• Proceedings of the Korean Geotechical Society Conference
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• 2010.09c
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• pp.72-77
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• 2010

The Incheon Bridge, which was opened to the traffic in October 2009, is an 18.4 km long sea-crossing bridge connecting the Incheon International Airport with the expressway networks around the Seoul metropolitan area by way of Songdo District of Incheon City. This bridge is an integration of several special featured bridges and the major part of the bridge consists of cable-stayed spans. This marine cable-stayed bridge has a main span of 800 m wide to cross the vessel navigation channel in and out of the Incheon Port. In waterways where ship collision is anticipated, bridges shall be designed to resist ship impact forces, and/or, adequately protected by ship impact protection (SIP) systems. For the Incheon Bridge, large diameter circular dolphins as SIP were made at 44 locations of the both side of the main span around the piers of the cable-stayed bridge span. This world's largest dolphin-type SIP system protects the bridge against the collision with 100,000 DWT tanker navigating the channel with speed of 10 knots. Diameter of the dolphin is up to 25 m. Vessel collision risk was assessed by probability based analysis with AASHTO Method-II. The annual frequency of bridge collapse through the risk analysis for 71,370 cases of the impact scenario was less than $0.5{\times}10^{-4}$ and satisfies design requirements. The dolphin is the circular sheet pile structure filled with crushed rock and closed at the top with a robust concrete cap. The structural design was performed with numerical analyses of which constitutional model was verified by the physical model experiment using the geo-centrifugal testing equipment. 3D non-linear finite element models were used to analyze the structural response and energy-dissipating capability of dolphins which were deeply embedded in the seabed. The dolphin structure secures external stability and internal stability for ordinary loads such as wave and current pressure. Considering failure mechanism, stability assessment was performed for the strength limit state and service limit state of the dolphins. The friction angle of the crushed stone as a filling material was reduced to $38^{\circ}$ considering the possibility of contracting behavior as the impact.

• Journal of the Korean Institute of Gas
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• v.18 no.5
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• pp.6-11
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• 2014

To optimize the design of fuel cylinder for LNG vehicles, we introduced the design parameters of the inner and the outer tank of the vessel support structure by analyzing the structural characteristics of conventional design. We selected the inner and outer diameter of the hollow support bars and a dimension of the inner structure of the vessel among the design parameters for design optimization. In this study the temperature distribution and thermal stress of the support structure were evaluated by using the utility program as MSC/MARC. The evaluation criteria are first mode natural frequency, total transferred energy through support structure and thermal stress. The developed design satisfied the design criteria and it was made of prototype. The prototype was verified through three-dimensional vibration testing and thermal performance test.

• The Journal of the Acoustical Society of Korea
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• v.14 no.2E
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• pp.73-86
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• 1995

The transducer section of the forward-looking ultrasound imaging catheter (FLUIC) consists of a circular piezoelectric element as a vibrator and a conical acoustic mirror as a perfect reflector. A small diameter piezoelectric transducer element is mounted on the side of a catheter's rotating shaft. The unique design of FLUIC provides the capability to form a two-dimensional image of a cross-section of vessel in front of the catheter, which is lacking in the present generation of intravascular ultrasound (IVUS) transducers, as well as a conventional side view image. The mirror configuration for the transducer section of the FLUIC is designed using an approximated ray tracing techniques. The diffraction transfer function approach [1] developed for the field prediction from primary sources is generalized and extended to predict the secondary diffraction characterstics from an acoustic mirror. The extended model is verified by simulation and experiment through a simple plane reflector and employed to analyzed the field characteristics of a FLUIC.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.6 no.2
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• pp.34-41
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• 2010

This work is concerned with the analysis of stress corrosion cracking(SCC) behavior of Alloy 600 nozzle penetration mock-up according to a residual stress induced by a dissimilar metal welding(DMW) in a nuclear reactor pressure vessel. The effects of the dimension and materials of the nozzle penetration on the deformation and the residual stress induced by DMW were investigated using a finite element analysis(FEA). The inner diameter(ID) change of the nozzle by DMW and its dependance on the design variables, calculated by FEA, were well consistent with those measured from the mock-up. Accelerated SCC tests were performed for three mock-ups with different wall thicknesses in a highly acidic solution to investigate mainly the effect of the residual stress on the SCC behavior of Alloy 600 nozzle. From a destructive examination of the mock-up after the tests, the SCC behavior of the nozzle was fairly related with the residual stress induced by DMW : axial cracks were found in the ID surface of the nozzle within the J-weld region where the highest tensile hoop stress was predicted by FEA, while circumferential cracks were observed beyond both J-weld root and toe where the highest tensile axial stress was expected.

• Journal of Plant Biology
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• v.36 no.4
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• pp.345-355
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• 1993

Anatomical study of the secondary xylem in Araliaceous plants, induding 7 genera and 11 species grown in Korea, was carried out to elucidate the relationship among genera in the family. Wood of Hedera has difbse porous and shows ulmiform pattern of angular vessels, simple perforation plate, and alternate pitting. In addition, its ray is homogeneous type II with only procumbent ray cell. Ring porous wood of Dendropanax shows ulmiform of angular vessels, simple perforation plate, alternate pitting, and heterogeneous type II ray, which has sometimes horizontal secretory cavity. Fatsia has diffuse porous wood, which shows ulmiform of angular vessels, scalariform perforation plate (3-9 bars), scalariform pitting, spiral thickening in the lateral wall of vessel, and heterogeneous type II ray with sheath cells. Kalopanax has ring porous wood, which shows ulmiform of circular vessels, simple perforation plate and alternate pitting, and heterogeneous type II ray. While K pictum appears tylose with septum, K pictum var. maximowczii appears tylose without septum. Echinopanax shows ring porous wood, ulmiform of angular vessels, simple perforation plate, scalariform pitting, and tylose with septum. And the ray of Echinopanax is paedomorphic type I composed of only upright cells. Acanthopanax genus is composed of diffuse porous wood, ulmiform of angular vessels, simple perforation plate and alternate pitting. In this genus, A. sessiliflorus has heterogeneous type II ray, apotracheal axial parenchyma and tylose with septum. A. senticosus appears paedomorphic type I with only upright cells, and tylose with septum. A. koreanum and A. sieboldianum have heterogeneous type II ray but have not tylose. Aralia is composed of ring porous wood, ulmiform of circular vessels, simple perforation plate, alternate pitting, heterogeneous type II ray, and tylose contained both septum and reticulate. On the basis of arrangement, shape, length and diameter of vessel element, the angle of end wall to vessel axis, and ray type, the line of specialization in these genera is as follow: from Fatsia, the most primitive, to the most highly specialized Aralia, throughout Hedera, Acanthopanax, Echinopanax, Dendropanax, and Kalopanax by turns. turns.