• Transactions of the Korean Society of Mechanical Engineers B
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• 제31권4호
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• pp.313-319
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• 2007

The effect of capillary cross-section geometry on evaporation is investigated in terms of the meniscus shape, evaporation rate and evaporation-induced flow for circular, square and rectangular cross-sectional capillaries. The shapes of water and ethanol menisci are not much different from each other in square and rectangular capillaries even though the surface tension of water is much larger than that of ethanol. On the other hand, the shapes of water and ethanol menisci are very different from each other in circular capillary. The averaged evaporation fluxes in circular and rectangular capillaries are measured by tracking the meniscus position. At a given position, the averaged evaporation flux in rectangular capillaries is much larger than that in circular capillary with comparable hydraulic diameter. The flow near the evaporating meniscus is also measured using micro-PIV, so that the rotating vortex motion is observed near the evaporating ethanol and methanol menisci except for the case of methanol meniscus in rectangular capillary. This difference is considered to be due to the existence of corner menisci at the four comers.

• Journal of the Korean Society of Safety
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• 제31권3호
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• pp.68-74
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• 2016

This paper presents a new strengthening method of underground box structures against seismic loads for anti-seismic capacity improvement. A threaded steel member with pressure devices(so called 'Pre-flexed member system') is used to improve seismic capacity of the RC box structure. The pre-flexed member system is fixed the corner of opening after chemical anchor was installed by drilling hole on the box structure. The structural performance was evaluated analytically. Two bracing types of strengthening methods were used; conventional bracing method and I-bracing pressure system. For the performance evaluation, seismic analyses were performed on moment and shear resisting structures with and without strength member system. Numerical results confirmed that the proposed pre-flexed member system can enhance the seismic capacity of the underground RC box structures.

• Steel and Composite Structures
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• 제48권3호
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• pp.321-333
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• 2023

This paper proposes a comprehensive investigation on lateral stiffness of corner-supported steel modular frame using splice connection. A full-scale modular frame with two stacked steel modules under lateral load is tested. Ductile pattern in the transfer of lateral load is found in the final failure mode. Two types of lateral stiffness, including tangent stiffness and secant stiffness, are defined from the load-displacement due to the observed nonlinearity. The difference between these two types of stiffness is found around 20%. The comparisons between the experimental lateral stiffness and the predictions of classical methods are also conducted. The D-value method using hypothesis of independent case is a conservative option for predicting lateral stiffness, which is more recommended than method of contraflexural bending moment. Analyses on two classical short-rod models, including fix-rod model and pin-rod model, are further conducted. Results indicate that fix-rod model is more recommended than pin-rod model to simplify splice connection for simulation on lateral stiffness of modular frame in elastic design stage.

• Transactions of the Korean Society of Mechanical Engineers B
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• 제25권5호
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• pp.713-721
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• 2001

Characteristics of the conical vortices on the roof corner of a rectangular prism have been investigated by using a PIV(Particle Image Velocimetry) technique. The Reynolds number based on the free stream velocity and the height of the model was 5.3$\times$10$^3$. The mean, instantaneous velocity vector fields, vorticity fields, and turbulent kinetic energy distribution were measured for two different angles of attack, 30$^{\circ}$and 45$^{\circ}$. The PIV measurements clearly observed not only the conical main vortex and the secondary vortex but also the tertiary vortex which is firstly reported in this paper. Asymmetric formation of the corner vortex for the case of 30$^{\circ}$angle of attack produces relatively the high magnitude of vorticity and turbulent kinetic energy around the bigger vortex which generates the peak suction pressure on the roof. Fairly symmetric features of the roof vortex are observed in the case of 45$^{\circ}$angle of attack, however, the dynamic characteristics are proved to be asymmetric due to the rectangular shape of the roof.

• Journal of Navigation and Port Research
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• 제27권3호
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• pp.267-272
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• 2003

This paper describes design method of Passive-type Radar Reflector (PRR) which is to provide the requirement of newly revised 2000 SOLAS regulations on the Radar Reflector. The main target of this work is to find the optimum shape of a radar target having large Radar Cross Section (RCS). Through the RCS analysis based on the theoretical approach, two kinds of PRR models, RRR-F model for use in fisheries and PRR-S model for use in small sized ship, are designed and discussed their RCS performance. RCS measurement tests for the various sized samples are carried out in an anechoic chamber. As evaluation results it was clearly shown that the conventional sphere-type shows optimum shape in case of PRR-S, while the cylinder-type which consists of large sized corner clusters or zig-zag flat plats gives best performance in case of PRR-F.

• Journal of the Korea Institute of Military Science and Technology
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• 제18권5호
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• pp.510-516
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• 2015

This paper describes an approach to detect interesting objects using satellite images. This paper focuses on the interesting objects that have common special patterns but do not have identical shapes and sizes. The previous technologies are still insufficient for automatic finding of the interesting objects based on operation of special pattern analysis. In order to overcome the circumstances, this paper proposes a methodology to obtain the special patterns of interesting objects considering their common features and their related characteristics. This paper applies MSER(Maximally Stable Extremal Regions) for the region detection and corner detector in order to extract the features of the interesting object. This paper conducts a case study and obtains the experimental results of the case study, which is efficient in reducing processing time and efforts comparing to the previous manual searching.

• Journal of Trauma and Injury
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• 제28권4호
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• pp.280-283
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• 2015

The adolescent Tillaux fracture is an avulsion fracture of the anterolateral corner of the distal tibial epiphysis caused by external rotation of the foot. This type of fracture occurs during epiphyseal fusion in adolescence. A difficult to detect Tillaux fracture was discovered on a preoperative radiograph, such fractures have rarely been reported to accompany a predominantly adult-type ankle fracture. Especially, to the best of our knowledge, no case of a trimalleolar ankle fracture in an adolescent with a Tillaux fracture has been reported. Thus, we present a case of a trimalleolar ankle fracture in a 15-year-old adolescent with a Tillaux fracture who was successfully treated surgically.

• Asia Pacific Journal of Business Review
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• 제2권2호
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• pp.45-59
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• 2018

Globalization is swapping the every possible corner of the globe steadily yet gradually. Mammoth like companies are penetrating the threshold of potential nations as freelancers and exploiting every inch of feasibility to carry out commercial activities. Undoubtedly, the entire world is experiencing the glare of new horizon. Even laggards nations are also turning out to be a country of immense potential and dynamism. They too, have awakened miserably to comprehend their self worth and entity while bearing the torch of Globalization. The shed of globalization have not only sprinkled capitalistic or mercantilist but even countries like China - once a hardcore communist country is also not remaining untouched with it. Albeit, the Dragon responding affirmatively to the hot current of Globalization yet their way is un-orthodoxical, strange and inventive. This case study discussed on major areas where India, the largest democracy in the world and six largest economy in the world are facing steep competition from China.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 한국공작기계학회 2002년도 추계학술대회 논문집
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• pp.90-94
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• 2002

In this paper, Compression in the case where dissimilar blocks are twinned variously are carried out in the condition of lubricated interface. The degree of growth is experimentally investigated. Moreover, numerical simulations are carried out by the elastic-plastic FEM for the case of the dissimilar blocks with the initial sawtooth angle of 60。. The dissimilar blocks are twinned, larger difference between material properties leads smaller growth, and the degreased interface leads smaller growth than that in the lubricated one. Furthermore, by the simulation of compression where dissimilar blocks are twinned, it is confirmed that the tendency of the general deformation pattern is very similar to the experiment.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2006년도 제32회 KOSCO SYMPOSIUM 논문집
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• pp.96-104
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• 2006

In the present paper, the effects of combustion instability on flow structure and flame dynamic with the configurations of burner exit in a model gas turbine combustor are investigated using large eddy simulation(LES). A G-equation flamelet model is employed to simulate the unsteady flame behavior. As a result of mean flow field, the change of divergent half angle(${\alpha}$) at burner exit results in variations in the size and shape of the central toroidal recirculation(CTRZ) as well as flame length by changing corner recirculation zone(CRZ). The case of ${\alpha}=45^{\circ}$ show smaller size and upstream location of CTRZ than that of $90^{\circ}$ and $30^{\circ}$ by the development of higher swirl velocity. The flame length in the case of ${\alpha}=45^{\circ}$ is the most shortest, while that in the case of ${\alpha}=30^{\circ}$ is the longest by the decrease of effective reactive area with the absence of CRZ. Through the analysis of pressure fluctuation, it is identified that the case of ${\alpha}=45^{\circ}$ shows the most largest damping effect of pressure oscillation in all configurations and brings in the noise reduction of 2.97dB, comparing with that of ${\alpha}=30^{\circ}$ having the largest pressure oscillation. These reasons are discussed in detail through the analysis of unsteady phenomena about recirculation zone and flame surface. Finally the effects of flame-acoustic interaction are evaluated using local Rayleigh parameter.