator, impeller and post-stator, where the pre-stator plays a role as a guide vane to provide circumferential velocity to the on-coming flow, and the impeller as a rotational power generator by absorbing angular momentum of the flow. BEM(Blade Element Method), which is based on the turbine Euler equation, is employed to design the pre-stator and impeller blades. NACA 66 thickness form and a=0.8 mean camber line, which is widely accepted as a marine propeller blade section, is used for the pre-stator and turbine blade section. A CFD method, derived from the discretization of the RANS equations, is applied for the analysis of the designed turbine system. The design conditions of the turbine is confirmed by the CFD calculation. Turbine characteristic curve is calculated by the CFD method, in order to provide the performance characteristics at off-design operation conditions. The proposed procedures for the design of a propeller type rim-driven axial-flow turbine are established and confirmed by the CFD analysis.

• 한국HCI학회:학술대회논문집
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• 2008.02b
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• pp.227-232
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• 2008

Since 2000, there have been many changes in the residential types, such as an intelligent apartment which integrates both resting space and production space with comfort able, pleasant and safe environments based on internet systems. As the result of the rapid decrease in the birth rate and the prolonged lifespan around the world, it is expected that we will enter into an aging society by 2026. With such the expected change in the living patterns, many issues concerning the increased number of the elderly people have emerged as major social problems such as changes of family formation, its function and values, responsibility of caring for the aged, health and medical care, habitation policies and so on, and it is required to reconsider the social awareness on the living qualities of each old person. However, we have not yet satisfied such requirements with appropriate policies for the improvement of the living environment for them. It is considered, therefore, that we need to develop a new tool that, according to our goals, can give us a broad understanding on several considerations in designing the future homes for the elder people, making it possible to check the process changed by residents' needs in real time and apply it immediately to the space. As we have seen, it is required that spatial design process and design methodology should be considered in designing the homes for the aged for the pre-occupancy design evaluation.

• Journal of electromagnetic engineering and science
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• v.3 no.2
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• pp.111-117
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• 2003

We propose a diode-based RF pre-distorter with various gain and phase characteristics, for non-linearity compensation of RF power amplifiers. This pre-distorter results in the removal of the diode- and configuration-dependent characteristics in the conventional diode-based RF pre-distorters. We have analyzed the operation principle of the proposed pre-distorter. The results show that gain and phase characteristics of the pre-distorter in all four quadrants are achieved. Several power amplifiers and test signals are used for verifying the performance of the proposed diode-based RF pre-distorter.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1998.10a
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• pp.176-179
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• 1998

In structural analysis using FEM or BEM, pre_ and post_processor is necessary pre_ and post_processor and analyzer use same structural model. But many other tasks related to structural design, such as optimization, design of layout, etc, do not share that model in spite of their resemblance of requiring data. So, a pre_ and post_ processor was developed using a relational database managing system. Developed system uses the DBMS as a data storage and interacts with it using SQL interface. In this way, many other tasks that uses same structural data can be developed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.628-632
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• 2000

In the recent day, shielding can was made of permalloy materials for automobile display instrument. The good roundness has an effect on magnetic property such as the low coercivity and the high permeability. But the products having the roundness is transformed by the heat treatment, the sending to the company and the assembly process. So for the stiffness of the edge, it is necessary for hemming process to be added in the deep drawing process. And it has the good appearance to create a smooth edge rather than a razor edge with urr. In this paper, it is controlled to get the best hemming product by the Pre-hemming angle($105^{\circ}$, $120^{\circ}$, $135^{\circ}$). And Possible process and tool design modification, which may lead to quality improvement in hemming were tested experimentally and using FEM. The commercial finite element program PAM-STAMPTM was used to simulate the pre-hemming process and hemming process, and the predictions were compared with experimental results according to the pre-hemming angle.

• Journal of the Korea Fashion and Costume Design Association
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• v.5 no.3
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• pp.15-23
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• 2003

Chestnut trees have been used as a dyeing material, which are grow naturally, are cultivated all the area of Korea. So, there is abundant amount of the materials and they have better colorfastness than other natural dyeing materials. But chestnut husk extract is good at silk and wool fabrics, not cotton fabrics. That's why many methods using chestnut extraction for dyeing are being studied. But most of them depend on treatment method with chemical material which doesn't fit with the aim, using natural materials. Therefore in this research, we used protein pre-treatment method which is dyeing chestnut husk extract after treating at cotton fabrics with bean sap. And we studied the effect of dyeability of chestnut husk extract to cotton fabrics. As a result of pre-treatment of bean sap at cotton fabrics, dyeability was increased. Besides laundering fastness, dry cleaning fastness, perspiration fastness and light fastness were almost increased.

• Journal of Industrial Technology
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• v.26 no.A
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• pp.47-54
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• 2006

To improve passenger safety, seat belt systems with pre-tensioner that tightens seat belt webbing using explosive just before collision are widely used these days. Even though seatbelt must not unlatched without passengers' operation. explosive power of pre-tensioner can cause unlocking of a buckle. To prevent the unlocking, an anti-g mass that blocks displacement of the release button has been attached to the buckle. In this study, the dynamics and statics of locking mechanism associated with operation of anti-g buckle has been theoretically investigated, and important design variables that affect the operation of anti-g buckle have been identified. Through the total seat belt system's dynamic simulation using force and displacement inputs obtained from seat belt sled test, design of the proposed anti-g buckle has been validated.

• Journal of the Korean Society of Marine Environment & Safety
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• v.2 no.1
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• pp.89-95
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• 1996

This paper describes a fuzzy controlled pre-chlorination technique for purifying the pulluted raw water in water purification lants. For the purpose of obtaining the high quality water, the appropriate pre-chlorine dosage rate has to be continuously adjusted according to a change in quality of a intake raw water, weather, solar nergy mount, temperature and etc. Therefore, the method of expressing an expert's empirical knowledge cumulated from his past carrier by fuzzy reasoning and the fuzzy controller design technique is necessary.In this paper fuzzy membership functions and rules accordingto emprircal knowledge and experimental field data were obtained, And also fuzzy cintriller design using four feedforward components for the determination of pre-chlorine dosage rate and four feedback ones for the compensation of its dosage rate with residual chlorine and its change rate, was executed.

• Journal of Korean Elementary Science Education
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• v.31 no.2
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• pp.227-242
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• 2012

This research explores the scientific reasoning of pre-service elementary teachers in experimental design. The article focuses on pre-service teachers' responses to the questions in the worksheets which involve making their knowledge claims on extinguishing of a burning candle in a closed container, evaluating anomalous data, and designing experiment to test their ideas. Their responses are interpreted in terms of categories developed by Tytler and Peterson(2003, 2004). The interrelationship between conceptual knowledge and scientific reasoning is explored using the data. It is argued that coordination of ideas and evidence must be emphasized in the scientific investigations rather than fair test.

• KCI Concrete Journal
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• v.12 no.2
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• pp.3-10
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• 2000

A computer program, named NEO-PCBRG, for the analysis and design of prestressed con-crete(PSC) bridges was developed using the finite element method. NEO-PCBRG can predict the response of PSC bridges throughout the various stages of construction and service. NEO-PCBRG has both pre- and post-processing capabilities. Pre-processing refers to all the neces- sary steps required to prepare a virtual prototype, more commonly termed a varied model for analysis. Post-processing here stands for the step in which the results from the analysis are reviewed and interpreted. In order to allow for the easy and convenient execution of the entire procedure, NEO-PCBRG was developed using computer graphics in the Visual Basic pro- gramming language. In conclusion, this study presents a new software architecture for analy-sis using the user-oriented design technique.