• Polymer(Korea)
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• v.29 no.2
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• pp.140-145
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• 2005

Effects of the polyol type and the hard segment content of thermoplastic polyurethane (TPU) on the crystallization of hard segments in TPUs were studied employing differential scanning calorimetry. Diols used for the preparation of TPUs were poly(tetramethylene ether glycol) (PTMEG), poly(propylene glycol) (PPG), polycaprolactone (PCL), poly(butylene adipate) (PBA) the molecular weights of which were 2000 and the hard segments contents of TPUs were $35\~44\;wt\%$. We found that crystallization of hard segments in TPUs were observed at higher temperatures and became faster with increasing hard segment contents of TPUs. The crystallization rate of TPU was also affected by the types of polyols used for the preparation of TPUs. It is postulated that lower miscibility of soft segments and hard segments results in higher crystallization rate and increase of cooling crystallization temperatures due to better hydrogen bending between hard segments in melts.

• Korea Petroleum Association Journal
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• no.6 s.112
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• pp.98-102
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• 1990

• Korea Petroleum Association Journal
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• no.9 s.19
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• pp.22-29
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• 1982

• Korea Petroleum Association Journal
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• no.11 s.81
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• pp.29-40
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• 1987

• Animal Systematics, Evolution and Diversity
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• v.20 no.1
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• pp.79-85
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• 2004

Pholcus gosuensis sp. novo is described from the entrance zone of Gosu cave, Chungchengbuk-do, Korea. The species is characterized by male palpal organs with three expanded apophyses and developed callosity on procursus, two frontal apophyses of chelicerae and degrading appendix, and sclerotized arches on uterus externus. The species is related to P. crassus Paik 1978 and P. acutulus Paik, 1978 in having identical uncus and embolus but differentiated from those species by the combined characters of large apophyses and heavily sclerotized callosity on procursus, and structure of arches on uterus externus.

• Clean Technology
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• v.22 no.4
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• pp.292-298
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• 2016

In this study, the pyrolysis process was carried out in order to upgrade of heavy oil contained in the resources from Indonesia. In order to investigate the composition and basic properties of the heavy oil contained in the resources, the various analytical methods was used and then the TGA (thermogravimetric) method was especially used for the thermal degradation characteristics of heavy oil in the pyrolysis. From the results obtained from the various analytical methods, the reaction conditions such as the reaction temperature was collected for the pyrolysis process and the pyrolysis using the resources containing the heavy oil was conducted using the fixed-bed reactor under the various reaction conditions. Consequently, We found that the content of heavy oil contained in the resources was about 35% and the conversion of heavy oil and the recovery efficiency of thermal degradation oil were about 21 and 80%, respectively.

• Korea Petroleum Association Journal
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• no.4 s.14
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• pp.56-57
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• 1982

세계적인 원유의 중질화 추세와 소비의 경질화 추세라는 이율배반적인 현상하에서 중질유 분해기술에 대한 연구가 활발히 진행되고 있다. 아래에 소개하는 것은 일본 통산성 "공업기술원"이 연구하고 있는 중질유을 원료로 하는 올레핀 제조법과 "중질유 대책기술연구조합"의 「중질유분해기술 」이다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.05a
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• pp.28-28
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• 2015

현재 인쇄전자 소자 생산을 위해 사용되고 있는 대부분의 그라비아 롤러는 미세 패턴의 보호와 인쇄 중 마찰에 대한 내구성을 향상시키기 위해 경질 크롬 도금 막이 사용되고 있다. 그러나 경질 크롬 도금 막의 경우 구현할 수 있는 경도(~1000 HV)와 이형성, 내마찰(마찰계수: ~ 0.6) 특성 등에 한계가 있다. 이러한 경질 크롬 도금이 적용된 그라비아 롤은 그 수명과 내구성, 구현할 수 있는 인쇄 품질 및 신뢰성 그리고 인쇄처리 속도 등에 있어 여러 문제가 있다. DLC(Diamond Like amorphous Carbon)는 낮은 마찰계수 값인 0.2 이하와 뛰어난 내마모성, 상대재료에 대한 이형성 등을 겸비한 표면강화 기술로 경질 크롬 도금막 대비 우수한 표면 경도(>1,800 HV) 특성을 갖으며, 합성된 DLC 코팅 막의 경우 정밀 인쇄 제판이 요구하는 표면거칠기를 구현할 가능성이 높다는 장점이 있다. 특히 실리콘이 첨가 된 Si-DLC의 경우 표면의 마찰계수를 0.1 이하까지 낮출 수 있는데 닥터블레이드 및 잉크, 인쇄 기재와의 마찰 훼손을 최소화시켜 그라비아 인쇄 롤의 수명을 향상시킬 수 있다. 또한 PECVD 공정을 이용하여 합성한 Si-DLC는 표면거칠기를 10nm 이하의 경면으로 구현할 수 있으며, 높은 접촉각에 의한 우수한 이형성을 통해 미세 패턴 내부에 전자잉크/페이스트가 잔류되는 현상을 억제할 수 있다. 이는 기존 경질 크롬 도금이 적용된 그라비아 롤에서 발생하는 패턴 내 잉크 잔류-고형화와 그에 의한 사용수명 단축현상을 현저히 개선시킬 수 있다.

• 한국전기화학회:학술대회논문집
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• 2001.10a
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• pp.25-25
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• 2001

• Magazine of the Korea Concrete Institute
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• v.6 no.5
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• pp.123-130
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• 1994

In this paper, a development of composite bridge decks was proposed for design of civil and architectural structures to reuse the empty cans and plastics etc. The experimental specimens were made of rigid foamed urethane taking advantage of corrosionlessness in steel bridge decks, and simplicity in the field construction. 'Therefore, introducing the empty cans into the rigid foamed urethane, this experimentation have been carried out to demonstrate and evaluate the structural behavior by means of loading and vibration tests in composite bridge decks. Consequently, it was possible that had a good effect on the structural behavior by absorbing the strain due to the low elasticity of rigid foamed urethane, and not influence to cans in composite bridges.