• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.16 no.4
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• pp.203-209
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• 2023

Harmony search(HS) does not use the evaluation of individual harmony when referring to HM when constructing a new harmony, but particle swarm optimization(PSO), on the contrary, uses the evaluation value of individual particles and the evaluation value of the population to find a solution. However, in this study, we tried to improve the performance of the algorithm by finding and identifying similarities between HS and PSO and applying the particle improvement process of PSO to HS. To apply the PSO algorithm, the local best of individual particles and the global best of the swam are required. In this study, the process of HS improving the worst harmony in harmony memory(HM) was viewed as a process very similar to that of PSO. Therefore, the worst harmony of HM was regarded as the local best of a particle, and the best harmony was regarded as the global best of swam. In this way, the performance of the HS was improved by introducing the particle improvement process of the PSO into the HS harmony improvement process. The results of this study were confirmed by comparing examples of optimization values for various functions. As a result, it was found that the suggested HS-PSO was much better than the existing HS in terms of accuracy and consistency.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.16 no.2
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• pp.97-103
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• 2023

Since most of the information is transmitted through the network, eavesdropping and interception by a third party may occur. Appropriate measures are required for effective, secure and confidential communication in the network. Steganography is a technology that prevents third parties from detecting that confidential information is hidden in other media. Due to structural vulnerabilities, information protected by encryption and steganography techniques can be easily exposed to illegitimate groups. In order to improve the limitations of LSB where the simplicity and predictability of the hiding method exist, I propose a technique to improve the security of the message to be hidden based on PRNG and recursive function. To enhance security and confusion, XOR operation was performed on the result of selecting a random bit from the upper bits of the selected channel and the information transformed by the RS-box. PSNR and SSIM were used to confirm the performance of the proposed method. Compared to the reference values, the SSIM and PSNR of the proposed method were 0.9999 and 51.366, respectively, confirming that they were appropriate for hiding information.

• Membrane and Water Treatment
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• v.14 no.2
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• pp.85-93
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• 2023

Membrane separation is widely used for several applications such as water treatment, membrane reactors and climate change. Cross-linked organic-inorganic hybrid polyvinylidene fluoride (PVDF) / Tetraethyl orthosilicate (TEOS) was adopted for the preparation of optimized hollow membrane (HFM) for membrane distillation or other low pressure separators for mechanical properties and permeability under varying pretreatment schemes. HFMs were prepared on semi-pilot membrane fabrication system. Novel adopted post-treatment schemes involved soaking in glycerol, magnesium sulphate (MgSO₄), sodium hypochlorite (NaOCl), and isopropanol for different durations. All fibers were characterized for morphology using a scanning electron microscope (SEM), surface roughness using atomic force microscope (AFM), elemental composition by examining Energy Dispersive Spectroscopy (EDS), water contact angle (CA°) and porosity. The performance of the fibers was evaluated for pure water permeation flux (PWF). Post-treatment with MgSO₄ gave the highest both tensile modulus and flux. Assessment of properties and performance revealed comparable results with other organic-inorganic separators, HF or flat. In spite of few reported data on post treatment using MgSO₄ in presence of TEOS, this proves the potential of low cost treatment without negative impact on other membrane properties. The flux is also comparable with hypochlorite which manifests substantial precaution requirements in actual industrial use.The relatively high values of flux/bar for sample treated with TEOS, post treated with MgSO₄ and hypochlorite are 88 and 82 LMH/bar respectively.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.10a
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• pp.243-245
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• 2021

Existing beacons are suitable for providing untact services, but they have the disadvantage of difficulty in accurate indoor positioning because the deviation in signal strength increases depending on the environment. In general, trilateration technique can reduce deviation, but if the distance between beacons is quite irregular, it becomes difficult to apply the algorithm. Therefore, in this paper, we studied how to reduce the signal power measurement error between beacons. First, we transformed the distance measurement formula using RSSI, assuming that the TX values were the same. In addition, we compared measurement errors with existing beacons by searching beacons with beacons scanner applications implemented with Android. As a result, it was confirmed that if a certain distance was further away, the measurement was measured more accurately than the non-changing beacon. Through this, accurate indoor positioning will be possible even in various disability situations. It is also expected that there will be more cases of establishing services that combine beacon with non-face-to-face services.

• Journal of the Earthquake Engineering Society of Korea
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• v.26 no.2
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• pp.71-82
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• 2022

This paper presents the effect on the inelastic behavior and structural performance of concrete and filled steel pipe through a numerical method for reliable judgment under various load conditions of the CJS composite structural system. Variable values optimized for the CJS synthetic structural system and the effects of multiple variables used for finite element analysis to present analytical modeling were compared and analyzed with experimental results. The Winfrith concrete model was used as a concrete material model that describes the confinement effect well, and the concrete structure was modeled with solid elements. Through geometric analysis of shell and solid elements, rectangular steel pipe columns and steel elements were modeled as shell elements. In addition, the slip behavior of the joint between the concrete column and the rectangular steel pipe was described using the Surface-to-Surface function. After finite element analysis modeling, simulation was performed for cyclic loading after assuming that the lower part of the foundation was a pin in the same way as in the experiment. The analysis model was verified by comparing the calculated analysis results with the experimental results, focusing on initial stiffness, maximum strength, and energy dissipation capability.

• Restorative Dentistry and Endodontics
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• v.49 no.1
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• pp.9.1-9.14
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• 2024

Objectives: This study aimed to evaluate the effect of pomegranate solution (Punica granatum) on eroded dentin through antioxidant action, shear bond strength (SBS) and interface morphology. Materials and Methods: The 10% pomegranate peel extract was prepared by the lyophilization method. Punicalagin polyphenol was confirmed by high-performance liquid chromatography. Antioxidant activity was evaluated by capturing the 2,2-diphenyl1-picrylhydrazyl (DPPH) radical. For the SBS, 48 dentin fragments were divided into sound or eroded, and subdivided according to the pretreatment (n = 12): water or P. granatum. The surfaces were restored with self-etch adhesive and a bulk-fill resin (Ecosite; DMG). The SBS was done immediately (24 hours) and after thermal cycling + water storage (12 months). For scanning electron microscopy, 48 dentin fragments (24 sound and 24 eroded) received the same treatments as for SBS (n = 6), and they were analyzed after 24 hours and 12 months. Results: The P. granatum had antioxidant action similar (p = 0.246) to the phenolic standard antioxidants. After 24 hours, eroded dentin had lower SBS than sound dentin (p < 0.001), regardless of the pretreatment. After 12 months, P. granatum maintained the SBS of sound dentin (13.46 ± 3.42 MPa) and eroded dentin (10.96 ± 1.90 MPa) statistically similar. The lowest values were found on eroded dentin treated with water (5.75 ± 1.65 MPa) (p < 0.001). P. granatum on eroded dentin caused peritubular demineralization and hybrid layer with resin tags. Conclusions: The pomegranate extract had antioxidant action and preserved the adhesive interface of the eroded dentin.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.18 no.1
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• pp.46-63
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• 2024

One of the biggest dangers in the globe is water contamination. Water is a necessity for human survival. In most cities, the digging of borewells is restricted. In some cities, the borewell is allowed for only drinking water. Hence, the scarcity of drinking water is a vital issue for industries and villas. Most of the water sources in and around the cities are also polluted, and it will cause significant health issues. Real-time quality observation is necessary to guarantee a secure supply of drinking water. We offer a model of a low-cost system of monitoring real-time water quality using IoT to address this issue. The potential for supporting the real world has expanded with the introduction of IoT and other sensors. Multiple sensors make up the suggested system, which is utilized to identify the physical and chemical features of the water. Various sensors can measure the parameters such as temperature, pH, and turbidity. The core controller can process the values measured by sensors. An Arduino model is implemented in the core controller. The sensor data is forwarded to the cloud database using a WI-FI setup. The observed data will be transferred and stored in a cloud-based database for further processing. It wasn't easy to analyze the water quality every time. Hence, an Optimized Neural Network-based automation system identifies water quality from remote locations. The performance of the feed-forward neural network classifier is further enhanced with a hybrid GA- PSO algorithm. The optimized neural network outperforms water quality prediction applications and yields 91% accuracy. The accuracy of the developed model is increased by 20% because of optimizing network parameters compared to the traditional feed-forward neural network. Significant improvement in precision and recall is also evidenced in the proposed work.

• Journal of The Korean Society of Grassland and Forage Science
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• v.28 no.3
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• pp.185-192
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• 2008

We have studied effect of water treatment sludge (WTS) on trace metals of sorghum hybrid (Sorghum bicolor (L.) Moench). In the present report it was for cadmium (Cd) content on background correction (BGC) mode with an atomic absorption spectrophotometer. The four treatments were Control, Compost, Alum + nitrogen, phosphorus, potassium (NPK), Compost + NPK. In the analysis, burner height of the atomic absorption spectrophotometer was adjusted to three levels; 3 mm, 6 mm, 9 mm. As a conclusion, 3 mm and 6 mm burner height conditions were better than 9 mm height for Cd analysis. And the conditions for widening the range, the mean, and the standard deviation (SD) values of observed absorbances as well as the condition for lessening the mean of observed background values are necessary for getting the better measuring of Cd. At the present experiment, 6 mm burner height condition is the best among the three burner heights.

• Korean Journal of Radiology
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• v.25 no.4
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• pp.384-394
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• 2024

Objective: To evaluate the image quality of novel dark-blood computed tomography angiography (CTA) imaging combined with deep learning reconstruction (DLR) compared to delayed-phase CTA images with hybrid iterative reconstruction (HIR), to visualize the cervical artery wall in patients with Takayasu arteritis (TAK). Materials and Methods: This prospective study continuously recruited 53 patients with TAK (mean age: 33.8 ± 10.2 years; 49 females) between January and July 2022 who underwent head-neck CTA scans. The arterial- and delayed-phase images were reconstructed using HIR and DLR. Subtracted images of the arterial-phase from the delayed-phase were then added to the original delayed-phase using a denoising filter to generate the final-dark-blood images. Qualitative image quality scores and quantitative parameters were obtained and compared among the three groups of images: Delayed-HIR, Dark-blood-HIR, and Dark-blood-DLR. Results: Compared to Delayed-HIR, Dark-blood-HIR images demonstrated higher qualitative scores in terms of vascular wall visualization and diagnostic confidence index (all P < 0.001). These qualitative scores further improved after applying DLR (Dark-blood-DLR compared to Dark-blood-HIR, all P < 0.001). Dark-blood DLR also showed higher scores for overall image noise than Dark-blood-HIR (P < 0.001). In the quantitative analysis, the contrast-to-noise ratio (CNR) values between the vessel wall and lumen for the bilateral common carotid arteries and brachiocephalic trunk were significantly higher on Dark-blood-HIR images than on Delayed-HIR images (all P < 0.05). The CNR values were significantly higher for Dark-blood-DLR than for Dark-blood-HIR in all cervical arteries (all P < 0.001). Conclusion: Compared with Delayed-HIR CTA, the dark-blood method combined with DLR improved CTA image quality and enhanced visualization of the cervical artery wall in patients with TAK.

• Journal of the korean academy of Pediatric Dentistry
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• v.29 no.4
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• pp.509-518
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• 2002

The purpose of this study was to evaluate the bonding of compomer to deciduous dentin which is known to have been developed to improve the weak properties of glass ionomer cement and composite resin. 120 sound primary molars were used for the shear bond strength test and another 24 for the scanning electron microscopic evaluation. Each material was ailed into polyethylene mold attached to exposed dentinal surface($3{\times}4mm$ in diameter) of sample blocks. Shearbond strength was measured using Universal testing machine and data were analyzed statistically with Oneway-ANOVA and Scheffe test. Scanning electron microscopic observation was performed in order to evaluate the pattern of distribution and penetration of resin tags and hybrid layer. Compomer groups(II-V) showed significantly higher bond strength values than glass ionomer group(I)(p<.05). Etching-compomer groups(III, V) showed the significantly higher bond strength than non-etching compomer groups(II, IV)(p<.05), but slightly lower values than composite resin group(VI) with no statistically significant difference(p>.05). No significantly different bond strength was found between compomer groups of different bonding system(p>.05). Scanning electron micrographs showed more irregular distribution of short and thin resin tags in non-etching compomer groups(II, IV) whereas the more regular and intimate distribution of long and thick tags in etching compomer groups(III, V) and composite resin group(VI). The evaluation of hybrid layer also showed more regular formation of thicker layer in etching compomer groups(III, V). Based on the results of present study, the use of compomer as an esthetic restorative material for primary molars might be justified.