• IEIE Transactions on Smart Processing and Computing
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• 제4권5호
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• pp.305-310
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• 2015

We propose a new concept for a depth of interaction (DOI) positron emission tomography (PET) detector based on dual-ended-scintillator (DES) readout for small animal imaging. The detector consists of lutetium yttrium orthosilicate (LYSO) arrays coupled with orthogonal wavelength-shifting (WLS) fibre placed on the top and bottom of the arrays. On every other line, crystals that are 2 mm shorter are arranged to create grooves. WLS fibre is inserted into these grooves. This paper describes the design and performance evaluation of this PET detector using Monte Carlo simulations. To investigate sensitivity by crystal size, five types of PET detectors were simulated. Because the proposed detector is composed of crystals with three different lengths, degradation in sensitivity across the field of view was also explored by simulation. In addition, the effect of DOI resolution on image quality was demonstrated. The simulation results proved that the devised PET detector with excellent DOI resolution is helpful for reducing the channels of sensors/electronics and minimizing gamma ray attenuation and scattering while maintaining good detector performance.

• Ocean Systems Engineering
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• 제4권3호
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• pp.201-213
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• 2014

Wave run-up is an important issue in offshore engineering, which is tightly related to the loads on the marine structures. In this study, a series of physical experiments have been performed to investigate the wave run-up around a vertical cylinder in transitional water depth. The wave run-ups of regular waves, irregular waves and focused waves have been presented and the characteristics in frequency domain have been investigated with the FFT and wavelet transform methods. This study focuses on the nonlinear features of the wave run-up and the interaction between the wave run-up and the cylinder. The results show that the nonlinear interaction between the waves and the structures might result wave run-up components of higher frequencies. The wave run-ups of the moderate irregular waves exhibit 2nd order nonlinear characteristics. For the focused waves, the incident waves are of strong nonlinearity and the wavelet coherence analysis reveals that the wave run-up at focal moment contains combined contributions from almost all the frequency components of the focused wave sequence and the contributions of frequency components up to 4th order harmonic levels are recommended to be included.

• 한국전산유체공학회지
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• 제20권4호
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• pp.93-101
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• 2015

This paper provides numerical results of the simulation for the flow around the hull and the propeller of KCS model ship advancing in shallow water conditions. A finite volume method is used to solve the unsteady Reynolds averaged Navier-Stokes(RANS) equations, where the wave-making problem is solved by using a volume-of-fluid(VOF) method. The wave formed near the hull surface in shallow water conditions shows a deep trough dominant pattern that causes the loss of buoyancy followed by hull squat. The flow past the hull increases as the depth of water decreases. However, the axial flow velocity around the stern shows a reduction in magnitude by the effect of shallow water accompanied by the hull-propeller interaction. As a results, the thrust and torque coefficient increase about 8.3% and 6.2%, respectively for a depth of h/T=3.0 corresponding to a depth Froude number of $F_h=0.693$. The resistance coefficient increases about 11.6% at this Froude number condition.

• 아동학회지
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• 제32권5호
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• pp.135-150
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• 2011

The purpose of this study was to examine the interaction strategies used by typically developing boys and girls in their dealings with young children with ADHD in free play situations in inclusive classes. This was done in order to gain an in-depth understanding of the meaning of their interaction strategies. The subjects were 52 typically developing children (comprising 27 boys, 25 girls) and 3 young children with ADHD. The findings were as follows : First, the overall frequency of interaction strategies with the young children with ADHD was greater among the young female children (n = 372) than the young male children (n = 298). Second, when the utterance strategies of the male and female children were sub-categorized, both the male children (79.5%) and the female children (57.0%) mostly made use of avoidance strategies, one of the typical withdrawal strategies. Third, the interaction strategy of control represented 42.0 percent and as such was identified as the most prevalent interaction strategy utilized by the young male children studied. In the case of the young female children, obliging strategies were the most common interaction strategies representing 33.1 percent of the total used. In the light of the findings yielded from this study, some educational recommendations are provided.

• 한국초전도ㆍ저온공학회논문지
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• 제25권1호
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• pp.11-15
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• 2023

In recent years, the interaction force between a permanent magnet and a closed superconductor coil has been gradually investigated in depth. The principle and application potential of an energy storage/convertor composed of a magnet and a closed superconducting coil have been proved. However, the study on the force between a magnet and a non-closed superconducting coil (superconducting roll stack) has hardly been reported in previous literature. The behavior of this kind of interaction and its influence to the interaction force between a permanent and a closed superconducting coil are also still unclear. In this paper, first we investigated the interaction force between a magnet and a superconducting roll stack. Then, a series of experiments were designed and conducted to clarify the factors affected the interaction force, including the geometrical parameters of the superconducting roll stack and the magnetic field density at the roll stack. Moreover, the comparison of the interaction forces between the magnet and roll stack or a closed coil was also introduced.

• Steel and Composite Structures
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• 제48권6호
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• pp.693-708
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• 2023

Composite beams, two materials joined together, have become more common in structural engineering over the past few decades because they have better mechanical and structural properties. The shear connectors between their layers exhibit some deformability with finite stiffness, resulting in interfacial shear slip, a phenomenon known as partial shear interaction. Such a partial shear interaction contributes significantly to the composite beams. To provide precise predictions of the geometric nonlinear behavior shown by two-layered composite beams with interfacial shear slips, a robust analytical model has been developed that incorporates the influence of significant displacements. The application of a higher-order beam theory to the two material layers results in a third-order adjustment of the longitudinal displacement within each layer along the depth of the beam. Deformable shear connectors are employed at the interface to represent the partial shear interaction by means of a sequence of shear connectors that are evenly distributed throughout the beam's length. The Von-Karman theory of large deflection incorporates geometric nonlinearity into the governing equations, which are then solved analytically using the Navier solution technique. Suggested model exhibits a notable level of agreement with published findings, and numerical outputs derived from finite element (FE) model. Large displacement substantially reduces deflection, interfacial shear slip, and stress values. Geometric nonlinearity has a significant impact on beams with larger span-to-depth ratio and a greater degree of shear connector deformability. Potentially, the analytical model can accurately predict the geometric nonlinear responses of composite beams. The model has a high degree of generality, which might aid in the numerical solution of composite beams with varying configurations and shear criteria.

• 한국지반공학회논문집
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• 제18권3호
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• pp.43-50
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• 2002

본 연구에서는 지반말뚝, 말뚝-말뚝캡, 그리고 말뚝-유체간의 상호작용 해석을 수행하여 교각세굴을 고려한 말뚝기초의 거동을 해석하였다. 지반-말뚝의 상호작용은 비선형 하중전이곡선(p-y, t-z, 그리고 q-z 곡선)을, 말뚝-말뚝캡의 상호작용에서는 군말뚝의 배열과 말뚝-말뚝캡 사이의 구속조건을 고려하였다. 말뚝유체의 상호작용은 세굴에 의한 지반의 강성 저하를 고려하여 지반-말뚝의 상호작용에 포함하여 해석하였다. 그 결과 세굴심이 깊어질수록 말뚝에 발생하는 최대 휨모멘트의 값이 증가함을 알 수 있었으며, 이를 바탕으로 세굴에 따른 군말뚝의 안정성 평가에서는 지반-말뚝 및 말뚝-말뚝캡의 상호작용을 고려한 해석을 수행하는 것이 바람직함을 알 수 있었다.

• 방송공학회논문지
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• 제19권1호
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• pp.83-95
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• 2014

최근 손과 손가락을 인식하는 기술은 HCI(human computer interaction)에서 자연스럽고 친숙한 환경을 제공하기 위한 기술로 주목 받고 있다. 본 논문에서는 깊이 카메라를 이용하여 손과 손가락의 모양을 검출 및 인식하는 방법을 제안하고, 그 인식 결과를 활용하여 다양한 기기와 상호연동 할 수 있는 MPEG-U 기반 향상된 사용자 상호작용 인터페이스 시스템을 제안한다. 제안하는 시스템은 깊이 카메라를 이용하여 손을 검출한 후, 손목의 위치를 찾아 최소 손 영역을 검출한다. 이어서 검출된 최소 손 영역으로부터 손가락 끝점을 검출 한 후, 최소 손 영역의 중심점과 손가락 끝점간의 뼈대를 만든다. 이렇게 만든 뼈대의 길이와 인접 뼈대간의 각도차를 분석하여 손가락을 판별한다. 또한, 제안하는 시스템은 사용자가 MPEG-U에서 정의하는 다양한 심벌들을 손 자세로 취하였을 때 제안 방법을 이용하여 손 자세를 인식하고, 인식 결과를 상호연동 가능한 MPEG-U 스키마 구조로 표현한다. 실험에서는 다양한 환경에서 제안하는 손 자세 인식 방법의 성능을 보인다. 또한, 제안 시스템의 상호연동성을 보이기 위해 인식 결과를 MPEG-U part2 표준에 맞는 XML 문서로 표현하고, MPEG-U 참조 소프트웨어를 이용하여 그 표현 결과에 대한 표준 부합성을 검증한다.

• 한국해안해양공학회:학술대회논문집
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• 한국해안해양공학회 2009년도 발표 논문집 제18권
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• pp.164-167
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• 2009

• 한국도로학회논문집
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• 제19권2호
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• pp.1-6
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• 2017

PURPOSES : Pavement textures can be categorized into four according to wavelength: microtexture, macrotexture, megatexture (roads), and roughness. Pavement surface texture influences a number of aspects of tire-pavement interaction such as wet-weather friction, tire-pavement noise, splash, spray, tire-wear, and rolling resistance. In particular, macrotexture is the pavement surface characteristic that considerably impacts tire-pavement noise. In general, it can be demonstrated that tire-pavement noise increases with the increase of texture depth and wavelength. Recently, mean profile depth (MPD) and wavelength have been used to evaluate tire-pavement noise. This study aimed to identify the relationship between mean profile depth and average wavelength for asphalt pavement based on the information obtained on a number of asphalt pavement sections. METHODS : Profile data were collected from a number of expressway sections in Korea. In addition, mean profile depth and average wavelength were calculated by using this profile data. Statistical analysis was performed to determine the correlationship between mean profile depth and average wavelength. RESULTS:This study demonstrates a linear relationship between mean profile depth and average wavelength for asphalt concrete pavement. CONCLUSIONS :The strong relationship between mean profile depth and average wavelength of asphalt pavement was determined in this study.