• Annual Conference on Human and Language Technology
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• 1992.10a
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• pp.237-248
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• 1992

본 논문에서는 통계적인 특징 추출 방법을 사용하여 샘물체로 필기된 한글을 고속으로 인식하는 방법을 소개한다. 대부분이 직선 성분으로 이루어진 한글의 특성을 이응하기 위하여 입력 영상으로부터 수평, 수직, 사선, 역사선의 방향 성분을 추출하며, 검은 화소의 밀도에 따라 동적으로 그물을 결정함으로써 획 간의 접촉 변형에 무관한 특징 벡터를 추출한다. 이와 같은 통계적 특징 추출 방법은 크기 정규화나 세선화 과정이 필요없으며, 또한 샘물체라는 필기 형태의 제약에 의해 정합 대상 부류의 수가 현저히 줄어들기 때문에 인식에 소요되는 시간을 상당히 줄일 수 있음은 물론, 인식률을 향상시켰다. 제안된 방법의 타당성을 검증하기 위하여 샘물체로 필기된 KS 완성형 한글 2,350자에 대해 실험한 결과, 평균 90% 이상의 인식률을 보이며, IBM PC 486(33MHz)상에서 문자당 평균 0.17초의 인식 속도를 보임으로써, 실용적인 고속 OCR 시스템의 개발 가능성을 확인할 수 있었다.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.11a
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• pp.203-204
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• 2022

This study reviewed the impact resistance properties according to the thickness of concrete as part of a research on the protection technology for high-velocity projectile that may occur during an explosion of small green energy facilities such as a hydrogen station and an energy storage system.

• IEMEK Journal of Embedded Systems and Applications
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• v.1 no.1
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• pp.20-23
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• 2006

본 논문은 MB-OFDM UWB(Multi Band-Orthogonal Frequency Division Multiplexing Ultra Wide Band) 시스템을 위한 변형된 가변 파라미터를 이용한 큐빅 인터폴레이터를 제안한다. MB-OFDM UWB 시스템은 고속의 동작속도가 필요하기 때문에, 기존 가변 파라미터를 이용한 큐빅 인터폴레이터에 병렬 처리 기술과 파이프라인 기법을 동시에 적용한다. 실험 결과, Stratix II 2S60F101020C3 디바이스를 타켓으로 최대지연경로 속도와 최대지연경로 주기가 각각 최대 88.79MHz와 11.262ns가 되었고, 동작속도는 최대 대략 200% 이상 향상되었음을 알 수 있다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1992.10a
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• pp.91-95
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• 1992

현재 대부분의 공작기계에서는 모터의 동력을 주축으로 전달하기 위해서 커플링, 밸트,기어 등을 사용하고 있지 만 주축이 고속회전할 수록 커플링 구동방법에서는 주축과 모터의 미스얼라인먼트에 의한 진동과 소음이 커지고 벨트 구동방법에서는 원심력에 의한 벨트 장력의 증가 및 벨트의 파손현상, 벨트와 풀리간의 미끄럼현상 등이 발생하며, 기거 구동방법에서는 기어간의 금속접촉에 의한 진동과 소음이 증대하게 된다. 본 연구에서는 모터내장형 주축의 동특성을 체계적으로 해석하기 위해서 유한요소모델을 도입하였다. 특히 공작기계 주축은 세장비가 비교적 작기 때문에 Timoshenko보 이론으로 모델화하였고, 여러장의 얇은 철심용 강판들도 적층된 내장형 모터의 회전부(rotor)는 굽힘변형 및 전단변형에 대해서 상당 수준의 강성효과를 나타내기 때문에 질량효과 외에도 그 강성효과를 수학적 모델에서 고려하였다, 또한 진동실험 결과로 부터 모터회전부의 강성특성을 규명하는 방법을 제시하였으며, 제안된 규명방법의 유용성은 모터내장형 주축에 대한 모드매개변수의 이론값과 실험값을 비교함으로써 입증하였다.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.7
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• pp.70-77
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• 2010

Motion estimation occupies most of the required computation in video compression, and many fast search algorithms were propsoed to reduce huge computation. SAD (sum-of-absolute difference) calculation is the most computation-intensive process in the motion estimation. Early termination is widely used in SAD calculation, where SAD calculation is terminated and it proceeds to next search position if partial SAD during SAD calculation exceeds current minimum SAD. In this paper, we proposed a modified 3-step search algorithm for effective early termination where only search order of search positions are adaptive rearranged. Simulation results show that the proposed motion estimation algorithm reduces computation by 17~30% over conventional 3-step search algorithm without extra computation, while maintaining same performance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.11C
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• pp.929-939
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• 2010

The growth of multimedia technology forces the development of video detection for large database management and illegal copy detection. To meet this demand, this paper proposes a fast video detection method to apply to a large database. The fast video detection algorithm uses spatial features using the gray value distribution from frames and temporal features using the temporal similarity map. We form the video signature using the extracted spatial feature and temporal feature, and carry out a stepwise matching method. The performance was evaluated by accuracy, extraction and matching time, and signature size using the original videos and their modified versions such as brightness change, lossy compression, text/logo overlay. We show empirical parameter selection and the experimental results for the simple matching method using only spatial feature and compare the results with existing algorithms. According to the experimental results, the proposed method has good performance in accuracy, processing time, and signature size. Therefore, the proposed fast detection algorithm is suitable for video detection with the large database.

• Composites Research
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• v.37 no.3
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• pp.143-149
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• 2024

This paper measures the mechanical properties of corrugated cardboard, an eco-friendly packaging material, and applies these measurements to the MAT_PAPER model in LS-DYNA for finite element analysis. Although MAT_PAPER is primarily designed for modeling the behavior of paper, this research demonstrates its applicability to corrugated cardboard as well. Tensile, compression, and shear behaviors of a corrugated cardboard were measured and analyzed, and based on these results, six yield surfaces were derived and integrated into the MAT_PAPER model. By comparing the finite element analysis of the material tests and the low velocity collapse analysis of the corrugated cardboard square boxes with each experimental results, it was shown that the behavior of corrugated cardboard could be equivalently considered well by the MAT_PAPER model. However, since the model is not rate-dependent, the high strain rate properties of liner materials were measured and used for strain rate correction. Consequently, this matches well with the results of the high-speed compression tests of the corrugated cardboard square boxes.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.2
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• pp.603-608
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• 2014

In many manufacturing such as the components of airplane and automobile, aluminum alloys(Al2024) which remarkable in low specific gravity and high strength have been utilized effectively. Face milling machining technology for surface roughness quality of workpiece has been applied in these fields. A face milling machining with chamfered throw away type insert tip can produce a perfect flat surface only in theory. But It is impossible because of many unwanted factors, namely, cutting temperature, plastic deformation, dynamic effect, etc. In this paper, experimental investigations are performed to improve surface roughness after high speed machining of Al2024 using qualified face milling cutter body for high speed machining.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.32 no.1
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• pp.37-44
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• 2019

A bond-based peridynamic model has been reported dynamic fracture characteristic of brittle materials through a simple constitutive model. In the model, each bond is assumed to be a simple spring operating independently. As a result, this simple bond interaction modeling restricts the material behavior having a fixed Poisson's ratio of 1/4 and not being capable of expressing shear deformation. We consider a state-based peridynamics as a generalized peridynamic model. Constitutive models in the state-based peridynamics are corresponding to those in continuum theory. In state-based peridynamics, thus, the response of a material particle depends collectively on deformation of all bonds connected to other particles. So, a state-based peridynamic theory can represent the volume and shear changes of the material. In this paper, the perfect plasticity is considered to express plastic deformation of material by the state-based peridynamic constitutive model with perfect plastic flow rule. The elastic-plastic behavior of the material is verified through the stress-strain curves of the flat plate example. Furthermore, we simulate the high-speed impact on 3D granite model with a nonlocal contact modeling. It is observed that the damage patterns obtained by peridynamics are similar to experimental observations.

• International Journal of Highway Engineering
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• v.6 no.1 s.19
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• pp.25-36
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• 2004

The total length of paved roads in Korea is 67,265 Km, and among these roads, about 40% of the national highways and 98% of local roads are paved with asphalt concrete. The major distress to asphalt pavement is rutting and fatigue crack. The permanent deformation including rutting accounts for about 75% of this distress. UTW(Ultra-Thin Whitetopping), which is known for its high-quality performance in asphalt pavement with rutting and cracking, seems to reduce maintenance costs significantly if it is used as the maintenance/repair method for domestic asphalt pavement. In the research, static load test was conducted to establish a behavior of Whitetopping under traffic and environmental condition. It showed that the effect of the thickness of the concrete layer and the temperature change was significant. In addition, the tensile strain as the wheel load position was close to interior and edge of concrete slab were increased up to 75% of maximum tensile strain. It showed that joint spacing must be considered in UTW design procedure.