• Journal of Powder Materials
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• v.29 no.1
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• pp.14-21
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• 2022

In the powder bed fusion (PBF) process, a 3D shape is formed by the continuous stacking of very fine powder layers using computer-aided design (CAD) modeling data, following which laser irradiation can be used to fuse the layers forming the desired product. In this method, the main process parameters for manufacturing the desired 3D products are laser power, laser speed, powder form, powder size, laminated thickness, and laser diameter. Stainless steel (STS) 316L exhibits excellent strength at high temperatures, and is also corrosion resistant. Due to this, it is widely used in various additive manufacturing processes, and in the production of corrosion-resistant components with complicated shapes. In this study, rectangular specimens have been manufactured using STS 316L powder via the PBF process. Further, the effect of heat treatment at 800 ℃ on the microstructure and hardness has been investigated.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.163-163
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• 2000

In this research, we used the ion irradiation technique which has an advantae in improving intentionally the properties of surface and interface in a non-equilibrium, instead of the conventional annealing method which has been known to improve the material properties in the equilibrium stat. Cu/Co multilayered films were prepared on SiN4/SiO2/Si substrates by the electron-beam evaporation for the Co layers and the thermal evaporation for the Cu layers in a high vacuum. The ion irradiation with a 80keV Ar+ was carried out at various ion doses in a high vacuum. Hysteresis loops of the films were investigated by magneto-optical polar Kerr spectroscopy at various experimental conditions. The change of atomic structure of the films before and after the ion irradiation was studied by glancing angle x-ray diffraction, and the intermixing between Co and Cu sublayers was confirmed by Rutherford backscattering spectroscopy. The surface roughness and magneto-resistance were measured by atomic force microscopy and with a four-point probe system, respectively. During the magneto-resistance measurement, we changed temperature and the direction of magnetization. From the results of experiments, we found that the change at the interfaces of the Cu/Co multilayered film induced by ion irradiation cause the change of magnetic properties. According to the change in hysteresis loop, the surface inplane component of magnetic easy axis was isotropic before the ion irradiation, but became anisotropic upon irradiation. It was confirmed that this change influences the axial behavior of magneto-resistance. Especially, the magneto-resistance varied in accordance with an external magnetic field and the direction of current, which means that magneto-resistance also shows the uniaxial behavior.

• Journal of Powder Materials
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• v.30 no.3
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• pp.268-275
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• 2023

The demand for energy is steadily rising because of rapid population growth and improvements in living standards. Consequently, extensive research is being conducted worldwide to enhance the energy supply. Transpiration power generation technology utilizes the vast availability of water, which encompasses more than 70% of the Earth's surface, offering the unique advantage of minimal temporal and spatial constraints over other forms of power generation. Various principles are involved in water-based energy harvesting. In this study, we focused on explaining the generation of energy through the streaming potential within the generator component. The generator was fabricated using sugar cubes, PDMS, carbon black, CTAB, and DI water. In addition, a straightforward and rapid manufacturing method for the generator was proposed. The PDMS generator developed in this study exhibits high performance with a voltage of 29.6 mV and a current of 8.29 µA and can generate power for over 40h. This study contributes to the future development of generators that can achieve high performance and long-term power generation.

• The Plant Pathology Journal
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• v.40 no.3
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• pp.261-271
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• 2024

Sulfur is one of the inorganic elements used by plants to develop and produce phytoalexin to resist certain diseases. This study reported a method for preparing a material for plant disease resistance. Sulfur nanoparticles (SNPs) stabilized in the chitosan-Cu²⁺ (CS-Cu²⁺) complex were synthesized by hydrolysis of Na₂S₂O₃ in an acidic medium. The obtained SNPs/CS-Cu²⁺ complex consisting of 0.32% S, 4% CS, and 0.7% Cu (w/v), contained SNPs with an average size of ~28 nm as measured by transmission electron microscopy images. The X-ray diffraction pattern of the SNPs/CS-Cu²⁺ complex showed that SNPs had orthorhombic crystal structures. Interaction between SNPs and the CS-Cu²⁺ complex was also investigated by ultraviolet-visible. Results in vitro nematicidal effect of materials against Meloidogyne incognita showed that SNPs/CS-Cu²⁺ complex was more effective in killing second-stage juveniles (J2) nematodes and inhibiting egg hatching than that of CS and CS-Cu²⁺ complex. The values of LC₅₀ in killing J2 nematodes and EC₅₀ in inhibiting egg hatching of SNPs/CS-Cu²⁺ complex were 75 and 51 mg/l, respectively. These values were lower than those of CS and the CS-Cu²⁺ complex. The test results on the nematicidal effect against M. incognita on coffee pots showed that the SNPs/CS-Cu²⁺ complex was 100% effective at a concentration of 150 mg/l. Therefore, the SNPs/CS-Cu²⁺ complex could be considered as a biochemical material with potential for agricultural applications to control root-knot nematodes.

• Journal of Ginseng Research
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• v.48 no.4
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• pp.417-424
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• 2024

Background: This research main objective was to evaluate a proliposomes (PLs) formulation for the enhancement of oral bioavailability of ginsenosides, using ginsenoside Rg3 (Rg3) as a marker. Methods: A novel PLs formulation was prepared using a modified evaporation-on-matrix method. Soy phosphatidylcholine, Rg3-enriched extract, poloxamer 188 (Lutrol® F 68) and sorbitol were mixed and dissolved using a aqueous ethanolic solution, followed by the removal of ethanol and lyophilization. The characterization of Rg3-PLs formulations was performed by powder X-ray diffractometry (PXRD), transmission electron microscopy (TEM) and in vitro release. The enhancement of oral bioavailability was investigated and analyzed by noncompartmental parameters after oral administration of the formulations. Results: PXRD of Rg3-PLs indicated that Rg3 was transformed from crystalline into its amorphous form during the preparation process. The Rg3-encapsulated liposomes with vesicular-shaped morphology were generated after the reconstitution by gentle hand-shaking in water; they had a mean diameter of approximately 350 nm, a negative zeta potential (- 28.6 mV) and a high entrapment efficiency (97.3%). The results of the in vitro release study exhibited that significantly more amount of Rg3 was released from the PLs formulation in comparison with that from the suspension of Rg3-enriched extract (control group). The pharmacokinetic parameters after oral administration of PLs formulation in rats showed an approximately 11.8-fold increase in the bioavailability of Rg3, compared to that of the control group. Conclusion: The developed PLs formulation could be a favorable delivery system to improve the oral bioavailability of ginsenosides, including Rg3.

• International Journal of Computer Science & Network Security
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• v.23 no.12
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• pp.101-106
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• 2023

Chronic illnesses are among the most common serious problems affecting human health. Early diagnosis of chronic diseases can assist to avoid or mitigate their consequences, potentially decreasing mortality rates. Using machine learning algorithms to identify risk factors is an exciting strategy. The issue with existing feature selection approaches is that each method provides a distinct set of properties that affect model correctness, and present methods cannot perform well on huge multidimensional datasets. We would like to introduce a novel model that contains a feature selection approach that selects optimal characteristics from big multidimensional data sets to provide reliable predictions of chronic illnesses without sacrificing data uniqueness.[1] To ensure the success of our proposed model, we employed balanced classes by employing hybrid balanced class sampling methods on the original dataset, as well as methods for data pre-processing and data transformation, to provide credible data for the training model. We ran and assessed our model on datasets with binary and multivalued classifications. We have used multiple datasets (Parkinson, arrythmia, breast cancer, kidney, diabetes). Suitable features are selected by using the Hybrid feature model consists of Lassocv, decision tree, random forest, gradient boosting,Adaboost, stochastic gradient descent and done voting of attributes which are common output from these methods.Accuracy of original dataset before applying framework is recorded and evaluated against reduced data set of attributes accuracy. The results are shown separately to provide comparisons. Based on the result analysis, we can conclude that our proposed model produced the highest accuracy on multi valued class datasets than on binary class attributes.[1]

• Nuclear Engineering and Technology
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• v.56 no.10
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• pp.4050-4055
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• 2024

This research intends to utilize melt-quenching technique in order to examine the radiation shielding capability of 10 % Mo, 10 % Na2O, 20 % PbO, and 60 % B₂O₃ glass system, with varying CaO, TiO₂, CuO, Fe₂O₃ or Mo. XCOM and MCNP simulations were utilized to analyze the radiation shielding properties of the fabricated glasses. The results revealed CuO having the superior MAC of 49.91 cm²/g, then Fe₂O₃ with 49.24 cm²/g, followed by CaO with 49.10 cm²/g, and TiO₂ with 48.49 cm²/g as the least. CuO and Fe₂O₃ were confirmed to have least HVL compared to CaO and TiO₂. The value of the lead equivalent thickness showed fluctuation against the gamma energy, where it raisess within the photoelectric region and falls after the photoelectric region. The data reveal that, the lead equivalent thickness at 0.1 MeV were 7.88 cm, 7.86 cm, 7.81 cm and 7.80 cm for TiO₂, Fe₂O₃, CaO, and CuO in the same order, respectively. The transmission factor (TF) raises as the gamma energy raises, having TiO₂ as the highest with 76.068 %, while the radiation protection efficiency dropped as the energy raises.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.35 no.2
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• pp.93-101
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• 1999

A simple experimental method was used in an attempt to realize the elevation of the fishing ability of purse seine in the sea area of Cheju Island, the changes of seine volume and tension in the purseline during pursing. Experiments carried out on the six types simplified reduced model seines which were made of knotless nettings. The nettings were woven in different leg length 4.3, 5.0, 5.5, 6.0, 6.6 and 7.7mm of polyester 28 tex two threads two-ply twine, and each of the seines were named I, II, III, IV, V and Ⅵ seine. Dimension of seine models were 450cm for corkline and 85cmfor seine depth, each seines rigged up 160g of float for a floatline and 50g (underwater weight) of lead for a leadline. These model purse seines were made of the scale of 1/200 of its full scale, a 120 ton in the near sea of Cheju Island. Designing and testing for the model purse seines were based on the Tauti's law. Experiments were measured in the observation channel of a flume tank at the static conditions set up shooting and pursing equipments. Motion of purse seine during purse line was recorded by the two sets video camera for VTR which were placed in top and front of the model seine. The reading coordinate of seine volume carried out by the video digitization system, disk data for the purseline tension. An analysis were performed on the changes seine volume and tension in the purseline during pursing. The results obtained were as follows: 1. The seine volume during pursing was largest for Ⅵ seine with smallest d/l followed by V, IV, III, II and I seines, and tension in the purseline was small. 2. Seine volume during pursing can be expressed by the following equation; CVt=l-EXP[｛2.79 (d/l）＋0.35｝t-33.37 (d/l) ＋ 0.57] Where CVt is volume ratio, d is twine diameter, l is leg length and t is pursing time (sec). 3. Tension in the purse line during pursing can be expressed by the following equation; T= 1- EXP ｛0.57t ＋ 13.36 (d/l)+2.97｝ Where T is tension (kg) in the purseline during pursing.

• Restorative Dentistry and Endodontics
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• v.24 no.1
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• pp.40-48
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• 1999

This study was designed to examine the specificities of the designed primers for F. nucleatum and F. necrophorum and to compare the PCR results using clinical samples with those of the anaerobic culture method. F. nucleatum and F. necrophorum spp. are frequently isolated in infected root canals, and they are related to periapical diseases. F. nucleatum(VPI 10197) and F. necrophorum(ATCC 25286) were used as references for PCR reaction, and thirty five teeth with one canal and periapical lesion were used. The samples were cultured anaerobically and identified using Rapid ID 32A(BioMerieux Vitek, Inc., France) as biochemical battery. In the GenBank database, species-specific PCR primers(nuc1/nuc2 primers for F. nucleatum and nec1/nec2 primers for F. necrophorum) were designed from the 16S ribosomal DNA(rDNA) sequences of F. nucleatum(accession number M58683) and F. necrophorum(accession number AF044948). PCR procedures of F. nucleatum(VPI 10197) and F. necrophorum (ATCC 25286) were simulated on a computer software. Amplify(v.1.2${\beta}$ for Macintosh). 820 bps and 817 bps of nucleotides were expected, respectively. Using extracted DNAs with QiaAmp tissue kit(Qiagen co., Germany), PCR was done. The results were as follows : 1. The nuc1/nuc2 primers produced an amplicon of 820 bps and the nec1/nec2 primers produced an amplicon of 817 bps. 2. The nuc1/nuc2 primers and the nec1/nec2 primers were specific and did not react with species other than the designated ones(i.e. nuc1/nuc2 primers did not produce amplicons for F. necrophorum, and vice versa.). And the PCR products of Porphyromonas endodontalis(ATCC 35406), Porphyromonas gingivalis(ATCC 33277), Prevotella intermedia(ATCC 25611), and Prevotella nigrescens(ATCC 33563), frequently isolated in infected root canals and periapical lesions, were not amplified by the primers specific for Fusobacterium nucleatum and Fusobacterium necrophorum. 3. This method utilizing PCR could detect F. nucleatum and F. necrophorum in clinical samples, while anaerobic culture method could detect neither.

• Journal of Biosystems Engineering
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• v.35 no.5
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• pp.343-349
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• 2010

Rapid on-site sensing of nitrate-nitrogen and potassium ions in hydroponic solution would increase the efficiency of nutrient use for greenhouse crops cultivated in closed hydroponic systems while reducing the potential for environmental pollution in water and soil. Ion-selective electrodes (ISEs) are a promising approach because of their small size, rapid response, and the ability to directly measure the analyte. The capabilities of the ISEs for sensing nitrate and potassium in hydroponic solution can be affected by the presence of other ions such as calcium, magnesium, sulfate, sodium, and chloride in the solution itself. This study was conducted to investigate the applicability of two ISEs consisting of TDDA-NPOE and valinomycin-DOS PVC membranes for quantitative determinations of $NO_3$-N and K in hydroponic solution. Nine hydroponic solutions were prepared by diluting highly concentrated paprika hydroponic solution to provide a concentration range of 3 to 400 mg/L for $NO_3$-N and K. Two of the calibration curves relating membrane response and nutrient concentration provided coefficients of determination ($R^2$) > 0.98 and standard errors of calibration (SEC) of < 3.79 mV. The use of the direct potentiometry method, in conjunction with an one-point EMF compensation technique, was feasible for measuring $NO_3$-N and K in paprika hydroponic solution due to almost 1:1 relationships and high coefficients of determination ($R^2$ > 0.97) between the levels of $NO_3$-N and K obtained with the ion-selective electrodes and standard instruments. However, even though there were strong linear relationships ($R^2$ > 0.94) between the $NO_3$-N and K concentrations determined by the Gran's plot-based multiple standard addition method and by standard instruments, hydroponic $NO_3$-N concentrations measured with the ISEs, on average, were about 10% higher than those obtained with the automated analyzer whereas the K ISE predicted about 59% lower K than did the ICP spectrometer, probably due to no compensation for a difference between actual and expected concentrations of standard solutions directly prepared.