• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2002년도 춘계학술대회 논문집
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• pp.86-89
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• 2002

Due to extremely large reduction of area or extrusion ratio in ordinary production of extruded profiles, anisotropy is naturally induced by large severe deformation during the extrusion process. Therefore, the anisotropic properties play a great role in the post processing of extruded profiles, such as in bending. Moreover, undesirable deformation will be involved when the deformation-induced anisotropy is ignored. In order to observe the deformation-induced anisotropy of the thin-walled product, the proposed algorithm is applied to some chosen industrial extrusion processes. In the resent work, the method for prediction of deformation-induced anisotropy employing the Barlats six-component yield potential to the rigid-plastic finite element method is proposed. The proposed algorithm is verified with the comparison to the crystallographic texture analysis, and then applied to the C-section exclusion process using a square die. The predicted anisotropy is then compared with the experimental and computational observations for validating the proposed algorithm.

• 소성∙가공
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• 제11권8호
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• pp.724-730
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• 2002

Due to extremely large reduction of area or extrusion ratio in ordinary production of extruded profiles, anisotropy is naturally induced by large severe deformation during the extrusion process. Therefore, the anisotropic properties play a great role in the post processing of extruded profiles, such as in bending. Moreover, undesirable deformation will be involved when the deformation-induced anisotropy is ignored. In order to observe the deformation-induced anisotropy of the thin-walled product, the proposed algorithm is applied to some chosen industrial extrusion processes. In the present work, the method for prediction of deformation-induced anisotropy employing the Barlats six-component yield potential to the rigid-plastic finite element method is proposed. The proposed algorithm is verified with the comparison to the crystallographic texture analysis, and then applied to the C-section extrusion process using a square die. The predicted anisotropy is then compared with the experimental and computational observations for validating the proposed algorithm.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권4호
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• pp.1730-1747
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• 2018

Multi-view video plus depth (MVD) is a mainstream format of 3D scene representation in free viewpoint video systems. The advanced 3D extension of the high efficiency video coding (3D-HEVC) standard introduces new prediction tools to improve the coding performance of depth video. However, the depth video in 3D-HEVC is time consuming. To reduce the complexity of the depth video inter coding, we propose a fast coding unit (CU) size and mode decision algorithm. First, an off-line trained Bayesian model is built which the feature vector contains the depth levels of the corresponding spatial, temporal, and inter-component (texture-depth) neighboring largest CUs (LCUs). Then, the model is used to predict the depth level of the current LCU, and terminate the CU recursive splitting process. Finally, the CU mode search process is early terminated by making use of the mode correlation of spatial, inter-component (texture-depth), and inter-view neighboring CUs. Compared to the 3D-HEVC reference software HTM-10.0, the proposed algorithm reduces the encoding time of depth video and the total encoding time by 65.03% and 41.04% on average, respectively, with negligible quality degradation of the synthesized virtual view.

• 열처리공학회지
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• 제31권6호
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• pp.275-282
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• 2018

Two different modes of rolling were applied to control the texture development in tantalum sheet. In the conventional uni-directional rolling, the typical rolling textures of a body-centered cubic metal which was primarily composed of <110>//(rolling direction) was developed. In a cross rolling where the specimen was rotated by $90^{\circ}$ between each pass, the rotated cube components, i.e. {100}<011> were greatly reinforced. The prediction of lattice rotation by the full-constraint Taylor model showed that the high stability and the symmetry of the rotated cube components caused their strengthening in cross-rolling. The two specimens were heated to $1,100^{\circ}C$ at $9^{\circ}C/min$and held for 1 hour for annealing, then cooled to room temperature in atmosphere. In spite of the significant difference in the deformation textures, the annealing textures were very similar. They developed strong <111>//(plane normal) components with negligible intensity at the rotated cube components, which was attributed to the negligible capability of the latter components to provide effective recrystallized grains.

• 한국수자원학회논문집
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• 제36권6호
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• pp.1035-1046
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• 2003

TOPMODEL의 지하수면길이 분포에 대한 예측능력을 평가하기 위해 2개 기본가정과 지하수면깊이에 대한 지배방정식을 검증하였다. 검증에는 토양두께가 얇은 급경사 사면의 수문관측과 토양조사 자료를 이용하였다. 조사사면에서 지하수면반응과 토양의 수리적 특성은 지형경사와 평행하는 수리경사, 지하수면깊이에 지수함수적으로 감소하는 투수량계수 등과 같은 TOPMODEL의 기본가정과 일치하였다 토양의 투수량계수감소율(f)과 토성은 지표부터 깊이 0.3m까지 사면전체에서 공간적으로 균질하지만, 토성과 f의 수직적인 변화로 깊이 0.3m 아래부터 공간적으로 불균질한 특성을 보인다. 조사사면에서 TOPMODEL의 지배방정식은 f값이 공간적로 균질한 깊이의 지하수면깊이 분포를 예측하는데 적용할 수 있는 것으로 나타났다.

• 한국콘텐츠학회논문지
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• 제16권10호
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• pp.514-521
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• 2016

HEVC 비디오 압축 표준은 기존 비디오 표준보다 더 다양한 블록 구조와 예측 모드를 사용함으로써 우수한 부호화 성능을 제공하나, 최적의 블록 크기 및 예측 모드를 결정하기 위한 RDO(Rate Distortion Optimization)과정으로 인해 연산량이 많다는 단점을 가진다. 이를 개선하기 위해 본 논문에서는 화면 내 예측 수행 전 CU영역의 모멘트 값을 계산하고 이를 CU영역의 텍스쳐 복잡도로 이용하여 CU의 분할 여부를 결정하는 모멘트 기반의 고속 CU크기 결정 방법을 제안한다. 제안하는 방법은 기존의 방법을 차용하여 CU영역의 밝기 값에 대한 분산 값을 계산하여 영역의 텍스쳐 평평도를 추정하고, 추가로 CU영역의 밝기 값에 대한 비대칭도를 계산하여 CU영역을 이루는 밝기 값 분포의 비대칭성 정도를 측정한 뒤 이를 조합하여 기존 방법보다 더 정밀하게 텍스쳐 복잡도를 측정하였으며, 이를 RDO과정 중 현재 CU의 분할 여부를 결정하는데 이용하여 기존의 부정확한 CU분할 여부 결정 방법을 개선시킨 고속 CU크기 결정 방법을 제안한다. 제안 방법의 실험 결과는 기존 방법 대비 4.2%의 BD-rate 감소를 보여주며, HM-10.0과 비교하여 BD-rate는 1.1% 증가하였고, 인코딩 시간이 32% 절감되었다.

• Applied Biological Chemistry
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• 제41권2호
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• pp.153-159
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• 1998

국내산 후지 사과의 주요 내부 품질 요인인 당도, 수분 함량, 경도 및 산 함량을 근적외 분광분석법에 의해 동시에 신속, 정확하게 비파괴 측정할 수 있는지의 가능성을 조사하였다. 굴절당도계에 의한 당도, 동결 건조법에 의한 수분 함량, texture analyzer에 의한 경도 및 알칼리 적정법에 의해 얻어진 산 함량 데이터와 근적외 영역의 흡광도 데이터 사이에 각각 중회귀분석을 행한 결과, 당도, 수분 함량, 경도 및 산 함량의 측정 오차(SEP)는 각각 $0.50^{\circ}Brix,\;0.64%,\;0.14kg/cm^2$ 및 0.07%이었다. 이로서 근적외 분광 분석법을 응용하여 사과의 당도와 수분 함량은 비파괴적으로 신속, 정확하게 측정 가능함을 알 수 있었으나, 경도와 산 함량의 측정 정확도는 다소 낮은 편이었다.

• 한국환경복원기술학회지
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• 제2권3호
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• pp.83-92
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• 1999

To investigate the influence of forest road characteristics and site conditions on the stability of forest-road in granite area, four forest roads had been selected in Kyongbuk regions. The total of 13 road characteristic variables were evaluated by the discriminant analysis. The factors influencing the stability of forest road were bed rock, slope length, coverage, hardness, side-ditch erosion and road width. But aspect and soil texture were not significant for the stability in this area. In the correlation between forest environment and road structure, hardness and bed rock was highly significant in stability group, and coverage and side-ditch erosion was highly significant in instability group. 75 of 175 segments were instable whereas the others were stable. The centroids value by discriminant function in the stability and instability were estimated to 3.0585 and -1.9116, respectively. The stability criterion of forest road was discriminated from the centroids value of the each group. The main factors contributing the stability of forest road were significant in order of side-ditch erosion, coverage, soil texture, elevation, gradient, slope length and construction year. The prediction rate of discriminant function for stability evaluation of forest road was as high as 97.44%. In conclusion, the forest road structure factors such as length, coverage and slope gradient were controlled by construction techniques. If the factors like those should be considered in design, construction and forest road management, the stability of forest road may increase more. And also, it is necessary to take slope protection measures like small terraces and retaining walls for stability of cut slope.

• 농업과학연구
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• 제48권4호
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• pp.843-853
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• 2021

The objectives of this paper were to simply estimate soil loss levels as caused by wind in reclaimed tidal flat land (RTFL) and the threshold wind velocity in the RTFL. For this experiment, RTFL located at Haenam Bay was selected and a total of 150 soil samples were collected at the Ap horizon from the five soil series. The particle distribution curves, including the limit of the non-erodible particle size (D > 0.84 mm) for each Ap horizon soil, show that the proportions of non-erodible particle sizes that exceeded 0.84 mm were 4.3% (Taehan, TH), 8.9% (Geangpo, GP), 0.5% (Bokchun, BC), 1.6% (Poseung, PS) and 1.4% (Junbook, JB), indicating that the amount of non-erodible soil particles increased with an increase in the sand content. The average monthly, daily and instantaneous wind velocities were higher than the threshold friction velocity (TFV) calculated according to the dynamic velocity (V_d) by Bagnold, while the average monthly wind velocity was lower than those of the TFV suggested by the revised wind erosion equation (RWEQ) and wind erosion prediction system (WEPS). The susceptible proportions of erodible soil particles from the Ap horizon soil samples from each soil series could be significantly influenced by the proportion of sand particles between 0.025 and 0.5 mm (or 0.84 mm) in diameter regardless of the threshold wind velocity. Thus, further investigations are needed to estimate more precisely soil erosion in RTFL, which shows various soil characteristics, as these estimations of soil loss in the five soil series were obtained only when considering wind velocities and soil textures.

• 한국산림과학회지
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• 제112권4호
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• pp.490-501
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• 2023

본 연구에서는 강우의 침투과정 및 수분 재분포 현상을 분석하기 위하여 실내 컬럼실험을 수행하였으며, 토층 내 함수비를 효율적으로 측정하기 위하여 딥러닝 기법 중 하나인 합성곱신경망(Convolutional Neural Network, CNN)을 사용하여 함수비 예측 모델을 구축하였다. 컬럼실험으로부터 획득된 디지털 이미지를 구축된 CNN 모델에 적용한 결과 시간에 따른 토층별 함수비를 효과적으로 측정할 수 있었으며, 토층별로 설치된 함수비 센서에 따른 함수비와도 비교적 잘 일치하는 것으로 나타났다. 결과적으로 CNN을 활용하여 토층 내 연속적인 함수비 분포를 파악하는 것이 가능하였으며, 토성 및 지반 함수비 조건에 따른 침투 과정을 효과적으로 분석할 수 있었다.