• Journal of the Korean Geotechnical Society
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• v.15 no.3
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• pp.161-176
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• 1999

A powerful numerical method that can be used for modeling rock-structure interaction is the Discontinuous Deformation Analysis (D D A) method developed by Shi in 1988. In this method, rock masses are treated as systems of finite and deformable blocks. Large rock mass deformations and block movements are allowed. Although various extensions of the D D A method have been proposed in the literature, the method is not capable of modeling water-block interaction, sequential loading or unloading and rock reinforcement; three features that are needed when modeling surface or underground excavation in fractured rock. This paper presents three new extensions to the D D A method. The extensions consist of hydro-mechanical coupling between rock blocks and steady water flow in fractures, sequential loading or unloading, and rock reinforcement by rockbolts, shotcrete or concrete lining. Examples of application of the D D A method with the new extensions are presented. Simulations of the underground excavation of the \ulcornerUnju Tunnel\ulcorner in Korea were carried out to evaluate the influence of fracture flow, excavation sequence and reinforcement on the tunnel stability. The results of the present study indicate that fracture flow and improper selection of excavation sequence could have a destabilizing effect on the tunnel stability. On the other hand, reinforcement by rockbolts and shotcrete can stabilize the tunnel. It is found that, in general, the D D A program with the three new extensions can now be used as a practical tool in the design of underground structures. In particular, phases of construction (excavation, reinforcement) can now be simulated more realistically.

• Journal of the Korean Geotechnical Society
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• v.34 no.1
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• pp.37-46
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• 2018

Hollow prestressed concrete filled steel tube (HCFT) piles, which compose hollow PHC piles inside thin wall steel tubes, are developed. In order to investigate the strength characteristics of HCFT piles, flexural and shear tests were conducted on HCFT piles as well as PHC and steel pipe piles with the same diameter. Results of the test program showed that the flexural strength of HCFT piles was 2.88 and 1.19 times those of ICP and steel pipe piles with thickness of 12 mm, respectively, and its shear strength was 2.40 times that of steel pipe piles. The shear key attached to the inside of thin wall steel tube did not affect the flexural behavior of HCFT piles. It was also observed that the flexural strengths of HCFT piles with diameters of 450 and 500 mm were 35 to 63% higher than the sum of the flexural strengths of its components, respectively, because the strength of concrete in compressive zone increased by confining effect of thin wall steel tube on concrete. HCFT piles used as upper piles in hybrid composite piles might decrease the lateral displacement and increase the structural safety of structures subjected to lateral loads.

• Journal of the Korean Geotechnical Society
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• v.34 no.1
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• pp.47-57
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• 2018

In recent years, vertical extension remodeling of apartment building is considered as one of the efficient ways to broaden and enhance the utilization of existing buildings due to the rapid development of population and decrement of land resources. The reinforcement of foundation is of great importance to bearing the additional load caused by the added floors. However, because of the additional load, the carried load by the existing piles would be in excess of its allowable bearing capacity. In this study, a conceptual construction method called preloading method was presented. The preloading method applies force onto the reinforcing pile before vertical extension construction. The purpose of preloading is to transfer partial load applied on the existing piles to reinforcing piles in order to keep each pile not exceeding the allowable capacity and to mobilize resistance of reinforcing pile by developing relative settlement. The feasibility and effect of preloading method was investigated by using finite numerical method. Two simulation models, foundation reinforcement with preloading and without preloading, were developed through PLAXIS 3D program. Numerical results showed that the presented preloading method is capable of sharing partial carried load of existing pile and develops the mobilization of reinforcing pile's frictional resistance.

• Journal of Information Technology and Architecture
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• v.10 no.3
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• pp.335-346
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• 2013

With the overwhelming development of information technologies, the need for software development that can deal with diversified and complex business processes has increased dramatically. As a result, companies prefer softwares that can handle far more complex processing ability and also it should be stable as well as easier to maintain. These ambivalent requirements keep the software development organizations from assessing the quantitative abilities, so that under the support of the U.S. Department of Defense the Capability Maturity Model (CMM) and Capability Maturity Model Integration (CMMI) have been developed. The CMMI upper levels for the software development companies will be evaluated to be excellent and authenticated, which drives the companies to get and maintain high levels of maturity. In this paper, a case study for a domestic software company has been exploited how to achieve CMMI level 4 and what kind of factors have been played an effective role. These issues at the domestic and international software and maintenance program, can influence the trustworthiness and marketing effects for the global market. In this paper, the company's actual case study will give clues to find out the important factors for the development and maintenance of software companies maturity levels.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.10a
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• pp.184-187
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• 2013

The Four Major Rivers Restoration Project of is the multi-purpose green growth project in South Korea. Some of the project was progressed by K-water and was declared complete on October 21, 2011. The Four Rivers Restoration Project of Korea was designed to be a packaged project that aims to resolve water-related problems such as floods and droughts and revitalize Korean public spaces near the water. K-water have applied the latest ICT(Information and Communication Technology) for the operating management of 4 Rivers Project facilities. We also have applied ICT for integrating drinking water production facilities. Applying these ICT, we have many experience for integrated water resources management, so we proposed. The first is that the big data collected should be analyzed for making decisions and taking actions while considering multiple viewpoints of how water should be managed. The second is that the new MMI(Man Machine Interface) program should be developed to use domestic needs and promote ease of maintenance for the integrated operation. The third is that the standardization of communication protocol is needed for seamless communication between equipments.

• Journal of the Korean Institute of Gas
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• v.18 no.4
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• pp.86-94
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• 2014

To develop a Root Cause Analysis Map which determines the cause of the accident in chemical laboratory, The Root Cause Analysis(RCA) Map for the laboratory areas was sketched from Phase 1 of the accident element to Phase 3 of the accident element, based on the RCA Map which is applied in the petrochemical industry. On the basis of laboratory RCA Map which was classified by using such method. The root causes of the 211 accident cases in laboratories were classified from Phase 4 to Phase 5 by the Cause Factor Charting technique and The cause of the accident data were inputted to EXCEL program. After that, The causes of the accident data were sorted and classified by type and each step. So 'Approximate Primary RCA Map Draft' was written. In addition, it was reaffirmed whether the root causes of 211 accidents of laboratory were appropriate to 'Primary RCA Map Draft'. By complementing the cause which was expected to cause future accidents, the RCA Map for chemical laboratories was developed. Based on 'RCA Map' proposed in this study, the causes of accidents were analysed management systems 35%, monitoring 12.2%, Human Factor Eng. 15.1% and education training 12.1% by the size of the frequency from Phase 1 to Phase 5.

• Resources Recycling
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• v.26 no.3
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• pp.79-91
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• 2017

The core of Hydrogen Fuel Cell Vehicles (FCV) is polymer solid fuel cell (PEFC), and the core material that generates electrochemical electricity in the cell is platinum catalyst. Platinum is localized in South Africa and Russia, and the world production of Pt is about 178 tons per year, which is expensive and recycled. At present, the amount of Pt used in PEFC is $0.2{\sim}0.1mg/cm^2$. In order to reduce the price of the battery and increase the FCV supply, the target is to reduce the amount of Pt used to $0.05{\sim}0.03mg/cm^2$. $Pt-Pd/Al_2O_3$, Pt/C, Pt/GCB, Pt/Au/C, PtCo/C, PtPd/C, etc. by using polyol method using nano Pt, improved Cu-UPD/Pt substitution method and nano-capsule method, Have been researched and developed, and there have been reported techniques for improving the activity of Pt catalysts and stabilizing them. This paper investigates the production technology of nano-Pt and nano-Pt catalysts, recycling of spent Pt catalysts and application trends of Pt catalysts.

• KDI Journal of Economic Policy
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• v.30 no.2
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• pp.61-97
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• 2008

This paper aims at analyzing the practice of job rotation in the Korean government and putting forward policy suggestions. The Korean government is often accused of low capacity and weak competitiveness, which mainly result from the low expertise of public officials. Considering the high quality of human resources flowing into the public sector in Korea, solutions should be found from the structure of the system. This paper regards frequent position changes due to excessive job rotation as a key factor undermining the accumulation of expertise and conducts in-depth analyses. The current practice of frequent rotation shows that the average tenure period of government officials at director level and above is only about one year, far shorter than those in major developed countries, which causes many problems such as low efficiency, lack of accountability and policy consistency, and low opportunity for accumulating expertise. Simple models are set up to analyze job rotation and other alternative personnel management systems. Analyses find that it would be desirable to have each individual experience various positions during the initial rotation period to find his/her own aptitude, and then accumulate expertise by settling in at a certain specialized field for a prolonged period of time based on the revealed aptitude in mid and high positions. This turns out to be in line with the structure of the Career Development Program which is being introduced. The model-based analysis of this paper distinguishes this study from preceding ones conducted in the traditional framework of personnel management study. Practical measures to mitigate the problems of frequent job rotation include rotating within the area of specialty, narrowing the scope of transfer, and reinforcing the minimum tenure period. However, since the current frequent rotation is fundamentally attributable to the rank system based on seniority, the present civil service classification system needs to be converted into a position classification system in the long run.

• Journal of dental hygiene science
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• v.4 no.2
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• pp.49-53
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• 2004

The purpose of this study is to show dental hygienist's stable and comfortable attire during dental paitients treatment, and to enhance dental hygienist's image. 486 adult patients who visited local dental clinics or centers in three cities of Jeonbuk province, Jeonju, Iksan and Gunsan were surveyed by self developed questionnaire. The collected data were analyzed with frequency, percentage and chi-square test (${\chi}^2$-test), using SPSS program. The results of this study are as follows: 1. Respondents preferred two-piece skirt (39.1%), the face with whole make-up (45.9%). There were significant differences in gender (p<0.01). 2. 36.2% of respondents preferred pink-colored uniforms. 3. Respondents preferred sandal (44.2%), there were significant differences in age, gender (p<0.01, p<0.05). 4. In terms of indication or identification for dental hygienists, 60.7% of respondents preferred nameplate. There were significant differences in age (p<0.05). 5. 75.9% of respondents thought that favorite uniform and costumes that patients prefer could help them feel easy.

• Journal of dental hygiene science
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• v.10 no.4
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• pp.279-286
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• 2010

To investigate the correlation between the perceived symptom of musculoskeletal diseases and psychosocial factors in dental professionals in Chungcheong province, a self-administered survey was conducted on 206 dental professionals in Chungcheong province from March 9th, 2009 to March 28th, 2009. SPSS WIN 12.0 software was used to analyze the data and the following results were obtained. 1. As for the perceived symptom degree of musculoskeletal diseases based on measured body parts, the frequency of 'high' was the highest in all the parts of the body. 2. As for gender, females showed higher interest in musculoskeletal diseases than males (p=.000). As for age, subjects ranged 26~30 years showed the highest interest in musculoskeletal diseases, which was statistically significant (p=.000). 3. Work satisfaction showed a positive correlation with the perceived symptom of musculoskeletal diseases in lumbar group and lower extremity group. Work stress showed a weak negative correlation with the perceived symptom of musculoskeletal diseases in lumbar group and lower extremity group. Coworker satisfaction showed a positive correlations with the perceived symptom in upper extremity group and lower extremity group. Hospital satisfaction showed a positive correlations with the perceived symptom in upper extremity group, lumbar group and lower extremity group. Working environment satisfaction showed a positive correlations with the perceived symptom in neck group, shoulder group, upper extremity group and lower extremity group. This study showed a correlation between psychosocial factors and the perceived symptom of musculoskeletal diseases based on body parts. Therefore, psychosocial factors should be considered when the prevention and management program of musculoskeletal diseases are developed.