• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.988-992
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• 2002

Ultrasonic machining technology has been developed over recent years for the manufacture of and quality-assured precision parts for several industrial application such as optics, semiconductors, aerospace, and automobile application. The past decade has seen a tremendous in the use of ceramics in structural application. The excellent thermal, chemical and wear resistance of these material can be realized because of recent improvements in the overall strength and uniformity of advanced ceramics. Ultrasonic machining, in which abrasive particles in slurry with water are presented to the work surface in the presence of an ultrasonic-vibrating tool, is process which should be of considerable interest, as its potential is not limited by the electrical or chemical characteristics of the work material, making it suitable for application to ceramics. This paper intends to further the understanding of the basic mechanism of ultrasonic machining for brittle material and ultrasonic machining of ceramics based in the fracture-mechanic concept has been analyzed.

• Journal of the Korean Statistical Society
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• v.35 no.2
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• pp.167-177
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• 2006

An important role of statistical analysis in science is interpreting observed data as evidence, that is 'what do the data say?'. Although standard statistical methods (hypothesis testing, estimation, confidence intervals) are routinely used for this purpose, the theory behind those methods contains no defined concept of evidence and no answer to the basic question 'when is it correct to say that a given body of data represent evidence supporting one statistical hypothesis against another?' (Royall, 1997). In this article, we use likelihood ratios to measure evidence provided by record values in favor of a hypothesis and against an alternative. This hypothesis is concerned on mean of an exponential model and prediction of future record values.

• Korean Journal of Logic
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• v.13 no.2
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• pp.1-26
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• 2010

The primary purpose of this paper is to examine critically the theory of critical thinking proposed by the late Professor Young-Jung Kim. He defined the basic properties of critical thinking as active reflectivity, and listed deepness, multilaterality and domain-transitivity as primary properties for which critical thinking aims. He, then, pursued how critical thinking can be merged with creativity and proposed the concept 'critico-creative thinking'. I argue that his theory of critical thinking has some limitation, but we can develop his critico-creative thinking further.

• Proceedings of the KSRS Conference
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• 1999.11a
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• pp.43-47
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• 1999

In this paper, we describe the configuration of the KITSAT-3 image data receiving, archiving, processing and distribution system in operation. Following the low-cost and software-based design concept, the whole system is composed of three PCs : two for data receiving, archiving and processing which provide a full dual-redundant configuration and one for image catalog browsing which can be accessed by public users. Except that receiving and archiving PCs have serial data ingest boards plugged in, they are configured by general peripherals. This basic and simple hardware configuration made it possible to show that a very low cost system can support a full ground operation for the utilization of high-resolution satellite image data.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.9
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• pp.860-865
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• 2010

This paper deals with gait assisting rehabilitation robot which helps SCI patient walk again. We propose new concept of orthotic for robot considering motions of Hip and Knee Joints, and how to fit the robot to a user in terms of weight balance and comfortable standing. Then we describe our first engineering sample being designed based on the passive orthotic and show how to make the robot work for SCI patient in basic operation.

• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.767-770
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• 1991

For the control of redundant manipulators, conventional dynamic control methods of local torque optimization showed the instability which resulted in physically unrealizable torque requirements. In this paper, a new dynamic control method which is based on the concept of aspects is proposed. The proposed method starts with the basic understanding of the minors in the Jacobian matrix. It was shown by computer simulations that the proposed method demonstrates a drastic reduction of torque loadings at the joints in the tracking motion of a long trajectory, and thus guarantees the stability of joint torque.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.292-293
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• 2011

We proposed a new power system, Superconducting Power System. The SPS consists of superconducting power cables, fault current limiters, and transformers. The basic concept is to replace 154kV conventional cables with 22.9kV superconducting cables and to convert a 154kV substation into a 22.9kV switching station in downtown area. For the application of the SPS to real power system, it is very important to construct the protection system of the SPS. This study presents a protection system for the new Superconducting Power System (SPS).

• 한국HCI학회:학술대회논문집
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• 2009.02a
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• pp.862-867
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• 2009

The development of internet has changed the realm of life from off-line to on-line, causing not only the overall change in society but also urgently demanding change in the basic concept of museum. Virtual Museums have appeared in line with such changes, and they utilize space regardless of real time and space unlike the traditional museums that collected and preserved works for exhibition in physical space thereby playing a role of catalyst for exhibition in virtual space and for direct exchange with the public. Through relevant literatures and case studies, the present research particularly investigated the exhibition characteristics of virtual reality-based museums out of all types of cyber museum, in an effort to make a comparison with those of offline museums, and eventually to suggest a direction of virtual reality museums that would be established in the future and to consider the possibilities of utilizing them.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.2
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• pp.130-136
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• 2000

Generally, the build-up printed circuit board manufactured by the sequential process with etching, plating, drilling etc. requires many types of equipments and lead time. Etching process is suitable for mass production, however, it is not adequate for manufacturing prototype in the developing stage. In this study, we introduce a screen printing technology to prototyping a build-up printed circuit board. As for the material, photo/thermal curable resin and conductive paste are used for the formation of dielectric and conductor. The build-up structure is made by subsequent processes such as the formation of liquid resin thin layer, the solidification by UV/IR light, and via filling with conductive paste. By use of photo curable resin, productivity is greatly enhanced compared with thermal curable resin. Finally, the basic concept and the possibility of build-up printed circuit board prototyping are proposed in comparison with to the conventional process.

• 유체기계공업학회:학술대회논문집
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• 1998.12a
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• pp.33-41
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• 1998

In this study, the performance prediction programs for centrifugal pumps are developed. To estimate the losses in the centrifugal pump impellers, two-zone model and TEIS(two elements in series) model are applied to the program. The basic concept of two zone model considers the primary zone that is an isentropic core flow and the secondary zone that is non-isentropic region at the impeller exit. The flows through two different zones mixed out at the impeller exit and the mixing process occurs with an increase in entropy, a decrease in total pressure. The level of the core flow diffusion in a impeller was calculated using TEIS(two elements in series) model. The effects of various parameters which are used in this program on the prediction of head and efficiency are discussed. The correlation curves to select the effectiveness of the primitive TEIS model were suggested according to the specific speed of the centrifugal pumps.