• Journal of Korean Society of Forest Science
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• v.35 no.1
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• pp.15-18
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• 1977

In order to investigate reproductive capacity of genus Lespedeza 5 spp.; L. bicolor, L. maximowiczii, L. japonica var. intermedia, L. angustifolioides, and L. cyrtobotrya, their hights, diameter at the ground level, and the number of sprouts were compared with each other at the end of October during investigating years from 1970 to 1976. For measuring of invested items, 6 stocks which the one-year aged stem were cut above ground were randomly planted per square meter with six replications at the spring of 1970. After hights, diameter, and the number of sprouts were measured at the end of October every year, the stem were cut above ground at the end of November from 1970 to 1976. The results are as follows: 1. The reproductive of the stems showed statistiaclly significant differences at 1% level by species and stock ages. L. bicolor showed the best reproductive capacity of them. 2. The sprouting ability was revealed that L. maximowiczii showed the best of them. 3. The reproductive capacity of stem, diameter, and number of sprouts increased with aging of stock up to 5 years on the investigated 5 species.

• The Journal of the Convergence on Culture Technology
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• v.6 no.2
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• pp.535-541
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• 2020

A conventional elastic material replacement and performance evaluation are very complicated and time-consuming, and it is difficult to know when to replace the elastic material in advance. By comparing with the product limit and the functional limit, the necessity of elastic material replacement and the improvement of track support stiffness according to replacement can be immediately demonstrated based on experimental data. Using an evaluation system of track support stiffness, the performance evaluation data for elastic materials obtained through field tests using software for track support stiffness is integrated and managed on the administrator's computer. Therefore, the replacement plan is established and maintenance history is managed by identifying the replacement time and location of elastic materials. It is possible to evaluate the performance and condition of the elastic material at the various points during the working time of the track inspection and the track performance (track support stiffness) and durability of the elastic material (aging level, spring stiffness variation rate, etc.) at the operation condition. The elastic material could be replaced timely, and the deterioration of the elastic material can be continuously monitored.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.5 no.1
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• pp.28-35
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• 1994

Research on biological aspects on adult depression has been subjected to more than 25 years of systematic research, while biologic investigations regarding childhood and adolescent depression are only now being initiated. Although no unifying, explanatory theory of the biologic etiology of childhood depression emerges from the results of studies reviewed above, the findings do support that biological factors may be involved in the genesis of childhood depression. The research reviewed in this paper suggests that age and pubertal factors have major effects in most biological markers of depression. Some of these markers, like sleep EEG and neuroendocrine markers should be broken down by decades during adult life span. Thus, although adult data are very valuable points of departure for biological research on child and adolescent depression, it is very hard to transfer the adult data to prepubertal children and adolescents, ignoring the biological changes that take place in growth and development, pubety and aging. A great deal of work in basic developmental neuroscience remains to be done. It will be crucial for further advances in this field to determine the normal patterns of neurotransmitter interaction in this age group and to study children at high risk for depression. It will be also crucial to use primate models of depressive illness in order to be able to answer the many queations that cannot be investigated in humans for ethical issues. Conclusively, much closer collaboration between developmental and neurobiological and behavioral studies in primates and in humans will be essential for further development.

• Journal of Dental Anesthesia and Pain Medicine
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• v.16 no.1
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• pp.39-47
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• 2016

Background: Oxidative stress occurs during the aging process and other conditions such as bone fracture, bone diseases, and osteoporosis, but the role of oxidative stress in bone remodeling is unknown. Propofol exerts antioxidant effects, but the mechanisms of propofol preconditioning on oxidative stress have not been fully explained. Therefore, the aim of this study was to evaluate the protective effects of propofol against $H_2O_2$-induced oxidative stress on a human fetal osteoblast (hFOB) cell line via activation of autophagy. Methods: Cells were randomly divided into the following groups: control cells were incubated in normoxia (5% $CO_2$, 21% $O_2$, and 74% $N_2$) without propofol. Hydrogen peroxide ($H_2O_2$) group cells were exposed to $H_2O_2\;(200{\mu}M)$ for 2 h, propofol preconditioning (PPC)/$H_2O_2$ group cells were pretreated with propofol then exposed to $H_2O_2$, 3-methyladenine (3-MA)/PPC/$H_2O_2$ cells were pretreated with 3-MA (1 mM) and propofol, then were exposed to $H_2O_2$. Cell viability and apoptosis were evaluated. Osteoblast maturation was determined by assaying bone nodular mineralization. Expression levels of bone related proteins were determined by western blot. Results: Cell viability and bone nodular mineralization were decreased significantly by $H_2O_2$, and this effect was rescued by propofol preconditioning. Propofol preconditioning effectively decreased $H_2O_2$-induced hFOB cell apoptosis. However, pretreatment with 3-MA inhibited the protective effect of propofol. In western blot analysis, propofol preconditioning increased protein levels of collagen type I, BMP-2, osterix, and TGF-${\beta}1$. Conclusions: This study suggests that propofol preconditioning has a protective effect on $H_2O_2$-induced hFOB cell death, which is mediated by autophagy activation.

• Journal of the Korean Geographical Society
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• v.51 no.6
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• pp.837-851
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• 2016

The growth and development of Gwangyang city was a result of the POSCO Gwangyang Works, and Gwangyang city is one of typical firm citys in Korea. The objective of this study is to identify and examine the change of migration and population structure in Gwangyang city from 2001 to 2010. Since 1981, total number of population of Gwangyang city increased from 78,478 in 1981 to 145,512 in 2010. The population structure by age was changed with population increase since 2001, and 30-40 aging group was 35% of total in 2010. During 2001-2010, the netmigraion showed -2,925 people, however, the number of inmigrants were overtaking the number of out-migrants since 2008. The most common reason of in-migrants was occupation(49.5%). Factors influencing Gwangyang City's population growth and oversupply are the location of POSCO Gwangyang Works and steel-related enterprises, opening and construction of Gwangyang container berth, the related development projects and establishment of Gwangyang Bay Area Free Economic Zone, and the local policies of Gwangyang City connected with these large-scale national projects. As a result, the number of manufacturing-related businesses increased due to various regional development projects conducted in Gwangyang City, and the growth of the business continued to increase due to the increase of younger people and births.

• Journal of the Korean Magnetics Society
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• v.22 no.5
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• pp.167-172
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• 2012

In order to analyze the formation mechanism of iron oxide nanoparticles, we measured the heat flow of $Fe(OL)_3$ precursor with temperature, and TEM images and AC susceptibility of aliquots samples sequentially taken from the reaction solution, respectively. The thermal decomposition of two OL-chain from $Fe(OL)_3$ produced the Fe-OL monomer, which were contributed to the formation of iron oxide nanoparticles. In the initial stage of nanoparticles formation, the small iron oxide nanoparticles had ${\gamma}-Fe_2O_3$ structure. However, as the iron oxide nanoparticles were rapidly growth, the iron oxide nanoparticles showed ${\gamma}-Fe_2O_3$-FeO core-shell structure which the FeO layer was formed on the surface of ${\gamma}-Fe_2O_3$ nanoparticles by insufficient oxygen supply from the reaction solution. These nanoparticles were transformed to $Fe_3O_4$ structure by oxidation during long aging time at high temperature. Finally, the $Fe_3O_4$ nanoparticles with high saturation magnetization and stable in the air could be easily synthesized by the thermal decomposition method.

• Korean Journal of Agricultural Science
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• v.24 no.2
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• pp.132-137
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• 1997

Effective storage facilities are required to stabilize the price of agricultural and marine products to preserve their qualities due to the big fluctuation of shrimp price in Korea. It is easy to make the cave because of good conditions of the land configuration, soil and convenient transportation. The cave storage can save the cost about 40% in building site and equipment, and about 50% in maintenance comparing to existing low temperature storage facilities. The cave storage provide to improve the quality of their stored products with the low heat conductivity, the constant temperature and humidity year round. Therefore, more low temperature storage facilities are required because the items are expanded from potatoes, sweet potatoes, onions, garlics, apples and chestnuts to tangerines, grapes, cabbages, radishes, and wet ginsengs. The demands of the low temperature storage facilities can be substituted into the cave storage facilities. Thus, studies are conducted to observe the changes of the components of the pure and the seasoned salted shrimps with fermentation period during stored at room temperature in cave and to establish the storing at underground facilities to produce high quality salted fish to make profit.

• Nuclear Engineering and Technology
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• v.20 no.2
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• pp.88-104
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• 1988

The FUel Rod Analysis(FURA) code is developed using two-dimensional finite element methods for axisymmetric and plane stress analysis of fuel rod. It predicts the thermal and mechanical behavior of fuel rod during normal and load follow operations. To evaluate the exact temperature distribution and the inner gas pressure, the radial deformation of pellet and clad, the fission gas release are considered over the full-length of fuel rod. The thermal element equation is derived using Galerkin's techniques. The displacement element equation is derived using the principle of virtual works. The mechanical analysis can accommodate various components of strain: elastic, plastic, creep and thermal strain as well as strain due to swelling, relocation and densification. The 4-node quadratic isoparametric elements are adopted, and the geometric model is confined to a half-pellet-height region with the assumption that pellet-pellet interaction is symmetrical. The pellet cracking and crack healing, pellet-cladding interaction are modelled. The Newton-Raphson iteration with an implicit algorithm is applied to perform the analysis of non-linear material behavior accurately and stably. The pellet and cladding model has been compared with both analytical solutions and experimental results. The observed and predicted results are in good agreement. The general behavior of fuel rod is calculated by axisymmetric system and the cladding behavior against radial crack is used by plane stress system. The sensitivity of strain aging of PWR fuel cladding tube due to load following is evaluated in terms of linear power, load cycle frequency and amplitude.

• Korea journal of population studies
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• v.28 no.2
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• pp.219-243
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• 2005

This paper reviews research outputs in Korea Journal of Population Studies (KJPS) and the changes in their contents during the period of 1977-2004. In the early years of KJPS, various types of outputs were published, but changes have been made into a direction that research articles compose the main context of the journal. As the journal published twice a year, the total number of articles of the journal shows a trend of marked rise. An analysis of the themes of articles shows that the trend of research in Korean demography has changed hand in hand with transformations of the Korean society. The traditional topics such as population policy, fertility, mortality, and migration were popular before. Labor force, nuptiality, family, aging, regional studies are found to be more popular themes of research recently. Reflecting academic and social demands, KJPS has a broaden range of authors, such as professor, researcher, a government employee, post-doc, and graduate students. The articles written by those working in universities have increased continuously, while research outputs of research institutes have decreased recently. The data for analysis used in articles are varied from but concentrated in some materials - census, vital statistics and various survey data. In early years of KJPS, relatively simple techniques of analysis were adopted in the majority of articles. However, more sophisticated techniques including applied regression analysis, logistic analysis and analysis of survival ratio turn out to be more popular recently. Finally, several suggestions for the future research are presented in this paper.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.39 no.2
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• pp.149-158
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• 2013

L-ascorbic acid, the representative antioxidants, has a great effect on skin whitening, collagen synthesis, and anti-aging, but has low oxidative stability during storage. Therefore, in this study, thermal and oxidation properties of L-ascorbic acid under various storage conditions (powder, aqueous phase, changes of temperature, UV-irradiation, and inflow of external air etc.) were investigated. And the storage stability of ingredient was validated in the double-spaced pouch by analysing oxidation properties under each storage conditions (powder phase and blended with essence). In oder to analyze the thermal properties, TGA, DSC, and FT-IR analysis were carried out and UV-visible spectrophotometer & redox titration were used in parallel for oxidation property analyses. From the result of experiment, L-ascorbic acid was oxidized fast when it contained lots of metallic ion, hydroxy ion in aqueous solution under high temperature, UV-irradiation & inflow external air, whereas it was not oxidized for a long time when it was stored as pure powder although it has same condition as heating up, UV-irradiation & inflow external air. Based on this result, retention period of cosmetics which is using L-ascorbic acid, less stable material in oxidation can be innovatively increased when using double-spaced pouch that is designed and produced for separating storage of active ingredients.