• 대한의용생체공학회:의공학회지
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• 제13권4호
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• pp.339-352
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• 1992

A numerical simulation of the steady and pulsatile flow across the end-to-side anastomosis was performed In order to understand the role of flow dynamics in the preferential bevel opment of distal anastomotic intimal hyperplasla. The finite element technique was employed to solve two-dimensional unsteady pulsatile flow in that region. The results of the steady flow revealed that low shear stresses occur at the proximally occluded host artery and at the recirculation region in the Inner wall just distal to the toe region of the anastomosis. The nor- mal;zed wall shear rate was increased, as was the recirculation zone size in the host artery of the by-pass graft anastomosis, with increased anastomotic junction angle. In order to min imize the size of the low wall shear region which might result in the intimal hyperplasia in the by-pass graft anastomosis, a smaller anastomotic junction angle is recommended. The pulsatile flow simulation revealed flow that regions of low and ascillating mali shear do exist near the anastomosis as In the steady simulation. The shift of stagnation point depends on the pulsation of the flow. As the flow was accelerated at systole, the stagnation point moved downstream, disappered at early diastole and reappeared during late diastole. Low shear stress was also found along both walls of the occluded proximal artery. However, the diastolic flow behavior is quite different from the steady results. The vortex near the occluded artery moved downstream and inwardly during late systole, and disappeared during diastole. Recirculations proximal to the toe and heel regions were significant during diastole. Shear stress oscillation was found along the opposite wall. The results of the present study revealed that tow shear occurs at the proximally occluded host artery aud the recirculation region in the inner wall Just dlstal to the toe region of the anastomosis. The present study suggested that the regions of fluctuated wall shear stress wit flow separation is correlated with the preferential developing regions of anastomosis neointial fibrous hyperplasia.

• Industrial Engineering and Management Systems
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• 제13권4호
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• pp.357-368
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• 2014

Since its birth in 1993, fuzzy time series have seen different classes of models designed and applied, such as fuzzy logic relation and rule-based models. These models have both advantages and disadvantages. The major drawbacks with these two classes of models are the difficulties encountered in identification and analysis of the model. Therefore, there is a strong need to explore new alternatives and this is the objective of this paper. By transforming a fuzzy number to a real number via integrating the inverse of the membership function, new autoregressive models can be developed to fit the observation values of a fuzzy time series. With the new models, the issues of model identification and parameter estimation can be addressed; and trends, seasonalities and multivariate fuzzy time series could also be modeled with ease. In addition, asymptotic behaviors of fuzzy time series can be inspected by means of characteristic equations.

• Architectural research
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• 제14권1호
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• pp.11-18
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• 2012

College of Architecture, Georgia Institute of Technology, Atlanta, GA, US Abstract The intermittent heating and cooling energy need calculation of the ISO 13790 monthly method was examined. The current ISO 13790 method applies a reduction factor to the continuous heating and cooling need calculation result to derive the intermittent heating and cooling for each month. This paper proposes a method for the intermittent energy need calculation based on the internal mean temperature calculation. The internal temperature calculation procedure was introduced considering the heat-balance taking into account of heat gain, heat loss, and thermal inertia for reduced heating and cooling period. Then, the calculated internal mean temperature was used for the intermittent heating and cooling energy need calculation. The calculation results from the proposed method were compared to the current ISO 13790 method and validated with a dynamic simulation using EnergyPlus. The study indicates that the intermittent heating and cooling energy need calculation method using the proposed model improves transparency of the current ISO 13790 method and draws more rational outcomes in the monthly heating and cooling energy need calculation.

• Industrial Engineering and Management Systems
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• 제14권2호
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• pp.196-209
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• 2015

Retail sales forecast is a special area of forecasting. Its unique characteristics call for unique data models and treatment, and unique forecasting processes. In this paper, we will address lessons learned and challenges encountered in retail sales forecast from a practical and technical perspective. In particular, starting with the data models of retail sales data, we proceed to address issues existing in estimating and processing each component in the data model. We will discuss how to estimate the multi-seasonal cycles in retail sales data, and the limitations of the existing methodologies. In addition, we will talk about the distinction between business events and forecast events, the methodologies used in event detection and event effect estimation, and the difficulties in compound event detection and effect estimation. For each of the issues and challenges, we will present our solution strategy. Some of the solution strategies can be generalized and could be helpful in solving similar forecast problems in different areas.

• Journal of information and communication convergence engineering
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• 제14권1호
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• pp.40-44
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• 2016

The device coupling between the stacked top/bottom field-effect transistors (FETs) in two types of monolithic 3D inverter (M3INV) with/without a metal layer in the bottom tier is investigated, and then the regime of the thickness T_ILD and dielectric constant ε_r of the inter-layer distance (ILD), the doping concentration N_d (N_a), and length L_g of the channel, and the side-wall length L_SW where the stacked FETs are coupled are studied. When N_d (N_a) < 10¹⁶ cm^-3 and L_SW < 20 nm, the threshold voltage shift of the top FET varies almost constantly by the gate voltage of the bottom FET, but when N_d (N_a) > 10¹⁶ cm^-3 or L_SW > 20 nm, the shift decreases and increases, respectively. M3INVs with T_ILD ≥ 50 nm and ε_r ≤ 3.9 can neglect the interaction between the stacked FETs, but when T_ILD or ε_r do not meet the above conditions, the interaction must be taken into consideration.

• 한국실내디자인학회논문집
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• 제15권4호
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• pp.97-105
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• 2006

Richard Meier has earned his recognition by developing his unique design approach and keeping consistency in design concept in museum architecture over the years of his practice. The purpose of this study is finding common characteristics of the exhibition space spatial organization based on actual site visit analysis. This study will mainly focus on the museums Richard Meier designed between 1979, which is the year he started, until 1997 which is the year Getty Museum opened. For the purpose of this study, Museum of Applied Art, Frankfurt(1979-85), High Museum of Art, Atlanta(1980-83), Museum of Contemporary Art, Barcelona(1987-95), and The J.Paul Getty Museum(1984-1997) have been selected for analysis. This study will reveal fundamental characteristics of Richard Meier's architectural philosophy through his early residential projects and give background information of the 'white architecture' Close analysis will continue by reviewing four museums selected specifically for this study and focus more from the point of issues such as; 1)applying various axis in space programming, 2)symbolic significance of exhibition space, 3)hierarchy of each space, 4)design elements and characteristics of the exhibition space. Furthermore, quantitative research on exhibition space organization will be done by Space Syntax theory method. The result of the study will be a significant data in designing a modern museum.

• Transactions on Electrical and Electronic Materials
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• 제1권3호
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• pp.23-28
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• 2000

A block-oxide layer was formed on the surface of Cu-based leadframe by chamical oxidation method in order to enhance the adhesion strength between Cu-based leadframe and epoxy molding compound (EMC) Using sandwiched double cantilever beam (SDCB) specimens, the adesion strength was measured in terms of interfacial fracture toughness, G$\sub$IC//Results showed that the black-oxide layer was composed of two kinds of layers: pebble-like Cu$_2$O layer and acicular CuO layer, At the initial stage of oxidation the Cu$_2$O layer was preferentially formed and thickened up to around 200 nm whithin 1 minute of the oxidation time. Then the CuO layer started to from atop of the Cu$_2$O layer and thickened up to around 1300 nm until 20 minutes. As soon as the CuO layer formed, the thickness of Cu$_2$O layer began to reduce and finally reached to around 150 nm. The pre-cleaned and the Cu$_2$O coated leadframes showed almost no adhesion of EMC, however, as the CuO precipitates appeared and became continuous, G$\sub$IC/ increased up to around 80 J/㎡. Further oxidation raised G$\sub$IC/ up. to around 100 J/㎡.

• 한국식품저장유통학회지
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• 제11권1호
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• pp.12-16
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• 2004

본 연구는 우리나라 대표적인 전통식품중의 하나인 유과를 미국 현지인들에게 수출하고자 포장, 디자인 등을 개선하여 미국인 262명에게 2002년 8-9월 중 기호도 조사를 실시한 것으로써 조사대상자의 성별분포는 남자 45.8％, 여자 54.2％, 연령분포는 10대 41.6％, 20대 58.4％, 인종분포는 백인이 84.0％, 흑인은 8.8％, 히스페닉인은 7.1％이었다. 유과의 포장상태는 전체 응답자중 82.7％는 만족하였으며 포장디자인은 22.0％가 매우 만족하고 54.4％가 만족하는 것으로 나타났으며 인쇄는 69.7％ 이상이 만족한 것으로 나타났다. 그러나 조직감은 48.5％로 만족정도가 다른 항목에 비해 낮았지만 맛과 함께 평가된 향미의 항목에서는 만족도가 60.9％로 상승하였음을 알 수 있었으며 유과에 대한 전반전인 기호도는 92.7％로 응답자 대부분의 기호에 적합하다고 답하였다.

• Clinical and Experimental Pediatrics
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• 제64권6호
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• pp.251-259
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• 2021

Psychogenic nonepileptic seizures (PNES) is a neuropsychiatric condition that causes a transient alteration of consciousness and loss of self-control. PNES, which occur in vulnerable individuals who often have experienced trauma and are precipitated by overwhelming circumstances, are a body's expression of a distressed mind, a cry for help. PNES are misunderstood, mistreated, under-recognized, and underdiagnosed. The mind-body dichotomy, an artificial divide between physical and mental health and brain disorders into neurology and psychiatry, contributes to undue delays in the diagnosis and treatment of PNES. One of the major barriers in the effective diagnosis and treatment of PNES is the dissonance caused by different illness perceptions between patients and providers. While patients are bewildered by their experiences of disabling attacks beyond their control or comprehension, providers consider PNES trivial because they are not epileptic seizures and are caused by psychological stress. The belief that patients with PNES are feigning or controlling their symptoms leads to negative attitudes of healthcare providers, which in turn lead to a failure to provide the support and respect that patients with PNES so desperately need and deserve. A biopsychosocial perspective and better understanding of the neurobiology of PNES may help bridge this great divide between brain and behavior and improve our interaction with patients, thereby improving prognosis. Knowledge of dysregulated stress hormones, autonomic nervous system dysfunction, and altered brain connectivity in PNES will better prepare providers to communicate with patients how intangible emotional stressors could cause tangible involuntary movements and altered awareness.

• 대한의용생체공학회:의공학회지
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• 제27권2호
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• pp.53-58
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• 2006

In this study, transverse relaxation time (T2) measurement and the evaluation of the characteristics of the spectral peak related to stomach tissue metabolites were performed using ex vivo proton magnetic resonance spectroscopic imaging (MRSI) at 1.5-T MRI/S instruments. Thirty-two gastric tissues resected from 12 patients during gastric cancer surgery, of which 19 were normal tissue and 13 were cancerous tissue, were used to measure the $T_2$ of the magnetic resonance spectroscopy (MRS) peaks. The volume of interest data results from the MRSI measurements were extracted from the proper muscle (MUS) layer and the composite mucosa/submucosa (MC/SMC) layer and were statistically analyzed. MR spectra were acquired using the chemical shift imaging (CSI) point resolved spectroscopy (CSI-PRESS) technique with the parameters of pulse repetition time (TR) and echo times (TE) TR/(TE1,TE2)=1500 msec/(35 msec, 144 msec), matrix $size=24{\times}24$, NA=1, and voxel $size=2.2{\times}2.2{\times}4mm^3$. In conclusion, the measured $T_2$ of the metabolite peaks, such as choline (3.21ppm) and lipid (1.33ppm), were significantly decreased (p<0.01 and p<0.05, respectively) in the cancerous stomach tissue.