• The Transactions of the Korean Institute of Power Electronics
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• v.27 no.1
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• pp.9-17
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• 2022

The series-connected semiconductor devices structure is one way to achieve a high voltage rating. However, a problem with voltage imbalance exists in which different voltages are applied to the series-connected switches. This paper proposed a new voltage balancing technique that controls the turn-off delay time of the switch by adding one bipolar junction transistor to the gate turn-off path. The validity of the proposed method is proved through simulation and experiment. The proposed active gate driver not only enables voltage balancing across a variety of current ranges but also has a greater voltage balancing performance compared with conventional RC snubber methods.

• Journal of KIEE
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• v.10 no.1
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• pp.29-34
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• 2000

In this paper, a design method of a controller is presented for a class of nonlinear systems which have time-varying parametric uncertainly. Some features of this controller are that it can tackle 1) nonlinear parametrization(i.e. uncertain parameters enter the system in the nonlinear form) and 2) nonvanishing peturbation (i.e. uncertainty need not vanish at the origin). The class of systems considered in this paper has the triangular structure for which the well-known backstepping design can be applied. The uncertain parameter is assumed to be contained in the bounded set whose size can be arbitrarily large. Also, the uncertain system are globally uniformly bounded and converge to a compact set whose size is designable. In particular, the first state of the system can be made arbitrarily small, which can be seen by the presented simulation result.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.05a
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• pp.153-154
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• 2021

Currently, the construction industry is decreasing every year due to people's poor perception, high labor intensity, unstable employment structure, and welfare problems, as people avoid entry. Accordingly, this study investigated how to attract trainees and graduates from domestic construction education institutions to the construction industry. If institutional devices are prepared to prepare for the future by improving the welfare system such as unemployment benefits and retirement deductions in the construction industry, many trainees in their 20s and 30s will be attracted to the construction industry. If it helps expand hands-on education through on-site linkage and has the necessary technical skills for practice, it is believed that trainees and graduates in their 4s and 60s will be attracted to the construction industry.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.05a
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• pp.55-58
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• 2021

PFCM-R 알고리즘을 적용한 기존의 반려견 진단 방법에서는 클러스터링에서 사용되는 파라미터 값을 경험적으로 설정하고 견주가 입력하는 증상들 사이에서 관련성이 낮은 증상이 필터링 되지 않아서 질병의 도출 성능을 저하시키는 원인이 된다. 따라서 본 논문에서는 노드 활성 함수를 적용하여 증상간의 관련성이 적은 증상 데이터를 제거하여 학습 데이터를 구성한 후, 연상 메모리 알고리즘에 적용하여 반려견의 질병에 대한 진단 성능을 개선시키는 하이브리드 기반 다층 학습 구조를 제안하여 반려견 진단에 적용한다. 기존의 PFCM-R 알고리즘 진단 방법과 제안된 하이브리드 다층 구조 진단 방법을 비교분석한 결과, 기존의 방법보다 제안된 방법이 입력된 증상들에 대해서 기존의 방법보다 관련성이 있는 질병 도출 성능이 23.7%가 개선되었다.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.11a
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• pp.146-147
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• 2021

In this study, the deterioration of concrete subjected to high temperature was evaluated using harmonics. When concrete is exposed to high temperatures, its mechanical properties deteriorate. In order to evaluate this deterioration, a method of analyzing the waveform of elastic waves was applied. As the heating temperature increased, the fundamental wave of the 50 kHz elastic wave passing through the concrete decreased. In addition, harmonics were generated at each temperature, and the higher the heating temperature, the greater the ratio of harmonics. The higher the compressive strength, the greater the amplitude of the fundamental wave, and this phenomenon is thought to be due to the internal structure of concrete.

• The Bulletin of The Korean Astronomical Society
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• v.45 no.1
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• pp.60.1-60.1
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• 2020

We present optical variability of nearby luminous active galactic nucleus (AGN). We use the multi-epoch data of 46 AGNs obtained from 2015 to 2019 through SNU AGN Monitoring Project (SAMP), which was carried out for the reverberation mapping of luminous AGNs. We estimated variability amplitudes and time scales using the various types of analytic function, such as structure function and damped random work. We present the comparisons between physical properties of AGNs and optical variability in order to unveil the origin of the variability of AGNs.

• International conference on construction engineering and project management
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• 2015.10a
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• pp.501-502
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• 2015

Construction Standard Specifications, part of contract documents, has been improved through various amendments since their first enactment in 1967 up to the latest 2013 version. However, complaints about inconvenience and low availability have been continuously made in their structure and contents. Therefore, an improvement is needed based on the experts' opinions both from industrial and academic fields. This basic study is to compare the Korean specifications to those from the developed countries and derive the suggestions on their improvement. Furthermore, it aims to delve into the experts' opinion on the subject and identify the direction and priority for the improvement of the specifications. Through this study, user friendliness and efficiency are expected to be obtained in using the specifications.

• SUVANNABHUMI
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• v.6 no.1
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• pp.137-160
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• 2014

This study explores postmodernism in Vietnamese literature. While there has been much dispute among critics regarding postmodernism in Vietnamese literature, postmodernism is now thought to be something that cannot be denied. Vietnamese postmodernism has Vietnamese characteristics and is strongly influenced by American literature. The structure of some Vietnamese short stories is similar to that of some American writers. In the writings of Jean-François Lyotard, Jean Baudrillard and Ihab Hassan, for example, we find out many characteristics which are ascribed to postmodern Vietnamese literature. We propose the use of the term 'Lao Tzu discourse'which is to include the main concepts of postmodernism such as chaos, nothingness and fragmentation. We propose that postmodern Vietnamese Literature appeared in the 1940s with the collection, Fall Spring Poems (1942), and is also seen with the prose of Nguyen Khai and Nguyen Minh Chau in the 1980s, and the drama written by Luu Quang Vu in the 1980s. There now exists a large group of postmodern Vietnamese writers, like Le Dat, Thanh Thao, Bao Ninh, Cao Duy Son, Nguyen Ngoc Tu and Nguyen Binh Phuong, among others.

• East Asian mathematical journal
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• v.39 no.4
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• pp.437-454
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• 2023

The core of the change in the era of the 4th industrial revolution is the change in the base of 'digital technology'. These changes are incomparably large and are expected to have a more important impact on our lives than ever before. One of the major inflection points in the transition to the digital era is the education field, and IT technology has become an essential element in the educational field. Accordingly, this study examines domestic research trends related to the educational environment based on digital technology. Then, we would like to provide implications for the establishment of a digital-based educational environment that will change in the future. To this end, Semantic network analysis has been conducted to quantitatively structure text data obtained from studies related to digital technology in the field of mathematics education over the past 10 years, and the discussion will continue based on the results.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.18 no.4
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• pp.1122-1140
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• 2024

The importance of indoor positioning has grown in numerous application areas such as emergency response, logistics, and industrial automation. In ships, indoor positioning is also needed to provide services to passengers on board. Due to the complex structure and dynamic nature of ship environments, conventional positioning techniques have limitations in providing accurate positions. Compared to other indoor positioning technologies, Bluetooth 5.1-based indoor positioning technology is highly suitable for ship environments. Bluetooth 5.1 attains centimeter-level positioning accuracy by collecting In-phase and Quadrature (IQ) samples from wireless signals. However, distorted IQ samples can lead to significant errors in the final estimated position. Therefore, we propose an indoor positioning method for ships that utilizes a Deep Neural Network (DNN) combined with IQ fingerprint maps to overcome the challenges associated with accurate location detection within the ship. The results indicate that the accuracy of our proposed method can reach up to 97.76%.