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This study aimed to investigate the effect of suppressing transpiration on the physiological characteristics of trees and identify suitable indicators to assess tree vitality. Three seedlings of Zelkova serrata were used: a control, a unit treated on the upper sides of the leaves (TU), and a unit treated on double sides of the leaves (TD). Changes in photosynthetic rate, transpiration rate, sap velocity, and bark temperature following the suppression of transpiration were measured. The transpiration rate and other physiological characteristics of TU were not significantly different from those of the control except for photosynthetic rate. However, TD showed a significantly lower photosynthetic rate, transpiration rate, and sap velocity compared to the control. The bark temperature of TD was not significantly higher than that of the control and TU. Our findings indicate that photosynthetic rate and sap velocity were positively correlated with transpiration rate, whereas bark temperature was negatively correlated. Furthermore, photosynthetic rate showed the most significant linear relationship with transpiration rate, suggesting the photosynthetic rate is a suitable physiological indicator to evaluate the vitality of Z. serrata.

This paper develops a methodology to predict the End-Of-Life (EOL) fundamental frequency of a Pressurized Water Reactor (PWR) fuel assembly using lateral bending test data. Bending energy, developed from the lateral bending tests, is utilized to predict the first mode natural frequency. It is shown that the estimation provides reasonable results when the deflected shape is close to the first mode shape. One can evaluate the structural integrity against earthquakes by utilizing a simulation tool that uses the physical information of the fuel assembly. One of the important pieces of information for the simulation is the first natural frequency of the fuel assembly, because the dominant frequency components of the reactor motion are close to the fundamental frequency of the fuel assembly. When the EOL information is unavailable, the unknown EOL fundamental frequency can be identified directly through tests. However, it is almost impossible to build a specific fuel assembly when the fuel assembly is no longer produced. Therefore, this paper suggests using the load-to-deflection curve from the static bending test to predict the fundamental frequency of the EOL fuel assembly. Estimation errors are also discussed, and it is shown that the errors can be minimized using the bending energy considering the deflected bending shape that is the most similar to the fundamental mode shape. Two test examples are discussed, and the results show that the suggested method provides reliable results.

Blockchain is the most popular security network technology in the 21st century and still under active research. The consensus algorithms in Blockchain plays a major role and are crucial for maintaining the integrity and security of a distributed network. In addition, there are various problems arising from the consensus algorithms adopted in the existing Blockchain network. Therefore, it is of upmost importance to develop a consensus algorithm to address these problems. In this paper, therefore, we propose an efficient consensus algorithm in a Blockchain network environment consisting of several distributed users. First, we study the process of consensus among users to add new blocks to the existing Blockchain. Second, we introduce the other conventional consensus algorithms, analyze the problems of each algorithm, and propose Rock-Scissors-Paper (RSP) algorithm to mitigate these problems. The RSP algorithm is an algorithm that achieves consensus among distributed users using three static balanced variables, Rock (R), Scissors (S), and Paper (P) to avoid attacks by malicious participants. Furthermore, the propose RSP algorithm is compared with the existing consensus algorithms to predict the performance and its effects in a distributed mobile network environment.

We studied the electrical, optical and valley properties of monolayer MoSe2. The measured PL circular polarization of monolayer MoSe2 was negligibly small, compared with the more-than 60% circular polarization of monolayer MoS2. Doping-dependent PL measurement and Kelvin probe microscopy show that the small circular polarization because of its longer exciton lifetime in monolayer MoSe2. Furthermore, it is found that the longer exciton lifetime is due to the nearly intrinsic electrical property of monolayer MoSe2, where non-radiative trion decay, which is the dominant exciton decay mechanism in n-type monolayer MoS2, is minimized due to the low density of excess electrons (holes). We believe that S and Se vacancies play an important role in determining the Fermi level position for these materials. Our experimental results show that monolayer MoSe2 can be a better valleytronics material than monolayer MoS2 in spite of its small circular polarization.

The revised U.S. Nuclear Regulatory Commission(NRC), Regulatory Guide(RG) 1.20, rev.3 requires the evaluation of the potential adverse effects from pressure fluctuations and vibrations on piping and components for the reactor coolant, steam, feedwater, and condensate systems. Detailed vibration analyses for the systems attached to the steam generator are very difficult, because these piping systems are very complicated. This paper suggests a screening method for the flow-induced vibration of acoustic resonances and pump-induced vibration of the piping systems attached to the steam generator in order to conduct the APR1400 comprehensive vibration assessment program. This paper seeks to address the areas such as potential vibration sources, and methods to prevent the occurrence of acoustic resonances and pump-induced vibration of piping systems attached to the steam generator, for conducting the APR1400 comprehensive vibration assessment program. The screening method in this paper will be used to estimate the flow-induced vibration of the piping systems attached to the steam generator for the APR1400.

We study the effects of charged defects and impurities on the optical properties and the valley polarization in monolayer MoS2. Both the defects generated by vacuum annealing and the impurities introduced by AuCl3 chemical doping dramatically increase the photoluminescence (PL) intensity. This is due to a p-doping effect, which increases the exciton lifetime by suppressing the non-radiative trionic decay in the n-type, as-exfoliated monolayer MoS2. The PL from vacuum-annealed MoS2 can be controlled reversibly. It decreases upon laser irradiation or pumping in a vacuum due to the desorption of air molecules adsorbed at S-vacancy sites and recovers slowly with the re-adsorption of air molecules. Both the vacuum annealing and the AuCl3 doping reduce the valley polarization significantly. A systematic study on the PL and the circular polarization reveals that the reduction in the circular polarization cannot be explained by the increased exciton lifetime alone. The valley polarization almost recovers to its pre-annealing value after pumping in a vacuum, indicating that S-vacancies with ‘charged’ air molecules affect the valley properties more strongly than neutral ones. The valley polarization decrease is more significant at high temperatures, which excludes the increased intervalley scattering due to defects or impurities as its main origin. Relaxation of the valley-contrasting optical selection rule due to defects or impurities, which was reported recently, seems to explain our experimental results better.

In this study, we investigated the effects of a crosslinking agent and a compatibilizer on the mechanical and rheological properties of waste PP and waste ground rubber tire (WGRT) composites. In order to simulate a commercial TPV, the component of waste PP and WGRT was fixed at 30 and 70 wt%, respectively. With the simple addition of SEBS-g- MA into the waste PP/WGRT composites, the tensile strength of the composite was decreased, whereas both the elongation at break and impact strength were significantly increased because of rubbery characteristics of SEBS-g-MA. In order to further improve the properties of the composites, the waste PP/WGRT/SEBS-g-MA composites was revulcanized with dicumyl peroxide (DCP). As expected, mechanical properties of the revulcanized composites was generally improved. Especially, with 15 and 1 phr of SEBS-g-MA and DCP, elongation at break was highest value of about 183% because of the recrosslinking of WGRT without chain scission of the main chain. It was found that complex viscosity of the revulcanized composite increased which might verify further vulcanization of the WGRT.

We show that optical second-harmonic generation (SHG) from few-layer MoSe2 can sensitively probe external symmetry perturbations such as chemical doping. The SHGs from few-layer MoSe2 are enhanced after AuCl3 chemical doping, especially more so for the thicker MoSe2 samples. This enhancement is due to an electric-field-induced SHG contribution originating from the charge transfer between the adsorbed chemical dopants and the MoSe2. By using this sensitivity, we demonstrate an in-situ monitoring of the thermal desorption of adsorbed chemical dopants. Moreover, we find that the SHG generated from monolayer MoSe2 is counter-circularly polarized for a circularlypolarized fundamental beam due to the three-fold rotational symmetry of MoSe2. Our work shows that SHG can probe not only the symmetry properties of atomically-thin 2D semiconductors, but also the external symmetry perturbations on them.

We study the excitonic valley polarization and coherence in few-layer MoS2 by using circular- and linear-polarization-resolved photoluminescence. The valley polarization is largest in monolayer MoS2 and decreases with increasing number of layers or temperature. Contrary to the valley polarization, the linear polarization is negligibly small in monolayer MoS2 and increases with increasing number of layers or temperature. The temperature-dependent valley depolarization can be explained by the exciton center-of-mass momentum-dependent electron-hole exchange interaction. The valley decoherence in few-layer MoS2 is much faster than the valley depolarization at low temperature and is steady against increasing temperature or photoexcitation intensity, indicating that the decoherence process does not involve phonon or carrier-carrier scattering. The dominant valley decoherence has a pure dephasing origin and cannot be explained by the valley-depolarizing e-h exchange interaction.

Named data networking (NDN) is a novel communication paradigm that employs names rather than references to the location of the content. It exploits in-network caching among different nodes in a network to provide the fast delivery of content. Thus, it reduces the backhaul traffic on the original producer and also eliminates the need for a stable connection between the source (consumer) and destination (producer). However, a bottleneck or congestion may still occur in very crowded areas, such as shopping malls, concerts, or stadiums, where thousands of users are requesting information from a device that resides at the edge of the network. This paper provides an analysis of content delivery in terms of the interest satisfaction rate (ISR) in ultra-dense network traffic situations and presents a final and an adequate statistical model based on multiple linear regression (MLR) to enhance ISR. A four-way factorial design was used to generate the dataset by performing simulations in ndnSIM. The results show that there is no significant interaction between four predictors: number of nodes (NN), number of interests (NI) per second, router bandwidth (RB), and router delay (RD). Moreover, the NI has a negative effect, and log(RB) has a positive effect on the ISR. The NN less than 10 has a significantly higher effect on the ISR compared with other nodes&rsquo, densities.

We investigated the coherent acoustic and optical phonon dynamics in a Ge2Sb2Te5 phase change material by using pump-probe spectroscopy. Oscillating reflectivity changes with oscillation period and de-phasing time on a timescale of tens of picoseconds were observed and could be consistently explained by coherent acoustic phonon generation in the form of a strain pulse propagating into substrate. The temperature-dependent frequency shift of the coherent optical A1 phonon mode was due to a three-phonon anharmonic decay while its de-phasing was dominated by temperatureindependent phonon-vacancy scattering at low temperature. A laser-fluence-dependent A1 phonon mode softening and a dephasing rate increase were observed and attributed to the high density of electrons and the accompanying lattice distortion, as well as the increase in the lattice temperature.

Highly-strained BiFeO3 (BFO) thin films have been found to exhibit a ‘tetragonal-like monoclinic’ crystal structure different from the bulk rhombohedral structure. Here, we report our second harmonic generation (SHG) study of epitaxially-strained tetragonal-like (T-like) BiFeO3 films as a function of temperature and film thickness. We observed a strong SHG peak at ∼370 K, corresponding to a structural phase transition between two T-like BFO phases. Our SHG symmetry analysis revealed that a non-tetragonal intermediate phase that appeared at the structural transition was responsible for the enhanced SHG. We also observed a noticeable enhancement and symmetry change of SHG at the G-type-to-C-type anti-ferromagnetic transition, suggesting the possibility of a structural change coupled to the magnetic transition.

Dynamic rheological properties of PP-based long glass fiber-reinforced thermoplastics (LFT) were investigated. Weight fractions of the glass fibers investigated in the present study ranged from 0.15 to 0.5, which are higher than those of previous studies. We observed very abnormal rheological behavior. Complex viscosity (η*) of the LFT increased with the glass fiber content up to 40 wt. %. However, the η* with a weight fraction of 0.5 is observed to be lower than that of LFT with a weight fraction of 0.4 in spite of higher glass fiber content. From various experiments, we found that this abnormal behavior is analogous to the rheological behavior of a lyotropic liquid crystalline polymer solution and concluded that the abnormal rheological behavior for the LFT is attributed to the formation of a liquid crystal- like structure at high concentrations of long glass fibers.

To investigate the effect of long chain branching (LCB) on melt fractures of metallocene-catalyzed linear low-density polyethylene (mLLDPE), we prepared a series of sparsely long-chain-branched mLLDPEs with well-defined degrees of LCB. Gross melt fractures were observed to decrease as the degree of LCB increases. This is in accordance with a prediction based on the observation that LCB enhances chain entanglement and consequently increases the melt strength of a polymer. However, sharkskin melt fracture (SMF) was observed to be more severe with the degree of LCB. There have been debates over the effect of LCB on SMF. According to a well-known mechanism of SMF, SMF is expected to decrease with the degree of LCB. Therefore, the majority of research groups believe that SMF decreases with the degree of LCB. This study clearly shows that the SMF becomes more severe with an increase of the degree of LCB and suggests another possible mechanism for the SMF. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

In this study, flow characteristics in a multi-cavity injection molding process were investigated. One of main problems occurred in the multi-cavity molding is a flow imbalance among cavities since it affects physical properties and quality of products. Charge imbalance is caused by the uneven shear stress. Therefore, changes in viscosity affect the physical properties of resin and injection conditions differ in the filling imbalance phenomenon. Through, this study focus on experimental studies of flow imbalance for PC and PP resin occurring in a balanced delivery system. Experimental results were compared with CAE results. By experimental and CAE analysis, main cause for the flow imbalance is temperature distribution in cross section of runner. New runner system with a simple change of runner shape was suggested to avoid the flow imbalance. A series of simulation to confirm feasibility of Volume Runner`s effects was conducted using injection molding CAE.

This research aims to develop polymer composites which can be used for PEMFC bipolar plate by injection molding process. Considering the moldability and stiffness, we used LCP(Liquid crystal polymer) as base resin. In order to improve electrical conductivity and mechanical properties, we chose carbon black, and both synthetic graphite and expanded graphite. The composites with different recipe are prepared for injection molding of PEMFC bipolar plate and CAE(Computer Aided Engineering) analysis was performed to predict melt flow and fiber orientation We did successfully fabricate the ASTM specimens by injection molding, and measure the electrical conductivity of the samples by using four point probe device. We measured mechanical properties such as flexural strength, flexural modulus and Izod impact strength. Conclusively, the electrical conductivity increased with increasing additive concentration, but both flexural strength and Izod impact strength decreased due to the brittle nature of carbon-based additives.

ZnO doped with non-magnetic C has been reported to exhibit room-temperature ferromagnetism (RTF). The theoretical explanations of the RTF in ZnO:C are based on the incorporation of C at the O site and on the p-p exchange interaction between the localized C2p spins and valenceband holes. Here, we investigated the incorporation site of C and the electrical properties of Cdoped ZnO films grown by using pulsed laser deposition (PLD) under oxygen-rich and oxygen-poor conditions. Contrary to the theoretical explanations, all the C-doped ZnO films exhibited n-type conductivity. Furthermore, most of the carbons were not incorporated at the O site, but rather at the interstitial or Zn site, or formed C clusters. Although there may exist a growth method that can lead to incorporation of C at the O site, our experimental results indicate that the defect-induced ferromagnetism mechanism can better explain most of the observed RTF in the PLD-grown ZnO:C films.

This research aims to develop polymer composites which can be used for PEMFC separators by injection molding process. Considering the moldability and stiffness, we used PPS(Poly(phenylene sulfide)) and PP(Polypropylene) as base resin. In order to improve electrical conductivity and physical properties, we chose glass fiber, carbon fiber, carbon black, and both expanded graphite and synthetic graphite. The 3 type composites are prepared for injection molding of PEMFC separators. and CAE(Computer Aided Engineering) analysis was conducted to optimize injection processing parameters(injection pressure, heat time, mold temperature etc.). We did successfully fabricate the separators by injection molding, and measure the electrical conductivity of the samples by using four point probe device. Conclusively, PP/SG/CB composite showed better both electrical conductivity and moldability than the others. Key Words : PEMFC, Separator, Injection Molding, Compression Injection Molding, E-MOLD, CAE Analysis

Capillary extrusion experiments involving a number of polyethylenes with emphasis on assessing the effect of long chain branching (LCB) are performed. None of the metallocene catalyzed linear low density polyethylenes (mLLDPE) produced by Dow Chemicals, which are believed to have some level of LCB, show temperature dependence on the viscosity at the gross melt fracture regime. Furthermore, these materials do not show spurt or stick-slip flow, in contrast with most linear polyethylenes. LDPE and blends of LDPE with LLDPE having LCB also show the absence of stick-slip flow, but show temperature dependence on the viscosity. From these observations, we conclude that the stick-slip flow is very sensitive to the existence of LCB.

We studied the e ect of laser spike annealing (LSA) on the defects of hafniumoxide (HfO2) high-k dielectric stacks. We found that positive charge generation, extracted from C-V measurements was suppressed for laserspikeannealed HfO2 gate stacks compared with conventional rapidthermallyannealed (RTA) gate stacks. It seems that LSA suppresses the growth of under-oxidized interfacial oxide layer by minimizing oxygen di usion, resulting in less positive charge generation. C-V hysteresis and defect photoluminescence, however, showed enhanced charge trapping and increased oxide defect density for the laser spike annealed HfO2 gate stacks. High-density non-equilibrium chargetrapping defects seem to be created in the HfO2 layer during the rapid cooling process of LSA. We performed post-LSA, lowthermalbudget annealings in various ambient gases to quench or passivate chargetrapping defects, but they didn't seem to e ectively deactivate the LSAcreated oxide defects.

In this paper, we adopted E-MOLD patent technology in order to fabricate Prismless LGP(Light Guide Panel) fur cellular phone and estimate the transcription of injection-molded parts. Then, we manufactured the Ni stamper fur Prismless LGP using MEMS process. And the stamper was installed in the movable heated core which is the key part of a patented mold. Using this mold, we manufactured injection-molded plastic LGP parts with different mold temperatures so that we investigate effect of the temperature on the transcription of the parts. The CAE analysis was also conducted in order to compare with the experimental results. The transcription of LGP parts with various mold temperature displayed (25.0nm), (48.4nm), (52.1nm) and when compared with stamper(521Inm), transcription was superior at . According to the CAE results, moldability was improved as mold temperature () increased, but when filling time() increases, it decreased at . And transcription and moldability were improved markedly at glass transition temperature().

This study examined the electrochemical deposition and dissolution of lithium on nickel electrodes in a propylene carbonate (PC) electrolyte containing different LiN(SO2C2F5)2 concentrations. The electrolyte concentration was found to have a significant effect on the reactions occurring at the electrode. The poor cycleability of the electrodes in the low-concentration solutions was improved considerably by increasing the electrolyte concentration. Transmission electron microscopy (TEM) revealed that a high-concentration solution produces a thinner solid electrolyte interphase (SEI) on the electrodeposited lithium than a low-concentration solution, e.g., ∼35 nm in 1.28 mol kg−1 vs. ∼20 nm in 3.27 mol kg−1 solutions. Raman spectroscopy showed that the solvation number of lithium ions differed according to the electrolyte concentration. This suggests that the structure of solvated lithium ions is an important factor in suppressing dendritic lithium formation. Keywords: Lithium battery, Dendritic lithium, SEI, TEM, Solvated lithium ion, Solvation number, Cycling efficiency

Abnormal rheological behavior is observed during capillary extrusion with a linear low density polyethylene (LLDPE). The nominal viscosity in the stick-slip flow regime and the gross melt fracture regime increase with a rise in temperature. This is attributed to slippage of the polymer melts. It is generally accepted that the occurrence of slippage can be detected by a Mooney analysis. However, it is found that the Mooney analysis is not applicable to detect the occurrence of slippage in the gross melt fracture regime. This is attributed to the main assumptions in the Mooney analysis being invalid in this regime, mainly due to the presence of a turbulent-like flow pattern. We suggest that failure of the time-temperature superposition principle can be used as an indication of slippage for polymer melts.

We conducted and verified the structural safety analyses for a type B transport package for a radioactive waste drum. The type B package is used to transport one high-level radioactive waste drum from a waste facility to a temporary site in a nuclear power plant. It is important that the structural integrity of a type B transport package should be maintained under normal transport conditions such as the free drop test, the stacking test and the penetration test, and accident conditions of transport such as the 9 m height free drop test and the puncture test. Based on the ASME Boiler and Pressure Vessel Code, Section III, Division 3 we evaluated the structural safety integrity of the type B package for a radioactive waste drum using finite element analysis. For the stacking test condition the maximum stress is a very low value when compared with the stress limits. The impact of the penetration bar on the overpack does not affect the containment part. For the free drop test condition and the puncture test condition the local stresses appear at the impact part and the containment part connected with the inner structure. The maximum stresses for all of the conditions are lower than the stress limits, so the structural integrity of the type B package for a radioactive waste drum was maintained. Also, the structural safety analyses were verified by using the data acquired from the 9 m drop and the puncture tests of the real model. The analytic accelerations of the 9 m drop test are similar to the test results. For the puncture test condition the analytic result is conservative when compared to the test. The analysis for the structural safety of the type B package reveals conservative results and it is proved that its structural integrity is maintained under normal and accident conditions of transport.

A spent fuel storage cask is required to prove the safety of its canister under a hypothetical accidental drop condition which means that the canister is assumed to be free dropped on to a pad of the storage cask during the loading of the canister into a storage cask. In this paper, finite element analyses and verifying tests for a shock-absorbing effect of a pad in a spent fuel dry storage cask were carried out to improve the structural integrity of the canister under a hypothetical accidental drop condition. The pad of the storage cask was originally designed as cylindrical steel structure filled with concrete. The pad was modified by using the structure composed of steel and polyurethane-foam instead of the quarter of the upper concrete as an impact limiter. The effects of the shape and the thickness of the steel structure and the density of the polyurethane-foam which was used in between steel structures were studied. As the optimized pad of a spent fuel dry storage cask, the quarter of the upper concrete was replaced with 12 mm thick circular steel structure and polyurethane-foam whose density was 85 kg/m 3 . The drop tests of a 1/3 scale model for the canister on to the original pad and the optimized pad were conducted. The effect of the pad structure was evaluated from the drop tests. The optimized pad has a greater shock-absorbing effect than the original pad. In order to verify the analysis results, strains and accelerations in the time domain by the analytical methods were compared with those by a test. The numerical method of simulating the free drop test for a dry storage cask was verified and the numerical results were found to be reliable.