• Journal of Adhesion and Interface
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• v.24 no.4
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• pp.124-130
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• 2023

For automotive coating agents that require little change in characteristics due to changes in external temperature, changes in noise characteristics due to changes in the external environment are very important. Therefore, soft polyurethane with excellent cold resistance, weather resistance, and abrasion resistance, and polysiloxane whose -OH terminated and side chains are modified with amines, are widely used. In this study, coating agents was prepared by adding water-born polyurethane, polysiloxane, ultra high molecular weight polypropylene (UHMWPP) powder, carbon black, and a matting agent to determine the effect of each resin component on noise. To study the effect of each resin component on noise, a coating agent was prepared by adding water-born polyurethane, polysiloxane, UHMWPP powder, carbon black, and a matting agent. The hard/soft segment ratio of water-born polyurethane, the main component of the coating, was 27.1%/72.9%, and the ratio of amino siloxanes to hydroxy-terminated polysiloxane was 2:7, which produced the least noise. The difference in friction coefficient was large when the friction body moves at high speed. When UHMWPP powder replaced SiO₂, noise decreased and gloss also decreased.

• Journal of the Korean Institute of Gas
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• v.27 no.4
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• pp.85-91
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• 2023

In this study, an experimental study was conducted on the flame behavior, combustion dynamics, and NOx emission characteristics for hydrogen co-firing with the EV burner which is the first stage combustor of GT24. It was confirmed that as the hydrogen co-firing rate increases, the NOx emission increases. This change was elucidate to be the result of a combination of changes in penetration depth due to changes in fuel density, reduction in fuel mixing due to changes in flame position due to increased flame propagation speed, and oscillation of fuel mixedness due to combustion instability. Through pressurization tests in the range of 1.3 to 3.1 bar, NOx emission characteristics under high-pressure operating conditions were predicted, and based on this, the hydrogen co-firing limits of the EV burner was evaluated.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.11 no.2
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• pp.37-48
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• 2006

HF radar-derived current data obtained in 2002 and 2004 are analyzed to examine the effects of the completion of the Saemangeum 4th tidal dyke in June 2003, connecting Gogunsan-Gundo and Bieung-Do, on the coastal surface $M_2$ current pattern. Comparison between the currents by HF radar and current meter mooring showed good agreements. Counterclockwise rotation of the $M_2$ current in the observed area did not change with the dyke construction. Strong westward ebb jet from the gap of the dyke was observed in 2002 but disappeared in 2004. The complete closing of the dyke gap caused the current speed increase around the mouth of the Kem River estuary, decrease around Gogunsan-Gundo and the dyke, the changes in the direction of maximum current to north-ward from eastward and the delay of the maximum flood current occurrence around Gogunsan-Gundo and the dyke. Around Yeon-Do, the maximum flood current directed more clockwise and occurred rather earlier. These changes of the $M_2$ current ellipse characteristics imply that the effects of the dyke construction reached the area connecting Mal-Do and Yeun-Do.

• Journal of Korea Society of Industrial Information Systems
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• v.29 no.2
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• pp.27-33
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• 2024

In this paper, the effects of separation distance from a thick radar cover on the performance of 24 GHz band radar was studied through experiments. When a polycarbonate radar cover with a thickness of 10 mm was placed in front of the radar, the variations in radar performance according to the change in the separation distance between the radar and the radar cover was compared with the case without the radar cover. As a radar performance indicator, the distance measured from the radar was used, and the distance was measured using the radar when a person moves away from the radar at a constant speed in the hallway of the building and then approaches again. The separation distance between the radar and radar cover was tested at 2 mm, 5 mm, and 20 mm, respectively. When there was no radar cover, the distance could be measured up to 49.64 m and the error was the lowest. When the separation distance was 2 mm, there was a section where distance measurement was not possible starting from 37.61 m, so the performance was the worst. When the separation distance was increased to 5 mm and 20 mm, the distance was measured up to 49.56 m, but the section where the error between the measured distance and the expected distance was large occurred more often than when there was no radar cover.

• The Journal of the Acoustical Society of Korea
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• v.26 no.4
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• pp.159-165
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• 2007

In this paper, we propose a new pre-selection of candidate units that is suitable for the unit selection based Japanese TTS system. General pre-selection method performed by calculating a context-dependent cost within IP (Intonation Phrase). Different from other languages, however. Japanese has an accent represented as the height of a relative pitch, and several words form a single accentual phrase. Also. the prosody in Japanese changes in accentual phrase units. By reflecting such prosodic change in pre-selection. the qualify of synthesized speech can be improved. Furthermore, by calculating a context-dependent cost within accentual phrase, synthesis speed can be improved than calculating within intonation phrase. The proposed method defines AP. analyzes AP in context and performs pre-selection using accentual phrase matching which calculates CCL (connected context length) of the Phoneme's candidates that should be synthesized in each accentual phrase. The baseline system used in the proposed method is VoiceText, which is a synthesizer of Voiceware. Evaluations were made on perceptual error (intonation error, concatenation mismatch error) and synthesis time. Experimental result showed that the proposed method improved the qualify of synthesized speech. as well as shortened the synthesis time.

• Journal of the Korean Society of Marine Environment & Safety
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• v.30 no.1
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• pp.118-126
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• 2024

In this paper, the research contents and results related to the automation of the hull-form optimal design of container ships are summarized. A container ship is a ship that generally operates near Froude number of 0.26. To implement hull-form optimal design automation for ships operating at this speed, an optimization algorithm, a hull-form change algorithm, a ship performance prediction algorithm, an automation algorithm, and an iterative calculation technique were applied to develop a numerical analysis computer program that enables hull-form optimal design automation of the container ship, and it was named HOTCONTAINER. In this study, a sensitivity analysis algorithm was developed and applied to appropriately set design variables for hull-form optimal design. To understand the reliability and real ship applicability of the developed algorithm, a numerical analysis was performed on KCS(KRISO Container Ship), a container ship that has been studied in various ways worldwide. Consequently, the optimal ship was derived, and the wave resistance, wave pattern, and wave height of the target and optimal ship were compared. In conclusion, compared the target ship, the optimal ship a 47.63% decrease in wave resistance, and the displacement and wet surface area decreased by 0.50% and 0.39%, respectively.

• Journal of Nutrition and Health
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• v.57 no.1
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• pp.27-42
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• 2024

Purpose: This study examined whether regular moderate-intensity treadmill exercise (Ex) and Syzygium aromaticum L. (SA) administration can influence lipid and muscle metabolism in obese rats induced by a 60% high-fat diet (HFD). Methods: Rats, except those in the Normal group, were exposed to a 60% HFD for 4 weeks to induce obesity. The obese rats were assigned randomly to three groups: HFD control group, HFD+Ex group, and HFD+Ex+SA group. Treadmill exercise was conducted five times a week for 4 weeks, with a 5° incline and a speed of 18 m/min (Week 1: 20 minutes; Weeks 2: 25 minutes; Weeks 3-4: 30 minutes). Serum analysis was performed. Western blot analysis was conducted on the liver and soleus muscle, and histopathological analysis was carried out on the liver and adipose tissues. Results: The body weight change in the Ex groups was significantly lower than in the HFD control group, while the soleus muscle weight in the HFD+Ex group increased significantly. The histopathological examination in the Ex groups revealed a marked reduction in liver lipid accumulation and a decrease in adipocyte size in adipose tissue. Obesity induction increased leptin levels substantially, but Ex notably reversed these changes. Ex resulted in significant inhibition of ROS and ONOO^-, whereas the serum inflammatory cytokine, IL-1β, and total cholesterol were reduced only by SA administration. Furthermore, the inflammatory proteins in the liver were inhibited more effectively when Ex was supplemented with SA. The expression of the muscle synthesis-related proteins and degradation proteins were modulated by Ex and Ex+SA. Conclusion: Ex significantly affected lipid and muscle metabolism, and adding SA alleviated the inflammation.

• Journal of Navigation and Port Research
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• v.48 no.4
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• pp.249-260
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• 2024

This paper aimed to summarize research on technologies that could efficiently reduce wave-making resistance of container ships. Tto develop wave resistance reduction technology that could be applied to container ships and use it in real ship design, hull-form optimal design was performed by applying optimization algorithms, hull-form change algorithms, ship performance prediction algorithms, automation algorithms, and iterative optimal design techniques. A computer program was also developed. To properly set design variables known to be important elements in hull-form optimal design and to efficiently set lower and upper limits of design variables, a sensitivity analysis algorithm was developed and applied to hull-form optimal design. To predict the reliability and applicability of the developed computer program for real ships, hull-form optimal design was performed for a KRISO Container Ship (KCS), a container ship with various studies conducted worldwide. Hull-form optimal design was performed at Fn=0.26, the design speed of the KCS ship. Numerical analysis was performed on the hull-form of the target ship, the KCS ship, and the hull-form of the ship derived as a result of the hull-form optimal design to determine wave resistance, wave system, and wave height. The optimal ship's wave resistance was found to be reduced by 80.60% compared to the target ship. The displacement and wetted surface area were also found to be reduced by 1.54% and 1.21%, respectively.

• The Korean Journal of Applied Statistics
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• v.37 no.4
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• pp.525-539
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• 2024

Massive multiplayer online role playing game (MMORPG) is a common type of game these days. Predicting user churn in MMORPG is a crucial task. The retention rate of users is deeply associated with the lifespan and revenue of the service. If the churn of a specific user can be predicted in advance, targeted promotions can be used to encourage their stay. Therefore, not only the accuracy of churn prediction but also the speed at which signs of churn can be detected is important. In this paper, we propose methods to identify early signs of churn by utilizing the daily predicted user retention probabilities. We train various deep learning and machine learning models using log data and estimate user retention probabilities. By analyzing the change patterns in these probabilities, we provide empirical rules for early identification of users at high risk of churn. Performance evaluations confirm that our methodology is more effective at detecting high risk users than existing methods based on login days. Finally, we suggest novel methods for customized marketing strategies. For this purpose, we provide guidelines of the percentage of accessed users who are at risk of churn.

• International conference on construction engineering and project management
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• 2024.07a
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• pp.1295-1295
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• 2024

As extreme weather events such as heavy snowfall and typhoon become more frequent, climate change significantly impacts across various worldwide industries. With demands for dealing with this phenomenon, continuous achievements in safety diagnosis have been announced for large structures. Conversely, in agricultural infrastructures having lower risk to human life, there is lack of established safety diagnosis methods. However, considering expansion of high-value smart farm, the importance of plastic greenhouse cannot be overlooked. Therefore, this study aimed to develop on-site diagnosis technique for structural safety of steel structure greenhouse. To build an analysis model, we generated point cloud data of on-site greenhouse using a camera with LiDAR sensor. Subsequently, we extracted points corresponding to pipes using a pre-trained semantic segmentation model, achieving a pipe segmentation accuracy of 78.1%. These points were then converted into 3D frame model, with a location coordinate error of 5.4 cm for nine reference points, as measured by an on-site survey. In FEM structural analysis, nonlinearity of pipe connection was reflected. The loads were determined based on expected wind speed and snow depth in Korea. The structural safety of on-site model was diagnosed more vulnerable with 10.3% higher maximum axial stress, compared with standard model. Through this research, we expect the quantitative safety diagnosis of predicting greenhouse collapse risk. In addition, this technique will enable localized reinforcement strategies within the structure.