• Steel and Composite Structures
• /
• 제22권3호
• /
• pp.691-712
• /
• 2016

In this editorial, buckling analytical investigation of the nanocomposite plate with square cut out reinforced by carbon nanotubes (CNTs) surrounded by Pasternak foundation is considered. The plate is presumed has square cut out in center and resting on Pasternak foundation. CNTs are used as amplifier in plate for diverse distribution, such as uniform distribution (UD) and three patterns of functionally graded (FG) distribution types of CNTs (FG-X, FG-A and FG-O). Moreover, the effective mechanical properties of nanocomposite plate are calculated from the rule of mixture. Domain decomposition method and orthogonal polynomials are applied in order to define the shape function of nanocomposite plate with square cut out. Finally, Rayleigh-Ritz energy method is used to obtain critical buckling load of system. A detailed parametric study is conducted to explicit the effects of the dimensions of plate, length of square cut out, different distribution of CNTs, elastic medium and volume fraction of CNTs. It is found from results that increase the dimensions of plate and length of square cut out have negative impact on buckling behavior of system but considering CNTs in plate has positive influence.

• Steel and Composite Structures
• /
• 제34권2호
• /
• pp.289-297
• /
• 2020

In the present research post-buckling of a cut out plate reinforced through carbon nanotubes (CNTs) resting on an elastic foundation is studied. Material characteristics of CNTs are hypothesized to be altered within thickness orientation which are calculated according to Mori-Tanaka model. For modeling the system mathematically, first order shear deformation theory (FSDT) is applied and using energy procedure, the governing equations can be derived. With respect to Rayleigh-Ritz procedure as well as Newton-Raphson iterative scheme, the motion equations are solved and therefore, post-buckling behavior of structure will be tracked. Diverse parameters as well as their reactions on post-buckling paths focusing cut out measurement, CNT's volume fraction and agglomeration, dimension of plate and an elastic foundation are investigated. It is revealed that presence of a square cut out can affect negatively post-buckling behavior of structure. Moreover, adding nanocompsits in the matrix leads to enhancement of post-buckling response of system.

• Advances in nano research
• /
• 제7권6호
• /
• pp.405-417
• /
• 2019

This research is devoted to study post-buckling analysis of functionally graded carbon nanotubes reinforced composite (FG-CNTRC) micro plate with cut out subjected to magnetic field and resting on elastic medium. The basic formulation of plate is based on first order shear deformation theory (FSDT) and the material properties of FG-CNTRCs are presumed to be changed through the thickness direction, and are assumed based on rule of mixture; moreover, nonlocal Eringen's theory is applied to consider the size-dependent effect. It is considered that the system is embedded in elastic medium and subjected to longitudinal magnetic field. Energy approach, domain decomposition and Rayleigh-Ritz methods in conjunction with Newton-Raphson iterative technique are employed to trace the post-buckling paths of FG-CNTRC micro cut out plate. The influence of some important parameters such as small scale effect, cut out dimension, different types of FG distributions of CNTs, volume fraction of CNTs, aspect ratio of plate, magnitude of magnetic field, elastic medium and biaxial load on the post-buckling behavior of system are calculated. With respect to results, it is concluded that the aspect ratio and length of square cut out have negative effect on post-buckling response of micro composite plate. Furthermore, existence of CNTs in system causes improvement in the post-buckling behavior of plate and different distributions of CNTs in plate have diverse response. Meanwhile, nonlocal parameter and biaxial compression load on the plate has negative effect on post-buckling response. In addition, imposing magnetic field increases the post-buckling load of the microstructure.

• 한국공작기계학회논문집
• /
• 제13권2호
• /
• pp.9-16
• /
• 2004

Because a generated heat during grinding operation makes a serious deformation on a ground surface as a convex form, a real depth of cut in deformed zone has larger than an ideal depth of cut. Consequently, the ground surface has a geometric error as a concave form after cooling the workpiece. In this study, the force and the geometric error of surface grinding were examined. From evaluating magnitude and mode of the geometric error according to grinding conditions, an optimal grinding condition was proposed to minimize the geometric error. In addiction the relationship between the geometric error and the grinding force was found out. Due to least square regression it was able to predict the geometric error by using the grinding force.

• Nutrition Research and Practice
• /
• 제1권3호
• /
• pp.218-223
• /
• 2007

This study investigated: 1) what weight-related behaviors college students practiced; 2) if the behaviors were performed for weight-related reasons; and 3) whether the behavioral practices differed by gender, race, and body weight status. This cross-sectional study used a questionnaire to collect information from a non-probability sample of undergraduate students (n=379; 48% men) recruited from large introductory psychology classes. Chi-square tests were conducted to examine simple comparisons, and multiple logistic regression analyses assessed differences. Male students reported adopting significantly fewer weight-related behaviors than females. Most frequently males increased exercise (69.2%), increased fruit and vegetable consumption (50%), skipped meals (46%), cut out sweets and junk foods (40%), and cut out between-meal snacks (35%). Female students most frequently increased exercise (67.4%), skipped meals (63%), increased fruit and vegetable consumption (62%), reduced the amount of food eaten (60%), and cut out between-meal snacks (51%). Negative behaviors were engaged in by only a few participants. Weight-related reasons were a significant factor for weight-related behavior adoption. Multiple logistic regression analyses showed that gender was consistently and significantly associated with the adoption of weight-related behaviors, while race and weight status were less consistently associated. Findings of this study will be helpful to dietitians who counsel college students. Results of this study may support effects to bring more comprehensive behaviorally-focused health md nutrition interventions to college campuses.

• Wind and Structures
• /
• 제1권4호
• /
• pp.351-364
• /
• 1998

In wind tunnel experiments, the blockage effect is a very important factor which affects the test results significantly. A number of investigations into this problem, especially on the blockage correction of drag coefficient, have been carried out in the past. However, only a limited number of works have been reported on the wind tunnel blockage effect on wind-induced vibration although it is considered to be fairly important. This paper discusses the aerodynamic characteristics of the square model and square model with corner cut based on a series of the wind tunnel tests with various blockage ratios and angles of attack. From the test results, the aerodynamic behavior of square models with up to 10% blockage ratio are almost the same and square models with up to 10% blockage ratio can be tested as a group which behaves similarly.

• 한국정보통신학회논문지
• /
• 제8권7호
• /
• pp.1399-1404
• /
• 2004

컴퓨터의 발전과 정보통신기술의 발달은 멀티미디어 기술 확산과 대용량의 멀티미디어 동영상데이터 사용을 증가시켰다. 동영상데이터는 전체적인 데이터를 파악하고, 원하는 동영상을 바로 재생 가능할 뿐만 아니라 동영상 데이터의 정보가 된 리스트제공이 필요하다. 그리고 효과적인 동영상 검색을 위해서는 동영상 데이터의 색인과정이 필수적이며 꼭 필요한 기술이다. 따라서 본 연구는 동영상 데이터 내용기반 색인에 기초가 될 프레임의 컷 검출의 효과적인 방법을 제안한다. 제안된 방법은 동영상데이터 각각의 프레임을 대각선 방향으로 나누어 일정한 픽셀 색상 정보 값을 추출하여 각각 프레임에서 추출된 칼라색상의 픽셀값은 A(i, ij행렬로 j는 프레임 수, i는 프레임의 영상 높이로 저장한다. 저장되어진 픽셀값은 MSE(Mean Square Error)을 이용하여 프레임간의 특정 값의 차이를 임계 값보다 클 경우 빠르고 정확하게 컷을 검출하였다. 프레임 컷 검출에 대한 실험을 포괄적으로 하기 위해 여러 종류의 동영상 데이터를 실험 대상으로 하여 컷 검출 시스템의 성능을 비교 분석하였다.

• 인터넷정보학회논문지
• /
• 제3권5호
• /
• pp.51-62
• /
• 2002

컴퓨터의 발전과 정보통신기술의 발달은 멀티미디어 기술 확산과 대용량의 멀티미디어 동영상데이터 사용을 증가시켰다. 동영상데이터는 전체적인 데이터를 파악하고, 원하는 동영상을 바로 재생 가능할 뿐만 아니라 동영상 데이터의 정보가 요약된 리스트제공이 필요하다. 그리고 효과적인 동영상 검색을 위해서는 동영상 데이터의 색인과정이 필수적이며 꼭 필요한 기술이다. 따라서 본 연구는 동영상 데이터 내용기반 색인에 기초가 된 프레임의 짓 검출의 효과적인 방법을 제안한다. 제안된 방법은 프레임의 대각선 방향으로 나누어 일정한 픽셀 색상 정보 값을 추출하였다 동영상 데이터의 각각 프레임에서 추출된 칼라색상의 픽셀값은 A(j, i)행렬로 i는 프레임 수. j는 프레임의 영상 높이로 저장한다. 저장되어진 픽셀값은 프레임간의 색상차의 자승합을 이용하여 프레임간의 특정 값의 차이를 임계 값보다 클 경우 빠르고 정화하게 컷을 검출하였다. 프레임 컷 검출에 대한 실험을 포괄적으로 하기 위해 여러 종류의 동영상 데이터를 실험 대상으로 하여 컷 검출 시스템의 성능을 비교 분석하였다.

• Asian-Australasian Journal of Animal Sciences
• /
• 제4권1호
• /
• pp.7-14
• /
• 1991

An experiment was carried out to investigate the effect of change in length of hay offered on eating and rumination behaviour in sheep using three types of hay diets (L: long, M: 8.0-cm cut, S: 1.2-cm cut) and 3 Japanese Corriedale wethers, and the experiment was designed as $3{\times}3$ latine square. The time spent eating per 100 g hay was significantly shorter with long (L) hay (p < 0.05) than with chopped (M and S) hay, and therefore, the eating rate (g D.M./min.) was significantly higher in the former (p < 0.05) than in the latter. Rumination appearance (the lag time after eating) tended to be longer with long hay than with chopped hay, but not significantly (p > 0.05). Daily time spent ruminating, the actual chewing time and daily number of chews tended to be more in feeding long hay than in feeding chopped hay, but not significantly. Daily number of rumination periods was significantly more with long hay (p < 0.01) than with chopped hay. Cyclic rate tended to be longer with long hay than with chopped hay, in particular, the difference in values between long hay and 8.0-cm cut hay was significant statistically (p < 0.01). The rumination index (time spent ruminating/100 g D.M, eaten) tended to be higher with long hay than with chopped hay, and the difference in values between long hay and 1.2-cm cut hay was significant statistically (p < 0.05). Bolus time was significantly longer with long hay (p < 0.01) than that with 8.0-cm cut hay. The circadian pattern of ruminating time was not changed by the changes in length of hay eaten.

• 수산해양기술연구
• /
• 제30권2호
• /
• pp.125-131
• /
• 1994

This paper describes a method to measure the distortion level of loudspeaker using a LMS(Least Mean Square) adaptive filter. Conventional technique to measure the distortion level uses a band-pass filter with a sharp cut-off frequency characteristics. However. such the band-pass filter has a bed time response characteristics. On the other hand, the proposed method offers us an easy way to measure the specified harmonic distortion level with a small hardware. Moreover, our method is not affected by noise which has no correlation with the test signal, and the measurement can be carried out in a noisy environment. The effectiveness of the proposed method is confirmed by experiment using a loudspeaker in a noisy room.