해리온도와 반응성 희석제 함량에 따른 저점도 폴리우레탄 핫멜트 접착제의 접착특성

최민지 ( Min Ji Choi ),정부영 ( Boo Young Jeong ),천정미 ( Jung Mi Cheon ),하창식 ( Chang-sik Ha ),천제환 ( Jae Hwan Chun ) 한국접착및계면학회 2016 접착 및 계면 Vol.17 No.2

본 연구에서는 반응성 희석제 함량에 따라 접착강도 및 물성을 향상시키기 위해 polyether polyol/polyester polyol, 4,4-dicyclohexylmethane diisocyanate (H12MDI), 2-butanone oxime (MEKO)를 사용하여 저점도 폴리우레탄 핫멜트를 합성하였다. 합성된 저점도 폴리우레탄 핫멜트의 물성은 FT-IR, viscosity meter 및 UTM 등을 통해 확인하였다. 반응성 희석제의 함량이 증가하고 NCO-blocked prepolymer가감소함에 따라 저점도 폴리우레탄 핫멜트 접착제의 점도는 증가하였으며, OH-terminated oligomer, NCO-blocked prepolymer, 반응성 희석제 함량의 비가 1 : 0.5 : 0.5일 때 1.1 kgf/cm 접착강도를 나타내었다. In this study, low-viscosity polyurethane hot-melt were synthesized with polyether polyol / polyester polyol, 4,4-dicyclohexylmethane diisocyanate (H12MDI), 2-butanone oxime (MEKO) to improve the properties and peel strength. The properties of the synthesized low-viscosity polyurethane hot-melt was evaluated through FT-IR, viscosity meter and UTM. When the content of the reactive diluent increases and the NCO-blocked prepolymer decreases, the viscosity of low-viscosity polyurethane hot-melt adhesive was increased. When the ratio of OH-terminated oligomer, NCO-blocked prepolymer and content of reactive diluent is 1 : 0.5 : 0.5, low-viscosity polyurethane hot-melt showed 1.1 kgf/cm peel strength.

소결 분위기와 조성이 $TiB_2$-AlN-BN 복합체의 반응 가압 소결에 미치는 영향

이기민,김형종,최헌진,이준근 한국세라믹학회 2000 한국세라믹학회지 Vol.37 No.7

Effects of the chemical composition and sintering atmosphere on the formation of reaction phases and physical properties of reactive hot-pressed TiB2-AlN-BN composites were investigated. At N2 atmosphere, TiN was formed by the reaction between Ti and N2, which inhibited the densification and results in inferior mechanical-and electrical properties of the composites. However, at Ar atmosphere, enhanced densification and physical properties of composites were obtained due to that the TiN formation reaction was excluded. Densification of the composites was also hindered by BN, therefore, inferior mechanical-and electrical properties of composites were obtained with amount of BN in the starting materials. At Ar atmosphere, TiB2-AlN-BN composites having 318 MPa of flexural strength, 3.5 MPa.m1/2 of fracture toughness and 276$\mu$Ω.cm of electrical resistivity were fabricated from mole ratio 1:2:1.6 of Ti-Al-BN mixtures.

Reactive Synthesis of ZrB2-based Ultra High Temperature Ceramics

Hai-Tao Liu,Guo-Jun Zhang† 한국세라믹학회 2012 한국세라믹학회지 Vol.49 No.4

Reactive processing, such as reactive hot pressing (RHP) and reactive spark plasma sintering (R-SPS), is effective densification method to prepare ZrB2-based ultra high temperature ceramics (UHTCs). The present paper reviewed some typical reactive processing of ZrB2-based UHTCs. All the reactions from the starting materials in the reactive processing are thermodynamically favorable, which generate enough energy and driving force for the densification of the final products under a relatively low temperature. Besides, compared with non-reactive processing, anisotropic ZrB2 grains, such as ZrB2 platelets, can only be obtained in the reactive processing, resulting in an improvement of the mechanical properties.

Reactive Synthesis of ZrB₂-based Ultra High Temperature Ceramics

Liu, Hai-Tao,Zhang, Guo-Jun The Korean Ceramic Society 2012 한국세라믹학회지 Vol.49 No.4

Reactive processing, such as reactive hot pressing (RHP) and reactive spark plasma sintering (R-SPS), is effective densification method to prepare $ZrB_2$-based ultra high temperature ceramics (UHTCs). The present paper reviewed some typical reactive processing of $ZrB_2$-based UHTCs. All the reactions from the starting materials in the reactive processing are thermodynamically favorable, which generate enough energy and driving force for the densification of the final products under a relatively low temperature. Besides, compared with non-reactive processing, anisotropic $ZrB_2$ grains, such as $ZrB_2$ platelets, can only be obtained in the reactive processing, resulting in an improvement of the mechanical properties.

Cross-Reactivity and Digestive Enzyme Stability of Peach, Korean Cherry, and Hot Pepper

Eun-Jung Kim(김은정),Yu-Jin Ko(고유진),Gyeong-Ran Lee(이경란),Hui-Gyeong Seol(설희경),Chang-Min Kang(강창민),Chung-Ho Ryu(류충호) 한국생명과학회 2012 생명과학회지 Vol.22 No.11

복숭아는 오래 전부터 알레르기를 일으키는 식품으로 알려져 있으나 특정 식품과의 교차반응에 대한 연구는 부족한 실정이다. 본 연구에서는 한국에서 재배되고 있는 복숭아, 앵두, 고추의 단백질을 추출하여 복숭아 알레르기를 가진 환자가 앵두와 고추에 대해 교차반응성을 일으키는지 확인하고 이 단백질들의 소화효소처리에 따른 안정성을 조사하였다. 복숭아, 앵두 및 고추 단백질 추출물은 Tricine-SDS-PAGE상에서 3 kDa부터 26 kDa 이상까지 넓은 범위의 단백질 분포를 보였으나 각기 다른 패턴을 가지는 것을 확인하였다. 복숭아 단백질의 항원성을 확인하기 위해 복숭아 민감성 환자의 혈청과의 IgE반응성을 확인한 결과, 환자 혈청은 모두 복숭아의 주요 항원성 단백질 lipid transfer protein로 예상되는 9 kDa 부근에서 강한 IgE결합력을 보였으며 또한 9 kDa 단백질이 anti-LTP1 polyclonal antibody에 의해 검출되는 것을 확인하였다. 앵두와 고추 단백질 추출물은 23 kDa 부근에서의 IgE결합력이 9 kDa과의 반응성보다 크게 나타났다. 복숭아, 앵두 및 고추의 소화효소에 대한 안정성을 SDS-PAGE 상에서 확인한 결과, 복숭아, 앵두 및 고추의 항원성 단백질은 인공 위액 및 장액에 의해 완전히 분해되지 않아 알레르기를 유발할 잠재성이 있는 것을 확인할 수 있었다. 본 연구 결과를 바탕으로, 복숭아, 앵두 및 고추 단백질 추출물이 소화효소처리에 안정성을 가지는 특성을 가지며 복숭아 알레르기 증상을 가지는 사람에게 앵두 및 고추는 교차반응성을 일으킬 가능성이 크다는 것을 확인할 수 있었다. Peach (Prunus persica) has been recognized as a food allergen for over 20 years. However, there is little information about cross-reactivity with other foods. The aim of this study was to research cross-reactivity of Korean cherry and hot pepper on patients allergic to peach and its stability by digestive enzyme treatment. Peach, Korean cherry, and hot pepper proteins were extracted and separated by Tricine-SDS-PAGE analysis. The protein extracts had a wide range of molecular weight, from 3 kDa to more than 26 kDa, and displayed different patterns of protein bands on Tricine-SDS-PAGE. Peach allergic patients’ sera were used to detect the allergenic protein in three samples. Three peach allergic patients’ sera reacted strongly with 9 kDa protein of peach, which was the expected lipid transfer protein (LTP) as the major allergen of peach and was detected with anti-LTP1 polyclonal antibody. However, the reactivity of the 23 kDa protein in Korean cherry and hot pepper protein was stronger than that of the 9 kDa protein. The stability of protein extracts on digestive enzyme treatment was examined using simulated gastric fluids (SGF) and simulated intestinal fluids (SIF), in which digestive enzyme stability is one of the characteristics of allergen potentially causing food allergy. Findings confirmed that allergenic proteins in peach, Korean cherry, and hot pepper were not completely digested by SGF and SIF treatments from results of SDS-PAGE analysis. These results confirmed that Korean cherry and hot pepper might cause cross-reactivity in peach allergic patients, and its allergenic proteins have stability against digestive enzymes.

DEVELOPMENT OF A TWO-DIMENSIONAL THERMOHYDRAULIC HOT POOL MODEL AND ITS EFFECTS ON REACTIVITY FEEDBACK DURING A UTOP IN LIQUID METAL REACTORS

이용범,정해용,조충호,권영민,하귀석,장원표,석수동,한도희 한국원자력학회 2009 Nuclear Engineering and Technology Vol.41 No.8

The existence of a large sodium pool in the KALIMER, a pool-type LMR developed by the Korea Atomic Energy Research Institute, plays an important role in reactor safety and operability because it determines the grace time for operators to cope with an abnormal event and to terminate a transient before reactor enters into an accident condition. A two-dimensional hot pool model has been developed and implemented in the SSC-K code, and has been successfully applied for the assessment of safety issues in the conceptual design of KALIMER and for the analysis of anticipated system transients. The other important models of the SSC-K code include a three-dimensional core thermal-hydraulic model, a reactivity model, a passive decay heat removal system model, and an intermediate heat transport system and steam generation system model. The capability of the developed two-dimensional hot pool model was evaluated with a comparison of the temperature distribution calculated with the CFX code. The predicted hot pool coolant temperature distributions obtained with the two-dimensional hot pool model agreed well with those predicted with the CFX code. Variations in the temperature distribution of the hot pool affect the reactivity feedback due to an expansion of the control rod drive line (CRDL) immersed in the pool. The existing CRDL reactivity model of the SSC-K code has been modified based on the detailed hot pool temperature distribution obtained with the two-dimensional pool model. An analysis of an unprotected transient over power with the modified reactivity model showed an improved negative reactivity feedback effect.

DEVELOPMENT OF A TWO-DIMENSIONAL THERMOHYDRAULIC HOT POOL MODEL AND ITS EFFECTS ON REACTIVITY FEEDBACK DURING A UTOP IN LIQUID METAL REACTORS

Lee, Yong-Bum,Jeong, Hae-Yong,Cho, Chung-Ho,Kwon, Young-Min,Ha, Kwi-Seok,Chang, Won-Pyo,Suk, Soo-Dong,Hahn, Do-Hee Korean Nuclear Society 2009 Nuclear Engineering and Technology Vol.41 No.8

The existence of a large sodium pool in the KALIMER, a pool-type LMR developed by the Korea Atomic Energy Research Institute, plays an important role in reactor safety and operability because it determines the grace time for operators to cope with an abnormal event and to terminate a transient before reactor enters into an accident condition. A two-dimensional hot pool model has been developed and implemented in the SSC-K code, and has been successfully applied for the assessment of safety issues in the conceptual design of KALIMER and for the analysis of anticipated system transients. The other important models of the SSC-K code include a three-dimensional core thermal-hydraulic model, a reactivity model, a passive decay heat removal system model, and an intermediate heat transport system and steam generation system model. The capability of the developed two-dimensional hot pool model was evaluated with a comparison of the temperature distribution calculated with the CFX code. The predicted hot pool coolant temperature distributions obtained with the two-dimensional hot pool model agreed well with those predicted with the CFX code. Variations in the temperature distribution of the hot pool affect the reactivity feedback due to an expansion of the control rod drive line (CRDL) immersed in the pool. The existing CRDL reactivity model of the SSC-K code has been modified based on the detailed hot pool temperature distribution obtained with the two-dimensional pool model. An analysis of an unprotected transient over power with the modified reactivity model showed an improved negative reactivity feedback effect.

Reactive Hot Melt Polyurethane Adhesives Modified by Acrylic Copolymer Nanocomposites

Cho, Youn-Bok,Jeong, Han-Mo,Kim, Byung-Kyu The Polymer Society of Korea 2009 Macromolecular Research Vol.17 No.11

A macroazoinitiator (MAI) containing a poly(ethylene glycol) (PEG) segment was intercalated in the gallery of sodium montmorillonite (Na-MMT). Acrylic monomers were polymerized using this MAI intercalated in Na-MMT to prepare the acrylic copolymer nanocomposite (AN), which is a multiblock copolymer composed of two segments, an acrylic copolymer and PEG intercalated in Na-MMT (Na-MMT/PEG). When AN was used to modify the reactive hot melt polyurethane adhesive (RHA), the acrylic copolymer segment and Na-MMT/PEG synergistically enhanced the initial bond strength evolution and reduced the set time, even when the amount of Na-MMT in RHA was < 1 wt%. The viscosity of RHA increased and the tensile properties of the cured RHA film decreased due to modification with AN. These variations were more evident as the Na-MMT content in AN was increased.

Fabrication and Properties of Reactively Hot Pressed HfB₂-HfC Ultra-High Temperature Ceramics

Lee, Seung-Jun,Seong, Young-Hoon,Baek, Seung-Su,Kang, Eul-Son,Kim, Do-Kyung The Korean Ceramic Society 2010 한국세라믹학회지 Vol.47 No.6

$HfB_2$-HfC composites were prepared by reactive hot pressing using Hf and $B_4C$ at temperatures of 1800 and $1900^{\circ}C$ for 60 min under 32 MPa in an Ar atmosphere. The reaction sequences of the $HfB_2$-HfC composite were studied through series of pressureless heat treatments ranging from 800 to $1600^{\circ}C$. The effect of size reduction of the starting powders on densification was investigated by vibration milling. Fully dense $HfB_2$-HfC composites were obtained by size reduction of the starting powders via vibration milling. The oxidation behaviour of the $HfB_2$-HfC composites at $1500^{\circ}C$ in air showed formation of a non-protective $HfO_2$ scale with linear mass gain. Examination of the mechanical properties showed that particle size reduction via vibration milling also led to improved flexural strength, hardness and fracture toughness.

Reactive Hot Melt Polyurethane Adhesives Modified by Acrylic Copolymer Nanocomposites

Youn Bok Cho,Han Mo Jeong,Byung Kyu Kim 한국고분자학회 2009 Macromolecular Research Vol.17 No.11