• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.6
• /
• pp.68-79
• /
• 2018

An examination of the characteristics of the ground material in is very important in a ground investigation. Casagrande classified soil using the material properties of soils. The liquid-plastic limit test is useful for obtaining basic information of soil, and is an effective method for classifying silt and clay, as well as the material properties, such as shear strength, shrinkage, and expansion. Unlike the liquid limit test, the plasticity limit test is due to the ambiguity of the test procedure. Many geotechnical engineers and scholars have questioned the test results. In this study, a new plasticity limit method was used to compare with the thread rolling method with kaolinite, ilite and bentonite at a certain ratio, and samples were collected from the west coast of Korea. As a result of the comparison, the test value of the new test method showed high reproducibility because the error range of the test value of the conventional thread rolling test was only 10% but the error range of the new test values decreased to 2%. The difference in the slope of the existing plasticity test values was 0.1519 ~ 0.1925, and the results of the test were similar or coincided with each other. Aone - point method was proposed to make it easier to apply the new test method.

• Economic and Environmental Geology
• /
• v.36 no.5
• /
• pp.339-347
• /
• 2003

Using 171 groundwater chemistry data, seawater intrusion in the Ulsan area was studied. The area near the downstream area of the Taehwa River shows the higher Cl concentrations(11,300 mg/L in maximum), whereas the Cl concentrations are generally low in the eastern coastal area maybe due to the geology of the area. When Cl concentrations are very low, groundwater shows Br:Cl weight ratios significantly deviating from the Br:Cl ratio of seawater($34.7{\times}10^{-4}$). However, Br:Cl ratios are very close to the value of seawater when Cl concentrations are higher than 100 mg/L. Eleven groundwater samples having very high Cl concentrations(>500 mg/L) show that ionic ratios for Ca, Mg, $SO_4$, $HCO_3$ and $SiO_2$ are considerably different from those of seawater. This indicates that the origin of the high Cl groundwaters occurring along the Taehwa River are likely to be the residual salines from the salterns previously located on the alluviums rather than the seawaters intruded recently. These waters seem to be accumulated in the sediments before the drastic expansion of the city. Considering the characteristics of the urban groundwater system where the inflow exceeds the outflow, it is anticipated that the high Cl concentration in the groundwater show a decreasing trend in the future.

• Journal of the Korean Society for Library and Information Science
• /
• v.48 no.1
• /
• pp.27-52
• /
• 2014

The employment prospects of graduates in the Library and Information academic has largely concentrated in the field of librarianship as well as the curriculum of the academic itself. Since there are limitations in increasing the number of libraries and the available posts in the librarianship, the full-time jobs in the field are also limited. Even for the available posts in the field of librarianship, the majority is in contract based posts which does not guarantee a good working environment. The purpose of this research is to make policy implications to improve the employment rates of librarians. The main research methods include literature review of the previous studies and available statistical data, and a questionnaire targeting students and librarians. The targeting policy implications can be categorized into 4 factors, including, as supply side, improvements in the qualification of librarian certificate, in training for librarians, and as demand side, laws on library employment, and improvement of library services for co-operatives. There are 15 detailed strategies to support the 4 factors. For the improvement of strategies in library related laws, the following elements will be considered; supporting system for temporary jobs, the title of librarian post and the library itself, and librarian placement criteria in terms of its realization and mandatory, and obligations in library evaluation. The Council discussions propose the expansion of librarian award system, provision of information systems for librarian jobs, and developments in promotional materials and their deployment for librarians.

• Journal of the Korean Society of Tobacco Science
• /
• v.15 no.1
• /
• pp.63-74
• /
• 1993

Changes in the amount of ribulose 1, 5-bisphosphate carboxylase/oygenase(=RuBisCO) protein, namely fraction I protein, and the protease activity were determined in the 10th leaf of tobacco(Nicotiana tabacum, var. Ky-57) from 10 days after emergence through senescence at 5 days interval. The amount of RuBisCO per deveined leaf rapidly increased during the early growing season, reached a maximal quantity at the around 20 days after leaf emergence, when the leaf has gone through its most rapid expansion, and began gradually to decrease till 30 days after leaf emergence, thereafter significantly declined to 45 days that the leaf has been dried up partly. The pattern of the ratio of RuBisCO protein to soluble protein in quantity changed similar to that of RuBisCO contents in a leaf, that was 43%, 60%, and 21% at the around 10 days, 20 days, and 45 days, respectively. And RuBisCO contents was linearly correlated with the concentration of chlorophyll(r=0.98) throughout the life span of the leaf. So, it was assumed that the leaf color can be a useful indicator for judging whether RuBisCO contents higher or not in tobacco leaves without homogenization. On the other hand, the protease activities for degradation of casein were assayed at pH 5.5. 7.0. and 8.5 with crude extracts desalted on Sephadex G-25. The highest caseolytic activity was found at pH 5.5 throughout the life sawn of the leaf. Also, the activity at 5.5 became gradually to increase from 30 days after leaf emergence, when RuBisCO protein had became to disappear and remarkably increased in the last stage of senescence, although nitrogen contents of the leaf had reached low levels. The caseolytic activity at pH 5.5 was in negative correlation with RuBisCO contents throughout the life span of the leaf, but not in lineality between them. In other words, the caseolytic activity increased in a rapid exponential manner when RuBisCO contents had reached some low levels. These results showed that the leaf age, namely harvesting time, is a very important factor for the production of the tobacco leaf containing higher RuBisCO protein. It was concluded that the practical harvesting time is between 20 days and 30 days after the leaf emergence from the present results.

• Applied Chemistry for Engineering
• /
• v.18 no.5
• /
• pp.522-526
• /
• 2007

Structural features and electrochemical performances of cokes pyrolized from oxidized cokes were examined, and compared with KOH-activated coke. Needle cokes ($d_{002}=3.5{\AA} $), having a graphene layer structure, were changed to a single phase of graphite oxide after oxidation treatment with an acidic solution having an $NaCLO_3$/needle coke composition ratio of above 7.5, and the inter-layer distance of the oxidized coke was expanded to $6.9{\AA} $ with increasing oxygen content. After heating at $200^{\circ}C$, the oxidized coke was pyrolized to the graphene layer structure with inter-layer distance of $3.6{\AA} $. However, the change of the inter-layer distance of the needle coke was not observed in the KOH activation process. On the other hand, an intercalation of electrolyte ions into the pyrolized coke, observed at first charge, occurred at 1.0 V, in which the value was lower than that of KOH-activation coke. The cell capacitor using pyrolized coke exhibited a lower internal resistance of $0.57{\Omega}$ in 1 kHz, and a larger capacitance per weight and volume of 30.3 F/g and 26.9 F/ml at the two-electrode system in the potential range 0~2.5 V than those of the cell capacitor using KOH-activation of coke. This better electrochemical performance may be associated with structure defects in the graphene layer derived from the process of the inter-layer expansion and shrinkage.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.4
• /
• pp.464-473
• /
• 2016

The air temperatures of the coast and inland are rising due to an increase in carbon dioxide emissions and abnormal climate phenomena caused by global warming, El Nino, La Nina and so on. The sea levels of the Earth are rising by approximately 2.0 mm per year (global average value) due to the thermal expansion of sea water, melting of glaciers and other causes by global warming. On the other hand, when it comes to designing a hydraulic structure or coastal hydraulic structure, the standard of the design water level is decided by analyzing four largeness tide values and a harmonic constant with the observed tidal water level or simulating numerical model. Therefore, the design tidal water level needs to consider an increasing speed of the seawater level, which corresponds to the design frequency. In the present study, the observed tidal water levels targeting 46 tidal stations operated by the Korea Hydrographic and Oceanographic Administration (KHOA) from the beginning of observations to 2015 per hour were collected. The variation of the monthly and yearly and increasing ratio were performed and divided into 7 seas, such as east and west part of the Southern Sea, south part and middle of the East Sea, south part and middle of the Western Sea, and Jeju Sea. The current study could be used to determine the cause of local seawater rises and reflect the design tidal water level as basic data.

• The Korean Journal of Food And Nutrition
• /
• v.28 no.6
• /
• pp.995-1003
• /
• 2015

This study was to investigate the association among satisfaction of nutrition labeling, change of purchase behaviors, and dietary life care, based on the awareness of nutrition labeling at expressway rest areas. The subjects (n=903) were divided into two groups, according to the awareness of nutrition labeling: Awareness of Nutrition Labeling (ANL) group, n=367; Non Awareness of Nutrition Labeling (NANL) group, n=536. Effort of health care and identification of nutrition labeling was significantly higher in the ANL group, compared with the NANL group. As for the main reason for not identifying nutrition labeling, 'not interested in nutrition labeling' was the highest in the ANL group, and 'Don't know nutrition labeling is provided' in the NANL group. Identification ratio of nutrition labeling in future was significantly higher in the NANL group, compared with the ANL group among the subjects who didn't identify nutrition labeling before. After their becoming aware, a change of food purchase after reading the nutrition labeling was significantly higher in the ANL group, compared with the NANL group. Health beliefs on the nutrition labeling were significantly higher in the ANL group, compared with the NANL group. Satisfaction of nutrition labeling was also significantly higher in the ANL group, compared with the NANL group. The ANL group also expressed a necessity of expansion of nutrition labeling, compared with the NANL group. In the ANL group, identification of nutrition labeling was significantly higher in the hard effort group, compared with the little effort group of dietary life care. Therefore, improvement and campaign of nutrition labeling for consumers at expressway rest areas, especially for the NANL group, will be effective in identifying nutrition labeling for their health care.

• Korea journal of population studies
• /
• v.29 no.1
• /
• pp.25-56
• /
• 2006

This study attempts to review the increasing trend in international marriage of Koreans since 1990 and explore the pattern of socio-demographic characteristics of the married couples. This paper develops a conceptual scheme for changing pattern of nuptiality including an increase in international marriage. As the key forces behind the recent increase in international marriage of Koreans, the effects of rapid decline in fertility, rise in sex ratio at birth, urbanward migration of young women, expansion of gender-equity norms, and globalization are stressed. Micro-data from the marriage registration for the period $1990{\sim}2004$ and the divorce registration for the period $2000{\sim}2004$ are utilized. This study focuses on analyzing age at marriage, previous marital experience, education, occupation, and residence of the married couples. Attention is also focused on demographic characteristics of the divorced couples. Results of analyses reveal that there exists a great deal of diversity in international marriage of Koreans. A notable aspect is the profound differences between Korean men and women in the characteristics of their foreign spouses and themselves as well. Another prominent factor emphasized in the analysis is the nationality of foreign spouse. It is indicated that the stereotype of international marriage facilitated by marriage squeeze can be mainly applied to marriages between Korean men and foreign wives from China, southeast Asian countries and the CIS of the old Soviet Union. On the other hand, direct effects of value transformation and globalization are emphasized in the explanation of marriages between Korean men and foreign wives from more developed countries as well as marriages between Korean women and foreign husbands.

• Korean Journal of Materials Research
• /
• v.8 no.6
• /
• pp.505-512
• /
• 1998

In this study, two-layer thermal barrier coatings composed of plasma sprayed 0.3mm $ZrO_2(8wt% Y_2o_3)$ ceramic coating layer and O.lmm $NiCrAlCoY_20_3$ bond coating layer on AISI 316 were investigated microstructure of the coating, oxidation of the metallic bond coating and adhesive strength to evaluate the durability of coating layer after cyclic and isothermal test at 90$0^{\circ}C$. And quantitative phase analysis of $ZrO_2(8wt% Y_2o_3)$ ceramic coating was performed as a function of thermal exposure time using XRD technique. The results showed that the amount of m - 2rO, phase in the coating was slightly increased with increasing thermal exposure time at 90$0^{\circ}C$. The c/a ratio of t' - $ZrO_2$ in the as-sprayed coating was 1.0099 and slightly increased to 1.0115 after 100 hours heat treatment. It was believed that $Y_2O_3$ in high yttria tetragonaJ(t') was transformed to low yttria tetragonaJ(t) by $Y_2O_3$ diffusion with increasing thermal exposure time. The adhesive strength was gradually decreased as thermal exposure time increased. After the isothermal test, the failure predominantly occured in ceramic coating layer. On the other hand. the specimens after cyclic thermal test were mostly failed at bond coating/ceramic coating interface. The failure was oeeured by decreasing the bond strength between bond coating and oxide scale which were formed by oxidation of the metallic elements within bond coating and by thermal stress due to thermal expansion mismatches between the oxide scale and ceramic coating.

• Journal of the Korea Concrete Institute
• /
• v.24 no.3
• /
• pp.305-313
• /
• 2012

Unreinforced masonry buildings represent a significant portion of the existing and historical buildings around the world. Recent earthquakes have shown the need for seismic retrofitting for these types of buildings. Various types of retrofitting materials (i.e., shotcrete, ECC and Fiber Reinforced Polymer sheets (FRPs)) for unreinforced masonry buildings (URM) have been developed. Engineers prefer to use FRPs, because these materials enhance the shear strength of the wall without expansion of wall sectional area and adding weight to the total structure. However, the complexity of the mechanical behavior of the masonry wall and the lack of experimental data from walls retrofitted by FRPs may cause problems for engineers to determine an appropriate retrofitting level. This paper investigate in-plane behavior of URM and retrofitted masonry walls using two different types of FRP materials to determine and provide information for the retrofitting effect of FRPs on masonry shear walls. Specimens were designed to idealize the wall of a low-rise apartment which was built in 1970s in Korea with no seismic reinforcements with an aspect ratio of 1. Retrofitting materials were carbon FRP and Hybrid sheets which have different elastic modulus and ultimate strain capacities. Consequently, this study evaluated the structural capacity of masonry shear walls and the retrofitting effect of an FRP sheet for in-plane behavior. Also, the results were compared to the results obtained from the evaluation method for a reinforced concrete beam retrofitted with FRPs.