• The Journal of Engineering Geology
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• v.33 no.4
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• pp.673-687
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• 2023

Exploratory data analysis is the process of observing and understanding data collected from various sources to identify their distributions and correlations through their structures and characterization. This process can be used to identify correlations among conditioning factors and select the most effective factors for analysis. This can help the assessment of landslide susceptibility, because landslides are usually triggered by multiple factors, and the impacts of these factors vary by region. This study compared two stages of exploratory data analysis to examine the impact of the data exploration procedure on the landslide prediction model's performance with respect to factor selection. Deep-learning-based landslide susceptibility analysis used either a combinations of selected factors or all 23 factors. During the data exploration phase, we used a Pearson correlation coefficient heat map and a histogram of random forest feature importance. We then assessed the accuracy of our deep-learning-based analysis of landslide susceptibility using a confusion matrix. Finally, a landslide susceptibility map was generated using the landslide susceptibility index derived from the proposed analysis. The analysis revealed that using all 23 factors resulted in low accuracy (55.90%), but using the 13 factors selected in one step of exploration improved the accuracy to 81.25%. This was further improved to 92.80% using only the nine conditioning factors selected during both steps of the data exploration. Therefore, exploratory data analysis selected the conditioning factors most suitable for landslide susceptibility analysis and thereby improving the performance of the analysis.

• Phonetics and Speech Sciences
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• v.15 no.4
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• pp.91-100
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• 2023

Reverberation time (T60) is a typical acoustic parameter that provides information about reverberation. Since the impacts of reverberation vary depending on the frequency bands even in the same space, frequency-dependent (FD) T60, which offers detailed insights into the acoustic environments, can be useful. However, most conventional blind T60 estimation methods, which estimate the T60 from speech signals, focus on fullband T60 estimation, and a few blind FDT60 estimation methods commonly show poor performance in the low-frequency bands. This paper introduces a modified approach based on Attentive pooling based Weighted Sum of Spectral Decay Rates (AWSSDR), previously proposed for blind T60 estimation, by extending its target from fullband T60 to FDT60. The experimental results show that the proposed method outperforms conventional blind FDT60 estimation methods on the acoustic characterization of environments (ACE) challenge evaluation dataset. Notably, it consistently exhibits excellent estimation performance in all frequency bands. This demonstrates that the mechanism of the AWSSDR method is valuable for blind FDT60 estimation because it reflects the FD variations in the impact of reverberation, aggregating information about FDT60 from the speech signal by processing the spectral decay rates associated with the physical properties of reverberation in each frequency band.

• Korean Chemical Engineering Research
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• v.62 no.3
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• pp.238-245
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• 2024

The lactate electrode can be utilized either as an electrode for lactate sensor to monitor the patient's health status, stress level, and athlete's fatigue in real time or lactate fuel cell. In this study, we fabricated a high-performance electrode composed of lactate oxidase, catalase, and mitochondria, and investigated the surface analysis and electrochemical properties of this electrode. Carbon paper modified with single-walled carbon nanotubes (CP-SWCNT) had significantly improved electrical conductivity compared to before modification. The electrode to which lactate oxidase, catalase, and mitochondria were attached (CP-SWCNT-LOx-Cat-Mito) produced a higher current than the electrode to which lactate oxidase and catalase were attached. The amount of reduction current produced by the bilirubin oxidase (BOD)-attached electrode (CP-SWCNT-BOD) was greatly affected by the presence or absence of oxygen in the electrolyte. The fuel cell composed of CP-SWCNT-LOx-Cat-Mito (anode) and CP-SWCNT-BOD (cathode) produced maximum power (29 ㎼/cm²) at a discharge current density of 133 ㎂/cm². From this study, we had proved that mitochondria is essential for improving lactate sensor and fuel cell performance.

• The Journal of the Acoustical Society of Korea
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• v.43 no.5
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• pp.557-569
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• 2024

Recently, the operating speed of pressure devices is increased for high performance. It lead to the increase of flow rate. Consequently, the results in the high relative contribution of flow borne noise to the noise from pipe. Analyzing the characteristics of flow-borne noise is essential for evaluating noise performance during the design stage of the piping system. Therefore, in this paper, the noise generation mechanism and transfer characteristic was numerically investigated. The wall pressure induced by the fluid moving through the orifice was predicted using the compressible Large Eddy Simulation (LES). The Wavenumber-Frequency Analysis (WFA) was employed to decompose the wall pressure into incompressible and compressible component, which are to cause Fluid Induced Vibration (FIV) and Acoustic Induced Vibration (AIV). The propagation and contribution characteristics were analyzed using the separated incompressible and compressible wall pressure components. Additionally, the correlation between these pressure components and the internal flow within the piping was investigated through flow field analysis, which elucidated the mechanisms and propagation characteristics of flow-induced noise. From these results, it was confirmed that the contribution of the incompressible wall pressure component was high near the noise source and that the contribution of the compressible wall pressure component increased as it propagated long distances upstream and downstream direction of the noise source.

• Journal of Surface Science and Engineering
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• v.57 no.5
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• pp.425-431
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• 2024

As demand in the electric vehicle market increases, the development of high capacity, high energy density lithium-ion batteries (LIBs) is required. Silicon has a extremely high theoretical capacity of 4200 mAh/g, but low cycle life and structural instability due to high volume expansion during charging and discharging are critical issue to solve. A reduced silicon oxide has also a high theoretical capacity of 2500 mAh/g and recently studied extensively for its low-cost, superior cycle life, and structural stability. In this study, we first synstheized SiO₂ particles by sol-gel method using tetraethyl orthosilicate (TEOS) precursor. The SiO₂ particle size was controlled with an average particle size of 300-600 nm by the addition amount of TEOS, NH₃, and H₂O. The synthesized SiO₂ particles were reduced to SiO_x through the magnesiothermic reduction reaction (MRR), and electrochemical characteristics were evaluated according to the particle size of SiO_x. For electrochemical characterization, SiO_x (10 wt.%) was mixed with graphite, and 2032 half cells were fabricated to obtain charge-discharge curve, cycle performance, rate performance, and electrochemical impedance spectroscopy curves. As a result, the mean size of SiO_x particle decreases from 600 to 300 nm, the initial discharge capacity increases from 459.9 to 556.5 mAh/g with the single capacity from 1359.4 to 2325.3 mAh/g, respectively. Finally, the present result shows the availability of MRR process to obtain reduced silicon oxide particles and sized dependent electrochemical properties to develop high capacity and high energy density LIBs.

• Journal of the Korean Electrochemical Society
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• v.4 no.2
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• pp.58-64
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• 2001

YSZ ($8mol\%$ yttria-stabilized zirconia)-modified LSM $(La_{0.85}Sr_{0.15}MnO_3)$ composite cathodes were fabricated by formation of YSZ film on triple phase boundary (TPB) of LSM/YSZ/gas. The YSZ coating film greatly enlarged electrochemical reaction sites from the increase of additional TPB. The composite cathode was formed on thin YSZ electrolyte (about 30 Um thickness) supported on an anode and then I-V characterization and AC impedance analyses were performed at temperature between $700^{\circ}C\;and\;800^{\circ}C$. As results of the impedance analysis on the cell at $800^{\circ}C$ with humidified hydrogen as the fuel and air as the oxidant, R1 around the frequency of 1000 Hz represents the anode Polarization. R2 around the frequency of 100Hz indicates the cathode polarization, and R3 below the frequency of 10 Hz is the resistance of gas phase diffusion through the anode. The cell with the composite cathode produced power density of $0.55\;W/cm^2\;and\;1W/cm^2$ at air and oxygen atmosphere, respectively. The I-V curve could be divided into two parts showing distinctive behavior. At low current density region (part I) the performance decreased steeply and at high current density region (part II) the performance decreased gradually. At the part I the performance decrease was especially resulted from the large cathode polarization, while at the part H the performance decrease related to the electrolyte polarization.

• Korean Chemical Engineering Research
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• v.50 no.2
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• pp.229-237
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• 2012

Phosphorus was incorporated into Co/$Al_2O_3$ catalyst for FTS by impregnating an acidic precursor, phosphoric acid, in ${\gamma}-Al_2O_3$ support to improve the mechanical strength, the hydrothermal stability of the catalyst particle, and the catalytic performance as well. Surface characterization techniques such as FT-IR revealed that $AlPO_4$ phase was generated on the surface of the P-modified catalyst. The addition of phosphorus was found to alleviate the interaction between cobalt and alumina surface, and to increase reducibility of catalyst. The catalytic activity such as $C_{5+}$ productivity and turnover frequency (TOF) was calculated to evaluate catalytic performance. The influence of calcination temperature of the $Al_2O_3$ containing 2 wt.% P on the catalytic performance was also investigated. Through hydrothermal stability test and XRD analysis, the P-modified catalyst had strong resistant to the pressurized and hot $H_2O$. The mechanical strength of the P-modified catalyst was also examined through an in-house fluidized-bed vessel, and it was found that the catalyst fragmentation could be successfully suppressed with P. Taken as a whole, the best performance was shown to be at 1~2 wt.% P in alumina and at the calcination temperature of $500^{\circ}C$.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.47 no.5
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• pp.50-60
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• 2010

For the last half a century, the personal computer and software industries have been prosperous due to the incessant evolution of computer systems. In the 21st century, the embedded system market has greatly increased as the market shifted to the mobile gadget field. While a lot of multimedia gadgets such as mobile phone, navigation system, PMP, etc. are pouring into the market, most industrial control systems still rely on 8-bit micro-controllers and simple application software techniques. Unfortunately, the technological barrier which requires additional investment and higher quality manpower to overcome, and the business risks which come from the uncertainty of the market growth and the competitiveness of the resulting products have prevented the companies in the industry from taking advantage of such fancy technologies. However, high performance, low-power and low-cost hardware and software platforms will enable their high-technology products to be developed and recognized by potential clients in the future. This paper presents such a platform for industrial embedded systems. The platform was designed based on Telechips TCC8300 multimedia processor which embedded a variety of parallel hardware for the implementation of multimedia functions. And open-source Embedded Linux, TinyX and GTK+ are used for implementation of GUI to minimize technology costs. In order to estimate the expected performance and power consumption, the performance improvement and the power consumption due to each of enabled hardware sub-systems including YUV2RGB frame converter are measured. An analytic model was devised to check the feasibility of a new application and trade off its performance and power consumption. The validity of the model has been confirmed by implementing a real target system. The cost can be further mitigated by using the hardware parts which are being used for mass production products mostly in the cell-phone market.

• Progress in Medical Physics
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• v.20 no.4
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• pp.235-243
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• 2009

The purpose of this experiment is to know the relation of the detection and characterization of liver's diseases as comparison of finding at MR imaging using a Ferucarbotran (SPIO) and Gd-EOB-DTPA (Primovist) agents in diffuse liver disease. A total of 50 patients (25 men and 25 women, mean age: 50 years) with liver diseases were investigated at 3.0T machine (GE, General Electric Medical System, Excite HD) "with 8 Ch body coil for comparison of diseases and contrast's uptake relation, which used the LAVA, MGRE." All images were performed on the same location with before and after Ferucarbotran and Gd-EOB-DTPA administrations (p<0.05). Contrast to noise ratio of Ferucarbotran and Gd-EOB-DTPA in the HCC were $3.08{\pm}0.12$ and $7.00{\pm}0.27$ with MGRE and LAVA pulse sequence, $3.62{\pm}0.13$ and $2.60{\pm}0.23$ in the hyper-plastic nodule, $1.70{\pm}0.09$ and $2.60{\pm}0.23$ in the meta, $2.12{\pm}0.28$ and $5.86{\pm}0.28$ in the FNH, $4.45{\pm}0.28$ and $1.73{\pm}0.02$ in the abscess and ANOVA test was used to evaluate the diagnostic performance of each disease (p<0.05). In conclusions, two techniques were well demonstrated with the relation of the detection and characterization of liver's diseases.

• Journal of Legislation Research
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• no.44
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• pp.487-538
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• 2013

It is the most critical issue in recent international intellectual property licence disputes to decide the applicable laws to the license contracts. As Korea and the European Union(EU) reached free trade agreement(FTA), and the EU-Korea FTA entered into force on July 1, 2011, the FTA has boosted social, economic, cultural exchanges between the two. As a result of the increased transactions in those sectors, legal disputes are also expected to grow. This situation calls for extensive research and understanding of the choice of law principles applicable to international intellectual property license contracts in the EU. To decide the laws applicable to issues arising from international intellectual property license contracts disputes, the characterization of those issues is necessary for the purpose of applying private international law principles to them. In terms of characterization, intellectual property license contracts fall within contractual matters. In the EU, the primary rule of choice of law principles in contractual obligations is the Rome I Regulation. Because the choice of law rules, such as private international law principles, the Rome Convention(1980), and the Rome I Regulation, differ in the time of application, it is essential to clarify the time factor of related contracts. For example, the Rome I Regulation applies to contracts which were concluded as from December 17, 2009. Although party autonomy in international contracts disputes is generally allowed, if there is no choice of law agreement between the parties to the contracts, the objective test rule of private international law doctrine could be the best option. Following this doctrine, the Rome I Regulation Article 4, Paragraph 1 provides the governing law rules based on the types of contracts, but there is no room for intellectual property license contracts. After all, as the rule for governing law of those contracts, the Rome I Regulation Article 4, Paragraph 2 should be applied and if there are countries which are more closely connected to the contracts under the Rome I Regulation Article 4, Paragraph 3, the laws of those countries become the governing laws of the contracts. Nevertheless, if it is not possible to decide the applicable laws to the license contracts, the Rome I Regulation Article 4, Paragraph 4 should be applied in the last resort and the laws of the countries which are the most closely connected to the contracts govern the license contracts. Therefore, this research on the laws applicable to intellectual property license contracts under the Rome I Regulation suggests more systematic and effective solutions for future disputes in which Korea and the EU countries play the significant role as the connecting factors in the conflict of laws rules. Moreover, it helps to establish comprehensive and theoretical understanding of applying the Korean Private International Law to multifarious choice-of-law cases.