• Geomechanics and Engineering
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• 제13권3호
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• pp.505-515
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• 2017

Based on the collapse characteristics of a shallow rectangular cavity, a three-dimensional failure mechanism which can be used to study the collapsing region of the rock mass above a shallow cavity roof is constructed. Considering the effects of surcharge pressure and surface bolt on the collapsing block, the external rate of works produced by surcharge pressure and surface bolt are included in the energy dissipation calculation. Using variational approach, an analytic expression of surface equation for the collapsing block, which can be used to study the collapsing region of the rock mass above a shallow cavity roof, is derived in the framework of upper bound theorem. Based on the analytic expression of surface equation, the shape of the collapsing block for shallow cavity is drawn. Moreover, the changing law of the collapsing region for different parameters indicates that the collapsing region of rock mass decreases with the increase of the density of surface bolt. This conclusion can provide reference for practicing geotechnical engineers to achieve an optimal design of supporting structure for a shallow cavity.

• Nuclear Engineering and Technology
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• 제55권4호
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• pp.1365-1381
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• 2023

In this paper, a procedure for evaluating the structural integrity of the PCSG (Printed Circuit Steam Generator) unit block is presented with a simplified FE (finite element) analysis technique by applying the homogenization method. The homogenization method converts an inhomogeneous elastic body into a homogeneous elastic body with same mechanical behaviour. This method is effective when the inhomogeneous elastic body has repetitive microstructures, and thus the method was applied to the sheet assembly among the PCSG unit block components. From the method, the homogenized equivalent elastic constants of the sheet assembly were derived. The validity of the determined material properties was verified by comparing the mechanical behaviour with the reference model. Thermo-mechanical analysis was then performed to evaluate the structural integrity of the PCSG unit block, and it was found that the contact region between the steam header and the sheet assembly is a critical point where large bending stress occurs due to the temperature difference.

• 전자공학회논문지
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• 제51권1호
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• pp.107-115
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• 2014

영상의 저 비트 변환 기반의 비트 플레인 정합방법(Bit-Plane Matching : BPM)은 기존의 블록 정합 방법들과 비교해 계산량을 줄이고 간단한 하드웨어 구조 설계를 통해 블록 정합 결과를 획득할 수 있지만, 블록 정합의 정확도가 비교적 낮은 문제점을 가지고 있다. 본 논문에서는 기존의 BPM방법들과 비교해 블록 정합의 정확도를 증가시키면서 동시에 논리 연산으로 정합 결과를 계산할 수 있는 저 비트 변환 기반의 절대 오차합(Reduced-bit transform based Sum of Absolute Difference : R-SAD)을 이용한 블록 정합 알고리즘을 제안한다. 이 방법은 현재 영상과 참조영상을 각각 2-bit의 영상으로 변환하고, 2-bit의 4레벨에 대한 입출력 관계를 이용하여 진리표를 획득한다. 진리표는 Karnaugh map을 통해 간소화 되어 논리 연산으로 절대 오차를 계산할 수 있다. 제안된 방법의 성능 평가를 위한 움직임 보상(Motion Compensation) 실험에서, R-SAD는 기존의 블록 정합 방법들과 비교해 높은 정확도의 정합결과를 획득할 수 있었다.

• 자원환경지질
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• 제18권1호
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• pp.23-39
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• 1985

The northeastern part of Ogcheon zone which consisted mainly of Cambro-Ordovician arenaceous, argillaceous and calcareous formations and Carboni-Triassic arenaceous and argillaceous formations is delineated as the eastern mass of a thrust fault along Choongju-Moongyong-Cheongsan in the middle of the zone. The present study proposes a geotectonic line, Imgye-Samchog fault(see, figure 1) which divides the northeastern part into two blocks, Hambacksan block in the west and East coast block in the east. The igneous rocks in the Hambacksan block ranging from granite to gabbro are distributed in a symmetrical zones parallel to general direction of Ogcheon zone as follows (Fig. 2 and Table 2). Southeast igneous rock zone: it aligns Jurassic granites in its south and Precambrian leucocratic granites in its north. Central igneous rock zone: it aligns Cretaceous granites in its south and Jurassic granites, and some of diorite and gabbro in its north. Northwest igneous rock zone: aligns Jurassic granites in its south and huge batholithic granodiorite in its north. The distribution of the igneous rocks in the East coast block shows an entirely different features from those of Hanbacksan block. In the southern part of the block they assemble in a narrow area ranging in age from Early Proterozoic, through Middle to Late Proterozoic, Devonian, Jurassic, Cretaceous to Tertiary, whereas, the igneous rocks in the northern part of the block gathered to a restricted area, in ages of Middle Proterozoic and Cretaceous. The assemblage of the igneous rocks in the studied area shows a compositionally restricted, mixed S-type and I-type granites, $^{87}Sr/^{86}Sr$ > 0.706, rare volcanics and shortening with upright folding. These lithologic and structural features suggest that the igneous activity in this part related intimately to Hercynotype Orogeny of Pitcher(1979). Chronological episodes of igneous activity from Early Proterozoic to Early Tertiary in the northeastern part are figured.

• 한국정보과학회논문지:컴퓨팅의 실제 및 레터
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• 제15권12호
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• pp.918-922
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• 2009

본 논문에서는 참조 패턴에 따라 페이지 사상 정책과 블록 사상 정책을 선택적으로 사용하는 Janus-FTL을 제안한다. 일반적으로 플래시 메모리의 특성에 따르면, 순차 참조의 경우 블록 사상 FTL이 적당하고, 비 순차적인 참조의 경우 페이지 사상 FTL이 적당하다. 따라서 실용적인 FTL은 데이터의 특성에 따라 플래시 메모리 블록을 블록 사상 또는 페이지 사상 정책으로 선택적으로 사용하면서, 블록 사상 영역과 페이지 사상 영역의 크기를 참조 패턴에 따라 효율적으로 변화하여 할당하는 관리 기법이 필요하다. 본 논문에서는 저장된 데이터가 블록 사상 영역에서 페이지 사상 영역으로 이동하는 퓨전(Fusion) 연산과 반대로 이동하는 디퓨전(Defusion) 연산을 통해, 블록 사상과 페이지 사상 기법을 동시에 활용하는 Janus-FTL을 설명한다. 또한 Janus-FTL을 구현하여 성능을 측정하였으면, 성능 측정 결과에 따르면 기존의 FTL에 비해 최대 50%의 우수한 성능을 보였다.

• 한국멀티미디어학회논문지
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• 제11권7호
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• pp.956-965
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• 2008

H.264는 가장 최근에 제정된 동영상 압축 표준으로 다양한 기법 등을 도입하여 기존의 표준들에 비해 동일한 화질을 유지하면서도 높은 압축 효율을 보여준다. 하지만 이러한 기법들은 처리과정이 복잡해, 계산 과정을 간소화시킨 효율적인 기법들이 요구된다. 따라서 본 논문에서는 새롭게 도입된 기법 중에서 복잡한 처리가 요구되는 인트라 예측의 효율적인 처리를 위한 2단계의 빠른 인트라 예측 방법을 제안한다. 1단계에서는 매크로블록 내 작은 블록들($4{\times}4,\;8{\times}8,\;12{\times}12$ 크기)의 경계 부분의 화소 변화량을 조사하고, 이를 통해서 매크로블록의 평탄 여부를 판단하여 인트라 예측을 위한 블록 크기를 빠르게 선택한다. 2단계에서는 매크로 블록 내부의 대표성을 띄는 화소들을 이용하여 1단계에서 선택된 블록 크기의 여러 모드 중에서 최종 모드를 빠르게 결정한다. 제안한 인트라 예측 기법의 성능측정을 위해 다양한 테스트 동영상으로 화질, 비트율 및 처리시간을 확인한 결과, 관련기법 및 표준과 비교해서 동일한 화질과 비트율을 유지하면서 표준과 비교하여 41.5%, 관련기법과 비교하여 24.7%의 인트라 예측 처리 시간을 감소시켰다.

• Advances in concrete construction
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• 제5권5호
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• pp.451-468
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• 2017

The problem of reducing the self-weight of reinforced concrete structures is very important issue. There are two approaches which may be used to reduced member weight. The first is tackled through reducing the cross sectional area by using voids and the second through using light weight materials. Reducing the weight of slabs is very important as it constitutes the effective portion of dead loads in the structural building. Eleven slab specimens was casted in this research. The slabs are made one way though using two simple supports. The tested specimens comprised three reference solid slabs and eight styropor block slabs having (23% and 29%) reduction in weight. The voids in slabs were made using styropor at the ineffective concrete zones in resisting the tensile stresses. All slab specimens have the dimensions ($1100{\times}600{\times}120mm$) except one solid specimens has depth 85 mm (to give reduction in weight of 29% which is equal to the styropor block slab reduction). Two loading positions or cases (A and B) (as two-line monotonic loads) with shear span to effective depth ratio of (a/d=3, 2) respectively, were used to trace the structural behavior of styropor block slab. The best results are obtained for styropor block slab strengthened by minimum shear reinforcement with weight reduction of (29%). The increase in the strength capacity was (8.6% and 5.7%) compared to the solid slabs under loading cases A and B respectively. Despite the appearance of cracks in styropor block slab with loads lesser than those in the solid slab, the development and width of cracks in styropor block slab is significantly restricted as a result of presence a mesh of reinforcement in upper concrete portion.

• 센서학회지
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• 제22권6호
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• pp.404-409
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• 2013

We devised calibration procedure for industrial thermometers by a comparison method at the boiling point of nitrogen (${\sim}-196^{\circ}C$). The uncertainty of the calibration was 4 mK (k = 2). As experimentally demonstrated in this work, the effect of the atmospheric pressure on the boiling point of nitrogen can be easily detected by the thermometer. Therefore, when the boiling point of nitrogen is used for calibration of thermometer by comparison, either a reference thermometer must be used to provide the reference temperature or the effect of atmospheric pressure should be carefully considered. The use of a copper block with a large thermal mass soaked into the liquid nitrogen was proven to be more reliable, and the stability of the temperature immersed into the copper block was 1.4 mK. The temperatures at the thermometer wells, evaluated by the crossed-measurement method to compensate for the inaccuracy of the thermometers and the linear drift of the temperature of the copper block, were equivalent within 0.23 mK of standard uncertainty.

• Clinical Pain
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• 제19권2호
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• pp.90-96
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• 2020

Objective: To investigate the diagnostic accuracy of two physical examinations (straight leg raise [SLR] and Bragard test) and electromyography (EMG) in patients with lumbosacral monoradiculopathy in acute and chronic state on confirmation of different diagnostic criteria (MRI vs MRI and diagnostic selective nerve root block [DSNRB]). Method: We identified 297 participants retrospectively from the departmental database. MRI evidence of L5 or S1 nerve root compression and a positive result in diagnostic SNRB served as reference standards. They were divided into two groups by the symptom duration: lasting more than 12 weeks in the chronic group and less than 12 weeks in the acute group. The diagnostic value of clinical tests and EMG were compared. Results: The clinical tests (SLR and Bragard test) done in acute stage on detection by MRI and DSNRB had the highest sensitivity (68%) compared to the chronic stage (63%), but sensitivity was low (57%) on confirmation of MRI alone. However, there was no significant difference on sensitivity and specificity of EMG regardless of reference standards and symptom duration. Electromyography was a significant predictor of neuropathic abnormalities on both acute (OR, 6.3; 95% CI, 2.4 to 16.7; p<0.01) and chronic (OR, 6.8; 95% CI, 2.9 to 16.3; p<0.01). Conclusion: In general, individual physical tests are easy to do and a combination of those tests could be a sensitive indicator of L5 or S1 radiculopathy. Furthermore, the use of provocation tests could provide useful information, especially in proceeding therapeutic selective nerve root block.

• 정보보호학회논문지
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• 제33권3호
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• pp.391-399
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• 2023

본 논문에서는 경량 블록 암호인 PIPO-64/128, 256에 대해 T-table을 사용한 구현을 최초로 제시한다. 제안 방법은 최초 16개의 T-table을 요구하지만, 필요한 두 종류의 T-table이 순환 구조임을 보이고 T-table 개수를 줄여 구현하는 변형 방법을 추가로 제시한다. 제안 방법들의 T-table 수(코드 크기)-속도간 상충관계 분석을 위해 각각 변형 구현물을 Intel Core i7-9700K 프로세서 환경에서 평가한다. 평가를 통해 획득한 속도 최적화 구현은 TLU(Table-Look-Up) 레퍼런스 구현에 비해 PIPO-64/128, 256에서 각각 11.33, 9.31배, 비트 슬라이스(Bit Slice) 레퍼런스 구현에 비해 각각 3.31, 2.76배 향상된 속도를 갖는다.