• Nuclear Engineering and Technology
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• 제41권1호
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• pp.11-20
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• 2009

Radiation effects on materials are inherently multiscale phenomena in view of the fact that various processes spanning a broad range of time and length scales are involved. A multiscale modeling approach to embrittlement of pressure vessel steels is presented here. The approach includes an investigation of the mechanisms of defect accumulation, microstructure evolution and the corresponding effects on mechanical properties. An understanding of these phenomena is required to predict the behavior of structural materials under irradiation. We used molecular dynamics (MD) simulations at an atomic scale to study the evolution of high-energy displacement cascade reactions. The MD simulations yield quantitative information on primary damage. Using a database of displacement cascades generated by the MD simulations, we can estimate the accumulation of defects over diffusional length and time scales by applying kinetic Monte Carlo simulations. The evolution of the local microstructure under irradiation is responsible for changes in the physical and mechanical properties of materials. Mechanical property changes in irradiated materials are modeled by dislocation dynamics simulations, which simulate a collective motion of dislocations that interact with the defects. In this paper, we present a multi scale modeling methodology that describes reactor pressure vessel embrittlement in a light water reactor environment.

• 한국생산제조학회지
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• 제19권6호
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• pp.847-851
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• 2010

It was attempted to develop an auto part by over molding injection mold that produces precision products in high productivity with use of an eco-friendly TPE substitute material for NBR. NBR is currently used in motor gear cover, one of the key parts in motor module for auto doors. Gear cover is composed of plastics and rubber mostly today, which requires a two (2) step process for production using two presses of different types. A hot press is used at this time for forming the rubber, which has drawback of requiring a rather long forming time of 400 seconds for one forming process. Even though this difficulty is overcome by reducing production time through employment of multi-cavity molds, time for forming process must be shortened for improvement of the productivity eventually, and the existing method of insert injection for products that have been formed with plastic material must be outgrown. In this point of view, over molding injection using TPE has a big advantage. Forming time is shortened to 54 seconds, and working the two (2) processes in series by one (1) press could solve the durability problem caused by deflection of the plastics, not to mention shortening the process time. Enhancement of productivity by almost 80% and improvement in the accuracy of the product could thus be achieved.

• Steel and Composite Structures
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• 제34권4호
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• pp.561-580
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• 2020

Buckling restrained braces (BRBs) were developed as an enhanced alternative to conventional braces by restraining their global buckling, thus allowing development of a stable quasi-symmetric hysteretic response. A wider adoption of buckling restrained braced frames is precluded due to proprietary character of most BRBs and the code requirement for experimental qualification. To overcome these problems, BRBs with capacities corresponding to typical steel multi-storey buildings in Romania were developed and experimentally tested in view of prequalification. In the second part of this paper, a complex nonlinear numerical model for the tested BRBs was developed in the finite element environment Abaqus. The calibration of the numerical model was performed at both component (material models: steel, concrete, unbonding material) and member levels (loading, geometrical imperfections). Geometrically and materially nonlinear analyses including imperfections were performed on buckling restrained braces models under cyclic loading. The calibrated models were further used to perform a parametric study aiming at assessing the influence of the strength of the buckling restraining mechanism, concrete class of the infill material, mechanical properties of steel used for the core, self-weight loading, and frame effect on the cyclic response of buckling restrained braces.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.829-832
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• 2006

The river environments of many streams in korea have been deteriorate through the rapid industrialization and urbanization since the 1960s. In korea, on the other hand, much efforts on the research and project have been made for the restoration of the deteriorated streams to close-to-nature. in order to restore the deteriorated streams, therefore, it is necessary to investigate such advanced technologies and materials. In view of this requirement, various research paths are being taken focusing on coarse aggregates to make multi-functional porous concrete having continuous voids so as to improve water and air permeability, acoustic absorption, water purification, and applicability to vegetation. The Purpose of this study is to investigate the method for recovery of the environment in the streams area using porous concrete painting block. the P.O.C block applies for test in the kyungan-cheon have been monitored planting during six month. after 6 months, plant grows flourishing and reconstructed in state such as nature rivers.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 B
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• pp.1193-1195
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• 2004

Ozone gas is one of the strongest oxidizing and bleaching agents which leave no residues harmful to the global environment. In recent years, the ozone generator has been widely utilized, However, it has been known that a broader application of ozone is hindered primarily because of its low efficiency of generation. Thus, it is more indispensable to improve actual system efficiency of the silent discharge type ozonizer using high frequency inverter. This paper presents a multi level resonant ozone power regulation by association of high frequency transformers and full bridge invert. And proposed resonant inverter system can generate continuous output voltage. can control linearly quantity of ozone gas. This invert that add PWM forms within square forms of output voltage about one level range. The power regulation characteristics and operating performances of silent discharge (SD)type ozone generating tube load driven by this load proposed inverter using FET modules are illustrated from a practical point of view, which can operate under stable conditions of basic level and PWM hybrid control strategy implemented DSP(2406). The effectoveness of propsed invert type ozonizer is proved by experiment results.

• 디지털포렌식연구
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• 제12권3호
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• pp.55-70
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• 2018

모바일 기기의 다양화, 웹기술의 발달, 클라우드의 대중화로 기기에 종속되지 않는 인터넷 중심의 웹OS가 필요하게 되었다. 크롬북은 구글에서 개발한 웹OS가 탑재된 컨버터블 노트북 형태의 모바일 기기이다. 이런 웹OS 모바일 기기는 동일기기 다중 사용자의 특성과 클라우드를 통한 자료의 저장과 공유의 장점도 있지만, 보안성이 우수하고 손쉬운 증거인멸이 가능하여 포렌식 관점에서 증거를 수집하고 분석하기는 쉽지 않다. 본 논문에서는 앞으로 대중화되는 웹OS 모바일 기기인 크롬북에 대해 사용자 모드와 관리자 모드로 나누고, 클라우드 환경을 고려한 증거수집 절차와 분석 방법을 제안하고자 한다.

• 한국실내디자인학회논문집
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• 제22권3호
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• pp.52-60
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• 2013

The contemporary concept of publicness is reinterpreted from the point of view of contemporary publicness. Contemporary perception of public space has now branched and grown into a multitude of non-traditional sites with a variety of programs in mind. In this study, the aim is to discuss how contemporary public library has been evolved as public space and how to create User-centered interaction. In the case of developed countries, the Public Libraries have showed the expected effects because they have more systematic and efficient plan. Also, these libraries are placed with each facility, not distributed separately. It promotes the accumulation of profit on the space and Increases the efficiency. They support more effectively users' activities through the linkages between each facility and create the active interaction between users. Formation of the various interactions and synergies between space had been induced. Publicity means that the state will relate a combination of a number of specific public area. In addition, open space, public place, shall be directed to: This place as one of the users in order to have meaning, must be equipped with the facilities and space to communicate and understand the local role. Methods of the study are to analyze the concept and role of the users with the concept of modern publicity, to examine the concept of multi-complexity of public libraries for the user-oriented publicness, to learn about the characteristics of public spaces in the public libraries that appear in the advanced countries, to examine how to affect these characteristics in the public libraries, and to suggest the possibility and the various application methods on the characteristics of a public space. In the end, the public libraries for the realization of the publicity, support program complexity such as education and culture, welfare facilities, and public service facilities. In the 21st century, these complexity to improve the quality of service in public libraries. These spaces can be an alternative to be kept comfortable in a more vibrant area, and can affect the social, natural, cultural, and environmental aspects of the physical environment and the objects and relationships, as well as expand.

• 한국콘텐츠학회논문지
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• 제12권4호
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• pp.1-9
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• 2012

본 연구의 목적은 이러닝 콘텐츠를 PC 기반 및 모바일 기반의 두가지 플랫폼에서 효율적으로 제작할 수 있는 방법론을 제시하는 것이다. 현재 기존 PC 기반의 이러닝 콘텐츠 제작에 많이 사용되는 플래시 기술이 iOS 등의 일부 모바일 플랫폼에서는 플래시가 지원되지 않는 호환성 문제가 발생하고 있으며, 플래시가 지원되는 모바일 플랫폼의 경우도 PC용 콘텐츠를 그대로 이용할 경우 작은 화면과 입력 인터페이스의 차이로 학습에 불편이 뒤따르는 현상이 발생하고 있다. 이러한 상황을 고려하여 본 연구에서는 HTML5 등의 표준 기술을 기반으로 두 가지 플랫폼에서 모두 서비스 가능한 콘텐츠 개발 방법론을 제시하고 있다. 결론적으로 본 연구에서 제안하는 방법론은 학습 콘텐츠 내용과 뷰를 분리하고, 구축된 콘텐츠 데이터베이스를 기반으로 다양한 형태의 뷰를 이용한 콘텐츠 구현이 가능하도록 지원하여 콘텐츠 재사용 및 다중 플랫폼 지원 부문에서 매우 효율적인 특성을 나타내도록 한다.

• 한국정보통신학회논문지
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• 제20권12호
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• pp.2267-2273
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• 2016

본 논문에서는 OSMU (One Source Multi Use) N-스크린 멀티캐스트 서비스를 위한 무선 통신 MAC 구조로서, WiMedia Distributed-MAC 프로토콜을 적용하였다. 그러나, 채널 에러율이 가변적인 무선 통신환경을 고려하면, N-스크린 고속 데이터가 손실될 가능성이 높다고 할 수 있다. 이러한 문제에 대해, WiMedia Distributed-MAC 프로토콜을 분석하여, 멀티캐스트 릴레이 기술을 제안하였다. 제안하는 멀티캐스트 릴레이 기술은 Multicast-free DRP Availability IE 기술과 결합되어, 멀티캐스트 통신에 대해 릴레이노드를 선정하고 에러율이 높은 채널을 회피하여 통신할 수 있다. 시뮬레이션을 통해 제안하는 멀티캐스트 릴레이 기술과 기존 WiMedia Distributed-MAC 멀티캐스트 기술을 멀티캐스트 노드 수에 따라 수율과 에너지 소모량을 비교 하였고, 다양한 BER (Bit Error Rate) 채널 환경에서 수율 성능을 비교하였다. 이를 통해, OSMU N-스크린 멀티캐스트 서비스에서 멀티캐스트 릴레이 기술이 적용되어야 함을 설명하였다.

• 전자공학회논문지
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• 제52권12호
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• pp.150-157
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• 2015

보행자 인식은 차량자율주행 및 사고방지를 위해 중요한 요소기술로서 많이 연구되고 있다. 이 기술들은 크게 카메라기반과 LIDAR 기반, 두 가지로 구별할 수 있다. 카메라 기반 방법과 대비되어 LIDAR 기반 방법은 화각이 넓고 조도환경에 영향을 받지 않는다는 강점이 있다. 하지만 LIDAR 기반 방법은 먼 물체를 인식하기엔 센서 해상도가 낮고, 복잡한 환경에서는 분할 오류나 폐색 등의 원인으로 인식률이 낮아진다는 문제점이 있다. 본 논문에서는 3차원 LIDAR 기반 보행자 탐지 알고리즘의 낮은 인식률을 개선시키기 위해 다중객체추적 기법의 하나인 GM-PHD 필터를 이용한 두 가지 성능 향상 방법을 제안한다. 첫 번째 방법은 GM-PHD 필터를 이용해 이전 프레임의 포인트를 현재 프레임의 물체에 자동으로 누적하여 물체 해상도 및 보행자 분류 성능을 향상시킨다. 두 번째 방법은 인식 성능이 낮은 상황에 맞춰 개선된 GM-PHD 필터를 분류된 다중객체에 적용하여 탐지 성능을 더욱 강화시킨다. 직접 취득한 도로 주행 데이터에 두 방법을 적용하여 제안한 방법이 기존의 보행자 탐지 알고리즘 성능을 대폭 향상시키는 것을 정량적으로 증명하였다.