• Journal of the Korean Institute of Gas
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• v.16 no.3
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• pp.29-34
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• 2012

Investigating safer ways to design and use to prevent a loss of life and property by failure of the structures are necessary and assessing total fatigue life with initiation and propagation of fatigue crack accurately through fatigue analysis is very important. The object of this study is to examine the initial life and propagation life when the fatigue crack is introduced from the root which is likely to appear in LOP(Lack of Penetration) cruciform fillet welded structure including bridges, ships and gas storage facilities which are impossible to be fully penetrated and to measure the rate of fatigue life until the final cleavage failure. As the result, each rate of fatigue life for fatigue failure is somewhat different in the range of 5% according to the thickness of material, however, the overall rate of initial life is in the range of 34~39% and propagation life showed the range of 61~66%.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.1
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• pp.117-124
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• 2010

Different to other social infrastructures, bridge elements or bridges can be damaged or collapsed and this may cause death toll and severe social and economical damage, bridges should be managed to maintain a safety level. Diverse strengthening methods is developed to improve a deteriorated bridge performance up to original design level. But rational decision-making process and methodologies to select a optimum strengthening method are absence yet in Korea. This paper therefore derived items and proposed methodologies for quantity estimate considering uncertainty to select a optimum strengthening method among conceptually designed alternatives. And also, to demonstrate the applicability and verification of the proposed approach, it was applied to select the optimum strengthening method for the deteriorated T-shape concrete girder bridge. The model and the procedure can greatly contribute to the uncertainty-oriented alternative selection.

• Journal of the Korean Electrochemical Society
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• v.22 no.2
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• pp.60-68
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• 2019

High-voltage operation of the lithium ion battery is one of the advantageous approaches to obtain high energy capacity without changing the conventional cell components and structure. However, operating at harsh condition inevitably results in severe side reactions at the electrode surface and structural disintegration of active material particles. Herein we coated layers composed of $Al_2O_3$ and ZnO on the electrode based on NCM using atomic layer deposition (ALD). Thicker layers of novel Al-doped ZnO (AZO) coating compared to conventional ALD coated layers are prepared. Cathode based on NCM with the varying AZO coating thickness are fabricated and used for coin cell assembly. Effect of ALD coating thickness on the charge-discharge cycle behavior obtained at high-voltage operation was investigated.

• The Journal of Engineering Geology
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• v.19 no.1
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• pp.63-70
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• 2009

The optical fiber cable acting as a sensor was embedded in the underground research tunnel and portal area in order to monitor their stability and the spatial temperature variation. This system includes two types of sensing function to monitor the distributed strain and temperature along the line, where sensor cable is installed, not a point sensing. According to the results of one year monitoring around the KURT, there is no significant displacement or movement at the tunnel wall and portal slope. However, it would be able to aware of some phenomena as an advance notice at the tunnel wall which indicates the fracturing in rockmass and shotcrete fragmentation before rock falls accidently as well as movement of earth slope. The measurement resolution for rock mass displacement is 1 mm per 1 m and it covers 30 km length with every 1m interval in minimum. In temperature, the cable measures the range of $-160{\sim}600^{\circ}C$ with $0.01^{\circ}C$ resolution according to the cable types. This means that it would be applicable to monitoring system for the safe operation of various kinds of facilities having static and/or dynamic characteristics, such as chemical plant, pipeline, rail, huge building, long and slim structures, bridge, subway and marine vessel. etc.

• Journal of Korean Tunnelling and Underground Space Association
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• v.5 no.3
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• pp.241-250
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• 2003

Rock mass is very inhomogeneous in nature and data obtained by site investigations and tests are very limited. For this reason, many uncertainties are to be included in the process of constructing structures in rock mass. In the design of a tunnel, support pattern, advance rate, and excavation method, which are important design parameters, must be determined to be optimal. However, it is not easy to determine those parameters. Moreover if those parameters are determined incorrectly, unexpected risk occurs such as decrease in the stability of a tunnel or economic loss due to the excessive supports etc. In this study, how to determine an optimal support pattern and advance rate, which are the important tunnel design parameters, is introduced based on a risk analysis. It can be confirmed quantitatively that the more supported a tunnel is, the larger reliability index becomes and the more stable the tunnel becomes. Also an optimal support pattern and advance rate can be determined quantitatively by performing a risk analysis considering construction cost and the cost of loss which can be occurred due to the collapse of a tunnel.

• The Journal of the Korea Contents Association
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• v.8 no.5
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• pp.224-236
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• 2008

To enhance the quality of disaster management service, the paradigm shift is necessary from the supplier-centered approach to demander-centered approach. In this paper, demander means all the policy actors that participate in the field of disaster such as central & local governments, emergency rescue systems, civil volunteer groups as well as the disaster victims. In this study, we analyze the current problems of disaster management service in demanders' point of view through in-depth interviews and then address suggestions based on each entity's recognitions and understandings related. The results are as follows: 1) Lack of systemicity in the current disaster management service. 2) The mutual distrust and understanding among the policy actors participating in the disaster site. 3) In the field of disaster, not only the disaster victims but also people related to entities are deprived of a stable living due to a long period of rescue activities. Furthermore, the conflicts derived from allocations of the aid fund can bring about the collapse of local community involved in disaster. 4) The life of the disaster victims that have been damaged mentally and financially is earnestly necessary to be conveniently served by disaster management service.

• Applied Chemistry for Engineering
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• v.32 no.6
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• pp.607-612
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• 2021

Silicon (Si) is one of the promising active materials to replace the widely used graphite because of its low electrochemical potential and high theoretical capacity. However, Si anodes still face in problems with the huge volume expansion and continuous decomposition of the electrolyte during repeated charge and discharge processes. To address these issues, a cross-linkable waterborne polyurethane (CWPU) based on a bio-oil, castor oil, was prepared and reacted with Tris(2,3-epoxypropyl) isocyanurate (TGIC) linkers, resulting in the formation of a mechanically robust 3D network structure. Si anodes fabricated with the CWPU-TGIC exhibited stable cycling performances and excellent discharge capacities. The results revealed that the CWPU-TGIC binder efficiently accommodates the large volume change for Si anode during charge and discharge cycles. Overall, the eco-friendly binder shows great promise in improving the electrochemical performances of Si anodes.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.6
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• pp.131-138
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• 2014

The steel structure fabrication plant certification program was enacted as a part of the construction technology management act, article 24-3, to improve the quality of steel construction after the decay falling accident of Seongsu Bridge in 1994. However, the national certification program for structural precast concrete that is a prefabricated construction products produced by casting concrete in plant is not implemented yet. So, to introduce the proper certification system for precast concrete, the quality certification programs of North America, Europe and Japan are surveyed. In North America, the organizations that manage the plant certification programs are PCI, NPCA, CPCI and so on. Sales of precast concrete elements in Europe are governed by the construction products regulation 305/2011. Therefore, CE marking is mandatory from July 2013 for all construction products including precast concrete. In Japan, precast concrete products used in civil engineering are certificated by JIS mark, product certification system and plants for manufacturing precast concrete building elements are audited by Japan Prefabricated Construction Suppliers and Manufacturers Association. Based on these survey studies, in this paper is described an adaptation of precast concrete plant certification to comport with the certification system in Korea.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.16 no.4
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• pp.369-376
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• 2003

In this paper, a nonlinear structural analysis for the composite structure composed of the spent nuclear fuel disposal canister and the 50㎝ thick bentonite buffer is carried out to predict the collapse of the canister while the horizontal symmetric sudden rock movement of 10㎝ is applied on the composite structure. This sudden rock movement is anticipated by the earthquake etc. at a deep underground. Elastoplastic material model is adopted. Drucket-Prager yield criterion is used for the material yield prediction of the bentonite buffer and von-Mises yield criterion is used for the material yield prediction of the canister(cast iron, copper). Analysis results show that even though very large deformations occur beyond the yield point in the bentonite buffet, the canister structure still endures elastic small strains and stresses below the yield strength. Hence, the 50㎝ thick bentonite buffet can protect the canister safely against the 10㎝ sudden rock movement by earthquake etc.. Analysis results also show that bending deformations occur in the canister structure due to the shear deformation of the bentonite buffer.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.30 no.6
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• pp.541-547
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• 2017

Climate change has become the main cause of the exacerbation in natural disasters. Social Overhead Capital(SOC) structure needs to be checked for displacement and crack periodically to prevent damage and the collapse caused by natural disaster and ensure the safety. For efficient structure maintenance, the optical image technology is applied to the Structure Health Monitoring(SHM). However, optical image is sensitive to environmental factors. So it is necessary to verify its validity. In this paper, the accuracy of estimating the vertical displacement was verified with respect to environmental condition such as natural light, measurement distance, and the number of image sheets. The result of experiments showed that the effect of natural light on accuracy of estimating vertical displacement was the greatest of all. The measurement angle which was affected by the change in measurement distance was also important to check the vertical displacement. These findings will be taken into account by applying appropriate environmental condition to minimize errors when the bridge was measured by camera. It will also enable the application of optical images to the SHM.