• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.5
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• pp.724-733
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• 2003

Fatigue design rules for welds in the ASME Boiler and Pressure Vessels Code are based on the use of Fatigue Strength Reduction Factors(FSRF) against a code specified fatigue design curve generated from smooth base metal specimens without the presence of welds. Similarly, stress intensification factors that are used in the ASME B3l.1 Piping Code are based on component S-N curves with a reference fatigue strength based on straight pipe girth welds. But the determination of either the FSRF or stress intensification factor requires extensive fatigue testing to take into account the stress concentration effects associated with various types of component geometry, weld configuration and loading conditions. As the fatigue behavior of welded joints is being better understood, it has been generally accepted that the difference in fatigue lives from one type of weld to another is dominated by the difference in stress concentration. However, general finite element procedures are currently not available for effective determination of such stress concentration effects. In this paper, a mesh-insensitive structural stress method is used to re-evaluate the S-N test data, and then more effective method is proposed for pressure vessel and piping fatigue design.

• Korean Journal of Ichthyology
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• v.9 no.2
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• pp.244-247
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• 1997

A specimen of carangid fish, Seriola rivoliana Valenciennes belonging to the family Carangidae was collected for the first time in Pusan, Korea. It was similar to Seriola dumerili (Risso) by appearance, but differed in some morphological characters having the deeper body, the higher lobes of the second dorsal and anal fins, becoming straight line below 23-24th ray of second dorsal fin, the configuration of the first haemal spine. A new Korean name "Nat Jaetbang-eo" is proposed for this species.

• Journal of Advanced Marine Engineering and Technology
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• v.35 no.4
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• pp.500-505
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• 2011

In this paper, two types of micro-optic submersion detection systems are proposed and demonstrated. The structures are based on the transmission and reflection of incident light, respectively. Two collimators are separated by 10 mm and installed face to face in straight line. The incident light transmits from one side of collimator to the other through the air, but the optical loss is below 1 dB. On the other hand, when the sensors are submersed into water, most of optical power scattered into water. The systems monitor the dramatical power change to alarm the submersion. Reflection type of sensor system has a Bragg grating at the end of the sensor for back-reflection of sensing signal. This is for simple configuration of systems. The performance of two sensor systems are described in detail.

• Magazine of the Korea Concrete Institute
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• v.8 no.3
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• pp.147-155
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• 1996

In this study a model for the constitutive relation of a plane concrete is proposed using a micromechariical model. In this model a precursor crack is assumed to exist in the aggregate-cement paste interface, and the LEFM is used to predict the nucleation of the bond cracks and the grow th of mortar cracks. For computational convenience the bond crack-mortar crack configuration is transformed into a straight crack with a point force in the middle. 'The overall compliance and the cons,titutive relation are predicted from the damage due to microcracks, and the predicted stress-strain curves are compared with some experimental data. According to the results, the model predictions are better for under tensile loading than under compression, for high, strength concrete than for normal strength concrete.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.5
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• pp.1725-1734
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• 1996

Experimental condensation and evaporation heat transfer coefficients were measured in a horizontal smooth tube and a horizontal micro-finned tube with HFC-134a. The test sections are straight, horizontal tubes with have a 9.52mm outside diameter and about 5000mm long. The micro-finned tube had 60 fins with a height of 0.12mm and a spiral angle of 25.deg.. The condensation test section was a double-pipe type with counter flow configuration. The evaporation test section employed an electic heating method. Enhancement factors which is defined as a ratio of the heat transfer coefficient for micro-finned tube to that for smooth tube, varied from 1.3 to 1.6(mass flux:110~190kg/m$^{2}$s) for condensation and 1.2 to 1.5 (mass flux:70~160kg/m$^{2}$s) for evaporation. The experimental data of condensation and evaporation heat transfer coefficients were compared to several empirical correlations. Based on these comparisons, modified correlations of the condensation and evaporation heat transfer coefficient for both smooth and micro-finned tubes were proposed.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.11
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• pp.343-346
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• 1997

A new type of stent was invented using a Nitinol wire. The hoop strength of the new stent was found to be 2 times larger than that of the Cragg or Memotherm stents. However, the longitudinal flexibility of the new stent was inferior to both the Cragg and Memotherm stents. This new stent seems to be useful or the treatment of stenosis with straight configuration, but need to be improved or use in tortuous stenotic region. The stent was applied to the patients with esophargeal stenosis and showed a good result.

• Journal of the Society of Naval Architects of Korea
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• v.29 no.1
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• pp.55-60
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• 1992

A study has been made on the hydrodynamic forces on and the motion response of a sliding block in a bay within the framework of linear potential theory. To simplify the problem, following assumptions are made : The configuration of the bay is a long channel with narrow width, constant depth and straight coastline. Incident waves are long compared to the depth. We applied matched asymptotic expansion techniques. The flued domain is subdivided into three regions ; ocean, bay entrance, bay regions. Boundary-vague problems are solved first in each region. Then unknown coefficients are determined by matching individual solutions at the intermediate region between two neighboring legions. It is found that the motion of the block is greatly amplified at the resonant frequencies, in particular at the quarter wavelength mode. We examined the mechanism of negative added mass, which results from the localized hydrodynamic resonance.

• Geotechnical Engineering
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• v.8 no.3
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• pp.5-12
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• 1992

This paper performs a study on the influences of shape and installation method on the ultimate uplift capacity of model piles in sand. Several model piles of different shape, such as straight sided, single-underreamed, multi-underreamed and anchor plate are used. The effects of installation method are studied with buried, driven and vibrotriven piles. Based on model test results, it has been found that when the foundation is subjected to atrial up- lift and compressive load as well, a single-underreamed pile is most effective. When the loading is axial uplipt only, it is likely that anchor plate would be most efficient. Installation method and tip configuration of pile have significant influnce on uplift resistance.

• Earthquakes and Structures
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• v.16 no.5
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• pp.533-546
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• 2019

This study presents an experimental investigation on six beam-column joint specimens under the lateral cyclic loading. The aim was to explore the effectiveness of steel fiber-reinforced concrete (SFRC) in reducing the transverse shear stirrups in beam-column joints of the reinforced concrete (RC) frames with strong-columns and weak-beams. Two RC and four SFRC specimens with different types of reinforcement detailing and steel fibers of volume fraction in the range of 0.75-1.5% were tested under gradually increasing cyclic displacements. The main parameters investigated were lateral load-resisting capacity, hysteresis response, energy dissipation capacity, stiffness degradation, viscous damping variation, and mode of failure. Test results showed that the diagonally bent configuration of beam longitudinal bars in the beam-column joints resulted in the shear failure at the joint region against the flexural failure of beams having straight bar configurations. However, all SFRC specimens exhibited similar lateral strength, energy dissipation potential and mode of failure even in the absence of transverse steel in the beam-column joints. Finally, a methodology has been proposed to compute the shear strength of SFRC beam-column joints under the lateral loading condition.

• Korean Journal of Ichthyology
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• v.33 no.3
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• pp.196-201
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• 2021

The Indo-West Pacific pipefish, Hippichthys penicillus was newly recorded from Korean waters based on a single specimen (124.5 mm SL) collected from a lower reach of creek of the Namhaedo Island flowing into Dongdae Bay. It is separable from congeners in having a longer snout and unique configuration of principle body ridges including discontinuous superior trunk and tail ridges and straight lateral trunk ridge ending near anus. A new Korean name, "Huin-jeom-sil-go-gi", is proposed for the species.