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A book-shaped all-in-one energy harvester module with a piezo-triboelectric hybrid structure as a next-generation eco-friendly energy source was manufactured based on flexible piezoceramic nanofibers with enhanced current characteristics obtained by controlling the added amount of carbon black (CB). To prepare flexible piezoceramic nanofibers with favorable current properties, 0.78Bi0.5Na0.5TiO3−0.22SrTiO3 (BNT-ST) piezoelectric ceramics were composited with CB, a highly conductive material, and then electrospun with a poly(vinylidene fluorideco–trifluoroethylene) polymer. The prepared CB/BNT-ST nanofibers were modularized into piezoelectric energy harvester modules (PEHMs) with interdigitated electrodes, yielding an improved output performance with a high voltage of 10.1 V and high current of 2.02 nA. A book-shaped triboelectric energy harvester module (TEHM) was manufactured with polydimethylsiloxane on one side and the CB/BNT-ST nanofibers on the other side, affording an improved output performance with a high voltage of 391 V and high current of 130 μA. A book-shaped all-in-one hybrid energy harvester module (HEHM) was then manufactured by fitting PEHMs at both ends of the book-shaped TEHMs. As a result of optimizing the output performance by connecting HEHM multiple layers, a high voltage and current of 1043 V and 579 μA were observed, respectively, and charging of a 1.0 μF capacitor was completed in 25 s. Furthermore, in simulated energy harvesting experiments using the all-in-one HEHM, LED light bulbs were clearly illuminated in real time, and an electronic calculator was operated without charging. This work suggests the application potential of the all-in-one HEHM as the next generation of eco-friendly flexible energy sources.

An all-in-one energy harvester module comprising a top piezoelectric layer, a bottom piezoelectric layer, and a middle triboelectric layer was fabricated based on flexible piezoceramic nanofibers to serve as a power source for wearable devices. The top and bottom piezoelectric layers were manufactured by modularizing electrospun piezoceramic nanofibers with an interdigitated electrode, and the energy harvesting characteristics were maximized by laminating the single modules in z-axis array arrangements. The triboelectric layer was manufactured by attaching polydimethylsiloxane on both sides of an electrode layer, and the energy harvesting characteristics were controlled according to the surface roughness of the triboelectric modules. The output voltages of the individual energy harvester modules of the all-in-one module were individually or integrally measured by hand pressing the lower and upper parts of the module. The all-in-one energy harvester module generated a maximum voltage (power) of 253 V (3.8 mW), and the time required to charge a 0.1 μF capacitor to 25 V was 40 s. The results of a simulated energy harvesting experiment conducted on the all-in-one energy harvester module showed that 42 LED bulbs arranged in the shape of the "KICET" logo could be turned on in real time without charging, and a mini fan consuming a power of 3.5 W was operated after charging a 10 μF capacitor for 250 s. This work shows the potential of the all-in-one module as an ecofriendly flexible energy harvester for operating wearable devices.

Highly porous-cellulose-acetate (CA) nanofibers were prepared by an electrospinning process based on a nonsolvent-induced phase separation (NIPS) mechanism, and their PM

Antiferromagnetic topological insulators have attracted great attention in the condensed matter physics owing to the fundamental interest in exotic quantum states and topological antiferromagnetic spintronics. Starting with the typical topological insulator of Bi2Te3, we introduced the magnetic order by substituting Gd at the Bi site and tuned the Fermi level by substituting Se at the Te site. That is, we prepared single crystals of Gd xBi2− xTe3− ySe y with various x (= 0.02 and 0.06) and y (= 0.1, 0.2, 0.5, 0.7, 1.0, and 1.5). The magnetic data revealed an antiferromagnetic order for x = 0.06, and the transport data manifested the charge neutral point at y = 0.7. Combining all these results together, the material with x = 0.06 and y = 0.7 is characterized as an antiferromagnetic topological insulator, where we observed exotic magnetotransport properties such as weak antilocalization and negative longitudinal magnetoresistance that are frequently analyzed as chiral anomalies in Weyl materials.

UV-curable different-colored 3Y-ZrO2 ceramic nanocomposite resins with a ceramic content of 50 vol% were prepared for supportless stereolithography 3D printing. Based on the correlation between the solubility parameters of UV-curable organic resin systems and the rheological behaviors of highly loaded ceramic nanocomposites, the physical properties of the different-colored 3Y-ZrO2 ceramic nanocomposite resins, such as photocurability, viscosity, flowability, and printability, were optimized for a supportless 3D printing process. Thus, white, pink, yellow, and gray 3Y-ZrO2 ceramic nanocomposite resins with optimum physical properties were prepared. The different-colored 3D-printed 3Y-ZrO2 objects sintered at 1450 °C for 180 min exhibited a high relative density of>99.90% and a high flexural strength of>930 MPa, which are comparable to those of commercial 3Y-ZrO2 manufactured by a conventional ceramic process. In addition, gear-shaped objects with different-colored layers of ceramic resins were successfully manufactured by continuous 3D printing and simultaneous sintering. This study paves the way for innovation in the manufacturing of ceramic products by 3D printing as an alternative to the traditional ceramic process.

Purpose – Foreign Exchange Rates (FER) have been one of the most significant factors for both Korean exporters and the economy of Korea. The purpose of this study is to evaluate whether exporters with a high level of Exchange Rate Elasticity of Sales (ERES) make the use of earnings management for Income Smoothing (IS). Design/methodology – Income smoothing was obtained using the methodology suggested by Leuz, Nanda and Wysocki (2003). Accruals-based Earnings Management (AEM) was estimated using Discretionary Accruals (DA) calculated by the operant Jones Model developed by Dechow, Sloan and Sweeney (1995). Real Earnings Management (REM) was obtained using the methodologies suggested by Roychowdhury (2006) and Cohen and Zarowin (2010). Data were 2,402 firm years of public listed companies on the KRX, which were not in the financial industry and had a settlement of accounts in December for the period from 2013 to 2017. Findings – Results of the evaluation are as follows. First, companies with higher levels of ERES have relatively lower levels of smoothing of reported income. This might be because a fluctuation in sales caused by an exchange rate fluctuation has a direct impact on the volatility of the reported income. Second, companies with high levels of both ERES and IS have a positive correlation with both AEM and REM. This might be because companies with high levels of IS engage in earnings management to smooth reported income. Specifically, it is possible to assume that for smoothing the reported income, not only AEM but also REM is practiced. Third, companies with high levels of ERES but low levels of IS have a negative correlation with both AEM and REM. This could be interpreted as companies exhibiting low levels of IS due to higher levels of ERES tend to control IS. In addition, such results were supported by firms relying highly on exporting, and are consequently sensitive to exchange rate fluctuation. Therefore, it may conclude that companies with high levels of ERES make the use of earnings management as a means of IS. Originality/value – This study can find its significance from the fact that it is the first study, empirically verifying that companies of Korea, where exportation is a large part, use both AEM and REM as a means for smoothing reported income upon facing exchange rate fluctuations. In addition, it is highly expected that the results of this study could be useful for participants of financial markets when making IS-related decisions.

A 3YSZ (3 mol% yttria-stabilized zirconia) ceramic green body with 50 vol% of ceramic content was 3D-printed by supportless stereolithography under optimal drying, debinding, and sintering conditions in order to achieve high strength and density. The viscosity and flowability of the ceramic nanocomposite resins were optimized by adjusting the amounts of non-reactive diluents. The ceramic 3D-printed objects have a high polymer content compared to ceramics samples manufactured by conventional manufacturing processes, and the attraction between layers is weak because of the layer-by-layer additive method. This causes problems such as layer separation and cracking due to internal stress generated when materials such as solvents and polymers are separated from the objects during the drying and debinding processes, therefore, the drying and debinding conditions of 3YSZ ceramic 3D-printed objects were optimized based on thermogravimetry&ndash, differential thermal analysis. The sintering conditions at various temperatures and times were analyzed using X-ray diffraction, SEM, and flexural strength analysis, and the body of the 3YSZ ceramic 3D-printed object that sintered at 1450 &deg, C for 150 min had a relative density of 99.95% and flexural strength of 1008.5 MPa. This study widens the possibility of manufacturing ceramic 3D-printed objects with complex shapes, remarkable strength, and unique functionality, enabling their application in various industrial fields.

Electrically conductive ceramic/polymer nanocomposites with universal percolation networks and varying contents of conductive nanoparticles were prepared herein; the effects of the dispersed state of the conductive nanoparticles on the electrical conductivity of the nanocomposites were investigated. The conductive nanocomposites were prepared by coating carbon black (CB) nanoparticles with a silane coupling agent, followed by their subsequent dispersion in the 1,6-hexanediol diacrylate (HDDA) photocurable polymer. The physical properties of the conductive nanocomposites, such as viscosity, photocurability, flowability, dispersibility, and electrical conductivity were investigated with respect to the loaded CB content. A correlation between conductivity and internal dispersibility was established by conducting theoretical analysis based on conditions of particle dispersion, aspect ratio, orientation, and interface. A comparison of the experimental values and theoretically obtained results assisted in identifying the nanoparticle network structure in the polymer matrix as universal percolation networks with imperfect/tunneling interfaces and a percolation threshold (c*) of 0.016. The electrical conductivity, heat deflection temperature (HDT), and tensile strength of 3D-printed conductive nanocomposite products were analyzed; scanning electron microscopy (SEM) was also employed to examine these samples. This study suggests a new development strategy for improving the quality of nano-products based on the quantitative dispersibility analysis of nanocomposite materials.

Flexible zeolite nanofibers with high surface area were synthesized by an electrospinning method and a thermal surface partial etching process. The thermal surface partial etching temperature range for maintaining flexibility of zeolite nanofibers was investigated based on thermogravimetric analysis (TGA), and the as-spun zeolite nanofibers were thermal etched at a temperature range from 250 °C to 450 °C. Field emission scanning electron microscope (FE-SEM) and atomic force microscope (AFM) images clearly showed that the polymer surface of the nanofibers was partially etched, and zeolite particles were exposed on the surface of the nanofibers. X-ray diffraction (XRD) results confirmed that a phase change did not occur in the zeolite nanofibers with a thermal etching process. The specific surface area characteristics were analyzed by N 2 adsorption/desorption isotherms, and the thermal surface etched zeolite nanofibers at 400 °C had a specific surface area of 816 m 2 /g similar to the value of zeolite powders.

This study investigates the poling effects on the performance of a lead-free piezoelectric nanofiber module. The lead-free piezoelectric nanofiber of 0.78Bi 0.5 Na 0.5 TiO 3 -0.22SrTiO 3 (BNT-ST) and polyvinylidenefluoride (PVDF) is prepared by an electrospinning, and the lead-free piezoelectric nanofiber modules are fabricated with the bottom and top interdigitated electrodes. The poling effects on the performance of the lead-free piezoelectric nanofiber module were investigated by XRD and temperature-dependence dielectric properties. The possibility of a flexible structural health monitoring sensor application is confirmed by measuring the output voltage of the poled and unpoled lead-free piezoelectric nanofiber modules. The flexible lead-free piezoelectric nanofiber modules are directly attached on the structure with various shapes. We expect that this system will improve the efficiency of sensing. Tests on impact detection and the structural health monitoring based on the poled and unpoled lead-free piezoelectric nanofiber modules were carried out. The monitoring results confirm the potential for estimating impact location and problems with the structure, which have been observed more obviously in the poled lead-free piezoelectric nanofiber modules.

Although it is widely accepted that corporate social responsibility (CSR) is key to obtaining business sustainability, there is a significant lack of empirical tests on the longer-term benefits of CSR in academic literature. The objective of our study was to examine the effects of chief executive officer (CEO) governance on CSR in service firms. We used CEO pay slice (CPS) to measure CEO governance and the Korea Economic Justice Institute Index (KEJI) to measure the level of CSR activities. CPS was measured using the compensation information of the board of directors in their business reports. The KEJI was obtained from the website of Citizens&rsquo, Coalition for Economic Justice. The sample selected from listed firms consisting of 260 observations was collected from 2013 to 2015 at the TS-2000 and the FnGuide. The results showed that the CPS has a significant negative impact on the level of CSR activities in service firms. Specifically, CPS has a significant negative impact on the level of CSR activities in the areas of human, environment, and society at a significant level of one percent. Based on these results, higher CEO governance is expected to mean lower CSR in service firms. This paper contributes to the field of research in that it is the first research on the relationship between CEO governance and the level of CSR activities in service firms.

In an effort to fabricate a wearable piezoelectric energy harvester based on core-shell piezoelectric yarns with external electrodes, flexible piezoelectric nanofibers of BNT-ST (0.78Bi0.5Na0.5TiO3-0.22SrTiO3) and polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE) were initially electrospun. Subsequently, core-shell piezoelectric nanofiber yarns were prepared by twining the yarns around a conductive thread. To create the outer electrode layers, the core-shell piezoelectric nanofiber yarns were braided with conductive thread. Core-shell piezoelectric nanofiber yarns with external electrodes were then directly stitched onto the fabric. In bending tests, the output voltages were investigated according to the total length, effective area, and stitching interval of the piezoelectric yarns. Stitching patterns of the piezoelectric yarns on the fabric were optimized based on these results. The output voltages of the stitched piezoelectric yarns on the fabric were improved with an increase in the pressure, and the output voltage characteristics were investigated according to various body movements of bending and pressing conditions.

Flexible lead-free piezoelectric nanofibers composites of BNT-ST (0.78Bi0.5Na0.5TiO3–0.22SrTiO3) ceramic and polyvinylidenefluoride (PVDF) polymer were synthesized by an electrospinning method. The as-prepared BNT-ST/PVDF nanofibers composite with different BNT-ST concentrations from 0 wt% to 80 wt% were characterized by XRD, FE-SEM and EDS to investigate the crystal structure, microstructure and morphology. The piezoelectric characteristics were analyzed by the polarization-electric field (P-E) loops, and the results demonstrated that a BNT-ST content of 60 wt% had enhanced piezoelectric characteristics. The possibility of frequency sensor application was confirmed by measuring the output voltage as a function of the frequency of the BNT-ST/PVDF nanofiber composite with a BNT-ST content of 60 wt%.

최근 국내 철도는 고속화와 통과톤수(MGT)의 증가에 의해 보다 높은 수준의 궤도 안정성과 내구성을 확보하기 위하여 엄밀 하면서도 새로운 궤도노반 분류기준의 재정립이 요구되고 있다. 현재 해외 철도 선진국은 대부분 자국 내 철도 궤도 노반전용 의 흙재료 분류기준을 제정하여 사용하고 있다. 일본의 경우 철도총합기술연구소(RTRI)에서 2007년에 간행한 ‘철도구조물등 설 계표준 동해설[1]’을 통하여 성토구간 흙쌓기용 재료분류기준을 새롭게 제시한 바 있다. 독일 또한 자체의 독자적 흙분류기준을 제정하여 사용하고 있다[2]. 이는 독일이 위치한 고유의 지형학적 토질분류 특성을 반영하도록 한 것이며, 매우 엄밀한 노반전 Abstract The soils used as trackbed in Korea are selected using USCS utilizing basic soil properties such as Grain Size Distribution(GSD), % passing of #200 sieve (P200), % passing of #4 sieve (P4), Coefficient of uniformity (Cu), and Coefficient of curvature (Cc). Degree of compaction of the soils adapted in the code by KR should be evaluated by maximum dry density (γd-max) and deformation modulus Ev2. The most important influencing factor that is critical to stability and deformation of the compacted soils used as trackbed is stiffness. Thus, it is necessary to construct a correlation between the modulus and the basic soil properties of trackbed soil in order to redefine a new soil classification system adaptable only to railway construction. To construct the relationship, basic soil test data is collected as a database, including GSD, maximum dry unit weight (γd-max), OMC, P200, P4, Cu, Cc, etc.; deformation modulus Ev2 and Evd are obtained independently by performing a Repeated Plated Bearing Test (RPBT) and Light Weight Deflectometer Test (LWDT) for ten different railway construction sites. A linear regression analysis is performed using SPSS to obtain the relationship between the basic soil properties and the deformation modulus Ev2 and Ev. Based on the constructed relationship and the various obtained mechanical test data, a new soil classification system will be proposed later as a guideline for the design and construction of trackbed foundation in Korea.

Recently, the development of the Marina port is determined as a national plan, and a variety of leisure boats and facilities on the field has been of critical interest. In particular, yachts are designed and produced mostly at small shipbuilding companies and research institute. The regulation and historic data, however, about the safety of structure are not readily available. Therefore, it is required to evaluate the strength of ship structure. This paper deals with the estimation of local strength of 40 feet sailing yacht by using finite element analysis. The forebody, mast and connection parts of a FRP yacht structure are evaluated. In addition, the results are compared with the regulation of Lloyd's register and Korean register.

Flexible lead-free piezoelectric nanofibers, based on BNT-ST (0.78Bi0.5Na0.5TiO3-0.22SrTiO3) ceramic and poly(vinylidene fluoride-trifluoroethylene) (PVDF-TrFE) copolymers, were fabricated by an electrospinning method and the effects of the degree of alignment in the nanofibers on the piezoelectric characteristics were investigated. The microstructure of the lead-free piezoelectric nanofibers was observed by field emission scanning electron microscope (FE-SEM) and the orientation was analyzed by fast Fourier transform (FFT) images. X-ray diffraction (XRD) analysis confirmed that the phase was not changed by the electrospinning process and maintained a perovskite phase. Polarization-electric field (P-E) loops and piezoresponse force microscopy (PFM) were used to investigate the piezoelectric properties of the piezoelectric nanofibers, according to the degree of alignment—the well aligned piezoelectric nanofibers had higher piezoelectric properties. Furthermore, the output voltage of the aligned lead-free piezoelectric nanofibers was measured according to the vibration frequency and the bending motion and the aligned piezoelectric nanofibers with a collector rotation speed of 1500 rpm performed the best.

Objective: To determine the impact of p53 overexpression on tumor recurrence after bacillus Calmette-Guérin (BCG) intravesical therapy in patients with nonmuscle invasive bladder cancer (NMIBC). Methods: Between January 1999 and December 2008, 275 patients who received six BCG intravesical instillations for NMIBC (transitional cell carcinoma) after transurethral resection were assessed for differences in outcomes according to the level of p53 overexpression. A multivariate logistic regression model was applied to assess the predictive capacity of variables for recurrence. Overexpression of p53 was determined using monoclonal p53-DO7 antibody. Results: In 275 subjects, the recurrence rate was higher based on the level of p53 expression (p = 0.019). Based on multivariate analysis, a strong-positive p53 >60% (p = 0.031) and tumor grade (p = 0.015) were significant predictors for recurrence. Patients with a strong-positive p53 >60% had a much lower 5-year biochemical recurrence-free survival rate than patients with p53 ≤60% (72.1 vs. 31.5%, p < 0.001). Conclusions: Strong overexpression of p53 was predictive of recurrence in patients with NMIBC undergoing intravesical BCG treatment. A 6-week induction course of BCG alone is not sufficient to prevent recurrence in patients with NMIBC with high p53 expression; additional prophylactic strategies are needed for these patients.

A combined run-to-run (R2R) and LQG control method has been proposed for rapid thermal processing (RTP) equipment for run-wise improvement and real-time multivariable control of the temperature uniformity over the wafer surface. The standard LQG objective was modified to include a quadratic penalty term for input deviation from bias values which are updated by an R2R control law. The proposed method has been applied to commercial 12-inch rotating RTP equipment with four pyrometers and ten circular groups of tungsten-halogen lamps for measurements and manipulation of wafer temperatures. The performance of LQG control was evaluated under wafer rotation and found to show quite accurate tracking. For evaluation of the combined control technique, a wafer with seven thermocouples (TC’s) attached along the radial direction has been employed for the TC measurements to be used for R2R control, whereas the pyrometer measurements are fed back for real-time LQG control. It was observed that the temperature uniformity is improved as the run number increases.

A simple, single-well push-pull test was conducted at a TCE-contaminated site to estimate the site-specific TCE degradation and permanganate (MnO 4 − ) consumption rate. Known quantities of a conservative tracer (Br−) and permanganate were rapidly injected into a saturated aquifer then periodically sampled during extraction from the same well. Concentrations of Br−, TCE, and MnO 4 − were measured; breakthrough curves (BTCs) for all species of solute were determined. Data analysis of BTCs for bromide and TCE showed that the first-order rate constant of TCE degradation by MnO 4 − is 1.67 ± 0.152 h−1. Further, the in situ MnO 4 − demand rate by TCE and aquifer materials is estimated to be 0.54 ± 0.371 h−1. This study demonstrates that in situ push-pull tests are useful and economical tools for field investigations to determine contaminant reaction and oxidant consumption rates, which may then be used to optimize groundwater remediation designs.

The increase of computing power makes stochastic optimization algorithms available in structural design. One of the stochastic algorithms, simulated annealing algorithm, has been applied to various structural optimization problems. By applying several cooling schedules such as simulated annealing (SA), Boltzmann annealing (BA), fast annealing (FA) and adaptive simulated annealing (ASA), truss structures are optimized to improve the quality of objective functions and reduce the number of function evaluations. In this paper, many cooling parameters have been applied to the cooling schedule of ASA. The influence of cooling parameters is investigated to find the rules of thumb for using ASA. Tn addition, the cooling schedule combined with BA and ASA is applied to the optimization of ten bar-truss and twenty five bar-truss structure.

A constrained iterative learning control (ILC) technique based on a delta-form linear quadratic Gaussian (LQG) technique has been designed for overcoming model error and for numerically stable control of a rapid thermal processing(RTP). The RTP is characterized by very short sampling time and repetition of single batch. The delta form LQG control technique was applied for accurate control in high frequency caused by short sampling time. The designed control technique, ILC, acquired both numerically stable and to overcome model error in combination with the multivariable delta form LQG technique. A structural problem of the equipment or an excessive model error may cause physically unreasonable solution computed by the delta form LQG. For this, Constraints were applied to the ILC solution to be placed on the physically reasonable area. Cubic spline approximation was used as a numerical method to approximate time-varying gain matrices. The method remarkably reduced not only a computation time, but also a data transmission time from computer to DSP board in RTP equipment. In the results of simulation, control performance was improved from batch to batch, and finally reached specification-satisfied wafer's temperature uniformity with physically reasonable lamp powers. The proposed control technique was designed for commercial RTP equipment which has 10 tungsten-halogen lamp groups and 6 pyrometers installed for heating and measure a 12-inch wafer.