• Journal of Mushroom
• /
• v.17 no.1
• /
• pp.12-18
• /
• 2019

An auxin-producing bacterium Yangsong-1 was isolated from a button mushroom bed in Chung cheongnam-do. The strain Yangsong-1 was classified as a novel strain of Arthrobacter enclensis based on a chemotaxonomic and phylogenetic analysis. The isolated A. enclensis Yangsong-1 was confirmed to produce indole-3-acetic acid (IAA), which is one of the auxin hormones. When the concentration of IAA was assessed by HPLC quantity analysis, the maximum concentration of IAA, $152.903mg\;L^{-1}$, was detected from the culture broth incubated in R2A medium containing 0.2% L-tryptophan for 48 h at $35^{\circ}C$. A negative relationship between IAA production and pH was estimated to show that the increase in IAA caused pH acidification of the culture. The effect of the supplement on L-tryptophan, a known precursor of IAA production, appeared to be at maximal production at 0.2% concentration and was rather reduced at concentration above 0.4%. To investigate the growth-promoting effects on the crops, the culture broth of A. enclensis Yangsong-1 was placed in water cultures and seed pots of mung beans and lettuce. In consequence, the adventitious root induction and root growth of mung beans and lettuce were 1.5 and 1.9 times higher, respectively, than those of the control.

• Journal of the Korean BIBLIA Society for library and Information Science
• /
• v.30 no.1
• /
• pp.121-143
• /
• 2019

The purpose of this study was to examine the reason and value system of the elderly people on the public library use in Korea. For the purpose, a questionnaire survey was conducted for elderly aged over 60, from 15 public libraries in Seoul from October 29 to October 10, 2018, and 306 valid responses collected were analyzed. The value system is based on the Means-end Chain (MEC) Theory, and the linkage between the attributes, consequences, and values of public library use is figured out as a value hierarchy. As a result, the most frequently revealed value system was 'reads or borrows books (attribute) ${\rightarrow}$ gets new knowledge (consequence) ${\rightarrow}$ satisfies oneself (value).' For the value reached by using the public library, both groups answered that their satisfaction, achievement, fun, pleasure, and vitality. However, the elderly aged 65 and over additionally felt that public libraries are good for their mental / physical health. The results showed that the elderly people using the public library feels the traditional functions of the public library as the main attribute, and the public library could provide the elderly people with contribution to the lively old age.

• Korean Journal of Materials Research
• /
• v.31 no.10
• /
• pp.562-568
• /
• 2021

(Bi_1/2Na_1/2)TiO₃ (BNT)-based ceramics are considered promising candidates for actuator application owing to their excellent electromechanical strain properties However, to obtain large strain properties, there remain several issues such as thermal stability and high operating fields. Therefore, this study investigates a reduction of operating field in (0.98-x)Bi_1/2Na_1/2TiO₃-0.02 BiAlO₃-xSrTiO₃ (BNT-2BA-100xST, x = 0.20, 0.21, 0.22, 0.23, and 0.24) via analyses of the microstructure, crystal structure, dielectric, polarization, ferroelectric and electromechanical strain properties. The average grain size of BNT-${\underline{2}}$BA-100xST ceramics decreases with increasing ST content. Results of polarization and electromechanical strain properties indicate that a ferroelectric to relaxor state transition is induced by ST modification. As a consequence, a large electromechanical strain of 592 pm/V is obtained at a relatively low electric field of 4 kV/mm in 22 mol% ST-modified BNT-2BA ceramics. We believe that the materials synthesized in this study are promising candidates for actuator applications.

• Journal of Environmental Impact Assessment
• /
• v.30 no.4
• /
• pp.215-224
• /
• 2021

In this study, to investigate the effect of stabilization of Pb-contaminated soil near a smelter site for the reduction of environmental risk of Pb leaching, commercial stabilizers were amended with the Pb-contaminated soil and evaluated leaching characteristics of Pb in soil by TCLP and SPLP leaching test. Also, performing sequential extraction procedure speciation of Pb in the amended soil was investigated. Limestone, AC-2 (Amron), Metafix (Peroxychem) that possess stabilization performance towards heavy metal in soil and mass production is available were selected as candidates. AC-2 contained a CaCO₃ and MgO crystalline phase, while Metafix had a Fe₇S₈ crystalline phase, according to XRD studies. Pb content in SPLP extract was lower than the South Korean drinking water standard for Pb in groundwater at 4% AC-2 and Metafix treatment soil, and TCLP-based stabilization effectiveness was more than 90%. The findings of the sequential extraction method of soil treated with Metafix revealed that fractions 1 and 2 of Pb, which correspond to relatively high mobility and bioavailable fractions, were lowered, while the residual fraction (fraction 5) was raised. As a consequence, the order of performance for Pb stabilization in polluted soil was Metafix>AC-2>limestone.

• Journal of Life Science
• /
• v.32 no.11
• /
• pp.841-846
• /
• 2022

The purpose of this study was to evaluate the antioxidant properties of Rosa rugosa extract and to identify which of its components are responsible for these properties. Reactive oxygen species play an important role in diseases such as cancer, arteriosclerosis, and heart disease as a consequence of increased metabolic rates, gene mutations, and relative hypoxia. Therefore, the antioxidant effect of R. rugosa extract was confirmed by HPLC, HPLC-MS/MS, the total polyphenol content, the total flavonoid content, and the radical scavenging activity. HPLC and HPLC-MS/MS analyses were conducted to identify and quantify the main components of the R. rugosa extract. Gallic acid and epigallocatechin gallate were identified as the main components, with 17.4 and 4.35 mg/g dry matter (DM), respectively. The antioxidant activity of R. rugosa extract was evaluated based on its total polyphenol content, total flavonoid content, and radical scavenging activity, which were 72.3 mg gallic acid equivalent/g DM, 11.2 mg quercetin equivalent/g DM, and 87.9%, respectively. The radical scavenging activities of the main components, gallic acid and epigallocatechin gallate, were 80.5% and 89.7%, respectively. Therefore, R. rugosa has a high polyphenol content and antioxidant activity, and it can be used as a natural antioxidant in food, cosmetics, and pharmaceuticals.

• Journal of Korea Water Resources Association
• /
• v.55 no.12
• /
• pp.1077-1089
• /
• 2022

With the construction of Seoul National University (SNU), the Mt. Gwanak watershed has undergone some urbanization. As with other campus catchments, data related to the water cycle is extremely limited. Therefore, this study began by collecting hydrological and meteorological data using Atmos-41, a complex meteorological observation instrument. The observation results of Atmos-41 were validated by analyzing the statistical characteristics and confidence intervals based on the monthly variability of data from the Korea Meteorological Administration. Results of the previous research were used to validate the simulated surface runoff and infiltration using the Storm Water Management Model (SWMM). The potential evapotranspiration (PET) simulated by the SWMM was rectified by comparing it to the Atmos-41 observation data. Multiple regression analysis was employed to adjust for the fluctuations in precipitation, relative humidity, and wind speed because the calculated SWMM PET tends to be underestimated during periods of low temperatures. R² increased from 0.54 to 0.80 when compared to the Atmos-41 PET. The rate of change in the water cycle as a consequence of the SNU's construction resulted in a 15.7% increase in surface runoff, a 14.2% decrease in infiltration rate, and a 1.6% decrease in evaporation.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.50 no.2
• /
• pp.76-88
• /
• 2022

Urban parks play the role of providing leisure spaces for people in their everyday life along with serving ecological functions in the city. Although urban parks aim to satisfy the needs of users visiting the park, most urban parks are currently uniformly created and maintained without considering the environmental characteristics based on the needs of users. This study thus analyzed parks that underwent modifications in line with the revised Park Act in 2005. There were 45 parks whose types were legally changed, of which 21 were changed from children's parks to small parks, and 19 were changed to utilize and highlight the themes such as cultural parks and historical parks. Among the parks whose types have changed, the ratio of amenities in cultural and historic parks has increased, while the facility area in small parks has decreased and the green area has increased in its place. As a result of analyzing the changes to the park facility area, it was confirmed that increasing park amenities has a positive effect in pursuing revitalization of use through park maintenance, but has a negative consequence of significantly decreasing green area. It is necessary to reorganize the park type classification system to reflect the park environment and prepare guidelines for a new installation standard by park type to expand the net function of parks in cities and maintain the sustainable ecological environment. Through in-depth discussions on the facilities of park types, it is anticipated that innovative and multilateral research could be conducted to prepare improvement measures tailored to the guidelines of urban park types in years to come.

• Economic Analysis
• /
• v.27 no.1
• /
• pp.67-90
• /
• 2021

This study found an interesting fact that the nonlinear relationship structure between volatility and trading volume changed before and after the COVID-19 pandemic according to empirical analysis using Bitcoin (BTC) market data that sensitively reflects investors' trading behavior. That is, their relationship appeared positive (+) in a stable market state before COVID-19 pandemic, as in theory based on the information flow paradigm. In a state under severe market stress due to COVID-19 pandemic, however, their dependence structure changed and even negative (-). This can be seen as a consequence of increased market stress caused by COVID-19 pandemics from a behavioral economics perspective, resulting in structural changes in the asset market and a significant impact on the nonlinear dependence of volatility and trading volume (in particular, their dependence at extreme quantiles). Hence, it should be recognized that in addition to information flows, psychological phenomena such as behavioral biases or herd behavior, which are closely related to market stress, can be a key in changing their dependence structure. For empirical analysis, this study performs a test of Ross (2015) for detecting a structural change, and proposes a Copula Regression Quantiles (CRQ) approach that can identify their nonlinear relationship structure and the asymmetric dependence in their distribution tails without the assumption of i.i.d. random variable. In addition, it was confirmed that when the relationship between their extreme values was analyzed by linear models, incorrect results could be derived due to model specification errors.

• Journal of Navigation and Port Research
• /
• v.47 no.1
• /
• pp.25-36
• /
• 2023

To limit greenhouse gas emissions from ships, numerous environmental regulations and standards have been taken into effect. As a result, alternative fuels such as liquefied natural gas (LNG), liquefied petroleum gas (LPG), ammonia, and biofuels have been applied to ships. Most of these alternative fuels are low flashpoint fuels in the form of liquefied gas. Their use is predicted to continue to increase. Thus, management regulations for using low flash point fuel as a ship fuel are required. However, they are currently insufficient. In the case of LNG, ISO standards have been prepared in relation to bunkering. The Society for Gas as a Marine Fuel (SGMF), a non-governmental organization (NGO), has also prepared and published a guideline on LNG bunkering. The classification society also requires safety management areas to be designated according to bunkering methods and procedures for safe bunkering. Therefore, it is necessary to establish a procedure for setting a safety management area according to the type of fuel, environmental conditions, and leakage scenarios and verify it with a numerical method. In this study, as a feasibility study for establishing these procedures, application status and standards of the industry were reviewed. Classification guidelines and existing preceding studies were analyzed and investigated. Based on results of this study, a procedure for establishing a safety management area for bunkering in domestic ports of Korea can be prepared.

• Journal of the Korea Society of Computer and Information
• /
• v.14 no.11
• /
• pp.53-60
• /
• 2009

This paper is focusing on the optimal size of internal space in which various functions are expressed by means of analogizing appropriate size of passage fitted to characters and reverse-calculating it in comparison with preexisting games, and thus increase the objectivity of data. To this end, the work of making the data objective was conducted in advance, and the experiment proceeded in the way that specially-designed Dungeon can make its way through the passage and in the situation where small-scale combats take place. In addition, the efforts were made to standardize the outcome of experiments by restricting the types of game graphics to MMO RPG. Further, the enhance the objectivity of size of the characters, the game types were limited to RPG games, and it is also adjusted to the character's face size based on the graphic designer's preference. The size of shoulders and arms of characters, inter alia, was selected as distinguishing points to be adjusted to the passage. By analyzing these data, the size of passage was re-organized according to the main characters in the MMO RPG games. Four experimental data was utilized by the 200 game experts in order to select the optimal size of passage in the game. As a consequence, the proportional correlation between character and passage movement was evaluated as successful in terms of emotional recognition.