• Elastomers and Composites
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• 제48권3호
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• pp.232-240
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• 2013

자기치유형 아스팔트를 구현하기 위하여 치유제로 디메틸페놀을 사용하여 내부층을 이루고 바깥층이 멜라민 수지로 이루어진 마이크로켑슐을 제조하였다. 마이크로캡슐이 내재된 아스팔트는 일반 아스팔트에 비해 높은 기계적 성질을 나타내었다. 그대로 길어질수록 마이크로캡슐이 함유된 아스팔트는 함유되지 않은 아스팔트보다 더 높은 충격 강도를 나타내었으며 15일의 휴식기간에 최초의 물성을 회복하였다. 이는 X-선 사진에서 보듯이, 깨어진 아스팔트 경계면에 있던 마이크로캡슐이 아스팔트와 동시에 깨지면서 캡슐 안에 있던 단량체인 디메틸페놀이 흘러나와 외부의 반응촉매 투입 없이 아스팔트 자체의 금속촉매와 아민촉매 및 공기 중의 산소분자에 의하여 열가소성 고강성 플라스틱 고분자인 폴리페닐렌옥사이드가 자율적으로 중합되면서 깨어진 아스팔트의 경계면을 메우면서 최초의 물성으로 복구된 것이다. 이는 마이크로캡슐을 함유한 아스팔트는 자가복구능을 갖고 있음을 의미한다.

• Journal of Astronomy and Space Sciences
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• 제34권4호
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• pp.289-302
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• 2017

The key risk analysis technologies for the re-entry of space objects into Earth's atmosphere are divided into four categories: cataloguing and databases of the re-entry of space objects, lifetime and re-entry trajectory predictions, break-up models after re-entry and multiple debris distribution predictions, and ground impact probability models. In this study, we focused on reentry prediction, including orbital lifetime assessments, for space situational awareness systems. Re-entry predictions are very difficult and are affected by various sources of uncertainty. In particular, during uncontrolled re-entry, large spacecraft may break into several pieces of debris, and the surviving fragments can be a significant hazard for persons and properties on the ground. In recent years, specific methods and procedures have been developed to provide clear information for predicting and analyzing the re-entry of space objects and for ground-risk assessments. Representative tools include object reentry survival analysis tool (ORSAT) and debris assessment software (DAS) developed by National Aeronautics and Space Administration (NASA), spacecraft atmospheric re-entry and aerothermal break-up (SCARAB) and debris risk assessment and mitigation analysis (DRAMA) developed by European Space Agency (ESA), and semi-analytic tool for end of life analysis (STELA) developed by Centre National d'Etudes Spatiales (CNES). In this study, various surveys of existing re-entry space objects are reviewed, and an efficient re-entry prediction technique is suggested based on STELA, the life-cycle analysis tool for satellites, and DRAMA, a re-entry analysis tool. To verify the proposed method, the re-entry of the Tiangong-1 Space Lab, which is expected to re-enter Earth's atmosphere shortly, was simulated. Eventually, these results will provide a basis for space situational awareness risk analyses of the re-entry of space objects.

• Journal of Welding and Joining
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• 제35권3호
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• pp.82-87
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• 2017

Recent trends in shipbuilding and offshore industries are a huge increase in the ship size and the exploration and production of oil and natural gas in the arctic offshore region. High performance steel plates are required by these industrial trends. Also in IMO(International Maritime Organization) has begun to regulate of fuel of ship to environmental protection, therefore it is little bit difficult to use bunker-C oil to working ship. As the problem of environmental change such as global warming is emerged, the operation of the ship is considered to be involved in the environmental change problem, and the regulation of environmental pollution is gradually strengthened. As these environmental regulations are strengthened demand for LNG fuel ships is rapidly increasing. Currently, cryogenic steels used in LNG tanks include aluminum alloy, SUS 304, and 9%-Ni steel. Those steels are has high cost to construction of large LNG carrier. The new materials were suggested several steel mills to decrease construction cost and easy construction. The new cryogenic steel should be evaluate safety to applied real structure include LNG ship. Therefore, in this study, fracture toughness of weld joints were investigated with cryogenic steel for application of LNG tank.

• 한국실내디자인학회논문집
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• 제17권2호
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• pp.13-21
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• 2008

The purpose of this study is to analyze the development and characteristics of movable-housing planning concept. A document research method was used to analyze and classified the development of the movable-housing concept of 20th century. Through this study, the following conclusions have been reached; First, the origin of the movable-housing is from the prehistoric and traditional portable buildings, also due to the emergence of nomadic lifestyle using car traveling and mobile home in the 1920's. Second, the development of the movable-housing in 20th century was classified as follows; (1) In order to obtain the productivity and efficiency drawing from the industrialized-housing in the early of 1900s, movable furniture and flexibility was proposed. (2) American mobile home in 1920's, influenced by the development of car industry, was the most successful example of a factory-built building to be found in the world. (3) Dymaxion house and dome by R.B.Fuller, an aggregation of high-tech mechanical equipment, had a great impact on the development the concept of 'mobility' and influenced Archigram & Metabolist's movable capsule ideas in 1960's. (4) The lightweight materials such as plastic, duralumin and pneumatic structure were adopted for movable-housing in 1960's. Through this research, It is discovered that the stage of social development has close links with the developing aspects of movable-housing concepts. This study shows that the combination of three planning concepts such as flexible housing, mobile-housing and capsule will be more ideal in movable-housing planning rather than relying on just one type.

• 자원리싸이클링
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• 제17권3호
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• pp.10-20
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• 2008

농업용 폐비닐의 재활용에 대한 무기충진재의 거동을 연구하기 위하여 한국환경자원공사 시화 및 정읍공장에서 세척된 PE fluff들을 각각 사용하였다. 먼저 PE 플러프에 무기충진재인 탄산칼슘과 칼펫을 배합비율별로 혼합하여 용융 압출을 통한 시험용 펠렛들을 제조한 후 프레스 몰딩을 거쳐 시료별로 시험용 시트들을 제작하였다. 이들 무기충진 복합재의 기계적 특성인 인장, 굴곡, Izod 충격시험을 실시하였고, 열적 특성인 열변형온도, vicat 연화온도, 용융흐름지수(MFI)를 시험 및 분석을 하였다. 또한 플라스틱 내부에서 무기충진재의 분산성 및 wetting정도를 확인하기 위하여 SEM을 통해 모폴로지를 조사하였다. 이들 결과로부터 물리적인 측면과 경제적인 관점에서 재생 PE와 무기충진재의 최적 배합비들을 얻었다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2014년도 추계 학술논문 발표대회
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• pp.78-80
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• 2014

Silicone structural glazing (SSG) is a method utilizing a silicone adhesive to attach glass, metal, or other panel material to the structure of a building. Windload and other impact loads on the facade are transferred from the glass or panel through the silicone structural sealant to the systems' framework. Silicone structural glazing systems are currently a very common method of glazing throughout the world. Locally, structural silicone glazing has become very common to achieve aesthetically pleasing and high utilization of small land for both residential and commercial building. Although structural silicone glazing has been utilized for approximately thirty years in Korea, the understanding of its technology was low and limited. Consequently, Korean projects experienced many quality issues during assembly and construction, even in very recently finished buildings. Adhesion loss and water infiltration occurred on more than one project, and the time and cost to repair these issues were substantial. In general, there are two kinds of structural silicones depending on fabrication methods. 1part structural silicone is for site glazing system and 2part structural silicone is for unitized factory glazing system. In this paper, 2part structural silicone which is very common for factory fabricating curtainwall systems was evaluated with regards to various mixing ratio. Since the structural performance of 2part sealant can be affected by mixing ratios, some extra ranges of recommended mixing ratio were evaluated to see any performance differences. Besides on cure profile, comparative evaluations for mechanical properties and adhesion develop on common building substrates were conducted.

• Korean Chemical Engineering Research
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• 제46권1호
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• pp.63-68
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• 2008

초임계 유체 공정을 이용하여 가교 폴리에틸렌 수지를 탈가교화하여 재활용하는 방법을 조사하였다. 가교 폴리에틸렌 수지는 메탄올을 이용한 초임계 반응 시 탈가교화가 이루어져 재활용 될 수 있다. 초임계를 이용한 탈가교화 반응은 반응온도에 의해 크게 영향을 받으며 $360^{\circ}C$부터 $400^{\circ}C$ 구간에서 온도의 증가에 따라 탈가교화가 급격히 촉진되었다. 반응온도의 증가에 따라 생성물인 탈가교 폴리에틸렌의 가교도, 분자량, 기계적 물성은 감소했지만, $360^{\circ}C$에서 탈가교된 폴리에틸렌은 가교전의 원료로 사용된 폴리에틸렌과 비교할만한 연신강도와 내충격강도를 보였다. 본 연구의 모든 반응조건에서 폴리에틸렌의 주쇄의 화학구조는 반응조건에 거의 영향을 받지 않았다.

• 청정기술
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• 제18권1호
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• pp.14-21
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• 2012

친환경 건축물에 사용되는 미네랄울, 폴리우레탄 등 전통적인 단열재로부터 최근에 주목받고 있는 VIP (Vacuum Insulation Panel), 에어로젤, 그리고 미래기술로 연구되고 있는 VIM (Vacuum Insulation Material), DIM (Dynamic Insulation Material) 등 단열재 및 단열 시스템의 특성과 장단점을 비교하였다. 매우 낮은 열전도율을 지닌 VIP 및 에어로젤은 기존 단열재에 비해 에너지 소모를 줄일 수 있으므로 주거면적을 크게 확대할 수 있는 장점이 있으며, 특히 에어로젤은 반투명 및 투명재질로 만들 수 있어 건물에 응용될 수 있는 가능성이 매우 크다. 단열재는 낮은 열전도율뿐만 아니라, 건설현장 응용성, 기계적강도, 내화성, 비용 및 환경영향 등을 고려하여야 하므로, 전통적인 단열재 및 최신 단열재를 활용하고 지속적으로 개선시키는 노력을 해야 할 것이다.

• Wind and Structures
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• 제13권5호
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• pp.413-431
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• 2010

The focus of this article is on the assessment of vertical wind vector components and their aerodynamic impact on lattice framework, specifically two distinct sections of a guyed transmission tower. Thunderstorm winds, notably very localized events such as convective downdrafts (including downbursts) and tornadoes, result in a different load on a tower's structural system in terms of magnitude and spatial distribution when compared to horizontal synoptic winds. Findings of previous model-scale experiments are outlined and their results considered for the development of a testing rig that allows for rotation about multiple body axes through a series of wind tunnel tests. Experimental results for the wind loads on two unique experimental models are presented and the difference in behaviour discussed. For a model cross arm with a solidity ratio of approximately 30%, the drag load was increased by 14% when at a pitch angle of $20^{\circ}$. Although the effects of rotation about the vertical body axis, or the traditional 'angle of attack', are recognized by design codes as being significant, provisions for vertical winds are absent from each set of wind loading specifications examined. The inclusion of a factor to relate winds with a vertical component to the horizontal speed is evaluated as a vertical wind factor applicable to load calculations. Member complexity and asymmetric geometry often complicate the use of lattice wind loading provisions, which is a challenge that extends to future studies and codification. Nevertheless, the present work is intended to establish a basis for such studies.

• Journal of Advanced Marine Engineering and Technology
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• 제37권5호
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• pp.510-519
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• 2013

Urea-SCR시스템에 적용하기 위한 액막형 선회분사기의 분사압력변화에 따른 분무특성이 실험적으로 조사되었다. 실험에 사용된 노즐은 형상비 3.1을 갖는 단공 압력식 액막형 선회노즐이며, 노즐선단에 분사되는 유체에 선회류를 형성하기 위한 선회기가 설치되어 있다. 노즐의 분사량 조절은 PWM(pulse width modulation)기법에 의해 제어되었다. 분무의 발달과정은 2차원 PIV에 의해 가시화되었으며, 분무각 변화가 조사되었다. 분무액적의 속도 및 크기는 2차원 PDPA에 의해 상온 대기압 조건에서 측정되었다. 분무구조는 분사압력에 큰 영향을 받으며, SMD는 분사압력 증가에 따라 감소하며 선행연구자의 반실험적 결과와 유사한 경향을 보임을 알 수 있었다.