• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.808-811
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• 2007

본 연구는 3톤/일급 이하 가스화 용융로에서 $1,400{\sim}1,500^{\cdot}C$, $7.5{\sim}8.0$ kg/$cm^2$의 안정적인 운전조건일 때, 시료로 Kideco 탄을 사용하고 이때 발생한 슬랙의 특성 및 슬랙의 재활용을 위한 벽돌제조 특성을 고찰하였다. 발생된 슬랙은 $Fe_2SiO_4$와 $SiO_2$가 결정상태로 일부 존재하거나, 중금속들이 결합되어 엉킨 구조인 비결정상태의 치밀한 형태로 이루어져 있었으며, 잔존탄소 함량이 0.06%로 미량 존재하였다. 또한 슬랙에는 중금속 농도가 Kideco탄보다 고농도로 존재하지만, 용출되는 중금속의 농도는 매우 낮아 환경적으로 안정한 물질로서 재활용이 가능한 특성을 지니고 있다. 슬랙 첨가 점토벽돌의 적합성을 평가하기위해 슬랙을 0%, 10%, 30% 첨가하여 벽돌을 제조하고 KS 산업규격에 따라 시험을 실시하였다. 분석결과 슬랙을 첨가할수록 제조한 벽돌의 흡수율이 낮아져 기존 제품에 비하여 우수한 것으로 측정되었다. 또한 압축강도와 휨강도는 기존 제품의 $80{\sim}86%$ 정도인 것으로 측정되었지만 KS 산업규격의 기준치보다 높은 수치를 나타내였고, 내산성, 내알칼리성, 열충격강도 또한 양호한 것으로 나타나, 슬랙을 이용하여 벽돌로 재활용하여 충분히 사용 가능한 것으로 확인되었다.

• Resources Recycling
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• v.9 no.1
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• pp.52-62
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• 2000

In order to maximize the recycling of converter slag to the more valuable fields, such as high quality aggregates for construction, cement industry and flux for ion making. It will be very important to control the compositions and properties of converter slag to suit the purpose of utilizastion. In this study, converter slag (STELCO, CANADA) was mixed with 5%~30% $SiO_2$and 7% carbon, and then reduced at $1650^{\circ}C$. After the reduction was completed, the reformed slags were cooled to room temperature in the furnace. All of the slags were then characterized using SEM-EDX, XRD and chemical analysis. Also the compressive strengths and densities of the reformed slags were measured to compare with natural aggregates. XRD analysis shows that th phases of reformed slags are changed from bredigite+merwinite mixed phases of 10% $SiO_2$added reduction to akermanite phases of 20% and 30% $SiO_2$ added reduction. But the SEM-EDX analysis revealed that the phase distribution of the reformed slags was changed very sensitively and complicately depends on the change of slag compositions. And also the properties of reformed slags are changed very much depend on the phase distribution. About one third of Cadmium and on fifth of Vanadium are remained in reduction reformed converter slag. Another heavy metal elements such as cobalt, zinc, lead are removed up to more than 90-95% of original slag. The compressive strength and density of 25% $SiO_2$ added and reformed slag is very near to natural granite. This is superior more than 10% to Thyssen's $SiO_2$ added and oxidized converter slag aggregates.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.74.2-74.2
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• 2011

석탄가스화 기술은 고온, 고압 조건에서 석탄과 산소의 불완전연소 및 가스화 반응을 통해 일산화탄소(CO)와 수소($H_2$)가 주성분인 합성가스를 제조하여 이용하는 현실적인 에너지원의 확보를 위한 방법인 동시에 이산화탄소를 저감할 수 있는 기술이다. 석탄가스화기 공급되는 석탄은 산소와의 부분 산화, 수증기 및 $CO_2$와의 반응에 의하여 합성가스로 전환되는데, 일반적으로 슬래깅 방식 석탄가스화기의 정상운전 중에 가스화기 내부 온도는 $1,400{\sim}1,600^{\circ}C$ 정도의 고온이며, 운전압력은 20~60 기압으로 매우 고압 상태에서 운전이 이루어지는데, 공급되는 석탄 시료의 성분들 중 가연성 물질의 99% 이상이 합성가스로 전환되는 반면, 회분에 해당되는 무기물의 대부분은 용융 슬랙 형태로 가스화기의 벽을 타고 흘러내리다가 슬랙탭을 통해 하부의 냉각조로 떨어지면서 급냉이 이루어지게 된다. 그러므로, 석탄가스화기 정상운전중 슬랙탭 주변의 온도를 고온으로 유지함으로써 용융슬랙의 고형화를 방지하는 것은 석탄가스화기의 안정적인 연속운전을 위하여 중요한 기술 중의 하나라고 할 수 있다. 따라서, 본 연구에서는 저급탄 가스화를 위한 1 톤/일급 고온, 고압 습식 석탄가스화기의 정상운전중 슬랙탭 부근에서 용융슬랙의 고형화를 방지하기 위한 슬랙탭 버너시스템의 설계를 진행하였으며, 안정적인 운전조건 도출을 위하여 보조연료(CNG)와 산소의 공급비율에 따른 화염특성 시험을 진행하였다.

• Journal of Energy Engineering
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• v.13 no.1
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• pp.82-91
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• 2004

In order to utilize inorganic components in coal and wastewater sludge as an environmentally stable material, slag-forming is considered as one of the suitable methods better than producing as an ash. Coal slag that was produced by gasification as well as the slag made from wastewater sludge by incineration or melting process have been analyzed with the viewpoint of recyclability. Slags produced by water quenching exhibited a cracked shape that has a size of few millimeters with sharp edges. Slags contain the unburned carbon content below 0.15％ and expose mostly amorphous structural characteristics. Analysis results in the extraction of heavy metal compounds demonstrate that both slags from coal and wastewater sludge could be utilized as a safe recycle material even with a Japanese environmental regulation that is ten times more stringent than the current Korean standard. Slags from coal and wastewater sludge show significant differences in contents of each heavy metal compound. Since the future trend of environmental regulation shifts to the control of total content for each heavy metal compound, proper mixing of slags that contain different heavy metal contents might be an option for manufacturing recycle materials.

• Resources Recycling
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• v.8 no.1
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• pp.44-51
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• 1999

Converter slag was reduced and modified by the simultaneous addition of carbon and waste foundry sand as a $SiO_2$ source. The basic properties such as phase distribution, composition, specific density, hardness. absorption of water and compressive strength of modified slags were measured. The Iron recovery was significantly affected by the basicity of slag. The properties of slow cooled-modified slags of basicity 1.34 arc very similar to the natural aggregates.

• Journal of the Korea Convergence Society
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• v.8 no.11
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• pp.343-352
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• 2017

In this study, the empirical analysis was conducted if the authentic leadership, which recently became an issue as an alternative of leadership, plays the moderating role in the relation between the participative budgeting and the budgetary slack. The hypotheses was established based on the literature review and the results of preceding studies in accordance with the scientific research procedure and the questionnaires were collected from the commissioned officers in charge of financial businesses in the military organization. Out of 200 questionnaires collected, 180 questionnaires were used for final empirical analysis excluding incomplete questionnaires. The summary of the research results shown through the regression analysis is as follows. First, the participative budgeting has positive(+) effect on the budgetary slack. Second, The authentic leadership plays the moderating role in the relation between the participative budgeting and the budgetary slack.

• The Transactions of the Korea Information Processing Society
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• v.7 no.7
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• pp.2229-2237
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• 2000

This paper intends to improve the problems of the slack stealing algorithm scheduling for periodic tasks with fixed priority and aperiodic tasks which occur dynamically. The Slack stealing algorithm reduces unnecessary waiting time by making the service possible immediately when the slack stealing server gives suitable priority to aperiodic tasks according to the status of aperiodic tasks arrivals at runtime. But no performs the slack stealing, we must calculate execution time of periodic tasks till the point of random. And, execution time of periodic tasks is being repeatedly every hours while the slack algorithm is applied. We show time complexity hen is used as to O(n) if the nubmer of tasks which is applied to the calculation is n. In this appear, due to stored in tables slack times and the execution times of the scheduled periodic tasks, the complexity of aperiodic tasks which is occurring dynamically reduced to O(log n) and improves the responses times. We prove the algorithm proposed in this paper through the simulation.

• Journal of Navigation and Port Research
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• v.38 no.2
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• pp.163-170
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• 2014

Domestic offshore business is oriented toward building drill-ships, FPSOs(Floating Production Storage and Off loading). But the equipments needed for offshore platforms are not so developed in Korea because the equipments can not be verified in Korean territory where the offshore platforms are not stationed. This study aims at finding some methods on entering into OSI for the maintenance and disassembly of fixed offshore platforms. Slack model is adopted to find out how slack assets could play a role in penetrating foreign markets. Firstly, entry into the South East Asian market is recommended. Secondly, forming a consortium is suggested by which taking part in offshore market can be easier. Finally, strategic plans for obtaining the technology for ship building equipments are needed as well as government support.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.2
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• pp.405-412
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• 2018

The budget is an essential tool for the systematic management of the organizational performance and for diagnosing the status of an organization. Effective budget execution is important to hospital management due to the nonprofit nature of hospitals. On the other hand, there are few studies regarding the budgetary slack of hospitals in Korea. The purpose of this study was to investigate the effects of the university hospital budgeting system characteristics on the budgetary slack. For this purpose, the data from 118 staff of a university hospital located in Seoul were collected by self-administered surveys. Frequency analysis, correlation analysis, and multiple regression analysis were carried out using Stata Ver. 14. The main results of this study were as follows. First, information asymmetry has a positive influence on the budgetary slack. Second, budget feedback and budget motivation have a negative effect on the budgetary slack. These findings suggest that the sharing of budget-related information among hospital staff is important for efficient hospital management. In addition, it is necessary to establish ways to enhance the feedback and motivation in budgetary activities for managing the budgetary slack systematically. The major strength of this study is that it draws attention to research concerning the budgetary slack of hospitals in the absence of research on the budgetary slack. The significance of this study was to provide an empirical basis for improving the efficiency of hospital management.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.43 no.2 s.308
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• pp.12-20
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• 2006

In scheduling of real-time tasks, the required hardware performance for a given set of tasks is determined based on the worst case execution time. For soft real-time tasks as multimedia applications, a lower performance hardware can service the tasks. Since the execution time of a task can vary in time, we can reclaim the slacks of early completed tasks for those of longer than average execution times. Then, the average ratio of deadline-miss can be lowered. This paper presents an algorithm, Aggressive Slack Reclamation (ASR), that tasks share slacks aggressively. A simulation result shows that ASR enhances the deadline-miss ratio and number of context switches than previous results.