bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of the shoot apex of blue spruce (Piceapungens)
Authors: Young Eric , Hanover James W.
Published: May 2008

Blue spruce (Piceapungens Engelm.) seedlings grown in a nursery for 1 to 5 years and seedlings grown from seed in a greenhouse under continuous light for 2 to 6 months were studied to determine (1) time to bud set on transfer to short days, (2) time to bud-break on subsequent transfer to long days, and (3) the anatomy of the dormant shoot apex. Seasonal development of the shoot apex of a single 50-year-old blue spruce was also monitored.Time to but set on transfer to short days decreased after long periods under continuous light. Time to budbreak on subsequent transfer to long days increased with increasing age in nursery- and greenhouse-grown seedlings. The dormant shoot apex became more highly differentiated as the nursery-grown seedlings aged from 1 to 3 years, then showed no significant difference after 3 years of age.The 50-year-old blue spruce initiated many new needles in the current bud before bud scale formation, which began in mid-May. Needle primordia initiation in the new bud began in late June and slowed down in late August. Apical dome diameter increased and decreased concurrently with the increase and decrease in rate of needle primordia initiation.
La maturité financière des peuplements forestiers au Québec
Authors: Ménard Dominic
Published: May 2008

Financial maturity rotation of stands is a new concept in the province of Quebec; it has been recently applied to some softwood and hardwood stands. In Quebec the Lands and Forest department has used the maximum of the mean annual physical growth, which does not include economic variables, to determine the optimum length of the rotation. The estimation of optimum financial length precisely considers factors such as prices, operating and management costs, and capital opportunity cost which the manager ought to use for his investment decision. In forestry, as in all other economic activities, financial maturity is a useful and important tool for determining the maximum feasibility of the present investment project.
Seasonal variations in a Douglas fir stand in total and soluble nitrogen in inner bark and root and in total and mineralizable nitrogen in soil
Authors: Driessche R. van den , Webber J. E.
Published: May 2008

Monthly sampling of stem inner bark, roots, litter, humus, and mineral soil was carried out in six 0.1-ha plots in a 47-year-old Douglas fir (Pseudotsugamenziesii (Mirb.) Franco) stand for 1 year. Pairs of plots had received urea fertilization at the rates of 0, 224, and 448 kg nitrogen (N)/ha 4 years previously. Inner bark and roots were chemically analysed to determine concentrations of total N, soluble N, ninhydrin-positive compounds, monosubstituted guanidino amino compounds, arginine, and proline. Concentration of total N was determined in litter, humus, and mineral soil samples, and concentration of mineralizable N was also determined in humus and mineral soil.All sets of data showed an effect of season, but analysis of root soluble N, root guanidino compounds, root arginine, and litter total N were the most satisfactory for distinguishing differences in N level due to fertilizer treatments. For this purpose root sampling was best done in June and July, and litter sampling between January and May. Soluble N concentration was higher in inner bark than in roots, but arginine concentration was higher in roots than in inner bark. Root arginine concentration was high in winter and decreased to a low level in October before starting to accumulate again, suggesting it behaves as a N storage compound. Litter total N showed a decrease in concentration in July and August, followed by a recovery.
Reproduction de l'épinette noire (Piceamariana) après coupe à blanc de superficie réduite
Authors: Frisque Gilles , Vézina P. E.
Published: May 2008

Small clear-cuttings (elliptical, circular, and strip) were made in the commercial boreal forest in Quebec to improve black spruce (Piceamariana (Mill.) B.S.P.) reproduction.Five years after cutting, black spruce layers were as numerous as black spruce seedlings and total softwood reproduction averaged 26 710 stems per hectare (10 810 stems per acre) with 90% stocking. In some cases, white birch stems tripled between the 1st and 5th year after cutting, which may have an important effect on stand composition.Strip cuts gave more stems per hectare than circular or elliptical cuts but stocking was lower. Strips 40 m wide (130 ft) gave better results than those 80 m wide (260 ft).Stocking, although adequate in all these small clear-cuttings, appears to be a more critical factor in the success of softwood reproduction than is density.
Ontario clay belt peatlands—are they suitable for forest drainage?
Authors: Stanek W.
Published: May 2008

Peatland types were compared to reveal differences in growth of dominant and codominant trees from undrained and artificially drained sites. The comparisons, based on tree height attained at the age of 100 years, indicate that growth improves by about 6 m in bog types and by about 4 m in fen–marsh types. To allow identification of similar sites in different localities and prediction of growth potential of sites not directly under study, 15 peatland types were assigned to five trophic groups on the basis of macronutrient content of the peat, using an automatic clustering method. The nutrient elements considered are known to influence growth on peatlands. The paper gives an account of site conditions. sampling technique, methods of comparison, and clustering. Detailed results are presented and explained.
A 400-year-old Douglas fir tree and its epiphytes: biomass, surface area, and their distributions
Authors: Pike Lawrence H. , Rydell Robert A. , Denison William C.
Published: May 2008

Methods have been developed to yield total tree estimates of biomass for various components of a tree (trunk, axes, twigs, and needles) and its community of epiphytes (microorganisms, lichens, and bryophytes). Trees were sampled with the help of climbing techniques modified from mountain climbing. Two stages of sampling were involved. First, all units of the population were described so that their weights could be predicted. Second, several units were chosen with probability of selection dependent upon predicted weight and sampled in detail. Biomass estimates from the sampled units were expanded to tree totals with information gathered during the first sampling stage. Internal structure of the crown (tree components and epiphytes) is illustrated by maps of trunk and branch systems and by diagrams of horizontal and vertical distributions. This internal structure was also derived from the first sampling stage.These methods have been applied to nine old-growth Douglas fir trees (Pseudotsugamenziesii (Mirb.) Franco). Data from a single 400-year-old tree (1.46 m dbh, 77 m in height) in the H. J. Andrews Experimental Forest in the western Cascade Mountains of Oregon are presented. Biomass and surface area estimates are as follows: trunk, 26 870 kg, 223 m2; axes (>4 cm), 1530 kg, 81 m2; living twigs (<4 cm), 480 kg, 373 m2; dead twigs, 78 kg, 104 m2; needles, 198 kg, 2860 m2; lichens, 13.1 kg; and bryophytes, 4.7 kg. Total cell volume of microepiphytes on twigs was estimated to have been 300 cm3 and total cover by microepiphytes on needles was estimated to have been 191 m2.
Sampling light intensity in a young pine plantation
Authors: Binkley S. F. , Merritt Clair
Published: May 2008

Measurements of integrated light intensity, using chemical light meters, were taken at selected height levels within and below the canopy of a closed red pine plantation to study the range of variation. A table of coefficients of variation was then prepared to facilitate estimation of statistically reliable sample sizes for each level. The greatest variation in the data was observed at a point in midcanopy. Differences were not significant between sampled levels below the live crown.
PHOTON STATISTICAL MEASUREMENT OF AFTERPULSE PROBABILITY
Authors: ZHANG GUO-FENG , DONG SHUANG-LI , HUANG TAO , LIU YUAN , WANG JUN , XIAO LIAN-TUAN , JIA SUO-TUANG
Published: May 2008

The afterpulse probability has been measured using the photon statistical method on the base of theoretical analysis for single-photon detection. It is found that the measured afterpulses obey Gaussian distribution, and the Gauss curves are left shifted with increasing incident photon intensity. We have analyzed the physical process of the phenomenon and obtained the afterpulse probability of our single-photon detector. Compared with the common start–stop method, this robust photon statistical method has the advantages of direct measurement and not requiring additional equipment.
NEW DEVELOPMENTS IN THE STUDY OFTIMEAS A QUANTUM OBSERVABLE
Authors: OLKHOVSKY V. S. , RECAMI E.
Published: May 2008

Some results are briefly reviewed and developments are presented on the study of Time in quantum mechanics as an observable, canonically conjugate to energy. Operators for the observable Time are investigated in particle and photon quantum theory. In particular, this paper deals with the hermitian (more precisely, maximal hermitian, but non-selfadjoint) operator for Time which appears: (i) for particles, in ordinary non-relativistic quantum mechanics; and (ii) for photons (i.e., in first-quantization quantum electrodynamics).
SPIN-SPLITTING OF THE BOUND POLARON'S GROUND STATE BINDING ENERGY INDUCED BY THE RASHBA SPIN–ORBIT INTERACTION UNDER THE PERPENDICULAR MAGNETIC FIELD
Authors: LIU JIA , CHEN ZI-YU
Published: May 2008

The influence of a perpendicular magnetic field on a bound polaron near the interface of a polar–polar semiconductor with Rashba effect has been investigated. The material is based on a GaAs / Al x Ga 1-x As heterojunction and the Al concentration varying from 0.2 ≤ x ≤ 0.4 is the critical value below which the Al x Ga 1-x As is a direct band gap semiconductor.The external magnetic field strongly altered the ground state binding energy of the polaron and the Rashba spin–orbit (SO) interaction originating from the inversion asymmetry in the heterostructure splitting of the ground state binding energy of the bound polaron. How the ground state binding energy will be with the change of the external magnetic field, the location of a single impurity and the electron area density have been shown in this paper, taking into account the SO coupling. The contribution of the phonons are also considered. It is found that the spin-splitting states of the bound polaron are more stable, and, in the condition of weak magnetic field, the Zeeman effect can be neglected.
RETARDATION EFFECTS IN A FINITE DIFFUSION-REACTION SYSTEM
Authors: ZABROCKI KNUD , TRIMPER STEFFEN , SCHULZ MICHAEL
Published: May 2008

The reaction-diffusion process is generalized by including spatiotemporal delay effects. As a first example, we study the influence of a constant production term which is switched off after a finite time. In a second case, all diffusion-reaction processes within a distance R(t) = κtαaround a certain spatial point are assumed to contribute to the instantaneous dynamics of the system. There occurs a competition between reaction-diffusion and the accumulation process which leads to a non-trivial stationary state. The evolving concentration profiles are calculated analytically for both a ballistic behavior with α = 1 and a diffusion-like transport with α = 1/2. Because the spatiotemporal delay breaks the reflection symmetry, the profiles reveal an anisotropic behavior. The exact solution in one dimension is supported by numerical simulations.
STRUCTURAL INVESTIGATION OF GADOLINIUM DOPED YTTRIUM-ALUMINOSILICATE GLASSES AND VITROCERAMICS
Authors: SIMON S.
Published: May 2008

Structural changes induced by heat treatment of yttrium-aluminosilicate glasses doped with gadolinium were studied by thermal differential analysis, X-ray diffraction and Gd 3+ electron paramagnetic resonance (EPR). A small amount of yttrium was replaced by gadolinium in the host glass because yttrium and gadolinium cations are quite similar, and gadolinium can be used as a structural sensor by electron paramagnetic resonance measurements. EPR results evidence small changes in the surroundings of Gd 3+ ions in the heat treated samples, as compared with the as prepared ones.
NUMERICAL SIMULATION OF OPTICAL CONFINEMENT IN ZnO BASED HETEROSTRUCTURES AT 375-NANOMETER WAVELENGTH
Authors: BHOLE M. P. , SAMUEL E. P. , PATIL D. S.
Published: May 2008

Numerical simulation of optical confinement in simple double heterostructure of ZnO / Mg x Zn 1-x O and hybrid double heterostructure of Al x Ga 1-x N/ZnO have been carried out at 375 nanometer wavelength using MATLAB. Field distribution along the junction plane has been studied as a function of mole fractions of Mg and Al for different thickness of active layers. The spread of field has been estimated as a function of mole fractions and articulated as Full Width at Half Maximum (FWHM). It was found to be decreasing nonlinearly with increase of Mg mole fraction in simple heterostructure and increasing in a nonlinear manner with increase of Al mole fraction in hybrid heterostructure. FWHM deduced from our analysis was 0.265 micron for 9% and 0.16 micron for 30% Mg mole fraction. For hybrid heterostructure, FWHM values estimated were 0.13 micron and 0.1475 micron for corresponding Al mole fraction values of 9% and 30%, respectively. The narrower confinement of field intensity around the center of the active layer for the higher values of Mg mole fraction has been attributed to an increase of refractive index step between active and barrier layers. The confinement factor as a function of mole fractions and active layer thickness has been explored, and it was found to be increasing with active layer thickness. Our analysis explores the optical confinement of mode 0 in simple and hybrid heterostructures of ZnO .
STRAIN-INDUCED BAND-MIXING EFFECTS IN ZnS/CdS (001) SUPERLATTICES
Authors: TIT NACIR , MURAT ALTYNBEK
Published: May 2008

The electronic properties of ZnS/CdS (001) superlattices (SLs) are investigated using the sp3s* tight-binding method versus substrate composition and valence-band offset (VBO). The results show that the electron is always confined within the CdS slabs; and also show a more striking feature due to the prominent localization of the top hole state near the interface region independently from the substrate composition (strain state). Theoretically, we have varied the VBO and inspected its effect on the interface state, and found that this latter persists to exist for VBO values within the interval [-1.4 eV, 0.6 eV]. This interface state is a manifestation of strong band mixing effects induced by the biaxial strain, and is expected to enhance the radiative efficiency of the SLs. The modelling of some available PL data, obtained for thin CdS quantum well embedded inside ZnS , has shown that the samples are of type-I with high energy bandgaps lying within the blue to ultraviolet spectral region.
NUMERICAL SIMULATION OF TEMPERATURE ELEVATION IN SOFT TISSUE BY HIGH INTENSITY FOCUSED ULTRASOUND
Authors: LEE KANG IL , SIM IMBO , KANG GWAN SUK , CHOI MIN JOO
Published: May 2008

In focused ultrasound surgery, high intensity focused ultrasound (HIFU) can be used to destroy pathological tissue deep inside the body without any damage to the surrounding normal tissue. This noninvasive technique has been used to treat malignant tumors of the liver, prostate, kidney, and benign breast tumors via a percutaneous or transrectal approach without the need for general anaesthesia. In the present study, a finite element method was used for the simulation of temperature elevation in soft tissue by HIFU. First, the HIFU field was modeled using the Westervelt equation for the propagation of finite-amplitude sound in a thermoviscous fluid in order to account for the effects of diffraction, absorption, and nonlinearity. Second, the Pennes bioheat transfer equation was used to predict the temperature elevation in soft tissue by HIFU. In order to verify the numerical simulation, the simulated temperature elevation at the focus in a tissue-mimicking phantom was compared with the measurements, using a concave focused transducer with a focal length of 62.6 mm, a radius of 35.0 mm, and a center frequency of 1.1 MHz.
QUANTIFICATION OF ACOUSTIC CAVITATION PRODUCED BY A CLINICAL EXTRACORPOREAL SHOCK WAVE THERAPY SYSTEM USING A PASSIVE CYLINDRICAL DETECTOR
Authors: CHOI M. J. , CHO S. C. , KANG G. S. , PAENG D. G. , LEE K. I. , HODNETT M. , ZEQIRI B. , COLEMAN A. J.
Published: May 2008

Acoustic cavitation is regarded to play an important role in extracorporeal shock wave therapy (ESWT). However it is not yet well characterized the cavitation in ESWT due to difficulty in its measurement. This study tests NPL cavitation sensor to discuss its potential to quantify cavitation activities produced by a clinical shock wave field. In the present experiment, the sensor was located at the focus of an electromagentic shock wave generator (HnT Medical System, Korea). Measurements were repeated 15 times as varying setting numbers. It was observed that the acoustic signals recorded by the sensor contain characteristic features of broadband spikes representing cavitation. Spectral band magnitude (SBM), used as a cavitation measure, rose with the setting number. There was a threshold above which SBM soared up and had its uncertainty greately increased. The results prove the potential of the sensor in characterizing the cavitation produced by shock wave fields.
ONE-SIDED ULTRASONIC CHARACTERIZATION OF CFRP COMPOSITE LAMINATES
Authors: PARK JE-WOONG , YANG IN-YOUNG , LEE KIL-SUNG , HSU DAVID K. , CHO YOUNG-TAE , SONG SUNG-JIN , IM KWANG-HEE
Published: May 2008

Ultrasonic NDE of composite laminates is usually analyzed on the backwall echoes of the specimen. In the inspection of actual composite structures, the back surface of the part was curved or contained complex geometry and did not provide a usable backwall echo. In this work, a one-sided pitch-catch setup was used in the detection and evaluation of flaws and material anomalies in solid composite laminates. Two miniature potted Rayleigh wave transducers (for generating surface waves in contact mode on steel) were joined head-to-head and used in the pitch-catch mode on the surface of composites. The pitch-catch signal was found to be more sensitive than normal incidence backwall echo of longitudinal wave to fiber orientation of the CFRP composites, including low level porosity, ply waviness, and cracks.
CYCLIC PARAMETERS GOVERNING CRACK PROPAGATION BEHAVIOR UNDER IN-PHASE AND OUT-OF-PHASE TENSILE-TORSIONAL LOADING
Authors: HUH YONG-HAK , KIM DONG-JIN , LEE HAE-MOO , LEE WAN-GUE
Published: May 2008

Cyclic fatigue parameters governing fatigue crack propagation behavior under out-of-phase biaxial fatigue loading has been investigated considering the crack propagation direction and the growth rates. The fatigue crack was propagated by employing out-of-phase cyclic tensile-torsional loads with various phase differences to the thin-walled tubular specimen. Using two crack gages mounted near a notch, the crack propagation was measured and crack opening behaviors were monitored by unloading compliance method. The directions and growth rates of the fatigue crack propagated under respective biaxial loading conditions were examined using several cyclic fatigue parameters, including equivalent stress intensity factor range, ΔKeq, crack tip opening displacement range, ΔCTD, minimum strain energy density factor range, Δ S min . It is found that the parameters, ΔCTD and Δσθθ, max , might be useful for prediction of the crack directions and the fatigue crack growth rates were relatively well correlated with ΔKeq and Δ S min . On the other hand, the crack opening levels under in-phase loading could be relatively clearly determined, while it was ambiguous to define those under out-of-phase loading.
DELAMINATION MONITORING OF QUASI-ISOTROPIC CFRP LAMINATE USING ELECTRIC POTENTIAL CHANGE METHOD
Authors: UEDA MASAHITO , TODOROKI AKIRA
Published: May 2008

Real-time detection of delamination in carbon fiber reinforce plastic (CFRP) laminates has been requiring to maintain the structural reliability of aircraft. In this paper, electric potential change method (EPCM) was applied to monitor delaminations in quasi-isotropic CFRP laminate. As the coefficient of thermal expansion and mold shrinkage factor of carbon fiber and epoxy matrix is different, residual stress is developed in the laminate during the fabrication process of curing. The local strain variation due to delaminations was measured by EPCM utilizing the piezoresistivity of the laminate itself. Finite element simulation was performed to investigate the applicability of the method.
MEASUREMENT OF THE SURFACE CONDITION OF A THERMALLY SPRAYED MATERIAL AND ITS THREE-DIMENSIONAL POSITION USING A LASER RANGEFINDER
Authors: OHTANI KOZO , SHINHARA YOSHIKO , KIDO MITSUO , BABA MITSURU
Published: May 2008

This paper describes that a measurement method for the surface condition of a thermally sprayed object and its three dimensional position with a laser rangefinder. The feature of this rangefinder is to equip an image sensor which has the ability of simultaneously detecting the position of a light and the incident angle onto the sensor. Moreover, the sensor has an autonomous exposure time control function. Therefore, our laser rangefinder can detect the 3D positions of an object with unknown reflectance. We constructed the prototype system and did some experiments to verify the proposed method. The error of the 3D position measurement was Δ z / z =0.7%. As concerns the detection of the surface condition, we could identify three types of surface roughness of a measured object with accuracy. The proposed method has great potential for a wide range of industrial inspections.
A THEORETICAL STUDY FOR PHOTOTHERMAL DEFLECTION FOR THE THERMAL CONDUCTIVITY MEASUREMENT OF ANISOTROPIC MATERIALS
Authors: JEON P. S. , KIM H. J. , YOO J.
Published: May 2008

We have analyzed the three-dimensional thermal conduction in anisotropic materials using nonsymmetric-Fourier transforms. The distribution of temperature fields which corresponds to the variation of the anisotropic ratio of thermal conductivities was obtained. The differences of the temperature fields for each material give rise to distinctions in the deflection of a probe beam. By using the relation between the temperature fields and the deflection of the probe beam, a complete theoretical treatment of the photothermal deflection has been performed for thermal conductivity measurement in an anisotropic medium. Principal and effective thermal conductivity were determined from the deflection angle and phase angle with the relative position between the heating and probe beams. The influence of the parameters, such as modulation frequency of the heating beam, the thermal conductivity, the angle between crystalline direction and probe beam direction, was investigated. Consequently, the overall effects between both thermal properties of anisotropic materials and experimental parameters and deflection signals were proposed in this study.
THICKNESS MEASUREMENT OF ALUMINUM PLATES WITH A PULSED EDDY CURRENT METHOD
Authors: KIM YOUNG JOO , AHN BONG YOUNG , LEE SEUNG-SEOK , SHIN YOUNG-KIL
Published: May 2008

In this study, coil sensors that are used with a pulsed eddy current (PEC) were designed and fabricated. The proposed sensor is a differential send-receive type that eliminates the voltage induced by the direct field from the exciting coil in a PEC probe. The signal from the sensing coil is generated only on a metal specimen. For the experiment, various metal plates of different conductivities and aluminum plates of different thicknesses from 1 mm to 25 mm were prepared. A voltage square pulse was applied to an exciting coil, and the output from the sensing coil was captured by a digital oscilloscope. The applied voltage was approximately 20 volts at its greatest with a current peak of approximately 15 amperes. A 10% variation of the thickness of an aluminum plate of 20 millimeter thick was measured.
FUNDAMENTALS OF ULTRASONIC PHASED ARRAYS
Authors: SCHMMER LESTER W.
Published: May 2008

It is shown that the wave field of an ultrasonic linear array is closely related to that of an equivalent single element transducer. Using this relationship, it is demonstrated how one can construct a simple and efficient ultrasonic beam model for the wave field of a steered linear array.
DEVELOPMENT OF SHIELDED REFLECTION TYPE PULSED EDDY CURRENT TESTING PROBES FOR THICKNESS EVALUATION
Authors: SHIN YOUNG-KIL , CHOI DONG-MYUNG , JANG KWAN-SEOB
Published: May 2008

Reflection and send-receive type probe shielded by ferrite is designed to evaluate the thickness of test plate by a pulsed eddy current (PEC) method and effects of pulse width to PEC signal are investigated when a 10.5 mm thick, nonmagnetic plate is inspected. Results show that the best sensitivity to thickness variation can be achieved by the peak value of a PEC signal. Pulse width variation study suggests that the shorter pulse width is desired if the peak value or the zero crossing time is used to evaluate the thickness, while the longer pulse width is needed if the time to peak value is used to evaluate it.
NUMERICAL MODELING OF WALL THINNING DEFECTS CHARACTERIZATION: APPLICATIONS IN LAMB WAVE GENERATION AND INTERACTION
Authors: JEONG HYUNJO , LEE SEUNG-SEOK , KIM YOUNG-GIL
Published: May 2008

The generation of axisymmetric Lamb waves and interaction with wall thinning (corrosion) defects in hollow cylinders are simulated using the finite element method. Guided wave interaction with defects in cylinders is challenged by the multi-mode dispersion and the mode conversion. In this paper, two longitudinal, axisymmetric modes are generated using the concept of a time-delay periodic ring arrays (TDPRA), which makes use of the constructive/destructive interference concept to achieve the unidirectional emission and reception of guided waves. The axisymmetric scattering by the wall thinning extending in full circumference of a cylinder is studied with a two-dimensional FE simulation. The effect of wall thinning depth, axial extension, and the edge shape on the reflections of guided waves is discussed.
MACHINE VISION MONITORING SYSTEM OF LETTUCE GROWTH IN A STATE-OF-THE-ART GREENHOUSE
Authors: LEE JONG WHAN
Published: May 2008

Farmers want a monitoring system to support decisions for plant cultivation and to obtain information for plant health conditions. This study established the remote monitoring system in a greenhouse and provided the machine vision system with remote control camera to extract plant images, to analyze a trend of lettuce growth, and to predict fresh weights of lettuce plants. The calibration bars with color patches were used for the geometric calibration and the extraction of lettuce regions from the image captured under sunlight conditions. The fresh weight prediction model was developed by the image analysis of lettuces growing in a greenhouse.
FORK BLADE-TYPE FIELD VELOCITY PROBE FOR MEASURING SHEAR WAVES
Authors: YOON HYUNG-KOO , LEE JONG-SUB , KIM YOUNG-UK , YOON SUNGSOO
Published: May 2008

The reasonable assessment of the shear wave velocity of soft soils in the laboratory is difficult due to the soil disturbance. This study presents a new apparatus, the blade-type field velocity probe, FVP, which overcomes several limitations of commonly used shear wave measurement methods in the field. The shear wave velocity of the FVP is simply calculated by using the travel distance and the travel time without inversion process. The FVP are carried out in clay soils up to 30m in depth. In addition, the dissipation of excess pore water pressure is investigated. The shear wave velocity is measured every 10cm. The velocity profiles with depth show the consolidation of the upper part of the soft clay. The shear wave velocity approaches asymptotic value after 50 minutes later due to the dissipation of excess pore water pressure. This study suggests that the blade-type FVP may be an effective device for measuring the shear wave velocity with minimized soil disturbance in the field.
ULTRASONIC DETERMINATION OF TEMPERATURE DISTRIBUTION IN THICK PLATES DURING SINGLE SIDED HEATING
Authors: TAKAHASHI MANABU , IHARA IKUO
Published: May 2008

A new ultrasonic method for determining temperature distribution of a thick plate being heated is presented. The principle of the method is based on temperature dependence of ultrasound velocity in heated materials. An inverse analysis method coupled with a finite difference calculation has been developed to determine one-dimensional temperature distribution in the heated plate. To demonstrate the feasibility of the developed method, a single side of a steel plate of 30 mm thickness is heated by contact with molten aluminum at 700°C and ultrasonic pulse-echo measurements are then performed for the steel during heating. The transit time of ultrasound of the heated steel is acquired and used to determine the transient variation of temperature distribution of the steel. The ultrasonically determined results almost agree with those measured using thermocouples installed in the steel.
IN SITU MONITORING OF PLASMA SPRAYING PROCESS BY LASER ACOUSTIC EMISSION METHOD
Authors: ITO KAITA , ENOKI MANABU , WATANABE MAKOTO , KURODA SEIJI
Published: May 2008

Estimation of microfractures in ceramic coating layer during plasma spraying process is critical for its reliability. Acoustic emission (AE) method enables in-process monitoring of such microfractures. Laser AE method was adopted to realize the monitoring of plasma spraying process by non-contact detection of AE with laser interferometer. Also a high performance method for noise reduction of laser AE waveform was investigated. In this new method, laser AE signal was continuously sampled and transformed into spectrogram by time-frequency analysis to cut out noise component effectively. After this noise reduction process, inverse transform was applied to obtain a clear AE signals in time domain. Whole these processes can be done in real time. The effectiveness of this method was confirmed by a detection test of simulated AE and successfully applied to the monitoring of plasma spraying process. Two types of AE events with different duration time range were found and the sources of these AE were presumed.
EVALUATION OF SUB-SURFACE MATERIAL PROPERTIES USING MINIMUM REFLECTION PROFILES METHOD
Authors: KIM DONG-YEOL , KIM HAK-JOON , SONG SUNG-JIN , KWON SUNG D.
Published: May 2008

Backscattered Rayleigh waves from the surface and/or sub-surface of specimens can be changed by scatterers such as micro-cracks, grain boundaries and surface roughness as well as by variations in material properties. In fact, rough surface generates higher energy of backscattered Rayleigh wave than smooth one. So, it is strongly needed to have a quantitative method to evaluate the variation of material properties only. To address such a need, we propose a new method, named as "minimum reflection profile" which measures energy variation of reflected waves from the surface of specimens as changing the angle of incident wave from normal to beyond Rayleigh angle in a pitch-catch immersion setup. Because of minimum reflection profile is less sensitive to roughness of surface than backward radiation profile. Also, we explore performance of the minimum reflection profiles by evaluating the sub-surface material properties of well known materials with various material properties.
USING SHORT-PULSE GROUND PENETRATION RADAR TO INVESTIGATE THE CONCRETE DETERIORATION AFTER HIGH-TEMPERATURE EXPOSURE
Authors: CHENG CHIA-CHI
Published: May 2008

The aim of this study is to develop a technique using short wave GPR to investigate damage of concrete after exposing to high-temperature. Specimens with various water to cement ratios were heated in electric oven for two hours. The specimens were evaluated by short-pulse GPR. In the GPR test, the signals corresponding to the reflections from the concrete surface transmitted by an antenna 300 mm above were used for analysis. The area enveloped by the response reflected from the concrete surface in time domain was calculated. The attenuation index (AI), with dB as the unit, was obtained from the enveloped areas after and before high-temperature exposure. The AI was compared to the Elastic Modulus of concrete near damaged surface obtained from drilling core. Results show AI can be used as the indicators on estimating the concrete having literally no damage (temperature below 300°C), minor damages (between 400 and 600°C), or major damages (above 800°C). Linear relation was found between AI and Elastic Modulus on the concrete surface.
EVALUATING BOND QUALITY AT STEEL/CONCRETE INTERFACES USING THE NORMALIZED IMPACT-ECHO SPECTRUM
Authors: LIN YICHING , HSU KENG-TSANG , CHENG CHIA-CHI
Published: May 2008

The objective of this paper is to develop a nondestructive test technique based on stress wave propagation for evaluating the bond quality of concrete structures strengthened by externally bonded steel plates. In this paper, a newly developed technique based on the normalized impact-echo spectrum was used to quantitatively detect the size of air voids at the interfacial epoxy layer between steel plate and concrete. Experimental results show that in the normalized impact-echo spectra, the amplitude of the peak at the frequency corresponding to the wave reflections at the steel/epoxy interface increases with an increase in the air void size. The bond strength decreases with an increase in the peak amplitude due to the increasing size of the flaw.
EVALUATION OF RESIDUAL STRESS OF COPPER PIPE BY USING RAMAN SPECTROSCOPY
Authors: KIM SANG-YOUNG , KOO JAE-MEAN , SEOK CHANG-SUNG
Published: May 2008

In most cases, a straight pipe is used after complicated bending work in a mechanical system. In this work process, the plastic deformation of the pipe produces residual stress in the pipe. This residual stress significantly affects the behavior of pipe fracture. For this reason, residual stress must be evaluated. Measuring the residual stress of a U-shaped copper pipe is difficult with existing destructive and nondestructive measurement methods. In this paper, the residual stress of a U-shaped copper pipe (99.9% pure copper) was evaluated from the Raman shift by Raman spectroscopy and FEM analysis. Also, the results of the bending test by FEM analysis and experiments are compared. The analyzed results of Raman spectra had a similar tendency with the results of the FEM analysis in regard to the residual stress distributions in the U-shaped pipes. Also, the results of the bending tests were shown resemblance.
STRESS CORROSION CRACKING RESISTANCE OF CF8A STEEL USED IN THE NUCLEAR POWER PLANT
Authors: BAE DONG HO , LEE GYU YOUNG , PARK KWANG JIN , PARK SUN KYU
Published: May 2008

In this investigation, stress corrosion cracking characteristics due to pipe material degradation in the primary stage environment of the nuclear power plant was evaluated. Firstly, after artificially degrading the CF8A steel during 2, 4, and 6 months at elevated temperature, 400°C, assessed the corrosion susceptibility of the degraded material following ASTM G5 standard. And next, stress corrosion cracking (S.C.C.) tests using smooth specimens fabricated with degraded material were conducted in the 2wt.% H 2 BO 3+ Li 7 OH solution at 60°C, and static stress of 0.8 σ y (σ y : yield strength of artificially degraded material). From the results, corrosion rates linearly increased with increasing of degradation period and solution temperature. And both the raw material and the degraded materials were not failed during the S.C.C. test period. In spite of long time test (about 3,900 hrs) under S.C.C. test condition, surface pits or surface corrosion by the electro chemical reaction were not observed. Consequently, CF8A steel using as one of the pipe material in the primary stage of the nuclear power plant showed good S.C.C. resistance in 2wt.% H 2 BO 3+ Li 7 OH solution.
PERFORMANCE OF A CDTE-BASED DIGITAL GAMMA IMAGING SYSTEM WITH A 75SE RADIOISOTOPE FOR NONDESTRUCTIVE TESTINGS
Authors: CHO H. S. , CHOI S. I. , KIM K. Y. , OH J. E. , LEE S. Y. , LEE B. S. , KIM S.
Published: May 2008

As a continuation of our digital radiographic sensor R&D, we have developed a digital gamma imaging system based upon the cadmium-telluride ( CdTe ) photoconductor for the applications of industrial gamma imaging. The imaging system consists of a commercially-available CMOS pixel array of a 100 × 100 μ m 2 pixel size and a 5.4 % 151.0 mm 2 active area, coupled with a 750-μm-thick CdTe photoconductor, and a collimated selenium (75 Se ) radioisotope of an about 62.8 Ci activity and a physical size of 3.0 mm in diameter. In this study, we, for the first time, succeeded in obtaining useful gamma images of several test phantoms with the 75 Se radioisotope from the imaging system and evaluated its imaging performance in terms of the modulation transfer function (MTF), the noise power spectrum (NPS), and the detective quantum efficiency (DQE). For comparison, we also tested its X-ray imaging performance with a microfocus X-ray tube of an about 5 μm focal spot size at an operation condition of 90 kVp and 100 μA.
LASER ULTRASONIC INSPECTION SYSTEM WITH A 3D SURFACE PROFILOMETRY TO DETECT SURFACE CRACKS
Authors: PARK SEUNG-KYU , BAIK SUNG-HOON , CHA HYUNG-KI , CHEONG YONG-MOO , KIM WOON-IL , CHO CHANG-HO , KANG YOUNG-JUNE
Published: May 2008

We have developed a nondestructive surface-crack detection system by using laser ultrasound and optical 3D surface profilometry. The system can robustly acquire crack information by using the laser ultrasonic analysis data with visual surface profiling data where both data are produced by the same line-shaped pulse laser beam. By the help of the visual 3D shape data for a surface crack, this ultrasonic inspection system can provide reliable surface crack information. In this paper, the hardware configuration of the combined nondestructive laser inspection system to detect surface cracks will be described. Also, the experimental results to detect multi surface cracks by using the developed system will be presented.
OPTIMIZED DESIGN PARAMETERS OF EDDY CURRENT BOBBIN PROBE FOR STEAM GENERATOR TUBE IN NPPS
Authors: LEE HEE JONG , NAM MIN WOO , CHO CHAN HEE , JEE DONG HYUN
Published: May 2008

The bobbin probe is now widely accepted as a basic and important ECT technique among various ECT techniques for steam generator tube integrity assessment that is practiced during each plant outage. The bobbin probe is also one of the essential components which consist of the whole ECT examination system, and provides us with decisive data for the evaluation of tube integrity in accordance with acceptance criteria described in specific procedures. Accordingly, the design of ECT probe is especially important to examination results because the quality of acquired ECT data is determined by the optimized probe design characteristics, such as coil geometry, electrical properties, operation frequency, and so on. In this study, the relationship between electric characteristic changes and differential coil gap variation for the optimization of the ECT probe signal was investigated. As a result, for the examination of volumetric flaws fabricated on the O.D. side of ASME type calibration standard, we propose that the best Lissajous signal for the examination will be obtained when the coil gap of differential bobbin probe is approximately 1.2 ~ 1.6 mm .
IRRADIATION INDUCED DEFECT CHARACTERIZATION IN REACTOR PRESSURE VESSEL STEEL BY SMALL ANGLE NEUTRON SCATTERING
Authors: HAN YOUGN-SOO , SHIN EUN-JOO , LEE CHANG-HEE , PARK DUCK-GUN
Published: May 2008

The degradation of the mechanical properties of the RPV (Reactor Pressure Vessel) steel during an irradiation in a nuclear power plant is closely related to the irradiation induced defects. The size of these defects is known to be a few nanometer, and the small angle neutron scattering technique is regarded as the best non destructive technique to characterize the nano sized inhomogeneities in bulk samples. The investigated the RPV steel has been used in YeongKwang nuclear power plant at Korea and the Cu content of the RPV steel is 0.06 wt%. The RPV steel was irradiated in the HANARO reactor at KAERI. The small angle neutron scattering experiments were performed by the SANS instrument in the HANARO reactor. The nano sized irradiation induced defects were quantitatively analyzed by SANS and the type of the irradiation induced defects was discussed in detail. The relation between irradiation induced defects and the yield strength was investigated. The characteristics of irradiation induced defects in low Cu containing RPV steel were discussed.
METALLIC CONTAMINANT DETECTION SYSTEM FOR INDUSTRIAL PRODUCTS BY HIGH TC SQUID MAGNETIC SENSOR
Authors: TANAKA SABURO , FUJITA HIROYOSHI , HATSUKADE YOSHIMI , OTANI TAKEYOSHI , SUZUKI SHUICHI
Published: May 2008

High-Tc superconducting quantum interference device (SQUID) system for detection of magnetic foreign matter in industrial products was developed. There is a possibility that ultra-small metallic foreign matter has been accidentally mixed with industrial products, such as lithium ion batteries. The outer dimension of metallic particles less than 100 microns cannot be detected by conventional X-ray imaging. Therefore, we developed a detection system based on high-Tc SQUID microscopes with a high-performance magnetic shield. Using SQUID microscopes with a 0.5 mm-thick vacuum window was proposed. This design enables the SQUID to approach an object to be measured as close as 1 mm and enhances the sensitivity. A new magnetic shield with sleeves was carefully designed and built. As a result, we could successfully measure a small iron particle with 100 μm. This detection level was hard to achieve by conventional X-ray detection methods.
OPTIMAL DESIGN OF A 1-3 PIEZOCOMPOSITE TONPILZ TRANSDUCER BY MEANS OF THE FINITE ELEMENT METHOD
Authors: PEI DA LIE , ROH YONGRAE
Published: May 2008

Underwater Tonpilz transducer is designed with 1-3 piezocomposite materials to overcome the problems with conventional piezoceramic transducers. With the FEM, the variation of the resonance frequency, bandwidth and sound pressure of the transducer are analyzed in relation to the structural variables of the transducer. Through statistical multiple regression analysis of the results, functional forms of the transducer performance are derived in terms of design variables. By applying the constrained optimization technique, SQP-PD, to the derived functions, the optimal structure of the transducer is determined that can provide the highest sound pressure level at a given resonant frequency over a pre-determined frequency range. The validity of the optimized results is confirmed through comparison of the optimal performance with that of the FEA.
TUNING FORK HORN DESIGN FOR ULTRASOUND EXCITATION THERMORAPHY
Authors: CHOI MANYONG , KWON HYU-SANG , KANG KISOO
Published: May 2008

In ultrasound excitation thermography, the injected ultrasound to an object is transformed to heat by thermo-structure effect and internal friction. The advantage of this technique is selectively sensitive to thermally active defects. The appearance of defects, which can be visualized by thermography camera, depends strongly on the method of excitation. In preliminary studies, ultrasonic excitation horns of ultrasonic manufacturing process are widely adopted for a polymer structure. However, it is needed that these horns are modified for improving the defect detection capability. This paper proposes a new ultrasonic excitation horns with tuning fork shape in NDT of polymer material. Geometric conditions are optimized by FEA and application results by the developed horn are described and compared with those by a previous horn.
DEVELOPMENT OF BIOLOGICAL ACOUSTIC IMPEDANCE MICROSCOPE AND ITS ERROR ESTIMATION
Authors: HOZUMI NAOHIRO , NAKANO AIKO , TERAUCHI SATOSHI , NAGAO MASAYUKI , YOSHIDA SACHIKO , KOBAYASHI KAZUTO , YAMAMOTO SEIJI , SAIJO YOSHIFUMI
Published: May 2008

This report deals with the scanning acoustic microscope for imaging cross sectional acoustic impedance of biological soft tissues. A focused acoustic beam was transmitted to the tissue object mounted on the "rear surface" of plastic substrate. A cerebellum tissue of rat and a reference material were observed at the same time under the same condition. As the incidence is not vertical, not only longitudinal wave but also transversal wave is generated in the substrate. The error in acoustic impedance assuming vertical incidence was estimated. It was proved that the error can precisely be compensated, if the beam pattern and acoustic parameters of coupling medium and substrate had been known.
AN ENHANCED REFLECTION REMOVAL TECHNIQUE AND ITS APPLICATIONS
Authors: KWON HYU-SANG , CHOI YOUNG-CHUL , PARK JIN-HO , YOON DOO-BYUNG
Published: May 2008

Electroacoustic transducers using piezoelectric materials are popular in various applications such as underwater acoustics, ultrasound, earthquakes and elastic wave propagations. Especially, they are widely used in non-destructive testing for ultrasonic or acoustic emission transducers. In general, they generate and receive waves through media to find meaningful targets or physical characteristics of materials. However, in most uses, the media are bounded with finite dimensions, therefore there are multiple transmitting paths reflected from the boundaries. Such reflections corrupt the principal path signal to be analyzed. To overcome this problem, gating technique to gate successively transmitting and receiving signals, in other words, tone-burst signal technique, is most representatively used. This basically isolates the direct signal before the arrival of reflected signals in the time domain, and therefore it is also described as time windowing or time-selective windowing techniques without loss of generality. These techniques have inherent overlap problems invoked by long pulse duration, especially slightly damped signals or low frequency waves. An enhancement technique of shortening the pulses by digital filtering is proposed and successively applied in practical uses. It can isolate the principal path signal from reflected signals. Thereafter the signal can be perfectly recovered after removing reflections.
SECURITY ANALYSIS OF AES USING FUNCTIONALITY FAULT MODEL
Authors: FAURAX OLIVIER , MUNTEAN TRAIAN
Published: May 2008

Security of cryptographic circuits is a major concern. Smartcards are targeted by sophisticated attacks like fault attacks that combine physical disturbance and cryptanalysis. We propose a methodology and a tool (PAFI) to analyze the robustness of circuits under fault attacks using fault injection in simulation. The number of injections is reduced by taking into account the function of the latches in the whole circuit. We tested a circuit implementing the cryptosystem AES and showed that our approach reduces the number of fault injections to be performed (- 80%). Moreover, most of the selected injection points are the ones that lead to known fault attacks (95%).
SYNTHESIS OF PROPERTY MONITORS FOR ONLINE FAULT DETECTION
Authors: MORIN-ALLORY K. , GASCARD E. , BORRIONE D.
Published: May 2008

An original method for generating components that capture the occurrence of events is proposed, and logical and temporal properties of hardware/software embedded systems are monitored. The properties are written in PSL, under the form of assertions in declarative form. The method includes the construction of a library of primitive digital components for the PSL temporal and sequence operators. These building blocks are interconnected to construct complex properties, resulting in a synthesizable digital module that can be properly linked to the digital system under scrutiny.