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소석회-광물찌꺼기 고형화의 초기 수화에 미치는 황산염의 영향
이현철,민경원,유환근,Lee, Hyun-Cheol,Min, Kyoung-Won,Yoo, Hwan-Geun 대한자원환경지질학회 2013 자원환경지질 Vol.46 No.6
폐광산의 광물찌꺼기의 고형화처리 시 황산염이 초기 수화에 미치는 영향을 확인하기 위하여 본 연구를 수행하였다. 광물찌꺼기에 소석회를 결합재로 사용하였고, $Na_2SO_4$를 혼합수로 이용하여 9가지 조건의 고화체를 제작하였다. 제작된 고화체를 7일, 14일, 28일 양생 후 압축강도 측정, 중금속 용출시험, XRD 분석을 실시하였다. 증류수를 이용하여 양생을 실시한 고화체는 양생기간이 경과함에 따라 압축강도가 증가하였으며, $Na_2SO_4$를 혼합한 고화체는 양생기간 경과에 따라 압축강도가 감소하였다. $Na_2SO_4$의 농도가 증가할수록 고화체 외부 균열이 확실하게 나타났고, 시간이 경과함에 따라 균열이 내부까지 진행되었다. 고화체의 Cu, Cd, Zn, As 농도는 양생기간 경과에 따라 감소하였고, Pb의 경우 소석회 함량이 10 wt% 이상 혼합될 경우 농도가 증가함을 확인하였다. 균열이 발생된 고화체의 수화 생성물에서 석고와 $MgSO_4$ 피크가 XRD 분석으로 확인되었고, SEM-EDS를 통해 주상의 결정이 Ca, S, O로 구성된 석고임을 확인하였다. 소석회를 이용하여 광물찌꺼기를 고형화시킬 경우 황산염 생성으로 균열이 심하게 발생되므로, 황 함량이 높은 광물찌꺼기의 처리 시에는 이를 보완할 수 있는 대책이 강구되어야 할 것으로 판단된다. Influence of sulfate on the early hydration in the solidification treatment of abandoned mine tailings was characterized. Solidified specimens using hydrated lime as a binder were prepared with various amounts of added $Na_2SO_4$ and different curing days. Unconfined compressive strength measurement, heavy metal leaching test, XRD analysis were performed after 7-, 14- and 28-days curing. According to curing days strength of solidified specimens using only distilled water increased but those with addition of $Na_2SO_4$ decreased. External cracks of specimens developed definitely with increasing $Na_2SO_4$ concentration and curing days. Concentrations of Cu, Cd, Zn, and As in the leached solutions from solidified specimens decreased significantly but Pb was leached readily in cases of hydrated lime dosage more than 10 wt%. Gypsum and $MgSO_4$ were identified in the cracked solidified specimens by XRD analysis, and pillar-shaped crystals of SEM image were identified as gypsum in reference with EDS analysis. Crystallization of sulfate in the process of lime-tailing solidification caused cracking, which should be supplemented for solidification treatment of highly sulfur-contained tailing.
이현철(Hyun Cheol Lee),조원철(Won Chul Cho),전기준(Gi Joon Jeon) 대한전자공학회 1992 대한전자공학회 학술대회 Vol.1992 No.10
We propose a new control architecture which consists of a PI controller and a neural network(NN) controller connected together in parallel. This architecture is well adapted to a wide range of uncertainties and variations of systems. The NN controller is learned through weights of the emulator which identify the dynamic characteristics of the systems. A performance evaluation level of two NN's decides automatically which controller of the two controllers will be used mainly. The PI controller operates mainly during learning phase of the NN controller whereas a good performance is obtained from the NN controller only, when the NN controller is learned sufficiently.
이현철(Hyun Cheol Lee),황계영(Kae Yong Hwang) 대한피부과학회 1994 대한피부과학회지 Vol.32 No.1
We are reporting a case of multiple dermatofibromas which occuired during the treatment of systemic lupus erythematous with prednisolone for 3 years in a 30-yenr-old woman, All of the 26 lesions were 0.5-2cm sized. and had the same appearanes ad usual dermatofibromas coccurring singly. Histopathologic examination showed typical findings of dermatofibroma which were characterized hy proliferation of fibroblasts intermingled with collagen in irregular arrangement and proliferation of small vessels and endothelial cells. (Kor J Dermatol 1994; 32(1): 193-197)
우수한 기계적 특성과 형상치수 확보를 위한 정밀 압출기술개발
이현철(Lee Hyun-Cheol),이광식(Lee Kwang-Sik),오개희(Oh Kae-Hee),박상우(Park Sang-woo) 한국철도학회 2009 한국철도학회 세미나자료 Vol.2009 No.5
Most advanced countries are researching to apply light weight materials for rolling stock because weight reduction for railway body derives cost-saving, energy-saving, and high-speed. Likewise, current Korea rolling stock field makes arduous efforts of weight-reduction, miniaturization, and high-efficiency to achieve a high-speed railway. Aluminum becomes suitable material for these projects because it is much lighter than steel or stainless. Manufacturing the railway car body by using the Aluminum is increasing because Aluminum is not bringing the corrosion by unique oxidation-passivate. Aluminum extrusion profile for railway body requires a high mechanical property, awn-ate shape dimension, and stable quality because the railway body is composed with many different kinds of extruded profiles. Therefore, it is necessary to research about Aluminum precision-extrusion technology to maintain exit temperature and die load. The goal of this project is applying the Aluminum extrusion profile to next-generation railway car body by developing the Aluminum extrusion profile according to precision-extrusion technology which may maintain isothermal exit temperature.
이현철 ( Hyun Cheol Lee ),이숙경 ( Suk Keyong Lee ),이흥렬 ( Heung Ryul Lee ),이원우 ( Won Woo Lee ),김덕하 ( Duck Ha Kim ) 대한피부과학회 1995 대한피부과학회지 Vol.33 No.5
Prurigo pigmentosa is a chror ic pruritic inflammatory dermatosis characterized by erythematous papules in a reticulated pattern that resolve leaving a reticulated, mottled hyperpigmentation and rapidly response to dapsone therapy. Most cases that have been reported are from Japan. We report two cases of prurigo pigmentosa in a 21 year-old female and a 23-year-old female. Histopathologic findings of erythematous papules showed exocytosis, spongiosis, liquefaction degeneration of basal cell layer and perivascular lymphohistiocytic infiltration on the upper dermis. We treated them with dapsone, 100mg daily, which resulted in a remarkable regression of the ery thematous papules and improvenien of pruritus. (Kor J Dermatol 1995;33(5): 945-949)
이현철(Lee Hyun-Cheol),송용규(Song Yong-Kyu),김은석(Kim Eun-Seok),허기택(Hur Gi-Taek) 한국콘텐츠학회 2005 한국콘텐츠학회 종합학술대회 논문집 Vol.3 No.2
최근 컴퓨터 그래픽스 분야에서는 3차원 애니메이션에 대한 연구가 활발히 이루어지고 있다. 3차원 애니메이션에서 중요한 연구 분야 중 하나가 인간을 애니메이션 하는 것이다. 음함수 곡면 모델은 3D 캐릭터나 유체 등과 같은 복잡한 곡면으로 이루어진 객체들에 대한 3D 모델링이 용이하고 적은 양의 데이터로 다양한 형태의 곡면을 표현할 수 있다. 본 논문에서는 음함수 프리미티브를 이용한 얼굴 모델 생성 방법을 제안한다. Recently, in computer graphics, researches on 3D animations have been very active. One of the important research areas in 3D animation is animation of human being. Implicit surface model is convient for modeling objects composed of complicated surface such as 3D characters and liquids. Moreover, it can represent various forms of surfaces using a relatively small amount of data. In this paper, we propose a method of facial model generation using Implicit Primitive.
이현철(Hyun-Cheol Lee),전부일(Boo-Il Jeon),문장수(Jang-Soo Moon),이석준(Seok-June Yee) 한국항공우주학회 2009 韓國航空宇宙學會誌 Vol.37 No.2
본 연구의 목적은 주로터 블레이드와 장애물 충돌 시 실제 파괴형상과 유사한 시뮬레이션을 통해 발생되는 하중을 구하고, 이것을 이용하여 허브 및 변속장치의 안전성을 검토함으로써 승무원의 안전성을 확보하는 것이다. 헬리콥터의 실제 운용 시에 주로터 복합재 블레이드 바깥쪽 10% 지점에 직경 203㎜의 강체실린더가 충돌할 경우에도 주로터 주축은 파괴가 발생하지 않아야 하고 변속장치가 탑승공간으로 침투하는 위험한 변위가 발생하지 않아야 한다. 강체와 블레이드 충돌 시 주로터의 주축과 변속장치의 영향성을 확인하기 위하여 탄소성 손상 재질을 사용하여 복합재 블레이드와 나무(강체실린더의 경우는 강체)의 해석모델을 구성하였으며, 파괴진행과정을 실제와 유사하게 구현하기 위해 여러 개의 접촉면을 생성하여 충돌해석을 수행하였고, 구형베어링 및 리드래그댐퍼에 전달되는 하중을 구하였다 또한, 블레이드 회전속도 및 피치각도의 변화가 전달하중에 미치는 영향을 검토하였다. The objective of this study is ensuring safety of cabin when the blade impacts into a obstacle by verifying safety of the rotor mast and the transmission using impact loads calculated from the simulation. The rotor mast shall not fail and the transmission shall not be displaced into occupiable space when the main rotor composite blade impact into a 8 inch rigid cylinder in diameter on the outer 10% of the blade at operational rotor speed. To calculate the reaction loads at the spherical bearing and lead-lag damper, blade impact analysis was performed with FE model consist of composite blade, tree(or rigid cylinder) using elastic-plastic with damage material and several contact surfaces which were created to describe a progress of actual failure. Also, the reaction loads were investigated in change of blade rotation speed and pitch angle.