• Journal of Biomedical Engineering Research
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• v.15 no.2
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• pp.143-150
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• 1994

Wall shear rate or stress is believed to be a major hemodynamic variable influencing atherosclerosis and artery-graft anastomic intimal hyperplasia. The purpose of this study is to verify the effects of radial wall motion, artery-graft compliance and diameter mismatch, and impedance phase angle on the wall shear rate distribution near an end-to-end artery-graft anastomosis model. The results show that radial wall motion of the elastic artery model lowers the mean wall shear rates under pulsatile flow condition by 15 to 20 % comparing to those under steady flow condition at the same mean flow rate. Impedance phase angle seems to have small effects on the mean and amplitude of the wall shear rate distribution. In order to study the effects of compliance and diameter mismatch on the wall shear rates, two models are studied-Model I has 6% and Model I has 6% and Model II has 11% smaller graft diameter. Divergent geometry caused by diameter mismatch near the distal sites reduces the mean wall shear rates significantly, and this low shear region is believed to be prone to intimal hyperplasia.

• Journal of Drive and Control
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• v.13 no.1
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• pp.34-42
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• 2016

This study studied how the clearance, overlap and mismatch errors of spool-sleeve affect the static pressure characteristics of a servo valve. A computer simulation model was established as a direct acting servo valve and a series of simulations was conducted for various values of clearance, overlap and mismatch errors. Pressure gain decreased as the clearance increased. The overlap also affects the pressure gain and was similar to the effect of clearance. Asymmetry of the pressure plot got worse and worse as the mismatch error increased.

• Journal of the Korean Institute of Telematics and Electronics
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• v.23 no.5
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• pp.597-604
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• 1986

This paper describes various mismatch phenomena in differential pulse code modulation (DPCM) coding, such as the mismatch effects of probability density functin(pdf), signal variance, and correlation. At a high transmission rate(i.e., above 32 kbits/s), the performance of DPCM can be improved by matching the pdf shape between the input signal and the quantizer. However, the same gain cannot be obtained at a lower transmission rate. Also, it is shown that the gamma quantizer is realtively robust to the variation of pdf shaper and signal variance. Moreover, as the transmission rate increases, the performance of DPCM for the input signal with large variance is worse than that of DPCM for the signal with small variance due to the increase of overload noise. According to our simuladiton results, the mismatch effects of pdf shape and variance appear to yield more degradatin than that of correlation in a DPCM system.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.49 no.3
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• pp.74-80
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• 2012

In resolution-constrained quantization, the size of Voronoi cell varies depending on probability density function of the input data, which causes large amount of distortion outliers. We propose a vector quantization method that reduces distortion outliers by combining the generalized Lloyd algorithm (GLA) and the cell-size constrained vector quantization (CCVQ) scheme. The training data are divided into the inside and outside regions according to the size of Voronoi cell, and consequently CCVQ and GLA are applied to each region, respectively. As CCVQ is applied to the densely populated region of the source instead of GLA, the number of centroids for the outside region can be increased such that distortion outliers can be decreased. In real-world environment, source mismatch between training and test data is inevitable. For the source mismatch case, the proposed algorithm improves performance in terms of average distortion and distortion outliers.

• Current Photovoltaic Research
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• v.7 no.4
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• pp.111-120
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• 2019

The output power of a crystalline silicon (c-Si) photovoltaic (PV) module is not directly the sum of the powers of its unit cells. There are several losses and gain mechanisms that reduce the total output power when solar cells are encapsulated into solar modules. Theses factors are getting high attention as the high cell efficiency achievement become more complex and expensive. More research works are involved to minimize the "cell-to-module" (CTM) loss. Our paper is aimed to focus on electrical losses due to interconnection and mismatch loss at PV modules. Research study shows that among all reasons of PV module failure 40.7% fails at interconnection. The mismatch loss in modern PV modules is very low (nearly 0.1%) but still lacks in the approach that determines all the contributing factors in mismatch loss. This review paper is related to study of interconnection loss technologies and key factors contributing to mismatch loss during module fabrication. Also, the improved interconnection technologies, understanding the approaches to mitigate the mismatch loss factors are precisely described here. This research study will give the approach of mitigating the loss and enable improvement in reliability of PV modules.

• The Journal of the Korea Contents Association
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• v.8 no.7
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• pp.1-8
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• 2008

In this paper, an algorithm to compensate the inter-view mismatch in the multi-view video according to the different characteristics of cameras is presented. Interview mismatches make it difficult to merge the multi-view images and decrease the coding performance. So, a preprocessing operation to compensate the mismatches is requisite in the multi-view video coding. It is shown that the mismatch in the outputs of multi-view cameras with different electro-optical transfer functions can be approximated with a linear model of a gain and an offset. In addition, a new algorithm for estimating and compensating the inter-view mismatch based on the detection of the overlapped region is presented. Experimental results using various rectified stereo images show that the proposed method compensates inter-view mismatches more accurately compared to the conventional approach.

• Journal of the Korean Geographical Society
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• v.51 no.1
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• pp.41-56
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• 2016

This study investigates the employment and spatial mismatch as a significant acting factor of deepening urban poverty and analyses the placeness of regional labor market that the more efficient place-based labor market intervention needs to take into account. The change of unemployment rate as a regional labor market outcome in metropolitan cities is determined by the dynamic interaction between disequilibrium of labor supply and demand and employment mismatch according to various labor market conditions and its process is certainly differentiated across the metropolitan regional labor markets. In addition, it is analyzed that during the employment suburbanization the spatial mismatch puts differentiated impacts on different labor groups through human capital requirements and industry-selective job opportunities. As a result, because this whole process works with its unique process within individual regional labor markets, in order to link between urban poverty and employment mismatch and to promote problem-solving labor market intervention, we need to develop place-based policy based on the placeness of regional labor marekt.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.420-423
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• 2015

This paper proposes a method of non-linearity error detection and calibration for binary-weighted charge-driven DACs. In general, the non-linearity errors of DACs often occur due to the mismatch of layout designs or process variation, even when careful layout design methods and process calibration are adopted. Since such errors can substantially degrade the SNDR performance of DAC, it is crucial to accurately measure the errors and calibrate the design mismatches. The proposed method employs 2 identical DAC circuits. The 2 DACs are sweeped, respectively, by using 2 digital input counters with a fixed difference. A comparator identifies any non-linearity errors larger than an acceptable discrepancy. We also propose a calibration method that can fine-tune the DAC's capacitor sizes iteratively until the comparator finds no further errors. Simulations are presented, which show that the proposed method is effective to detect the non-linearity errors and calibrate the capacitor mismatches of a 12-bit DAC design of binary-weighted charge-driven structure.

• Safety and Health at Work
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• v.12 no.1
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• pp.96-101
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• 2021

Background: Many studies have reported noticeable increases in the proportion of employees working either relatively short or relatively long hours. Such trends have been accompanied by an increasing concern regarding work hour mismatches defined as a discrepancy between actual and preferred work hours. The aim of this study was to investigate association between work hour mismatch and depression. Methods: Data regarding work hour mismatches for 47,551 adults were extracted from the 2017 Korean Working Conditions Survey. The World Health Organization-Five Well-Being Index was used to measure depression. Multiple logistic regression analyses were performed to examine the association between work hour mismatch and depression. Results: Men and women workers with work hour mismatch were more likely to have depression [underemployed males: odds ratio (OR) = 1.30, 95% confidence interval (CI) = 1.14-1.49, overemployed males: OR = 1.28, 95% CI = 1.18-1.40; underemployed females: OR = 1.37, 95% CI = 1.20-1.56, overemployed females: OR = 1.12, 95% CI = 1.02-1.23]. Underemployed workers, workers who worked more than 52 hours per week, and workers with a high income level, all had higher ORs for depression. The greater the discrepancy between actual and preferred work hours, the higher OR for depression among both underemployed and overemployed workers. Conclusions: A difference between actual and preferred work hours was associated with depression. Underemployed workers had a higher risk of depression than that of overemployed workers. As a work hour mismatch negatively affected workers' mental health, it is important to reduce work hours mismatches as well as shorten the absolute number of work hours.

• Journal of the Korean Regional Science Association
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• v.39 no.4
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• pp.3-17
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• 2023

This study aims to comprehensively assess the phenomenon of structural unemployment, with a specific emphasis on unemployment resulting from spatial mismatch, while also exploring potential solutions. Spatial mismatch unemployment presents a unique challenge distinct from unemployment stemming from demand deficient, thus requiring a more multifaceted approach beyond the efforts of individual businesses and national economic recovery policy. To underscore the importance of addressing spatial mismatch, this research seeks to quantify its contribution to overall unemployment. Additionally, we evaluate the effectiveness of local labor markets, a prominent mechanism for alleviating spatial mismatch, categorized by occupation, to assess their effectiveness for addressing this issue. Through this analysis, our study advocates for the development of comprehensive policies within the realm of job-related initiatives, including spatial alignment through inter-regional collaborations, in conjunction with region-specific policies and strategies for job creation.