• International Journal of Costume and Fashion
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• 제13권2호
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• pp.65-77
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• 2013

The purposes of this study were to document the fashions adopted by young women in the United States in the 1980s and to explore if and how the dynamic shifts toward postmodernist values influenced those fashion trends. Fifteen U.S. women who were college students in the 1980s were interviewed for the study. In analysis of the data, we focused on social changes during the 1980s and the cultural impact of postmodernism vs. modernism as influential factors. Both postmodern and feminist ideas challenged the mainstream cultural framework of capitalism. U.S. women's styles and behaviors concerning dress reflected characteristics of postmodern consumption patterns, which include nostalgia, ethnic dress, androgyny, eclectic and novel clothing combinations, surprising or humorous appearance, and nonconformity. Despite the critique of conformity and conservatism in dress that had emerged in the 1960s and remained in at least minority or subversive trends, the importance of brand names and designer labels increased in mainstream fashion. This study helps us better understand the dynamics of fashion as it reflects societal and value changes in a transitional time in history.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.616-621
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• 2003

Fluid-elastic instability is believed to be a cause of the large-amplitude vibration and resulting rapid wear of heat exchanger tubes when the flow velocity exceeds a critical value. For sub-critical flow velocities, the random turbulence excitation is the main mechanism to be considered in predicting the long-term wear of steam generator tubes. Since flow-induced interactions of the tubes with tube supports in the sub-critical flow velocity can cause a localized tube wear, tube movement in the clearance between the tube and tube support as well as the normal contact force on the tubes by fluid should be maintained as low as possible. A simplified method is used for predicting fretting-wear damage of the double $90^{\circ}$U-bend tubes. The approach employed is based on the straight single-span tube analytical model proposed by Connors, the linear structural dynamic theory of Appendix N-1300 to ASME Section III and the Archard's equation for adhesive wear. Results from the presented method show a similar trend compared with the field data. This method can be utilized to predict the fretting-wear of the double $90^{\circ}$U-bend tubes in steam generators.

• 전자공학회논문지SC
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• 제37권2호
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• pp.16-28
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• 2000

In this paper, we propose a navigation algorithm for a mobile robot, which is intelligently searching the goal location in unknown dynamic environments using an ultrasonic sensor. Instead of using "sensor fusion"method which generates the trajectory of a robot based upon the environment model and sensory data, "command fusion"method is used to govern the robot motions. The major factors for robot navigation are represented as a cost function. Using the data of the robot states and the environment, the weight value of each factor is determined for an optimal trajectory in dynamic environments. For the evaluation of the proposed algorithm, we peformed simulations in PC as well as real experiments with ZIRO. The results show that the proposed algorithm is apt to identify obstacles in unknown environments to guide the robot to the goal location safely.

• 한국통신학회논문지
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• 제29권9C호
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• pp.1258-1268
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• 2004

비디오화상회의 시스템을 위하여 동영상 압축 DCT 계수와 피부색정보를 이용하여 주파수 영역에서 정연 얼굴 을 실시간으로 검출하는 알고리즘을 제안한다. 동영상 압축과정 중에 얻어지는 DCT계수 값의 U 와 V 색상정보로 피부색 범위를 추출하며 잡음성분제거를 위해 형태학적필터와 Labeling을 적용하고 피부색블록의 방향성과 평탄도를 고려하여 검출하였다. 제안 알고리즘은, 배경에 피부색과 유사한 객체가 있는 경우와 배경이 단순한 경우에 대 해 적응적으로 검출이 가능하도록 하였다 여러 인종에 대한 모의실험결과 제안 알고리즘이 약 94% 의 검출 성공률을 보였다.

• Advances in nano research
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• 제16권4호
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• pp.413-426
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• 2024

This paper investigates the dynamic behavior of a simply supported viscoelastic plate made of functionally graded carbon nanotube reinforced composite under dynamic loading. Carbon nanotubes are distributed in 5 different shapes: U, V, A, O and X, depending on the shape they form through the thickness of the plate. The displacement fields are derived in the Laplace domain using a higher-order shear deformation theory. Equations of motion are obtained through the application of the energy method and Hamilton's principle. The resulting equations of motion are solved using Navier's method. Transforming the Laplace domain displacements into the time domain involves Durbin's modified inverse Laplace transform. To validate the accuracy of the developed algorithm, a free vibration analysis is conducted for simply supported plate made of functionally graded carbon nanotube reinforced composite and compared against existing literature. Subsequently, a parametric forced vibration analysis considers the influence of various parameters: volume fractions of carbon nanotubes, their distributions, and ratios of instantaneous value to retardation time in the relaxation function, using a linear standard viscoelastic model. In the forced vibration analysis, the dynamic distributed load applied to functionally graded carbon nanotube reinforced composite viscoelastic plate is obtained in terms of double trigonometric series. The study culminates in an examination of maximum displacement, exploring the effects of different carbon nanotube distributions, volume fractions, and ratios of instantaneous value to retardation times in the relaxation function on the amplitudes of maximum displacements.

• 한국자동차공학회논문집
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• 제14권6호
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• pp.17-23
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• 2006

Rubber materials have the nonlinear, large deformation and viscoelastic behavior. W.D. Kim et al. studied these characteristics through the static, fatigue, dynamic, aging and viscoelastic test. This paper discussed that the properties of engine mounting rubber, such as static stiffness, fatigue life and damping factor, are predicted based on CAE by using material properties acquired by the report of Kim et al. In result, the static stiffness of engine mounting rubber is predicted approximately in comparison with test value. Also, it was confirmed that the relationship of fatigue life and Green-Lagrange strain in specimen was the valid tool to predict the fatigue life of engine mounting rubber. From the results of transient viscoelastic analysis the damping factor changed rapidly at the range less than 8hz.

• 대한치과보철학회지
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• 제52권2호
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• pp.82-89
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• 2014

연구 목적: 본 연구의 목적은 중합 과정 중 치과용 레진 시멘트의 점탄성 성질의 변화를 관찰하기 위한 것이다. 연구 재료 및 방법: 6 종류의 레진시멘트(Clearfil SA luting, Panavia F 2.0, Zirconite, Variolink N, RelyX Unicem clicker, RelyX U200)가 이번 실험에 사용되었다. AR1500 stress controlled rheometer를 이용해 $32^{\circ}C$에서 동적 시간 경과 시험(dynamic oscillation time sweep test)이 시행되었다. 각각의 레진시멘트의 전단 저장 계수(G'), 전단 손실 계수(G"), 손실 탄젠트(tan ${\delta}$), 변위량을 20분 동안 3번씩 반복 측정하였다. 측정 결과는 일원배치분석 및 Tukey's hoc test로 사후 검정을 시행하였다(${\alpha}$=0.05). 결과: 모든 레진 시멘트는 혼합 후 시간에 따라 G' 값이 증가하였고, 최종적으로 안정상태에 도달하였다. 실험 종료 시점에서 RelyX U200은 가장 높은 G'값을 나타냈고, RelyX Unicem (clicker type)과 Variolink N이 가장 낮은 G'값을 나타냈다. Tan ${\delta}$와 변위량은 일정 수준의 값을 유지하다가 G'이 증가하기 시작하는 시점에서 0에 도달하였다. 이는 변위량이 0에 도달하는 지점과 거의 일치하였으며, 그 시간은 6분 내외였다. 결론: 본 연구에서 RelyX U200은 다른 레진 시멘트와 비교하여 가장 오랜 시간 동안 소성을 유지하고, 경화 완료 후 가장 높은 강도(rigidity)를 보였다. 따라서 여러 개의 보철물을 동시에 합착해야 하는 경우에 RelyX U200이 유용할 것으로 사료된다.

• The International Journal of Costume Culture
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• 제6권2호
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• pp.105-116
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• 2003

The purposes of this study were to examine the fashion adopted by young women in the United States in the 1970s and to explore how the dynamic shifts toward feminist values influenced those fashion trends. Fifteen American women who were college students in the 1970s were interviewed for the study. Throughout the decade, casual and comfortable styles became more prevalent; for example, pants became widely accepted for formal occasions as well as informal occasions due to an overall emphasis on practicality. The feminist and civil rights movements along with more liberal attitudes toward religion were among the more dominant cultural values that influenced the respondents' choices in clothing styles. Feminist presentation was diverse extreme or eclectic - and constantly renegotiating itself. This study helped us better understand the dynamics involved between fashion and value changes as well as the influence of feminism on the 1970s fashion in the United States.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2001년도 추계학술대회 논문집
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• pp.534-539
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• 2001

This paper presents the critical speed analysis of geogrid-reinforced rail roadbeds on soft soil. A rail roadbed on soft ground must be designed to avoid intolerable stress in the underlying soil and to give sufficient support for the rail system. At high speeds, the deformation of rail systems will gain dynamic amplification, and reach excessive values as a certain speed, here termed critical speed is approached. The elastic Winkler foundation model was used to predict the critical speed of geogrid-reinforced rail roadbeds on soft soil and the model properties were determined by the in-situ cyclic plate load test. Based on the parametric study of elastic beam on Winkler foundation model, the critical speed increase with the increase of the flexural risidity of subgrade EI and the stiffness coefficient of Winkler foundation k. From the in-situ cyclic load tests and analysis of elastic beam on Winkler foundation model, the critical speed increase with increase in number of reinforced layer and non-dimensional value for depth of first geogrid layers and the thickness of reinforced rail roadbed u/d.

• 한국가시화정보학회지
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• 제20권2호
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• pp.78-85
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• 2022

In these days, the rapid development in prediction technology using artificial intelligent is being applied in a variety of engineering fields. Especially, dimensionality reduction technologies such as autoencoder and convolutional neural network have enabled the classification and regression of high-dimensional data. In particular, pixel level prediction technology enables semantic segmentation (fine-grained classification), or physical value prediction for each pixel such as depth or surface normal estimation. In this study, the pressure distribution of the ship's surface was estimated at the pixel level based on the artificial neural network. First, a potential flow analysis was performed on the hull form data generated by transforming the baseline hull form data to construct 429 datasets for learning. Thereafter, a neural network with a U-shape structure was configured to learn the pressure value at the node position of the pretreated hull form. As a result, for the hull form included in training set, it was confirmed that the neural network can make a good prediction for pressure distribution. But in case of container ship, which is not included and have different characteristics, the network couldn't give a reasonable result.