• 대한전자공학회논문지SP
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• 제45권5호
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• pp.79-86
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• 2008

H.264/AVC는 ITU-T와 ISO/IEC 표준화 단체에서 개발한 차세대 국제 영상압축 표준규격으로 이는 H.261, H.263, MPEG-4 등에 비해 더 좋은 압축 효율을 제공한다. 그러나 전체 인트라 모드에 대해 검색이 수행되므로 연산복잡성이 더욱 증가하는 문제와 하드웨어 자원의 낭비가 발생한다. 따라서 본 논문은 두 개의 프로세서 유닛 기반의 병렬 파이프라인 구조로 표준 모델에 비해 연산 복잡 도를 67% 감소시켰고, 부호화 순서를 병렬 파이프라인 구조에 적합하도록 변화시켜 기존 병렬구조에 비해 하드웨어 자원 낭비를 3% 감소시켰다.

• 대한의용생체공학회:의공학회지
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• 제22권6호
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• pp.519-526
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• 2001

At present. about 0.3 million and more THRs (Total Hip Replacement) in a rear are being done worldwide. The increase in mechanical failure with the increase in THR, required more revisions. Revisions compensate mainly the wear of the artificial joint frictional surface and the loosening of the cup and stem. According to recent researches, loosening is mainly due to wear debris UHMWPE (Ultra High Molecular Weight Polyethylene) from frictional surfaces . To overcome the wear problems associated with artificial joint materials , new surface structures with regular Patterns were designed and fabricated The lubrication Properties were examined to evaluate the wear of the frictional surfaces. The surface structure manifested a Pattern of "dents" with a 0.2-1.0 mm of diameter and 0.6-2.0 mm of Pitch. From the friction test of the SUS316L vs UHMWPE using the frictional tester, we found that the lubrication Performance was improved due to of drastically reduced amount of abrasion. There were optimum sizes for the diameter and the pitch of the Pattern. The results demonstrated that the lubrication properties could be improved by Patterning of the frictional surfaces. The surface Patterning was effective in preventing wear of the frictional surfaces, and the life of an artificial joint could be extended with such Patterning.

• 한국구조물진단유지관리공학회 논문집
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• 제18권4호
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• pp.10-21
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• 2014

프리캐스트 방식에 의해 제작이 가능한 격자형 강합성 바닥판의 이음부는 콘크리트 전단키와 고장력볼트 체결로 구성될 수 있으며, 이와같은 이음부 자체에 대한 휨 및 전단성능은 부재요소에 대한 실험을 통해 분석된 바 있다. 본 연구에서는 실제 바닥판 구조시스템에서 이음부에 의한 횡방향 하중전달 거동을 분석하고자, 길이 2.5m 및 폭 1m의 단위 바닥판 모듈 한쌍에 이음부를 설치한 실험체를 제작하고 중심 및 편심가력 휨실험을 하였다. 이음부에 하중이 직접 가해지는 중심재하 조건에서 고장력볼트의 설치개수가 30cm 간격 9개에서 60cm 간격 4개로 줄어 들 경우, 재하단계에 따라 이음부의 회전이 비교적 더 크게 증가하고, 이에 따라 바닥판 횡방향으로의 하중전달 정도가 감소함을 알 수 있었다. 그러나, 한쪽 바닥판의 중심에 집중하중이 가해지는 편심재하 조건의 경우에는 횡방향 하중전달 거동에 큰 차이가 없었다. 하중 재하방법별로 이음부의 거동을 비교한 결과, 집중하중에 대한 바닥판 횡방향으로의 하중분배 및 전달량은 이음부 자체의 성능뿐만 아니라 바닥판 슬래브의 펀칭전단에 의해서도 제한되는 것으로 분석되었다. 또한, 펀칭 전단파괴가 발생할 때까지 이음부의 고장력볼트가 항복하지 않은 점을 고려할 때, 이음부 고장력볼트의 설치개수를 4개에서 9개로 증가시키는 것은 실질적으로 강도 보다는 이음부 및 바닥판의 휨강성 성능 증가에 더 큰 영향을 미치는 것으로 사료된다.

• Computers and Concrete
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• 제21권3호
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• pp.335-344
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• 2018

More and more special-shaped structural systems have been widely used in various industrial and civil buildings in order to satisfy the new structural system and the increasing demand for architectural beauty. With the popularity of the special-shaped structure system, its seismic performance and damage form have also attracted extensive attention. In the current research, an experimental analysis of six groups of (2/3 scale) T-shaped column joints was conducted to investigate the seismic performance of T-shaped column joints. Effects of the beam cross section, transverse stirrup ratio and axial compression ratio on bearing capacity and energy dissipation capacity of column joints were obtained. The crack pattern of T-shaped column joints under low cyclic load was presented and showed a reversed "K" mode. According to the crack configurations, a tensile-shear failure model to determine the shear bearing capacity and crack propagation mechanisms is developed.

• 한국멀티미디어학회논문지
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• 제25권6호
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• pp.783-792
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• 2022

Versatile Video Coding (VVC) is the latest video coding standard, which had been developed by the Joint Video Experts Team (JVET) of ITU-T Video Coding Experts Group (VCEG) and ISO/IEC Moving Picture Experts Group (MPEG) in 2020. Although VVC can provide powerful coding performance, it requires tremendous computational complexity to determine the optimal block structures during the encoding process. In this paper, we propose a fast ternary tree decision method using two neural networks with 7 nodes as input vector based on the multi-layer perceptron structure, names STH-NN and STV-NN. As a training result of neural network, the STH-NN and STV-NN achieved accuracies of 85% and 91%, respectively. Experimental results show that the proposed method reduces the encoding complexity up to 25% with unnoticeable coding loss compared to the VVC test model (VTM).

• 한국경영과학회지
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• 제20권3호
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• pp.105-122
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• 1995

Based on linear models, the inference about the true measurement x$_{f}$ and the optimal designs x (nx1) for the calibration experiments are considered via Baysian statistical decision analysis. The posterior distribution of x$_{f}$ given the observation y$_{f}$ (qxl) and the calibration experiment is obtained with normal priors for x$_{f}$ and for themodel parameters (.alpha., .betha.). This posterior distribution is not in the form of any known distributions, which leads to the use of a numerical integration or an approximation for the calculation of the overall expected loss. The general structure of the expected loss function is characterized in the form of a conjecture. A near-optimal design is obtained through the approximation nof the conditional covariance matrix of the joint distribution of (x$_{f}$ , y$_{f}$ $^{T}$ )$^{T}$ . Numerical results for the univariate case are given to demonstrate the conjecture and to evaluate the approximation.n.

• 한국안전학회지
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• 제16권3호
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• pp.19-25
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• 2001

The friction-welding SM25C is a substitute for the suing steel that is utilized in the machinery, airplane, and automobile, ok. This substitution would provide reduction of material and weight of welding parts. From the result we found that the strength of the friction welded joint was 529-617MPa and the toughness 1.2 times higher than that of the base metal. The optimal condition of friction welding was found as follows : n=2000rpm, $P_1$=68㎫, $P_2$=137MPa, $t_2$=2sec, $t_1$=2-4sec, Considering the strength, the hardness, and the reduction of area in the friction welding, the fiction welding using SUP9A and SM25C was found to cause no problem in on-the-job application.

• 한국전기전자재료학회논문지
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• 제32권1호
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• pp.30-34
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• 2019

A newly proposed T-shape piezoelectric actuator, composed of piezoelectric benders, was designed and studied. This actuator has four legs, and can walk in both forward and backward directions. The piezoelectric actuator has a simple structure and can be easily fabricated. It consists of a piezoelectric bender and a joint. The piezoelectric bender is composed of carbon and ceramic materials. Therefore, there is an advantage in that it can be fabricated on a very small scale. Elliptical displacements of the piezoelectric actuators were analyzed by finite element analysis. Elliptical motion at the tip occurred at two voltages having a 90-degree phase difference. Based on the finite element analysis results, prototype actuators with maximum displacements were fabricated, and the characteristics of their movements were characterized.

• 콘크리트학회지
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• 제9권2호
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• pp.167-177
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• 1997

모멘트 연성골조의 접합부와 기둥은 적절한 에너지흡수 능력과 구조물의 횡붕괴를 방지하기 위하여 탄성적으로 거동해야 하며, "강한 기둥-약한 보"의 설계개념을 채택하고 있다. 접합부는 골조구조의 취약부분으로 인정되고 있지만 부재설계에서는 접합부를 구성하는 보와 기둥에 의해서 접합부의 치수가 결정되기 때문에 접합부가 부담해야 하는 하중조건과 보강방법을 결정하는데에 어려움이 있다. 또한 콘크리트의 고강도화, 경량화에 의해 부재단면은 작아지게 되고 상대적으로 철근량은 늘어나게 되므로 접합부 영역의 응력부담은 이전보다 훨씬 높아지게 되었다. 따라서 접합부의 적절한 구조성능 확보 및 시공상의 문제점을 개선하기 위하여 접합부의 설계 및 상세에 특별한 주의가 필요하다고 할 수 있다. 이에 본 연구에서는 슬래브의 기여도를 고려한 접합부의 적절한 보강방법을 제시하기 위한 기초자료로서 $\frac{2}{3}$의 실물크기로 4개의 고강도 콘크리트 보-기둥 접합부를 제작하고, 반복하중 실험을 수행하였다.실험을 수행하였다.

• 대한치과보철학회지
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• 제31권2호
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• pp.249-270
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• 1993

For understanding of anatomy, physiology, and diseases of human TMJ, it is required to evaluate quantitatively the movement of the disc and condyle head of mandible. The histologic section of cadaver TMJ were examined, and the magnification of the MR image and its details of anatomy were evaluated. And then a quantitative analytic method, by comparing the Sectograph and the MR image of vital human TMJ, was proposed. For this study, 15 subjects(Male, 24~35years) were selected from a prosthodontic examination randomly, and each subject’s five interocclusal rubber registration records were made on the ICP, and 5, 10, 15, and 20mmjaw opening positions. All subjects were radiographed with a Denar Quint Sectograph Image System(Denar Corp., USA), and imaged with a MRP-20EX MR Image System(0.2T, Permanent Magnet Type, Hitachi Medical Corp., Japan) using an 100mm diameter bilateral type surface coil. These images were traced on the acetate tracing paper, and analyzed In this study, the findings led to the following conclusions. 1. In comparison of the histologic section of autopsy specimen with the MR image at the same section, the size(dimension) of MR image was 70% of the real one. It was possible to recognize the shape of articular disc, anterior and posterior attachments, and adjacent soft tissues, because of the excellent reproducibility of anatomical structure. 2. When we compared the amount of joint space on MR image with that of joint space on sectograph, the amount of joint space on sectograph was significantly greater than that of joint space on MR image, except at the top of condylar head. 3. The position of minimum joint space on sectograph at intercuspal position didn't coincide with the middle position of articular disc on MR image, and was approximately in the anterior third of posterior band of articular disc. 4. The amount of condylar movement on MR image at opening movement was greater than that of articular disc movement. From Intercuspal position to 5mm jaw-opening movement, the condylar movement showed hinge one, and over the range 5mm jaw-opening it suggested hinge & translatory one. 5. In terms of area variation of articular disc measured on MR image in sagittal plane, the area of posterior band increased with increasing the amount of Jaw opening, but the area of anterior band decreased conversely.