• Geomechanics and Engineering
• /
• v.35 no.4
• /
• pp.437-447
• /
• 2023

The failures of tailing dams have caused irreparable damage to human lives, assets and environment and this has ultimately resulted in great economic, social and environmental challenges worldwide. Due to this, investigation into mechanical behaviour of tailings has received some attention. However, the knowledge and understanding of mechanics of behaviour in iron tailings is still limited. This study investigates the mechanics of iron tailings from Nigeria considering grading, effects of fabric resulting from different sample preparations and the possibility of non-convergent behaviour. This was achieved by conducting series of one-dimensional compression tests in conjunction with index, microstructural, chemical and mineralogical tests. The materials are predominantly poorly graded, non-clayey and non-plastic. The tailings are characterised by angular particles with no obvious particle aggregations and dominated by silicon, iron, aluminium, haematite and quartz. The compression paths do not converge and unique normal compression lines are not found and this is an important feature of the transitional mode of behaviour. The behaviour of these iron tailings therefore depends on initial specific volume. The preparation methods also have effect on the compression paths of the samples. The gradings of the samples have an influence on the degree of transitional behaviour but the preparation methods do affect the degree of convergence. The transitional mode of behaviour in these iron tailings investigated is very strong.

• Journal of Forest and Environmental Science
• /
• v.40 no.1
• /
• pp.64-71
• /
• 2024

Mushroom is very important to rural dwellers due to the various economic, health and nutritional benefits that can be derived from its consumption, sales and utilization. Hence, this experiment was carried out with a view to evaluating the influence of locally available substrate i.e., sawdust of different wood species on the cultivation of Pleurotus ostreatus (oyster mushroom). Pleurotus ostreatus was grown on sawdust (indigenous and exotic species) using two pretreatment methods, which included hot water treatment to remove (a water-soluble extract) and non-extracted sawdusts (substrate). The result of this study showed that there was a significant difference in the effect of different wood species selected. Parkia biglobosa produced a better yield (71.06 g), followed by Anogeissus leiocarpus (53.17 g) and Gmelina arborea (51.39 g) in a non-treated unextracted states. In the treated samples, Parkia biglobosa has the highest yield (50.61 g) followed by Anogeissus leiocarpus (49.28 g) and Gmelina arborea (45.00 g). Thus, Parkia biglobosa and Anogeissus leiocarpus produced a higher yield of mushroom either in a treated or non-treated state and they could be recommended for growing oyster mushroom (Pleurotus ostreatus).

• The Korean Journal of Community Living Science
• /
• v.20 no.1
• /
• pp.71-80
• /
• 2009

This study aimed to identify and compare variables affecting life satisfaction of older women by focusing on household types and poverty levels. The study used data from the Korea Longitudinal Study of Aging administered by the Korea Labor Institute in 2006. The data for 1,017 older women ages over 65 including 427 single households and 590 couple households was analyzed. First, interaction effects of household types and poverty levels on life satisfaction were statistically significant. For the non-poverty households of older women, there was no explicit difference between single households and couple households in life satisfaction, but for the poverty households, single households were lower in life satisfaction than couple households. Second, as a result of reviewing four groups of older women (poverty-single household, poverty-couple household, non-poverty-single household, and non-poverty-couple household), besides religion, it was found that there were significant differences in age, education level, number of children, health level, residence area, and status of economic activity. Third, when analyzing variables affecting life satisfaction, common predictors for the four groups were health level and ownership of house. Older women who perceived to be healthier and owned their own homes were higher in life satisfaction. For poverty-single households, older women with over middle school graduation were also higher in life satisfaction, but for poverty-couple households, older women with over middle school graduation and more children were higher.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.63 no.5
• /
• pp.73-81
• /
• 2021

The objective of this study was to analyze the waste nutrient generation loads from hydroponics for three major crops in Gyeongsangnam-do. Study hydroponic farms were selected for the three major crops such as paprika, strawberry, tomato based on the agricultural statistics data and field investigation. The flow amount and water quality for inflow and outflow of study hydroponic farms were monitored and analyzed on a monthly basis. Monitored samples were analyzed in terms of DO, BOD, T-N, T-P, SS, and EC. The generated load of BOD, T-N, and T-P were calculated from the monitored flow and water quality. The monitoring results showed that the drainage ratio for the circular hydroponic farm was lower than the non-circular hydroponic farm because the outflow from the circular hydroponics were much lower than that from the non-circular. The generated load calculation results showed that the BOD tended to have a smaller value than the TMDLs guideline for land, while T-N and T-P showed higher value than that from the TMDLs guideline. In order to effectively manage the pollutant load discharged from the hydroponics farming complex, it is necessary to manage the non-circulating hydroponics farm. To improve water quality, it is necessary to gradually expand the circulating hydroponics farm through policy and economic support.

• Communications for Statistical Applications and Methods
• /
• v.28 no.5
• /
• pp.447-462
• /
• 2021

In insurance, the surrender rate is an important variable that threatens the sustainability of insurers and determines the profitability of the contract. Unlike other actuarial assumptions that determine the cash flow of an insurance contract, however, it is characterized by endogenous variables such as people's economic, social, and subjective decisions. Therefore, a microscopic approach is required to identify and analyze the factors that determine the lapse rate. Specifically, micro-level characteristics including the individual, demographic, microeconomic, and household characteristics of policyholders are necessary for the analysis. In this study, we select panel survey data of Korean Retirement Income Study (KReIS) with many diverse dimensions to determine which variables have a decisive effect on the lapse and apply the lasso regularized regression model to analyze it empirically. As the data contain many missing values, they are imputed using the random forest method. Among the household variables, we find that the non-existence of old dependents, the existence of young dependents, and employed family members increase the surrender rate. Among the individual variables, divorce, non-urban residential areas, apartment type of housing, non-ownership of homes, and bad relationship with siblings increase the lapse rate. Finally, among the financial variables, low income, low expenditure, the existence of children that incur child care expenditure, not expecting to bequest from spouse, not holding public health insurance, and expecting to benefit from a retirement pension increase the lapse rate. Some of these findings are consistent with those in the literature.

• Earthquakes and Structures
• /
• v.6 no.5
• /
• pp.515-537
• /
• 2014

Current seismic codes (e.g. the NTC08 Italian code and the EC8 European code) adopt a performance-based approach for both the design of new buildings and the assessment of existing ones. Different limit states are considered by verifying structural members as well as non structural elements and facilities which have generally been neglected in practice. The key role of non structural elements on building performance has been shown by recent earthquakes (e.g. L'Aquila 2009) where, due to the extensive damage suffered by infills, partitions and ceilings, a lot of private and public buildings became unusable with consequent significant socio-economic effects. Furthermore, the collapse of infill panels, particularly in the case of out-of-plane failure, represented a serious source of risk to life safety. This paper puts forward an infill model capable of accounting for the effects arising from prior in-plane damage on the out-of-plane capacity of infill panels. It permits an assessment of the seismic performance of existing RC buildings with reference to both structural and non structural elements, as well as of their mutual interaction. The model is applied to a building type with RC framed structure designed only to vertical loads and representative of typical Italian buildings. The influence of infill on building performance and the role of the out-of-plane response on structural response are also discussed.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.37 no.5
• /
• pp.351-357
• /
• 2019

UAV (Unmanned Aerial Vehicle) images can be exploited for rapid forest fire damage assessment by virtue of UAV systems' advantages. In 2019, catastrophic forest fire occurred in Goseong and Sokcho, Korea and burned 1,757 hectares of forests. We visited the town in Goseong where suffered the most severe damage and conducted UAV flights for forest fire damage assessment. In this study, economic and rapid damage assessment method for forest fire has been proposed using UAV systems equipped with only a RGB sensor. First, forest masking was performed using automatic elevation thresholding to extract forest area. Then ExG (Excess Green) vegetation index which can be calculated without near-infrared band was adopted to extract damaged forests. In addition, entropy filtering was applied to ExG for better differentiation between damaged and non-damaged forest. We could confirm that the proposed forest masking can screen out non-forest land covers such as bare soil, agriculture lands, and artificial objects. In addition, entropy filtering enhanced the ExG homogeneity difference between damaged and non-damaged forests. The automatically detected damaged forests of the proposed method showed high accuracy of 87%.

• Journal of Korea Planning Association
• /
• v.54 no.7
• /
• pp.89-102
• /
• 2019

The growth of vacant housing has been problematic in both Korea and other countries as it causes various socio-economic problems and negatively affects residential environments. Despite the importance of effectively managing vacant housing, few studies have been undertaken regarding spatial patterns of vacant housing growth. This study aims to examine spatial dependence in vacant housing growth. We used 2005 and 2015 Population and Housing Census and employed spatial modeling. The empirical analysis shows that there is spatial dependence in vacant housing growth. Also, the spatial clusters of growing vacant housing are present in the non-capital region and nearby cities while the spatial clusters of declining vacant housing are present in the capital region. The policy implications of this study are as follows: First, local governments should make collaborate efforts with geographically proximate cities for more effective management of vacant housing. Second, given that vacant housing is more prevalent and growing in the non-capital region, it is necessary to employ differential policies to manage housing vacancy between the capital and non-capital regions.

• Earthquakes and Structures
• /
• v.10 no.2
• /
• pp.429-450
• /
• 2016

An attempt has been made to incorporate the concept of collapse safety margin into the procedures proposed in the performance-based earthquake engineering (PBEE) framework for direct earthquake loss estimation, in which the collapse probability curve obtained from incremental dynamic analysis (IDA) is mathematically characterized with the S-type fitting model. The regressive collapse probability curve is then used to identify non-collapse cases and collapse cases. With the assumed lognormal probability distribution for non-collapse damage indexes, the expected direct earthquake loss ratio is calculated from the weighted average over several damage states for non-collapse cases. Collapse safety margin is shown to be strongly related with sustained damage endurance of structures. Such endurance exhibits a strong link with expected direct earthquake loss. The results from the case study on three concrete frames indicate that increase in cross section cannot always achieve a more desirable output of collapse safety margin and less direct earthquake loss. It is a more effective way to acquire wider collapse safety margin and less direct earthquake loss through proper enhancement of reinforcement in structural components. Interestingly, total expected direct earthquake loss ratio seems to be insensitive a change in cross section. It has demonstrated a consistent correlation with collapse safety margin. The results also indicates that, if direct economic loss is seriously concerned, it is of much significance to reduce the probability of occurrence of moderate and even severe damage, as well as the probability of structural collapse.

• Health Policy and Management
• /
• v.27 no.3
• /
• pp.191-198
• /
• 2017

Moon Jae-in Government announced the Government's 5-Year Plan on July 19, 2017, President Moon directly announced the Government's Plan for Benefit Expansion in National Health Insurance on August 7, 2017. The main contents of the announced expansion include benefit coverage for all medically necessary services with control over non-covered service occurrence, a decrease in the cost-sharing upper limit, and monetary support for catastrophic medical costs. Although past governments have been continuously striving for benefit expansion in the last 15 years, this plan has its breakthrough aspect in that all medical services will be covered by the National Health Insurance. In alignment, there are important tasks to solve: attaining a proper fee schedule, reforming the healthcare delivery system, and improving healthcare quality. This plan is a symptom oriented action in that it is limited in reducing patients' out-of-pocket money, unlike the systematic approach of the National Health Insurance. The sustainability of the National Health Insurance is being threatened due to South Korea's low birth rate, rapidly aging society, and low economic growth, in addition to the unification issue of the Korean Peninsula, medical utilization of the elderly, management of non-communicable diseases, and so on. Therefore, the Government needs to plan the National Health Insurance system reformation including actions addressed toward medical consumers.