• Journal of KIISE:Information Networking
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• v.28 no.4
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• pp.611-620
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• 2001

To meet the requirements of reliable service for various applications, a Reliable Multicast Transport Protocol should be implemented over IP Multicast where currently best-effort service is provided. Among the current researches, hierarchical tree-based mechanism has been proposed and actively studied. This mechanism is known to provide high scalability as well as reliability, but needs an additional tree configuring mechanism for building an efficient logical tree in transport layer. Bottom-up approach has been used for creating such a tree. This method has benefits from parallel tree construction for receivers, while it has some drawbacks such that it does not guarantee a loop-free tree and brings heavy message overhead during tree creation process. Therefore, this paper proposes a top-down based mechanism for constructing a control tree, which can guarantee loop-freeness by step-wise mannered tree building. From experimental simulations, it shows that the proposed mechanism has less message overhead. It is recommended that the bottom-up and the proposed top-down will be selectively used in real networks, according to the requirements of the concerned multicast applications.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.3-3
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• 2008

21 세기 제 3의 산업혁명을 가져올 것으로 기대되는 나노기술(NT), 정보기술(IT), 바이오기술(BT)은 전 세계 과학자들의 마음을 사로잡고 있다. 이 가운데 나노기술은 전자산업에 응용시 그 기대효과는 우리가 상상하는 이상의 것이라 예상하고 있다. 나노기술에 특히 관심을 가지는 이유는 물질이 마이크로미터 크기로 작아져도 벌크 물질의 물리적 특성이 그대로 유지되지만, 나노미터 크기가 되면서 우리가 경험하지 못했던 새로운 물리적 특성들이 발현되기 때문이다. 그 특성에는 양자구속효과, Hall-Petch 효과, 자기효과 등이 있다. 나노기술의 구현은 양자점과 같은 영차원 나노입자, 나노와이어, 나노막대, 나노리본 등과 같은 직경이 100nm 이하의 일차원 구조의 나노물질 및 나노박막과 기타 100nm 이하의 나노구조물들이 사용된다. 현재 일차원 구조를 이용한 전자디바이스화 연구는 결정성장을 정확하게 조절하는 합성기술 합성된 일차원 나노물질의 물리적 특성을 지배하는 각종 파라미터들과 물리적 특성들과의 상관관계 정립, 나노와이어를 이용한 Bottom-up 방식에 의한 조립기술 확보를 위해 활발히 진행 중이다. 하지만 나노구조의 특성을 확인하는 형태의 연구일 뿐, 실제 디바이스화에는 여전히 많은 과제를 안고 있다. 본 연구에서는 산화아연을 기반으로 한 고품위 능동형 산화물 나노구조의 다양한 성장방법 및 물성 평가에 대해 연구하였다. 성장장비로는 MOCVD와 스퍼터링을 이용하여 대면적 균일 성장을 이룰 수 있었다. 특히 실제 광전소자에 응용요구에 알맞은 Bottom-up 방식에 의한 수직성장 기술, 길이/직경 비 향상 기술, 결정성 향상 기술, 저온성장 기술, Dimension 조절 기술 Interfacial layer 제거 기술 등을 중점적으로 연구하였다. Dimension 조절 기술로 p-Si 기판위에 성장된 나노 LED에서는 밝은 emission을 관찰하였으며, 세계에서 최초로 스퍼터링을 이용하여 4인치 웨이퍼에 대면적 수직 성장하였다. 최근에는 선택적 삼원계 씨앗층을 이용한 길이/직경 비가 매우 향상된 MgZnO 나노와이어를 Interfacial layer 없이 수직으로 성장하여 산화물 전계방출 에미터로서의 가능성을 확인하였다.

• Journal of Agricultural Extension & Community Development
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• v.24 no.2
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• pp.143-154
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• 2017

Saemaul Undong (SM U) initiated in Korea in the 1970's is widely acknowledged as a successful model for rural community development, despite its limitations. This paper investigates the success factors of the SMU model and the lessons thereof for Sam Sang Model of Lao PDR, which appears ineffective over the years. Results show that land reforms, social ties among villages, strong institutional support and leadership and incentive system as well as "top-down" and "bottom-up" development approaches are among the factors that significantly contributed to the success of the SMU. However, rural development program would not be effective if residents are unwilling to participate. Therefore, to successfully achieve rural community development in Lao PDR, the government should through the Sam Sang model employ top-down and bottom-up approaches to enhance local participation and address the exact needs of the local people.

• Journal of Korean Society for Atmospheric Environment
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• v.30 no.2
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• pp.161-174
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• 2014

The methodology report '2006 IPCC Guidelines for National Greenhouse Gas Inventories' shows higher tier method can be a good practice, which uses country-specific or plant-specific data when calculating greenhouse gas emissions by country. We review the methodology report to present principles of using plant-level data and also examine examples of using plant-level data in chemical and metal industry in 20 countries for the purpose of quality improvement of national greenhouse gas inventories. We propose that Korea consider utilizing plant-level data, as reported according to 'Greenhouse gas and Energy Target Management Scheme', in the following order as a preference. First, the data can be utilized for quality control of Korea's own parameters, when Tier 2 method is adopted and bottom-up approach is not applicable. Second, both plant-level data and IPCC default data can be used together, combining Tier 1 method with Tier 3 method. Third, we can also use acquired plant-level data and country specific parameters, combining Tier 2 method with Tier 3 method. Fourth, if the plant-level data involves all categories of emissions and the data is proven to be representative, we can apply Tier 3 method. In this case, we still need to examine the data to check its reliability by a consistent framework, including appropriate quality control.

• Korean Journal of Construction Engineering and Management
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• v.10 no.2
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• pp.3-13
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• 2009

Knowledge management (KM) has been considered to be an effective means of learning from past projects to effect continuous performance improvement in the construction industry. Despite the growing importance of KM in the construction industry, the usage and effectiveness of IT tools for implementing KM are limited to some extent. Case studies of current KM practices in Korean construction sectors revealed that the chief causes of this problem are the top-down approach of the current practices. To address this challenging issue, this research proposes bottom-up approach, which motivates knowledge creation by shifting the ownership of contents, and facilitates effective reuse of knowledge by providing rich contextual information.

• Journal of the Korean Institute of Rural Architecture
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• v.13 no.3
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• pp.45-52
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• 2011

Development of rural village in the agriculture, forestry and fishing community development nongsan eoeopin samuijil improve and promote the special law, from 2004 to 2017, based on the 1000 National differentiated rural areas to maintain the "ness, and in rural areas to build basic infrastructure, a complex life-and characteristics of the rural development and participate in the preliminary planning stages and led from the bottom-up development project in the village during the project implementation period proposed by the residents of the project is a business. This study, Jeonnam local rural residents of the village to participate in Development Business to help identify and analyze the problems derive satisfaction and improve the direction and purpose it is proposed to activate. To enable business juminchamyeohyeong city committee of the doctors and residents rally the support of the local government system, including voluntary participation and bottom-up business is important for the recognition of conversions. For bottom-up business people recognize and understand the transition to a new seonjinji tour, the continued education of residents and leading to the village to town to put all my energy into education, including the leader of the residents of the town desperately needs strengthening and capacity. In addition, town residents also important for the development, awareness and active participation, residents and the local government, and established a partnership with a group of experts monitoring implementation of the main city in the shape of lack of food is the most important part is fill.

• Journal of Digital Convergence
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• v.13 no.1
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• pp.227-235
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• 2015

Big data analysis is a means of organizational problem solving. For an effective problem solving, approaches to problem solving should take into account the factors such as characteristics of problem, types and availability of data, data analytic capability, and technical capability. In this article we propose three approaches: logical top-down, data driven bottom-up, and prototyping for overcoming undefined problem circumstances. In particular we look into the relationship of creative problem solving with the bottom-up approach. Based on the organizational data governance and data analytic capability, we also derive strategic issues concerning the sourcing of big data analysis.

• Geomechanics and Engineering
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• v.13 no.6
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• pp.1011-1025
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• 2017

The geological conditions surrounding the Jijiapo Tunnel of the Three Gorges Fanba Highway project in Hubei Province are very complex. In this paper, a 3-D physical model was carried out to study the evolution process of filling-type fracture water inrush and mud gush based on the conditions of the section located between 16.040 km and 16.042 km of the Jijiapo Tunnel. The 3-D physical model was conducted to clarify the effect of the self-weight of the groundwater level and tunnel excavation during water inrush and mud gush. The results of the displacement, stress and seepage pressure of fracture and surrounding rock in the physical model were analyzed. In the physical model the results of the model test show that the rock displacement suddenly jumped after sustainable growth, rock stress and rock seepage suddenly decreased after continuous growth before water inrushing. Once water inrush occured, internal displacement of filler increased successively from bottom up, stress and seepage pressure of filler droped successively from bottom up, which presented as water inrush and mud gush of filling-type fracture was a evolving process from bottom up. The numerical study was compared with the model test to demonstrate the effectiveness and accuracy of the results of the model test.

• Journal of Korean language education
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• v.29 no.1
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• pp.109-137
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• 2018

The purpose of teacher education is to improve the professionalism of teachers above the current level. The type of teacher education to improve the professionalism of experienced teachers is broadly divided into top-down education and bottom-up education. So far, studies on top-down education were commonly conducted in the field of Korean language education. However, there has been an increasing number of studies emphasizing the need for bottom-up education, driven by the voluntary participation of teachers in recent years. The purpose of this study is to suggest the direction of reflective teacher education for experienced Korean language teachers. For this purpose, a survey was conducted of 71 Korean language teachers who had more than 5 years of experience. The contents of the survey consisted of opinions regarding existing teacher education, the need for reflective teacher education, and the perception of teaching professionalism. The results showed that experienced Korean language teachers had a positive perception of the existing teacher re-education experience. Also, 91% of the respondents said they intend to participate in the reflective teacher education program. In particular, respondents showed high demands for 'peer coaching', 'peer observation', and 'teaching portfolios' among reflective teacher education programs. Lastly, many respondents selected 'development and utilization of teaching materials', 'encouraging learner's utterances', and 'leading learner's interest and motivation' as sub-elements of teaching professionalism that they wish to improve through teacher re-education.

• Journal of the Korean Geotechnical Society
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• v.37 no.3
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• pp.43-50
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• 2021

On the construction of new roads, the cut slope is inevitable and thus has been widely applied in the mountainous area. Particularly, the retaining wall with the precast concrete panel is often selected for its higher stability and mostly constructed in bottom-up method. However, the bottom-up method results in steeper slope as 1:0.05 before constructiong retaining wall and thus causes poor compaction at backfill which may induce instability during or after the construction. To overcome this problem, precast concrete panel retaining wall was attached in-situ ground (so called top-down). This paper presents the evaluation of drainage capacity of top-down method which has impermeable layer between panel and mortar being used to increase the ability of attachment of the precast concrete panel.