• Journal of the Microelectronics and Packaging Society
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• v.29 no.1
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• pp.49-54
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• 2022

The copper plating process used to fabricate the submicron damascene pattern of Cu wiring for Si wafer was applied to the plating of a PCB pattern of several tens of microns in size using the same organic additives and current density conditions. In this case, the non-uniformity of the plating thickness inside the pattern was observed. In order to quantitatively analyze the cause, a numerical calculation considering the solution flow and electric field was carried out. The calculation confirmed that the depletion of Cu²⁺ ions in the solution occurred relatively earlier at the bottom corner than the upper part of the pattern due to the plating of the sidewall and the bottom at the corner of the pattern bottom. The diffusion coefficient of Cu²⁺ ions is 2.65 10^-10 m²/s, which means that Cu²⁺ ions move at 16.3 ㎛ per second on average. In the cases of small damascene patterns, the velocity of Cu²⁺ ions is high enough to supply sufficient ions to the inside of the patterns, while sufficient time is required to replenish the exhausted copper ions in the case of a PCB pattern having a size of several tens of microns. Therefore, it is found that the thickness uniformity can be improved by reducing the current density to supply sufficient copper ions to the target area.

• Composites Research
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• v.35 no.2
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• pp.93-97
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• 2022

The application of infrared heating in the hot press forming of the thermoplastic composites is conducive to productivity with high-speed heating. However, high energy, high forming temperature, and high-speed heating derived from infrared heating can cause material degradation and deteriorate properties such as re-melting performance. Therefore, this study was conducted to optimize the process conditions of the hot press forming suitable for carbon fiber reinforced polyetherketoneketone(CF/PEKK) composites that are actively researched and developed as high-performance aviation materials. Specifically, the degradation mechanisms and properties that may occur in infrared high-speed heating were evaluated through morphological and thermal characteristics analysis and mechanical performance tests. The degradation mechanism was analyzed through morphological investigation of the crystal structure of PEKK. As a result, the size of the spherulite decreased as the degradation progressed, and finally, the spherulite disappeared. In thermal characteristics, the melting temperature, crystallization temperature and heat of crystallization tend to decrease as degradation progresses, and the crystal structure disappeared under long-term exposure at 460℃. In addition, the low bonding strength was observed on the degraded surface, and the bonding surfaces of PEKK did not melt intermittently. In conclusion, it was confirmed that the CF/PEKK composite material degraded at 420℃ in the infrared high-speed heating. Furthermore, the spherulite experienced morphological changes and the re-melting properties of thermoplastic materials were degraded.

• Journal of the Korean earth science society
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• v.43 no.1
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• pp.23-29
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• 2022

Although tropical cyclones with wind speeds weaker than 17 ms^-1 (weak tropical cyclones: WTCs) can cause significant damage, particularly over the Seoul metropolitan area, only a few studies have focused on WTC activity over South Korea. In this study, we found that WTC activity is likely associated with the Pacific Decadal Oscillation (PDO). During the negative phases of the PDO, landfall frequency of WTCs increased significantly compared to the positive phases at 95% confidence level. When related to the negative phases of the PDO, a positive relative vorticity anomaly is found in the northern sector of the western North Pacific while a negative relative vorticity anomaly and enhanced vertical wind shear prevail in the southern sector of the WNP. These factors are favorable for the northward shift of the genesis location of tropical cyclones on average, thereby reducing the total lifetime of WTCs. Moreover, a high-pressure anomaly over the Japanese islands would shift a tropical cyclone track westward in addition to the landfall location. Consequently, the effects of the topographical friction and the Yellow Sea Bottom Cold Water on a tropical cyclone may increase. These conditions could result in a weaker lifetime maximum intensity and landfall intensity, ultimately resulting in WTCs becoming more frequent over South Korea during the negative phases of the PDO.

• Journal of the Korean Applied Science and Technology
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• v.39 no.4
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• pp.552-559
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• 2022

Atopic dermatitis (AD) is a chronic inflammatory skin disease accompanied by severe itching, mainly before five. The aim of this study is to investigate the effects of 405 nm+850 nm LED light therapy on AD-like symptoms in NC/Nga mice. The mice were randomly placed in the normal (Vehicle), atopic dermatitis-induced (CON), and 405 nm + 850 nm LED light therapy (LED) groups. The LED experimental group conducted 405 nm+850 nm wavelength LED ray therapy for 10 minutes a day for seven days. LED light therapy research confirmed the improvement and improvement of Dermatics score and observed the reduction of epidermal tissue thickness caused by dermatitis. Based on the significant decrease of serum IL-1𝛽 and transdermal moisture loss and serum IgE concentration due to LED light therapy, LED light therapy can help restore normal skin conditions in mice that cause atopic dermatitis. This study showed the anti-atopic effect of infrared light and blue light. Light in mice with atopic dermatitis led to the simultaneous use of circular LEDs with two wavelengths.

• Journal of Korea Port Economic Association
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• v.37 no.4
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• pp.41-50
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• 2021

This study investigated what the general public thinks about the shipping industry and how important it is. As a result of the study, more than half of the respondents answered that they knew a little about the shipping industry or that they were normally knew about the shipping industry. Regarding the necessity of budget input to prevent bankruptcy of national shipping companies, it was found that more than half of the respondents answered that it was necessary or moderate. Regarding the necessity of maintaining a national shipping companies, 53% of respondents said it was necessary, and 23% of respondetns said it was normal. However, when asked if they thought that maintaining a national shipping companies would benefit me and my family, 39% of respondetns answered "normal" and 28% of respondetns answered "mostly". As for the cause of Hanjin Shipping's bankruptcy, 49% of respondents said that the owners' family members were immoral and incompetent, and 17.4% of respondetns said that the shipping market conditions deteriorated. Regarding the necessity of fostering the shipping industry, foreign currency acquisition and service balance improvement through export of shipping services accounted for 43.5%, and smooth transportation of import and export cargo accounted for 36.5%. When asked what kind of damage I suffered from Hajin Shipping's bankruptcy, 54.6% answered other (not much), and 14.5% said inflation. Abouve these results, this study gave implication in terms of public promotion and transparent business management.

• Journal of Korean Tunnelling and Underground Space Association
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• v.24 no.1
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• pp.57-78
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• 2022

The disc cutter and cutterbit, which are the most important factors to increase the excavation efficiency of TBM, are key factors in the design and construction of the cutter head. The arrangement, spacing, number, size, and material of disc cutters suitable for the ground conditions determine the success or failure of TBM construction. The disc cutter, which is a representative consumable part in TBM construction, can cause enormous disruption to the construction cost as well as the construction cost unless accurate prediction of wear and replacement cycle is accompanied. Therefore, in this study, the method of calculating the replacement cycle of the disc cutter calculated at the time of design for the slurry shield TBM field, and the depth of wear and replacement location of the disc cutter that occurred during actual construction were compared by analyzing the field data. For a quantitative comparison, weathered soil/weathered rock, soft rock, and hard rock were classified according to the ground in the section showing constant excavation data, and the trajectory of circle was different depending on the location of the disc cutter, so it was compared and analyzed.

• Journal of the Society of Disaster Information
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• v.18 no.3
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• pp.574-580
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• 2022

Purpose: As corn oil is semi-drying oil, it has more double bonds than non-drying oil and is easier to combine with oxygen. In addition, among the causes of spontaneous ignition, accidents caused by oil-soaked cloths due to oxidative heat are gradually increasing. Therefore, the purpose of this study is to understand the characteristics of spontaneous combustion according to the number of towels and the amount of corn oil at 65℃. Method: After setting the test temperature to 65℃, 25ml, 50ml, 75ml of corn oil per towel was sprayed. The central temperature of the sample rises above the set temperature. It was determined, and when the central temperature of the sample became similar to the set temperature, it was determined as non-igniting. Result: After evenly distributing 25ml of corn oil per towel, as a result of the experiment, 5 towels did not ignite, and 10 and 15 towels ignited. Also, as a result of an experiment using 50ml and 75ml of corn oil per towel, spontaneous ignition occurred when the number of towels was 5, 10, or 15 sheets. Conclusion: Even a small amount can cause a fire if the conditions for spontaneous ignition are met.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.48 no.3
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• pp.287-293
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• 2022

Gray hair is a representative sign of aging. Intrinsic aging, stress, and the external environment cause hair graying. Stress is known to be a major factor in the early onset of hair graying. We previously found that Pueraia lobata root extract (PLRE) can prevent hair graying by promoting melanin formation. However, it remains unknown whether PLRE can prevent hair graying induced by conditions of stress. In this study, we confirmed the effect of PLRE on stress-induced hair graying. A reporter cell line was newly constructed to confirm the expression of microphthalamia-associated transcription factor (MITF), the main transcription factor for melanin production. MITF expression and melanin pigmentation were reduced in human hair follicle tissue treated with the stress hormone cortisol or H₂O₂ to induce oxidative stress. PLRE treatment restored MITF expression and increased the amount of melanin pigment in the hair follicle. The expression of Tyrosinase related proteins-2 (TRP-2), a melanin synthesis enzyme in the hair follicle, also increased. In conclusion, PLRE can effectively prevent the inhibition of melanin synthesis by stress hormones and oxidative stress.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.5
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• pp.118-127
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• 2021

Recently, the public's interest in the air environment has increased, and public health is threatened by fine particulate matter. Furthermore, the government continues efforts to improve air quality by expanding the monitoring of air pollutants and reinforcing environmental standards. Since air quality differs depending on the region in the Korean Peninsula, it is currently necessary to identify the cause and search for influencing factors. In this study, the atmospheric environment and regional differences in cities located in the Chungnam Province were observed. As a research method, regression analysis was performed for weather conditions, such as temperature, wind speed, precipitation, and season and targeted at air pollutants, such as SO₂, NO₂, CO, O₃, PM₁₀, and PM_2.5, as well as heavy metals contained in particulate matter, such as Pb, Cd, Cr, Cu, Ni, As, Mn, Fe, Al, Ca, and Mg. In the case of PM₁₀, the concentrations of Mn(0.4884) in Cheonan, CO(0.3329) in Dangjin, and Mg(0.5691) in Seosan were highest. In the case of PM_2.5, Cheonan NO₂(0.4759), Dangjin CO(0.4128), and Seosan NO₂(0.3715) were significantly affected. In summary, the influencing factors vary according to the region in Chungnam province in terms of air quality, and there is a difference in the degree of contribution. Therefore, it is considered that the Korean government's management of air quality is required for each region.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.4
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• pp.506-513
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• 2021

The durability and safety of reinforced concrete structures significantly depend on the reinforcement conditions, concrete cover thickness, cracks, and concrete strength. There are two ways to accurately determine the information on reinforcing bars embedded in concrete - the local destructive method and the non-destructive rebar detection test. In general, the non-destructive rebar detection tests, such as the electromagnetic wave radar method, electromagnetic induction method, and radiation method, are adopted to avoid damage to the structural elements. The moisture content and temperature of concrete affect the dielectric constant, which is the electrical property of concrete, and cause interference in the non-destructive rebar detection test results. Therefore, in this study, the effects of the electromagnetic wave radar method and electromagnetic induction method have been analyzed according to the temperature and surface moisture content of concrete. Due to the technological advancement and development of equipment, the average error rate was less than 5% in the specimens at 24℃, irrespective of their operating principles. Among the tested methods, the electromagnetic induction method showed very high accuracy. The electromagnetic wave radar method indicated a relatively small error rate in the dry state than in the wet state, and exhibited a relatively high error rate at high temperatures. It was confirmed that the error could be reduced by applying the electromagnetic wave radar method when the temperature of the probe was low and in a dry state, and by using the electromagnetic induction method when the probe was in a wet state or at a high temperature.