생형 (벤토나이트) 시스템사

여인동 ( I . D . Yeo ) 한국주조공학회 1997 한국주조공학회지 Vol.17 No.3

Introduction to “Basic Science Research Capacity Enhancement Project”

Indong Yeo(여인동),SungIll Kwon,JungHan Park 한국고분자학회 2022 한국고분자학회 학술대회 연구논문 초록집 Vol.47 No.1

용탕단조법으로 제조된 Al2O3 / AC4C 복합재료의 피로균열 전파거동에 관한 연구

여인동,이지환 ( In Dong Yeo,Chi Hwan Lee ) 한국주조공학회 1995 한국주조공학회지 Vol.15 No.4

N/A This study has been conducted with the purpose of examining the fatigue crack growth characteristics of Al₂O₃short fiber reinforced aluminum matrix composites made by squeeze casting process with different applied pressure and binder amount. Fatigue crack growth experiments have been performed under constant load amplitude method with a fixed load ratio. The rate of crack propagation was decreased with binder amount as well as applied pressure. Also fatigue crack growth path in matrix was changed from flat to rough mode with an increase of applied pressure. In the composites, fatigue crack was propagated to interface between matrix and reinforcement at 10㎫, but it was propagated to reinforcement at 20㎫. The major reason of thee result was considered that interfacial bonding force and microstructure of matrix were improved due to an increase of applied pressure. Localized ductile striation in the composites was observed at low growth rate region and such a phenominon was remarkable with an increase of applied pressure. At high growth rate region, the propensity of fracture appearance was changed from interfacial debonding to reinforcement fracture with an increase of applied pressure.

용탕단조법에 의한 Alumina 단섬유강화 AC4C 기 복합재료의 인장강도에 미치는 점결제 및 가압력의 영향

여인동,이지환 ( In Dong Yeo,Chi Hwan Lee ) 한국주조공학회 1995 한국주조공학회지 Vol.15 No.2

N/A The mechanical properties of Al/Al₂O₃composites have been investigated in relation with manufacturing factors such as applied pressure of casting and binder amount of preform. It was found that tensile strength increases with an increase of applied pressure, but decreases with binder amount. Increase of tensile strength is attributable to refinement of microstructure, improvement of intefacial bonding between Al₂O₃short fiber and matrix, decrease of porosity in the matrix. Due to the high thermal stability of alumina short fiber, tensile strength of composites at 150℃ was superior to matrix alloy at room temperature. To evaluate the strength of composites, modified Kelly-Tyson`s equation was introduced. Manufacturing factor M was obtained calculating from experimental data. M values were increased with applied pressure, but decreased with binder amount. The initiation of microcrack appeared to be at interface and reinforcement colony. Amount of micro-dimple was increased with applied pressure, and interfacial debonding phenomenon was remarkable with an increase of binder amount.

석고주조한 (石膏鑄造) Al-8.6% Si-3.6% Cu 합금의 기계적 성질에 관한 연구

여인동,김동옥,강인찬 ( In Dong Yeo,Dong Ok Kim,In Chan Kang ) 한국주조공학회 1984 한국주조공학회지 Vol.4 No.4

This paper is presented for showing the effect of cooling rate on dendrite arm spacing, correlated with the chilling power of molding materials (conventional plaster, foamed plaster, silica sand) and section thickness, and also showing relationship between dendrite arm spacing and mechanical properties for an aluminum - 8.6 percent silicon - 3.6 percent copper alloy. Local solidification time (t_f) and secondary dendrite arm spacing (d) could be varied widely in accordance with the molding materials and casting thickness, and the following relationship is obtained: d=9.4t_f^(0.31) A good correlation between dendrite arm spacing and mechanical properties such as ultimate tensile strength, yield strength, hardness was found, that is, mechanical properties decreased in a linear manner with increase in log of secondary dendrite arm spacing. Ultimate tensile strength in conventional plaster mold casting decreased by 15 percent comparing with the sand casting, where as in foamed plaster mold casting, it decreased by 30 percent comparing with the sand casting. From those results, it has been verified that DAS might be the most representative parameter for predicting mechanical properties varing with the different cooling condition.

용탕단조법에 의한 δ-Alumina 단섬유강화 AC4C 기 복합재료의 계면반응에 관한 연구

여인동,이지환 ( In Dong Yeo,Chi Hwan Lee ) 한국주조공학회 1994 한국주조공학회지 Vol.14 No.4

N/A This paper has been examined for the interfacial reactions in δ-Al₂O₃short fiber-reinforced AC4C matrix composite materials after squeeze casting and thermal exposure. After squeeze casting, it was found that reaction products exist on the Al₂O₃short fiber surface in both composites with and without silica binder. After thermal exposure at 450℃ for 30min, the thickness of reaction zone was significantly increased; Al₂O₃short fiber morphology was observed to be rough due to interfacial reaction compared with squeeze cast specimen. STEM and XRD observation and analysis showed that reaction product appears to be MgAl₂O₄.

주조용 Matchplate Pattern 제조기술

김동옥,여인동,Kim, Dong-Ok,Yeo, In-Dong 한국기계연구원 1985 기계연구원소보 Vol.14 No.-

주형매몰재에서 내화물의 변화에 따른 경화 팽창성과 열팽창성에 관한 연구

양상욱(Sang Wook Yang),여인동(In Dong Yeo),임대순(Dae Soon Lim) 한국주조공학회 1999 한국주조공학회지 Vol.19 No.2

N/A As the developed investments material, Gypsum-bonded Investments have been used for Dental Castings, especially Gold-Alloys. Investments for Casting have Calcium sulfate hemihydrate as binders and Quartz or Cristobalite as Refractory Fillers. In this case, The rate of thermal expansion must be higher thermal expansion as compensating for Gold-alloy`s contraction during solidification. In this study, We have made the effects on Setting and Thermal expansion of investments including cristobalite, mullite and chamotte as a refractory. Setting expansion was changed with the content of water and absorption property of surface on refractory fillers. Thermal expansion was presented to drop of expansion by diffenrence of the rate of thermal expansion on Refractory fillers. (Received December 19, 1998)

생체재료용 Ti-Nb-Si합금의 미세조직과 기계적 성질

김한솔 ( Han Sol Kim ),여인동 ( In Dong Yeo ),김원용 ( Won Yong Kim ),조대형 ( Dae Hyung Cho ),임성환 ( Sung Hwan Lim ),문민석 ( Min Seok Moon ),강황진 ( Whang Jin Kang ) 대한금속재료학회 ( 구 대한금속학회 ) 2006 대한금속·재료학회지 Vol.44 No.6

We report on advanced β-titanium alloys having excellent biocompatibility without containing V or Al that has been known as a toxic element for human body, and on a low elastic modulus to be used in the fields of artificial joint and dental implant in the replacement of natural human bone. Ternary Ti-Nb-Si alloys consisting of biocompatible alloying elements have been produced to investigate the alloying effect on microstructure, elastic modulus and mechanical properties. On the basis of experimental results obtained, it is suggested that Si has an effective role to suppress the formation of ω-phase leading to reduction in elastic modulus.

Sol-gel법으로 이산화티탄(TiO₂)을 저온소성 도포시킨 경량골재콘크리트의 아세트알데히드(CH₃CHO) 제거 특성

이승한(Lee Sung Han),여인동(Yeo In Dong),정용욱(Jung Yong Wook),장석수(Jang Suk Soo) 대한토목학회 2011 대한토목학회논문집 A Vol.31 No.2A

최근 대기오염 물질을 제거하기 위하여 TiO₂ 등의 광촉매 재료를 사용한 기능성콘크리트에 대한 연구가 활발히 이루어지고 있다. 이들 연구에서 TiO₂의 흡착은 콘크리트에 직접 혼합하거나, 현탁액을 표면에 직접 도포하는 방법을 사용하고 있다. 이 중 콘크리트에 TiO₂를 직접 혼합하는 방법은 TiO₂의 사용량에 비하여 효능이 떨어져 표면에 직접 도포하는 방법이 많이 이용된다. TiO₂의 표면도포는 광촉매의 활성화와 접착성 증대를 위하여 400℃이상의 고온 열처리를 실시하게 되며, 이는 콘크리트 수회생성물의 탈수 · 수축으로 내부균열을 발생시키는 원인이 되기도 한다. 이에 이 연구에서는 TiO₂의 저온도포가 가능한 Sol-gel법으로 TiO₂를 제조하였으며 펄라이트 사용 경량골재콘크리트에 저온 고정화하여 TiO₂도포 성능을 평가하였다. 또한 펄라이트 입경을 2.5~5.0 ㎜와 5.0 ㎜이상으로 구분하여 펄라이트 입경, TiO₂ 혼입방법과 혼입률 및 시간경과에 따른 CH₃CHO 제거 특성을 검토하였다. 실험결과, Sol-gel법으로 제조한 TiO₂를 120℃에서 저온 도포할 때 XRF 정량분석에서 TiO₂38%, SiO₂ 29%, CaO 18% 순으로 나타나 TiO₂ 도포율은 높게 나타났다. 또한 펄라이트 입경 2.5~5.0 ㎜에서 TiO₂를 저온도포한 경량골재콘크리트의 CH₃CHO 제거 특성은 Sol-gel법으로 제조된 TiO₂를 7% 표면 도포하였을 경우 94%로 나타나 10%를 혼입할 때 72%에 비해 약 20%정도 높게 나타났다. 또한 펄라이트 입경 5.0 ㎜이상에서 TiO₂를 10%로 치환하여 혼합하였을 경우 CH₃CHO 제거율은 69%로 펄라이트 입경 2.5~5.0 ㎜에 대한 72%와 비슷하게 나타나 펄라이트 입경이 CH₃CHO 제거율에 미치는 영향은 크지 않았다. 시간 경과에 따른 CH₃CHO 제거 특성은 전 시험편의 10시간 평균 제거율이 20시간 전체 제거율의 84% 수준으로 나타나 반응 초기에 제거율이 높은 것으로 나타났다. Recently studies on functional concrete with a photocatalytic material such as TiO₂ have actively been carried out in order to remove air pollutants. The absorbtion of TiO₂ from those studies is applied by it being directly mixed into concrete or by suspension coated on the surface. When it comes to the effectiveness, the former process is less than that of the latter compared with the TiO₂ lise. As a result, the direct coating of TiO₂ on materials' surface is more used for effectiveness. The Surface spread of it needs to have a more than 400℃ heat treat done to stimulate the activation and adhesion of photocatalysis. Heat treat consequently leads hydration products in concrete to be dehydrated and shrunk and is the cause of cracking. The study produces TiO₂ used Sol-gel method which enables it to be coated with a low temperature treat, applies it to pearlite using Lightweight Aggregate Concrete fixed with a low temperature treat and evaluates the spread performance of it. In addition to this, the size of pearlite is divided into two types: One is 2.5 ㎜ to 5.0 ㎜ and the other is more than 5.0 ㎜ for the benefit of finding out the removal characteristics of CH₃CHO whether they are affected by pearlite size, mixing method and ratio with TiO₂ and elapsed time. The result of this experiment shows that although TiO₂ produced by Sol-gel method is treated with 120 temperature, it maintains a high spread rate on the XRF(X ray Florescence) quantitative analysis which ranks TiO₂ 38 percent, SiO₂ 29 percent and CaO 18 percent. In the size of perlite from 2.5 ㎜ to 5.0 ㎜, the removal characteristic of CH₃CHO from a low temperature heated Lightweight concrete appears 20 percent higher when TiO₂ with Sol-gel method is spreaded on the 7 percent of surface. In other words, the removal rate is 94 percent compared with the 72 percent where TiO₂ is mixed in 10 percent surface. In more than 5.0 mm sized perlite, the removal rate of CH₃CHO, when TiO₂ is mixed with 10 percent, is 69 percent, which is similar with that of the previous case. It suggests that the size of pearlite has little effects on the removal rate of CH₃CHO. In terms of Elapsed time, the removal characteristic seems apparent at the early stage, where the average removal rate for the first 10 hours takes up 84 percent compared with that of 20 hours.