• Communications for Statistical Applications and Methods
• /
• 제7권3호
• /
• pp.741-757
• /
• 2000

In may experimental situations, whenever a block design is used, the block effect is usually considered to be fixed. There are, however, experimental situations in which it should be treated as random. The choice of a blocking arrangement for a response surface design can have a considerable effect on estimating the mean response and on the size of he prediction variance even if the experimental runs re the same. Therefore, care should be exercised in the selection of blocks. In this paper, in the presence of a random block effect, we propose a graphical method or evaluating the effect of blocking in response surface designs using cuboidal regions. This graphical method can be used to investigate how the blocking has influence on the prediction variance throughout all experimental regions of interest when this region is cuboidal, and compare the block effects in the cases of the orthogonal and non-orthogonal block designs, respectively.

• Journal of the Korean Data and Information Science Society
• /
• 제21권2호
• /
• pp.231-240
• /
• 2010

4 $\times$ 4 균형불완전블럭모형에서 고정효과만이 존재하는 경우 주효과를 검정하기 위한 순위변환 통계량의 검정력은 적은 반복수에도 가장 높은 수준을 유지하며, 지수분포와 이중지수분포하에서는 모수적 통계량의 검정력보다 큰 격차의 상대적 우위를 보인다. 특히 전형적인 균형불완전블럭모형하에서 주인자는 고정이며 블럭인자는 랜덤인 경우의 순위변환 통계량의 검정력은 주효과의 효과크기 및 블럭효과의 모집단 분포와 모수크기에 상관없이 모든 상황에 걸쳐 현저하게 높은 우위성를 보인다. 또한 반복수가 증가함에따라 순위변환 통계량의 검정력은 빠른 속도로 증가한다. 전체적인 주효과의 순위변환 통계량의 검정력 우위는 하나의 주효과 및 블럭효과와 결측값이 존재하는 균형불완전블럭모형의 고유특성으로 말미암아 고정효과 및 표본의 작은 크기변화에 민감하게 반응하며 상대적 검정력 우위를 갖는다고 볼 수 있다.

• The Journal of Asian Finance, Economics and Business
• /
• 제8권12호
• /
• pp.261-269
• /
• 2021

This study examines the effect of block diversity on the risk of firms listed on the Korean Stock Exchange between 2010 and 2017. To examine the effect of block diversity on corporate risk, we measure block diversity in terms of a single component, portfolio size, by referring to prior literature. This diversity component accounts for the differences in portfolio size across corporate blocks. In line with existing research on corporate risk, we consider several variables to measure corporate risk: volatility, beta, and idiosyncratic risk. The results show a negative relationship between the size of a block shareholder's portfolio and corporate risk. We also show no difference in the effect of block diversity on the corporate risk between KOSPI and KOSDAQ. This implies that the difference in portfolio size among corporate blocks reduces corporate risk. This may be due to the effect of inter-block monitoring activities in the Korean securities market, which benefits from block diversity. This empirical result supports previous studies that predicted that block diversity would have beneficial influences on firm monitoring in general. This study is significant in that it analyzes the relationship between block diversity and firm risk and provides relevant information to business practitioners and investors.

• 한국컴퓨터정보학회논문지
• /
• 제7권4호
• /
• pp.102-107
• /
• 2002

블록 코딩을 기반으로 하는 영상의 압축 부호화는 영상 및 비디오 압축 표준으로 적용되어 왔다. 그런데 영상 복원 시 발생하는 블록효과에 대한 효율적인 측정방법을 찾아보기 힘든 실정이다. 본 논문에서는 서브블록 DCT부호화를 이용한 복원 영상에 대한 객관적인 블록효과 측정방법을 제안한다. 제안한 방법이 주관적인 순위매김과 일치하는 블록효과 측정방법임을 실험결과로서 입증한다 또한 제안한 이 새로운 측정방법은 복원 영상에서 쉽게 그리고 효율적으로 블록효과를 측정하는데 널리 사용될 수 있을 것으로 기대한다.

• 전자공학회논문지S
• /
• 제35S권5호
• /
• pp.68-74
• /
• 1998

Block-based interframe interpolation algorithms cause severe block effect because the algorithm interpolates the skipped frame by using block based motion vector. Therefore, in this paper, we propose an algorithm that reduces the block effect in the interpolated frames. First, we propose an algorithm that obtains backward motion vector by using forward motion vector received from the transmitter. In order to predict well covered and uncovered region, backward motion vector is needed as well as forward motion vector. Second, we propose the algorithm which segments the motion boundary blocks into regions and obtains the motion vector of each region from candidates that consist of the motion vectors of neighbor blocks. This algorithm makes it possible that the moving object and the background, in spite of being in the same block, have different motion vectors from each other so that the block effect can be reduced. According to the results of simulation, the proposed algorithm is superior to conventional algorithm in subjective quality a swell as in objective quality.

• The Korean Journal of Pain
• /
• 제1권2호
• /
• pp.188-191
• /
• 1988

Recent studies have shown that narcotic drugs produce an intense prolonged analgesic action when injected into the subarachnoidal or extradural space of animals and man. In order to study the effects of intrathecal injection of morphine on postoperative pain relief and segmental block effect, we administered 0.25 mg of morphine sulfate (0.25 mg of morphine/1 ml normal saline) into lumbar subarachnoid space prior to brahial plexus block for upper extremity surgery group The results were as follows: 1) more than 20 hours analgesic effect at least 2) no segemental block effect in analgesia 3) some adverse effect (Nausea, Vomiting, Pruritus, Urinary retention).

• 대한전자공학회논문지
• /
• 제25권6호
• /
• pp.663-671
• /
• 1988

In this paper, in order to reduce the blocking effect of block coded images, we propose the method considering the lowpass and bandpass components of Granrath's human visual model. This method consists of two-stage enhancement procedure. The first step is lowpass filtering which smooths out the blocking effect, and the second step is a high frequency enhancement procedure to increase the contrast decreased by the lowpass filtering in the first step. In the first step, the one-dimensional Gaussian filter which aligthns parallel to the edge direction is considered to preserve the edge in the block and the two-dimensional Gaussian filter is used to smooth out the blocking effect near the block boundaries. In the second step, the lowpass and bandpass components of the Granrath's model are considered to increase contrast in a restored image. The performance comparison of the proposed method and the existing mehtods is made by a computer simulation with several block coded images. We can see that the enhancement in the subjective quality of images of the proposed method is more significant than the enhancement in the subjective quality of images of the proposed method is more significant than the existing methods, though the proposed method does not show better performance on the PSNR gain, the poor measure of picture quality for block coded images.

• 한국대기환경학회지
• /
• 제16권6호
• /
• pp.641-652
• /
• 2000

The effect of block arrangement has been investigated on the particle deposition in the specified collecting cell of two-stage electrostatic precipitator by numerical analysis. Recirculation zone existed at the downstream of the block in the collecting cell, and the particles entering the recirculation zone were deposited on the collecting plate. Particle trajectory and deposition had considerably different phenomenon according to electrostatic and inertial effect, which depended on inlet mean velocity, electrostatic number, and particle diameter in the collecting cell. The total collection efficiency reached a minimum value through an interaction of electrostatic and inertial effect. In the computational domain, total collection efficiency for the case of two blocks in the computational domain was more than that of one block at the relative small electrostatic number. However as the block distance and inertial effect increased, the difference between the collection efficiency of two cases decreased. In the range of relatively small particle size total collection efficiency was always superior to particle collection efficiency that was predicted by Deutsch equation.

• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2003년도 The Fifth Asian Computational Fluid Dynamics Conference
• /
• pp.121-122
• /
• 2003

In this study a microchannel with various arrangement of blocks is newly proposed. This design comprises periodically arranged simple blocks. In this configuration, the stirring is greatly enhanced at a certain geometric parameter set. To characterize the flow field and the stirring effect both the numerical and experimental methods were employed. To obtain the velocity field, three-dimensional numerical computation to the Navier Stokes equations are performed by using a commercial code, FLUENT 6.0. The fluid-flow solutions are then cast into studying the characteristics of stirring with the aid of Lyapunov exponent. The numerical results show that the particles' trajectories in the microchannel heavily depend on the block arrangement. It was shown that the stirring is significantly enhanced at larger block-height and it reaches maximum when the height is 0.8 times the channel width. We also studied the effect of the block stagger angle, and it turns out that the stirring performance is the best at the block angel ${45^\circ}$.

• Journal of Welding and Joining
• /
• 제33권4호
• /
• pp.44-49
• /
• 2015

The structural epoxy adhesive used in car body assembly needs the highest level of joint mechanical strength under lap shear, T-peel and impact peel conditions. In this study, the effect of nano functionalized block copolymer addition on the impact peel strength of epoxy adhesive was investigated. DSC analysis showed that the addition of nano functionalized block copolymer did not affect the curing reaction of epoxy adhesive. From single lap shear test, it was found out that the addition of nano functionalized block copolymer slightly decreased the cohesive strength of cured adhesive layer. The addition of nano functionalized block copolymer showed beneficial effect on T-peel strength by changing the adhesive failure mode to the mixed mode. However, the addition of nano functionalized block copolymer just decreased the room temperature impact peel strength. It was considered that the addition of nano functionalized block copolymer could have effect on disturbing the crack propagation only for the case of slow strain rate.