Mechanical and electrical properties of carbon nanotube/Cu nanocomposites by molecular-level mixing and controlled oxidation process.

Lim, Byung K,Mo, Chan B,Nam, Dong H,Hong, Soon H American Scientific Publishers 2010 Journal of Nanoscience and Nanotechnology Vol.10 No.1

<P>A molecular-level mixing and controlled oxidation process is proposed as a novel fabrication technique for the production of CNT/Cu nanocomposite powders. The fabricated CNT/Cu2O nanocomposite powders showed microstructures with homogeneous dispersion of implanted CNTs in a Cu2O matrix. The CNT/Cu2O nanocomposite powders were reduced to CNT/Cu nanocomposite powders with H2 gas and then the as-prepared CNT/Cu nanocomposite powders were spark plasma sintered to fabricate CNT/Cu nanocomposites. The mechanical properties of the Cu and the CNT/Cu nanocomposites were characterized by tensile testing before and after hot compression. Before hot compression, the CNT/Cu nanocomposites were brittle, but after hot compression both yield strength and elongation were increased, while the yield strength of the Cu was decreased after hot compression. Hot compression enhanced the ductility and strength of the CNT/Cu nanocomposites due to alignment of Cu grains and CNTs. Electrical conductivity was also enhanced due to a reduced scattering of electrons because of the alignment of the CNTs and Cu grains as well as the annealing effects of the Cu matrix.</P>

Composite Materials : THE EFFECTS OF MICROSTRUCTURAL PARAMETERS ON HIGH TEMPERATURE CREEP OF SiC / 2124Al COMPOSITES

Soon H . Hong,Kyung H . Chung 대한금속재료학회 ( 구 대한금속학회 ) 1995 Advanced Material and Processing Vol.3 No.-

Analysis of Texture and Mechanical Anisotropy of Al-Mg Alloy Sheets for Autobody Applications

Hong, Soon H .,Han, Young S .,Kang, Suk B . 대한금속재료학회(대한금속학회) 1998 METALS AND MATERIALS International Vol.4 No.3

The effect of texture on mechanical anisotropy was investigated in three commercial Al-Mg alloy sheets for autobody applications. The textures were identified using ODF (oriented distribution function) analyses of XRD pole figures. The volume fractions of existing texture components were calculated based on the Gaussian function approximation. The tensile tests were performed in different directions to the rolling direction of the sheet in order to analyze the mechanical anisotropy. The Cube and Cube_(ND) recrystallization textures were identified as dominant texture components of the Al-Mg alloy sheets. The experimental R-values were in good agreement with the prediction based on the CMTP (continuum mechanics of textured polycrystals). The mechanical anisotropy originated from Cube_(ND) texture component was weaker than that originated from Cube texture component. The anisotropy in R-value decreased with increasing the amount of random spread components and the OR value was measured as 0.01 when the random spread component was 70%. The biaxial stretchability obtained from Erichen test was enhanced with decreasing the mechanical anisotropy in Al-Mg alloy sheet.

Effects of Sintering Conditions on Mechanical Properties of Mechanically Alloyed Tungsten Heavy Alloys

Hong, Soon H .,Ryu, Ho J . 대한금속재료학회(대한금속학회) 2001 METALS AND MATERIALS International Vol.7 No.3

The effects of sintering conditions on the microstructural evolution and mechanical properties of mechanically alloyed tungsten heavy alloys were investigated. W, Ni and Fe powders were mechanically alloyed in a tumbler ball mill at a milling speed of 75 rpm, ball-to-powder ratio of 20: 1 and ball filling ratio of 15%. The mechanically alloyed powders were compacted and solid-state sintered at a temperature of 1300℃ for 1 hour in a hydrogen atmosphere. The solid-state sintered tungsten heavy alloy was subsequently liquid-phase sintered at 1470℃ with varying sintering times from 4 min to 90 min. The solid-state sintered tungsten heavy alloy showed fine tungsten particles of 3㎛ in diameter and high relative density above 99%. The volume fraction of the W-Ni-Fe matrix phase was measured, as 11% and tungsten/tungsten contiguity was 0.74 in solid-state sintered tungsten heavy alloys. Mechanically alloyed and two-step sintered tungsten heavy alloys showed tungsten particles of 6-15 ㎛ and a volume fraction of the W-Ni-Fe matrix phase of 16% and tungsten/ tungsten contiguity of 0.40. The solid-state sintered tungsten heavy alloy exhibited a yield strength of about 1100 ㎫ due to its finer tungsten particles, while it showed low elongation and impact energy due to its large tungsten/tungsten contiguity. The yield strength of two-step sintered tungsten heavy alloys increased with the decreasing of tungsten particle size and volume fraction of the W-Ni-Fe matrix.

Phenomena and Mechanism on Superplasticity of Duplex Stainless Steels

Hong, Soon H .,Han, Young S . 대한금속재료학회(대한금속학회) 2000 METALS AND MATERIALS International Vol.6 No.2

The superplasticity of Fe-24Cr-7Ni-3Mo-0.14N duplex stainless steel after being solution treated at 1350℃ followed by 90% cold rolling was investigated at 850℃ with a strain rate ranging from 10^(-3)-10^(-1)s^(-1). The microstructure of duplex stainless steel consists of a matrix y phase having low angle grain boundaries and a 6 phase as second phase particles before the deformation at 850℃. It is well known that the constituent phases in duplex stainless steel is changed following α→α+γ→α+γ+σ→γ+σ through phase transformation during deformation at 850℃. The final microstructure of duplex stainless steel consisted of 70 vol.% of γ and 30 vol.% of the σ phase. A maximum elongation of 750% was obtained at 850℃ with a strain rate of 3.16×10^(-3)s^(-1).. The dislocation density within matrix γ grains was low and a significant strain-induced grain growth was observed during the deformation. The misorientation angles between the neighboring γ grains increased as the strain increased, thus the low angle grain boundaries were transformed into high angle grain boundaries suitable for sliding by dynamic recrystallization during the deformation at 850℃. The grain boundary sliding assisted by dynamic recrystallization is considered to be a controlling mechanism for superplastic deformation at 850℃.

Cell Sensing Margin of Lead-Free (Bi,La)₄Ti₃O₁₂Thin Film Deposited on MTP Cell Structure in High Density FeRAM Device

Choi, J.H.,Yoo, H.S.,Cho, K.W.,Kim, N.K.,Oh, S.H.,Choi, E.S.,Yeom, S.J.,Sun, H.J.,Lee, S.S.,Lee, K.N.,Hong, Suk Kyoung,Hong, Tae Whan,Kim, Il Ho,Ryu, Sung Lim,Kweon, Soon Young Trans Tech Publications, Ltd. 2006 Materials science forum Vol.510 No.-

<P>A 16Mb 1-transistor /1-capacitor (1T1C) FeRAM device was fabricated with lead-free Bi3.25La0.75Ti3.0O12 (BLT) capacitors. The key integration processes contain a scalable MTP (Merged Top-electrode and Plate-line) cell structure and reliable BLT ferroelectric capacitors. Ferroelectric properties of BLT films were optimized on the newly developed MTP cell structure. BLT films were coated on Pt/IrOx/Ir bottom electrode using sol-gel solutions. The composition of the optimized BLT film was about Bi3.25La0.75Ti3.0O12. The switchable polarization obtained in a 100nm-thick BLT film was about 20 µC/cm2 at the 3 V applied voltage, and the optimized BLT film showed a few fatigue losses about 10% up to 1 × 1011 cycles. The imprint properties of the BLT film were also characterized at 25°C and 90°C operating temperature after 125°C data storage. The average cell signal sensing margin between data '1' and data '0' was measured to be about 900 mV, which is a sufficiently large margin for device operation.</P>

Conformal coating of titanium suboxide on carbon nanotube networks by atomic layer deposition for inverted organic photovoltaic cells

Jin, Sung H.,Jun, Gwang H.,Hong, Soon H.,Jeon, Seokwoo Elsevier 2012 Carbon Vol.50 No.12

<P><B>Abstract</B></P><P>We propose a new strategy for improving the charge selectivity of carbon nanotubes (CNTs) for organic photovoltaic cells (OPVCs). The strategy involves the coating of an ultrathin layer of titanium suboxide (TiO<SUB>x</SUB>) on CNTs by atomic layer deposition (ALD). ALD can facilitate that conformal and uniform coating of TiO<SUB>x</SUB> on CNT networks while preserving their nanoporous structure. We used the TiO<SUB>x</SUB>-coated CNT networks as an electron transport layer in inverted OPVCs. TiO<SUB>x</SUB>-coated CNTs can provide electrons with an extremely fast conductive path through CNTs and selectively block the holes by means of the hole-barrier property of the TiO<SUB>x</SUB> in OPVCs. The nanoporous structure of TiO<SUB>x</SUB>-coated CNT networks can improve the device performance of OPVCs due to synergetic effects of the electron selective transport property of TiO<SUB>x</SUB> and the high conductivity of CNTs. In addition, further improvement of device performance can be achieved by adding a hole transport layer (MoO<SUB>3</SUB>) between the active layer and the Au electrode.</P>

Screening of Pyrus Species Resistant to Pear Psylla (Cacopsylla pyricola)

Il Sheob Shin,Dong Soon Kim,Seong Sik Hong,Jeong Hee Kim,Kang Hee Cho,Se Hee Kim,Hyun Ran Kim,Dae Hyun Kim,Se Jin Hong,Jeong Hwan Hwang,Hae Sung Hwang 한국국제농업개발학회 2011 韓國國際農業開發學會誌 Vol.23 No.5

꼬마배나무이 (Cacopsylla pyricola)에 저항성 품종육성을 위한 육종재료를 선발코자 월동형 성충수, 단과지내의 산란수, 과총엽내의약충수 및 수관 전체적인 그을음 발생정도를 15개 종 및 종간잡종133개 유전자원을 대상으로 조사하였다. 월동형 성충수는 Pyrus.calleryana 4.6마리, 단과지내 산란수는 P. calleryana 0.3개, 과총엽내약충수는 P. calleryana 0마리, 그리고 그을음 발생정도는 P.betulaefolia, P. calleryana, P. communis, P. hybrid (P.pyrifolia × P.communis), P. lindleyi 0으로 발생 및 피해정도가 가장 낮았으며 종간의 차이가 뚜렷하였다. 전체적으로 대목으로 이용하고 있는 콩배인P. calleryana와 P. betulaefolia가 조사 대상 유전자원 중 가장 높은 항객성(antixenosis)을 보였으나 품질개량에 많은 기간이 요구됨에 따라 실용적으로는 서양배(P. communis) 중 ‘Conference', 'Cascade','Bosc', 'Winter Nelis' 가 가장 낮은 발생 및 피해정도를 보여 꼬마배나무이 저항성 품종 육성을 위한 좋은 육종재료로 판단되었다. Breeding for pear resistance to pear psylla (Cacopsylla pyricola) is one of important objective of the National Institute of Horticultural and Herbal Science breeding program. One hundred thirty three accessions from 15 Asian, Chinese and European pear species were investigated for their resistance against pear psylla. The pear psylla resistance was determined based on the following four characteristics: overwintering adult population, the number of eggs and nymphs, and the degree of soot. The different pear species showed varied resistance to pear psylla. Pyrus calleryana and P. betulaefolia indicated the highest antixenosis as ovipositional preference and antibiosis as nymphal feeding and were the most resistant genetic resources. Likewise the European pears (P. communis), ‘Conference’ and ‘Cascade’, exhibited little occurrence and damage by pear psylla. These were proved to be promising genetic materials for breeding resistant cultivars because they had good fruit quality and showed resistance to pear paylla. The observed population of overwintering adult , the number of eggs and nymphs of psylla had significant correlation each other.

Radical Scavenging Effects of Propolis collected in Korea

Soon-ok Woo,In-pyo Hong,Sang-mi Han,Yong-su Choi,Ha-sik Sim,man-young Lee,Myoung-lyeol Lee 한국응용곤충학회 2013 한국응용곤충학회 학술대회논문집 Vol.2013 No.10

Propolis, bee glue is a sticky substances, which is used to prevent corruption of the ones who broke into the hive, and which is known as a substance that inhibits the growth of microorganisms within the hive. In order to use this propolis, is required to extract the active ingredients from the raw propolis. Mainly goes through the process of extraction with ethanol. Propolis is registered as health functional food for food and drug safety with a valid registration which is anti-oxidant effects and anti microbial effects of oralflora. Inthis study, in order to determine the antioxidant effect of propolis produced in various regions collected 58 regions. Antioxidant effects were tested by DPPH free radical scavenging effects method. Asa result, the propolis concentrations by 10, 50, 100, 500, 1000㎍ were 43, 73, 78, 82, and 73%, in Gangwon province, Gyeonggi Province, 57, 83, 83, 79, and 71%, Chungcheong Province, 55, 80, 80, 76, and 68%, Jeolla province 48, 75, 78, 78, and 71%, Gyeongsang province 47, 77, 81, 79, and 71%, respectively. More than a certain concentration was to determine antioxidant falling rather. These results can be said to suggest if you use the edible excess should be avoided.

Nanostructural analysis of trabecular bone

Hong, Sun Ig,Hong, Soon Ku,Kohn, David H. Springer-Verlag 2009 Journal of materials science, Materials in medicin Vol.20 No.7