• 해양환경안전학회지
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• 제20권3호
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• pp.296-303
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• 2014

The Axiom propeller is a unique 3 bladed propeller and it enables to generate the same amount of thrust going ahead as it does going astern because of its 's' type skew-symmetric blade section. A earlier variant of the design (Axiom I propeller) performed a low propeller efficiency, maximum 35 % efficiency, and further blade outline design was carried out to achieve a higher efficiency. The optimized new blade outline (Axiom II propeller) has more conventional Kaplan geometry shape than Axiom I propeller. Model tests of open water performance and propeller cavitation for both propellers were conducted at Emerson Cavitation Tunnel in order to compare their performances. Experiment results revealed that Axiom II propeller provides a maximum 53 % efficiency and provides better efficiency and cavitation performance over the Axiom I propeller under similar conditions.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1998년도 가을 학술발표회 논문집
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• pp.413-420
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• 1998

In this study, an expert system is developed to evaluate a safety of tunnel structures. Using a dynamic finite element analysis module, this expert system predicts dynamic responses of a concrete lining surface which a transient force is applied on and estimates the condition between the concrete lining and surrounding ground. The evaluation parameter values of the module are multi-reflected wave frequency and amplitude of the dynamic responses. The multi-reflected wave frequency represents the depth of concrete lining, and the other parameter, the amplitude of the frequency, is utilized for detecting the internal flaws. A comparison of the dynamic responses between numerical and experimental model test verifies an effectiveness of this system. By this expert system, the safety of tunnel structures and the detection of internal flaws of concrete linings are estimated quantitatively.

• 한국기계기술학회지
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• 제20권6호
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• pp.929-935
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• 2018

This paper develops a flow control block for a hydraulic system of a tunnel boring machine. The flow control block is a necessary component to ensure stability in the operation of the hydraulic system. In order to know the pressure distribution of the flow control block, the flow analysis was performed using the ANSYS-CFX. It was confirmed that the pressure and flow rate were normally supplied to the hydraulic system even if one of the four ports of the flow control block was not operated. In order to evaluate the structural stability of the flow control block, structural analysis was performed using the ANSYS WORKBENCH. As a result, the safety factor of the flow control block is 1.54 and the structural stability is secured.

• 대한안전경영과학회지
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• 제24권4호
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• pp.95-100
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• 2022

In general, fire accidents in tunnels are sufficiently preventable, but the damage is very large. Therefore, the number of highway traffic accidents is high in spring when spring fatigue occurs and the traffic volume for maple travel increases. In particular, when analyzing the cause of death of people killed in fire accidents in tunnels, it is analyzed that most of them are suffocated by smoke. Therefore, in this study, it can be said that it is meaningful to make a social contribution to reduce the number of traffic accident deaths by establishing an efficient fire suppression system for fire accidents in tunnels.

• Structural Engineering and Mechanics
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• 제57권1호
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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.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1993년도 지하공간 건설기술에 관한 서울 심포지움 논문집
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• pp.103-118
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• 1993

The application of T.B.M tunnelling has been progressively increased since the first entrance into Korea in 1985 and especially, its higher performance and safety is widely proved as a generalized tunnelling in hardrock tunnel construction, comparing wi th conventional method. This case announcement will be much helpful for your general understanding of T.B.M tunnelling and the development of tunneling technology by introducing the brief methods and construction results from the actual application cases of T.B.M tunnelling in Ulsan Water Supply Tunnel Project, the longest tunnel in Korea under construction by YOU ONE. Co.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1990년도 PROCEEDINGS OF THE FIRST KOREA-JAPAN JOINT GEOTECHNICAL SEMINAR ON EXCAVATION and TUNNELING IN URBAN AREAS
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• pp.25-34
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• 1990

For the construction of twin single track subway tunnels by NATM within close proximity of existing vehicle underpass in the highly congested area of downtown Seoul, finite element analyses were performed to evaluate the ground responses during tunnelling and also the stability and safety of the underpass structure and subway tunnels. Results of the analyses indicated the need to improve the soil beneath the underpass, and pre-grouting was carried out prior to the tunnel excavation. During tunnel construction field measurement program was implemented to confirm the results of anslyses and to control the tunnel construction procedures, thus ensuring stability of the existing structres.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 A
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• pp.346-348
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• 2001

This paper analyze the interference problems, especially AC corrosion when the gas pipeline is buried with power cable in the same submarine tunnel. This paper present the results of the study about AC corrosion, limitation of safety voltage, modeling of power cables, gas pipeline and grounding systems, analysis of induction voltage according to various circumstance, soil resistivity, length of tunnel. and so on.

• 화약ㆍ발파
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• 제17권4호
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• pp.67-88
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• 1999

터널굴착으로 발생되는 지반침하는 지상구조물의 변형을 유발할 수도 있으므로 터널굴착전에 지상구조물의 안전성 평가가 선행되어야 한다. 이러하여 본 연구에서는 전문가의 포함된 터널현장의 지표침하를 예측하고, 이를 기반으로 지상구조물의 안전성 평가를 수행하는 전문가 시스템 NESSS(Neural network Export System for Adjacent Structure Safety Analysis)를 개발하였다. NESASS는 인공신경망을 이용하여 기존 터널현장의 지표침하 계측자료로 작성된 데이터베이스 자료를 학습자료로 하여 학습을 수행하고, 이를 기반으로 터널현장의 지표침하 트라프를 추론한다. 또한 추론된 지상구조물 기초부 변형을 기반으로 계산된 평가 매개변수(angular distortion 등)의 혀용 한계치를 이용하여 건물의 안전성을 평가하고 Dulacska의 균열평가 모델을 이용하여 지상구조물의 균열양상을 예측한다. 따라서, 본 연구에서는 지표침하의 주 영향인자들을 선정하고 이를 분류항목으로 이용, 서울지하철 일부구간의 지표침하 계측자료를 수집, 정리하여 데이터베이스화를 추진하였다. 그리고 인공신경망 구조에 관련된 매개변수 연구를 수행하여 개발된 NESASS의 인공신경망 구조의 신뢰도를 확인하였으며 기수행된 침하계측 결과치와 비교하여 지표침하 예측능력도 조사하였다. 또한 NESASS를 이용하여 실제 터널현장을 모델로 설정, 지상구보물의 안전성 평가를 수행해 봄으로써 NESASS의 실무적용성을 아울러 확인하였다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1997년도 가을 학술발표회 논문집
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• pp.141-150
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• 1997