• Tunnel and Underground Space
• /
• v.23 no.4
• /
• pp.288-296
• /
• 2013

In this study, a total of 13 mines were finally selected as study subjects and field measurements were conducted. Thereafter, calculations of thermodynamic natural ventilation were attempted using spread sheets and solutions for natural ventilation of mine types with multiple vertical shafts were obtained. Based on the results, natural ventilation of each mine was quantified. In addition, changes in natural ventilation energy (NVE) and natural ventilation pressure (NVP) were estimated assuming mine deepening and the resultant values were applied to mine conditions to observe changes in flow rates. Natural ventilation pressure in domestic mines is generally calculated to be in a range of 5 Pa~300 Pa. Although NVP increases as the depth increases, resistance also increases. Therefore, as the depth increases, flow rates show a tendency of converging on a certain value because of the relationship between NVP and mine resistance. Natural ventilation using shafts with depth differences is effective up to depths of 200~300 m. However, flow rate change rates resulting from NVP are small at depths deeper than approximately 200~300 m. Therefore, if a mine is deepened over 300 m, NVP will become insufficient and thus additional pressure obtained through mechanical ventilation will be necessary.

• Journal of Korean Society of Transportation
• /
• v.18 no.6
• /
• pp.89-99
• /
• 2000

To cope with the limits of conventional O-D trip matrix collecting methods, several approaches have been developed. One of them is bilevel Programming method Proposed by Yang(1995), which uses Sensitivity Analysis Based(SAB) algorithm to solve Generalized Least Square(GLS) problem. However, the SAB a1gorithm has revealed two critical short-comings. The first is that when there exists a significant difference between target O-D matrix and true O-D matrix, SAB algorithm may not produce correct solution. This stems from the heavy dependance on the historical O-D information, in special when gravel Patterns are dramatically changed. The second is the assumption of iterative linear approximation to original Problem. Because of the approximation, SAB algorithm has difficulty in converging to Perfect Stackelberg game condition. So as to avoid the Problems. we need a more robust and stable solution method. The main purpose of this Paper is to show the problem of the dependency of Previous models and to Propose an alternative solution method to handle it. The Problem of O-D matrix estimation is intrinsically nonlinear and nonconvex. thus it has multiple solutions. Therefore it is necessary to require a method for searching globa1 solution. In this paper, we develop a solution algorithm combined with genetic algorithm(GA) , which is widely used as probabilistic global searching method To compare the efficiency of the algorithm, SAB algorithm suggested by Yang et al. (1992,1995) is used. From the results of numerical example, the Proposed algorithm is superior to SAB algorithm irrespective of travel patterns.

• Journal of the Korean Wood Science and Technology
• /
• v.38 no.3
• /
• pp.191-198
• /
• 2010

This research was performed to investigate the effect of hydrogen peroxide on the stain removal in japanese hackberry. Response surface method (RSM) was used to optimize the bleaching conditions such as reaction temperature, reaction time and the concentration of hydrogen peroxide. Fifteen different bleaching conditions were selected according to $2^3$ factorial central composite design (CCD). The bleaching effect were evaluated by lightness differences of wood surface before and after the bleaching. The RSM model was determined and its $R^2$ values were 0.93, showing it well represented the bleaching effect. The most affecting factor on the stain removal was the concentration of hydrogen peroxide, followed by reaction time and reaction temperature. Second degree of concentration was proved to have an effect on the bleaching. Bleaching rates above 3% concentrations of hydrogen peroxide were tended to be slightly decreased, and low bleaching effect was found at $20^{\circ}C$. The determined RSM model may offer very practical ways to obtain the desired levels of bleaching because it offers multiple solutions.

• The Journal of the Acoustical Society of Korea
• /
• v.20 no.5
• /
• pp.69-75
• /
• 2001

In this paper, a fast and easy impedance matching method, which could give the impedance matching component for the general 1 or 2-port network was introduced. First, the entire network structure was defined which consists of the network part to be matched and the impedance matching part composed of inductors and capacitors. Next, the transmission matrix and input and output impedances of the entire network from the terminal impedance conditions were calculated, then the exact solutions for the matching components were obtained. To verify the efficiency of this method, this method was applied to the CDMA If band withdrawal weighted SAW transversal filter, and investigated the effects of the impedance matching before and after, through the simulation and experiment. As the result, the performance of a fractional bandwidth of 1.2%, insertion loss of 29 dB, and VSWR of 80 have improved to a factional bandwidth of 1.8％, insertion loss of 9 dB, VSWR of 3 at 85.38 MHz center frequency. The result shows that this impedance matching method could be used in the SAW devices and other types of 1 or 2-port network.

• The KIPS Transactions:PartA
• /
• v.17A no.6
• /
• pp.265-274
• /
• 2010

As the process technology scales down and integration densities continue to increase, interconnection has become one of the most important factors in performance of recent multi-core processors. Recently, to reduce the delay due to interconnection, 3D architecture has been adopted in designing multi-core processors. In 3D multi-core processors, multiple cores are stacked vertically and each core on different layers are connected by direct vertical TSVs(through-silicon vias). Compared to 2D multi-core architecture, 3D multi-core architecture reduces wire length significantly, leading to decreased interconnection delay and lower power consumption. Despite the benefits mentioned above, 3D design technique cannot be practical without proper solutions for hotspots due to high temperature. In this paper, we propose three floorplan schemes for reducing the peak temperature in 3D multi-core processors. According to our simulation results, the proposed floorplan schemes are expected to mitigate the thermal problems of 3D multi-core processors efficiently, resulting in improved reliability. Moreover, processor performance improves by reducing the performance degradation due to DTM techniques. Power consumption also can be reduced by decreased temperature and reduced execution time.

• Journal of the Korean Society for information Management
• /
• v.29 no.1
• /
• pp.303-329
• /
• 2012

This study measures the efficiency of public libraries, library services, and management to contribute to the proposed model for efficiency analysis, reflecting the characteristics in public libraries. This analysis model of applying the empirical research pursues the solutions to provide efficiency. Although many attempts have been made domestically and internationally to study the measurement of the efficiency, mere application of analysis techniques used in the other public sectors has led to the inadequate measurement for characteristics of library services. In addition, there has not been any attempt made to deduce a general theory for the study from the measurement results. In this study, an analysis model that reflects the inherent characteristics in library services is suggested to be analyzed empirically, and this leads to the understanding of efficiency factors. The results of the study show that the efficiency of current public libraries can be increased on the basis of input and output. Therefore the commitment to increase the level of output to meet the current need shall continue by the amount, rather than by the commitment to reduce the level of input. Finally, the factors influencing the efficiency are the number of users, the physical environment, professional staffs, events planning, and electronic resources. After analyzing the five factors via multiple regression analysis, three factors such as the number of users, professional staff and events planning proved causal relationship with the efficiency.

• Korean Security Journal
• /
• no.54
• /
• pp.127-148
• /
• 2018

As the role and the importance of private security are emphasized in an independent way, as well as in a supportive way for police affairs, this study aims to figure out factors affecting job satisfaction of private security guards by investigating their job satisfaction. This study also suggests some solutions for improvement of their job satisfaction, such as enhancing task motivation and professionalism of private security guards. For the research were used SPSS(Statistical Package for the Social Science) WIN 24 programs. Frequency analysis, correlation analysis, multiple regression analysis and Crosstabulation analysis were performed as analytic methods. As a result of the study, the most fundamental factor in the job satisfaction of the private security guards was 'social recognition'. Social recognition forms when private security guards are trusted as professionals and the value of a job is enhanced. The policy recommendations to improve the job satisfaction of private security guards can be explained as follows. First, a government certification system should be established in an attempt to recruit professional private security guards. Second, in order to improve the work ability of private security guards, it is necessary to designate a special educational institution for a private security guards and provide systematic education. Third, the wage of private security guards should be readjusted to a realistic level. Fourth, it is necessary to secure substantial effect on the permission and the supervision of private security business. Finally, the business area based on public interest should be expanded.

• Journal of KIISE:Computing Practices and Letters
• /
• v.10 no.2
• /
• pp.134-145
• /
• 2004

With rapid growth in the amount of data transferred on the Internet, traditional storage systems have reached the limits of their capacity and performance. SAN (Storage Area Network), which connects hosts to disk with the Fibre Channel switches, provides one of the powerful solutions to scale the data storage and servers. In this environment, the maintenance of data consistency among hosts is an important issue because multiple hosts share the files on disks attached to the SAN. To preserve data consistency, each host can execute the disk I/O whenever disk read and write operations are requested. However, frequent disk I/O requests cause the deterioration of the overall performance of a SAN cluster. In this paper, we introduce a SANtopia global buffer manager to improve the performance of a SAN cluster reducing the number of disk I/Os. We describe the design and algorithms of the SANtopia global buffer manager, which provides a buffer cache sharing mechanism among the hosts in the SAN cluster. Micro-benchmark results to measure the performance of block I/O operations show that the global buffer manager achieves speed-up by the factor of 1.8-12.8 compared with the existing method using disk I/O operations. Also, File system micro-benchmark results show that SANtopia file system with the global buffer manager improves performance by the factor of 1.06 in case of directories and 1.14 in case of files compared with the file system without a global buffer manager.

• KIPS Transactions on Computer and Communication Systems
• /
• v.9 no.8
• /
• pp.171-180
• /
• 2020

Smart Factory consists of digital automation solutions throughout the production process, including design, development, manufacturing and distribution, and it is an intelligent factory that installs IoT in its internal facilities and machines to collect process data in real time and analyze them so that it can control itself. The smart factory's equipment works in a physical combination of numerous hardware, rather than a virtual character being driven by a single object, such as a game. In other words, for a specific common goal, multiple devices must perform individual actions simultaneously. By taking advantage of the smart factory, which can collect process data in real time, if reinforcement learning is used instead of general machine learning, behavior control can be performed without the required training data. However, in the real world, it is impossible to learn more than tens of millions of iterations due to physical wear and time. Thus, this paper uses simulators to develop grid sortation systems focusing on transport facilities, one of the complex environments in smart factory field, and design cooperative multi-agent-based reinforcement learning to demonstrate efficient behavior control.

• Korea Journal of Hospital Management
• /
• v.18 no.4
• /
• pp.78-96
• /
• 2013

The purpose of this study is to analyze the emergency health care utilization using status according to income class. The target was the 2011 data out Korea Health Panel's raw data. 2011 data composed of total 17,035 people from total 5,741 households. This study set total 1,101 adults over full-20-years old having used an emergency health care utilization as its analysis target. In order to find out the number of emergency health care utilization use according to income class and the influential factors on emergency health care utilization cost, this study conducted the multiple regression analysis. And in order to more accurately analyze the emergency health care utilization use status depending on the income class and the features of emergency health care utilization use status, this study developed Models. As the result, this study found following findings. First, as the income class was lower, the gender was male, the age was lower, and the user has spouse, the user was not a business owner or a paid worker, the user is a house owner, the emergency medical facility type was a clinic, the means of transportation was others rather than 119 ambulance, the reason visiting emergency medical facility was belonged to others rather than accidents or poisoning, then the number of emergency was increased. Second, as the user was in higher income class, received the health insurance benefits, the using medical facility was general hospital, used 119 ambulance more often, stay days in emergency was shorter, then health care utilization cost was increased. In this study investigating the data out of Korea Health Panel, it was found that while the number of emergency health care utilization use was increased in the lower income class, but the emergency health care utilization cost was increased for higher income class. It is considered that this finding was caused from the facts that lower income class was more often exposed to dangers for physical health, so the number of emergency health care utilization use was increased, but their health care utilization cost was decreased because of their economic burdens against various examinations and their difficulties to pay such costs, comparing to that of higher income class. Therefore, in order to solve unequal problem of emergency health care utilization use between lower and higher income classs, it is required to set suitable solutions like the disease prevention effort by facilitating national health check-up programs, the enhancement of public health services in quantity and quality, the emergency health care utilization securing policy at using medical facilities, the promotional, educational activities about emergency health care utilization delivery system, the enhanced accessibility of emergency health care utilizations and emergency medical facilities.