Browsing by Issue Date, starting with "2010-01-20"

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交大e-News第064期
(2010-01-20)
Secretariat
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國立交通大學秘書室
Construction and characteristics of tandem organic solar cells featuring small molecule-based films on polymer-based subcells
(2010-01-20)
Chen, Fang-Chung
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Lin, Cheng-Hao
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光電工程學系
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顯示科技研究所
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Department of Photonics
In this study, we stacked a small molecule-based cell onto another polymer-based device to fabricate a tandem organic solar cell that extended the absorption range of the entire cell over a wider spectral range. Between the two subcells, we positioned a connecting structure comprising layers of Cs(2)CO(3), Ag and MoO(3). Current matching phenomena played an important role in determining the device efficiency. The judicious selection of subcells exhibiting superior current matching improved the performance of the tandem cell. Indeed, in the optimally performing tandem cells we obtained both a high open-circuit voltage (1.21 V) and an improved power conversion efficiency (1.81%). From analyses of the surface morphology and transmission spectra of the middle Ag layers, we deduced that the main function of this film was to provide more sites for efficient recombination of holes and electrons. The thickness of this layer was limited by its transmittance. A thinner Ag layer allowed more light to be harvested by the top cell, increasing the overall performance of the tandem cell.
Absolute time delay generating device
(2010-01-21)
Lee, Chen-Yi
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Yu, Jui-Yuan
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Yu, Chien-Ying
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Chen, Juinn-Ting
An absolute time delay generating device includes a PVT (process-voltage-temperature) detection device and a delay-timing generator. The PVT detection device includes at least a delay module and a signal phase/frequency control module. The delay module includes a control unit and a reference unit. The control unit differs from the reference unit in sensitivity of delay property to PVT. The delay module compares phase or frequency differences generated when origin signals pass through the control unit and reference unit respectively, and produce delay parameters of the delay module. The signal phase/frequency control module receives and compares the delay parameters to determine an ambient PVT condition for the absolute time delay generating device, so as to control and correct the delay-timing generator and thereby generate accurate absolute time delay. Under various PVT influences, the absolute time delay generating device is capable of generating accurate, absolute time signals.
MEMORY-BASED FFT/IFFT PROCESSOR AND DESIGN METHOD FOR GENERAL SIZED MEMORY-BASED FFT PROCESSOR
(2010-01-21)
LEE, Chen-Yi
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Hsiao, Chen-Fong
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Chen, Yuan
For a large size FFT computation, this invention decomposes it into several smaller sizes FFT by decomposition equation and then transform the original index from one dimension into multi-dimension vector. By controlling the index vector, this invention could distribute the input data into different memory banks such that both the in-place policy for computation and the multi-bank memory for high-radix structure could be supported simultaneously without memory conflict. Besides, in order to keep memory conflict-free when the in-place policy is also adopted for I/O data, this invention reverses the decompose order of FFT to satisfy the vector reverse behavior. This invention can minimize the area and reduce the necessary clock rate effectively for general sized memory-based FFT processor design.
Revisiting anomalous structures in liquid Ga
(2010-01-21)
Tsai, K. H.
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Wu, Ten-Ming
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Tsay, Shiow-Fon
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物理研究所
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Institute of Physics
In terms of an interatomic pair potential, which well characterizes the dynamic properties of liquid Ga, we investigate again the origin of the well known high-q shoulder in the static structure factor of the liquid. Similar to the results of Gong's simulation at high temperature, dimers with extremely short bond lengths are indeed found in our model just above the melting point, but our results indicate that it is unlikely for the high-q shoulder to be produced by these dimers. Instead, based on our model, the high-q shoulder is resulted from some medium-range order, which is related to the structures beyond the first shell of the radial distribution function, caused by Friedel oscillations within a nanoscale range.
Polytriazole/clay nanocomposites synthesized using in situ polymerization and click chemistry
(2010-01-21)
Ye, Yun-Sheng
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Yen, Ying-Chieh
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Cheng, Chih-Chia
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Syu, Yu-Jyuan
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Huang, Yao-Jeng
This manuscript describes the preparation of polytriazole/clay nanocomposites through in situ polymerization of PTA, using click chemistry, in the presence of a propargyl-modified clay. The clay layers became exfoliated and dispersed well in the PTA matrix, thereby improving the thermal and mechanical properties of the clay. This approach can be extended to combine propargyl-modified clays with other azide- and alkyne-containing polymers. (C) 2009 Elsevier Ltd. All rights reserved.
DIGITAL DELAY LINE AND APPLICATION THEREOF
(2010-01-21)
LEE, Chen-Yi
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Yu, Jui-Yuan
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Chen, Juinn-Ting
A digital delay line includes a plurality of hysteresis-based delay cells electrically connected in series. These hystersis delay units in the hysteresis-based delay cells may be similar or different. All of the hysteresis delay units respectively have an inverter mode and a hesteresis mode. The delay and resolution of the hysteresis delay unit may be derived from the time difference in the inverter mode and hysteresis mode. Such a digital delay line applied to a digital phase locked loop may reduce consumption of area and power.
Electrical characteristics of an organic bistable device using an Al/Alq(3)/nanostructured MoO3/Alq(3)/p(+)-Si structure
(2010-01-25)
Chang, Tzu-Yueh
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Cheng, You-Wei
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Lee, Po-Tsung
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光電工程學系
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顯示科技研究所
The electrical properties of a device with an Al/Alq(3)/nanostructured MoO3/Alq(3)/p(+)-Si structure were investigated for organic resistance switching memories. The conductance of the device can be electrically switched to either high conductance or low conductance. The bistable switching of the device is attributed to the MoO3 nanoclusterlike layer interposed between the Alq(3) thin films. When the device was switched to high conductance, a space-charge field dominated carrier transportation of the device. The space-charge field was resulted from charges trapped in the MoO3 nanoclusterlike layer. Both retention measurement and write-read-erase-read cycles of the device are also provided.
Electrical characteristics of an organic bistable device using an Al/Alq(3)/nanostructured MoO(3)/Alq(3)/p(+)-Si structure
(2010-01-25)
Chang, Tzu-Yueh
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Cheng, You-Wei
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Lee, Po-Tsung
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光電工程學系
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顯示科技研究所
The electrical properties of a device with an Al/Alq(3)/nanostructured MoO(3)/Alq(3)/p(+)-Si structure were investigated for organic resistance switching memories. The conductance of the device can be electrically switched to either high conductance or low conductance. The bistable switching of the device is attributed to the MoO(3) nanoclusterlike layer interposed between the Alq(3) thin films. When the device was switched to high conductance, a space-charge field dominated carrier transportation of the device. The space-charge field was resulted from charges trapped in the MoO(3) nanoclusterlike layer. Both retention measurement and write-read-erase-read cycles of the device are also provided.
Polymer photodetector with voltage-adjustable photocurrent spectrum
(2010-01-25)
Chen, En-
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Chang, Chia-Yu
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Shieh, Ji-Ting
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Tseng, Shin-Rong
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Meng, Hsin-Fei
Polymer photodetectors with voltage-adjustable photoresponse from visible to near infrared range are demonstrated. Poly(3-hexylthiophene) and (6,6)-phenyl-C61-butyric acid methyl ester (PCBM) blend is used as the active layer. The photoresponse can be continuously adjusted by the thickness of the active layer as well as the applied voltage bias. The thickness of the active layer is varied from 250 nm to 16.2 mu m. The mechanism for the photoresponse adjusted by the thickness can be attributed to the absorption of the photons in the infrared range by thick PCBM layer. The mechanism for the photoresponse adjusted by the applied bias can be attributed to the carrier recombination reduction when the applied bias increases. The adjustable photodetector also has high operating speed up to 10 kHz.
Method for power-efficient transmission supporting integrated services over wireless local area network
(2010-01-26)
Shih
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Chih-Yung
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Cheng
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Ray-Guang
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Chang
This invention provides a method for power-efficient transmission supporting integrated service over WLAN. The said invention combines the polling-based and the contention-based mechanisms, named on-demand polling (ODP). In the ODP scheme, a voice station is in the polling list when it is in the active mode. During the idle mode, it is configured to operate in the sleep mode for saving power. Also, it adopts the contention-based mechanism to join the list again while returning from the idle mode. On the other hand, the data station adopts the contention-based mechanism to transmit its packets over WLAN. In addition, to achieve service differentiation, the said invention also employs a prioritized access probability for voice over data services. Simulation results show that the said invention can reduce the power consumption for voice stations and enhance the throughput for data stations.
On Modulating the Phase Behavior of Block Copolymer/Homopolymer Blends via Hydrogen Bonding
(2010-01-26)
Chen, Shih-Chien
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Kuo, Shiao-Wei
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Jeng, U-Ser
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Su, Chun-Jen
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Chang, Feng-Chih
We have investigated the phase behavior or poly(4-vinylphenol-b-styrene) (PVPh-b-PS) when respectively blended with poly(4-vinylpyridine) (NVP), poly(methyl methacrylate) (PMMA), and PVPh homopolymers by mediated hydrogen bonding strengths with the PVPh block of the copolymer. The Fourier transform infrared spectroscopic result indicates that the PVPh-b-PS/P4VP blend has a much higher fraction (f(H)) of hydrogen-bonded PVPh blocks for it significantly higher miscibility compared with the blends with PMMA and PVPh homopolymers. Consequently, the PVPh-b-PS/P4VP blend, behaving as a neat diblock copolymer, exhibited a series of order-order phase transitions from the lamellar, gyroid, hexagonally packed cylinder to body-centered cubic structures when the P4VP content increases from 6 to 71% (volume fraction), as evidenced consistently by transmission electron microscopy and small-angle X-ray scattering. In contrast, both file PVPh-b-PS/PMMA and PVPh-b-PS/PVPh blends maintained essentially the lamellar structure upon a similar volume fraction increase in the homopolymers; the lamellar structure, however, was distorted to different extents at higher volume fractions of the additives, depending on the hydrogen bonding strength. On the basis of the results, the ratio of interassociation equilibrium constant (KA) over self-association equilibrium constant (K(B)), K(A)/K(B), is introduced as a convenient guide in estimating the phase behavior of similar polymer blends featuring hydrogen bonding interactions between file homopolymer additive and copolymer: with a K(A)/K(B) ratio much larger than unity, the blend system tends to behave as a neat copolymer; with a K(A)/K(B) ratio significantly smaller than unity, phase separation instead of order-order phase transitions call be expected for the blend above certain volume fraction of homopolymer additive.
Synthesis and Characterization of Bridged Bithiophene-Based Conjugated Polymers for Photovoltaic Applications: Acceptor Strength and Ternary Blends
(2010-01-26)
Chen, Chiu-Hsiang
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Hsieh, Chao-Hsiang
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Dubosc, Martin
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Cheng, Yen-Ju
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Su, Chain-Shu
Six of three-component donor-acceptor random copolymers P1-P6, symbolized as (thiophene donor)(m)-(thiophene acceptor)(n), were rationally designed and successfully synthesized by the palladium-catalyzed Stille Coupling, The 4H-cyclopenta[2, 1-b:3,4-b']dithiophene (CPDT) unit serves as the donor for P1-P4, while file benzothiadiazole (BT), quinoxaline (QU), dithienoquinoxaline, and thienopyrazine (TP) units are used as the acceptor for P1, P2, P3, and P4, respectively. P5 and P6 are structurally analogous to P1 and P2 except for using the dithieno[3.2-b:2',3'-d]silole (DTS) unit as the donor. Because the band gap lowering ability of the acceptor units in the polymer is in the order TP > BR > QU presumably due to the quinoid form Population in the polymers, the optical band gaps call be well adjusted to be 1.2, 1.6, and 1.8 eV for P4, P1, and P2, respectively. It is found that file two bridged bithiophene units, CPDT and DTS, have similar steric and electronic effects oil the P1 and P5 as well as P2 and P6, respectively, leading to comparable intrinsic properties and device performances. Bulk heterojunction photovoltaic cells based oil ITO/PEDOT:PSS/polymer:PC(71)BM/Ca/Al configuration were fabricated and characterized. Although P4 exhibits the lowest optical band gap, broadest absorption spectrum, and highest mobility, the too low-lying LUMO level hinders the efficient exciton dissociation, resulting in a low PCE of 0.7%. Compared with poly[2,6-(4,4-bis(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b']dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)] (PCPDTBT), random copolymer P1 shows more blue-shifted, broader absorption spectrum, comparable mobility, and a higher PCE of 2.0%. In view of the fact that P1 shows it higher band gap with strong absorption in visible region, while PCPDTBT-has a lower band gap to mainly absorb NIR light, a BHJ device with the active layer containing ternary blend of PCPDTBT/P(1)/PC(71)BM was investigated and achieved an enhanced PCE of 2.5%, which outperforms the devices based on the binary blending systems of PCPDTBT/PC7, BM (PCE = 1.4%) or P1/PC(71) BM (PCE = 2.0%,,) Linder the identical conditions. Such an improvement is ascribed to file complementary absorption and compatible structure of P1 and PCPDTBT polymers.
Anticancer and Antioxidant Activities of the Peptide Fraction from Algae Protein Waste
(2010-01-27)
Sheih, I-Chuan
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Fang, Tony J.
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Wu, Tung-Kung
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Lin, Peng-Hsiang
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生物科技學系
Algae protein waste is a byproduct during production of algae essence from Chlorella vulgaris. There is no known report on the anticancer peptides derived from the microalgae protein waste. In this paper, the peptide fraction isolated from pepsin hydrolysate of algae protein waste had strong dose-dependent antiproliferation and induced a post-G1 cell cycle arrest in AGS cells; however, no cytotoxicity was observed in WI-38 lung fibroblasts cells in vitro. The peptide fraction also revealed much better antioxidant activity toward peroxyl radicals and LDL than those of Trolox. Among these peptides, a potent antiproliferative, antioxidant, and NO-production-inhibiting hendecapeptide was isolated, and its amino acid sequence was VECYGPNRPQF. These results demonstrate that inexpensive algae protein waste could be a new alternative to produce anticancer peptides.
WHITE-EMITTING PHOSPHORS AND LIGHTING APPARATUS USING THE SAME
(2010-01-28)
Chen, Teng-Ming
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Chang, Chun-Kuei
A phosphor has a general formula of (M1-m-nCemEun)3Al2O5X2, wherein M is at least one selected from the group consisting of Ca, Sr and Ba; and X is at least one selected from the group consisting of Cl and Br, while 0
Covering graphs with matchings of fixed size
(2010-01-28)
Cariolaro, David
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Fu, Hung-Lin
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應用數學系
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Department of Applied Mathematics
Let m be a positive integer and let G be a graph. We consider the question: can the edge set E(G) of G be expressed as the union of a set M of matchings of G each of which has size exactly m? If this happens, we say that G is [m]-coverable and we call M an [m]-covering of G. It is interesting to consider minimum [m]-coverings, i.e. [m]-coverings containing as few matchings as possible. Such [m]-coverings will be called excessive [m]-factolizations. The number of matchings in an excessive [m]-factorization is a graph parameter which will be called the excessive [m]-index and denoted by chi([m])'. In this paper we begin the study of this new parameter as well as of a number of other related graph parameters. (C) 2008 Elsevier B.V. All rights reserved.
Apparatus and method for forming multilayer polymer thin film
(2010-01-28)
Meng, Hsin-Fei
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Horng, Sheng-Fu
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Tseng, Hsin-Rong
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Tuan, Chi-Shen
Apparatus and method for forming multilayer polymer thin film. The method uses a solution container with a gap to prevent the huge amount of solution from directly falling on the first layer. Then the wet film is formed by moving the container with the thin film thickness is decided by the distance between the gap and the substrate. The wet film is dried in a very short time by the heater therefore there is no time for the second solvent to dissolve the first layer. The method can effectively achieve the large-area and multilayer structure in organic devices through solution processing.
Elliptic equations in highly heterogeneous porous media
(2010-01-30)
Yeh, Li-Ming
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應用數學系
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Department of Applied Mathematics
Uniform estimate and convergence for highly heterogeneous elliptic equations are concerned. The domain considered consists of a connected fractured subregion (with high permeability) and a disconnected matrix block subregion (with low permeability). Let epsilon denote the size ratio of one matrix block to the whole domain and let the permeability ratio of the matrix block region to the fractured region be of the order epsilon(2). In the fractured region, uniform Holder and uniform Lipschitz estimates in epsilon of the elliptic solutions are derived; the convergence of the solutions in L(infinity) norm is obtained as well. Copyright (C) 2009 John Wiley & Sons, Ltd.
Improved crystal quality and performance of GaN-based light-emitting diodes by decreasing the slanted angle of patterned sapphire
(2010-02-01)
Cheng, Ji-Hao
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Wu, YewChung Sermon
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Liao, Wei-Chih
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Lin, Bo-Wen
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材料科學與工程學系
Periodic triangle pyramidal array patterned sapphire substrates (PSSs) with various slanted angles were fabricated by wet etching. It was found beside normal wurtzite GaN, zinc blende GaN was found on the sidewall surfaces of PSS. The crystal quality and performance of PSS-LEDs improved with decrease in slanted angle from 57.4 degrees to 31.6 degrees. This is because most of the growth of GaN was initiated from c-planes. As the growth time increased, GaN epilayers on the bottom c-plane covered these pyramids by lateral growth causing the threading dislocation to bend toward the pyramids.
Effect of Practice on Stepping Movements Onto Laterally Compliant Raised Structures: Age Differences in Healthy Males
(2010-02-01)
Yang, Bing-Shiang
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Ashton-Miller, James A.
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機械工程學系
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Department of Mechanical Engineering
Objective: The aim of this study was to examine effects of practice and age on step-up movements onto raised structures. Background: Falls from laterally compliant structures, such as stepladders, often cause injuries in elderly persons. Although age differences in step-up movements onto raised structures with unexpected structural compliance have been reported, practice effects of such movement control have not been investigated. Method: Movement behavior of 20 healthy adults (10 young and 10 older males) was measured while they stepped up onto a raised structure with no compliance (i.e., rigid) (C(0)), a small amount of mediolateral compliance (C(1)), or greater mediolateral compliance (C(2)). The conditions C(0), C(1), and C(2) were presented in three sets of six fixed-order trials with step-up movements performed at a comfortable speed. Practice effects in step-up behavior were examined by comparing data within each trial block with the use of repeated-measures ANOVA. Results: Practice significantly reduced the stepping duration (Ts) needed to complete the step-up movement (p < .001). With practice, older males reduced their lateral oscillations 26% to 40% for C(1) and C(2), whereas the corresponding results for young males lay between 8% and 17%, respectively. The age difference in Ts decreased across six consecutive trials but remained significant, especially on the structure with greater compliance. Conclusion: With practice, both young and elderly men adapted their stepping behavior to the presence of lateral structural compliance, but it is noteworthy from a fall-injury prevention perspective that the elderly men required more trials to do so. Application: Designers and users of raised structures, such as stepladders, should be aware of the age difference of people using such structures and should minimize the structure compliance when designing them.