• 제목/요약/키워드: linear series

검색결과 1,279건 처리시간 0.026초

보간법을 이용한 옥타브 밴드폭 음향 하중 SPL의 시계열 데이터 생성 (Generation of Time Series Data from Octave Bandwidth SPL of Acoustic Loading Using Interpolation Method)

  • 고은수;김인걸;전민혁;조현준;박재상;김민성
    • 한국군사과학기술학회지
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    • 제24권1호
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    • pp.1-11
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    • 2021
  • Thermal protection system structures such as double-panel structures are used on the skin of the fuselage and wings to prevent the transfer of high heat into the interior of an high supersonic/hypersonic aircraft. The thin-walled double-panel skin can be exposed to acoustic loads by high power engine noise and jet flow noise, which can cause sonic fatigue damage. In order to predict the fatigue life of the skin, the octave bandwidth SPL should be calculated as narrow bandwidth PSD or acoustic load history using interpolation method. In this paper, a method of converting the octave bandwidth SPL acoustic load into a narrow bandwidth PSD and reconstructed acoustic load history was investigated. The octave bandwidth SPL was converted to the narrow bandwidth PSD using various interpolation methods such as flat, log and linear scale, and the probabilistic characteristics and fatigue damage results were compared. It was found that average error of fatigue damage index by the log scale interpolation method was relatively small among three methods.

선택의 상호작용성과 성찰의 상호미디어성: <블랙미러: 밴더스내치>를 중심으로 (Selective Interactivity and Reflexive Intermediality: Focusing on the Neflix Film )

  • 김무규
    • 한국콘텐츠학회논문지
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    • 제21권8호
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    • pp.60-68
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    • 2021
  • 본 논문의 목적은 2018년부터 넷플릭스에서 상영된 <블랙 미러: 밴더스내치>의 형식적 특성에 대해 알아보고 그것의 의미를 해석하는 것이다. 이 콘텐츠는 시청자에게 사건 진행을 선택할 수 있도록 하고 이에 따라 각기 다른 결말이 나타나기 때문에 일종의 상호작용적 서사로 볼 수 있다. 그러나 여러 가지 방식으로 상호작용이 제한되는 경우도 있어서 수용자는 선택의 자유를 충분히 누리지 못한다. 또한 여러 결말에서 공통적으로 <블랙 미러> 시리즈에 전형적인 테크놀로지 비판의 주제가 나타나는데, 그래서 <밴더스내치>를 전통적 서사의 일종으로 간주할 수도 있다. 이러한 이중적인 서사의 상황 때문에 사용자의 선택 가능성과 작가의 서사적 권위는 충돌하게 된다. 그리고 그 충돌로 말미암아 복잡한 형식이 발생하는데, 그것은 비선형적 상호작용성과 선형적 서사 형식 사이의 중간적인 것이며, 혹은 두 가지가 융합된 결과이다. 그리고 그것을 메타렙시스 또는 제4의 벽을 파기하는 형식과 같은 자기반영의 형식으로 이해할 수 있다. 본 논문에서는 이러한 특수한 형식을 통해 성찰적 상호미디어성, 즉 일종의 융합 형식을 통한 미디어의 자기성찰이 이루어질 수 있음을 설명해 보고자 한다.

A Study of 100 tonf Tensile Load for SMART Mooring Line Monitoring System Considering Polymer Fiber Creep Characteristics

  • Chung, Joseph Chul;Lee, Michael Myung-Sub;Kang, Sung Ho
    • 한국해양공학회지
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    • 제35권4호
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    • pp.266-272
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    • 2021
  • Mooring systems are among the most important elements employed to control the motion of floating offshore structures on the sea. Considering the use of polymer material, a new method is proposed to address the creep characteristics rather than the method of using a tension load cell for measuring the tension of the mooring line. This study uses a synthetic mooring rope made from a polymer material, which usually consists of three parts: center, eye, and splice, and which makes a joint for two successive ropes. We integrate the optical sensor into the synthetic mooring ropes to measure the rope tension. The different structure of the mooring line in the longitudinal direction can be used to measure the loads with the entire mooring configuration in series, which can be defined as SMART (Smart Mooring and Riser Truncation) mooring. To determine the characteristics of the basic SMART mooring, a SMART mooring with a diameter of 3 mm made of three different polymer materials is observed to change the wavelength that responds as the length changes. By performing the longitudinal tension experiment using three different SMART moorings, it was confirmed that there were linear wavelength changes in the response characteristics of the 3-mm-diameter SMART moorings. A 54-mm-diameter SMART mooring is produced to measure the response of longitudinal tension on the center, eye, and splice of the mooring, and a longitudinal tension of 100 t in step-by-step applied for the Maintained Test and Fatigue Cycle Test is conducted. By performing a longitudinal tension experiment, wavelength changes were detected in the center, eye, and splice position of the SMART moorings. The results obtained from each part of the installed sensors indicated a different strain measurement depending on the position of the SMART moorings. The variation of the strain measurement with the position was more than twice the result of the difference measurement, while the applied external load increased step-by-step. It appears that there is a correlation with an externally generated longitudinal tensional force depending on the cross-sectional area of each part of the SMART mooring.

비선형 해양파 수치 모사를 위한 고속 재현 기법 (A fast reconstruction technique for nonlinear ocean wave simulation)

  • 이상범;최영명
    • 융합신호처리학회논문지
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    • 제23권1호
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    • pp.15-20
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    • 2022
  • 최근 컴퓨터 성능 향상과 더불어 대규모 클러스터 서비스가 기존의 산업 및 연구기관뿐만 개인에게도 제공되고 있으며, 막대한 계산 성능을 이용한 공학 설계 활용은 빠르게 증가하고 있다. 이에 조선 해양 산업에서는 많은 계산 비용이 요구되는 전산유체역학 기법을 선박 및 해양구조물 설계에 활용하려는 노력이 증가하고 있다. 선박 및 해양구조물과 같은 부유체는 대양에서 해양파, 조류, 바람과 같은 환경 외란에 노출되어 있으며 이러한 환경 외란은 전산유체역학에서 고정도 모델링이 필요하다. 특히 해양파의 경우 비선형 전산유체역학의 특성상 기존의 선형 중첩법에서 벗어난 비선형 해양파가 고려되어야 한다. 본 연구에서는 이러한 비선형 해양파 수치 모사를 위해 고속 재현 기법을 제안하고 전산유체역학 기법을 활용하여 검증을 수행하였다.

Free vibration analysis of FG plates under thermal environment via a simple 4-unknown HSDT

  • Attia, Amina;Berrabah, Amina Tahar;Bousahla, Abdelmoumen Anis;Bourada, Fouad;Tounsi, Abdelouahed;Mahmoud, S.R.
    • Steel and Composite Structures
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    • 제41권6호
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    • pp.899-910
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    • 2021
  • A 4-unknown shear deformation theory is applied to investigate the vibration of functionally graded plates under thermal environment. The plate is fabricated from a functionally graded material mixed of ceramic and metal with continuously varying material properties through the plate thickness. Three types of thermal loadings, uniform, linear and nonlinear temperature rises along the plate thickness are taken into account. The present theory contains four unknown functions as against five or more in other higher order shear deformation theories. The through-the-thickness distributions of transverse shear stresses of the plate are considered to vary parabolically and vanish at upper and lower surfaces. The present model does not require any problem dependent shear correction factor. Analytical solutions for the free vibration analysis are derived based on Fourier series that satisfy the boundary conditions (Navier's method). Benchmark solutions are firstly considered to evaluate the accuracy of the proposed model. Comparisons with the solutions available in literature revealed the good capabilities of the present model for the simulations of vibration responses of FG plates. Some parametric studies are carried out for the frequency analysis by varying the volume fraction profile and the temperature distribution across the plate thickness.

Prediction of pollution loads in agricultural reservoirs using LSTM algorithm: case study of reservoirs in Nonsan City

  • Heesung Lim;Hyunuk An;Gyeongsuk Choi;Jaenam Lee;Jongwon Do
    • 농업과학연구
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    • 제49권2호
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    • pp.193-202
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    • 2022
  • The recurrent neural network (RNN) algorithm has been widely used in water-related research areas, such as water level predictions and water quality predictions, due to its excellent time series learning capabilities. However, studies on water quality predictions using RNN algorithms are limited because of the scarcity of water quality data. Therefore, most previous studies related to water quality predictions were based on monthly predictions. In this study, the quality of the water in a reservoir in Nonsan, Chungcheongnam-do Republic of Korea was predicted using the RNN-LSTM algorithm. The study was conducted after constructing data that could then be, linearly interpolated as daily data. In this study, we attempt to predict the water quality on the 7th, 15th, 30th, 45th and 60th days instead of making daily predictions of water quality factors. For daily predictions, linear interpolated daily water quality data and daily weather data (rainfall, average temperature, and average wind speed) were used. The results of predicting water quality concentrations (chemical oxygen demand [COD], dissolved oxygen [DO], suspended solid [SS], total nitrogen [T-N], total phosphorus [TP]) through the LSTM algorithm indicated that the predictive value was high on the 7th and 15th days. In the 30th day predictions, the COD and DO items showed R2 that exceeded 0.6 at all points, whereas the SS, T-N, and T-P items showed differences depending on the factor being assessed. In the 45th day predictions, it was found that the accuracy of all water quality predictions except for the DO item was sharply lowered.

Centrifuge modeling of dynamically penetrating anchors in sand and clay

  • An, Xiaoyu;Wang, Fei;Liang, Chao;Liu, Run
    • Geomechanics and Engineering
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    • 제30권6호
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    • pp.539-549
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    • 2022
  • Accidental anchor drop can cause disturbances to seabed materials and pose significant threats to the safety and serviceability of submarine structures such as pipelines. In this study, a series of anchor drop tests was carried out to investigate the penetration mechanism of a Hall anchor in sand and clay. A special anchor drop apparatus was designed to model the inflight drop of a Hall anchor. Results indicate that Coriolis acceleration was the primary cause of large horizontal offsets in sand, and earth gravity had negligible impact on the lateral movement of dropped anchors. The indued final horizontal offset was shown to increase with the elevated drop height of an anchor, and the existence of water can slow down the landing velocity of an anchor. It is also observed that water conditions had a significant effect on the influence zone caused by anchors. The vertical influence depth was over 5 m, and the influence radius was more than 3 m if the anchor had a drop height of 25 m in dry sand. In comparison, the vertical influence depth and radius reduced to less than 3 m and 2 m, respectively, when the anchor was released from 10 m height and fell into the seabed with a water depth of 15 m. It is also found that the dynamically penetrating anchors could significantly influence the earth pressure in clay. There is a non-linear increase in the measured penetration depth with kinematic energy, and the resulted maximum earth pressure increased dramatically with an increase in kinematic energy. Results from centrifuge model tests in this study provide useful insights into the penetration mechanism of a dropped anchor, which provides valuable data for design and planning of future submarine structures.

Micro gadolinium oxide dispersed flexible composites developed for the shielding of thermal neutron/gamma rays

  • Boyu Wang;Xiaolin Guo;Lin Yuan;Qinglong Fang;Xiaojuan Wang;Tianyi Qiu;Caifeng Lai;Qi Wang;Yang Liu
    • Nuclear Engineering and Technology
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    • 제55권5호
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    • pp.1763-1774
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    • 2023
  • In this study, a series of flexible neutron/gamma shielding composites are fabricated through the doping of Gd2O3 into the matrix of SEBS with (MGd2O3: MSEBS) % from 5% to 100%. Neutron transmittance test shows an exponential attenuation with the increase of areal density of Gd, in which the transmittance T ranges from 59.1440% to 35.3026%, with standard deviation less than 2.2743%, mass attenuation coefficient 𝜇m from 0.3194 cm2/g to 0.4999 cm2/g, and half value layer-HVL value from 2.4530 mm to 1.1313 mm. Shielding efficiency of the Gd2O3/SEBS composites is basically improved in comparison with that of B4C/SEBS. The transmittance T, mass/linear attenuation coefficient 𝜇m and 𝜇, HVL and effective atomic number Zeff for the shielding of γ rays (39 keV, 59 keV and 122 keV) are measured and calculated with XCOM as well as MCX programs. Finally, plots of the three dimensional relationships between transmittance, doping amount and thickness are provided to the guidance for engineering shielding design. In summary, the Gd2O3/SEBS composite is proved to be an effective flexible neutron/low energy γ rays shielding material, which could be of potential applications in the field of nuclear technology and nuclear engineering.

배수전단시험을 이용한 화강토의 다일레이턴시 특성 고찰 (Dilatancy Characteristics of Decomposed Granite Soils in Drained Shear Tests)

  • 강진태;김종렬;김승곤;박화정
    • 대한토목학회논문집
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    • 제28권2C호
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    • pp.117-123
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    • 2008
  • 풍화도가 다른 교란 및 불교란 화강토를 채취하고 일련의 실내시험(압밀배수시험, 평균주응력일정시험 등)을 실시하여 전단 중 발생되는 체적변화인 다일레이턴시(dilatancy) 특성을 분석하였다. 그 결과, 화강토의 다일레이턴시 영향으로 배수전단시험에서 평균주응력의 증가와 더불어 함수비는 감소하고, 풍화도가 낮은 경우의 불교란 화강토는 전단과정 중 어느 일정한계에서는 함수비의 증가를 보였다. 전단에 의한 체적변화량과 주응력차의 관계에서 ${\Delta}V_d/V_1=D{\cdot}(({\sigma}_1-{\sigma}_3)-{\sigma}_c)/{{\sigma}_m}^{\prime}$의 직선관계가 성립된다.

시험도로 아스팔트 포장의 공용성 변화 분석 (Performance Evaluation of Asphalt Concrete Pavements at Korea Expressway Corporation Test Road)

  • 서영국;권순민
    • 대한토목학회논문집
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    • 제28권1D호
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    • pp.35-43
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    • 2008
  • 본 연구는 지난 4년간 한국도로공사 시험도로 아스팔트 포장의 주요 손상인자의 정량화와 그 변화를 다루고 있다. 포장상태조사 장비인 ARAN(Automatic Road Analyzer)을 이용하여 준공 직후인 2002년 12월부터 2006년 10월까지 총 5차례에 걸쳐 아스팔트 전단면에 대해 노면상태를 측정하고 소성변형, 균열손상, 그리고 종단평탄성을 중심으로 그 결과를 분석하였다. 실내시험을 통해 시험도로의 아스팔트 혼합물의 온도와 하중 재하속도에 대한 선형점탄성 거동을 비교하고, 표층용 혼합물인 ASTM 19mm에 대해서는 동탄성계수에 미치는 공극률의 영향도 검토하였다. 일반 밀입도 표층 단면의 차륜부에서 추출한 시편의 공극률을 측정하여 시험도로 포장의 다짐도 변화를 추정하였으며 이를 바탕으로 다짐도-포장 손상의 관계를 검토하였다. 교통하중과 포장 손상과의 연관성 분석 결과 소성변형과 균열을 포함한 노면 손상의 증가는 교통하중이 재하되는 시기와 바로 일치하지는 않았으며 오히려 온도와 같은 환경에 더 영향을 받는 것으로 관측되었다. 반면에 노면 평탄성은 공용년수가 증가 하면서 교통하중에 민감하게 반응하였으며 환경인자와의 상관성은 매우 낮은 것으로 나타났다.