• Journal of Navigation and Port Research
• /
• v.48 no.3
• /
• pp.155-163
• /
• 2024

As the demand for reducing carbon emissions increases, efforts to reduce the usage of fossil fuels and research on renewable energy are also increasing. Among the various renewable energy harvesting techniques, the floating offshore wind turbine has several advantages. Compared to other technologies, it has fewer installation limitations due to interference with human activity. Additionally, a large wind turbine farm can be constructed in the open ocean. Therefore, it is important to conduct motion analysis of floating offshore wind turbines in waves during the initial stage of conceptual design. In this study, a frequency motion analysis was conducted on a semi-submersible type floating offshore wind turbine. The analysis focused on the effects of varying trim on the motion characteristics. Specifically, motion response analysis was performed on heave, roll, and pitch. Natural period analysis confirmed that changing the trim angle did not significantly affect the heave and pitch motions, but it did have a regular impact on the roll motion.

• Tunnel and Underground Space
• /
• v.24 no.5
• /
• pp.354-365
• /
• 2014

The horizontal response spectra using the observed ground motions from 15 Fukuoka earthquake series, including main earthquake (2005/03/20; Mw=6.5), were analysed and then were compared to both the seismic design response spectra (Regulatory Guide 1.60), applied to the domestic nuclear power plants, and the Korean Standard Design Response Spectrum for general structures and buildings (1997). 178 horizontal ground motions, without considering soil types, were used for normalization with respect to the peak acceleration value of each ground motion. The results showed that response spectrum have strong dependency on epicentral distance. The results also showed that the horizontal response spectra revealed higher values for frequency bands at two frequency bands (about 8 - 10 and 16- 20 Hz) than Regulatory Guide 1.60. The results were also compared to the Korean Standard Building Design Spectrum for the 3 different soil types and showed that thehorizontal response spectra revealed higher values for almost all period bands than the Korean Standard Response Spectrum (500 yrs; Return Period; Seismic province 1; SE soil conditions). Through the qualitative improvements and quantitative enhancement of the observed ground motions, the diversity of the observed ground motions should be considered more significantly to improve the certainty of response spectrum.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.18 no.1
• /
• pp.709-714
• /
• 2017

Structures like bridges or buildings need to be checked continuously to diagnose their safety. However, it is extremely difficult for the people who access such structures to check all areas directly. To overcome this problem, there is a lot of active research into structural health monitoring (SHM) with wireless sensor nodes (WSNs). In this paper, for more accurate checking of SHM with WSNs, we experimentally compare and evaluate the performance of Xenomai, which provides real-time processing under the traditional Linux kernel. For this purpose, we patch Xenomai into the traditional Linux kernel of a commercial embedded board, Raspberry Pi, and implement a task that periodically reads vibration data of the z-axis from an accelerometer in order to analyze the natural frequency of cantilever beams. Reading the data from the traditional Linux kernel with the same method, we analyze the natural frequency of the cantilever beams using Smart Office Analyzer. Finally, to review the validity of Xenomai for WSNs, we obtain vibration data on the z-axis from the accelerometer via wired network and compared and analyzed them the same way.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.4 no.4
• /
• pp.319-332
• /
• 2002

Domestic masonry railroad tunnel lining consists of red bricks or granite stone blocks and mortar. It is necessary to evaluate the behaviour of the masonry tunnel lining during an earthquake because the lining was constructed without the consideration of seismic loads. In this study, a methodology to evaluate the seismic resistant capacity of masonry tunnel linings was proposed, i.e. material property evaluation and seismic analysis technique. The red brick masonry tunnel lining is arrayed with multi-layers composed of 3 to 5 bricks depending on ground conditions and each brick is attached with mortar. Equivalent property concept was adopted to consider the stiffness difference among the red brick material itself and joints between bricks. Response spectrum analysis was performed by considering ground-structure interactions. A parametric study was performed to figure out the effect of relative stiffness between the lining and rock mass on the seismic behavior. A resonable countermeasure to minimize the earthquake-induced damage was also proposed.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.16 no.1
• /
• pp.291-299
• /
• 2016

This paper raises a question of whether a simple periodic phenomenon is associated with the topology and provides the convincing answers to it. A variety of music instrumental sound signals are used to prove our assertion, which are embedded in Euclidean space to analyze their topologies by computing the homology groups. A commute time embedding is employed to transform segments of waveforms into the corresponding geometries, which is implemented by organizing patches according to the graph-based metric. It is shown that commute time embedding generates the intrinsic topological complexities although their geometries are varied according to the spectrums of the signals. This paper employs a persistent homology to determine the topological invariants of the simplicial complexes constructed by randomly sampling the commute time embedding of the waveforms, and discusses their applications.

• The Journal of Bigdata
• /
• v.2 no.2
• /
• pp.33-46
• /
• 2017

Service part has the attribute causing a difficulty of the systematic management like a kind of diversity, uncertainty of demand, high request for quick response against general complete product. Especially, order picking is recognized as the most important work in the warehouse of the parts since inbound cycle of the service part long but outbound cycle is relatively short. But, increasing work efficiency in the warehouse has a limitation that cycle, frequency and quantity for the outbound request depend on the inherent features of the part. Through this research, not only are the types of the parts classified with the various and specified data but also the method is presented that it minimizes (that) the whole distances of the order picking and store location about both inbound and outbound by developing the model of the demand prediction. Based on this study, I expect that all of the work efficiency and the space utilization will be improved without a change of the inbound and outbound quantity in the warehouse.

• Korean Journal of Adult Nursing
• /
• v.14 no.4
• /
• pp.612-624
• /
• 2002

연구목적: 이 연구는 한국의 전통적 문화에 기초한 한국적 간호이론 개발을 위하여 고전문헌과 관련문헌으로부터 한국인의 세계관을 도출함을 목적으로 한다. 연구방법: 한국인의 세계관 도출을 위하여 문헌분석방법을 적용하였다. 연구자료는 조선왕조 500년과 현대까지 한국인의 사상체계에 가장 큰 영향을 끼친 성리학의 근간을 이루는 태극도설과 역경을 중심으로 한 고전문헌과 관련 해설서들로 하였다. 연구결과: 한국인의 세계관의 원리로서 변화의 원리, 통일성의 원리, 인본주의 원리를 도출하였다. 그들 각각의 하위개념으로 1) 변화의 원리에는 생산성, 주기성, 중용, 2) 통일성의 원리에는 유기적 체계, 동시성, 전일주의, 조화, 그리고 3) 인본주의 원리에는 경(敬), 충(忠), 서(恕), 효(孝)을 도출하였다. 결론: 서양의 간호개념이 아닌 한국인의 세계관의 원리와 하위개념을 기초로 한국인의 고유한 건강과 간호개념을 도출함으로서 한국적 간호이론개발에 기여할 수 있다.

• 한국IT서비스학회:학술대회논문집
• /
• 2009.05a
• /
• pp.255-259
• /
• 2009

해외시장 진출이 가능한 국내 고유노형 개발을 목표로 지난 '07년 8월부터 APR+(Advanced Power Reactor Plus)기술개발 사업이 추진 중에 있다. 본 사업을 통하여 생산 되는 원전 설계 결과물들을 기존의 파일 기반 관리 시스템에서 진일보한 데이터 기반 관리시스템을 개발하여 관리하고자 한다. 본 시스템은 원자력 발전소 전 수명주기 동안 데이터 간의 유기적 연계 사용을 목표로 하고 국제표준을 사용하여 개방형 시스템으로 구축한다. 본 연구는 APR+ 설계정보관리시스템 구축을 위한 기반연구로써 국제표준 기술 및 원자력 발전 분야의 정보관리 사례 등을 분석하여 시스템 개발 방향을 전망하고자 한다.

• Proceedings of the Korean Information Science Society Conference
• /
• 2004.10c
• /
• pp.619-621
• /
• 2004

ARP는 IP 네트워크 상에서 IP 주소를 물리적 네트워크 주소로 대응시키기 위해 사용되는 프로토콜이다. 네트워크에서 데이터를 전송할 때는 컴퓨터간의 물리적 주소를 이용하여 전승하는데 이 물리적 주소는 각각의 랜카드마다 고유하게 갖는 값으로 네트워크에서는 실제로 데이터를 전달할 때 네트워크 카드가 가진 물리적 주소를 이용하여 전달 하지만 소프트웨어 차원에서는 IP 주소라는 것을 사용한다. ARP 프로토콜은 IP 주소를 실질적인 네트워크 어댑터의 물리적 주소와 연관시킬 때 사용되는 것이다. 본 논문에서는 ARP 동보 패킷을 이용한 네트워크 강시 대상 노드들의 정보를 자동적으로 구축하는 기능을 갖는 네트워크 모니터링 시스템을 설계하고 구현한다. 본 네트워크 모니터링 시스템은 ARP 동보 패킷을 분석하여 네트워크 감시 대상 노드들을 인식하고 NETBIOS 모듈을 이용한 노드 이름 확인과 Ping 모듈을 이용한 노드 상태 및 정보를 표시하며 주기적인 업데이트를 통해 노드 정보를 표시하는 기능을 갖는다.

• Electronics and Telecommunications Trends
• /
• v.23 no.5
• /
• pp.89-98
• /
• 2008

칼코지나이드 소재는 주기율표 6족의 칼코젠 원소로 구성되는 이원계 이상의 화합물 반도체 이자 반금속으로 분류되는 소재이다. 칼코지나이드 소재는 상변화 특성 및 광변전환 특성으로 광 및 전기 메모리, 의료기기 및 광소자 등에 사용되고 있다. 최근 빠른 스위칭 특성 및 용액증착법으로 재료개발이 가능해짐에 따라 차세대 원천소재로 평가되어 전세계적으로 급격한 연구가 이루어지고 있으며 고유가로 인한 신재생에너지 등으로 활용분야가 확대되고 있다. 본 고에서는 칼코지나이드 소재의 핵심기술 및 특성, 주요기관의 최근 칼코지나이드 소재개발 동향, 연구개발 동향 및 발전전망에 대해 살펴보기로 한다.