• The Korean Journal of Applied Statistics
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• v.29 no.5
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• pp.787-806
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• 2016

Mixed-mode (MM) designs in which data are collected by different modes in one design have become increasingly popular. An MM data collection has several advantages such as reductions of coverage error, non-response and cost. However, MM designs may introduce mode effects that are confounded by selection effects and measurement effects, which can make MM data quality poor. In order to investigate mode effects, SRI implemented a concurrent mixed-mode experiment in 2014 where respondents could choose between a self-administrated Web survey and a self-administrated paper survey. This paper separately estimates selection effects and measurement effects. We found that measurement effects on some items are large.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1999.04a
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• pp.23-23
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• 1999

후류손실을 가지는 혼합 전단층에 대하여 밀도변화가 없는 유동 및 밀도변화가 있는 유동의 선형 불안정성 해석을 수행하였다. 기본 유동의 속도장 및 밀도장은 tanh 함수를 사용하였으며, Gaussian 형태의 해석적 함수를 사용하여 두 유동을 분리시키는 평판 바로 다음에 존재하는 후류 손실 유동을 포함시켰다. 공간적 선형 불안정성 해석을 수행하여 불안정성 모드의 성장률과 파장속도를 주파수의 함수로서 구하였다. 해석 결과로부터 후류 손실을 가지는 혼합층은 sinuous 모드와 varicose 모드의 두 개의 불안정성 모드를 가짐을 알았다. 밀도가 균일한 경우에는 varicose 모드보다 sinuous 모드가 지배적이다. 밀도가 균일한 경우에는 varicose 모드보다 sinuous 모드가 지배적이다. 밀도구배가 존재하나 빠른 자유유동의 밀도가 높은 경우에는 밀도가 균일한 경우와 마찬가지로 sinuous 모드가 지배적인 모드가 된다. 그러나 느린 자유 유동의 밀도가 높은 경우에는 밀도장의 두께가 속도장의 두께보다 상대적으로 얇아지면 varicose 모드가 sinuous 모드보다 더욱 불안정하여질 수 있다. varicose 모드와 sinuous 모드의 성장률이 비슷한 밀도장의 두께에서는 두 불안정성 모드가 주파수 변화에 따라 분지 되어지는 경향을 보인다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.2
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• pp.279-286
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• 2015

EMD is a fully data-driven signal processing method without using any predetermined basis function and requiring any user parameters setting. However EMD experiences a problem of mode mixing which interferes with decomposing the signal into similar oscillations within a mode. To overcome the problem, EEMD method was introduced. The algorithm performs the EMD method over an ensemble of the signal added independent identically distributed white noise of the same standard deviation. Even so EEMD created problems when the decomposition is complete. The ensemble of different signal with added noise may produce different number of modes and the reconstructed signal includes residual noise. This paper propose an modified EEMD method to overcome mode mixing of EMD, to provide an exact reconstruction of the original signal, and to separate modes with lower cost than EEMD's. The experimental results show that the proposed method provides a better separation of the modes with less number of sifting iterations, costs 20.87% for a complete decomposition of the signal and demonstrates superior performance in the signal reconstruction, compared with EEMD.

• Composites Research
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• v.23 no.4
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• pp.21-27
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• 2010

In most engineering structures, fracture often takes place due to fatigue. Therefore, many studies about the effect of the various mode-mixities on fatigue characteristics have been performed. However, most of the former studies only address metal/metal interfaces or delamination of composite. In this study, the fatigue characteristics of composite/metal interfaces are investigated. The fatigue tests were performed using single leg bending(SLB)specimens that comprise composite and steel bonded to each other using co-cure bonding method. This paper focuses on fatigue characteristics depending on different mode ratios$(G_{II}/G_T$. The overall results obtained in this study show that the crack propagation rate increases with the mode II loading component.

• Composites Research
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• v.12 no.3
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• pp.66-74
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• 1999

A modified mixed mode bending test was performed to investigate the mixed mode delamination for carbon/epoxy composite material. Various mixed mode ratios could be produced by changing the applied load position on the loading lever and the bending load position on the specimen. The modified mixed mode bending test was analyzed to obtain strain energy release rates using beam theory, compliance method and finite element method, This results were in good agreement with the experimental result, which confirmed the validity of this test.

• Journal of the Korean Society of Propulsion Engineers
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• v.3 no.2
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• pp.10-17
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• 1999

This paper investigates the linear stability of both uniform and non-uniform density plane mixing layers with special emphasis on the effect of the wake component in the velocity profile. Velocity and density profiles for laminar flows are obtained from analytic profiles. Mixing layers with wakes have two generalized inflection points and two unstable modes-sinuous and varicose modes. For uniform density mixing layers, sinuous modes are more unstable than varicose modes, which shows wakes will be destabilized by sinuous modes. For non-uniform density mixing layers with high density in high speed flows, sinuous modes are more unstable than varicose modes. For non-uniform density mixing layers with high density in low speed flows, varicose modes can be more unstable than sinuous modes.

• Membrane Journal
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• v.23 no.5
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• pp.352-359
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• 2013

In the present study, $CO_2$ permeation through a hydrophilic NaY zeolite membrane was studied under permeate evacuation mode for $CO_2$ single gas, $CO_2-N_2$ and $CO_2-O_2$ binary mixtures, and $CO_2-N_2-O_2$ ternary mixture. It was reconfirmed that the $CO_2$ permeation was governed by surface diffusion and the $CO_2$ selectivity was induced from blocking effect of adsorbed $CO_2$ molecules. The $CO_2$ permeance measured in permeate evacuation mode was much lower than that done in He sweeping mode, but was comparable to that obtained under feed pressurization mode. The NaY zeolite membrane showed a considerable $CO_2$ separation for $14%CO_2-80%N_2-6%O_2$ mixture : $CO_2$ permeance was about $1{\times}10^{-7}mol/m^2secPa$ and $CO_2$ selectivity was more than 10. Therefore, it was concluded that NaY zeolite membrane was one of promising membranes for post-combustion CCS process.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.12
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• pp.3055-3062
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• 2014

3D integral imaging technique with an active mask is capable of displaying real 3D images with high resolution in space. In this paper, we present a novel 3D/2D convertible integral imaging display system using an active mask. For the proposed method, the principles of 3D, 2D, and 3D/2D composed operations are explained according to the displayed images through two LCD panels. In 3D mode, the elemental images and the mask images are displayed in two display panels. On the other hand, the light source image and 2D image are displayed in 2D mode. In addition, 3D/2D mode is obtained using the spatial separation for 3D and 2D modes. To show the feasibility of the proposed method, we carry out the preliminary experiments and present the optical results.

• 한국해양학회지
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• v.30 no.1
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• pp.1-12
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• 1995

The modal analysis was carried out for the total of 216 subface sediments of southern continental shelf of Korean peninsula. Sandy mud or muddy sand distributed in the range of 70∼100 m water depth revealed the bimodal type (sand and mud components). The relations of textural parameters obtained from every modal were consistent with those of shallow marine sediments. The characteristics of sand component between bimodal were as follows: (1) the distributions of mean grain size, sorting, shell content were repeatedly distributed like the directions of depth contour lines. (2) Sand component was composed of medium to fine sand (Mz, 1-3$\psi$) containing many shell fragments, a few pebbles, and iron-stained quartz. (3) The surface of quartz revealed the concordial breakage and V-shaped features formed at high energy environment. (4) In CM-pattern, sand component was plotted in rolling and bottom suspension area. These characteristics imply that sand component probably derives from shoreface sediments deposited at the beach environment.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.8
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• pp.1458-1467
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• 1992

Recently, the composite materials have been researched actively by many researchers because of its useful properties. Especially, an interface crack on the dissimilar material exposes the behavior of the mixed mode crack even though under only the tension stress. In the previous papers, crack energy density(CED) was shown as the crack behavior evaluation parameter which can be expressed consistently from the onset until a final fracture. In a present paper, the basic properties of CED on the interface crack are examined because the results by CED at the homogeneous material above are also expected to be held at the dissimilar material. And we proposed that the contribution of each mode of CED can be separated and be evaluated. Furthermore, the total CED and contribution of each mode are evaluated by domain integral through a finite element analysis at the elastic crack model and the basic examination are carried out.