• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.7 s.110
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• pp.638-647
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• 2006

Recently, the DFT-Spread OFDM has been studied for the PAPR reduction. However, the DFT-Spread OFDM produces more ICI and SCI problems than OFDM because phase offset mismatch of the DFT spreading code results from the random phase noise in the oscillator. In this paper, at first, phase noise influence on the DFT-Spread OFDM system is theoretically analyzed in terms of the BER performance. Then, the conventional ICI self-cancellation methods are discussed and two kinds of ICI self-cancellation methods are newly proposed. Lastly, a new DFT-Spread OFDM system which selectively adopts the ICI self-cancellation technique is proposed to resolve the interference problem and PAPR reduction simultaneously. Proposednew DFT-Spread OFDM system can minimize performance degradation caused by phase noise, and still maintain the low PAPR property. Among the studied methods, DFT-Spread OFDM with data-conjugate method or newly proposed symmetric data-conjugate method show the significant performance improvements, compared with the DFT-Spread OFDM without ICI self-cancellation schemes. The data-conjugate method is slightly better than symmetric data-conjugate method.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.6
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• pp.115-121
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• 2013

This paper related with the DSE-MMA (Dithered Sign-Error MMA) that is the simplification of computational arithmetic number in blind equalization algorithm in order to compensates the intersymbol interference which occurs the passing the nonlinear communication channel in the presence of the band limit and phase distortion. The SE-MMA algorithm has a merit of H/W implementation for the possible to reduction of computational arithmetic number using the 1 bit quantizer in stead of multiplication in the updating the equalizer tap weight. But it degradates the overall blind equalization algorithm performance by the information loss at the quantization process compare to the MMA. The DSE-MMA which implements the dithered signed-error concepts by using the dither signal before qualtization are added to MMA, then the improved SNR performance which represents the roburstness of equalization algorithm are obtained. It has a concurrently compensation capability of the amplitude and phase distortion due to intersymbol interference like as the SE-MMA and MMA algorithm. The paper uses the equalizer output signal, residual isi, MD, MSE learning curve and SER curve for the performance index of blind equalization algorithm, and the computer simulation were performed in order to compare the SE-MMA and DSE-MMA applying the same performance index. As a result of simulation, the DSE-MMA can improving the roburstness and the value of every performance index after steady state than the SE-MMA, and confirmed that the DSE-MMA has slow convergence speed which meaning the reaching the seady state from initial state of adaptive equalization filter.

• Korean Journal of Comparative Education
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• v.24 no.6
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• pp.163-185
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• 2014

Along with concerns about deteriorating social and economic status of teachers around the world, Master Teacher System(MTS) has been considered as one of the alternatives to transform teaching profession into a more attractive job. In this study, the conditions and problems associated with the MTS in China is analyzed to draw implications for South Korea, which recently legalized the MTS. Research framework including four research questions is developed based on the controversies surrounding MTS of South Korea. The main findings show that the MTS in China was introduced to improve teachers' social and economic status along with the quality of prospective teachers. A very small number of master teachers are selected through rigorous standards including longer service period. They are given additional monetary and non-monetary compensations in return for their teaching-learning leadership and responsibilities. As highly respected educators, they enjoy the lifelong benefits, although they are annually evaluated. It is evident that the MTS has contributed to improving the attractiveness of teaching profession in China. Nevertheless, there are many problems associated with selection standards and methods of master teachers, their roles, compensation, evaluation and terms of service. Recent criticism due to changing circumstances surrounding education in China makes the MTS more questionable. Based on the findings, major implications for future directions of MTS of South Korea are drawn and suggested.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.5
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• pp.231-240
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• 2019

The purpose of this study is to understand of flipped learning of vocational high school teachers and to provide basic data of teacher training program development that can support flipped learning classes of vocational high school. We conducted surveys and focus group interviews to solve these research problems. The focus group interview is conducted on four flipped learning teachers who participated in the questionnaire. The results of this study are as follows. First, vocational high school teachers only heard the term 'flipped learning', but they did not have much experience in class. Second, it is necessary to learn contents and pre-learning for basic understanding of flipped learning, method of making learning contents of learning materials that focused on students' motivation and interest in the classroom. Also, we needed a method to induce participation in classroom activities, and a compensation method and evaluation method to maintain it. In addition, they requested specific flipped learning instruction procedures and various learning materials at each stage in accordance with the vocational high school situation. Third, I requested training contents and practice - centered training method that can induce interest and motivation as the training management method for the vocational high school teachers' flipped learning classes. In addition, it required step - by - step training according to the understanding level of flipped learning of high school teacher.

• Korean Journal of Occupational Therapy
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• v.26 no.4
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• pp.27-41
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• 2018

Objective : This study implemented occupation-based practice as a group program for children with neurodevelopmental disabilities, and investigated the quality of occupational performance, performance and satisfaction, and efficacy levels of the program. Methods : ADOC-S(Aid for Decision making in Occupation Choice-School) and COPM(Canadian Occupational Performance Measure) were used to establish common meaningful occupational goals for 10 children with neurodevelopmental disabilities. After occupational analysis of the 'subway use', the Performance Quality Rating Scale(PQRS) were used to evaluate the quality of occupational performance. Occupation-based interventions were implemented by participants individually performing meaningful occupations in the most natural and real-life environments as possible. The trial consisted of 1 session of pre-intervention assessments, 8 sessions of intervention, where a single session of 100 minutes is provided once a week. Post-intervention evaluation was conducted over one session. Results : The quality of occupational performance by PQRS was 38.10 higher than before intervention. The occupation-based intervention as a group program used the maintain and modify(compensation, adaptation) approaches and acquisition model. In the early stages of intervention (1 to 4 sessions), the occupational performance was greatly improved. The performance level of COPM increased by 5.80 and the satisfaction level was increased by 7.00. In addition, high scores were found in program satisfaction through parental interview. Conclusion : The results of implementing occupation-based interventions to children with neurodevelopmental disabilities showed increase in quality of occupational performance, performance, and satisfaction along with positive effects of satisfaction levels for the program.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.9A
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• pp.1276-1284
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• 1999

We have evaluated the BER's and CLP's of Wireless ATM (WATM) cells employing the concatenated FEC code with pilot symbols for fading compensation through the simulation in indoor wireless channel modeled as a Rayleigh and a Rician fading channel, respectively. The results of the performance evaluation are compared with those obtained by employing the convolutional code in the same condition. In Rayleigh fading channel, considering the maximum tolerance BER ( $10^-3$) as a criterion of the voice service, it is blown that the performance improvement of about 4 dB is obtained in terms of $E_b/N_o$ by employing the concatenated FEC code with pilot symbols rather than the convolutional code with pilot symbols.When the values of K parameter which means the ratio of the direct signal to scattered signal power in Rician fading channel are 6 and 10, it is shown that the performance improvement of about 4 dB and 2 dB is obtained, respectively, in terms of $E_b/N_o$ by employing the concatenated FEC code with pilot symbols considering the maximum tolerance BER of the voice service. Also in Rician fading channel of K=6 and K= 10, considering CLP = $10^-3$ as a criterion, it is observed that the performance improvement of about 3.5 dB and1.5 dB is obtained, respectively, in terms of $E_b/N_o$ by employing the concatenated FEC code with pilot symbols.

• Journal of Navigation and Port Research
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• v.31 no.5 s.121
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• pp.409-414
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• 2007

The effect of multipath is especially serious in urban area and sea surface where buildings and water reflect GPS signal. Multipath brings about the performance degradation on many GPS application because the presence of multipath causes the diminution of pseudorange measurement accuracy in turn position accuracy. In this paper, a multipath mitigation named weighted correlation method is implemented on software GPS receiver, in which the asymmetric correlation function is compensated by modifying the late correlation value. Asymmetry compensation is obtained as weighted sum of two correlators which have different early-late chip spaces. This structure is adopted to lessen the computation load lower keeping up performance similar to that. The performance of implemented multipath mitigation technique is evaluated using GPS signal and multipath signal generated by GPS signal generator and software GPS receiver. The test results show that the weighted correlation method gives hefter performance than the standard correlator and the narrow correlator.

• Journal of the Korean BIBLIA Society for library and Information Science
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• v.33 no.1
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• pp.47-70
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• 2022

The purpose of this study is to empirically verify the factors(organization managerial factors, relational factors and personal factors) that affect the knowledge sharing intention of records management specialists. A total of 126 responses were used for the final analysis and the findings of this study are as follows: First, managers' interests and supports had a significant positive effect on tacit knowledge sharing intention, but evaluation and compensation system had a negative effect on tacit knowledge sharing intention. Second, job stress was found to have a significant positive effect on the intention of knowledge sharing(tacit, explicit). It is required to form an organizational culture where records management specialists can freely participate in knowledge sharing activities with the interest and support of managers. In addition, the process of continuously improving the causes of one of the causes of job stress, such as awareness improvement and deprivation, should be carried out through records management training for all employees. This study is meaningful in that it provides policy implications for promoting knowledge sharing as a solution to the managerial problems faced by records management specialists by utilizing the current staffing structure.

• Journal of the Korean Society of Radiology
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• v.18 no.2
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• pp.153-159
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• 2024

In X-ray projection, Unskilled radiologists become skilled through fail exam. This causes the patient to be exposed to unnecessary radiation. In this study, pre-position unskilled radiologic technologist presented ways to improve clinical proficiency. presented a skull lateral x-ray projection practice method using visual, spatial, and assistive devices. In addition, the accuracy and usefulness of the use of assistive devices were evaluated. When X-ray images were taken based on learning, the rotational spacing, which indicates image distortion, was 7.85 ± 1.45 mm and the tiliting spacing was 4.84 ± 0.5 mm. When practicing using visual aids, the rotational spacing is 4.4 ± 0.76 mm and the inclination spacing is 3.01 ± 0.87 mm. using a spatial compensation device, the rotational spacing is 5.2 ± 0.69 mm and the tiliting spacing is 3.33 ± 0.61 mm. Skull lateral X-ray Image distortion caused by empirical photography practice decreased by 5.4%, but image distortion caused by tilting increased by 1.2%. When practicing using a visual assistive devices, the degree of rotational spacing by 40.1% and the tiliting spacing decreased by 30.7% compared to the empirical x-ray exposure practice. When using spatial assistive devices, the rotation interval was reduced by 41.7% and the tilting interval by 23.7% compared to conventional empirical x-ray exposure practice. Therefore, if an unskilled radiologist practices using visual and spatial aids,the accuracy will be improved in skull lateral x-ray projection.

• Journal of the Korean Society for Library and Information Science
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• v.47 no.3
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• pp.181-205
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• 2013

The purpose of this study is to develop a job-stress scale for librarians who work in university libraries. The study was first conducted by analyzing existing representative job-stress scales that are used domestically and internationally. To understand the characteristic of particular job stress that academic librarians have, the in-depth interview among qualitative research methods was selected, and 15 librarians who work at a 4-year system university libraries participated in this study. Based on the results of the questionnaire survey, the reliability and validity were verified. To analyze the validity, exploratory factor analysis was carried out. To extract factors, principal component analysis was used. To extract factors, principal component analysis was used. For the rotation method, a varimax rotation was applied. A tertiary measurement tool with a total of 46 questions for 11 factors was developed after removing measurement questions that were rejected as a result of the analysis. As a result of factor analysis on the tertiary measurement tool, 11 factors were extracted. Those 11 factors include 'peer relation conflict factor(factor 1)', 'superior-subordinate relation conflict factor (factor 2)', 'work compensation evaluation factor(factor 3)', 'emotional labor factor(factor 4)', 'physical environmental factor(factor 5)', 'employment stability(factor 6)', 'job demand factor(psychological) (factor 7)', 'decision-making and responsibility factor(factor 8)', 'work complexity factor(factor 9)', 'work boundary conflict factor(factor 10)', and 'job demand factor(physical)(factor 11)'.