• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.8
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• pp.1015-1021
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• 2020

Mobile news users want news articles without advertising, meanwhile the news providers require advertisement displays in several types to attain advertising revenue. In this paper, we classified the types of advertisements on mobile news articles into fixed article type which is fixed on some areas of articles, fixed screen type which is fixed on mobile screens, and a combination type of them. In addition, we proposed a smart solution based on overlapping method which effectively organize advertisements to not distract the readers. The proposed method is similar to fixed article type and overlapping technique of advertisements on news article's photo or virtual area. The performance evaluation result shows that the proposed method provides more spaces for news articles effectively than the existing methods. Although only some areas of advertisements may be blocked according to the number or size of advertisements, the effect is not critical.

• Journal of Ocean Engineering and Technology
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• v.35 no.3
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• pp.173-182
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• 2021

The maneuvering performance of a ship on the actual sea is very different from that in calm water due to wave-induced motion. Enhancement of a ship's maneuverability in waves at the design stage is an important way to ensure that the ship navigates safely. This paper focuses on the maneuvering prediction of a Russian trawler in wind and irregular waves. First, a unified seakeeping and maneuvering analysis of a Russian trawler is proposed. The hydrodynamic forces acting on the hull in calm water were estimated using empirical formulas based on a database containing information on several fishing vessels. A simulation of the standard maneuvering of the Russian trawler was conducted in calm water, which was checked using the International Maritime Organization (IMO) standards for ship maneuvering. Second, a unified model of seakeeping and maneuvering that considers the effect of wind and waves is proposed. The wave forces were estimated by a three-dimensional (3D) panel program (ANSYS-AQWA) and used as a database when simulating the ship maneuvering in wind and irregular waves. The wind forces and moments acting on the Russian trawler are estimated using empirical formulas based on a database of wind-tunnel test results. Third, standard maneuvering of a Russian trawler was conducted in various directions under wind and irregular wave conditions. Finally, the influence of wind and wave directions on the drifting distance and drifting angle of the ship as it turns in a circle was found. North wind has a dominant influence on the turning trajectory of the trawler.

• Journal of Positioning, Navigation, and Timing
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• v.10 no.1
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• pp.13-20
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• 2021

A series of numerical experiments with measurements observed at continuously operating reference stations (CORS) of the international GNSS services (IGS) and the national geographical information institute of Korea (NGII) have been intensively carried out to evaluate the quality of pseudo-ranges and carrier-phases of GPS L2C signal obtained by various receiver types, benign and harsh operational environment. In this analysis, some quality measures, such as signal-to-noise ratio (SNR), the magnitude of multipath, and the number of cycle slips, the pseudo-range and carrier phase obtaining rate were computed and compared. The SNR analysis revealed an impressive result that the trend in the SNR of C/A and the L2C comparably depends upon type of receivers. The result of multipath analysis also showed clearly different tendency depending on the receiver types. The reason for this inconsistent tendency was seemed to be that the different multipath mitigation algorithm built-in each receiver. The number of L2C cycle slip was less than P2(Y), and L2C measurements obtaining rate was higher than that of P2(Y) in three receiver types. In the harsh observational environment, L2C quality was not only superior to P2(Y) in all aspects such as SNR, multipath magnitude, the number of cycle slips, and measurement obtaining rate, but also it could maintain a level of quality equivalent to C/A. According to the results of this analysis, it's expected that improved positioning performance like accuracy and continuity can be got through the use of L2C instead of existing P2(Y).

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.6
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• pp.33-43
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• 2021

A60 class bulkhead penetration piece is a fire resistance system installed on a bulkhead compartment to protect lives and to prevent flame diffusion in a fire accident on a ship and offshore plant. This study focuses on the approximate optimization of the fire resistance design of the A60 class bulkhead penetration piece using a multi-island genetic algorithm. Transient heat transfer analysis was performed to evaluate the fire resistance design of the A60 class bulkhead penetration piece. For approximate optimization, the bulkhead penetration piece length, diameter, material type, and insulation density were considered discrete design variables; moreover, temperature, cost, and productivity were considered constraint functions. The approximate optimum design problem based on the meta-model was formulated by determining the discrete design variables by minimizing the weight of the A60 class bulkhead penetration piece subject to the constraint functions. The meta-models used for the approximate optimization were the Kriging model, response surface method, and radial basis function-based neural network. The results from the approximate optimization were compared to the actual results of the analysis to determine approximate accuracy. We conclude that the radial basis function-based neural network among the meta-models used in the approximate optimization generates the most accurate optimum design results for the fire resistance design of the A60 class bulkhead penetration piece.

• International Journal of Industrial Entomology and Biomaterials
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• v.44 no.2
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• pp.65-71
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• 2022

The wild silkmoth Antheraea yamamai Guérin-Méneville, 1861 (Lepidoptera: Saturniidae) is an important producer of silk that is superior to the silk produced by traditional domesticated silkworm. In this study, we sequenced the complete mitochondrial genome (mitogenome) of An. yamamai collected from Jeju Island, which is the southernmost island approximately 100 km offshore southward from the Korean Peninsula. Determining this sequence will be necessary for tracing the biogeographic history of the species and developing molecular markers for identifying the origin of commercial products. Comparison of the sequence divergence among two available and the current mitogenomes revealed a low but substantial number of substitutions, totaling 23 nucleotides in the whole genome. CytB and ND5 showed the highest variability with five and four variations, respectively, suggesting that these regions will be prior regions to target for subsequent biogeographic and diagnosis study. Phylogenetic reconstruction based on all available sequences of Saturniidae showed that An. yamamai is a sister to the congeneric species An. pernyi, corroborating that Antheraea is a highly supported monophyletic group. The tribe Saturniini was clearly non-monophyletic and interrupted by Attacini and Bunaeini.

• Structural Engineering and Mechanics
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• v.81 no.5
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• pp.565-574
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• 2022

The infrastructures such as offshore, bridges, power plant, oil and gas piping and aircraft operate in a harsh environment during their service life. Structural integrity of engineering components used in these industries is paramount for the reliability and economics of operation. Two regression models based on the concept of Gaussian process regression (GPR) and Minimax probability machine regression (MPMR) were developed to predict stress intensity factor range (𝚫K). Both GPR and MPMR are in the frame work of probability distribution. Models were developed by using the fatigue crack growth data in MATLAB by appropriately modifying the tools. Fatigue crack growth experiments were carried out on Eccentrically-loaded Single Edge notch Tension (ESE(T)) specimens made of API 5L X65 Grade steel in inert and corrosive environments (2.0% and 3.5% NaCl). The experiments were carried out under constant amplitude cyclic loading with a stress ratio of 0.1 and 5.0 Hz frequency (inert environment), 0.5 Hz frequency (corrosive environment). Crack growth rate (da/dN) and stress intensity factor range (𝚫K) values were evaluated at incremental values of loading cycle and crack length. About 70 to 75% of the data has been used for training and the remaining for validation of the models. It is observed that the predicted SIF range is in good agreement with the corresponding experimental observations. Further, the performance of the models was assessed with several statistical parameters, namely, Root Mean Square Error (RMSE), Mean Absolute Error (MAE), Coefficient of Efficiency (E), Root Mean Square Error to Observation's Standard Deviation Ratio (RSR), Normalized Mean Bias Error (NMBE), Performance Index (ρ) and Variance Account Factor (VAF).

• Journal of Sensor Science and Technology
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• v.31 no.2
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• pp.90-95
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• 2022

The effect of the structure of an ITO nanoparticle film sensor on its performance was studied. A printed ITO film (P-ITO film) was fabricated on a flexible polyethylene terephthalate (PET) substrate, and the contact resistance of the electrode and sensor response change were clarified according to the detection position. The contact resistance between Ag and P-ITO was observed to be -204.4 Ω using the transmission line method (TLM), confirming that a very good ohmic contact is possible. In addition, we confirmed that the contact position of the analyte had a significant influence on the response of the sensor. Based on these results, the performance of the four types of sensors was compared. Consequently, we observed that 1) optimizing the resistance of the printed film, 2) optimizing the electrode structure and analyte input position, and 3) optimizing the electrode area are very important for fabricating a metal oxide nanoparticle (MONP) sensor with optimal performance.

• Journal of Sensor Science and Technology
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• v.31 no.2
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• pp.85-89
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• 2022

We investigated a pH sensor using an Indium tin oxide (ITO) nanoparticle (NP) film printed on a flexible substrate. First, the printing precision and mechanical stability of the ITO-printed film were investigated. In particular, the factors that influence the crystallinity of ITO films were studied using X-ray diffraction pattern analysis. The response of the ITO pH sensor was calibrated using a series of standard pH solutions (pH 3-11). The pH values of various specimens were measured using an ITO pH sensor, and the results were compared with those of various pH measurement methods. As a result of the experiment, the maximum error was approximately ± 0.04 pH (0.4 %) at pH 9, which indicated that the ITO pH sensor is highly suitable for pH measurement. Finally, we used the ITO pH sensor to the measure of general specimens such as solvents and beverages and compared the results in comparison with those obtained from several conventional methods.

• Progress in Superconductivity and Cryogenics
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• v.12 no.4
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• pp.24-30
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• 2010

The renewable energy source is considered as a good measure to cope with the global warming problem and the fossil energy exhaustion. The construction of electric power plant such as an offshore wind farm is rapidly increasing and this trend is expected to be continued during this century. The bulky and long distance power transmission media is essential to support and promote the sustainable expansion of renewable energy source. DC power cable is generally considered as the best solution and the demand for DC electric power has been rapidly increasing. Especially, the high temperature superconducting (HTS) DC cable system begins to make a mark because of its advantages of huge power transmission capacity, low transmission loss and other environmental friendly aspects. Technical contents of DC HTS cable system are very similar to those of AC HTS cable system. However the DC HTS cable can be operated near its critical current if the heat generation is insignificant, while the operating current of AC HTS cable is generally selected at about 50~70% of the critical current because of AC loss. We chose the specifications of the cable core of 'Tres Amigas' project as an example for our study and investigated the heat generation when the DC HTS cable operated near the critical current by some electric and thermal analyses. In this paper, we listed some technical issues on the design of the DC HTS cable core and described the process of the cable core design. And the results of examination on the current capacity, heat generation, harmonic loss and current distribution properties of the DC HTS cable are introduced.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.05a
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• pp.589-591
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• 2021

In the offshore plant industry, the Access service basket for aerial work is used of for various business purposes. However, various types of safety accidents continue to occur in operating these system. In the case of high-capacity workstations currently in use, workers are exposed to various risks in determining and operating the load capacity, proximity distance, and direction of operation. In this paper, to solve this problem, we develop a device that incorporates IoT-based monitoring and crash alarm systems into aerial work systems. The developed device was tested in the presence of experts to ensure reliability of the device, which allows workers and managers to easily check the operation status and thereby prevent safety accidents in advance.