• Annual Conference of KIPS
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• 2002.11c
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• pp.1859-1862
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• 2002

비공유 데이터베이스 클러스터는 그 구조의 특성 상 동적인 질의 패턴의 변화, 특정 데이터에 대한 질의 집중에 의한 부하 불균형 및 집중, 사용자 증가에 의한 처리량 한계 등의 문제가 발생한다. 이러한 문제를 해결하기 위해 데이터베이스 클러스터는 최근에 제안된 온-라인 확장기법을 사용하며, 이 기법은 데이터 베이스의 확장성에 의해 큰 영향을 받는다. 일반적으로 클러스터 시스템에서 사용되는 데이터 분할 기법에는 키 값의 순서대로 분할하는 라운드-로빈 분할 기법, 해쉬 함수를 이용해 데이터를 분할하는 해쉬 분할 기법, 범위에 따라 각 노드에 데이터를 분할하는 범위 분할기법, 그리고 조건식에 따라 데이터를 분할하는 조건식 분할 기법이 있다. 본 논문에서는 이 네 가지 분할 기법의 특성을 정리하고, 비공유 데이터베이스 클러스터에서 확장성에 있어서 우수한 분할 기법을 각 분할 기법의 성능평가를 통해 얻는다. 성능평가에서는 각각의 분한 기법을 평가하기 위해 확장 시 발생되는 이동 데이터의 크기, 질의처리에 대한 영향, CPU 사용률, 그리고 온-라인 확장기법의 수행 시 발생되는 특성에 대한 영향을 분석하며, 얻어진 결과를 토대로 비공유 데이터베이스 클러스터에서 가장 적합하면서도 온-라인 확장 기법적용을 위해 확장성이 우수한 데이터 분할기법을 찾는다.

• Journal of Broadcast Engineering
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• v.22 no.1
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• pp.42-50
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• 2017

A Bit-depth expansion is a method to increase the number of bit. It is getting important as the needs of HDR (High Dynamic Range) display or resolution of display have been increased because the level of luminance or expressiveness of color is proportional to the number of bit in the display. In this paper, we present effective bit-depth expansion algorithm for conventional standard 8 bit-depth content to display in high bit-depth device (10 bits). Proposed method shows better result comparing with recently developed methods in quantitative (PSNR) with low complexity. The proposed method shows 1db higher in PSNR measurement with 40 times faster in computational time.

• Journal of Biomedical Engineering Research
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• v.22 no.1
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• pp.59-68
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• 2001

유체-고체 상호작용을 고려하여 다양한 복부대동맥류 모델에 대해서 맥동유동 및 구조를 동시에 해석하였다. 동맥류의 확장부 크기와 혈관벽 두께에 따라서 총 여덟 개의 축대칭 동맥류 모델을 선정하였다. 유한체적법 및 압력기반의 유한차분법을 이용하여 유동을 해석하였으며, 유한요소법을 이용하여 구조해석을 수행하였다. 동맥류의 확장부위가 클수록 최대응력은 최대확장부위와 변곡점에 해당하는 동맥류의 입구 및 출구 부분에 집중되었으며, Von Mises 응력은 최대확장부위 뿐만 아니라 동맥류의 근위부와 원위부($\pm$1D)에서도 현저하게 증가하였다. 또한 더욱 확장된 모델일수록 혈관벽은 직경방향의 변위보다 축방향의 변위가 지배적이었으며, 동맥류 원위부보다 근위부에서 큰 축방향 변위를 나타냈다. 동맥류 입구부의 미약한 와류는 한 주기동안 그 크기와 강도를 더해가며 동맥류 원외부로 이동하였고, 동맥류의 내부 유동은 압력차이가 감소하는 기간동안 더 큰 영향을 받았다. 확장정도가 심할수록 동맥류 내부에 더 크고 강한 와류가 관찰되었다. 압력차이가 최소가 된 직후 동맥류의 근위부와 원위부동맥 벽 근처에서의 역방향 유동이 관찰되었다. 대체로 혈관벽 두께가 감소한 모델과 더욱 확장된 모델일수록 벽전달률은 감소하였다. 혈관벽의 탄성에 의하여 압력차이와 벽전달률 사이에 위상차가 존재함이 확인되었다. 유체-고체의 상호작용을 고려한 연구는 다른 심혈관계를 이해하는데도 매우 유익할 것으로 생각된다.

• The Journal of the Acoustical Society of Korea
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• v.30 no.4
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• pp.190-196
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• 2011

Bandwidth extension is a technique to improve speech quality and intelligibility, extending from 300-3400 Hz narrowband speech to 50-7000 Hz wideband speech. This paper designs an artificial bandwidth extension (ABE) module embedded in the AMR (adaptive multi-rate) decoder, reducing LPC/LSP analysis and algorithm delay of the ABE module. We also introduce a fast search codebook mapping method for ABE, and design a low power BWE technique based on the AMR decoder. The proposed ABE method reduces the computational complexity and the algorithm delay, respectively, by 28 % and 20 msec, compared to the traditional DTE (decode then extend) method. We also introduce a weighted classified codebook mapping method for constructing the spectral envelope of the wideband speech signal.

• The korean journal of orthodontics
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• v.29 no.3 s.74
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• pp.375-381
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• 1999

The purpose of this study was to evaluate whether the basal bone of maxilla was expanded transversely by rapid palatal expansion through the posteroanterior cephalome- tric analysis. Thirty patients with the maxillary deficiency were utilized in this study. The posteroanterior cephalometric X-ray film were taken twice, before and after rapid palatal expansion. logram The obtained results were as follows; 1. There was a significant increase of the maxillary width by rapid palatal expansion in male and female. (P<0.001) 2. There was no significant difference between the male and female in the expansion of the maxillary width by rapid palatal expansion. 3. There was a significant increase of the maxillary width by rapid palatal expansion in the both of before and after the puberty. 4. There was no significant difference between before and after the puberty in the expansion of the maxillary width by rapid palatal expansion.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.2
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• pp.35-40
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• 2003

Cold expansion method is an effective process to retard the crack initiation at a hole and to improve fatigue life by developing the compressive residual stress around the hole. Several researches have been treated for the crack propagating toward a hole around which the residual stress by cold expansion exists. The objective of this paper is to evaluate the fatigue characteristics under the residual stress by cold expansion. Fatigue tests are performed for the plate with a central hole to which cold expansion has been applied, and the effects of the residual stress on the fatigue life are evaluated. Also the fatigue crack growth tests are conducted for the CT specimen in which the residual stress by cold expansion has been generated. The change of fatigue crack growth characteristics by the residual stress is investigated and the effects of cold expansion ratio are evaluated.

• Korean journal of communication and information
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• v.27
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• pp.183-212
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• 2004

Mobile phone media have extended the terrain of human communication. Starting from the notion of McLuhan, this study suggests that the extension of human communication is a concept of multiple dimension, such as 'extension of function' and 'extension of ego' Mobile phone speed the pare and efficiency of life, but also allow more flexibility at business and professional levels as well as family and personal life. On the other hand, mobile phone is also conceived as a personality kit, that is as a symbol of user's identity. So we ran classify the mobile phone users as a typology of motivation. Group I, entitled 'hyper-coordination', has high instrumental and high expressive motivation. Group II(='instrumental') is high instrumental but low expressive. Group III(='expressive') is low instrumental and high expressive, and Group IV(='minimal') is low in both instrumentality and expressiveness of mobile phone use. Then would the hyper-coordination group have different usage pattern with the other groups? A sample of 482 university students completed survey questionnaire. , which states hyper-coordination group would most frequently make calls and text, and have largest extensity and variety of usage, is supported statistically. states that hyper-coordination group would have larger and deeper social network than the other groups. This hypothesis is also supported with statistics.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.2
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• pp.1054-1063
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• 2015

This study is to verify the effect of similarity of expanded-product, brand concepts of parent-brands and implicit theory of customers on the brand-extension evaluation, in order to reduce the risk of brand extension. First, this research documents how the similarity between the parent-brands and expanded-products affect brand-extension evaluations as a main effect variable. Second, this study examines the moderating effect of the brand concepts of parent-brands on the brand-extension evaluation. Third, this research documents how implicit theories regarding personality affect consumer evaluations about the brand-extension. The study assumes and tests that consumers in the group of incremental theorists are more accepting of brand-extensions than consumers in the group of entity theorists. The result figures out the implicit theory customers has some moderating effect on the evaluations, yet the direction of the effects is contrary to expectations.

• Journal of Korea Water Resources Association
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• v.48 no.3
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• pp.209-220
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• 2015

In this study, the effects of changed environment on spatial extension of flood discharge data which is generating discharge data at ungauged watersheds. Especially, effects of dams on spatial extensions of flood discharge data and on natural flow generation were studied. This is somehow an intial trial of flood discharge data generation for heterogeneous watersheds because of dam installation. Data extensions have been performed based on the flood discharge data from YeoJoo water gauge station located on the Nam-Han River. For the evaluation of flood discharge data spatial extension under dam effects and producing natural flow, 41 flood events associated with YeoJoo water gauge station were selected from 1986 to 2010. When flood discharge data were extended based on YeoJoo water gauge station, 77% of selected flood events were over the satisfaction ranges (NSE>0.5) of Nash-Sutcliffe Efficiency for model validation. Extended flood discharge data at Yangpyung has 0.84 NSE obtained from spatial data extension based on YeoJoo water gauge station. Generated natural flow at YeoJoo was influenced strongly by Chungju Dam which has larger effects on streamflow at YeoJoo than Hoangsung Dam. Observed peak discharges after the 1986 of Chungju Dam installation were smaller than those of the obtained natural flow. Through these results, spatial extension of flood discharge data with installed dams works efficiently for ungauged watersheds and natural flow can be generated using extended flood discharge data.

• Journal of Service Research and Studies
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• v.12 no.4
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• pp.50-71
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• 2022

After the declaration of the Covid-19 pandemic impacted most of the industries resulting economic fallout. Firms sought for solutions of governments regulations to prevent spread of infectious diseases. This led to demand rise of digital layer and spectrums of virtual reality. Replacing the reality in to virtual and interactions with the digital contents by augmented reality, the consequences were decrement of human-to-human contact. Concerns of Covid-19 and public interests of digital solutions has led to significant amounts of research and developments of Virtual/Augment Reality resulted to driven up new terms of extended reality. However, the uses in industries and the characteristics of the extended reality are currently not defined. In this paper the goal is to define and classify the uses and characteristics of extended reality based on previous researches suggested by research institute. By developing a new classification models of extended realities core technology, uses of industries and utility to analyze trends of extended reality. Two separate classification models of uses of industries and utility will be used as a tool by creating a linkage matrix. The x-axis is divided by utiliy classification model of extended reality. The y-axis are divided into classification model of uses in industries. This matrix will be used as a tool to present a guideline for industry-utility development where extended reality can be served as a service