• Elastomers and Composites
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• v.34 no.3
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• pp.199-211
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• 1999

In this work, the effects of the addition of epoxy on the properties of PVC-sol sealants were investigated. PVC-sol was plasticized with dioctyl phthalates(DOP). Two kinds of epoxy resins having different epoxy equivalent weight (E.E.W.) were used. It was found that the properties of the PVC-sol sealants were significantly affected by the contents and types of the added epoxy resins. The viscosity behaviors of the epoxy-modified sealants, in the case of epoxy A addition, the viscosity was decreased with increasing the epoxy contents, but In the case of $CaCO_3$ addition, the viscosity was increased with increasing the $CaCO_3$ contents. The viscosity of epoxy modified sealants aged at $45^{\circ}C$ waterbath was decreased with increasing epoxy contents, since the epoxy acted on the sealants as a stabilizer. The thermal stability of the PVC-sol sealants was slightly improved by adding epoxy. The tensile strength and elongation of sealants modified with epoxy A(two functionalities of epoxy) were increased with increasing the epoxy contents up to a certain epoxy contents but was decreased with further increasing the epoxy contents. In the case of $CaCO_3$ addition, the tensile strength of sealants were decreased with increasing the $CaCO_3$ contents. In view of the electrical properties, such as tan ${\delta}$($0.1{\pm}0.04$) and ${\epsilon}_r$($0.5{\pm}0.04$), it was found that the epoxy modified sealants were as good as insulators.

• 한국전산유체공학회:학술대회논문집
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• 2010.05a
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• pp.147-154
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• 2010

The world is gradually running short of fossil fuel. Currently, the role of wind turbine is attracting great attention from all over the world. The objective of this study is to investigate blades of Vertical-axial wind turbine (VAWT) for optimum design using the CFD from the aerodynamics point of view. Because one of the performance of wind turbine depends on shape of blades, the study of comparing one gyro mill type blade and a modified one was carried out. Using the results of computation, we calculated and compared RPM for both models at same wind velocity. And we calculated angular acceleration and moment of inertia to find torque in every time-step. And the pressure contour and velocity profile around the blade were analyzed Also, this study is performed to calculate the wake effect.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2000.04a
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• pp.141-150
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• 2000

In this study liquefaction hazard potential was assessed by modified Seed and Idriss method and maps of liquefaction hazard potential utilized by LPI(Liquefaction Potential Index) and FE(Equivalent Liquefaction Factor of Safety) were constructed in two dimensional space, Comparisons of liquefaction hazard maps assessed by LPI and FE are represented to verify the FE method proposed in this study. Based on the results of comparing liquefaction hazard map using LPI and FE there is similar distribution trend of zonation indices. from the result of comparison of liquefaction hazard maps of FE base using Hachinohe and ofunato PGA(Peak ground Acceleration) data at one site of port and harbor in Korea the values of FE in liquefaction hazard map using Hachinohe data are underestimated. And in the view of quantitative analysis FE is more convenient than LPI because types of results from FE are factor of safety that widely used in geotechnical practice and aseismic design standard for port and harbor in Korea.

• Proceedings of the Korean Geotechical Society Conference
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• 2003.03a
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• pp.521-528
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• 2003

In this study, a newly modified soil nailing technology called as the NDB(New Down and Board) soil nailing system is introduced. To improve the trafficability, workability, and economical efficiency, SMC(Sheet Molding Compound) board is adopted instead of using the concrete block facing. The SMC board has a distinct advantage of showing a fine view by directly coating with any kind of environmental photos. Composite material properties of the SMC board and cement grout are distinguished features of the NDB soil nailing system. In the present study, both laboratory tests(bending and punching failure tests) and field pull-out tests are carried out to analyze the behavior characteristics of the NDB soil nailing system, including the stress and strain distribution.

• Structural Engineering and Mechanics
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• v.7 no.2
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• pp.203-216
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• 1999

A previously proposed finite element formulation method is refined and modified to generate a new type of elements. The method is based on selecting a set of general solution modes for element formulation. The constant strain modes and higher order modes are selected and the formulation method is designed to ensure that the element will pass the basic single element test, which in turn ensures the passage of the basic patch test. If the element is to pass the higher order patch test also, the element stiffness matrix is in general asymmetric. The element stiffness matrix depends only on a nodal displacement matrix and a nodal force matrix. A symmetric stiffness matrix can be obtained by either modifying the nodal displacement matrix or the nodal force matrix. It is shown that both modifications lead to the same new element, which is demonstrated through numerical examples to be more robust than an assumed stress hybrid element in plane stress application. The method of formulation can also be used to arrive at the conforming displacement and hybrid stress formulations. The convergence of the latter two is explained from the point of view of the proposed method.

• Aerospace Engineering and Technology
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• v.13 no.2
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• pp.60-65
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• 2014

In this paper, numerical integration method using operational matrix of integration is studied. Using the operational matrix of integration, modified fixed point iteration method is introduced in order to solve rapidly an initial value problem for non-linear equation of motion. As an example, an initial value problem for orbital motion is considered. Through the numerical example, it is shown that the algorithm is efficient from the computational time point of view.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.2
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• pp.224-232
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• 2000

Four turbulent $k-{\varepsilon}$ models (i.e., standard model, modified models with streamline curvature modification and/or preferential dissipation modification) are applied in order to analyze the turbulent flow of wall-attaching offset jet. For numerical convergence, this paper develops a method of slowly increasing the convective effect induced by skew-velocity in skew-upwind scheme (hereafter called Partial Skewupwind Scheme). Even though the method was simple, it was efficient in view of convergent speed, computer memory storage, programming, etc. The numerical results of all models show good prediction in first order calculations (i.e., reattachment length, mean velocity, pressure), while they show some deviations in ·second order (i.e., kinetic energy and its dissipation rate). Like the previous results obtained by upwind scheme, the streamline curvature modification results in better prediction, while the preferential dissipation modification does not.

• Journal of environmental and Sanitary engineering
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• v.14 no.1
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• pp.97-102
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• 1999

This study was carried out view that reuse of sludge of adsorbent for benzene in carbonized cast compare with activated carbon. Not only the carbonized cast is good than carbonized carbon in cation exchange capacity and 12 adsorption capacity, but also benzene adsorption capacity is no differences compare to activated carbon. As results, benzene adsorption capacity of carbonized cast and activated carbon are decreased as temperature increase($25~70^{\circ}C$).It is compatible in Lamgmuir model. Therefore, carbonized cast is applied general adsorbent. From experimental results and data regression, in model concerning effect of temperature, relative errors between the experimental data and those calculated by the model are within the range of 1.2~7.8%. In relative humidity effect (RH 0.25~0.50) of benzene adsorption, modified Freundlich model : $QB_{enzene}{;\}QB_{enzene},{\}_{RH=0}=1-kRH^{IN}$, relative errors between the experimental data and those calculated by the model are within are range of 0.5-5.1%. The constants k and l/n in equation were found to be 1.25, 1.89 in carbonized cast.

• The Research Journal of the Costume Culture
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• v.4 no.3
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• pp.407-426
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• 1996

The study, "a semiotic analysis on 1930′s costume", is based on semiotic theory which analyze the meaning of signs. In the novels, "흙" and "삼대", character′s costume were used as a visual language that implies massages of character′s status, class, and the view of value. Analyzing the meaning of clothing signs, clothing could deliver the people′s informations to others and could be first things when people accept new value. The object of the studies are the novels, Hulk(흙) and Samdae(삼대) which are written by lee, Kwang-Soo and Yeom, Sang-Seob. In the novels, the social structure is classed as modern and traditional after we accept the western cultures and institutions. The traditional clothing, Han Bok, were dressed by the conservative woman. However, we could find the modernized woman dress with the western dress and the modified traditional style. According to the result of the research, we could find that clothing could be a sign which indicates value and also clothing is one of the first thing to change when people acquired new value.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.13 no.3
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• pp.168-182
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• 1984

For the purpose of drying high moisture rough rice effectively, from the view point of pre-drying, some basic experiments of fluidized bed drying of rough rice were carried out. The minimum fluidization velocities $(U_{mf})$ for both rough rice and glass bead were analyzed to find out fluidizing characteristics. The main results obtained were as follows ; 1) Minimum fluidization velocity of rough rice and glass bead were 2.01m/s and 4.07m/s, respectively, when using the distributor with $16\%$ opening ratio. 2) $U_{mf}$ calculated by Shirai's empirical equation and that calculated by Wen's modified equation were inconsistent with experimental data, while $U_{mf}$ calculated by Ergun's equation was consistent with the experimental data. 3) The following equations, on the basis of Leva's equation, were obtained. $$C_{mf}=1.19\times10^{-4}(Re_p)^{-0.0318)\;(rough rice)$$ $$C_{mf}=1.02imes10^{-4}(Re_p)^{-0.0047)\;(glass bead)$$