• Journal of Industrial Technology
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• v.25 no.B
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• pp.115-120
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• 2005

Impact seismic wave method is a method for non-destructive testing of concrete structure using of stress wave which is propagate and reflected from internal flaws within concrete structure and external surface. In this study, we performed frequency domain method using impact seismic wave test for safety diagnosis of civil engineering structure. And reflection method which is used for one-dimensional target such as tunnel lining and transmission method are compared with each other.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2002.05a
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• pp.27-30
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• 2002

Contemporary architecture calls for a wide range of surface textures and treatments. A surface compatible with the architect's design may vary from a glass-smooth finish to one requiring special sculptured ornamentation. These surfaces require many different types of form sheathing and lining. The purpose of study development new design form and made elaborateness shape. Easy to used in field that architecture finish material not used expect effective reduce of working hours, personnel expenses, architecture finish material, cost. After this, building wall apply a variety shape in concrete surface.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.11a
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• pp.565-568
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• 2003

Contemporary, architecture calls for a wide range of surface textures and treatments. A surface compatible with the architecture's design may vary from a glass-smooth finish to one requiring special sculptured ornamentation. These surfaces require many different types of form sheathing and lining. The purpose of study development new design form and made elaborateness shape. Easy to used in field that architecture finish material not used expect effective reduce of working hours, personnel expenses, architecture finish material, cost. though this study, we have figured out the best mix proportion for durability and glossability of glossing exposure concrete.

• Proceedings of the Korean Geotechical Society Conference
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• 2001.03a
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• pp.49-56
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• 2001

The techniques to make assessment of the structural integrity of underground structures include Infrared thermagraphy, GPR using the reflection of the electromagnetic wave, ultrasonic test, seismic methods using the propagation of elastic wave, and etc These methods have pros and cons in the assessment of the structural integrity in the complex environment of the underground structure, so that a single method alone is not enough to evaluate parameters required for the assessment. In this study, a new seismic method was proposed to improve the existing methods and to provide an additional information like stiffness of concrete. The proposed method combines the advantages of the modified impact-echo test and the SASW method. To verify the validity of the proposed method, a large scale model of a tunnel concrete liner was built and the proposed method was applied to the center of the model and also to the corner of the model which has several distinct reflection boundaries.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.22 no.1
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• pp.81-89
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• 2024

Highly radioactive waste is solidified to restrict leaching, retain its shape, and maintain its structural stability to prevent it from affecting humans and the environment as much as possible. This operation should be performed consistently regardless of whether the waste is homogeneous or heterogeneous. However, currently, there are no specific performance requirements for heterogeneous waste in Korea. This study reviewed domestic research results and the status of overseas applications, and proposed immobilization requirements for heterogeneous waste to be applied in Korea. IAEA safety standards, domestic laws, and waste acceptance criteria were reviewed. The status of heterogeneous waste immobilization in countries such as the United States, France, and Spain was reviewed. Most countries treat heterogeneous waste by encasing it in concrete, and impose immobilization requirements on this concrete. Based on these data, safety standards for the thickness, compressive strength, and diffusion limit of this concrete material were proposed as immobilization requirements for heterogeneous waste disposal in Korea. Quantitative values for the above requirements need to be derived through quantitative assessments based on the characteristics of domestic heterogeneous waste and disposal facilities.

• Journal of Korean Tunnelling and Underground Space Association
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• v.26 no.5
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• pp.507-518
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• 2024

In general, the tunnel portal is constructed with reinforced concrete. And the carbonation of concrete can cause reinforcement corrosion, causing function failure and tunnel destruction. To establish management system such as tunnel inspection and rehabilitation, distance between tunnel portal and coast, service life and traffic were selected as carbonation influencing factors and correlation analysis with carbonation depth for each influencing factor was performed.

• Smart Structures and Systems
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• v.32 no.4
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• pp.195-205
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• 2023

The contact acoustic emission (AE) monitoring system is time-consuming and costly for monitoring concrete structures in large scope, in addition, the great difference in acoustic impedance between air and concrete makes the detection process inconvenient. In this work, we broaden the conventional AE source localization method for concrete to the non-contact (air-coupled) micro-electromechanical system (MEMS) microphones array, which collects the energy-rich leaky Rayleigh waves, instead of the relatively weak P-wave. Finite element method was used for the numerical simulations, it is shown that the propagation velocity of leaky Rayleigh waves traveling along the air-concrete interface agrees with the corresponding theoretical properties of Lamb wave modes in an infinite concrete slab. This structures the basis for implementing a non-contact AE source location approach. Based on the experience gained from numerical studies, experimental studies on the proposed air-coupled AE source location in concrete slabs are carried out. Finally, it is shown that the locating map of AE source can be determined using the proposed system, and the accuracy is sufficient for most field monitoring applications on large plate-like concrete structures, such as tunnel lining and bridge deck.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.417-422
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• 2005

The appropriate ventilation system in vehicular tunnel should be the most economical solution with regard to both construction and maintenance. The damages on tunnel lining was affected by formula of ventilation system in long vehicular tunnel. In this study, carbonation, one of main experimental items in precision safety diagnosis, was analyzed by contouring damage area with ventilation system. Considerations of carbonation were also given to the design and maintenance which manage the long-term safety in tunnel.

• Geomechanics and Engineering
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• v.36 no.1
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• pp.1-8
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• 2024

We propose a new method for detecting voids behind tunnel concrete linings using the impact-echo method that is based on continuous wavelet transform (CWT) and a convolutional neural network (CNN). We first collect experimental data using the impact-echo method and then convert them into time-frequency images via CWT. We provide a CNN model trained using the converted images and experimentally confirm that our proposed model is robust. Moreover, it exhibits outstanding performance in detecting backfill voids and their status.

• Journal of the Korean Geotechnical Society
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• v.18 no.6
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• pp.153-160
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• 2002

A new system identification method based on tunnel deformation data is proposed to find the damage in the lining structure. For this, an inverse problem in which the deformation data and dead load of concrete lining are known a priori is introduced to estimate the degree and location of the damages. Models based on uniform reduction of stiffness and homogenized crack concept are individually employed to compare the applicability and relative advantages of the models. Numerical analyses are peformed for the idealized tunnel structure and the effect of white noise, common in most measurement data, is also included to better understand the suitability of the proposed models. As a result, model 1 based on uniform stiffness reduction method is shown to be relatively insensitive to the noise, while model 2 with the homogenized crack concept is proven to be easily applied to the field situation since the effect of stiffness reduction is rather small.