bluuebunny/crossref_metadata_2025 huggingface dataset:
STUDY ON THE PIT GROWTH DURING CORROSION FATIGUE OF ALUMINUM ALLOY
Authors: ISHIHARA S. , SAKA S. , NAN Z. Y. , GOSHIMA T. , SHIBATA H. , DING B. L.
Published: November 2006

Tension-compression and rotating bending fatigue tests were carried out using aluminum alloy 2024-T3 in 3% sodium chloride solution. During corrosion fatigue process, many corrosion pits were initiated at the early stage, and cracks were initiated from the pits. The characteristics of the pit growth were investigated in detail. The critical condition for crack initiation from the corrosion pit was also studied. Crack initiation periods during corrosion fatigue were evaluated on the basis of the corrosion pit growth law.
TEXTURE STUDIES AND COMPRESSION BEHAVIOUR OF APPLE FLESH
Authors: JAMES BRYONY , FONSECA CELIA
Published: November 2006

Compressive behavior of fruit flesh has been studied using mechanical tests and microstructural analysis. Apple flesh from two cultivars (Braeburn and Cox's Orange Pippin) was investigated to represent the extremes in a spectrum of fruit flesh types, hard and juicy (Braeburn) and soft and mealy (Cox's). Force-deformation curves produced during compression of unconstrained discs of apple flesh followed trends predicted from the literature for each of the "juicy" and "mealy" types. The curves display the rupture point and, in some cases, a point of inflection that may be related to the point of incipient juice release. During compression these discs of flesh generally failed along the centre line, perpendicular to the direction of loading, through a barrelling mechanism. Cryo-Scanning Electron Microscopy (cryo-SEM) was used to examine the behavior of the parenchyma cells during fracture and compression using a purpose designed sample holder and compression tester. Fracture behavior reinforced the difference in mechanical properties between crisp and mealy fruit flesh. During compression testing prior to cryo-SEM imaging the apple flesh was constrained perpendicular to the direction of loading. Microstructural analysis suggests that, in this arrangement, the material fails along a compression front ahead of the compressing plate. Failure progresses by whole lines of parenchyma cells collapsing, or rupturing, with juice filling intercellular spaces, before the compression force is transferred to the next row of cells.
ELASTIC PROPERTY PREDICTION OF THE STITCHED MULTI-AXIAL WARP KNIT FABRIC COMPOSITES
Authors: CHUN HEOUNG-JAE , KIM HYUNG-WOO , BYUN JOON-HYUNG
Published: November 2006

In order to improve the resistances to delamination, damage tolerance, some in-plane and out-of-plane properties of composite materials, a through-thickness reinforcement must be provided. This through-thickness reinforcement is achieved by stitching multi-axial warp knit (MWK) fabrics used as preforms for the fabrication of composite materials. The MWK fabrics are constructed with layers of insertion fiber bundles in the warp, weft and bias directions. In order to correlate the microstructure of a preform with the elastic properties of stitched MWK composite, the analytical model for stitched MKW composite is developed. The overall geometry and geometric parameters of a representative volume are determined from the photomicrographs of cross sections of the fabricated composite specimens. The various elastic properties of MWK fabric composites are predicted as functions of various geometric parameters using an averaging method. The experimental results are compared with the predicted results in order to validate the suggested model. It is found that the predicted elastic properties are in reasonably good agreement with the experimental values.
PIEZOCERAMIC MATERIALS AS ENABLERS OF NEW TECHNOLOGY DEVICES
Authors: HAEMMERLE E. , LEUNG M. , GAO W. , YOO J.
Published: November 2006

Micro-tubes made out of improved lead zirconate titanate (PZT) material are used to develop a new optical switch. These PZT micro-tubes are being manufactured by an electrophoretic deposition process (EPD). EPD overcomes some of the processing problems of other conventional processing techniques. PZT tubes with less than 1mm outer diameter were fabricated successfully with EPD. The analysis of various design concepts and deflection characteristics of the micro-tube show that with an inner diameter of 130 μm and a wall thickness of 330 μm the switching concept is feasible, assuming certain achievable values for the length of the tube, piezoelectric constant and excitation voltage. A test bed for measuring the deflection of the tubes was also developed.
EFFECTS OF La, MISCH METAL ADDITIONS ON ROLLING TEXTURE IN HIGH Mg CONTENT Al-Mg ALLOYS
Authors: PARK SU-DONG , LEE HEE-WOONG , KIM BONG-SEO , PARK NO-JIN
Published: November 2006

In the present works, the change of a rolling texture by La or Mm (Misch metal) addition in high Mg content (>5wt%) Al - Mg alloy was investigated. By Mm addition, B (Brass) orientation {011} 〈112〉 was typically developed with Mg contents and it was accelerated by La , Mm additions. TC (twin copper) orientation {255} 〈511〉 and G (Goss) orientation {110} 〈001〉 orientations closely related mechanical twinning were decreased in intensity and development of coarsen share bend was suppressed by Mm addition in Al -10wt% Mg alloy. And it caused improvement of formability by Mm addition in high Mg content Al - Mg alloy.
RECOVERY AND EXTRACTION OF HEAVY METAL IONS USING IONIC LIQUID AS GREEN SOLVENT
Authors: KUMANO MASAMI , YABUTANI TOMOKI , MOTONAKA JUNKO , MISHIMA YUJI
Published: November 2006

Ionic liquids are expected to replace conventional organic solvents in organic synthesis, solvent extraction and electrochemistry due to their unique characters such as low volatility, high stability and so on. In this work, N , N ,-diethyl- N -methyl- N -(2-methoxyethyl) ammonium bis(trifluoromethansulfonyl)imide was used as an alternative solvent to extract heavy metal ions. As the extracting conditions, the additional effect of 8-hydroxyquinoline (8-HQ) as metal chelating agent into ionic liquids, shaking time and volume ratio were investigated. As extraction efficiency depended on 8-HQ concentration significantly, in order to extract high concentrated metal ions the solubility of 8-HQ into ionic liquid was tested. N , N ,-diethyl- N -methyl- N -(2-methoxyethyl) ammonium bis(trifluoromethansulfonyl)imide had good solubility of 8-HQ. Consequently, 5 μmol of copper, zinc, cadmium and manganese could be completely recovered with 100 μl of ionic liquid.
ELECTROCHEMICAL EVALUATION OF THE POLYMER MODIFIED MICRO-ELECTRODE FOR METAL IONS
Authors: MOTONAKA JUNKO , YABUTANI TOMOKI , MINAGAWA KEIJI , MISHIMA YUJI
Published: November 2006

A porous micro-electrode with immobilized poly(methacryroyl alanine) (PMA) was developed for measuring copper(II) ion ( Cu 2+) and cadmium(II) ion ( Cd 2+). A porous carbon material was packed into the tip of the platinum micro-electrode with a cavity at the top. The porous micro-electrode was dipped in the coating dimethyl sulfoxide solution with PMA and di-2-ethylhexyl phthalate and dried overnight at room temperature. The immobilized PMA on the porous micro-electrode had predominantly a keto form in the buffer solution. In the enol form a metal complex can be formed under the simultaneous liberation of a proton. Calibration curves for measurements of Cu 2+ and Cd 2+, the effects of preconcentration condition, scan rate, pH, and temperature, and lifetime of the PMA modified micro-electrode were examined. Under optimal conditions, the responses of sensor were linear in the concentration range 0.0001~1 mmol 1-1 for Cu 2+ and 0.01~1 mmol 1-1 for Cd 2+. Analytical values determined with the modified electrode were constant for at least 3 month.
CHARACTERIZATION OF Bi2Te3 THIN FILMS FOR APPLICATION IN MICRO-THERMO ELECTRIC COOLERS
Authors: HAN SEUNG WOO , HASAN MD ANWARUL , CHO KI-HO , LEE HAK JOO , KIM DONG-HO , LEE HYUN WOO
Published: November 2006

In this study we have characterized the mechanical and electrical properties of Bi 2 Te 3 thin films prepared by co-sputtering method. The film structure and morphology were revealed using the X-ray diffraction and scanning electron microscopy (SEM). Thickness of the deposited films was measured using SEM observation after FIB (Focused Ion Beam) milling, and the surface roughness of the films was analyzed using AFM (atomic force microscopy). Electrical transport properties were measured with a Hall effect measurement system, while the mechanical properties were evaluated using nanoindentation test method. Results showed that Bi 2 Te 3 thin films have amorphous structure at lower film thicknesses, but as the thickness increases the structure becomes polycrystalline. Surface roughness and crystal size of the films increased with increase in substrate temperature. Films showed higher elastic modulus and hardness values compared to those of the bulk Bi 2 Te 3 alloy. The electrical transport properties of the films were also affected by the substrate temperature.
EFFECT OF THE DEGREE OF RESTRAINT AGAINST THERMAL EXPANSION AND CONTRACTION ON WELDING RESIDUAL STRESS
Authors: LEE SANG-HYONG , CHANG KYONG-HO , JANG GAB-CHUL
Published: November 2006

Steel bridges increased considerably since 1960's in Japan. That is due to the lightness and long trend in bridge construction. Bridges, which are damaged by an increase in vehicle load, corrosion, earthquake, and so on, need repairing or strengthening. Repair procedures of steel bridge generally include cutting, bolting and welding procedures. These procedures, cutting, bolting and welding, occasionally bring about a stress concentration within the limit range. So, a chain of confirmation against the safety of structure is necessary. A safety evaluation method, which has regard to heat effect, is necessary to repair damaged structure with welding. Generalized welding residual stress is useful employ, to estimate the safety of structure during the repair work with welding. This research investigates the features of thermal stress generated by welding. The pattern of welding residual stress distribution was classified according to the ratio between length and width of plate. With those results, the features of residual stress generated by welding were generalized.
SOLUBILITY MEASUREMENTS OF TETRAGONAL LYSOZYME CRYSTALS
Authors: SUZUKI YOSHIHISA , ARAI ATSUTO , TAMURA KATSUHIRO
Published: November 2006

Solubility of tetragonal lysozyme crystal was measured by using two different methods. The solubility measured by using growth rates of the crystal corresponded well to that measured by using change in the concentration of the supernatant of the solution. Our data also corresponded well to the data obtained by Sazaki et al. and Gray et al., while not to those obtained by Howard et al. and Rosenberger et al. The discrepancies are due to the difference in the principles of the methods. We also checked effects of different initial concentrations on the solubility. Contrary to previous reports, the solutions of the different initial concentrations did not reach equilibrium when their concentrations attained to a same value.
MODELING OF SEMISOLID STRUCTURE FORMATION IN CONTROLLED NUCLEATION METHOD
Authors: YAO X. , WANG H.
Published: November 2006

Modeling the semisolid structure formation is of significance in both understanding the mechanisms of the formation of such structure and optimization of the solidification conditions for the required structure. A modified cellular automaton (mCA) model has been developed, which is coupled with macroscopic models for heat transfer calculation and microscopic models for nucleation and grain growth. The mCA model is applied to Al - Si alloys, one of the most widely used semisolid alloys. It predicts microstructure morphology and grain size during semi-solid solidification, and determines the effects of poring temperature and mould temperature on the final microstructure. The simulated results are compared with those obtained experimentally. The resulting simulations give some insight into the mechanisms about the semisolid structure formation in Controlled Nucleation process.
LUMINESCENT PROPERTIES OF (Y,Gd)3Al5O12:Ce PHOSPHORS PREPARED BY CITRIC-GEL METHOD
Authors: MORIGA TOSHIHIRO , SAKANAKA YUTA , MIKI YOSHINORI , MURAI KEI-ICHIRO , NAKABAYASHI ICHIRO
Published: November 2006

Y 3 Al 5 O 12: Ce and ( Y , Gd )3 Al 5 O 12: Ce powder phosphors were prepared by a citric-gel method by using metals nitrates as starting materials and citric acid as a complexing agent. Single phase of Y 3 Al 5 O 12: Ce was obtained by firing a precursor of the metal-citrate complexes at as low as 1000°C for 5 hours. All the Y 3 Al 5 O 12: Ce phosphors showed broad emission peaks in the range of 480-650nm and had the maximum intensity at 529nm, which were stimulated by blue-LEDs. Excitation spectra of Y 3 Al 5 O 12: Ce with different concentrations of Ce showed that the optimum amount of the doping was 1mol% for best luminescence. The photoluminescent wavelength of the ( Y , Gd )3 Al 5 O 12: Ce ( Ce :1mol%) increased monotonically with increasing the amount of Gd concentration (up to 560nm for Gd 3 Al 5 O 12: Ce ), in accordance with a linear increase of their lattice constant (e.g. 12.01Å for Y 3 Al 5 O 12: Ce and 12.11Å for Gd 3 Al 5 O 12: Ce ).
STUDY OF COPPER DIFFUSION IN LOW-k THIN FILM USING SIMS
Authors: AW K. C. , SALIM N. T. , GAO WEI , PRINCE K.
Published: November 2006

The aim of this paper is to study Cu diffusion in polymethylsiloxane (LKD-5109) low-k dielectric material manufactured by JSR Micro with respect to applied thermal energy acting alone. Previous study on low-k dielectric thin film uses a combination of electrical and thermal stress to study Cu diffusion producing a combined activation energy. In this paper, a secondary-ion mass spectrometry (SIMS) was used to determine copper diffusion into LKD-5109 thin film on samples baked/annealed at different temperatures ranging from 373K to 573K in forming gas (7% H 2/93% N 2). The results showed that the thermal activation energy (Ea) of Cu thermal diffusion is approximately 0.14eV for baking/annealing temperature ranging from 373K to 523K. The Ea will increase to greater than 0.58eV for temperature above 523K with Cu oxidation. The increase in Ea suggests a transport mechanism due to Cu oxidation where oxidized Cu is a source of copper ions that diffused through the low-k dielectric film.
TO DEVELOP NANOSTRUCTURED THERMAL BARRIER COATINGS
Authors: WANG NING , ZHAO WEIXUN , WANG PING , WEI ZHENG
Published: November 2006

Advanced turbine engines require the application of thermal barrier coatings (TBCs) to provide still higher reliability, thermal insulation effect and longer lifetime under harsh operating conditions. TBCs with nanostructure proved to be promising to deliver the desired property and performance. To exploit full potentials of the current widely used yttria-partially-stabilized zirconia (YSZ), nano-sized YSZ powders were developed and used as the ceramic source material. By controlling the deposition processes, novel TBCs with outstanding nanostructure such as nano-sized grains and pores were produced by atmospheric plasma spray (APS) and electron beam physical vapor deposition (EB-PVD), respectively. The incorporated nanostructure in TBCs resulted in substantial increase in thermal barrier effect and their lifetime. The long-term microstructure stability of the nanocoating was also investigated.
COMPUTER MODELLING OF AGE HARDENING FOR ISOTHERMALLY AGED Al-Mg-Si ALLOYS
Authors: WU LINDA , FERGUSON W. GEORGE
Published: November 2006

Computer modelling, due to it saving time and money, has been widely used in industrial simulation. The present model, which is based on the Shercliff-Ashby methodology for the ageing of aluminum alloys, can be used to predict the yield strength (or hardness) of Al - Mg - Si alloys for the artificial ageing temperature below the solvus temperature as a function of time. With suitable input data, this model can be applied to most Al - Mg - Si alloys, wrought or cast. In the present model, input data for aluminium alloys of A356, A357 and 6061 is taken from the open literature, and then the unknown constants are calibrated from these data. After calibration, the ageing curves are constructed for different isothermal ageing temperatures. Finally, experimentally ageing heat treatments at different temperatures for casting alloys of A356 were done to validate the model.
PORTEVIN–LE CHÂTELIER INSTABILITY IN L10-TiAl SINGLE CRYSTAL
Authors: CHIU Y. L. , PENHOUD P. , VEYSSIÈRE P.
Published: November 2006

We studied the deformation behaviour of γ Ti -54.5% Al single crystal at temperatures ranging from 200°C to 700°C along [153] orientation, where the major operative slip system is [Formula: see text]. During this temperature regime, deformation microstructure consists of long heavily pinned screw dislocations. Serrated plastic flow has been observed at 500°C, the serration amplitude decreases with strain. The combination of the strain ageing and stress relaxation experimental results demonstrate for the first time the Portevin–Le Châtelier type instability in TiAl single crystal.
NANOSTRUCTURED TUNGSTEN-IRON ALLOY PREPARED BY ELECTRODEPOSITION
Authors: CHIU Y. L. , BALUC N. , SCHÄUBLIN R.
Published: November 2006

Tungsten-iron alloy was produced by electrodeposition. The electrodeposited alloy (15 at.% W ) possesses a two-phase composite microstructure, containing a nanocrystalline phase of distorted BCC structure with a grain size between 50 to 150 nm and an amorphous phase as the matrix. TEM in-situ annealing revealed that this composite structure was stable up to 650°C. When tungsten content was doubled, the deposited alloy became amorphous.
LOW VOLTAGE SOI CMOS IMAGE SENSOR WITH PINNED PHOTODIODE ON HANDLE WAFER
Authors: CHO YONG-SOO , CHOI SIE YOUNG , TAKAO H. , SAWADA K. , ISHIDA M.
Published: November 2006

We have fabricated 32 × 32 SOI CMOS active pixel image sensor with pinned photodiode on handle wafer in order to reduce dark current, transfer charge completely, and improve spectral response. The four transistor type active pixel image sensor is comprised of reset and source follower transistors on SOI seed wafer, while the pinned photodiode, transfer gate, and floating diffusion are fabricated on SOI handle wafer. The pinned photodiode could be optimized because the process of the photodiode on SOI handle wafer is independent of the transistor process on SOI seed wafer. The optimized pinned photodiode is simulated in order to understand complete charge transfer at 3.3 V and 2.5 V of transfer gate voltage, respectively. We also investigated the optical response of fabricated active pixel image sensor under different illumination density conditions from He - Ne laser source at 3.3 V and 2.5 V of transfer gate voltage.
FRACTURE CHARACTERISTICS OF DLC ON SILICON USING NANO-INDENTATION AND FEA
Authors: BAEK SEUNG , SEOK CHANG-SUNG
Published: November 2006

In this study, using the nano and micro-indentation tests and finite element analysis (FEA), we investigated the fracture behaviors of diamond like carbon (DLC) on silicon in indentation state. Diamond like carbon coating of 3μm and 1.5μm thickness were deposited on polished (100) single crystal silicon substrates by radio frequency plasma assisted chemical vapor deposition (RF-PACVD), respectively. Fracture toughness of DLC films was calculated from the measured lengths of the cracks formed by nano and micro-indentation on each sample. We used various equations such as Lawn's and Liang's equation to calculate the fracture toughness. The effective fracture toughnesses of these DLC films were 1.2 ~1.3 MPam 0.5, calculated by Lawn's and Liang's equations. The true fracture toughness of DLC on silicon, excluding the portion of fracture toughness due to a substrate, was determined to be 4.0~5.1 MPam 0.5. DLC films with crack initiation and propagation were analyzed by finite element method.
CREEP BEHAVIOR AND LIFE EVALUATION OF AGED P92 STEEL
Authors: KIM BUMJOON , LIM BYEONGSOO , KI DONGHYUN
Published: November 2006

Creep strength and life of material is closely related with the microstructural characteristics. Components used under creep condition for long time are unable to maintain the stability of microstructure and experience degradation of material. From this viewpoint, it is necessary for safety and residual life of power plant to investigate creep properties of specimens prepared from the material cut directly from the operating service components. The small punch test has been developed as a useful method to estimate mechanical properties because of its miniaturized specimen size. In this study, small punch creep tests were carried out to investigate the effect of aging time on creep properties using P92 steel aged from 0~12100 hrs at 600°C.
EVALUATION OF CREEP-FATIGUE LIFE BY FRACTION OF CAVITY AREA
Authors: KIM BUMJOON , LIM BYEONGSOO
Published: November 2006

The components of power plant such as main steam pipe and gas turbines are operated under static and cyclic load conditions. As the period of static load increases, the service life of these components decreases. Generally, the increase of cyclic load results in fatigue damage and the increase of static load period results in the metallurgical degradation by the effect of creep. Under the creep-fatigue interaction, cavities cause rapid degradation of material and decreases the creep-fatigue life of high temperature components. In this paper, creep-fatigue tests were performed to investigate the relationship between the cavity and creep-fatigue life under various tensile hold times. Test materials were HAZ and base metal of P122 (12 Cr -2 W ) alloy weldment. The effect of hold times on the cavity damage was examined and the fraction of cavity area was analyzed. From the linear relationship of Fca (fraction of cavity area) and experimental life, a new parameter for life evaluation, Fca, was introduced and the creep-fatigue life was predicted by Fca. Good agreement was found between experimental and predicted life. Under the same hold time condition, the Fca of HAZ was greater than that of base metal while the creep-fatigue life of HAZ was shorter than that of base metal.
STUDIES ON THE ENVIRONMENTAL IMPROVEMENT IN ROMANIA
Authors: OGAKI MITSUHARU , YOSHIZUMI KOJI , MOTONAKA JUNKO , YABUTANI TOMOKI , NAKAMOTO YUMI , STANESCU RODICA , PLESCA MARINELA
Published: November 2006

In Romania, the communist planned economy system was in place for 42 years but ended due to a revolution in 1989. An environmental administration was started 1990. In order to assist with environment related activities, one of the authors worked in Bucharest for two years from March 2002 to March 2004 as a JICA (Japan International Cooperation Activity) member. One of the most important problems regarding environmental protection in Romania is waste management. In Japan, the regulations and penalties system of waste management have been used for a long time. However, there are many serious problems with the system, such as a decrease in waste disposal facilities and illegally disposed waste. The authors studied a new plan that uses a certification system in order to promote recycling industries. This system is both efficient and inexpensive so it is possible that this method of waste management could be transmitted to Romania.
CATALYTIC ACTIVITY FOR METHANE OXIDATION OF GOETHITE SUPPORTED ON ALUMINA
Authors: MURAI KEI-ICHIRO , TOMITA KOHEI , TOJO SUGURU , MORIGA TOSHIHIRO , NAKABAYASHI ICHIRO
Published: November 2006

Two kinds of α- Fe 2 O 3 catalysts supported on χ- Al 2 O 3 and γ- Al 2 O 3 were synthesized. α- Fe 2 O 3 was prepared from α- FeOOH . As a model experiment, an investigation was made with the oxidation of methane. As all catalysts with various Fe contents supported on χ- Al 2 O 3 with various Fe contents had higher specific surface areas than those supported on γ- Al 2 O 3, α- Fe 2 O 3/χ- Al 2 O 3 catalyst has higher catalytic activities than α- Fe 2 O 3/γ- Al 2 O 3 catalyst. From SEM-EDS analyses, it is concluded that in α- Fe 2 O 3/χ- Al 2 O 3 catalyst, α- Fe 2 O 3 exists mainly on the surface of the support, because of flatness of the surface of χ- Al 2 O 3. On the other hand, in the case of α- Fe 2 O 3/γ- Al 2 O 3 catalyst, as the surface of support, γ- Al 2 O 3, is uneven, α- Fe 2 O 3 do not partially exist on the surface but in the pores.
ELECTRONIC STATE CALCULATION OF MANGANESE DIOXIDE ELECTRODE WITH ADDITIVE TRANSITION METALS
Authors: KIM BONG-SEO , PARK SU-DONG , LEE HEE-WOONG , LEE DONG-YOON , CHUNG WON-SUB
Published: November 2006

The electronic states of manganese dioxide substituted with transition metals were theoretically calculated by DV-Xα method, cluster model was Mn 15 O 56 and Mn 14 XO 56 (X = transition metal). The energy band gap of manganese-X oxides is lower than that of manganese dioxide from theoretical calculation. Also it is identified that the electrical conductivity of manganese-tungsten oxide is better than that of manganese dioxide from experiment of anodic deposition method. It is confirmed that the theoretical calculation coincides with experimental results.
HIGH TECHNIQUE FOR T-PEEL STRENGTH ENHANCEMENT OF Al/AFRP HYBRID COMPOSITE
Authors: KIM CHEOL-WOONG , OH DONG-JOON
Published: November 2006

The interlaminar peel strength of Al / AFRP (Aluminum alloy/Aramid Fiber Reinforced Plastic) hybrid composite is affected by the adhesive strength between the Al alloy layer and the aramid fiber layer. The study of the tensile strength and the T-peel strength of the Al / AFRP should be accomplished first. Therefore, this study focused on the effect of the resin mixture ratio as the Al / AFRP on the tensile strength and T-peel strength. In conclusions, the resin mixture ratio by equivalence ratio of 〈epoxy resin : curing agent〉 equal to 〈1:1〉 of Al / AFRP -I and the resin mixture ratio by equivalence ratio of 〈epoxy resin : curing agent : accelerator〉 equal to 〈1:1:0.2〉 of Al / AFRP -II showed the highest ultimate tensile strength. After the T-peel test, it is found that the T-peel strength of Al / AFRP -II is approximately 1.5 times higher than that of Al / AFRP -I. Reviewing the characteristics of the tensile and T-peel strengths, the resin mixture ratio 〈1:1:0.2〉 of Al / AFRP -II showed the highest tensile strength and T-peel strength.
NON-DESTRUCTIVE EVALUATION AND STRENGTH CHARACTERISTICS OF CFRP WITH HEAT DAMAGE
Authors: KIM JIN WOOK , KIM YOUNG UN , MOON CHANG KWON , AHN SEOK HWAN , NAM KI WOO
Published: November 2006

In this study, the heat-damage process of a carbon fiber reinforced plastic (CFRP) under monotonic tensile loading was characterized by acoustic emission. Additionally, epoxy specimens and prepreg specimens were used to determine the characteristics of acoustic emission (AE) signals of epoxy and fiber, respectively. The AE characteristics of CFRP showed three types of distinct frequency regions. Time-frequency analysis methods were employed for the analysis of fracture mechanisms in CFRP such as matrix cracking, debonding and fiber fracture. To evaluate the cumulative counts of AE signals, it seems that the results can be applied usefully to guarantee structural integrity and/or to the survey of destruction of the structure with heat-damage, that was made to the composite materials.
A STUDY ON DAMAGE BEHAVIOR OF GLASS BY OBLIQUE IMPACT OF STEEL BALL
Authors: SUH CHANG-MIN , KIM DONG-KYUN , LEE MOON-HWAN
Published: November 2006

The damage behavior of soda-lime glass was studied by oblique impact test with a steel ball, and in order to investigate the effect of roughness damage on glass, variable damages and strength degradation of smooth and Al 2 O 3 sand blasted for roughness glass was investigated by the ball impact test. After the test, the crack patterns were investigated using a stereo-microscope. In addition, the finite element method was performed to analyze the stress distribution and variation in the glass impacted obliquely by the steel ball. As a result of the impact test, the crack length of 90° impacted glass was the largest and that of 50° impacted glass was the smallest. In particular, as the impact velocity and diameter of the steel ball increased, the difference in crack length was prominent. The finite element analysis showed the maximum principle stresses distribution in the contact area of glass specimen. The result of analysis was accorded with the crack growth behavior by the oblique impact test.
NANO-INDENTER MECHANICAL PROPERTIES OF ITO/GLASS THIN FILM DEPOSITED BY DC MAGNETRON SPUTTERING METHOD AT LOW TEMPERATURE
Authors: YOON HAN-KI , KIM DO HYOUNG , SHIN DO HOON , MURAKAMI RI-ICHI
Published: November 2006

The ITO film was deposited onto the glass substrate at room temperature by the inclination opposite target type DC magnetron sputtering equipment. An indium tin alloy ( In 2 O 3(90 wt %)+ SnO 2(10 wt %)) target was used. The Total sputtering pressure was varied from 2.6×10-1 to 8.3×10-1 Pa . The experimental result showed that the ITO film produced at room temperature had microstructure in which a X-ray diffraction peak is not clear, regardless of the total sputtering pressure. All the films showed a high optical transmittance. The ITO films prepared at low pressures gave low electrical resistivity. The elastic modulus and hardness of ITO films on various total sputtering pressures were increased with decreasing the total sputtering pressure and this tendency was similar to the change in electrical resistivity with decreasing the total sputtering pressure.
EVALUATION METHOD OF GAS TURBINE BLADES COVERING INTEGRITY BY IR CAMERA
Authors: YANG DONG-JO , CHOI CHOUL-JUN , KIM JAE-YEOL
Published: November 2006

Key parts of the main equipment in a gas turbine may likely be damaged due to operation under high temperature, high pressure, high-speed rotation, etc. Accordingly, the cost for maintenance increases and the damaged parts may cause generation to stop. The surface of a blade is thermal-sprayed, using powder with main compositions such as Ni , Cr , Al , etc, in order to inhibit hot oxidation. Conventional regular maintenance of the coating layer of a blade is made by FPI (Fluorescent Penetrant Inspection) and MTP (Magnetic Particle Testing). Such methods, however, are complicated and take a long time and also require high cost. In this study, defect diagnostics were tested on the coating layer of an industrial gas turbine blade, using an infrared thermography camera. Since the infrared thermography method can check a temperature distribution by means of non-contact on a wide range of areas, it can advantageously save expense and time as compared to conventional test methods. For the infrared thermography method, however, thermo-load must be applied onto a tested specimen and it is difficult to quantify the measured data. To solve the problems, this paper includes description about producing a specimen of a gas turbine blade (bucket), applying thermo-load onto the produced specimen, photographing thermography images by an infrared thermography camera, analyzing the thermography images, and pre-testing to analyze defects on the coating layer of the gas turbine blade.
PREDICTION OF FORMABILITY FOR MAGNESIUM ALLOY SHEET USING FINITE ELEMENT POLYCRYSTAL MODEL
Authors: WON SUNG YEUN , YOU BONG SUN , KIM YOUNG SUK , YANG SEUNG HAN
Published: November 2006

In this study, in order to analyze deformation mechanism in rolling process and predict its yield surface finite element polycrystal model (FEPM) has been developed. Also numerical simulations for deep drawing process of AZ31 magnesium sheet were conducted at elevated temperature. Numerical simulation results for rolling process were compared with experiments of pole figure. For yield surface, the results indicated shift of yield surface along the biaxial strain direction denoting Bauschinger effect and strong anisotropic which is advantageous to deep drawing. Simulation results for limiting drawing ration (LDR) in cup drawing simulation agreed well with experimental observations.
EFFECT OF ULTRASONIC VIBRATIONS ON ACCELERATING HEAT TRANSFER OF PCM
Authors: YANG HO DONG , OH YOOL KWON
Published: November 2006

This study presents the effect on accelerating heat transfer of phase change material (PCM) when the ultrasonic vibrations were applied. Applying ultrasonic waves in a medium may cause the flow velocity of the medium to increase: an effect known as acoustic streaming. Hence, the objective of the present study was to investigate the melting process of a PCM from a heated vertical wall for the following: one without ultrasonic vibration (natural melting) and the other ultrasonic vibrations. The heat flow was measured in the absence of and in the presence of acoustic streaming. The streaming created by ultrasonic vibrations was visualized by a particle image velocimetry (PIV) and a thermal infrared camera. The experimental results revealed that acoustic streaming could accelerate the melting process as much as 2.5 times. Also, total consumed electricity was saved about 2.3 ~ 2.8 Wh , compared to the rate of natural melting. Moreover, we investigate the relationship between acoustic pressure variations and enhancement of heat transfer applying for coupled finite element-boundary element method (Coupled FE-BEM) as a numerical analysis. From the result study, as the acoustic pressure increases, the higher enhancement ratio of heat transfer is obtained. In the end, acoustic pressure variations are related to the acceleration of heat transfer by ultrasonic vibrations.
CHARACTERIZATION OF TRIS (8-HYDROXYQUINOLINE) ALUMINUM (Alq3) FILM USING SPECTROSCOPIC ELLIPSOMETRY
Authors: CHO YONG JAI , KIM HYUN JONG , CHEGAL WON , CHO HYUN MO , BAEK UN BONG , NAHM SEUNG HOON , LEE JEONG-IK , CHU HYE YONG
Published: November 2006

We have applied spectroscopic ellipsometry to obtain the optical constants, i.e., refractive indices (n) and extinction coefficients (k) of a thin tris (8-hydroxyquinoline) aluminum ( Alq 3) film evaporated on the top of 300-nm-thick SiO 2 layer on a silicon substrate. Using a spectroscopic ellipsometer we collected the ellipsometric data of Ψ and Δ at 3 incident angles of 65°, 70° and 75° and 226 energies of 1.5 eV to 6.0 eV. For the organic sample, we adopted a simple two-film model consisting of ambient/organic film/ SiO 2 film/silicon substrate. Using the multiple oscillators of Tauc-Lorentz (TL) dispersion function and the two-film model, we obtained the thickness of the Alq 3 film. By data inversion technique, the spectra of n and k for the Alq 3 film are calculated from measured Ψ and Δ at each photon energy when the film thickness is fixed to a value obtained by the TL dispersion fitting. The extrapolation of optical function near band gap yields the band gap of 2.64 eV for Alq 3 film.
FRACTURE BEHAVIOR OF Zr-BASED BULK METALLIC GLASS UNDER IMPACT LOADING
Authors: SHIN HYUNG-SEOP , KIM KI-HYUN , OH SANG-YEOB
Published: November 2006

The fracture behavior of a Zr -based bulk amorphous metal under impact loading using subsize V-shaped Charpy specimens was investigated. Influences of loading rate on the fracture behavior of amorphous Zr - Al - Ni - Cu alloy were examined. As a result, the maximum load and absorbed fracture energy under impact loading were lower than those under quasi-static loading. A large part of the absorbed fracture energy in the Zr -based BMG was consumed in the process for crack initiation and not for crack propagation. In addition, fractographic characteristics of BMGs, especially the initiation and development of shear bands at the notch tip were investigated. Fractured surfaces under impact loading are smoother than those under quasi-static loading. The absorbed fracture energy appeared differently depending on the appearance of the shear bands developed. It can be found that the fracture energy and fracture toughness of Zr -based BMG are closely related with the extent of shear bands developed during fracture.
THE STRUCTURAL DESIGN FOR HYPER-ELASTIC MATERIALS USING CFD ANALYSIS
Authors: PARK YOUNG-CHUL , JUNG DAE-SEOK , KIM JI-YOUNG
Published: November 2006

The usage of hyper-elastic material has been increasing gradually and its application has extended over a wide range of various industries. Implementing experimental and numerical methods, performance of hyper-elastic material can be predicted. Proposed in this study is the process by which the material coefficient can be obtained and applied to seat-ring of butterfly valve. Considering the mechanical properties and material conditions, optimum model was constructed and applied to obtain the coefficient by using CFD analysis.
MAGNETIC PROPERTIES OF Ni NANOPARTICLES
Authors: JEON Y. T. , MOON J. Y. , LEE G. H. , PARK J.
Published: November 2006

We investigated the size dependent magnetic properties of Ni nanoparticles. We prepared four samples with average particle diameters of 7.0, 14.0, 16.5, and 20.0 nm. The blocking temperatures (TBs) were 40.0, 150.0, 250.0, and ~ 300.0 K for the above Ni nanoparticles, respectively. Saturation magnetization increased with increasing particle diameter due to the reduced magnetic moments of surface atoms. The coercivities at 5 K ranged from 270 and 340 Oe, whereas those at 300 K were zero due to superparamagnetism.
FeCo AND FeCr BINARY NANOCLUSTER WIRE (NCW) ARRAYS
Authors: HUH S. H. , JEONG J. W. , JEON Y. T. , MOON J. Y. , LEE G. H. , PARK J.
Published: November 2006

We produced FeCo and FeCr binary nanocluster wire (NCW) arrays by thermally decomposing mixtures of Fe ( CO )5/ Co 2( CO )8 and Fe ( CO )5/ Cr ( CO )6 metal carbonyl vapors, respectively. For both FeCo and FeCr binary NCW arrays, the diameters of individual NCWs ranged from 10 to 30 nm and the NCWs existed as bundles. For both FeCo and FeCr binary NCW arrays, we observed lower saturation magnetic fields and higher Mr/Ms for the magnetic field applied parallel to the NCWs than those for the magnetic field applied perpendicular to the NCWs, respectively. We also observed higher coercivities in FeCo binary NCW arrays than those in FeCr binary NCW arrays, due to the antiferromagnetic property of Cr .
THE EFFECT OF CARBIDES PRECIPITATION ON THE SLIDING WEAR CHARACTERISTICS ACCORDING TO HEAT TREATMENT CONDITIONS
Authors: SUH CHANG-MIN , CHOI GYE-WON , KIM KYUNG-RYUL , HAN MOON-SIK
Published: November 2006

This study investigated the effect of carbide precipitation hardening of heat-treated SK5M steel on the sliding wear resistance. The cold rolled carbon steel strip samples (J, G, and S-type) were oil quenched after tempering for optimal durations. The wear resistance was evaluated using a pin-on-disk wear test with an alumina counterface against different samples at various loads and distances with a constant running speed. The size and distribution of the precipitated carbides were observed using an image analyzer at various heat treatments. The heat-treated samples presented more dense carbide distribution in an area fraction and the decreased size of carbides. It is confirmed that the wear rate is minimum at an optimized austenitizing temperature of around 800°C. The specific wear rate indicates that the S-type sample has high wear resistance compared to that of J-Type. This is understood by stable wear behavior of S-type sample containing evenly distributed carbide precipitation.
DEVELOPMENT OF A NEW UTM (UNIVERSAL TESTING MACHINE) SYSTEM FOR THE NANO/MICRO IN-PROCESS MEASUREMENT
Authors: KWEON HYUNKYU , CHOI SUNGDAE , KIM YOUNGSIK , NAM KIHO
Published: November 2006

Micro UTM (Universal Testing Machines) are becoming increasingly popular for testing the mechanical properties of MEMS materials, metal thin films, and micro-molecule materials1-2. And, new miniature testing machines that can perform in-process measurement in SEM, TEM, and SPM are also needed. In this paper, a new micro UTM with a precision positioning system that can be fine positioning stage. Coarse positioning is implemented by step motor. The size, load output and used in SEM, TEM, and SPM have been proposed. Bimorph type PZT precision actuator is used in displacement output of bimorph type UTM are 109×64×22( mm ), about 35g, and 0.4 mm, respectively. And the displacement output is controlled in the block digital form. The results of the analysis and basic properties of positioning system and the UTM system are presented. In addition, the experiment results of in-process measurement during tensile load in SEM and AFM are showed.
NUMERICAL AND EXPERIMENTAL EVALUATION ON THE RESIDUAL STRESSES OF WELDED JOINTS
Authors: HUH SUN CHUL , PARK WONJO , YANG HAESUG , JUNG HAEYOUNG , KIM CHUYOUNG
Published: November 2006

Wings for the defense industry such as fighters, missiles, and rockets should show no deformation or damage on the structure. The structures of existing wings had holes for weight reduction. The plates and frames were fixed with rivets or screws, which limited the weight reduction possible. In this study, an improvement was made in jointing methods through EB welding and laser welding. Welding strength was measured through tension testing. In addition, finite element analysis was performed for the welding process so as to deduce the optimum welding condition.
THE STRESS ANALYSIS AND THE CRACK BEHAVIOR ACCORDING TO THE CHARACTERISTIC OF THE INTERFACIAL REGION IN FIBER REINFORCED MMC
Authors: KWON OH-HEON , KANG JI-WOONG
Published: November 2006

High performance composite reinforced with unidirectional continuous fibers are used in applications requiring high stiffness, high strength and light weight. Because of the high stiffness of the reinforced continuous fiber, the longitudinal performance of such unidirectional composites is greatly enhanced, but their transverse performance is so weak. The nature of the fiber/matrix interface is one of the important factors which determine the unique properties of the fiber reinforced metal matrix composites (MMCs). So, the current study is focused on the fracture behavior of the interface. Both stress state of the interface and crack parameters of the perpendicular crack to the interface for unidirectional fiber reinforced metal matrix composites under the transverse loading are investigated by using elastic-plastic finite element analysis. Different fiber volume fractions (5~60%) and arrangement (square and hexagon) of fibers were studied numerically. The fiber/matrix interface was treated as multi thin layer with different material properties. The fiber is assumed as linear elastic SiC and the matrix is assumed as elastic-plastic Ti -15-3 Titanium alloy. The results show that the stress distributions of the multi thin layer model have much less changes compared with a single interface case. And the properties of the interfacial zone affect the stress distribution, crack behavior and mechanical behavior of the fiber reinforced metal matrix composite.
SYNTHESIS AND CHARACTERIZATION OF NEW THERMOTROPIC LIQUID CRYSTALLINE POLYURETHANES WITH BIPHENYL MOIETY
Authors: LEE JONG BACK , LEE SANG PILL , LEE JIN KYUNG
Published: November 2006

A new series of thermotropic polyurethanes containing biphenyl units was synthesized by polyaddition reaction of diisocyanates such as 2,6-tolylene diisocyanate, 2,5-tolylene diisocyanate, 2,4-tolylene diisocyanate, and 1,4-phenylene diisocyanate, with 4,4□-bis(9-hydroxynonoxy)biphenyl (BP9). Structures of the monomer and the corresponding polymers were identified using FT-IR and 1 H NMR spectroscopic methods. BP9 exhibited a smectic type mesophase, however, nematic phase was found for all synthesized liquid crystalline polyurethanes except for 1,4-phenylene diisocyanate/BP9 based polyurethane. Their phase transition temperatures and thermal stability were investigated by differential scanning calorimetry (DSC), optical polarizing microscopy, and X-ray scattering. The infrared study indicated that the hydrogen bonding among urethane linkages attributed to the mesomorphism. Thermal gravimetric analysis (TGA) of synthesized polyurethanes showed that no weight loss of the polymers observed up to 280°C.
THE FEASIBILITY OF FLUORESCENT NANO-PARTICLE FOR BIOLOGICAL FLOW ANALYSIS IN A MICROCHANNEL
Authors: PARK CHEOL WOO , KIM GYU MAN , KIM DONG KYUN , LEE SANG JOON
Published: November 2006

The biological flow characteristics inside a microchannel were investigated experimentally using a micro-particle image velocimetry (micro-PIV) method. The main objectives of this study were to understand the blood flow in micro-domain blood vessels and to identify the feasibility of nano-scale fluorescent particles for velocity measurement. The flow field was analyzed with a spatial resolution of 1 K ×1 K pixels at low Reynolds number flow. To obtain the spatial distributions of mean velocity, 100 instantaneous velocity fields were captured and ensemble-averaged. As a result, for the case of blood flow, there were substantial velocity variations in the central region of micro-channel due to the presence of blood cells in the blood flow.
AN EVALUATION OF OPTIMAL GRINDING CONDITIONS OF ZrO2 FERRULE BY VIBRATION ANALYSIS OF THE WHEEL SHAFT
Authors: SUH CHANG-MIN , KIM SANG-CHUN
Published: November 2006

Ceramic ferrule, which is a major part of fiber optic connectors, requires a high level of precision in the grinding process. Recently, the requirements for high precision and efficiency have gradually increased to match the international competitiveness within the industrial fields of grinding machine. This trend has had a significant effect on industrial fields. In this study, the effects of the grinding conditions regarding the roundness of ZrO 2 ferrule, that apply to the optical fiber connector, were analyzed and measured using the effects of a run-out for the rotation speed of a spindle, the mesh number of a grindstone and the feed rate. Experiments were performed to determine the optimal grinding conditions according to each grinding factor.
A STUDY OF THE MECHANICAL CHARACTERISTICS OF ULTRASONIC COLD FORGED SKD61
Authors: SUH CHANG-MIN , SONG GIL-HO , PARK HAE-DOO , PYOUN YOUNG SHICK
Published: November 2006

Ultrasonic Cold Forging (UCF) technology is a method that to induces intensive plastic deformation on a material surface, so that the structure of the material becomes very fine from the surface to a certain depth. It improves the mechanical properties, hardness, compressive residual stress, and the wear and fatigue characteristics of the surface. In this study, UCF technology is applied to a cutting tool on a rolling process at a steel mill. At first, the ultrasonic cold forged specimens of SKD-61 are prepared and tested to verify the effects of UCF technology with regard to the mechanical properties, UCF is applied to the trimming knives of the cold rolling process. It is found that UCF improves the mechanical properties effectively and it is a pratical method that can improve the service time needed for the trimming knives. The productivity of the cold rolling process can be increased by the application of the ultrasonic cold forged trimming knives.
STRUCTURAL STRESS ANALYSIS ON THE RUBBER DIAPHRAGM OF AIR-OPERATED VALVE
Authors: LEE YOUNG-SHIN , CHO TAIK-DONG , KO SUNG-HO , LEE HYUN-SEUNG , SHIN SUNG-KY
Published: November 2006

Air-operated valves are used extensively in the power-generation industry for process control and system isolation functions. A study on the prevention of damage of an air operated valve is very important. Specially, diaphragm in an actuator of an air-operated valve has the highest damage rate. In this study, the stress of diaphragm with thickness change is analyzed. For this analysis, four experiments were conducted to obtain material properties of rubber. A stress analysis is carried out by commercial FEM code, ANSYS 8.0. It is compared with tension test to verify finite element analysis. From the result of analysis, the maximum stress happened at flange edge part, and the maximum displacement happened between flange edge and spring support. This study also finds out effect of the thickness about variable thickness. Even if a section area is same, the maximum stress is varied with the thickness of edge side.