• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.3
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• pp.439-452
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• 1994

A method to optimize the cost of R/C frames and an algorithm of the optimal limit state design for R/C frames subjected to dynamic loads are presented. The modal superposition method was used to find the dynamic responses of the frames. Each member of R/C frame is made up of more than two elements and the stiffness matrix and consistent mass matrix of three d.o.f in the node of each element was used to include axial, shear and flexural effects. The objective function to be minimized formulated the cost of materials, steel and concrete, and optimised to satisfy the behaviors of R/C frame and each constraint imposed by the limit state requirements. Both objective function and each constraint are derived in terms of design variables which include the effective depth, beam width, compression and tension steel area, and column shear steel area. A few applications are presented which demonstrate the feasibility, the validity and efficiency of the algorithm for automated optimum design of R/C frames where dynamic behavior is to be considered.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.51 no.7
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• pp.308-316
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• 2002

In this paper, we propose a robust digital copyright-protection technique based on the concept of human auditory system. First, we propose a watermarking technique that accepts the various attacks such as, time scaling, pitch shift, add noise and a lot of lossy compression such as MP3, AAC WMA. Second, we implement audio PD(portable device) for copyright protection using proposed method. The proposed watermarking technique is developed using digital filtering technique. Being designed according to critical band of HAS(human auditory system), the digital filers embed watermark without nearly affecting audio quality. Before processing of digital filtering, wavelet transform decomposes the input audio signal into several signals that are composed of specific frequencies. Then, we embed watermark in the decomposed signal (0kHz~11kHz) by designed band-stop digital filer. Watermarking detection algorithm is implemented on audio PD(portable device). Proposed watermarking technology embeds 2bits information per 15 seconds. If PD detects watermark '11', which means illegal song. PD displays "Illegal Song" message on LCD, skips the song and plays the next song, The implemented detection algorithm in PD requires 19 MHz computational power, 7.9kBytes ROM and 10kBytes RAM. The suggested technique satisfies SDMI(secure digital music initiative) requirements of platform3 based on ARM9E core.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.11
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• pp.223-229
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• 2016

In this study, a cold forging process was developed for the roller tappet housing of an engine valvetrain system. A tappet sample was manufactured and subjected to an endurance test. The material properties were obtained from a compression test, and forging analysis was carried out to design a forging process using a commercial program, Deform-3D. The forging process was set up based on the analysis results, and a die set and sample tappet housing were manufactured. To evaluate the sample, the dimensional accuracy, surface roughness, parallelism, and concentricity were measured and confirmed. To evaluate the actuation and durability, a special test rig was developed to simulate the valvetrain system of the engine. An actuation test was performed based on the idle speed of a general diesel engine, and an endurance test was done based on the maximum speed. The results show minor wear of 0.002 mm. The developed test rig will be used to evaluate the actuation and durability of other valvetrain parts.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.12B
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• pp.2391-2400
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• 1999

Vector quantizer (VQ) is an efficient data compression technique for low bit rate applications. However, the major disadvantage of VQ is its encoding complexity which increases dramatically as the vector dimension and bit rate increase. Even though one can use a modified VQ to reduce the encoding complexity, it is nearly impossible to implement such a VQ at a high bit rate or for a large vector dimension because of the enormously large memory requirement for the codebook and the very large training sequence (TS) size. To overcome this difficulty, in this paper we propose a novel structurally constrained VQ for the high bit rate and the large vector dimension cases in order to obtain VQ-level performance. Furthermore, this VQ can be extended to the low bit rate applications. The proposed quantization scheme has a form of feed-forward adaptive quantizer with a short adaptation period. Hence, we call this quantization scheme sample-adaptive product quantizer (SAPQ). SAPQ can provide a 2 ~3dB improvement over the Lloyd-Max scalar quantizers.

• Journal of the Korean Geotechnical Society
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• v.20 no.8
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• pp.59-66
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• 2004

In this study, the behavior characteristics of vertical and batter piles were analyzed by the model tests and the numerical analyses. Model steel pipe piles with the inclination of 0$^{\circ}$, 10$^{\circ}$, 20$^{\circ}$ and 30$^{\circ}$ were driven into sands with the relative density of 79%. The static compression load tests and numerical analyses using PENTAGON 3D were performed. The bearing capacities of batter piles with inclination of 10$^{\circ}$, 20$^{\circ}$ and 30$^{\circ}$ were 111, 95, and 81% of those of vertical pile in model tests, and the results of numerical analyses were similar to those of model tests. The bearing capacities p.oposed by Petrasovits and Award (1968) were similar to those of model test in the inclination of 10$^{\circ}$, but overestimated in the inclination of 20$^{\circ}$ and 30$^{\circ}$. The skin frictions and end bearing loads were the maximum in the inclination of 10$^{\circ}$ and decreased with increasing the inclination angle.

• Journal of Korea Multimedia Society
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• v.15 no.9
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• pp.1093-1101
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• 2012

Multi-view video is obtained by capturing one three-dimensional scene with many cameras at different positions. Multi-view video coding exploits inter-view correlations among pictures of neighboring views and temporal correlations among pictures of the same view. Multi-view video coding which uses many cameras requires a method to reduce the computational complexity. In this paper, we proposed an efficient prediction structure to improve performance of multi-view video coding. The proposed prediction structure exploits an average distance between the current picture and its reference pictures. The proposed prediction structure divides every GOP into several small groups to decide the maximum index of hierarchical B layer and the number of pictures of each B layer. Experimental results show that the proposed prediction structure shows good performance in image quality and bit-rates. When compared to the performance of hierarchical B pictures of Fraunhofer-HHI, the proposed prediction structure achieved 0.07~0.13 (dB) of PSNR gain and was down by 6.5(Kbps) in bitrate.

• Journal of the Korean Geosynthetics Society
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• v.15 no.4
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• pp.33-42
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• 2016

Discrete Element Method was conducted for rock and coarse-grained materials in development of granular mechanics and related numerical model due to analyze and apply micromechanical property. And it was verified that the analysis to consider bonding effect was insufficient. In this study, to overcome limits of existing method, it was conducted to analyze difference between indoor test result and bonding effect using $PFC^{3D)}$. For indoor test of mixed soil, uniaxial compression tests by curing time and by cement content were performed. And, DEM to suitable for each condition of indoor test was conducted. In the result of this study, in terms of geotechnics, it was verified that DEM can be used for application as numerical laboratory as well as prediction of micro and macro behavior about bonding effect of mixed soil.

• Journal of Broadcast Engineering
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• v.13 no.5
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• pp.586-595
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• 2008

In this paper, we propose an adaptive multi-view video service framework suitable for mobile environments. The proposed framework generates intermediate views in near-realtime and overcomes the limitations of mobile services by adapting the multi-view video according to the processing capability of a mobile device as well as the user characteristics of a client. By implementing the most of adaptation processes at the server side, the load on a client can be reduced. H.264/AVC is adopted as a compression scheme. The framework could provide an interactive service with efficient video service to a mobile client. For this, we present a multi-view video DIA (Digital Item Adaptation) that adapts the multi-view video according to the MPEG-21 DIA multimedia framework. Experimental results show that our proposed system can support a frame rate of 13 fps for 320{\times}240 video and reduce the time of generating an intermediate view by 20 % compared with a conventional 3D projection method.

• Advances in pediatric surgery
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• v.3 no.1
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• pp.71-76
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• 1997

A 3-year-old boy with a Wilms' tumor had unusually severe hypertension, polydipsia, polyuria and hypokalemia. Physical examination on admission was unremarkable except for the presence of a smooth, firm mass in the right abdomen. Computerized tomography showed a tumor occupying the upper two thirds of the right kidney. Plasma renin activity and aldosterone concentration were markedly elevated, 37.7 mg/ml/hour(normal in supine position 0.15-2.33 mg/ml/hour) and 120.1 ng/dL(normal in supine position 1 to 16 ng/dL), respectively. Hypertension varied from 150/90 mmHg to 240/180 mmHg, and was not effectively controlled by antihypertensive drugs. Right nephrectomy was performed on the sixth hospital day. At laparatomy, there was no evidence of mechenical compression of the renal artery by the tumor. The tumor, about 8 cm in diameter, was confined to the renal capsule without involvement of the renal blood vessels at the hilum. Histopathology was Wilms' tumor of favorable histology. On electron microscopy, tumor cells contained intracytoplasmic electron dense secreting graules, suggesting the possibility of renin secreting tumor cells. Shortly after nephrectomy, signs and symptoms were relieved dramatically, and plasma renin activity and aldosterone concentration were also decreased to normal.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.6C
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• pp.497-504
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• 2005

We propose an efficient video watermarking scheme using re-estimation and minimum modification technique of motion vectors. Conventional methods based on motion vectors do watermarking using modification of motion vectors. However, change of motion vectors results in the degradation of video quality. Thus, our scheme minimizes the modification of the original motion vectors and replaces an original motion vector by the adjacent optimal motion vector using re-estimation of motion vectors to avoid degradation of video quality. Besides, our scheme guarantees the amount of embedded watermark data using the adaptive threshold considering for an efficient video watermarking. In addition, this is compatible with current video compression standards without changing the bitstream. Experimental result shows that the proposed scheme obtains better video quality than other previous algorithms by about $0.6{\sim}1.3\;dB$.