• Computers and Concrete
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• v.13 no.6
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• pp.709-737
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• 2014

Fibre-reinforced self-compacting concrete (FRSCC) is a high-performance building material that combines positive aspects of fresh properties of self-compacting concrete (SCC) with improved characteristics of hardened concrete as a result of fibre addition. To produce SCC, either the constituent materials or the corresponding mix proportions may notably differ from the conventional concrete (CC). These modifications besides enhance the concrete fresh properties affect the hardened properties of the concrete. Therefore, it is vital to investigate whether all the assumed hypotheses about CC are also valid for SCC structures. In the present paper, the experimental results of short-term flexural load tests on eight reinforced SCC and FRSCC specimens slabs are presented. For this purpose, four SCC mixes - two plain SCC, two steel, two polypropylene, and two hybrid FRSCC slab specimens - are considered in the test program. The tests are conducted to study the development of SCC and FRSCC flexural cracking under increasing short-term loads from first cracking through to flexural failure. The achieved experimental results give the SCC and FRSCC slabs bond shear stresses for short-term crack width calculation. Therefore, the adopted bond shear stress for each mix slab is presented in this study. Crack width, crack patterns, deflections at mid-span, steel strains and concrete surface strains at the steel levels were recorded at each load increment in the post-cracking range.

• Journal of the Korea Concrete Institute
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• v.27 no.5
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• pp.471-480
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• 2015

The building structure is planned to maximize the use of space in recent. It was developed of a hybrid OCB (Optimized Composite Beam) for trying to take advantage of the maximize space. The OCB is composed of the steel h-beam section reinforced by open strands in negative moment zone and the psc concrete section in positive zone. Flexural behaviors of typical architectural bybrid OCB section was investigated. The 15 m OCB specimen was tested under three point static loading system. Following results are obtained from the tests; 1) The OCB with 15 m span develop initial flexural crackings under the 171% of full service loading. 2) Overall deflections of OCB under the service loads are less than those of the allowable limit in KCI Code provision. 3) The crack patterns, failure mode and ultimate load capacity of test specimen and F.E. model in this paper and they are compared to each other. The OCB is verified of structural reliability from the experimental results.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.9
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• pp.1734-1740
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• 2015

This paper introduces a generalized notion, referred to as joint locality, of the usual locality in distributed storage systems and proposes a code construction of binary locally repairable codes with joint locality ($r_1$=2, $r_2$=3 or 4). Joint locality is a set of numbers of nodes for repairing various failure patterns of nodes. The proposed scheme simplifies the code design problem utilizing complete multipartite graphs. Moreover, our construction can generate binary locally repairable codes achieving (2,t)-availability for any positive integer t. It means that each node can be repaired by t disjoint repair sets of cardinality 2. This property is useful for distributed storage systems since it permits parallel access to hot data.

• The Journal of Information Technology
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• v.5 no.3
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• pp.81-96
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• 2002

Recently business reengineering is the most attractive management reforming skill. Many of the Korean firms are paying attention to business reengineering and many of them have initiated it. The major purposes of this study are; (1) to investigate the relationship between each variable and success or failure of business reengineering, and (2) to examine interaction effects of measurement and performation variables. Two hundred eighteen questionaires were used for analysis. In order to throughout studies that I executed earlier. To look for dependence of critical success factors on analysis was performed to examine patterns between measurement and performance variables. In conclusion, the hypothesized relationships in the research model are supported by the empirical findings of this study. Additionally it is possible to establish theoretical reference system on the basis of critical success factors.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.1
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• pp.30-39
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• 2017

This paper concerns flexural strength of reinforced concrete beams containing recycled coarse aggregate (RCA) with compressive strength ranging from 31 to 38 MPa. The experimental parameters were replacement ratio of RCA and rebar ratio. Replacement ratio of RCA was 0, 30, 50 and 100%, and rebar ratio was 0.50, 0.79 and 1.14%. The RCA concrete beams were tested by using four-point bending test, and experimental results were discussed regarding crack and failure patterns, load-deflection relationship. Crack pattern of concrete beams with RCA was similar to that of concrete beams with natural coarse aggregate (NCA) but overall crack spacing of concrete beams with RCA was smaller than that of concrete beams with NCA. The crack width of RCA and NCA concrete beams was similar to each other. In addition, the test results of flexural strength were compared to the design code predictions. The design code predictions for flexural strength underestimated the experimental results. Therefore, the design code predictions for flexural strength of RCA concrete beams would offer conservative design.

• Journal of the Korean Society of Hazard Mitigation
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• v.7 no.5
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• pp.1-10
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• 2007

A laboratory investigation is conducted to characterize and quantify fatigue lives of continuously reinforced concrete pavements (CRCP) with initial design parameters. Eight specimens scaled were made based on results of finite-element analyses and stress-strain curve comparisons. Static tests were firstly performed to obtain magnitudes of static failure loads and to predict crack patterns before fatigue tests. The fatigue lives measured in the study were compared based on each initial design parameter. The comparison indicates that the fatigue lives of CRCP specimens with initial cracks increases with increasing the initial crack spacing, and CRCP specimens with reinforcements at top of the concrete slab have more fatigue lives than those with reinforcements at midheight of the concrete slab. In addition, the fatigue lives were significantly affected by soil conditions under the CRCP specimens. The results obtained in the study can be used for maintenance and retrofit of the continuously reinforced concrete pavements.

• Journal of the Korean Data and Information Science Society
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• v.26 no.6
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• pp.1271-1281
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• 2015

Competing risk analysis is widely applied to analyze a failure time with more than two causes. This paper discusses the application of a competing risk model to a economic activity state of workers with occupational injuries. In particular, main interest is to estimate the distribution of restarting time two kinds of economic activities, (i) returning to original working place and (ii) finding a new job. In this paper, we applied a cumulative incidence function to evaluate their patterns under several individual factors and working place's factor. Furthermore, a subdistributional regression model is applied to estimate the effect of these factors on the returning time. According to result, worker with higher education, younger age and longer working period had a higher chance to return an original working place while one with more severe injuries and skilled laborer had longer returning time to an original working place.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.5C
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• pp.423-431
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• 2010

In this paper, a modified sum-product algorithm to correct bit errors captured within the trapping sets, which are produced in decoding of low-density parity-check (LDPC) codes, is proposed. Unlike the original sum-product algorithm, the proposed decoding method consists of two stages. Whether the main cause of decoding failure is the trapping sets or not is determined at the first stage. And the bit errors within the trapping sets are corrected at the second stage. In the modified algorithm, the set of failed check nodes and the transition patterns of hard-decision bits are exploited to search variable nodes in the trapping sets. After inverting information of the variable nodes, the sum-product algorithm is carried out to correct the bit errors. As a result of simulation, the proposed algorithm shows continuously improved error performance with increase in the signal-to-noise ratio. It is, therefore, considered that the modified sum-product algorithm significantly reduces or possibly eliminates the error floor in LDPC codes.

• Journal of the Korean Society for Library and Information Science
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• v.32 no.1
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• pp.169-187
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• 1998

The primary purpose of this study is to compare printed index and abstract user's behaviours with digital index and abstract user's behaviours, and to verify of structured characteristics of a printed index and abstract. The major findings are as follows: (1) When the research topic is not specified enough, users tend to rely on printed indexes and abstracts search, whereas they utilize digital form in order to do retrospective search in the stage of research when the topic is determined. (2) Printed index and abstract users are expecting small number of literatures in search, whereas digital index and abstract users are expecting large number of literatures to be found The former are more satisfied with the result of search than the latter. (3) Digital index and abstract users experience more search failure than printed Index and abstract users. When they fail to find wanted materials, both users turn to the other form of indexes and abstracts. (4) Printed index and abstract users shows significantly less knowledge on online searching than digital index and abstract users.

• Korean Journal of Head & Neck Oncology
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• v.24 no.2
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• pp.169-173
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• 2008

Purpose：This is a retrospective study to evaluate the results of concurrent chemoradiotherapy in nasopharyngeal carcinoma. Material and Methods：From Mar 2000 to June 2005, 18 patients with nasopharyngeal carcinoma completed planned concurrent chemoradiotherapy. Stages were I in 1 patients, II in 2 patients, III in 7 patients and IV in 8 patients. Pathologic type was squamous cell carcinoma(WHO type 1) in 2 patients, non-keratinizing type(WHO type 2) in 8 patients and undifferetiated carcinoma(WHO type 3) in 8 patients. The follow up period ranged from 30 months to 95 months with a median of 56 months. Follow up was possible in all patients. Results：Response to concurrent chemoradiation therapy was a complete response in all patients. Patterns of failure were as follows：local recurrence in only one patient(5.6%) and distant metastases in three patients with N3 diseases(16.7%). The overall 5 year survival rates were 88.5%, the 5 year disease free survival rate was 77% and these were very good results. There were no significant differences in the local control and survival rates between the clinical stages and pathologic types. Conclusion：The outcome of the nasopharyngeal carcinoma treated with concurrent chemoradiotherapy was very good, even though most of the patients(15/18=83.3%) were in stage III and IV diseases. We concluded that concurrrent chemoradiotherapy in nasopharyngeal carcinoma showed the good local control and survival rates without significant complications. In the patients with N3 disease, we have to consider the more effective and strong chemotherapeutic regimens to prevent distant metastases.