• Journal of Korean Tunnelling and Underground Space Association
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• v.22 no.5
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• pp.543-561
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• 2020

This paper is the result of the study on the effect of the support structure of the tunnel steel rib. In tunnel excavation, the top and bottom half excavation methods result in subsidence of steel rib reinforcement due to insufficient support of steel rib reinforcement when the ground is poor after excavation. The foundation of the steel rib installed in the upper half excavates the bottom part of the base, causing the subsidence to occur due to various effects such as internal load and lateral pressure. As a result, the tunnel is difficult to maintain and its safety is problematic. To solve these problems, steel rib support structures have been developed. For the purpose of verification, the behavior of the supporting structure is verified by model experiments reduced to shotcrete and steel rib material similarity, the numerical analysis of ΔP and ΔP generated by bottom excavation by Terzaghi theoretical equation. As a result, it was found that the support structure of 20.100~198.423 kN is required for the 10~40 m section of the depth for each soil of weathered soil~soft rock. In addition, as a result of the reduced model experiment, a fixed level of 50% steel rib deposit of steel rib support structure was installed. The study shows that the installation of steel rib support structures will compensate for uncertainties and various problems during construction. It is also thought that the installation of steel rib support structure will have many effects such as stability, economy, and air reduction.

• Journal of the Korea Convergence Society
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• v.6 no.4
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• pp.9-14
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• 2015

This paper aims at solving the bending problem by the applied force due to the configuration of the neck part of guitar. At reinforcing and using the existing guitar, the method to understand the area vulnerable to the load was studied. In this study, the material property of wood applied to the practical guitar was applied and the finite element analysis was carried out after the modelling. By using the result through the study of this paper, it is thought that the foundation of material about bending and damage which has been recognized as the problem of existed guitar can be obtained. This study aims at improving the guitar as the design to reinforce it is studied. The bending and the damage are prevented and the durability can be improved by applying to the practical design on the basis of the result of the improved study model. And it is possible to be grafted onto the convergence technique at design and show the esthetic sense.

• The Journal of the Convergence on Culture Technology
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• v.7 no.2
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• pp.49-60
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• 2021

The purpose of this study was to examine the introduction of certification evaluation system for quality management of extracurricular program of Duksung Women's University. The research method was composed of two procedures, such as literature analysis and expert meetings. The contents of the study consisted of the accompanying conditions for the introduction of the certification evaluation system to implement the quality management of the extracurricular programs, which is operated in various ways in order to support the reinforcement of students' learning competencies at Duksung Women's University, according to a more formal level and a systematic flow. As a result of the study, the 「Regulations on the Evaluation of Extracurricular Program Certification」 is not only the main foundation for actualizing the link flow between continuous monitoring of extracurricular programs and annual performance evaluation, but also the common points for each university that is establishing the integrated management support system of comparative programs including Duksung Women's University.

• Structural Engineering and Mechanics
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• v.57 no.1
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• pp.1-20
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• 2016

On the basis of the geological conditions of high and steep mountainous slope on which an exit portal of an express railway tunnel with a bridge-tunnel combination is to be built, the composite structure of the exit portal with a bridge abutment of the bridge-tunnel combination is presented and the stability of the slope on which the express railway portal is to be built is analyzed using three dimensional (3D) numerical simulation in the paper. Comparison of the practicability for the reinforcement of slope with in-situ bored piles and diaphragm walls are performed so as to enhance the stability of the high and steep slope. The safety factor of the slope due to rockmass excavation both inside the exit portal and beneath the bridge abutment of the bridge-tunnel combination has been also derived using strength reduction technique. The obtained results show that post tunnel portal is a preferred structure to fit high and steep slope, and the surrounding rock around the exit portal of the tunnel on the high and steep mountainous slope remains stable when rockmass is excavated both from the inside of the exit portal and underneath the bridge abutment after the slope is reinforced with both bored piles and diaphragm walls. The stability of the high and steep slope is principally dominated by the shear stress state of the rockmass at the toe of the slope; the procedure of excavating rockmass in the foundation pit of the bridge abutment does not obviously affect the slope stability. In-situ bored piles are more effective in controlling the deformation of the abutment foundation pit in comparison with diaphragm walls and are used as a preferred retaining structure to uphold the stability of slope in respect of the lesser time, easier procedure and lower cost in the construction of the exit portal with bridge-tunnel combination on the high and steep mountainous slope. The results obtained from the numerical analysis in the paper can be used to guide the structural design and construction of express railway tunnel portal with bridge-tunnel combination on high and abrupt mountainous slope under similar situations.

• Journal of the Korean GEO-environmental Society
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• v.22 no.6
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• pp.5-15
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• 2021

One of the construction methods applied as a pier foundation type is a single type cast-in-place pile. In applying a pile bent system as a foundation type, the main concern in designing can be said to secure the lateral bearing capacity of pile structure in system. In addition, to increase the rigidity of the pile structure, a method of increasing the lateral bearing capacity by reinforcing the pile structure with a casing has been used. However, although the reinforcing effect and appropriate reinforcing length of casing may vary depending on the soil conditions, there is insufficient studies on this, and for this reason, the entire pile structure in a pile bent system is reinforced with a casing, in the field. In addition, if the length of the entire pile is reinforced with a casing, it may lead to delays in construction and increase in construction costs. That is, in order to more effectively reinforce the pile structure with a casing, it is necessary to study the lateral bearing characteristics of the reinforced pile structure in system. And it should be determined the appropriate reinforcing length of the casing from the evaluated bearing characteristics. Therefore, in this study, the lateral bearing characteristics of piles applied with the reinforcing length of casing for each condition were evaluated through a numerical analysis. And, based on the analysis results, the appropriate reinforcing length of casing was proposed. As a result of the study, it was found that in order to effectively increase the lateral bearing capacity of pile structure, the reinforcing length of casing should be applied twice the influence range of the bending behavior of the pile, 1/β.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.37 no.2
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• pp.209-215
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• 1992

Different from 'Seyokwiryang' (歲易爲良 : fallowing as the best method) which was an agricultural technique of ancient China, fertilization of rice fields was already practiced in the end of Koryo age in Korea. 'Bunjongbeob'(糞種法 : fertilizer applicating method on seed) or 'Bunkwabeob' (糞科法 : fertilizer applicating method on each plant) was practiced before green manure of bean crops and 'Bunjeonbeob'(糞田法 : fertilizer practicing method on fields) were done. In the 15th century 'Dojeonbunjeonbeob'(稻田糞田法 : fertilizer applicating method on paddy) in 'Jikseol' was divided the materials to be used into the soil brought from another place, trees, grasses, and the manure. Also, it discribed the fertilization between first plowing and the second, and proper fertilization for particular soil conditions. In case of transplanting techniques, the fertilization practices were specified into nursery and rice fields, and restoration of organic matter was systemized by plowing for cultivation in the reclaimed areas. In the 17th century, through 'Jikseolbo'($\ulcorner$直說補$\lrcorner$), the habitual practice of Kyungsang province was systemized and 'Bunyangsool'(糞壤術 : technique of fertilization) of 'Jodoangkicheo' (早稻秧基處 : rearing fields of early-ripening rice) was completed. Specific things was the manufacturing and utilizing techniques of 'Bunhoe'(糞灰 : mixture of manure and ash), 'Yohoe'(尿灰 : mixture of urine and ash), and additional fertilizers. In the 18 to 19th century, the materials of fertilization were greatly enlarged to recover the waste lands and to support the reinforcement of soil fertility for increasing the system of two cropping a year. Also, 'Jeobunbeob'(貯糞法 : method of manure storage) and additional fertilization were emphasized, and use of wagons for it was emphasized to improve the theory of fertilization and working efficiency. As mentioned above, limitation of fertilizing materials was conquered by 'Dojeonbunyang'(稻田糞壤 : techniques of practicing fertilizers in paddy) and the system of additional fertilization was established. The fertilization methods were improved with 'Jeobunbeob' due to the theory and recognition necessary for high rates of fertilizers.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.3
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• pp.677-683
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• 2016

In urban areas, underground tunnel construction sites have spread widely to accommodate rapidly increasing traffic volume along with a high-degree economic growth. Earth tunneling might be adapted frequently for the underground space securing, and various tunneling methods have been developed to stabilize the tunnel face and crown. Among them, the DSM (divided shield method) is gaining popularity for its enhanced stability and construction efficiency. This method has its foundation from the Messer Shield method, which is one of the trenchless special tunneling methods. This study examined the effects of face reinforcement on construction the sequence through a large scale soil chamber test and numerical analyses. The chamber has a size of a 1/2 scale of the real tunnel. Surface settlements were measured according the tunneling process. Commercially available software, MIDAS GTS, was used for numerical analysis and its result was compared with the values obtained from the chamber test. The results of the study show that both settlements of the embanked soils and the stress of the tunnel girder are located within the safe criteria. Overall, this study provides basic data and the potential of using a reinforced tunnel face to enhance DSM applications.

• Journal of the Korean Geotechnical Society
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• v.21 no.3
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• pp.149-157
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• 2005

In cases of the loosely accumulated ground and soft clayey soils, the settlement criterion usually governs in evaluating the stability of structures. The settlement is also a dominant factor to control the design of granular compaction piles mainly applied to the reinforcement of foundation structures in soft ground. In the previous studies, settlement behaviors of granular compaction piles have generally been analyzed with an evaluation of the settlement reduction factor based on the load-sharing ratio and the replacement ratio. In this approach, however, since the reinforced ground with granular compaction piles is simplified as the composite ground, only the difference of a relative vertical strength between piles and soils is taken into account without reflecting lateral behaviors of granular compaction piles. In the present study, the method of estimating the settlement of granular compaction piles is proposed by synthetically considering a vertical strength of the ground, lateral behaviors of granular compaction piles, the strength of pile materials, a pile diameter, and an installation distance of the pile. Further, far the verification of a validity of the proposed method, predicted settlements are compared with results from previous studies. In addition, parametric studies are performed together with detailed analyses of relevant design parameters.

• Journal of the Korean Geotechnical Society
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• v.15 no.6
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• pp.285-296
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• 1999

Preloading method is used to prevent the settling of a foundation and to increase the strength of ground by consolidation settlement in advance. But, the embankment used in preloading method brings large deformation and sliding failure in the soft ground. Recently, reinforcement method is often used in embankment in order to prevent sliding failure. But, until now, the research on the stability analysis considering both the rate of strength increase of clay by embankment load and increase of resistance force by the geosynthetics in the embankment body is not found. In this study, the stability analysis program(REAP) for embankment including these two points is developed. By this program(REAP), the stability analysis can be done about during the gradual increase of embankment and the stability counterplan can be established when the safety factor is lower than allowable safety factor of design. After calculating the position of sliding failure surface, the force of geosynthetics which is selected by either the effective tensile strength or tensile force caused by the displacement of soil mass in this position is applied to stability analysis. And the increase of resisting moment can be calculated by this force. Also, the construction period can be estimated and the time for the appropriate counterplan can be decided in order to maintain the stability of embankment. And then, safe and economical embankment design can be performed.

• Journal of the Korean GEO-environmental Society
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• v.16 no.7
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• pp.5-13
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• 2015

The pressure penetrating steel pipe pile method which can be constructed in a narrow space using the hydraulic jack is used on the foundation reinforcement, extension of the structure and basement, restoration of the differential settlement etc.. This method is possible to construct in narrow areas and low story height, the non-noise and non-vibration works, and it is possible for the construction site to be clean without slime. And it is possible to confirm the bearing capacity of pile due to penetrating the pile with the compression load of hydraulic jack. In this study, the static load test with the load-transfer test was carried out to investigate the bearing behavior characteristics of the pressure penetrating steel pipe pile. Four series of static load test were executed to investigate the variation of bearing behavior of the pressure penetrating steel pipe pile. As a result of these tests, the allowable load of the pressure penetrating steel pipe was evaluated more than 637 kN, and the shaft resistance corresponding to 81~86% of each applied load was mobilized with only a small portion of the base resistance acting. And it was also evaluated that the unit skin friction was mobilized to maximum value after two months.