• Journal of Microbiology and Biotechnology
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• v.10 no.5
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• pp.656-662
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• 2000

A high level of Staphylococcus haemolyticus L62 lipase was expressed in an Escherichia coli transformant. The expressed lipase activity in the cell-free extract was 70,800 U/l, which corresponded to 30% of the total cellular protein. Pre-mixing of the l62 lipase with some nonionic detergents enhanced its hydrolytic activity towards olive oil: Tween detergents activated the L62 lipase by 3 fold. Gel filtration chromatography of the Tween-80-L62 lipase mixture demonstrated a polymerized complex (∼180 kDa) formed exclusively between Tween-80 and the L62 lipase. The lipase enzyme in the complex showed a higher specific activity towards most triacylglycerols than the intact L62 lipase. The activity enhancement towards each substrate was quite different depending on the acyl chain length; the activity towards tributyrin, trilinolein, and trilinolenin was much more enhanced than the towards the medium and the long-chain saturated triglycerides.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1992.05a
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• pp.105-109
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• 1992

ITO film, 1500${\AA}$ of thickness, onto glass and p-InP wafer was prepared by e-beam evaporator. The bet ITO film had the resistivity 5.3${\times}$10$\^$-3/ $\Omega$-cm, the concentration 6.5${\times}$10$\^$20/cm$\^$-3/, the transmittance above 80%, and the optical energy gap about 3.5eV. The higher pressure of injected oxygen, the less reverse bias saturation current and the more open circuit voltage. Under the optimum evaporation conditions, the efficiency was 7.19% and the series resistance, and the shunt resistance were respectively 8.5%, 3${\alpha}$, and 26K$\Omega$. The interdependence between activation energy and pre-exponential factor was found. We found he surface of the p-InP became n-type and consquently supposed that the buried homojunction formation, that is, n+-ITO/n-InP/p-InP was caused by Sn diffusion or loss of phosphorus in the interface layer.

• Proceedings of the Korea Information Processing Society Conference
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• 2014.04a
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• pp.992-994
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• 2014

Hemispheric asymmetry in prefrontal activation have been proposed in two decades ago, as measured by electroencephalographic (EEG) power in the theta band (4-8Hz), is related to reactivity to affectively pleasure audio stimuli. In this study, we designed an emotional audio stimulus experiment in order to verify frontal EEG asymmetry by analyzing ERSP results. Thirty healthy college students volunteered the stimulus experiment with the standard IADS affective sounds. These affective sound clips are classified in three emotion states, happy, neutral and fear. ERSP image results revealed that there are the stronger responses of high arousal (fear and happy) in the left prefrontal lobe, while the stronger responses of low arousal (neutral) in the right pre-frontal lobe. However, the high pleasure emotions (happy) can elicit greater relative right EEG activity, while the low and middle pleasure emotions (fear and neutral) can elicit the greater relative left EEG activity. Additionally, the most response differences of theta band have been found out in the medial frontal lobe, which is proved as the frontal midline theta.

• Transactions of the Society of Information Storage Systems
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• v.9 no.2
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• pp.42-47
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• 2013

In this study, we have experimentally analyzed how the surface properties of transparent electrode layer influence the photovoltaic performance of bulk heterojunction organic solar cell by the contact angle measurement and X-ray photoelectron spectroscopy(XPS) observation. As a result, the power conversion efficiency of test devices improved from 0.64% to 1.83% and 2.15% by UV-ozone exposure and $O_2$ plasma treatment, respectively. Thus, we conclude that the surface activation process is very important for better performance and stability in addition to the cleaning process of carbonate residue on the surface.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.68 no.1
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• pp.1-7
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• 2019

Due to the highly concentrated power plants integrated through the limited transmission lines in Korea, a Special Protection System(SPS) has been applied to stabilize the power systems by instantly tripping the pre-determined generators in a large-scaled power plant when a fault occurs on the drawing transmission lines. Moreover, power outputs of those generators are constrained to avoid any activation of Under Frequency Load Shedding(UFLS) even after those generators are tripped by SPS action. For this, this paper proposes a method for calculating the required capacity of Energy Storage System(ESS) expected to relieve the operating constraints to generators using its fast response for controlling power system frequency. The proposed method uses the generator acceleration energy to derive the stable condition during the SPS action. In addition, its effectiveness is verified by the case studies adopting actual SPS operations in Korean power systems.

• Smart Structures and Systems
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• v.24 no.3
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• pp.361-377
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• 2019

The stiffness of shape memory alloy (SMA) spring while in actuation is represented by an empirical model that is derived from the logistic differential equation. This model correlates the stiffness to the alloy temperature and the functionality of SMA spring as active variable stiffness actuator (VSA) is analyzed based on factors that are the input conditions (activation current, duty cycle and excitation frequency) and operating conditions (pre-stress and mechanical connection). The model parameters are estimated by adopting the nonlinear least square method, henceforth, the model is validated experimentally. The average correlation factor of 0.95 between the model response and experimental results validates the proposed model. In furtherance, the justification is augmented from the comparison with existing stiffness models (logistic curve model and polynomial model). The important distinction from several observations regarding the comparison of the model prediction with the experimental states that it is more superior, flexible and adaptable than the existing. The nature of stiffness variation in the SMA spring is assessed also from the Dynamic Mechanical Thermal Analysis (DMTA), which as well proves the proposal. This model advances the ability to use SMA integrated mechanism for enhanced variable stiffness actuation. The investigation proves that the stiffness of SMA spring may be altered under controlled conditions.

• The Korean Journal of Food And Nutrition
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• v.32 no.3
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• pp.246-250
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• 2019

Nelumbo nucifera Gaertn has been usedas a traditional remedy and food source in South Korea. It promotes gastrointestinal function and controls blood pressures. Nelumbo nucifera Gaertn water extracts supplement at 5, 10, 50, 100, 250, 500, $1,000{\mu}g/mL$ after a 48 h pre-treatment with the mitogen (ConA or LPS) increased the mouse splenocytes proliferation. Water extract supplement also increased the cytokine production ($IL-1{\beta}$, $TNF-{\alpha}$ and $IFN-{\gamma}$), measured by a cytokine ELISA kit. For the result of in vitro study, the proliferation of splenocytes and cytokine production activated by peritoneal macrophages increased when water extracts were supplemented in the range of $50{\sim}500{\mu}L/mL$ concentration. Specifically, the levels of the splenocytes proliferation, $IL-1{\beta}$, $TNF-{\alpha}$ and $IFN-{\gamma}$ were the highest at $250{\mu}L/mL$ concentration. This in vitro study suggestedthat supplementation with Nelumbo nucifera Gaertn water extracts may enhance the immune function by regulating the splenocyte proliferation and enhancing the cytokine production activating macrophage in vitro.

• Korean Journal of Food Science and Technology
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• v.51 no.5
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• pp.499-502
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• 2019

Poly(ADP-ribose) polymerase (PARP) is a nuclear enzyme which is activated in response to DNA damage, and which mediates DNA repair. PARP inhibitors can be used to reduce resistance of cancer cells to anticancer treatments. The objective of this study was to investigate the effects of selected phytochemicals and fruit extracts on PARP activation in MCF-7 breast cancer cells subjected to oxidative stress. Pre-incubation with epigallocatechin gallate (EGCG), apple extract (AE), cranberry extract (CE), or grape extract (GE) for 2 hours at test concentrations reduced PARP activity induced upon treatment with hydrogen peroxide in a dose-dependent manner (p<0.05). GE was found to be the most efficient PARP inhibitor among the fruit extracts examined. These results suggest that phytochemicals of fruit extracts might be used as PARP inhibitors in order to assist anticancer agents.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.1
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• pp.147-165
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• 2021

In this work, we empirically evaluated the efficiency of the recent EfficientNetB0 model to identify and diagnose malaria parasite infections in blood smears. The dataset used was collected and classified by relevant experts from the Lister Hill National Centre for Biomedical Communications (LHNCBC). We prepared our samples with minimal image transformations as opposed to others, as we focused more on the feature extraction capability of the EfficientNetB0 baseline model. We applied transfer learning to increase the initial feature sets and reduced the training time to train our model. We then fine-tuned it to work with our proposed layers and re-trained the entire model to learn from our prepared dataset. The highest overall accuracy attained from our evaluated results was 94.70% from fifty epochs and followed by 94.68% within just ten. Additional visualization and analysis using the Gradient-weighted Class Activation Mapping (Grad-CAM) algorithm visualized how effectively our fine-tuned EfficientNetB0 detected infections better than other recent state-of-the-art DCNN models. This study, therefore, concludes that when fine-tuned, the recent EfficientNetB0 will generate highly accurate deep learning solutions for the identification of malaria parasites in blood smears without the need for stringent pre-processing, optimization, or data augmentation of images.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.4
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• pp.1275-1292
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• 2021

As a fine-grained classification problem, aspect-level sentiment classification predicts the sentiment polarity for different aspects in context. To address this issue, researchers have widely used attention mechanisms to abstract the relationship between context and aspects. Still, it is difficult to effectively obtain a more profound semantic representation, and the strong correlation between local context features and the aspect-based sentiment is rarely considered. In this paper, a hybrid attention capsule network for aspect-level sentiment classification (ABASCap) was proposed. In this model, the multi-head self-attention was improved, and a context mask mechanism based on adjustable context window was proposed, so as to effectively obtain the internal association between aspects and context. Moreover, the dynamic routing algorithm and activation function in capsule network were optimized to meet the task requirements. Finally, sufficient experiments were conducted on three benchmark datasets in different domains. Compared with other baseline models, ABASCap achieved better classification results, and outperformed the state-of-the-art methods in this task after incorporating pre-training BERT.