• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.36 no.4
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• pp.329-336
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• 2000

Welding is a important technological method in mechanical engineering. $CO_2$MAG(metal active gas) welding means that metal part in double capstan drum for the inshore and costal vessels are joined by melting(with or without a filler material) or that new material is added to a metal part by melting. The thermal stresses appear due to a non-uniform temperature field, inhomogeneous material properties, external restraint and volume changes during phase transformations. In this study analysis the elasto-plastic thermal stresses distribution of welding part in double capstan drum for the inshore and costal vessels using finite element method (FBM). Therefore it calculates the numerical value that can be applied to the optimum design of welding parts and the shapes. The significant results obtained in this study are summarized as fellows. At early stage of the cooling after welding process, the abrupt thermal stresses gradient has been shown in the vicinity of welding part. In the thermal stresses analysis due to temperature gradient and heat shocking maximum stress was occurred of welding part and stresses were distributed from 54MPa~48MPa.

• International Journal of Highway Engineering
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• v.11 no.3
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• pp.61-74
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• 2009

Traffic accident risk index Computation model's development apply traffic level of significance about area of road user group, road and street network area, population group etc.. through numerical formula or model by countermeasure to reduce the occurrence rate of traffic accidents. Is real condition that is taking advantage of risk by tangent section through estimation model and by method to choose improvement way to intersection from outside the country, and is utilizing being applied in part business in domestic. However, question is brought in the accuracy being utilizing changing some to take external model in domestic real condition than individual development of model. Therefore, selection intersection estimation element through traffic accidents occurrence present condition, geometry structure, control way, traffic volume, turning traffic volume etc. in 96 intersections in this research, and select final variable through correlation analysis of abstracted estimation elements. Developed intersection design model taking advantage of signal type, numeric of lane, intersection type, analysis of variance techniques through ANOVA analysis of three variables of intersection form with selected variable lastly, in signal crossing through three class intersection, distinction variable choice risk in model, no-signal crossing risk distinction analysis model and so on develop.

• Journal of Environmental Science International
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• v.13 no.12
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• pp.1049-1058
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• 2004

PM10 concentration of total 48 samples collected from 4 sites (the root of Miryang University, Sangnam township Office in Miryang. the root of Changwon elementary school, and Junam reservoir in Changwon) turned out to range from 42.29 to 69.49{\mu}g/m^{3}$, and the average concentration was the root of Changwon elementary school $(69.49{\mu}g/m^{3})$>the root of Miryang university $(58.59{\mu}g/m^{3})$>Junam reservoir $(43.56{\mu}g/m^{3})$>Sangnam township Office $(42.29{\mu}g/m^{3}).> In particular, Junam reservoir, the Clean Area, had a slightly higher value than Sangnam township Office. It was thought although the site was plane and windy without pollutants around. it had a higher concentration value influenced by external factors including bigger population and a northeasterly wind due to a newly-established industrial complex nearby. As for water-soluble ions among PM10 particle collected in Miryang and Changwon area, SO42- accounted for $50{/%}$ and NO3-, was $35{\%}$, and the concentration order was S042->N03->Cl->F-. As for the average concentration of metallic components among PM10 particle collected in Miryang and Changwon area. the root of Changwon elementary school had the AI concentration, Fe concentration and Zn concentration 4 times, 3 times and 1.5 times that of Junam reservoir, respectively. The root of Miryang University had the AI concentration 2 times that of Sangnam township Office, and had Fe concentration and Zn concentration $1.2\~1.5$ times those of Sangnam township Office. When it comes to the relation between metallic elements and meteorological factors in Changwon area, the highest coefficient of correlation was between temperature and humidity with 0.92, and temperature and wind speed turned out in the reverse correlation. The coefficient of correlation between Al and Cr was as high as 0.78. Among metallic elements, the coefficient of correlation between Cu and Pb, Cd, Al were 0.84, 0.85, 0.79, respectively. It is thought that the high coefficient of correlation between Cu and Pb is ascribed to busy traffic and wind in the urban areas, Sammun-dong and Gagok-dong in Miryang. Meanwhile, the coefficients of correlation between Fe and Cu, Al, Zn, Cd, Pb were in the reverse correlation. These coefficients of correlation are attributed to the difference in pollutant sources, rather than difference in pollutant and non-pollutant.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.3
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• pp.307-313
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• 2010

In this study, alternative designs for the bends used in district heating pipes are investigated. The district heating pipes, which are subjected to temperatures of 10 to $120^{\circ}C$ and a water pressure of $16\;kgf/cm^2$, have to withstand thermomechanical cyclic loads when in use. These pipes comprise three concentric tubes: a steel pipe (internal), polyurethane (PUR) insulator (middle), and a high-density polyethylene (HDPE) case (external). In addition, the bends in the district heating pipe system are covered with foam pads that cause aging. In this study, an alternative bend design that does not involve the use of a foam pad is proposed to overcome the aging problem in the bends. In the proposed design, "shear rings" are added to the surface of a bend, and its dimensions are determined by a combination of the statistical (Taguchi) method and FEM. The geometrical parameters such as thickness, height, and number of the rings significantly affect the design optimization, and hence, they affect the results of the FEM.

• Journal of Radiation Protection and Research
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• v.17 no.1
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• pp.43-56
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• 1992

As one of the methods to ameliorate the ray effects which are the nature of anomalous computational effects due to the discretization of the angular variable in discrete ordinates approximations, a computational program, named TWODET (TWO dimensional Discrete Element Transport), has developed in 2 dimensional cartesian coordinates system using the discrete elements method, in which the discrete angle quadratures are steered by the spatially dependent angular fluxes. The results of the TWODET calculation with K-2, L-3 discrete angular quadratures, in the problem of a centrally located, isotropically emitting flat source in an absorbing square, are shown to be more accurate than that of the DOT 4.3 calculation with S-10 full symmetry angular quadratures, in remedy of the ray effect at the edge flux distributions of the square. But the computing time of the TWODET is about 4 times more than that of the DOT 4.3. In the problem of vacuum boundaries just outside of the source region in an absorbing square, the results of the TWODET calculation are shown severely anomalous ray effects, due to the sudden discontinuity between the source and the vacuum, like as the results of the DOT 4.3 calculation. In the probelm of an external source in an absorbing square in which a highly absorbing medium is added, the results of the TWODET calculation with K-3, L-4 show a good ones like as, somewhat more than, that of the DOT 4.3 calculation with S-10.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.825-831
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• 2017

In this study, we perform the design of dome geometry for the composite pressure vessel with applying the equation of Fulton and Vasiliev considering external load(thrusts). Variables of the dome geometry are opening radius ratio(${\rho}_0$) from 0.1 to 0.5 and thrust level from 40kN to 200kN. We conduct Finite Element Analysis(FEA) by using ABAQUS. As a result, the strain of the composite pressure vessel has shown strain gradient from inner to outer of dome surface. And the strain gradient may cause crack of resin inside the composite laminate. Strain gradient of Fulton dome is monotonously decreased as the ${\rho}_0$ increases, but the strain gradient of Vasiliev dome bas shown some different trend. when ${\rho}_0{\leq}0.1$, strain gradient of Fulton's is higher than Vasiliev's. But when 0.1<${\rho}_0$<0.35, strain gradient of Vasiliev's becomes higher than Fulton's. And in the case of $0.35{\leq}{\rho}_0$, strain gradient of Vasiliev's is higher than Fulton's. So the Vasiliev dome is more effective in ${\rho}_0{\leq}0.1$ condition and Fulton dome is more effective in $0.35{\leq}{\rho}_0$ condition. So, it's important for dome design to consider the crack of resin cause of the strain gradient.

• 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 Korea Academia-Industrial cooperation Society
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• v.17 no.5
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• pp.173-178
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• 2016

When a ballast track of a high-speed train is constructed on a bridge, the displacement of the bridge decks can occur because they are not fixed to the rails. Moreover, relative displacements occur between the bridge and rails caused by temperature changes and external loads. The current longitudinal resistance criteria (UIC Code 774-3, KR C-08080) on ballast tracks with continuous welded rails (CWRs) do not take into account the longitudinal movement of the bridge and the frictional force between the ballast and slabs. In addition, the magnitude of the longitudinal resistance, k, is calculated somewhat conservatively and, (therefore?) it acts as an unfavorable element in the design of long span and continuous railway bridges. Thus, in order to replicate the actual behavior more effectively, the longitudinal resistance of CWRs should take into account the additional rigidity between the slab and track. In this study, the longitudinal resistances of the ballasted track on the bridge were analyzed by carrying out an experimental study with a test setup designed to simulate the deck and bed track. In the test results, the maximum longitudinal resistances of the tests were similar to the resistances of the current codes, however, the measured longitudinal stiffness designed to limit the displacement of the tests were much smaller in comparison with the longitudinal stiffness on the codes.

• Journal of the Korean Geotechnical Society
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• v.29 no.12
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• pp.35-44
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• 2013

In this study, a particle method without using grid was applied for analysing large deformation problems in soil flows instead of using ordinary finite element or finite difference methods. In the particle method, a continuum equation was discretized by various particle interaction models corresponding to differential operators such as gradient, divergence, and Laplacian. Soil behavior changes from solid to liquid state with increasing water content or external load. The Mohr-Coulomb failure criterion was incorporated into the particle method to analyze such three-dimensional soil behavior. The yielding and hardening behavior of soil before failure was analyzed by treating soil as a viscous liquid. First of all, a sand column test without confining pressure and strength was carried out and then a self-standing clay column test with cohesion was carried out. Large deformation from such column tests due to soil yielding or failure was used for verifying the developed particle method. The developed particle method was able to simulate the three-dimensional plastic deformation of soils due to yielding before failure and calculate the variation of normal and shear stresses both in sand and clay columns.

• Cross-Cultural Studies
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• v.39
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• pp.219-240
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• 2015

The following summarized argument is the comparative research of the characteristics of automatic techniques demonstrated in the mixed expression of foreign language and Korean language in Lee Sang's poetry. Our research examines the use of foreign languages such as French and English shown in Lee Sang's poems, and then, recognized the characteristics of the automatic techniques demonstrated by the parallel marks and signs of Korean language. The automatical technique's element that Lee Sang made use of is a language of loanblend, consisting of free use of French, English, Japanese and Korean. The mathematical and geometric figures such as numbers and shapes can be seen as an important poetic language. In Lee Sang's poetry, the French words "AMOUREUSES" and "ESQUISSE" and English words "I WED A TOY BRIDE" are considered as parts of Korean language. The use of foreign language is seen by the readers as encodes of a unacquainted language and it provides rhetorical characteritstics that gives off profanatory feeling about the poetry. The poet is seen to have created a new poetic language that excess the standards of the limitations that Korean and Chinese marks have through the application of polysems and poliphonyic effects that foreign languages have. The mathematical and geometric signs are Lee Sang's special experimental elements that can't be seen in other literary poetries. They are conversational and the requirements for the expression of abstract artistry and esthetics. The language used in his poetry are external to those traditional poetic languages and they mix freely with other poetic elements to become an automatic technique used in the writing. Lee Sang's techniques can be considered as the pursuit of defiance and departure, freedom about literature and artistry. Moreover, the avant-garde expressionism is the literary form that demonstrated the sense of inferiority, nervousness and loneliness risen from physical pain and the abnormal relationship with women in the poet's personal life. The technique shows the longingness of the the Western culture and literature that lay dormant in the poet's consciousness and it is also the expression of ingenious that created the new guide in the Korean poetic literature, exceeding the European surrealism. Lastly, the automatic technique images that are demonstrated by the mixture of the foreign languages and Korean language are the creations of an innate poetic language and poetic literature that can't be imitated by anyone in Korean literature.