• Journal of Industrial Technology
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• v.21 no.A
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• pp.167-179
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• 2001

This paper discusses an index-based subsequence matching that supports time warping in large sequence databases. Time warping enables finding sequences with similar patterns even when they are of different lengths. In earlier work, we suggested an efficient method for whole matching under time warping. This method constructs a multidimensional index on a set of feature vectors, which are invariant to time warping, from data sequences. For filtering at feature space, it also applies a lower-bound function, which consistently underestimates the time warping distance as well as satisfies the triangular inequality. In this paper, we incorporate the prefix-querying approach based on sliding windows into the earlier approach. For indexing, we extract a feature vector from every subsequence inside a sliding window and construct a multi-dimensional index using a feature vector as indexing attributes. For query precessing, we perform a series of index searches using the feature vectors of qualifying query prefixes. Our approach provides effective and scalable subsequence matching even with a large volume of a database. We also prove that our approach does not incur false dismissal. To verily the superiority of our method, we perform extensive experiments. The results reseal that our method achieves significant speedup with real-world S&P 500 stock data and with very large synthetic data.

• Design & Manufacturing
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• v.15 no.3
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• pp.32-38
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• 2021

Plate-shaped works are one of the materials that can be applied to the entire industry due to their various shapes and sizes. Plate-shaped parts workpieces are thin and wide, and when processing is completed, they are often bent or deformed in various directions, making it difficult to produce normal products. In particular, this study intends to study the processing deformation and distortion of plate-shaped parts fastened to the jig during milling processing. In this study, a method for preventing deformation occurring in plate-shaped parts was derived through jig element change and CAE analysis, and this was applied to actual processing to produce products with stable dimensions. Through a finite element analysis experiment, it was found that installing two supports on the back of the plate-shaped part results in minimal deformation and the optimal distance between the two supports is 150 mm. Through this experiment, when processing a thin plate product, a support was installed in a direction opposite to the cutting force applied to the thin plate to prevent deformation of the product, thereby improving defects.

• Journal of Korea Multimedia Society
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• v.4 no.5
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• pp.430-438
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• 2001

In this paper, we present the design and implementation of a web-based distance learning system supporting the collaborative browsing. Our system consists of an education affair management system, a video conferencing server/client, a white-board server/client, a session manager and a web browser sharing system. Among other things, our collaborative web browser is unique and not found in any other system. The web browser shows synchronously the same web pages as the lecturer moves through them. Therefore, it allows the student to feel real-time surfing gust as the lecturer would. The session manager supports multi-user and multi-group, and integrates various synchronous collaborative component into one distance learning system by providing the same session data and information of users in a session group. Our collaborative browsing system can increase the efficiency of distance learning and provides the effect of learning in the same classroom by supporting various synchronous functionalities, such as collaborative browsing.

• Proceedings of the Korea Society for Industrial Systems Conference
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• 2000.11a
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• pp.635-645
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• 2000

Within a context of rapid technological change and shifting market conditions, the education environment requires new paradigm of education delivery In accordance of such a technological progress, distance education system, which makes the loaming take place at anytime anywhere, overcoming barriers of time, or distance, is emerging as a mainstream of education delivery replacing the convectional one way delivery system from instructor to learners. This Paper aims to introduce the development principle and algorithm about Instructional System Design(ISD) module, a part of a total solution for distance education services. It was developed on Linux, a free Unix-type operating system. Linux supports so various network protocols, sharing the network resources in a smooth way, that it is able to integrate with other operating system very easily, especially with Windows NT or Windows 2000 servers. In terms of quality, it never falls behind the windows products which are commercially available only, It is a right operating system for the such a school environment that is usually limited in budgets. The development environment of the distance education solution to which ISD module belongs is composing of Apache server for web server, Java bean based on components for ISD module, PHP, server-side scripting language, for HTML documents and MySQL for DBMS.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.6
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• pp.1369-1380
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• 2011

Most existing mobile distance learning systems are asynchronous ones that allow students to download lecture video and presentation material. However, there are a few synchronous real-time mobile distance learning systems that support slide, annotation, feedback from student, and lecture video and audio at the same time. These live mobile distance learning systems have an advantage of supporting real-time interaction between students and a lecturer thereby making students understand the lecture better. But, they also have a disadvantage in the sense that they don't allow students to experience the past lecture. This problem can be solved by recording and replaying lecture session. So far, there are few mobile distance learning systems that support session recording and replay. This paper presents a synchronous mobile distance learning system that supports video and audio, slide with annotation, and real-time feedback from students, as well as session recording and replay, which is not supported by the existing mobile distance learning systems. The evaluation of the system among students shows that 61.3% of them were satisfied while 3.2% weren't.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.6
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• pp.153-158
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• 2016

Broadcasting in multi-hop wireless sensor networks is a basic operation that supports many applications such as route search, setting up addresses and sending messages from the sink to sensor nodes. The broadcasting using flooding causes problems that can be mentioned as a broadcasting storm such as redundancy, contention and collision. A variety of broadcasting schemes using wireless sensor networks have been proposed to achieve superior performance rather than simple flooding scheme. Broadcasting algorithms in wireless sensor networks can be classified into six subcategories: flooding scheme, probabilistic scheme, counter-based scheme, distance-based scheme, location-based schemes, and neighbor knowledge-based scheme. This study analyzes a simple flooding scheme, probabilistic scheme, counter-based scheme, distance-based scheme, and neighbor knowledge-based scheme, and compares the performance and efficiency of each scheme through network simulation.

• Journal of the Korean Society of Safety
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• v.27 no.5
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• pp.99-104
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• 2012

A turnelling work beneath roadways or railways in use is unsafe and dangerous. A turnelling method should be analytically and experimentally studied to verify stability and safety of excavating works by construction step. The conventionally analytical method was ineffective in computational time and cost, so the new analytical method named homogenuity method, was developed and verified compared with analytical results. That method was applied to parameterly study the effect of distance of steel supports and overburdening height of soil. It showed that the homogenuity method was very practical and effective in step-by-step analysis considering construction sequences. A measuring device was set at the construction field and mechanical behavior was monitored during construction. Measuring values are larger than analytical values because impact of inserting steel pipes, lowering level of underground water and vibration of passing vehicles affected soil density during construction, but those values were within allowable limits.

• Korean Journal of Adult Nursing
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• v.28 no.1
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• pp.116-126
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• 2016

Purpose: Lung cancer patients are often stigmatized since lung cancer is closely associated with smoking, which is a self-administered life style. The stigma of lung cancer has been examined in some qualitative studies; however, their findings were diverse and not yet synthesized. Therefore, this meta-synthesis study aimed to explore how lung cancer patients experience stigma. Methods: A meta-synthesis method, as suggested by Sandelowski and Barroso in 2007, was applied by aggregating the findings after an evaluation according to consolidated criteria for reporting qualitative research (COREQ). Results: By synthesizing the findings of the selected seven papers, a synthesized theme was emerged as "experiencing external and internal distances, which mandates authentic and consistent supports." The four sub-themes included 'experiencing some distance from the surrounded world,' 'experiencing self-made distance between the disease and oneself,' 'the disease experience causes social isolation and loneliness,' and 'there is lack of supportive care for myself.' Conclusion: Health care providers should be more attentive to supporting lung cancer patients by providing more effective advocacy programs that improve patients' quality of life.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.9
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• pp.1341-1349
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• 2001

In this paper, 3 D.O.F. actuator, which has three degrees of freedom in one joint, is proposed. The proposed 3 D.O.F. spherical actuator is composed of the rotor and atator. The upper plate of the stator supports the rotor and five electromagnets are located at the base of the stator. The rotor has two permanent magnets, and each rotational axis of the rotor gimbal system is supported by the bearing. To find out the governing equations for the torque generation, Coulombs law and Lorentz force with respect to magnetism is applied. As the experimental results, if the distance between electromagnet and permanent maget is far enough, the force between these magnets can be expressed from current of coils and z-axial distance. For the purpose of control 3 D.O.F. actuator, PID control law is applied. The experimental results are presented to show the validity of the proposed 3 D.O.F. actuator.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.6C
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• pp.434-441
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• 2005

For LDPC decoding, received symbols are splitted bit by bit based using the received in-phase and quadrature components. The method of bit-splitting is affected on decoding performance because its method depend on distance over symbol constellation. Therefore this paper propose the bit split method using the sector information with sacrifice a little performance loss compared to Euclidean distance method. Futhermore DVB-S2 specification supports BC(Backward Compactible) mode which using the hierarchical modulation method, this paper also analyze the decoding performance according to deviation angle of 8PSK constellation for various LDPC coding rates.