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윤호상,진춘조,유광하,이상엽,이수인,정상만,김선두,이순제,이길도,전혜정 건국대학교 의과학연구소 2000 건국의과학학술지 Vol.10 No.-
Chronic eosinophilic pneumonia(CEP) is a rare disease of unknown etiology characterized by chronic infiltration of the lung with eosinophils. It presents with profound systemic symptoms comprising fever, night sweats, weight loss, dyspnea and blood eosinophilia with nonsegmental air-space consolidation confined to the outer third of the lung, the "photographic negative of pulmonary edema". Histopathologic features of chronic eosinophilic pneumonia are intraalveolar and interstitial infiltrations with eosinophils, histiocytes, giant cells, scattered lymphocytes and plasma cells. Glucocorticoid therapy cause prompt resolution of symptoms as well as disappearans of blood eosinophils, elevated serum Ig E levels and the roentgenographic lesions. Infrequent radiographic findings include nodular infiltrates, consolidations, cavitations, atelectasis and pleural effusions. Deaths from CEP although rare, have been reported, but the majorities of CEP have benign courses and do not need a therapy with ventilator. We report a case of chronic eosinophilic pneumonia, which had a sudden course associated with diffuse pneumonic consolidations on the both lung and bilateral pleural effusion.
Nano/micro particle beam for ceramic deposition and mechanical etching
Chun, Doo-Man,Kim, Min-Saeng,Yeo, Jun-Cheol,Kim, Min-Hyeng,Lee, Caroline Sunyong,Ahn, Sung-Hoon Royal Swedish Academy of Sciences 2010 Physica scripta Vol.2010 No.t139
<P>Nano/micro particle beam (NPB) is a newly developed ceramic deposition and mechanical etching process. Additive (deposition) and subtractive (mechanical etching) processes can be realized in one manufacturing process using ceramic nano/micro particles. Nano- or micro-sized powders are sprayed through the supersonic nozzle at room temperature and low vacuum conditions. According to the process conditions, the ceramic powder can be deposited on metal substrates without thermal damage, and mechanical etching can be conducted in the same process with a simple change of process conditions and powders. In the present work, ceramic aluminum oxide (Al<SUB>2</SUB>O<SUB>3</SUB>) thin films were deposited on metal substrates. In addition, the glass substrate was etched using a mask to make small channels. Deposited and mechanically etched surface morphology, coating thickness and channel depth were investigated. The test results showed that the NPB provides a feasible additive and subtractive process using ceramic powders.</P>
Doo-Man Chun,Min-Hyeng Kim,Jae-Chul Lee,Sung-Hoon Ahn 한국정밀공학회 2008 International Journal of Precision Engineering and Vol.9 No.1
A new nano-particle deposition system (NPDS) was developed for a ceramic and metal coating process. Nano-and micro-sized powders were sprayed through a supersonic nozzle at room temperature and low vacuum conditions to create ceramic and metal thin films on metal and polymer substrates without thermal damage. Ceramic titanium dioxide (TiO₂) powder was deposited on polyethylene terephthalate substrates and metal tin (Sn) powder was deposited on SUS substrates. Deposition images were obtained and the resulting chemical composition was measured using X-ray photoelectron spectroscopy. The test results demonstrated that the new NPDS provides a noble coating method for ceramic and metal materials.
Chun, Doo Man,Kim, Hyung Jung,Lee, Jae Chul,Ahn, Sung Hoon Trans Tech Publications, Ltd. 2007 Key Engineering Materials Vol.345-346 No.-
<P>Material selection became one of the important activities for engineers in design and manufacturing processes. A selected material at the beginning of design stage affects functionality of the designed part as well as manufacturability and cost of the final product. Unfortunately there are not many accessible material databases that can be properly used for design. In this research, a web-based material database was constructed. In order to assist designers to compare different materials, two-dimensional and three-dimensional graphs for comparison of material properties were provided via the web browser. Using these graphical tools, multi-dimensional comparison was available in more intuitive manner. In addition, this web site is open to the public, and one may add new material properties to the database in order to compare the data with existing materials. To provide the database in a commercial CAD (Computer Aided Design) environment, API (Application Programming Interface) modules were developed using Web services. The web-based material database can be accessible from http://fab.snu.ac.kr/matdb.</P>
Chun, Doo-Man,Ngo, Chi-Vinh,Lee, Kyong-Min Elsevier 2016 CIRP annals ... manufacturing technology Vol.65 No.1
<P><B>Abstract</B></P> <P>Recently, cost-effective nanosecond laser texturing has been used for the fabrication of superhydrophobic surface on metals such as copper and brass. However, the wettability change from hydrophilicity to superhydrophobicity took a relatively long time from several days to several months since the textured surface was exposed to ambient conditions. To reduce the time required for wettability changes for industrial applications, a facile post process was introduced. This paper demonstrates fast wettability change of a nanosecond laser textured copper surface from hydrophilic to superhydrophobic using additional low-temperature annealing (100°C). Surface characteristics were evaluated to explain the underlying mechanism.</P>
Chun, Doo-Man,Kim, Min-Hyeng,Lee, Jae-Chul,Ahn, Sung-Hoon Korean Society for Precision Engineering 2008 International Journal of Precision Engineering and Vol.9 No.1
A new nano-particle deposition system (NPDS) was developed for a ceramic and metal coating process. Nano- and micro-sized powders were sprayed through a supersonic nozzle at room temperature and low vacuum conditions to create ceramic and metal thin films on metal and polymer substrates without thermal damage. Ceramic titanium dioxide ($TiO_2$) powder was deposited on polyethylene terephthalate substrates and metal tin (Sn) powder was deposited on SUS substrates. Deposition images were obtained and the resulting chemical composition was measured using X-ray photoelectron spectroscopy. The test results demonstrated that the new NPDS provides a noble coating method for ceramic and metal materials.
차량 경량화를 위한 사출성형 유리섬유강화플라스틱의 온도 및 수분 흡수에 따른 기계적 물성 변화
천두만(Doo-Man Chun),안성훈(Sung-Hoon Ahn) 대한기계학회 2013 大韓機械學會論文集A Vol.37 No.2
최근 차량 경량화를 통한 에너지 절감을 위해서 무거운 철강재료를 경금속이나 복합재료로 대체하는 연구가 많이 진행되고 있다. 이중, 폴리머 기반의 복합재료는 사출성형을 통해서 복잡한 형상의 제작이 가능하고, 유리섬유나 탄소섬유를 함께 사용하여 철강재료 수준으로 기계적 물성을 높일 수 있는 장점이 있다. 하지만 엔진의 고온과 우기에서의 높은 습도 환경은 폴리머의 기계적 물성을 낮추기 때문에 재료선택 과정에서 반드시 고려해야 한다. 본 연구에서는 사출성형을 통해 만들어진 유리섬유강화플라스틱을 엔진룸 내부 온도와 유사한 85℃ 환경과 우기시의 최대 수분흡수 환경하에서의 기계적 물성변화를 인장시험을 통해 알아보았다. 그 결과, 고온환경에서 최대인장강도가 약 23% 감소를 보였고, 수분에 의해서는 약 30% 감소하였으며, 고온과 수분 모두에 대해서는 약 70% 감소를 확인하였으며 이는 재료 선정시 반드시 고려해야 할 영향으로 판단되었다. Owing to the global energy crisis, studies have strongly focused on realizing energy savings through vehicle weight reduction using light metal alloys or polymer composites. Polymer composites afford many advantages including enabling the fabrication of complex shapes by injection molding, and glass and carbon fibers offer improved mechanical properties. However, the high temperature in an engine room and the high humidity during the rainy season can degrade the mechanical properties of the polymer. In this study, the mechanical properties of injection-molded glass-fiberreinforced polymer were assessed at a temperature of 85°C and the maximum moisture absorption conditions. The result showed a 23% reduction in the maximum tensile strength under high temperature, 30% reduction under maximum moisture absorption, and 70% reduction under both heat and moisture conditions. For material selection during the design process, the effects of high temperature and high humidity should be considered.