• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.5
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• pp.650-658
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• 1997

Analysis and control of intake charge motion such as swirl and tumble are very important factors in improving the gasoline engine performance. In this paper, single-frame PTV (particle tracking velocimetry) is used to investigate intake tumble patterns in a steady flow test rig of gasoline engine with dual-intake-valve and pent-roof combustion chamber. Intake tumble pattern is quantified in accordance with blockage ratio of TIV (tumble intensifying valve) with single- frame PTv.The view of the instantaneous 2-D velocity field gives a realistic understanding of in-cylinder flow field. Thus it is confirmed that PTV is a effective tool in engine design. In conventional port, two tumble structures appear clearly, and the larger one is observed under the exhaust valve side and the smaller is right below the intake valve side. The larger vorticity is observed in TIV port, thus it is concluded that TIV have an effect on intensified tumble motion in cylinder flow.

• ETRI Journal
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• v.37 no.5
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• pp.940-944
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• 2015

We present a frame synchronization algorithm for lowdensity parity-check (LDPC) coded burst transmissions, which combines a conventional pilots-assisted frame synchronization algorithm and a code-aided algorithm based on the mean magnitude of the soft outputs from the LDPC decoder. With moderate computational complexity, the proposed algorithm is more efficient in bandwidth than conventional pilots-assisted algorithms. When compared with other code-aided algorithms, the proposed algorithm offers a better trade-off between complexity and performance. Simulation results in the case of an 8-PSK system with (1944, 972) LDPC code show that the proposed algorithm can achieve a performance equivalent to that of the perfect frame synchronization, with a bandwidth efficiency loss of 0.06 dB due to the use of pilot symbols.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.1008-1011
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• 2005

It is necessary for the design of lead frame punches in blanking to consider buckling because inner lead pitch of lead frame has been narrowed by miniaturization and high accumulation of semiconductor. In addition, if process variables change in press stamping process, the lift of punches is no longer influenced in wear and punches can be broken suddenly. To prevent the fracture of fine pitch lead frame punches, having considered applying reinforcement to it, this paper verified the design with buckling analysis. This study presents the optimal position and number of reinforcement to be attached to punches. Finally this study presents design rules of attaching reinforcement.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.29 no.1
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• pp.85-93
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• 2016

In this study, finite element analyses of masonry infilled frames using a general purpose FE program, ABAQUS, were conducted. Analysis models consisted of the bare frame, infilled frames with masonry wall thickness of 0.5B and 1.0B, respectively. The masonry walls were constructed using the concrete bricks which were generally used in Korea as infilled wall. The material properties of frames and masonry for the analysis were obtained from material tests. However, four times increased the tensile strength was used for 1.0B wall, which is seemingly due to the differences in locating the bricks. The force-displacement relation and development of crack from the FE analysis were very similar to those from the experiments. From the FEA results, contact force between the frame and masonry, distribution of shear force and bending moments in frame members were analyzed. Obtained contact stress shows a trianglur distribution, and the contact length for 0.5B speciment and 1.0B specimen were close to the value estimated using ASCE 41-06 equation and ASCE 41-13 equation, respectively. Obtained shear force and bending moment distribution seems to replicate actual behavior which originates from the contact stress and gap between the frame and masonry.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.1
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• pp.54-60
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• 2001

This study is to investigate the mechanical properties and the fatigue crack propagation of fire resistance steel for frame structure as the chemical composition was changed by addition of N, B and rolled end temperature was varied. We used two kinds of specimen, the one is parallel and the other is perpendicular to the rolling directions. As rolled end temperature increased, volume fraction of ferrite and pearlite decreased, but volume fraction of baintie and grain size increased. Micro-hardness decreased as rolled end temperature increased, but tensile and yield strength increased. Volume fraction of ferrite and pearlite decreased by addition of N. But volume fraction of bainite, tensile and yield strength increased. Microstructure was changed to martensite by addition of B, and tensile and yield strength increased. Fatigue life of TL direction specimen was shorter than that of LT direction specimen. There was no significant effect to fatigue crack propagation rate by addition of N and changing rolling condition, but fatigue life was increased by addition of B.

• Transactions of Materials Processing
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• v.13 no.8
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• pp.689-695
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• 2004

This paper is concerned with the analysis of the forming load characteristics of a forward-backward can extrusion process. The analysis in this paper is extended to the selection of press frame capacity for producing efficiently final product at low cost. The possible extrusion processes to shape a forward-backward can part with different outer diameters are categorized to investigate quantitatively the forming load, forming energy and maximum pressure exerted on the die-material interface. The categorized processes are composed of combined and/or some basic extrusion processes. After the analysis of the forming load characteristics, the frame capacity of press suitable for a selected process could be determined along with securing the load capacity and with considering productivity. In addition, it is also suggested that different load capacities be selected for different dimensions of a part such as the wall thickness in forward direction. The work in this paper could be a good reference for analysis of complex extrusion and selection of proper frame capacity of press to achieve low production cost and thus high productivity.

• Journal of Korean Society of Steel Construction
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• v.21 no.6
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• pp.627-636
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• 2009

The purpose of this study was to evaluate the validity of the second-order analysis using the load amplification factor suggested by design codes. For this purpose, the first-order analysis with the B1 and B2 factors suggested by KBC 2005 and the direct analysis with the load amplification factor suggested by KBC 2009 (draft) were performed for three-story -one-bay and five-story-three-bay unbraced steel frames. The results of the analyses were compared with the results of the second-order inelastic analysis to evaluate the validity of the suggested methods. The main parameters of the analysis were the scale of the frame, the axial load ratio of the column, and the methods of analysis. The research results showedthat the method suggested by KBC 2005 does not properly consider the second-order effect under the high axial load ratio, but the direct analysis method suggested by KBC 2009 (draft) properly estimates the second-order effect without any serious problem.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.46 no.4
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• pp.58-66
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• 2009

Recently the emerging demands of the light-video encoder promotes lots of research efforts on DVC (Distributed Video Coding). As an appropriate video compression method, DVC has been studied, and Wyner-Ziv (WZ) video compression is its one representative structure. The WZ encoder splits the image into two kinds of frames, one is key frame which is compressed by conventional intra coding, and the other is WZ frame which is encoded by WZ coding. The WZ decoder decodes the key frame first, and estimates the WZ frame using temporal correlation between key frames. Estimated WZ frame (Side Information) cannot be the same as the original WZ frame due to the absence of the WZ frame information at decoder. As a result, the difference between the estimated and original WZ frames are regarded as virtual channel noise. The WZ frame is reconstructed by removing noise in side information. Therefore precise noise estimation produces good performance gain in WZ video compression by improving error correcting capability by channel code. But noise cannot be estimated precisely at WZ decoder unless there is good WZ frame information, and generally it is estimated from the difference of corresponding key frames. Also the estimated noise is limited by comparing with frame level noise to reduce the uncertainty of the estimation method. However these methods cannot provide good noise estimation for every frame or each bit plane. In this paper, we propose a noise nodel selection method which chooses a better noise model for each bit plane after generating candidate noise models. Experimental result shows PSNR gain up to 0.8 dB.

• Membrane Journal
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• v.10 no.3
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• pp.155-162
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• 2000

The reverse osmosis membrane housing(HY) was developed for excellent distribution of a feed solution, and the separation performance was compared with the commercialized Rochem(RC) system. The permeation flux of HY system was a little lower than that of RC system. On the other hand, the NaCl rejection ra4io was generally higher. Also, the permeation flux and rejection ratio for type A, B and C modules(disc plate and frame type) were measured using NaCl, sucrose and butanol solutions. The separation performance of type C module for NaCL and sucrose solutions was the most effective, and then those of type A and B were followed, respectively. However, the separation performance for butanol solution was type B, C and A order. The flux improvement ratio of type B to A increased as butanol concentration decreased or operating pressure increased up to 28 bar.

• Journal of the Korea Concrete Institute
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• v.17 no.5 s.89
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• pp.673-678
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• 2005

ACI 318 (1999) defines three types of moment frames: Ordinary Moment Resisting Concrete Frame (OMRCF), Intermediate Moment Resisting Concrete Frame (IMRCF), and Special Moment Resisting Concrete Frame (SMRCF). OMRCF is the most popular type of moment frame in mild seismic zones that requires the least detail and design requirements. This study focuses on the seismic performance of Ordinary Moment Resisting Concrete Frames (OMRCF) designed only for gravity loads. For this purpose a 3-story OMRCF was designed in compliance with the minimum design requirements in ACI 318 (1999). An one third 3 story specimen was made and tested. For scaled model, the similitude law of true replica was applied. The specimen was loaded with quasi-static reversed cyclic lateral loading. The overall behavior of OMRCF is quite stable without abrupt strength degradation. It is found that tested frame has the base shear strength larger than the design base shear for seismic zone 1, 2A and 2B calculated using UBC 1997.