• Proceedings of the Korean Society of Computer Information Conference
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• 2010.07a
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• pp.301-306
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• 2010

본 연구는 창업분야의 공공부문 정보시스템인 BI-Net의 활용성을 제고하기 위한 요인들을 살펴보고자 한다. 이를 위하여 정보시스템의 성과를 측정하기 위한 정보시스템 성공모델과 기술수용과 사용에 관한 통합이론을 기반으로 BI-Net의 사용의도에 영향을 주는 요인들과의 관계를 실증분석을 통하여 파악하였다. 실증분석 결과 정보품질 및 시스템품질과 성과기대가 사용자 만족도에 영향을 주는 것으로 나타났으며, 정보품질 및 시스템품질과 성과기대 및 노력기대가 BI-Net의 사용의도에 영향을 주는 요인인 것으로 나타났다. 또한 운영평가수준과 사용자 성별이 사용의도와 영향요인과의 관계에서 조절효과가 있는 것으로 나타났다. 이러한 결과를 바탕으로 사용자 만족을 위해서 BI-Net의 품질수준을 높이는 것이 중요하며, BI-Net의 사용의도를 높이기 위해서는 사용자 만족과 함께 시스템에 대한 기대수준을 높여야 함을 제시하였다. 또한 창업보육센터의 상황과 사용자에 적합하게 시스템을 설계하는 것도 BI-Net의 사용의도를 높이는 방법임을 제시하였다.

• Journal of the Korean Physical Society
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• v.73 no.11
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• pp.1684-1690
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• 2018

The layered semiconductors $Bi_2O_2Q$ (Q = S, Se) consists of $Bi_2O_2$ layers sandwiched by Q square nets. On the basis of density functional theory calculations, we examined the thermoelectric properties of $Bi_2O_2S$, $Bi_2O_2Se$ as well as hypothetical structure of $Bi_2O_2$($S_{0.5}Se_{0.5}$) consisting of mixed chalcogen nets. The thermoelectric power factor of $Bi_2O_2S_{0.5}Se_{0.5}$ is much greater than those of $Bi_2O_2S$ and $Bi_2O_2Se$, suggesting that introducing mixed chalcogen net in $Bi_2O_2Q$ is a possible way of enhancing the thermoelectric property of $Bi_2O_2Q$.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.10a
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• pp.784-786
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• 2010

Implementation possibility of inline dispersion management (DM) using bi-end schemes, which consist of one single mode fiber (SMF) and two dispersion compensating fiber (DCF) placed at front and rear of SMF, respectively, is investigated for compensating total dispersion accumulated in a span of WDM transmission links. It is confirmed that if net residual dispersion (NRD) is decided to be ${\pm}10\;ps/nm$ then bi-end scheme is effective to compensate for WDM channels with wide launching power range.

• Development and Reproduction
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• v.24 no.3
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• pp.225-230
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• 2020

This study reports the presence of mature and bi-sexual phase gonads in red spotted grouper, Epinephelus akaara after less than a year of cultivation in a commercial indoor tank and a net cage. In December 2018, juveniles were placed in an indoor tank and cultured for five months. In June 2019, the fish were transferred to a net cage and cultured until September. The rearing temperatures ranged from 19.86℃-24.65℃ in the indoor tank and 21.86℃-27.65℃ in the net cage. During the net cage culture period, specimens were randomly selected for histological gonad examination. The highest gonadosomatic index (GSI) value was measured in July (3.38±2.53), and dramatically decreased in August (0.44±0.21) and September (0.42±0.30). In July, some mature fish showed signs of vitellogenic stage oocyte development (vitellogenic and oil droplet stage oocytes), but immature fish were in an early developmental stage containing peri-nucleolus stage (PNS) oocytes. Bi-sexual phase gonads containing spermatocytes and spermatids were observed in the lumen and several PNS oocytes. By August and September, most specimens showed early-stage ovary development. However, mature testis (in August) and bi-sexual phase gonads (in September) were also observed. These results provide evidence for early puberty and hermaphroditism in the red spotted grouper.

• Journal of Advanced Navigation Technology
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• v.15 no.2
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• pp.248-255
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• 2011

An investigation has been carried out, by computer simulation, to evaluate the impact of dispersion compensation configurations on 960 Gbps wavelength division multiplexed (WDM) system with optical phase conjugator (OPC). The considered dispersion compensation configurations in this research are conventional one-end type and bi-end type. One-end and bi-end type are made by using one dispersion compensating fiber (DCF) and two DCFs to decrease dispersion accumulated in one single mode fiber (SMF) span, respectively. It is found that bi-end compensation configuration offers the equal performance with that of one-end configuration in WDM system with residual dispersion per span (RDPS) of 400 ps/nm if net residual dispersion (NRD) had to be optimized in each cases.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.05a
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• pp.676-677
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• 2022

In this paper, we propose a new method based on a deep learning model with an optimized dynamic decay learning rate and improved model structure to achieve fast and accurate classification of fashion clothing images. Experiments are performed using the model proposed in the Fashion-MNIST dataset and compared with methods of CNN, LeNet, LSTM and BiLSTM.

• The Journal of the Acoustical Society of Korea
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• v.42 no.5
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• pp.395-401
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• 2023

Sound Event Detection (SED) aims to identify not only sound category but also time interval for target sounds in an audio waveform. It is a critical technique in field of acoustic surveillance system and monitoring system. Recently, various models have introduced through Detection and Classification of Acoustic Scenes and Events (DCASE) Task 4. This paper explored how to design optimal parameters of DenseNet based model, which has led to outstanding performance in other recognition system. In experiment, DenseRNN as an SED model consists of DensNet-BC and bi-directional Gated Recurrent Units (GRU). This model is trained with Mean teacher model. With an event-based f-score, evaluation is performed depending on parameters, related to model architecture as well as model training, under the assessment protocol of DCASE task4. Experimental result shows that the performance goes up and has been saturated to near the best. Also, DenseRNN would be trained more effectively without dropout technique.

• Journal of Information Processing Systems
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• v.14 no.1
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• pp.150-161
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• 2018

We propose a novel deep neural network model for detecting human activities in untrimmed videos. The process of human activity detection in a video involves two steps: a step to extract features that are effective in recognizing human activities in a long untrimmed video, followed by a step to detect human activities from those extracted features. To extract the rich features from video segments that could express unique patterns for each activity, we employ two different convolutional neural network models, C3D and I-ResNet. For detecting human activities from the sequence of extracted feature vectors, we use BLSTM, a bi-directional recurrent neural network model. By conducting experiments with ActivityNet 200, a large-scale benchmark dataset, we show the high performance of the proposed DeepAct model.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.2
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• pp.291-299
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• 2002

This paper characterizes hi-directionally oscillating flow in planar microdiffusers in order to evaluate the frequency-dependent flow rectification performance of the microdiffusers. In the theoretical study, we analyze a hi-directionally oscillating flow in the planar microdiffuser. In the experimental study, we fabricate two different microdiffuser prototypes, having different neck widths of 100 ㎛ (D100) and 300 ㎛(D300), respectively. The experimental net flow rates are measured as 116.6 $\mu$ι/min. and 344.4 $\mu$ι/min. for D100 and D300, respectively. The experimental flow rate of D300 decreases at the oscillating flow frequencies higher than 90Hz, at which the net boundary layer thickness is reduced to the microdiffuser neck width. It is experimentally verified that the flow rectification performance and the net flow rate of the microdiffusers tend to decrease when the boundary layer thickness is smaller than the diffuser neck width.

• Nuclear Engineering and Technology
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• v.52 no.11
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• pp.2613-2619
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• 2020

This work investigated the gamma-ray shielding performance, and the physical and mechanical properties of poly (methyl methacrylate) (PMMA) composites embedded with 0-44.0 wt% bismuth trioxide (Bi₂O₃) fabricated by the fast ultraviolet (UV) curing method. The results showed that the addition of Bi₂O₃ had significantly improved the gamma shielding ability of PMMA composites. Mass attenuation coefficient and half-value layer were examined using five gamma sources (Cs-137, Ba-133, Cd-109, Co-57, and Co-60). The high loading of Bi₂O₃ in the PMMA samples improved the micro-hardness to nearly seven times that of the pure PMMA. With these enhancements, it was demonstrated that PMMA/Bi₂O₃ composites are promising gamma shielding materials. Furthermore, the fast UV curing exerts its great potential in significantly shortening the production cycle of shielding material to enable rapid manufacturing.