• Journal of the Korea institute for structural maintenance and inspection
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• v.28 no.3
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• pp.91-99
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• 2024

Piping systems are crucial facilities used in various industries, particularly in areas related to daily life and safety. Piping systems are fixed to the main structures of buildings and facilities but do not support external loads and serve as non-structural elements performing specific functions. Piping systems are affected by relative displacements owing to phase differences arising from different behaviors between two support points under seismic loads; this can cause damage owing to the displacement-dominant cyclic behavior. Fittings and joints in piping systems are representative elements that are vulnerable to seismic loads. To evaluate the seismic performance and limit states of fittings and joints in piping systems, a high-stroke actuator is required to simulate relative displacements. However, this is challenging because only few facilities can conduct these experiments. Therefore, element-level experiments are required to evaluate the seismic performance and limit states of piping systems connected by fittings and joints. This study proposed a method to evaluate the seismic performance of an elbow specimen that includes fittings and joints that are vulnerable to seismic loads in vertical piping systems. The elbow specimen was created by connecting straight pipes to both ends of a 90° pipe elbow using flexible groove joints. The seismic performance of the elbow specimen was evaluated using a cyclic loading protocol based on deformation angles. To determine the margin of the evaluated seismic performance, the limit states were assessed by applying cyclic loading with a constant amplitude.

• Journal of Intelligence and Information Systems
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• v.16 no.3
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• pp.77-97
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• 2010

Market timing is an investment strategy which is used for obtaining excessive return from financial market. In general, detection of market timing means determining when to buy and sell to get excess return from trading. In many market timing systems, trading rules have been used as an engine to generate signals for trade. On the other hand, some researchers proposed the rough set analysis as a proper tool for market timing because it does not generate a signal for trade when the pattern of the market is uncertain by using the control function. The data for the rough set analysis should be discretized of numeric value because the rough set only accepts categorical data for analysis. Discretization searches for proper "cuts" for numeric data that determine intervals. All values that lie within each interval are transformed into same value. In general, there are four methods for data discretization in rough set analysis including equal frequency scaling, expert's knowledge-based discretization, minimum entropy scaling, and na$\ddot{i}$ve and Boolean reasoning-based discretization. Equal frequency scaling fixes a number of intervals and examines the histogram of each variable, then determines cuts so that approximately the same number of samples fall into each of the intervals. Expert's knowledge-based discretization determines cuts according to knowledge of domain experts through literature review or interview with experts. Minimum entropy scaling implements the algorithm based on recursively partitioning the value set of each variable so that a local measure of entropy is optimized. Na$\ddot{i}$ve and Booleanreasoning-based discretization searches categorical values by using Na$\ddot{i}$ve scaling the data, then finds the optimized dicretization thresholds through Boolean reasoning. Although the rough set analysis is promising for market timing, there is little research on the impact of the various data discretization methods on performance from trading using the rough set analysis. In this study, we compare stock market timing models using rough set analysis with various data discretization methods. The research data used in this study are the KOSPI 200 from May 1996 to October 1998. KOSPI 200 is the underlying index of the KOSPI 200 futures which is the first derivative instrument in the Korean stock market. The KOSPI 200 is a market value weighted index which consists of 200 stocks selected by criteria on liquidity and their status in corresponding industry including manufacturing, construction, communication, electricity and gas, distribution and services, and financing. The total number of samples is 660 trading days. In addition, this study uses popular technical indicators as independent variables. The experimental results show that the most profitable method for the training sample is the na$\ddot{i}$ve and Boolean reasoning but the expert's knowledge-based discretization is the most profitable method for the validation sample. In addition, the expert's knowledge-based discretization produced robust performance for both of training and validation sample. We also compared rough set analysis and decision tree. This study experimented C4.5 for the comparison purpose. The results show that rough set analysis with expert's knowledge-based discretization produced more profitable rules than C4.5.

• The Journal of Korean Society for Radiation Therapy
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• v.24 no.2
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• pp.123-135
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• 2012

Purpose: It is essential to minimize the movement of tumor due to respiratory movement at the time of respiration controlled radiotherapy of non-small cell lung cancer patient. Accordingly, this Study aims to evaluate the usefulness of restricted respiratory period by comparing and analyzing the treatment plans that apply free and restricted respiration period respectively. Materials and Methods: After having conducted training on 9 non-small cell lung cancer patients (tumor n=10) from April to December 2011 by using 'signal monitored-breathing (guided- breathing)' method for the 'free respiratory period' measured on the basis of the regular respiratory period of the patents and 'restricted respiratory period' that was intentionally reduced, total of 10 CT images for each of the respiration phases were acquired by carrying out 4D CT for treatment planning purpose by using RPM and 4-dimensional computed tomography simulator. Visual gross tumor volume (GTV) and internal target volume (ITV) that each of the observer 1 and observer 2 has set were measured and compared on the CT image of each respiratory interval. Moreover, the amplitude of movement of tumor was measured by measuring the center of mass (COM) at the phase of 0% which is the end-inspiration (EI) and at the phase of 50% which is the end-exhalation (EE). In addition, both observers established treatment plan that applied the 2 respiratory periods, and mean dose to normal lung (MDTNL) was compared and analyzed through dose-volume histogram (DVH). Moreover, normal tissue complication probability (NTCP) of the normal lung volume was compared by using dose-volume histogram analysis program (DVH analyzer v.1) and statistical analysis was performed in order to carry out quantitative evaluation of the measured data. Results: As the result of the analysis of the treatment plan that applied the 'restricted respiratory period' of the observer 1 and observer 2, there was reduction rate of 38.75% in the 3-dimensional direction movement of the tumor in comparison to the 'free respiratory period' in the case of the observer 1, while there reduction rate was 41.10% in the case of the observer 2. The results of measurement and comparison of the volumes, GTV and ITV, there was reduction rate of $14.96{\pm}9.44%$ for observer 1 and $19.86{\pm}10.62%$ for observer 2 in the case of GTV, while there was reduction rate of $8.91{\pm}5.91%$ for observer 1 and $15.52{\pm}9.01%$ for observer 2 in the case of ITV. The results of analysis and comparison of MDTNL and NTCP illustrated the reduction rate of MDTNL $3.98{\pm}5.62%$ for observer 1 and $7.62{\pm}10.29%$ for observer 2 in the case of MDTNL, while there was reduction rate of $21.70{\pm}28.27%$ for observer 1 and $37.83{\pm}49.93%$ for observer 2 in the case of NTCP. In addition, the results of analysis of correlation between the resultant values of the 2 observers, while there was significant difference between the observers for the 'free respiratory period', there was no significantly different reduction rates between the observers for 'restricted respiratory period. Conclusion: It was possible to verify the usefulness and appropriateness of 'restricted respiratory period' at the time of respiration controlled radiotherapy on non-small cell lung cancer patient as the treatment plan that applied 'restricted respiratory period' illustrated relative reduction in the evaluation factors in comparison to the 'free respiratory period.

• Journal of Biomedical Engineering Research
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• v.25 no.5
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• pp.391-401
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• 2004

3D imaging systems using 2D phased arrays have a large number of active channels, compelling to use a very expensive and bulky beamforming hardware, and suffer from low volume rate because, in principle, at least one ultrasound transmit-receive event is necessary to construct each scanline. A high speed 3D imaging method using a cross array proposed previously to solve the above limitations can implement fast scanning and dynamic focusing in the lateral direction but suffer from low resolution except at the fixed transmit focusing along the elevational direction. To overcome these limitations, we propose a new real-time volumetric imaging method using a cross array based on the synthetic aperture technique. In the proposed method, ultrasound wave is transmitted successively using each elements of an 1D transmit array transducer, one at a time, which is placed along the elevational direction and for each firing, the returning pulse echoes are received using all elements of an 1D receive array transducer placed along the lateral direction. On receive, by employing the conventional dynamic focusing and synthetic aperture method along lateral and elevational directions, respectively, ultrasound waves can be focused effectively at all imaging points. In addition, in the proposed method, a volume of interest consisting of any required number of slice images, can be constructed with the same number of transmit-receive steps as the total number of transmit array elements. Computer simulation results show that the proposed method can provide the same and greatly improved resolutions in the lateral and elevational directions, respectively, compared with the 3D imaging method using a cross array based on the conventional fixed focusing. In the accompanying paper, we will also propose a new real-time 3D imaging method using a cross array for improving transmit power and elevational spatial resolution, which uses linear wave fronts on transmit.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.3 s.118
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• pp.248-256
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• 2007

In this paper, we propose a selective DFT spreading method to solve a high PAPR problem in uplink OFDMA system. A selective characteristic is added to the DFT spreading, so the DFT spreading method is mixed with SLM method. However, to minimize increment of computational complexity, differently with common SLM method, our proposed method uses only one DFT spreading block. After DFT, several copy branches are generated by multiplying with each different matrix. This matrix is obtained by linear transforming the each phase rotation in front of DFT block. And it has very lower computational complexity than one DFT process. For simulation, we suppose that the 512 point IFFT is used, the number of effective sub-carrier is 300, the number of allowed sub-carrier to each user's is 1/4 and 1/3 and QPSK modulation is used. From the simulation result, when the number of copy branch is 4, our proposed method has more than about 5.2 dB PAPR reduction effect. It is about 1.8 dB better than common DFT spreading method and 0.95 dB better than common SLM which uses 32 copy branches. And also, when the number of copy branch is 2, it is better than SLM using 32 copy branches. From the comparison, the proposed method has 91.79 % lower complexity than SLM using 32 copy branches in similar PAPR reduction performance. So, we can find a very good performance of our proposed method. Also, we can expect the similar performance when all number of sub-carrier is allocated to one user like the OFDM.

• The Journal of the Convergence on Culture Technology
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• v.8 no.2
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• pp.273-280
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• 2022

Based on the MOU between Chosun University and Daegu University, this study was conducted with the aim of exploring the operation strategy of a extracurricular education program on the theme of lifelong education for the disabled in community connection. In front-line university sites, extracurricular education programs are often recognized as forms and procedures to assist in subject learning at the major or liberal arts level, but they have a very important status and identity considering that they are classified as "learning competency reinforcement support", "career psychological counseling support", "employment and start-up support", "subject-linked extracurricular education". Accordingly, the extracurricular education programs has the nature and advantage of covering not only the level of the one-time trend program itself, but also various community -linked problem-solving learning, including students' major learning and employment linkage. As part of the above, this study aims to present a strategy for the operation of a extracurricular education programs with the main theme and content of "lifelong education for the disabled" by viewing Chosun University and Daegu University. The contents of the study were largely presented as "organizational operation strategy between two universities," "operation strategy of curriculum between two universities," and "comprehensive system for extracurricular education programs operation of lifelong education for the disabled between the two universities". First, the first research content, "Organized Operation Strategy between Two Universities," was schematized in detail the process of collaborating and communicating with Chosun University's center of extracurricular activities, Daegu University Lifelong Education Center, and other committees and departments. The second research content, "The Curriculum Operation Strategy between Two Universities", is a detailed schematic diagram of the learning contents, methods, and procedures to be organized in the extracurricular education program. The third study, "Comprehensive System of extracurricular education program Operation for Lifelong Education for the Disabled between Two Universities," presents the results of synthesizing the basis elements essential for operating the extracurricular education program at the level of a roadmap. As a result of the study, it was possible to see the project tasks that could be promoted in-depth through the operation of a extracurricular education program on lifelong education for the disabled through the MOU between the two universities.

• The Korean Journal of Archival Studies
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• no.14
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• pp.3-51
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• 2006

In this paper, I applied known theories of appraisal and re-appraisal to the Japanese Colonial Archives and the Colonial City Planing Archives in Korea. The purpose of this application to some of sample archives was to develop a useful and effective approach to appraise the archives which were not appraised before they were determined to be "permanent" archives by the Japanese colonial officials. The colonial archives have lost their context and "chain of custody." A large portion of their volume also disappeared. Only thirty thousands volumes survived. The appraisal theories and related issues applied to and tested on these archives are; "original natures" of archives defined by Sir. Hillary Jenkinson, Schellenburg's information value appraisal theory, the re-appraisal theory based on economy of preservation and prospect for use of the archives, function-based appraisal theory and documentation theory, the special nature of the archives as unique, old and rare colonial archives, the intrinsic value of the archives, especially the city planing maps and drawings, and finally, the determination of the city planing archives as permanent archives according to the contemporary and modern disposal authority. The colonial archives tested were not naturally self-proven authentic and trustworthy records as many other archives are. They lost their chain of custody and they do not guarantee the authenticity and sincerity of the producers. They need to be examined and reviewed critically before they are used as historical evidence or any material which documented the contemporary society. Rapport's re-appraisal theory simply does not fit into these rare historical archives. The colonial archives have intrinsic values. Though these archives represent some aspects of the colonial society, they can not document the colonial society since they are just survived remains or a little part of the whole archives created. The functions and the structure of the Government General of Korea(朝鮮總督府) were not fully studied yet and hardly can be used to determine the archival values of the archives created in some parts of the colonial apparatus. The actual appraisal methods proved to be effective in the case of colonial archives was Schellenburg's information value appraisal theory. The contextual and content information of the colonial archives were analysed and reconstructed. The appraisal works also resulted in full descriptions of the colonial archives which were never described before in terms of archival principles.

• The Korean Journal of Archival Studies
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• no.80
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• pp.43-88
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• 2024

The National Archives and Records Administration (NARA) is a relatively quiet latecomer to the traditional archives of the Western world. Although the United States lacks a long history of organized public records·archives management, it has developed a modern system optimized for the American historical context. This system focuses on the systematic management and preservation of the vast amount of modern records produced and collected during the tumultuous 20th century. As a result, NARA has established a modern archival system that is optimized for the American historical context. The U.S. public records·archives management system is based on the principle that records·archives are the property of the American people and belong to the public. This concept originated during the British colonial era when records were used to safeguard the rights of the colonies as self-governing citizens. For Americans, records and archives have long been a symbol of the nation's identity, serving as a means of protecting individual freedoms, rights, and democracy throughout the country's history. It is natural, therefore, that American life and history should be documented, and that the recorded past should be managed and preserved for the nation's present and future. The public records·archives management system in the United States is the result of a convergence of theories, practices, lessons learned, and ideas that have been shaped by the country's history, philosophies, and values about records, and its unique experience with records management. This paper traces the origins of records and archives in the United States in a historical context to understand the organic relationship between American life and records. It examines the process of forming a modern public records management system that is both uniquely American and universal to the American context without falling into the two forms of traditions that reflect the uniqueness of American history.

• Sijohaknonchong
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• v.43
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• pp.149-175
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• 2015

There have been few researches about Christian imagination reflected in modern sijo. The purpose of this study was to provide basic information helpful to deeply understand Christian literature and clarify the history of Christian sijo literature. For this purpose, the study focused on pieces of sijo written by Seon Jeong-ju and Jang Sun-ha both of whom put out lots of sijo based on Christian imagination. The two poets are common in that they were born in the Japanese colonial period and started their career as a poet at an almost same time. First of all, how a sijo writer, Seon Jeong-ju applied Christian imagination to his pieces of sijo can be summarized as follows. As a poet and paster, Seon Jeong-ju wrote and published 6 volumes of sijo collection. His pieces of sijo were all written based on Christian imagination. Many of the pieces contain Christianity-related stories that were poetically represented through paradoxical imagination. Among pieces of sijo written by Seon Jeong-ju, some reveal enthusiasm for seeking after truth that he kept in mind as a clergyman and others, the poet's strong belief in the Resurrection. Next, Christian imagination that another sijo writer Jang Sun-ha reflected in his works can be briefed as follows. The poet published a sijo collection of his own in 2010. As one of the best representatives of the modern sijo circles, he is a veteran poet who is still creating pieces of sijo. Since he became a Christian in 1996, he has released more than 200 pieces of Christianity-based sijo including those contained in his sijo collection, "Introduction to Love Studies". Most of the Christian poets quoted words from the Bible or borrowed episodes described in the Book. In those poets, he uses imagination that is allusive to the confession of his faith and, in some cases implies his own views of eschatology. In conclusion, both Seon Jeong-ju and Jang Sun-ha wrote and published lots of sijo works on the basis of Christianity, and each of them built up his own world of Christian sijo. In many of the two poet's pieces of sijo, critical doctrines of Christianity and their desperate devotion to that religion are found. Both of them made remarkable poetic achievements, so they deserve being recognized as second to none in the history of Christian sijo literature.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.5 s.108
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• pp.461-475
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• 2006

In this paper, it is described about the tri-band mobile antenna system design to provide broadband multimedia and direct broadcasting services using goo-stationary Koreasat 3, simultaneously operated in Ka/K/Ku band. The radiating part of the antenna system with a fan beam characteristic in the elevation plane is composed of the quasi-offset dual shaped reflector and the tri-band feeder. The tri-band feeder is also composed of the Ka/K dual band feeder with the protruding dielectric rod, the circular polarizer, the ortho-mode transducer and the circular-polarized Ku band feed array. Especially, the Ka/K dual band circular polarizer was realized firstly using the comb-type structure. For fast satellite-tracking on the movement, the Ku band feed array has the structure of the $2{\times}2$ active phased array which can make electrical beams. And, the circular-polarized characteristic in the feed array was improved by $90^{\circ}$ rotating arrangement of four radiating elements polarized circularly by a $90^{\circ}$ hybrid coupler, respectively. Four beam forming channels to make electrical beams at Ku band are divided into the main beam channel and the tracking beam channel in the output, and noise temperature characteristics of each channel were analyzed on the basis of the contributions of internal sub_units. From the fabricated antenna system, the output power at $P_{1dBc}$ of Ka_Tx channel was measured more than 34.1 dBm and the measured noise figures of K/Ku_Rx channels were less than 2.4 dB and 1.5 dB, respectively, over the operating band. The radiation patterns with co- and cross-polarization in the tri-band were measured using a near-field measurement in the anechoic chamber. Especially, Ku radiation patterns were measured after correcting each initial phase of active channels with partial radiation patterns obtained from the independent excitation of each channel. The antenna gains measured in Ka/K/Ku band of the antenna system were more than 39.6 dBi, 37.5 dBi, 29.6 dBi, respectively. And, the antenna system showed good system performances such as Ka_Tx EIRP more than 43.7 dBW and K/Ku_Rx G/T more than 13.2 dB/K and 7.12 dB/K, respectively.