• Economic and Environmental Geology
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• v.56 no.4
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• pp.409-419
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• 2023

Acid mine drainage(AMD) treatment is classified as both passive and active treatment. During the treatment, about 5,000 tons of neutralization sludge is generated as a by-product per year in Korea. This study was conducted to evaluate the characteristics of sludge generated from physico·chemical treatment processes as an active treatment from 5 different sources (D, H, S, T, Y) and the possibility of the sludges being recycled. The sludges have a pH range of 5.86 ~ pH 7.89, and a water content range of 51% ~ 82%. Most of particle sizes were less than 25 ㎛. In analysis of inorganic elements, the concentration of Al, Fe, and Mn were between 1,189 mg/kg ~ 129,344 mg/kg, 106,132 mg/kg ~ 338,011 mg/kg, and 3,472 mg/kg ~ 11,743 mg/kg, respectively. The concentration of As and Zn in sludge-T, Cd in sludge-D, Ni in sludge-H, Zn in sludge-S, and Cd in sludge-Y exceeded the soil contamination standards of Korea. The results from 2 separate kinds of leaching test, the Korea Standard Leaching Test(KSLT) and Toxicity Characteristic Leaching Procedure(TCLP), showed that all the sludges met the Korea groundwater standards. From the XRD and SEM-EDS analysis, the peaks of calcite and quartz were found in the sludges. The sludge also had a high proportion of Fe and O, and the majority of the composition was amorphous iron hydroxide.

• Journal of Digital Convergence
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• v.20 no.3
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• pp.343-348
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• 2022

Recently, With the recent rapid development of technology, the amount of data generated by various systems is increasing, and enterprise servers and data centers that have to handle large amounts of big data need to apply high-stability and high-performance storage devices even if costs increase. In such systems, SSD(solid state disk) that provide high performance of read/write are often used as storage devices. However, due to the characteristics of reading and writing on a page-by-page basis, erasing operations on a block basis, and erassing-before-writing, there is a problem that performance is degraded when duplicate writes occur. Therefore, in order to delay this performance degradation problem, over-provision technology of SSD has been applied internally. However, since over-provided technologies have the disadvantage of consuming a lot of storage space instead of performance, the application of inefficient technologies above the right performance has a problem of over-costing. In this paper, we proposed a method of measuring the performance and cost incurred when various over-provisions are applied in an SSD and predicting the system-optimized over-provided ratio based on this. Through this research, we expect to find a trade-off with costs to meet the performance requirements in systems that process big data.

• Journal of the Korean Society for information Management
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• v.39 no.4
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• pp.99-125
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• 2022

In order to understand a record, not only the contents of the record but also the production background and work context of the record must be grasped. It also requires a function that makes it easy to find related records scattered across various departments and agencies. Accordingly, the 'linkage' of information in archival information services is becoming more important. NAK also emphasizes 'linkage' as a search service function of the archives management system, but some problems were identified at the National Archives Portal Service (NAPS) such as a lack of linkage with authority data, disruption of internal service, and absence of linkage with other related organizations. To solve the limitations of the NAPS, we selected and analyzed advanced record management institutions that have built an ideal linkage service; checked the overall linkage structure of these institutions; and identified characteristics that could not be seen by other institutions. Also, elements that can be adopted from the NAPS were derived. Next, the current status of the NAPS linkage structure was analyzed to identify the parts that were not linked and the items that need to be improved in the linkage method, and specific advancement plans were suggested to solve these problems. The purpose of this study is to increase users' satisfaction with search and to advance the accessibility and utilization of records and internal services through improved linkage services of NAPS.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.4
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• pp.348-355
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• 2023

Biodiesel is known as an environmentally friendly neutral fuel, and a policy of obligatory mixing of a certain ratio is implemented on land. In this study, to verify the feasibility of using biodiesel as a ship fuel, component analysis, metal corrosion test, and storage stability test were performed on the mixing ratios of 0 %, 5 %, 10 %, and 20 % of marine diesel and biodiesel. Component analysis evaluated a total of eight factors including density, kinematic viscosity and flash point according to ISO 8217:2017 standards and the reliability of biodiesel through metal corrosion tests and storage stability tests under atmosphere temperature and harsh conditions (60 ℃) for 180 days. Results demonstrate that component analysis satisfied the ISO 8217:2017 standard in all biodiesel mixing ratios. Furthermore, as the biodiesel mixing ratio increased, the kinematic viscosity, density, and acid value increased and the sulfur content decreased. Metal corrosion rarely occurred in the case of carbon steel, iron, aluminum, and nickel, whereas in the case of copper, corrosion occurred under the influence of oxygen-rich biodiesel under the harsh conditions (60 ℃) of 20 % biodiesel mixture. As for storage stability, discoloration, sludge formation, and fuel separation were not visually confirmed.

• Journal of Korea Entertainment Industry Association
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• v.13 no.8
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• pp.647-659
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• 2019

The purpose of this study was to examine the relationship between the awareness of health care workers on the protection of patient health information and their practice of it in an attempt to provide some information on the policy setting of health care institutions about medical information protection. As a result, the awareness of the health care workers on the protection of patient health information and their practice of it were both the best in the communication area, followed by the patient health information management area and the area of direct contact with health information. As for the variables linked to their awareness and practice of patient health information protection, the type of the health care institutions, job satisfaction, religion and the departments in which they worked were significantly related. To determine what factors affected the patient health information management area, a multiple regression analysis was carried out by selecting the area of direct contact with patient health information and the communication area as independent variables and by selecting the patient health information management area as a dependent variable. And it's found that the patient health information management area became better when the area of direct contact with the information and the communication area were better.

• 한국노년학
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• v.39 no.2
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• pp.325-345
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• 2019

The purpose of this study is a exploratory study for understanding the process of the social isolation of the socially isolated elderly through the approach to their life history. The research was analyzed by one of the methods of qualitative research on life history, the conceptual framework of 'Dimensions, turning, and adaptation' of Mandelbaum(1973). According to the results of this study, the socially isolated elderly people were found to be socially isolated by experiencing complex difficulties such as family disconnection, poverty, poor job and health deterioration. Specifically, in the area of life, there was experience of poor relationship with parent, absence of family, poverty of family and unfavorable relationship with surrounding people in life with original family before isolation. They had bad jobs in the labor market, such as hard labor, delivery, business, and chores. In the area of turning point, we experienced family break due to the separation of the original family and the spouse due to various reasons such as financial crisis, parental divorce and death, spouse affair, economic difficulty. In a transitional stage in the life, many reasons such as the financial crisis, the death of parents, the extramarital affair and economic difficulties led to the disconnection from their original family and their spouses. In an adaptive phase, participants accepted the changed life at each turning point in their lives, carrying out their roles, compromising and trying to adapt properly. He said that their current life, which has entered the social safety net system of the people's basic recipients, has led him to live a more stable life and is adapting to personal hobbies and vicarious satisfaction through networks. This result is somewhat different from previous studies in which isolated elderly people were severely exposed to the risk of depression and loneliness. However, we should also consider the characteristics of this study that interviewed elderly people with relatively low isolation. Based on the results of this research, he presented various practical policy implications.

• 한국노년학
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• v.39 no.4
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• pp.941-958
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• 2019

The purpose of this study was to explore change trajectories patterns of Self-Rated Health in middle aged, to identify socioeconomic factors, self-esteem, family relationship factors, and to identify relevant predictors. For this purpose, the 2,418 middle aged, who married couples were extracted from the 2^nd to 12^st waves of Korea Welfare Panel Survey data. The data analysis included Latent Class Growth Analysis, multiple logistic regression. The change trajectories patterns of self-rated health in middle aged were classified into four types: (1) high state-retained type(46.3%), (2) low state-retained type(19.6%), (3) reduced type(17.5%), (4) increasing type(16.6%). Despite the control of chronic diseases that are closely related to health, when the low state-retained type, which is a crisis group, was set as the reference group for the self-rated health, the economic participation, self-esteem and satisfaction of the family relationship had a more inadequate effect than the high state-retained type. Likewise, when the reduced type, which is a crisis group, was set as the reference group for the self-rated health, the economic participation, self-esteem, satisfaction of the family relationship, and family stress had a more effect than the increasing type. Based on the analysis results, this study suggest political and practical intervention to maintain the proper health, and the details are as follows.

• Korean Journal of Social Welfare Studies
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• v.40 no.2
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• pp.227-252
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• 2009

This study set out to investigate implementation agency effect on participants' self-sufficiency in self-support program. Self-support program's implementation agency consist of civil groups and social welfare corporations. The final sample size was 602 program participants and 18 implementation agencies in Gwangju city, South Korea. Two-level hierarchical linear model was used for analysis. The major findings of this study are as follows. First, civil groups' participants were healthier, more often participated in business model, earned higher monthly income, participated shorter time rather than participants in social welfare corporation. Second, civil groups' participants showed low level of self-sufficiency than participants in social welfare corporations. These results means that self-support policy is not delivered uniformly because front-line implementation agencies develop work habits that influence the outcome of policy. And limitations and implications of this study were discussed with respect to further studies.

• KIPS Transactions on Computer and Communication Systems
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• v.12 no.10
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• pp.299-308
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• 2023

As the spectrum shortage problem has accelerated by the emergence of various services, New Radio-Unlicensed (NR-U) has appeared, allowing users who communicated in licensed bands to communicate in unlicensed bands. However, NR-U network users reduce the performance of Wi-Fi network users who communicate in the same unlicensed band. In this paper, we aim to simultaneously maximize the fairness and throughput of the unlicensed band, where the NR-U network users and the WiFi network users coexist. First, we propose an optimal power allocation scheme based on Monte Carlo Policy Gradient of reinforcement learning to maximize the sum of rates of NR-U networks utilizing rate-splitting multiple access in unlicensed bands. Then, we propose a channel occupancy time division algorithm based on sequential Raiffa bargaining solution of game theory that can simultaneously maximize system throughput and fairness for the coexistence of NR-U and WiFi networks in the same unlicensed band. Simulation results show that the rate splitting multiple access shows better performance than the conventional multiple access technology by comparing the sum-rate when the result value is finally converged under the same transmission power. In addition, we compare the data transfer amount and fairness of NR-U network users, WiFi network users, and total system, and prove that the channel occupancy time division algorithm based on sequential Raiffa bargaining solution of this paper satisfies throughput and fairness at the same time than other algorithms.

• Journal of the Korea Society for Simulation
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• v.32 no.4
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• pp.69-76
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• 2023

To improve the financial stability of the National Pension, an appropriate target rate of return should be established based on pension liabilities, and asset allocation policies should be formulated accordingly. The purpose of this study is to calculate the target rate of return considering the contributions of subscribers and the pension benefits, and based on this, derive an asset allocation. To do this, we utilized the internal rate of return methodology to calculate the target rate of return for each cohort. And then, we employed a Monte Carlo simulation-based re-sampling mean-variance model to derive asset allocation for each cohort that satisfy the target rate of return while minimizing risks. Our result shows that the target rate of return for each cohort ranged from 6.4% to 6.85%, and it decreased as the generations advanced due to a decrease in the income replacement rate of the National Pension. Consequently, the allocation of risky assets, such as stocks, was relatively reduced in the portfolios of future generations. This study holds significance in that it departs from the macroeconomic-based asset allocation methodology and proposes investments from an asset-liability management perspective, which considers the characteristics of subscribers' liabilities.