A Study on Verification of the Dynamic Modeling for a Submerged Body Based on Numerical Simulation

This study proposed a procedure to identify maneuvering coefficients that brought about abnormal motions in the simulation of a submerged body. The first step in responding to abnormal motions was conducting stability analysis to determine whether the submerged body could be simulated. If doing so was feasible, sensitivity analysis was then performed to determine maneuvering coefficients that caused the abnormal motion in the simulation. Finally, we analyzed the order of maneuvering coefficients identified by the sensitivity analysis. We also compared it with empirical formulas and other results obtained from model tests. The dynamics model targeting a high-speed submerged body was indirectly verified by the above procedure. In this study, the effectiveness of the dynamic model was verified, and parameters causing the abnormal motion were identified in accordance with the developed procedure

Sensitization of organic photovoltaic cells based on interlayer excitation energy transfer

We incorporated an additional p-type organic semiconductor layer (APL) between the anode and the phthalocyanine layer, which is an indispensable p-type semiconductor layer (IPL) in forming a p/n junction with a fullerene C-60 layer. We used two thiophene/phenylene co-oligomers as the APL. The incorporation increases the short-circuit current density (J(SC)) and enhances incident photon-current conversion efficiency (IPCE) over the wavelength region where the APL shows strong absorption. Combined dependence of the APL/IPL implies that Forster resonance excitation transfer is the main factor in J(SC) and IPCE enhancements. We demonstrate clearly that the 'positive' hole injection barrier at the interface between the APL and the IPL impacts the smooth transportation of holes to the indium-tin-oxide anode. However, the small positive hole barrier of 0.1 eV has no noticeable influence on the fill factor of the current density versus voltage characteristic under photoirradiation, or on those devices with 'negative' hole barriers.ArticleOrganic Electronics. 11(4):700-704 (2010)journal articl

Cascade-Type Excitation Energy Relay in Organic Thin-Film Solar Cells

ArticleORGANIC ELECTRONICS. 14(3):814-820 (2013)journal articl

Enhancing spectral contrast in organic red-light photodetectors based on a light-absorbing and exciton-blocking layered system

This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in JOURNAL OF APPLIED PHYSICS. 108(3):034502 (2010) and may be found at https://doi.org/10.1063/1.3466766 .We demonstrated a highly sensitive red-light photodetector based on a mixed copper phthalocyanine (CuPc) and fullerene C-60 photoactive layer, similar to a so-called bulk heterojunction structure usually used in the field of organic photovoltaics. We incorporated an additional set of organic layers that was composed of two organic p-type semiconductors to reduce the blue-light sensitivities of CuPc- and C-60-based organic photodetectors. We used alpha, omega-diphenyl sexi-thiophene (P6T) and alpha, omega-bis(biphenyl-4-yl)ter-thiophene (BP3T), which are thiophene-based materials and usually have good hole-transporting properties. A thick (>100 nm) P6T layer absorbed blue light, preventing it from reaching the photoactive layer, and a thin (similar to 20 nm) BP3T layer whose band gap was larger than that of P6T blocked excitation energy transfer from P6T to CuPc. Thus, we successfully demonstrated a red-light photodetector with high peak sensitivity and whose current-voltage characteristics did not worsen. The optimal device showed a peak incident photon-current conversion efficiency of 51.7% at 620 nm and a specific detectivity of 4.0 X 10(11) cm Hz(1/2)/W.ArticleJOURNAL OF APPLIED PHYSICS. 108(3):034502 (2010)journal articl

Effects of volatile additives in solutions used to prepare polythiophene-based thin-film transistors

We investigate the effects of volatile additives in solutions used to prepare thin-film transistors (TFTs) of regioregular poly(3-hexylthiophene) (P3HT). We use the additives trifluoromethylbenzene (TFMB) and methylcyclohexane (MCH) because they are poor solvents for P3HT. The additives improve the performance of the resulting TFTs when the boiling point (T(b)) of the major solvent, carbon tetrachloride, is lower than that of the additive. The maximum mobility is (4.0 +/- 60.9) x 10(-2) cm(2)V(-1)s(-1), which is 6.1 times larger than that of TFTs prepared without TFMB or MCH added to the solution; the on/off ratio and the subthreshold slope were also improved. The relative T(b) of the solvent and the additive affected the film formation with the amount of TFMB or MCH remaining at the final stage of thin film deposition influencing the precipitation of P3HT aggregates. (C) 2011 American Institute of Physics. [doi:10.1063/1.3553878]ArticleJOURNAL OF APPLIED PHYSICS. 109(5):54504 (2011)journal articl

Hi,KIA: A Speech Emotion Recognition Dataset for Wake-Up Words

Wake-up words (WUW) is a short sentence used to activate a speech recognition system to receive the user's speech input. WUW utterances include not only the lexical information for waking up the system but also non-lexical information such as speaker identity or emotion. In particular, recognizing the user's emotional state may elaborate the voice communication. However, there is few dataset where the emotional state of the WUW utterances is labeled. In this paper, we introduce Hi, KIA, a new WUW dataset which consists of 488 Korean accent emotional utterances collected from four male and four female speakers and each of utterances is labeled with four emotional states including anger, happy, sad, or neutral. We present the step-by-step procedure to build the dataset, covering scenario selection, post-processing, and human validation for label agreement. Also, we provide two classification models for WUW speech emotion recognition using the dataset. One is based on traditional hand-craft features and the other is a transfer-learning approach using a pre-trained neural network. These classification models could be used as benchmarks in further research.Comment: Asia Pacific Signal and Information Processing Association Annual Summit and Conference (APSIPA), 202

N,N'-Diphenylperylene Diimide Functioning as a Sensitizing Light Absorber for Organic Thin-Film Solar Cells

ArticleORGANIC ELECTRONICS. 14(2):464-468 (2013)journal articl

Bipyridyl-substituted benzo[1,2,3]triazoles as a thermally stable electron transporting material for organic light-emitting devices

We developed new electron-transporting materials (ETMs) for organic light-emitting devices (OLEDs) based on benzo[1,2,3] triazole and two bipyridines. Four derivatives based on the same skeleton were synthesized with four different substituents: phenyl (BpyBTAZ-Ph), biphenyl (-BP), m-terphenyl (-mTP), and o-terphenyl (-oTP). These BpyBTAZ compounds have good thermal stabilities, and their decomposition temperatures were greater than 410 degrees C, which is significantly higher than that of tris(8-quinolinolato) aluminium (Alq), the conventional OLED material. BpyBTAZ compounds show preferable amorphous nature, and moreover, the glass transition temperatures (T(g)s) of both BpyBTAZ-TP compounds exceed 100 degrees C. Furthermore, BpyBTAZ-BP exhibits no melting point and is fully amorphous. The electron affinities of the materials are as large as 3.3 eV and their electron mobility is sufficiently high. These characteristics accounted for a reduction in the operational voltage of OLEDs with BpyBTAZ compounds compared with the reference device with Alq as an ETM. Specifically, the electron mobility of all the BpyBTAZ compounds exceeds 1 x 10(-4) cm(2) V(-1) s(-1) at an electric field of 1 MV cm(-1). In addition, it was revealed that both BpyBTAZ-TP-based devices showed longer luminous lifetimes and smaller voltage increases during continuous operation at 50 mA cm(-2), compared with the Alq reference device.ArticleJOURNAL OF MATERIALS CHEMISTRY. 21(32):11791-11799 (2011)journal articl

A highly efficient sublimation purification system using baffles with orifices

Here we report a highly efficient sublimation purification system using baffles with orifices in the sublimation tube. It is clearly demonstrated that the purity of materials is increased largely by introducing some pieces of baffles with orifices in the high-temperature region (sublimation region), which was confirmed by comparing the melting point (T-m) and the high-performance liquid chromatography (HPLC) purity with those of purified one by a conventional system. The driving voltages of electroluminescence (EL) devices were also compared and showed the same tendency with the T-m and HPLC purity data. Not only the purity but also the effective yield of purified materials was also increased by introducing baffles in low-temperature region. Some expected mechanisms of improving the purification efficiency by introducing baffles were also discussed.ArticleOrganic Electronics. 11(5):794-800 (2010)journal articl

Large-scale Text-to-Image Generation Models for Visual Artists' Creative Works

Large-scale Text-to-image Generation Models (LTGMs) (e.g., DALL-E), self-supervised deep learning models trained on a huge dataset, have demonstrated the capacity for generating high-quality open-domain images from multi-modal input. Although they can even produce anthropomorphized versions of objects and animals, combine irrelevant concepts in reasonable ways, and give variation to any user-provided images, we witnessed such rapid technological advancement left many visual artists disoriented in leveraging LTGMs more actively in their creative works. Our goal in this work is to understand how visual artists would adopt LTGMs to support their creative works. To this end, we conducted an interview study as well as a systematic literature review of 72 system/application papers for a thorough examination. A total of 28 visual artists covering 35 distinct visual art domains acknowledged LTGMs' versatile roles with high usability to support creative works in automating the creation process (i.e., automation), expanding their ideas (i.e., exploration), and facilitating or arbitrating in communication (i.e., mediation). We conclude by providing four design guidelines that future researchers can refer to in making intelligent user interfaces using LTGMs.Comment: 15 pages, 3 figure