• Journal of the Korean Wood Science and Technology
• /
• v.35 no.3
• /
• pp.36-44
• /
• 2007

The purpose of this study was to investigate thermal stability, reactivity, and bonding strength of existing epoxy resin mixed with the epoxidized soybean oil (ESBO) in order to use soybean oil economically. In the dry shear test, the marked strengths showed $30.5kgf/cm^2$ at the ratio of ESBO to epoxy resin 9 : 1 and $6.2kgf/cm^2$ at the ratio 8 : 2. The bonding strengths of the others, except mixing ratios 2 : 8 and 1 : 9, exceeded the requirement of Korean plywood standard of $7.0kgf/cm^2$. In the wet shear test, the result was $5.8kgf/cm^2$ at the ratio 9 : 1. There were no thickness swelling and moisture absorption in the water resistance of the film. The value of activation energy, Tg (${\Delta}E$), by DSC analysis showed between $110^{\circ}C$ and $120^{\circ}C$ through all ratios. Epoxy in the epoxy resin fully reacted with the hardener (TETA), but it is difficult to decide that epoxys in the ESBO were reacted directly with the hardener from FT-IR analysis. As the mixing ratio of ESBO increased, the thermal stabilities dropped from TGA analysis. From the comprehensive view on the results of above experiments, it could be confirmed through experiments that the ESBO in the mixed adhesive of epoxy resin/ESBO played a role as an extending agent level of epoxy adhesive, and we were able to know that in order to utilize ESBO as an adhesive, a study should be performed on the condition of hardening, inducible of the hardening reaction.

• Health Policy and Management
• /
• v.12 no.3
• /
• pp.1-22
• /
• 2002

Health is a fundamental human right and a sine qua non for happiness of people and for national development. Government has a responsibility for the provision of health services for their people. Recent changes of disease pattern, i.e. decrease of Infectious diseases and increase of chronic and degenerative diseases Including cancer and cardiovascular diseases, together with universal coverage of health insurance and improved living standard have prompted medical care utilization and skyrocketed the national health expenses. The goal of national health policy is improving the quality of life through the betterment of health level. To achieve this goal it is necessary to establish a healthcare system for lifetime, to improve the efficiency of healthcare delivery system, and to strengthen the public health services for disease prevention and health promotion. The current public health service programs are Inefficient due to an inconsistent policy for health service program, lack of health information system, irrational health program planning and evaluation, and Inadequate training of health workers. Local government has a legal responsibility for health service program planning and promoting the competence of health workers. Thus, municipal and provincial health departments should expand their roles and strengthen their function. The strategies for developing public health service programs at local level are ${\circled}1$ stipulating the goals of health policy, ${\circled}2$ promoting the ability for health program planning and evaluation, ${\circled}3$ establishing health information and surveillance system, ${\circled}4$ training of health workers, ${\circled}5$ establishing an institution for health information management and training of health workers, and ${\circled}61$ collaboration with local universities.

• Journal of Life Science
• /
• v.26 no.1
• /
• pp.50-58
• /
• 2016

The root bark of Ulmus macrocarpa has been used in traditional medicine for the treatment of various diseases such as edema, infection and inflammation. Nevertheless, the biological activities and underlying mechanisms of the immunomodulatory effects remain unclear. In this study, as part of our ongoing screening program to evaluate the immunomodulatory potential of new compounds from traditional medicinal resources, we investigated the effects of U. macrocarpa water extract (UME) on immune modulation in a murine RAW 264.7 macrophage model. As immune response parameters, the productions of as nitric oxide (NO) and cytokines such tumor necrotic factor (TNF)-α, interleukin (IL)-1β and IL-10 were evaluated. Although the release of IL-1β remained unchanged in UME-treated RAW 264.7 macrophages, the productions of NO, TNF-α and IL-10 were significantly increased, along with the increased expression of inducible NO synthase, TNF-α and IL-10 expression at concentrations with no cytotoxicity. UME treatment also induced the nuclear translocation of nuclear factor κB (NF-κB), and phosphorylation of Akt and mitogen-activated protein kinases (MAPKs) indicating that UME activated macrophages through the activation of NF-κB, phosphoinositide-3-kinase (PI3K)/Akt and MAPKs signaling pathways in RAW 264.7 macrophages. Furthermore, pre-treatment with UME significantly attenuated the production of NO, but not TNF-α, IL-1β and IL-10, in lipopolysaccharide-stimulated RAW 264.7 cells suggesting that UME may be useful in preventing inflammatory diseases mediated by excessive production of NO. These findings suggest that the beneficial therapeutic effects of UME may be attributed partly to its ability to modulate immune functions in macrophages.

• Journal of Korean Society of Forest Science
• /
• v.109 no.3
• /
• pp.259-270
• /
• 2020

Extreme weather events, such as heat and drought, have occurred frequently over the past two decades. This has led to continuous reports of cases of forest damage due to physiological stress, not pest damage. In 2014, pine trees were collectively damaged in the forest genetic resources reserve of Sogwang-ri, Uljin, South Korea. An investigation was launched to determine the causes of the dieback, so that a forest management plan could be prepared to deal with the current dieback, and to prevent future damage. This study aimedto 1) understand the topographic and structural characteristics of the area which experienced pine tree dieback, 2) identify the main causes of the dieback, and 3) predict future risk areas through the use of machine-learning techniques. A model for identifying risk areas was developed using 14 explanatory variables, including location, elevation, slope, and age class. When three machine-learning techniques-Decision Tree, Random Forest (RF), and Support Vector Machine (SVM) were applied to the model, RF and SVM showed higher predictability scores, with accuracies over 93%. Our analysis of the variable set showed that the topographical areas most vulnerable to pine dieback were those with high altitudes, high daily solar radiation, and limited water availability. We also found that, when it came to forest stand characteristics, pine trees with high vertical stand densities (5-15 m high) and higher age classes experienced a higher risk of dieback. The RF and SVM models predicted that 9.5% or 115 ha of the Geumgang Pine Forest are at high risk for pine dieback. Our study suggests the need for further investigation into the vulnerable areas of the Geumgang Pine Forest, and also for climate change adaptive forest management steps to protect those areas which remain undamaged.

• Journal of Mushroom
• /
• v.19 no.3
• /
• pp.191-199
• /
• 2021

This study was conducted to improve the useful components and biological activity of Lentinula edodes fermented by lactic acid bacteria (LAB). Three LAB strains (Lactobacillus brevis KCCM 11904, L. plantarum KCCM 354469, and L. fermentum KCCM 12116) were inoculated and used for L. edodes hot water extract (10%, 20%, 30%) fermentation. LAB fermentation of L. edodes hot water extracts decreased pH and thus were more acidic than non-fermented L. edodes hot water extract. β-glucan and ergothioneine contents were increased by L. edodes in a concentration-dependent manner. The ergothioneine and β-glucan contents were highest in fermented with 30% L. edodes hot water extract fermented by L. plantarum and L. brevis (40.48 mg/100 g and 13.94%, respectively). The hepato-protective effect of fermented L. edodes hot water extracts by the three LAB were tested using Sprague-Dawley rat primary hepatocytes. In primary hepatocytes obtained following liver injury induced by acetaminophen, fermented L. edodes hot water extracts by the three LAB showed protective effects, as evident by reduction of the aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase liver markers. The collective results indicate that the fermented L. edodes hot water extracts obtained using LAB are potentially valuable in preventing or treating liver disease.

• The Journal of Engineering Geology
• /
• v.31 no.3
• /
• pp.433-445
• /
• 2021

Plasma blasting by high voltage arc discharge were performed in laboratory-scale soil samples to investigate the fluid penetration efficiency. A plasma blasting device with a large-capacity capacitor and columnar soil samples with a diameter of 80 cm and a height of 60 cm were prepared. Columnar soil samples consist of seven A-samples mixed with sand and silt by ratio of 7:3 and three B-samples by ratio of 9:1. When fluid was injected into A-sample by pressure without plasma blasting, fluid penetrated into soil only near around the borehole, and penetration area ratio was less than 5%. Fluid was injected by plasma blasting with three different discharge energies of 1 kJ, 4 kJ and 9 kJ. When plasma blasting was performed once in the A-samples, penetration area ratios of the fluid were 16-25%. Penetration area ratios were 30-48% when blastings were executed five times consecutively. The largest penetration area by plasma blasting was 9.6 times larger than that by fluid injection by pressure. This indicates that the higher discharge energy of plasma blasting and the more numbers of blasting are, the larger are fluid penetration areas. When five consecutive plasma blasting were carried out in B-sample, fluid penetration area ratios were 33-59%. Penetration areas into B-samples were 1.1-1.4 times larger than those in A-samples when test conditions were the same, indicating that the higher permeability of soil is, the larger is fluid penetration area. The fluid penetration radius was calculated to figure out fluid penetration volume. When the fluid was injected by pressure, the penetration radius was 9 cm. Whereas, the penetration radius was 27-30 cm when blasting were performed 5 times with energy of 9 kJ. The radius increased up to 333% by plasma blasting. All these results indicate that cleaning agent penetrates further and remediation efficiency of contaminated soil will be improved if plasma blasting technology is applied to in situ cleaning of contaminated soil with low permeability.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.63 no.4
• /
• pp.273-281
• /
• 2018

Wet hill seeding (WHS) is one of the more famous labor and money saving methods technology used for rice cultivation. In WHS, rice standing percentage and weedy rice occurrence are the most important factors considered to secure a rice yield. We investigated the optimum seeding date of WHS in the Southern Plain area of South Korea. Weedy rice needed two weeks at $15^{\circ}C$ to show over 80% emergence. Germinated rice seed grown at $20^{\circ}C$ needed over for 10 days to achieve a shoot length over 3 cm. In field cultivation, the mean temperature for ten days after seeding showed a highly positive correlation with rice standing rate, spikelet number per square meter and yield index that favorably compared to machine transplanting. With these data, we suggest that the optimum seeding date of WHS that can secure over 98% of yield index of machine transplanting in Southern part of Korea is May. 21~Jun. 5 in Honam and May. 16~Jun. 5 in Yeongnam area.

• Journal of the Microelectronics and Packaging Society
• /
• v.27 no.4
• /
• pp.83-89
• /
• 2020

For the past few decades, as part of efforts to protect the environment where fossil fuels, which have been a key energy resource for mankind, are becoming increasingly depleted and pollution due to industrial development, ecofriendly secondary batteries, hydrogen generating energy devices, energy storage systems, and many other new energy technologies are being developed. Among them, the lithium-ion battery (LIB) is considered to be a next-generation energy device suitable for application as a large-capacity battery and capable of industrial application due to its high energy density and long lifespan. However, considering the growing battery market such as eco-friendly electric vehicles and drones, it is expected that a large amount of battery waste will spill out from some point due to the end of life. In order to prepare for this situation, development of a process for recovering lithium and various valuable metals from waste batteries is required, and at the same time, a plan to recycle them is socially required. In this study, we introduce a nanoscale pattern transfer printing (NTP) process of Li2CO3, a representative anode material for lithium ion batteries, one of the strategic materials for recycling waste batteries. First, Li2CO3 powder was formed by pressing in a vacuum, and a 3-inch sputter target for very pure Li2CO3 thin film deposition was successfully produced through high-temperature sintering. The target was mounted on a sputtering device, and a well-ordered Li2CO3 line pattern with a width of 250 nm was successfully obtained on the Si substrate using the NTP process. In addition, based on the nTP method, the periodic Li2CO3 line patterns were formed on the surfaces of metal, glass, flexible polymer substrates, and even curved goggles. These results are expected to be applied to the thin films of various functional materials used in battery devices in the future, and is also expected to be particularly helpful in improving the performance of lithium-ion battery devices on various substrates.

• Korean Journal of Environmental Biology
• /
• v.39 no.1
• /
• pp.100-107
• /
• 2021

Along with an increase in the frequency of high-concentration fine particulate matter in Korea, interest and research on ammonia (NH₃) are actively increasing. It is obvious that agriculture has contributed significantly to NH₃ emissions. However, studies on the long-term effect of fertilizer use on the ambient NH₃ concentration of agricultural land are insufficient. Therefore, in this study, NH₃ concentration in the atmosphere of agricultural land was monitored for 11 months using a passive sampler. The average ambient NH₃ concentration during the total study period was 2.02 ㎍ m^-3 and it was found that the effect of fertilizer application on the ambient NH₃ concentration was greatest in the month immediately following fertilizer application (highest ambient NH₃ concentration as 11.36㎍ m^-3). After that, it was expected that the NH₃ volatilization was promoted by increases in summer temperature and the concentration in the atmosphere was expected to increase. However, high NH₃ concentrations in the atmosphere were not observed due to strong rainfall that lasted for a long period. After that, the ambient NH₃ concentration gradually decreased through autumn and winter. In summary, when studying the contribution of fertilizer to the rate of domestic NH₃ emissions, it is necessary to look intensively for at least one month immediately after fertilizer application, and weather information such as precipitation and no-rain days should be considered in the field study.

• Journal of Life Science
• /
• v.32 no.1
• /
• pp.1-10
• /
• 2022

Natural products have gained increasing attention due to their advantage of long-term safety and low toxicity for a very long time. Torreya nucifera is widespread in southern Korea and Jeju Island and its seeds are commonly used as edible food. Oriental ingredients have often been reported for their insecticidal, antioxidant and antibacterial properties, but there have not yet been any studies on their antidiabetic effect. In this study, we investigated several biological activities of T. nucifera pericarp (TNP) and seeds (TNS) extracts and proceeded to characterize the antidiabetic compounds of TNS. The initial results suggested that TNS extract at 15 and 10 ㎍/ml concentration has inhibitory effects on α-glucosidase and protein tyrosine phosphatase 1B, that is 14.5 and 4.35 times higher than TNP, respectively. Thus, the stronger antidiabetic TNS was selected for the subsequent experiments to characterize its active compounds. Ultrafiltration was used to determine the apparent molecular weight of the active compounds, showing 300 kDa or more. Finally the mixture was then partially purified using Diaion HP-20 column chromatography by eluting with 50~100% methanol. Therefore we concluded that the active compounds of TNS have potential as therapeutic agents in functional food or supplemental treatment to improve diabetic diseases.