• Journal of Korean Society for Quality Management
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• v.49 no.3
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• pp.255-268
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• 2021

Purpose: We sought to understand why a high-speed rotating projectile featuring a fuze-and-body assembly sometimes exhibited airburst, and we intended to improve the flight stability by eliminating airburst. Methods: We performed characteristic factor analysis, structural mechanics modeling, and dynamic modeling and simulation; and we scheduled firing tests to discover the cause of airburst. We used a step-by-step procedure to analyze the reliability function for selecting the bonding force standard that prevents airburst. Results: The 00MM high-speed rotating projectile features a fuze bonded to a body assembly; the bonding sometimes can break on firing. The resulting contact force, vibration and roll damping during flight generated yaw. Flight became unstable; fuze operation triggered an airburst. Our reliability test improved the bonding force standard (the force was increased). When the bonding force was at least the minimum required, a firing test revealed that airburst/flight instability disappeared. Conclusion: Analysis and identification of the causes of flight instability and airburst render military training safer and enhance combat power. Ammunition must perform as designed. Our method can be used to set standards that improve the performances of similar types of ammunition.

• Journal of Korea Society of Digital Industry and Information Management
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• v.15 no.1
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• pp.9-20
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• 2019

Korea's R&D investment has significantly increased in recent years. However, the efficiency of R&D investment is still in question. In order to examine the ways to improve the efficiency of R&D investment, this paper presents dynamic analysis on both quantitative and qualitative efficiency of R&D projects. A Data Envelopment Analysis(DEA)/Window method is used to analyze static and dynamic efficiencies of Industrial Material R&D projects in Korea from 2012 to 2016. As a result, statistically significant differences between quantitative and qualitative efficiency have been found. It has been observed that characteristics of Decision Making Units(DMUs) have an impact on both static and dynamic efficiencies. In particular, textile and ceramic projects showed relatively stable qualitative efficiency for a short-term perspective, while steel and chemical projects showed such stability for a long-term perspective. Among the types of project principals, universities showed relatively stable efficiency, compared with private sectors and research institutes. The results of this paper can be used as a guideline to manage the performance and stability of R&D projects' efficiency.

• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.2
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• pp.164-174
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• 2007

Phenomena of hydraulic transient such as water hammer should be analyzed to design the pipeline systems effectively in dam. Surge tanks generally are used to reduce change in pressure caused by hydraulic transient from load changes on the turbines. In this study, the appropriate scale of surge tank with chamber is investigated for dam safety management. The variation of water level in the surge tank are computed using governing equation. Using the Thoma-Jaeger's stability condition, static and dynamic stability are investigate for the cases of flood water level, normal high water level, rated water level and low water level. Finally appropriate diameters of shaft and chamber are determined in the surge tank with chamber.

• Journal of Korean Society of Forest Science
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• v.109 no.2
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• pp.202-210
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• 2020

This study investigated the optimal levels of stand density control considering the stability of Larix kaempferi stands. A stand density management diagram was developed from 259 sample plots. Based on these data, we determined an optimal level of the stand density control by identifying the relationship between the relative yield index (Ry) and height-to-diameter ratio. The estimated r-square (R²) of the stand density management diagram is 0.600. The analysis of the relationship between Ry and the slender tree incidence showed that when the stand density exceeded a certain threshold and the ratio of slender trees rapidly increased. The critical value of Ry was 0.63. The results of this study are expected to contribute to the establishment of stand management strategies that can reduce damage from natural causes, such as wind and snow, and to develop stand practice systems for the improved productivity of commercial forests.

• The Journal of the Korea Contents Association
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• v.13 no.12
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• pp.484-493
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• 2013

The Korean Government has provided public rental housing to stabilize civilian dwelling. However, unreliable management of public rental housing threatens the stability of residency. This study analyzes the default of public rental housing and the cause of default through a case study, which was intended for the residents in apartment complexes in danger of default. It also suggests countermeasures to cope with the problem of public rental housing. The results are listed as follows. First, rental housing apartments contribute a lot to the housing stability policy. On the other hand, the default of housing development, which is derived from the bankruptcy of housing management companies and the negligent control of government, brings about a serious problem for housing stability. Second, although the government has made a steady effort to solve this default problem, 9000 residents from 8 apartment complexes in Korea have experienced extreme unstable residency. Third, there are many causes for the default of public rental housing such as unqualified management companies and cursory monitoring by the government. The fundamental solution is to prevent public rental housing management companies from managing, or to build a new management system of public rental housing. To solve this problem, it's recommendable to delete the application term in the special law on the default of public rental housing so that it can be applied to all default apartments. If it is not possible to perform the policy for financial reasons, a new supply of civil housing provided by private companies needs to be re-examined completely or banned.

• Journal of the Korean GEO-environmental Society
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• v.15 no.10
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• pp.43-51
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• 2014

Recently, National Emergency Management Agency constructs integrated information system for preventing national earthquake based on underground information. In the past, there are numerous difficulties in construction and management of underground information, because underground information is constructed by each management agency. But a link and application of underground information are available because of government 3.0. This study shows the integrated information system for preventing national earthquake based on real-time link of underground information. The integrated information system for preventing national earthquake developed in this study consists of boring information input modules, underground information search/analysis modules based on V-world tile map, user authority management modules, user management modules and real-time liaison interface modules. Also, this study proposes enhancement plan to construct integrated information system for preventing national earthquake stably and strongly. Stability test conduct on stability of data storage, system stability and consistency of processing speed test results show stability of the integrated information system for preventing national earthquake is high.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1999.10c
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• pp.618-624
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• 1999

For many soft ground embankment projects , instrumentation programs for stability and settlement management is being essential . This usually leads to generate large volume of data, which can be used for further research. Database technique is most effective method for data management . Data produced by soft ground embankment instrumentation can not be used by itself but must be reproduced using geotechnical analysis technique. In this study, a intelligent database system for softground called IDSIM was developed to examine applicability intellgent database. . The IDSIM analysis instrumentation data automatically and present results by Web/DB interface successfully.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.10a
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• pp.44-51
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• 2002

The construction road and addition work are increasing now. Therefore, slope stability is important in construction slope on the fault and fractured zone. Rock bolt method, soil nailing method and anchor method are applied to reinforcement method of slope. This paper is the study for construction management on reinforcement method of slope.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.960-964
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• 2004

During system resource improvement process that based on Object-Oriented technology could be affect to the continuous system performance if lack appropriate management and control objects mechanism. This paper proposes a methodology to support continuous system performance and its stability. The adoption is based on Java Container Framework and Collections Framework for object collection. Also includes Software Engineering, Object Migration and Multiple Class Loaders mechanism accommodate to construct Continuous Migration Container (CMC). CMC is a runtime environment provides interfaces for management and control to support upgrading object process. Upgrade object methodology of CMC can be divided into two phase are object equivalence checking and object migration process. Object equivalence checking include object behavior verification and functional conformance verification before object migration process. In addition, CMC use Multiple Class Loaders mechanism to support reload effected classes instead of state transfer in migration process while upgrading object. These operations are crucial for system stability and enhancement efficiency.

• Journal of Korea Multimedia Society
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• v.18 no.11
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• pp.1375-1382
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• 2015

This paper aims to introduce the numerical methods for solving the optimal control theory to model bufferbloat problem. Mathematical tools are useful to provide insight for system engineers and users to understand better about what we are facing right now while experiment in a large-scale testbed can encourage us to implement in realistic scenario. In this paper, we introduce a survey of the numerical methods for solving the optimal control problem. We propose the dynamic optimization sweeping algorithm for optimal control of the active queue management. Simulation results in network simulator ns2 demonstrate that our proposed algorithm can obtain the stability faster than the others while still maintain a short queue length (≈10 packets) and low delay experience for arriving packets (0.4 seconds).