• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.5
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• pp.1342-1348
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• 1998

The major limitation of MOM solution has alaways been the computer CPU time and storage size, needed to carry out the impedance matrix computation. A new formulation technique using Sorce Superimposion method is presented in order to cut down computerstorage requirements and CPU time based on the equivalence principle and induction theorem. The numerical results are shown to give good agreement to those calculated by the conventional method and also application example is presented.

• Microbiology and Biotechnology Letters
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• v.19 no.2
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• pp.186-192
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• 1991

It is very important to have a good kinetic model which considers the effects of both ammonium and glucose for the control and optimization of the poly-${\beta}$-hydroxybutyrate (PHB) fermentation. A kinetic model for the growth of Alcaligenes eutrophus and the biosynthesis of PHB under both ammonium and glucose limitation was proposed. Growth rate of residual biomass was expressed as a function of concentrations of residual biomass, glucose and ammonium having glucose inhibition. PHB production rate was expressed as a function of concentrations of residual biomass, glucose, ammonium and PHB content having ammonium and product inhibitions. Novel approaches were made to estimate the parameters in the model equations which considered two limiting substrates. Model parameters were evaluated by graphical and simplex methods. The proposed kinetic model fitted the data very well.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10c
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• pp.217-222
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• 1998

In these days, mostof marine structures are constructed by reinforcement concrete due to economic reason. Theoretically, it is widely recognized that rebar in sound concrete is safe against corrosion because of the high alkalinity of concrete. However, corrosion for reinforcement concrete made by marine aggregate and exposed to ocean enviroments has become serious social problem. Especially in Korea, with the rapid economic growth construction activities have been accelerated and needed more natural aggregate. Therefore, inevitably marine aggregate had to be used due to limitation of good quality aggregate. In this study, as a part of efforts to establish the fundamental counterplan on corrosion problems related to marine aggregate, concrete specimens with chloride containing material and inhibitor have been studied. And, in order to analyze corrosion characteristics several electrochemical techniques including half-cell potential survery, linear and cyclic polarization tests were carried out.

• Research in Community and Public Health Nursing
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• v.20 no.4
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• pp.503-512
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• 2009

Purpose: This study was to investigate the factors influencing hotel workers' health practice. Methods: This study was based on the partial PRECEDE model. The subjects of this study were 261 servers sampled at random from a hotel located in Seoul. For the statistical analysis of collected data, descriptive statistics, t-test, ANOVA and logistic regression were performed with the SAS (Version. 8.01) program. Results: There were statistically significant primary factors influencing different parts of health practice. That is, regular exercise was influenced by gender, age and marital status, diet habit was by marital status, and type of working, prohibition of smoking was by gender, age and type of employment, and drinking by gender and job stress. Conclusion: This study has a limitation in generalized application to hotels in this country because it is a cross-sectional examination about the factors affecting health practice in the employees of a hotel. Further study is needed with various and broad variables that promote health practice and contributed to the development of health promotion programs.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.693-698
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• 2002

The production accounts of domestic by-product is increased after 1990's. It is worried about the life reduction of dump land, as dump land's capacity have reached to limitation and the amount of construction industrial wastes is going higher. Recently, recycling aggregates could be gained from the reconstruction works using recycle process. And the study and research of recycle concretes developed concrete application methods. It could put some outcome of studies to practical use for concrete products. The methods of crushing waste concrete are going diverse. In this study, the fundamental experiments and recycling application is investigated and analyzed with use of recycling aggregate which made of mechanical crush and underwater electrical impact crush. and the difference between underwater electrical impact crush, mechanical crush and natural aggregates is studied.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.849-854
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• 2002

From the analysis results of some as-built drawings in national roadway bridges in Korea, many bridge piers are expected to show complex shear-flexural behaviour under earthquakes. But the previous research works about the seismic evaluation of bridges considered flexural behaviour RC piers only. In addition, the past bridge design specifications in Korea didn't include limitation on the amount of longitudinal lap splices in the plastic hinge zone of piers. Thus a large majority of non-seismically designed bridge piers in Korea may have lap splices in plastic hinge zone. In this study, prototype pier was selected among existent bridge piers whose failure mode is expected to be complex shear-flexural mode. And then, full scale and 1/2 reduced scale model RC piers with various longitudinal lap splice details were constructed. From the quasi static test results on these model RC piers, the effect of longitudinal lap splices on the seismic performance of bridges piers was analyzed. And the seismic capacity of the non-seismically designed shear-flexural RC piers was evaluated.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.112-115
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• 2004

Bond between reinforcing bar and surrounding concrete is supposed to transfer load safely in the process of design of reinforced concrete structures. Bond failure of reinforcing bar generally take place by splitting of the concrete cover as bond force between concrete and reinforcing bars exceeds the confinement of the concrete cover and reinforcement. However, the confinement force has a limitation. Thus, the only variable is the bearing angle corresponding to the change of bond force. Higher rib height bars possessing higher shearing resistance can maintain higher bearing angle and higher splitting resistance when bars are highly confined, and consequently higher bond strength, than lower rib higher bars. In this study, from the evaluate bond strength of high Relative Rib Area Bars Using beam-end test specimens are compared with the current provisions for development of reinforcement, and the improved design method of bond strength is proposed.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.68-71
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• 2004

In the shear strengthening with FRP sheets, beams are wrapped around the webs and tension face of critical shear span by fiber sheets. The shear strength of RC beam strengthened with FRP sheets must be calculated based on the effective strain that can be developed in the FRP sheets at ultimate stage because the final failure modes of beams are governed by premature debonding of FRP sheet due to the limitation of bonded length by beam depth. An experimental study is carried out to evaluate the shear strengthening effect of AFRP or GFRP sheets with respect to shear reinforcement ratio of rebar. From the test results, it was found that the additional shear strength provided by GFRP or AFRP can be estimated by $p_w{\cdot}f_w$ based on the maximum effective strain of FRP sheet $4,000m{\mu}$ proposed by ACI 440 committee.

• Journal of Ocean Engineering and Technology
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• v.26 no.4
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• pp.1-7
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• 2012

This paper deals with the global path planning problem for AUVs (autonomous underwater vehicles) in a tidal current field. The previous researches in the field were unsuccessful at simultaneously addressing the two issues of obstacle avoidance and tidal current-based optimization. The use of a genetic algorithm is proposed in this paper to move past this limitation and solve both issues at once. Simulation results showed that the genetic algorithm could be applied to generate an optimal path in the field of a tidal current with multiple obstacles.

• Journal of Korean Foot and Ankle Society
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• v.24 no.2
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• pp.55-60
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• 2020

Among the various surgical treatment methods for osteochondral lesions of the talus, autologous osteochondral transplantation (AOT) is a useful procedure in cases of a large defect, subchondral cyst, and failed primary bone marrow stimulation procedure. Although bone marrow stimulation alone may not regenerate the damaged plate sufficiently, AOT has the advantage of being able to replace the subchondral bone plate and cartilage with a new one at a same time. Nevertheless, postoperative cyst formation or pain may persist and donor site morbidity is still a limitation of AOT.