• 한국정보과학회논문지:소프트웨어및응용
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• 제35권9호
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• pp.547-553
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• 2008

본 논문에서는 2 단계 서류 레이아웃 분할 방법을 제안한다. 서류 분할의 1 차 단계는 top-down 계열의 영역 추출로서 모폴로지 기반의 거리 함수를 사용하여 주어진 영상 데이타를 사각형 영역들로 분할한다. 거리 사상 함수를 통한 예비 결과는 성능 개선을 위한 2 차 단계의 입력 변수로 작용한다. 서류 분할의 2차 단계로서 기계 학습 이론을 적용한다. 통계 모델을 따르는 RBF 신경망을 선택하였고, 은닉 층의 설계를 위해 코호넨 네트워크의 자기 조직화 성격을 활용한 데이타 군집화 기법을 기반으로 하였다. 본 논문에서는 300개의 영상에서 추출된 영역 데이타를 통해 학습된 신경망이 1차 단계에서 도출된 예비 결과를 개선함을 연구 결과로 제시하였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.430.1-430.1
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• 2014

According to advanced nanotechnology in the field of biomedical engineering, many studies of the interaction between topography of surfaces and cellular responses have been focused on nanostructure. In order to investigate this interaction, it is essential to make well-controlled nanostructures. Electron beam lithography (EBL) have been considered the most typical processes to fabricate and control nano-scale patterns. In this work, $TiO_2$ nanowire array was fabricated with hybrid process (top-down and bottom-up processes). Nanodot arrays were patterned on the substrate by EBL process (top-down). In order to control the spacing between nanodots, we optimized the EBL process using Poly(methyl methacrylate) (PMMA) as an electron beam resist. Metal lift-off was used to transfer the spacing-controlled nanodots as a seed pattern of $TiO_2$ nanowire array. Au or Sn nanodots which play an important role for catalyst using Vapor-Liquid-Solid (VLS) method were patterned on the substrate through the lift-off process. Then, the sample was placed in the tube furnace and heated at the synthesis temperature. After heat treatment, $TiO_2$ nanowire array was fabricated from the nanodots through VLS method (bottom-up). These results of spacing-controlled nanowire arrays will be used to study the interaction between nanostructures and cellular responses in our next steps.

• 인지과학
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• 제10권3호
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• pp.1.1-10
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• 1999

한국어 명사들을 의미별로 분류하여 계층화시킨‘한국어 명사 의미 계층 구조’는, 한국어 문장을 처리할 때 의미 정보를 제공할 수 있는 매우 중요한 것들 중의 하나이다. 본 논문에서는, 국어 사전의 명사에 대한 뜻 풀이말을 이용하여 bottom-up 방식으로‘한국어 명사 의미 계층 구조’를 구축하였다. 본 논문에서 구축한‘한국어 명사 의미계층 구조’는, 트리(tree)가 43개, 중간 노드(node)가 2,443개, 단말 노드(terminal node)가 10,347개이며, 깊이(depth)가 17인 하나의 포리스트(forest)를 이룬다. 이것의 제 1, 2 계층(level 1, 2)에서의 분류 형태는 top-down 방식에 의한 기존의 분류들과 매우 다른 모습인 반면에, 제 3 이하의 계층들은 상당히 객관적이 형태를 이루고 있다.

• Bulletin of the Korean Chemical Society
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• 제35권10호
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• pp.2917-2921
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• 2014

Cerium-activated yttrium aluminate ($Y_3Al_5O_{12}:Ce^{3+}$) exhibiting a garnet structure has been widely utilized in the production of light emitting diodes (LEDs) as a yellow emitting phosphor. The commercialized yttrium aluminum garnet (YAG) phosphor is typically synthesized by a solid-state reaction, which produces irregular shape particles with a size of several tens of micrometers by using the top-down method. To control the shape and size of particles, which had been the primary disadvantage of top-down synthetic methods, we synthesized YAG:Ce nanoparticles with a diameter of 500 nm using a coprecipitation method under the atmospheric pressure without the use of template or special equipment. The precursor particles were formed by refluxing an aqueous solution of the nitrate salts of Y, Al, and Ce, urea, and polyvinylpyrrolidone (55 K) at $100^{\circ}C$ for 12 h. YAG:Ce nanoparticles were formed by the calcination of precursor particles at $1100^{\circ}C$ for 10 h under atmospheric conditions. The phase identification, microstructure, and photoluminescent properties of the products were evaluated by X-ray powder diffraction, scanning electron microscopy, absorption spectrum and photoluminescence analyses.

• Childhood Kidney Diseases
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• 제21권2호
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• pp.114-120
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• 2017

Purpose: The aim of this study was to determine the clinical characteristics, frequency of renal abnormalities and benefits of a top-down approach in children with their first febrile urinary tract infection (UTI). Methods: We reviewed 308 patients retrospectively who were admitted to Yeungnam University Hospital and were treated for their first febrile UTI from February 2006 to December 2013. We performed a comparative analysis of laboratory findings and results of imaging techniques including a Tc-99m dimercaptosuccinic acid (DMSA) renal scan. Results: Among the patients, 69% (213/308) were males, and 90% (277/308) had their first UTI episode during infancy. A DMSA renal scan was performed on all patients, and showed positive findings in 60% (184/308) of cases. Laboratory indices of inflammation were significantly higher in the DMSA-positive group (P< 0.05). There was a statistically significant difference in the age distribution between the two groups. In the DMSA-positive group, 165 patients underwent voiding cystourethrography (VCUG), and 58 (35%) cases demonstrated vesicoureteral reflux. In total, 110 patients in the DMSA-positive group, underwent repeat scanning at 6 months; 33 children (30%) demonstrated static scarring, but 77 (70%) had improved completely. The concordance of the ultrasonography (US) and VCUG was low. Older patients had more renal scarring. Conclusion: DMSA is a sensitive method for assessing the severity of inflammation and kidney injury. However, the ability of US to predict renal parenchymal damage was limited. A top-down approach in children with their first febrile UTI showed significant value.

• Asian Pacific Journal of Cancer Prevention
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• 제13권5호
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• pp.2419-2423
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• 2012

Context: Genuine community participation does not denote taking part in an action planned by health care professionals in a medical or top-down approach. Further, community participation and health education on breast cancer prevention are not similar to other activities incorporated in primary health care services in Iran. Objective: To propose a model that provides a methodological tool to increase women's participation in the decision making process towards breast cancer prevention. To address this, an evaluation framework was developed that includes a typology of community participation approaches (models) in health, as well as five levels of participation in health programs proposed by Rifkin (1985&1991). Method: This model explains the community participation approaches in breast cancer prevention in Iran. In a 'medical approach', participation occurs in the form of women's adherence to mammography recommendations. As a 'health services approach', women get the benefits of a health project or participate in the available program activities related to breast cancer prevention. The model provides the five levels of participation in health programs along with the 'health services approach' and explains how to implement those levels for women's participation in available breast cancer prevention programs at the local level. Conclusion: It is hoped that a focus on the 'medical approach' (top-down) and the 'health services approach' (top-down) will bring sustainable changes in breast cancer prevention and will consequently produce the 'community development approach' (bottom-up). This could be achieved using a comprehensive approach to breast cancer prevention by combining the individual and community strategies in designing an intervention program for breast cancer prevention.

• 정보통신설비학회논문지
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• 제10권1호
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• pp.33-39
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• 2011

This paper considers a performance analysis of set-top box (STB) power saving schemes. STB converts the signal into content which is then displayed on the television (TV) screen, and there are typically two operation modes: on mode and stand-by mode. The total energy consumption (TEC), a typical measure of power consumption of STB, is defined by the sum of power consumption in each mode. Recently there are some works of STB power saving schemes that transit STB operation modes efficiently, and the mode transition time point of those schemes can be different. Thus it is required to develop a performance evaluation method that reflects mode transition time points of each scheme to get TEC correctly. This paper proposes a performance evaluation method for STB power consumption using Poisson process to consider the mode transition time point. By modeling STB mode transitions as events of Poisson process, the average time duration of STB mode is computed and accordingly the effect of power saving is evaluated. The performance evaluation result shows that the proposed method achieves 1 to 19% improvement in power consumption compared with a conventional performance evaluation method.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.869-887
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• 2008

Coffer dam for tunnel type spillway in inflow section of Dae-am dam was originally planned as 2 lines sheet piles with Water Zet method. But, the result of pilot test was caused of some problems that vibration during installation of pile could pollute water and water leakage could the lower part. So, sheet piles was not satisfactory for faculty of coffer dam. Structural instability of sheet pile system need to reinforcement. Characteristic of Dae-am dam was small reservoir capacity but wide drainage area, of which it was judgment that security of leakage and stability was difficult during excavation of inlet part. So, we consider that water curtain method utilized with in site pouring concrete pile method was designed at weir part of spillway. We were known about basement rock that geological boring was carried out in weir part. After taking a deep consideration, PRD method was accepted as a new method. Concrete pile by PRD was installed to below country rock. CJM method was carried out with PRD. After making concrete wall using Top-down method, earth anchors were installed for supporting it. According to the result of numerical analysis, as water level rises, wall is stable.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.2844-2851
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• 2011

The purpose of this study is to set up an acoustic prediction technique and to perform the IL test of scale down noise reducing device for the development of the noise reducing device as the development of 400km/h class high speed train. First of all, the IL prediction of noise reducing device was performed with the 2D BEM method. And the noise test of scale down noise reducing device in anechoic chamber was performed for the verification of acoustic prediction technique and IL performance evaluation. As the results, the acoustic prediction technique for the development of noise reducing device was verified because the averaged IL difference between prediction and test is in 2dB(A). And the measured IL value of noise reducing device is less than 2dB(A), and additional IL with polyester absorption material is increased about 0.5dB(A).

• 한국정보과학회논문지:데이타베이스
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• 제29권5호
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• pp.367-380
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• 2002

최근 공간 데이타 분석, 영상 분석 등과 같은 대용량 데이타를 관리하는 다양한 응용 업무들이 증가함에 따라, 대용량의 데이타베이스를 위한 클러스터링 기법이 많이 연구되고 있다. 그 중에서도 계층 클러스터링 기법은 데이타베이스의 계층 분할을 표현하는 계층 트리를 생성하고 이를 이용하여 효율적인 클러스터링을 수행하는 방법으로서, 지금까지는 주로 트리를 하위 계층으로부터 상위 계층으로 생성해 가는 상향식(bottom-up) 계층 클러스터링 기법들이 연구되었다. 이러한 상향식 클러스터링 방법은 트리를 생성하기 위하여 전체 데이타베이스를 한 번 이상 액세스하여야 할 뿐만 아니라, 하위 계층에서부터 검색을 시작하기 때문에 트리의 많은 부분을 검색하여야 하는 문제점이 있다. 본 논문에서는 대부분의 데이타베이스 응용에서 이미 유지하고 있는 다차원 색인을 이용하여 클러스터링을 수행하는 새로운 하향식(top-down) 계층 클러스터링 기법을 제안한다. 일반적으로 다차원 색인에서는 가까운 객체들이 동일한 (혹은 인접한) 페이지에 저장될 가능성이 큰 클러스터링 성질을 가진다. 이러한 다차원 색인의 클러스터링 성질을 사용하면 각 객체들간의 거리를 일일이 계산하지 않고도 이웃한 객체들을 식별할 수 있다. 우선 객체들의 밀도에 기반하여 클러스터를 정형적으로 정의한다. 이를 위하여, 객체를 포함하는 영역의 밀도를 이용한 영역 대조 분할(region contrast partition) 개념을 사용한다. 또, 클러스터링 알고리즘에서의 빠른 검색을 위하여 분기 한정(branch-and-bound) 알고리즘을 사용하며, 여기서의 한계값(bound)을 제안하고 이의 정확성을 이론적으로 증명한다. 실험 결과, 제안한 방법은 상향식 계층 클러스터링 방법인 BIRCH와 비교하여, 정확성 측면에서 우수하거나 유사한 것으로 나타났으며, 데이타 페이지 액세스 횟수를 데이타베이스 크기에 따라 최고 26～187배까지 감소시킨 것으로 나타났다. 이 같은 결과로 볼 때, 제안한 방법은 대용량 데이타베이스에서의 클러스터링 성능을 크게 향상시키는 기법으로서, 일반 데이타베이스 응용에 실용적으로 적용 가능하다고 판단된다.