• Advances in aircraft and spacecraft science
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• 제2권2호
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• pp.217-232
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• 2015

To prevent over-testing of the test-item during random vibration testing Scharton proposed and discussed the force limited random vibration testing (FLVT) in a number of publications. Besides the random vibration specification, the total mass and the turn-over frequency of the load (test item), $C^2$ is a very important parameter for FLVT. A number of computational methods to estimate $C^2$ are described in the literature, i.e., the simple and the complex two degrees of freedom system, STDFS and CTDFS, respectively. The motivation of this work is to evaluate the method for the computation of a realistic value of $C^2$ to perform a representative random vibration test based on force limitation, when the adjacent structure (source) description is more or less unknown. Marchand discussed the formal description of getting $C^2$, using the maximum PSD of the acceleration and maximum PSD of the force, both at the interface between load and source. Stevens presented the coupled systems modal approach (CSMA), where simplified asparagus patch models (parallel-oscillator representation) of load and source are connected, consisting of modal effective masses and the spring stiffness's associated with the natural frequencies. When the random acceleration vibration specification is given the CSMA method is suitable to compute the value of the parameter $C^2$. When no mathematical model of the source can be made available, estimations of the value $C^2$ can be find in literature. In this paper a probabilistic mathematical representation of the unknown source is proposed, such that the asparagus patch model of the source can be approximated. The chosen probabilistic design parameters have a uniform distribution. The computation of the value $C^2$ can be done in conjunction with the CSMA method, knowing the apparent mass of the load and the random acceleration specification at the interface between load and source, respectively. Data of two cases available from literature have been analyzed and discussed to get more knowledge about the applicability of the probabilistic method.

• 패션비즈니스
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• 제20권2호
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• pp.124-133
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• 2016

Currently the fashion industry is developing to create a novel culture due to the very sensitive and knowledge-oriented advancement of the IT industry. With fast turnover of information, consumers have come to have a more diverse desire for purchasing. Cubical expression techniques, which empathizes formativeness, can be a creative expression method adjusting into the trend of this era. Along with functional aspects of consumers, even in a textile manufacturing sector, new materials are required to meet sensitive and emotional aspects. Consumers' desire for new and creative designs and the development and adoption of new materials are essential to meet their emotions. The IT industry and fashion industry are forced to combine and a 3D apparel CAD system has been developed, enabling virtual clothing to be represented within a computer virtual space. All processes such as design, pattern creation, sewing and simulation are possible in 3D level. Digital clothing can shorten the production process time and is very effective in that it can reduce clothing waste generated during the sample production. This paper reviewed the works of Dutch designer, Iris van Herpen, who has developed formative designs. She tries to build, construct, and sculpt employing diversified materials other than soft textile materials, as shown in her series of fashion shows. The materials include films, 3D printed polymers, stiff and sheer organza, and artificial leather textiles. A few characteristics of her works have been selected in order to prepare patterns exhibiting the traits. The paper further focused on the physical features of the textile materials used to express similar techniques and its various forms were reviewed.

• 한국지역지리학회지
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• 제19권1호
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• pp.162-180
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• 2013

본 연구는 최근 긴요해지고 있는 글로벌 시민성교육을 지리 교과와의 관련성의 측면에서 탐색한 것이다. 먼저 글로벌 시민성이라는 개념에 대한 논의와 더불어 이것이 교육적 차원에서 중요하게 된 이유를 세계화라는 시대적 변화와 관련하여 살펴보았다. 둘째, 지리 교과를 통한 글로벌 시민성교육의 정당성에 대한 것으로서 이는 지리 교과의 핵심개념인 장소, 공간, 스케일, 상호의존성의 논의에 토대하여 전개하였다. 그 후 지리 교과를 통한 글로벌 시민성교육을 구조적으로 파악할 수 있도록 하위 영역의 범주를 설정하였는데, 이는 기존의 분류 체계들을 귀납적으로 검토하여 지식과 이해, 기능, 가치와 태도라는 측면에서 재설정한 것이다. 셋째, 글로벌 시민성을 촉진하기 위한 실천적인 측면으로서, 즉 지리수업에 대한 것으로서, 이를 계획하기 위해 사전에 고려해야 할 것들을 목적, 내용, 방법 측면에서 논의하고, 수업 전략을 쟁점 중심 접근과 소비자로서 저항의 지리의 관점에서 살펴보았다. 마지막으로 지리를 통한 글로벌 시민성교육에서 경계해야 할 유의점을 비판적 글로벌 시민성의 관점에서 제시하였다.

• 한국산학기술학회논문지
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• 제12권2호
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• pp.909-919
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• 2011

웹 사이트가 정보와 지식 습득을 위한 일상생활의 필수도구로 인식되면서 정보취약계층을 위한 웹 접근성이 중요시 되고 있다. 특히 2008년 장애인차별금지법의 시행으로 접근성 있는 웹 사이트의 제작이 의무화됨에 따라 웹 접근성 관련 전문 인력의 수요가 더욱 증가하고 있으나, 국내 대학의 정규 교육과정에서 웹 접근성 교육은 이루어지지 않고 있다. 이에 따라 본 논문에서는 타일러 모형과 교수체제 설계기법에 기반을 두고 국내 대학에서 활용 가능한 웹 접근성 교육과정을 개발하였다. 이를 위해 웹 접근성 교육목표를 설정하고, 국내 423개 대학과 국외 4개국의 197개 대학을 대상으로 웹 접근성 관련 교육현황 및 교육내용 구성과 특징을 분석하였다. 이를 바탕으로 웹 접근성 교육 내용을 구성하였고 웹 접근성 전문가 자문을 통해 이의 타당성을 검증하였다. 본 논문은 국내 대학이나 기관에서 웹 접근성 전문 인력 양성을 위한 교육과정의 기초자료로서 활용이 가능하다는 점에서 실무적인 공헌도가 있다.

• Journal of Power Electronics
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• 제17권6호
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• pp.1658-1671
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• 2017

To address the inaccurate load demand sharing problems among parallel inverter-interfaced voltage-controlled distributed generation (DG) units in islanded microgrids (MGs) with different DG power ratings and mismatched feeder impedances, an enhanced voltage control scheme based on the active compensation of circulating voltage drops is proposed in this paper. Using the proposed strategy, reactive power and harmonic currents are shared accurately and proportionally without knowledge of the feeder impedances. Since the proposed local controller consists of two well-separated fundamental and harmonic voltage control branches, the reactive power and harmonic currents can be independently shared without having a remarkable effect on the amplitude or quality of the DGs voltage, even if nonlinear (harmonic) loads are directly connected at the output terminals of the units. In addition, accurate load sharing can also be attained when the plug-and-play performance of DGs and various loading conditions are applied to MGs. The effects of communication failures and latency on the performance of the proposed strategy are also explored. The design process of the proposed control system is presented in detail and comprehensive simulation studies on a three-phase MG are provided to validate the effectiveness of the proposed control method.

• 한국지형학회지
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• 제25권4호
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• pp.37-47
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• 2018

Coastal sand dunes have been regarded as natural defenses to protect hinterland from disasters such as storm surge and typhoons. However, many dunes are not well-deserved in South Korea because of imprudent land development or inappropriate measures after coastal erosion. Lately, beach nourishment and dune reinforcement are emphasized as the effective and environmentally sustainable solution for the coastal protection. They are regarded good strategies to keep landscapes for a time, with little side effects. However, there is little knowledge on the construction methods including proper design and time plans for the best results.In addition, the effects of dune reinforcement in the field should be tested.In thisstudy, we performed sand filling in an eroded dune scarp and surveyed topographic changes in the beach-dune system, which is located along Dasa-ri coast, Chungnam Province, South Korea. Using a network RTK-GPS and drone-based aerial photographs, we analyzed the temporal and spatial changes in the area, before and after the reinforcement. As a result, the dune reinforcement seems to be helpful to mitigates the coastal erosion and to prevent the coastline retreat at least for one year.

• 한국산업정보학회논문지
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• 제14권4호
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• pp.37-48
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• 2009

가정용 서비스 로봇들은 사용자들에게 다양한 시간 추론 서비스들을 제공할 수 있어야 한다. 본 논문에서는 영역-독립적인 인공지능 계획기를 이용하여 이러한 시간 추론 서비스를 효과적으로 구현하는 방법을 제안한다. 영역-독립적인 인공지능 계획기를 이용하여 시간 추론 서비스를 개발하기 위해서는 다양한 실세계 시간 제약들을 어떻게 하나의 계획 영역 정의 언어로 표현하느냐 하는 지식 공학적 문제뿐만 아니라, 인공지능 계획기와 서비스 소비자 사이의 인터페이스를 어떻게 구현하여야 하느냐 하는 시스템 설계 문제를 함께 해결하여야 한다. 본 논문에서는 가정용 서비스 로봇이 고려해야 하는 하나의 예제 시나리오와 전형적인 시간 제약들을 제시하고, 이들을 표준 계획 영역 정의 언어로 표현하는 방법을 제시한다. 또한 본 논문에서는 새로운 시간 추론 서비스를 효율적으로 생성하고 제공하기 위해, 인공지능 계획기를 기초로 하나의 서비스 에이전트를 구현하는 방법에 대해서도 설명한다.

• Nuclear Engineering and Technology
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• 제55권9호
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• pp.3409-3416
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• 2023

Licensing the next-generation of nuclear reactor designs requires extensive use of Modeling and Simulation (M&S) to investigate system response to many operational conditions, identify possible accidental scenarios and predict their evolution to undesirable consequences that are to be prevented or mitigated via the deployment of adequate safety barriers. Deep Learning (DL) and Artificial Intelligence (AI) can support M&S computationally by providing surrogates of the complex multi-physics high-fidelity models used for design. However, DL and AI are, generally, low-fidelity 'black-box' models that do not assure any structure based on physical laws and constraints, and may, thus, lack interpretability and accuracy of the results. This poses limitations on their credibility and doubts about their adoption for the safety assessment and licensing of novel reactor designs. In this regard, Physics Informed Neural Networks (PINNs) are receiving growing attention for their ability to integrate fundamental physics laws and domain knowledge in the neural networks, thus assuring credible generalization capabilities and credible predictions. This paper presents the use of PINNs as surrogate models for accidental scenarios simulation in Nuclear Power Plants (NPPs). A case study of a Loss of Heat Sink (LOHS) accidental scenario in a Nuclear Battery (NB), a unique class of transportable, plug-and-play microreactors, is considered. A PINN is developed and compared with a Deep Neural Network (DNN). The results show the advantages of PINNs in providing accurate solutions, avoiding overfitting, underfitting and intrinsically ensuring physics-consistent results.

• Asia pacific journal of information systems
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• 제29권4호
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• pp.856-874
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• 2019

The performance of recommender systems (RS) has been measured mainly in terms of accuracy. However, there are other aspects of performance that are difficult to understand in terms of accuracy, such as coverage, serendipity, and satisfaction with recommended results. Moreover, particularly with RSs that suggest multiple items at a time, such as YouTube, user satisfaction with recommended results may vary not only depending on their accuracy, but also on their configuration, content, and design displayed to the user. This is true when classifying an RS as a single RS with one recommended result and as a multiple RS with diverse results. No empirical analysis has been conducted on the influence of the content and distribution of recommendation items on user satisfaction. In this study, we propose a research model representing the content and distribution of recommended items and how they affect user satisfaction with the RS. We focus on RSs that recommend multiple items. We performed an empirical analysis involving 149 YouTube users. The results suggest that user satisfaction with recommended results is significantly affected according to the HHI (Herfindahl-Hirschman Index). In addition, satisfaction significantly increased when the recommended item on the top of the list was the same category in terms of content that users were currently watching. Particularly when the purpose of using RS is hedonic, not utilitarian, the results showed greater satisfaction when the number of views of the recommended items was evenly distributed. However, other characteristics of selected content, such as view count and playback time, had relatively less impact on satisfaction with recommended items. To the best of our knowledge, this study is the first to show that the category concentration of items impacts user satisfaction on websites recommending diverse items in different categories using a content-based filtering system, such as YouTube. In addition, our use of the HHI index, which has been extensively used in economics research, to show the distributional characteristics of recommended items, is also unique. The HHI for categories of recommended items was useful in explaining user satisfaction.

• 한국산학기술학회논문지
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• 제18권2호
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• pp.651-659
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• 2017

청소년을 위한 성매개 감염병 교육의 필요성이 증가되고 있지만 대부분의 청소년들은 교과과정의 부족한 시간으로 인하여 제대로 된 교육을 받지 못하고 있다. 이 시기의 성매개 감염병 노출은 증상이 없거나 경미하여 청소년들이 성매개질환에 대한 인지를 못하는 경우가 많아 장기적인 생식기계의 문제를 야기할 수 있다. 스마트폰의 보급과 더불어 청소년들이 정보의 대부분을 스마트폰을 통하여 얻고 있어 스마트폰을 활용한 교육이 청소년에서 효과적이다. 청소년의 성 매개 감염병 지식을 향상시키기 위한 교육의 방법으로 딕 앤 케리의 체계적인 교수 설계 모델을 적용하여 성 매개 감염병 교육 스마트폰 어플리케이션 개발을 하였다. 본 연구는 이 스마트폰 어플리케이션 개발 전략 및 개발 과정을 기술하였다. 이 스마폰 어플리케이션은 6명의 전문가들과 함께 개발되었으며 교육 내용은 청소년들이 이해하기 쉬운 용어를 사용하였다. 학습능력 향상을 위한 주요 전략으로는 만화로 된 교육내용, 비밀 문의와 질의응답 기능, 버튼 색 변화 및 반복 학습기능 수록 등이다. 본 연구에서 개발된 스마트폰 어플리케이션은 학교, 청소년 관련 기관 및 병원에서 청소년들의 성매개 감염병 지식, 성매개 감염병 예방 및 성매개 감염병 대처 능력을 향상 시키는데 활용 될 수 있다.