• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1576-1580
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• 2007

Typical lip seals are widely used as sealing mechanism of rotary and reciprocating shaft. Double lip seal has comparatively high stiffness and dynamic radial eccentricity. Usually material of these seals is made of elastomer and nonlinear finite element analysis is required to analyze behaviour of this material because Young's modulus is varied with working load. In this paper, MSC MARC/MENTAT is used for nonlinear analysis of double lip seal with pressure variation and interference. The contact normal force of double lip seal between lip and shaft is analyzed to reduce power loss when shaft rotates.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.2362-2367
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• 2005

This paper reports a technique for discriminating double talk and echo path change using the stochastic characteristics of power change for an adaptive noise canceller. The causes of rapid error increasing are double talk and echo path change. When the echo path is changed, the system corrects the impulse response in order to reduce the error. However, in the case of double talk, the system has to suspend the updating impulse response in order to maintain the quality of the voice signal. In the conventional system, it was difficult to discriminate between the two situations. In this research, the stochastic characteristics of the voice power change in the double talk period were experimentally verified to be different from the power change during echo path changing. Based on the results, a new double talk detection method is proposed.

• Design & Manufacturing
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• v.10 no.2
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• pp.39-43
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• 2016

Most of automobile parts manufactured through sheet metal forming are mass-produced by using press mold. In recent years, automation and speeding up of press lines have been expanding to maximize product productivity using a press die. The proportion of the moving time in the press line is high, and therefore requires high-speed and automated equipment for the moving process. In this paper, to provide the double-moving system can be the moving time reduction and increased productivity. Developed transport system consists of the material supply, the material feeding device and the PLC controller and the devices are positioned between each of the pressing process. In this paper, the double-moving system including developed units using a multi-axial single-acting through this reduced the C/T(cycle time) and improved the productivity.

• Macromolecular Research
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• v.13 no.2
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• pp.156-161
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• 2005

The thermal transitions of a nylon 6/layered silicate nanocomposite were studied by differential scanning calorimetry and in-situ synchrotron X-ray diffraction. The drawn film of the nylon 6/layered silicate nanocomposite typically showed three endotherms in the DSC thermogram; a very broad endotherm at $\sim120^{\circ}C(T_{1})$, a double-melting endotherm at $\sim215^{\circ}C(T_{2})$, and a high temperature endotherm at $\sim240^{\circ}C(T_{3})$. The drawn film of the nylon 6/ layered silicate nanocomposite was comprised of a mixture of the $\alpha and \gamma$ forms, with $the \alpha form$ being generated by drawing the pressed film having $the \gamma form$. The melting and crystallization of the crystals were observed at the above thermal transitions during the heating experiment performed at the Pohang X-ray synchrotron radiation source (4C2). The newly generated form was meta-stable and melted $at {\sim}T_{1}$. The double-melting $at {\sim}T_{2}$ was due to the exothermic crystallization of $the \alpha form$ during the main endothermic melting of $the \gamma form$. $The \alpha form$ crystallized $at {\sim}T_{2}$ and melted $at {\sim}T_{3}$.

• Journal of the Korean Arthroscopy Society
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• v.10 no.1
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• pp.108-111
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• 2006

We present a case of double medial plica that developed on right knee joint. There has been no documented case of double medial plica of the knee joint. In a general way, double medial plica syndrome is very difficult to diagnose because it does rarely develop and symptoms are non-specific or not present. It is difficult to distinguish between pain originating from the medial plica and from other internal derangement of the knee. This patient had symptoms including aggravating right knee pain with sitting position or knee flexion for 3 months. We performed MRI and arthroscopy for more accurate diagnosis. MRI T1, T2 images showed typical double medial plica and we had performed arthroscopic excision of symptomatic medial plica in right knee joint. Arthroscopic resection provided satisfactory relief of symptom.lasting and satisfactory relieve of symptom.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.5
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• pp.229-233
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• 2016

In this paper, we present the four genetic nitrogenous bases of C, U(T), A, G to matrices and describe the structures from $4{\times}4$ RNA(ribose nucleic acid) to $8{\times}8$ DNA((deoxyribose nucleic acid) matrices. we analysis a deoxyribose nucleic acid (DNA) double helix based on the block circulant Hadamard-Jacket matrix (BCHJM). The orthogonal BCHJM is anti-symmetric pair complementary of the core DNA. The block circulant ribonucleic acid (RNA) repair damage reliability is better than the conventional double helix. In case of k=4 and N=1, the reliability of block circulant complementarity is 93.75%, and in case of k=4 and N=4, it is 98.44%. Therefore it improves 4.69% than conventional case of double helix.

• Transactions of Materials Processing
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• v.27 no.1
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• pp.37-47
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• 2018

In this paper, a double spot welding process, utilizing electric resistance heating dies, is suggested for the spot welding of dissimilar metal plates for drawing and concurrent spot welding. This double welding process has two heating methods for the fusion welding at the interfacial zone between steel and aluminum plates, such as heating method by thermal conduction of electric resistance by welding current induced to heating dies, and heating method by electric resistance between contacted surfaces of two plates by welding current induced to copper electrode. This double welding process has welding variables such as each current induced in heating dies and in copper electrode, outer diameters of heating dies, and edge shape of copper electrode. Experiments for current conditions in welding process should be demanded in order to get successful welding strength. It was known that the welding strength could be reached to the value demanded on industry fields under such welding conditions as heating dies of outer ring dia.12mm contacted on steel plate, as heating dies of outer ring dia. 14mm contacted on aluminum plate, and as copper electrode of dia. 6.0mm, and as 3 times continuous heating method by $1^{st}$ current of 11 kA(9cycle), $2^{nd}$ current 11 kA(60cycle), $3^{rd}$ current 7 kA(60cycle) applied in steel heating dies and copper electrodes, flat edge of copper electrode, for double spot welding process of dissimilar metal plates of steel and aluminum of 1.0 mm thickness.

• Journal of Ocean Engineering and Technology
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• v.38 no.4
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• pp.164-173
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• 2024

In this study, a submerged breakwater with effective wave control and eco-friendly characteristics is developed and proposed. Hydraulic experiments are conducted to compare the hydraulic performance of a submerged breakwater and an eco-friendly double-row submerged breakwater. The hydraulic characteristics are analyzed based on wave reflections and the transmission-splitting method for each experimental cross-section. This splitting technique utilizes Goda's two-point method, which employs the spectra of two irregular superposed wave fields. In addition, the reliability of the results obtained from the hydraulic experiments is discussed by comparing the results with empirical formulas. The eco-friendly double-row submerged breakwater features approximately half the width of a typical submerged breakwater. Nevertheless, its transmission coefficient (K_T) is approximately 20% more effective, and the difference in the average reflection coefficient (K_R) values between the two is approximately 0.17. Moreover, the dissipation coefficient (K_D) shows a generally similar trend. Based on these experimental results, the hydraulic performance of the eco-friendly double-row submerged breakwater is more efficient regarding wave control, compared with a typical submerged breakwater. These hydraulic characteristics confirm that the numerical model developed for the eco-friendly double-row submerged breakwater accurately reproduces the K_T, K_R, and K_D values within ±5%.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.387-392
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• 2005

Double-deck train have studied in the next generation train in KRRI. Double-deck train have more seat capacities compared with single deck vehicles and is a efficient, reliable and comfortable alternative train. Because of heavy weight, weight minimization of double-deck train carbody is imperative to reduce cost and extend life-time of train. Weight minimization problem of the double-deck train car-body is required to decide 66 design variables of thicknesses for large aluminum extruded panel while satisfying stress constraints. Design variables are too many and one execution of structural analysis of double-deck train carbody is time-consuming. Therefore, we adopt approximation technique to save computational cost of optimization process. Metamodels such as response surface model (RSM) and kriging model are used to approximate model-based optimization is described. RSM is easy to obtain and expressed explicit function, but this is not suitable for highly nonlinear and large scaled problems. Kriging model employs an interpolation scheme and is developed in the fields of spatial statistics and geostatistics. Target of this design is to find optimum thickness of AEP to minimize weight of doulbe-deck train carbody. In this study, meta model techniques are introduced to carry out weight minimization of a double-deck train car-body.

• Transactions of Materials Processing
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• v.23 no.1
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• pp.35-40
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• 2014

The deformation characteristics of a double round copper pipe and a single round copper pipe under biaxial compression were studied using a horizontal compression die. The change in punch load and in deformation behavior was measured during the experiments using various compressive deformation rates in the range of 10mm/min. ~ 450mm/min. The maximum punch load for both the double round copper pipe and the single round copper pipe decreased with increasing compressive deformation rate. The maximum punch load for the single round copper pipe was twice that of the double round copper pipe. After a 4.0mm stroke, the deformed shape of the single round copper pipe remained rectangular. However the outer tube of double round copper pipe remained rectangular while the inner tube was clover shaped. The stress and strain distributions in the double round copper pipe and the single round copper pipe show clear differences. The results of numerical simulations using Deform-2D are in good agreement with experimental results.