• Elastomers and Composites
• /
• v.47 no.4
• /
• pp.341-346
• /
• 2012

Injection molding is one of the widely used polymer processing operations. It is being used for not only conventional injection molding but gas injection molding, water injection molding, and injection compression molding. Injection compression molding involves injection and compression operation, and it gives uniform physical property and high dimensional quality of product. In this study, injection compression characteristics for various product shapes have been investigated by computer simulation. Product containing side wall showed not much effective in injection compression molding since wall thickness direction was perpendicular to the compression direction. Uniform and low shrinkage was observed in injection compression molding comparing conventional injection molding. Subsequently injection compression molding can be used for molding precise product. Optimal injection compression molding condition was obtained using design of experiment for plastic lens and the results were compared with conventional injection molding.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.26 no.1
• /
• pp.23-27
• /
• 2016

This study investigates the effect of carbon fiber sheet (CFS) and carbon fiber strand sheet (CFSS) on the fatigue resistance and compressive strength of RC slabs. The results of a comparison of the number of equivalent cycles between the CFS- and CFSS-reinforced RC slab test specimens obtained from a fatigue test indicate that the CFSS-reinforced RC slab has 1.2~1.3 times greater effect of reinforcement than the CFS-reinforced RC slab. This study also indicates that the fatigue resistance of the CFS- and CFSS-reinforced RC slabs is ensured when the compressive strength of concrete is not lower than the specified design strength prescribed in the Specifications for Highway Bridges but is not ensured when the compressive strength of concrete is lower than the specified design strength, although the effect of reinforcement is secured.

• Journal of Labour Economics
• /
• v.39 no.4
• /
• pp.31-56
• /
• 2016

This study analyzes the effect of a minimum wage on the wage compression within Korean establishments. The results are as follows. Firstly, increases of a ratio of workers who get minimum wage within establishments have a effect to compress the wage distribution within establishments. Secondly, the establishment average wages get lower as their minimum wage ratios get larger. In this situation, high wage group's wages fall deeply than low wage group's these. Thirdly, the relative wages of high wage group to low wage group tend to be small as their minimum wage ratios get larger. To conclude, a increase of minimum wage has a effect to raise low wage workers' wages directly, and to reduce high wage workers' wages or increase rates indirectly. And the wage distributions are compressed as a result. So government's policy to increase minimum wage will have a result in reducing wage inequality.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2003.05a
• /
• pp.595-598
• /
• 2003

본 논문에서는 방사선투영영상을 기존 압축방법인 JPEG 압축과 새로운 표준으로 채택중인 JPEG2000을 적용하여 압축율 및 영상의 품질을 비교 실험하였다. 기존의 의료영상압축 표준의 하나인 JPEG 압축은 압축비율이 높아짐에 따라 블륵킹 현상의 발생으로 원 영상이 회손되는 압축의 한계를 인식하고 있다. 따라서 원 영상의 보호와 압축율 증가의 두 가지 면을 만족시키기 위해 Wavelet 을 사용하는 JPEG2000을 실험 평가하여 의료영상압축에 적용하고자 한다. 실험대상으로 환자 10명 정상인 10명의 투영영상을 사용하였으며, 영상의 품질, 손상도 등을 평가하기 위해 PSNR( Peak Signal to Noise Ratio )과 판독의에 의한 ROC( Receiver Operating Characteristic )분석을 실행하였다. 실험결과, 영상의 품질, 손상도를 평가하기 위한 PSNR 은 15:1 압축에서 $46.05{\pm}1.1dB$의 값을 얻었으며, JPEG의 같은 압축비율에 비해 $1.78{\pm}0.1dB$의 값이 높음을 알 수 있었다. 종합적으로 3명의 판독의에 의해 ROC 분석을 실행한 결과 15:1의 압축비율에서 압축비율과 품질을 종합하였을 때 진단에 적합한 최적 압축비율임을 보였다.

• Proceedings of the Acoustical Society of Korea Conference
• /
• autumn
• /
• pp.135-138
• /
• 2001

오늘날 오디오 포맷의 대부분은 마스킹 효과를 이용한 손실 압축 기법(lossy coding)이다. 그러나 고음질을 요구하는 매니아가 있고 DVD등 차세대 멀티미디어 포맷으로 무손실 오디오 압축기법이 요구되고 있고 이를 위해 일반적인 무손실 데이터 압축방법인 PkZip 등으로 압축할 경우 압축비가 약 1.07:1 밖에 되지 않으므로 적절하지 못하여, 디지털 오디오 데이터를 위한 무손실 압축 알고리즘의 연구가 필요하게 되었다. 본 논문에서는 플래이밍(Framing), 상호상관제거(intrachannel decorrelation), 엔트로피 코딩(Entropy coding) 의 세가지 단계로 구성되는 일반적인 오디오 무손실 압축 기법을 효율적으로 압축하기 위해 wavelet transform을 적용한 알고리즘은 제안한다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• fall
• /
• pp.23-26
• /
• 2021

본 논문에서는 동적 포인트 클라우드 압축 표준인 V-PCC 을 기반으로 고밀도 동적 메쉬 데이터를 압축하는 방법을 제안한다. 제안하는 방법은 정점마다 색상 값을 갖는 고밀도 동적 메쉬 데이터 압축 구조로 정점마다 갖는 위치 정보와 색상정보는 V-PCC 를 통해 압축을 수행하고 정점들의 연결정보는 TFAN 기술을 통해 압축을 수행한다. 이때 V-PCC 를 통해 복원된 정점의 순서와 TFAN 을 통해 복원된 연결정보의 정점 인덱스 정보는 복원 후 변경되어 둘 사이를 매핑 해주기 위한 방법이 필요하다. 본 논문에서는 부호화기에서 3D morton 코드 기반으로 원본 정점과 V-PCC 를 통해 복원된 정점을 효과적으로 매핑하는 방법을 제안한다. 제안하는 메쉬 압축 방법은 기존 MPEG-4 의정적 메쉬 데이터 압축 표준인 SC3DMC 와의 비교를 통해 V-PCC 기반 동적 메쉬 데이터 압축의 효율성을 보인다.

• The Journal of the Korea Contents Association
• /
• v.4 no.1
• /
• pp.90-99
• /
• 2004

With the spread of internet, the digitalization and the knowledge informatization are in progress rapidly. Specially, numerous users make the various works and use the services on the web. For the most part, these works make use of the XML The XML shines the reusing of the documents because it is separated from contents and sues. Also, it can re-define the logic structure of the document for requirement of the developer. However, the XML document’s size is much larger than common text document because it handles the document type and adds numerous tags for representing structure of the document. To utilize the limited storage devices of Palmtop, PDA and so u, it is necessary to compress and handle the documents efficiently. Recently, the compression techniques for efficiently handling and compressing the XML documents are under way to solve this problem. But most of the existing researches don't support the query processing for the compressed XML documents. In this paper, we design and implement the XML compression algorithm that compresses the XML document and Processes the query of compressed XML document faster and more efficiently than previous techniques.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.13 no.12
• /
• pp.2693-2700
• /
• 2009

This paper proposes an effective compression method to utilize the 3D integral image with large amount of data obtained by a lens array in various applications. The conventional compression methods for still images exhibit low performance in terms of coding efficiency and visual quality, since they cannot remove the correlation between elemental images. In the moving picture compression methods, 1D scanning techniques that produce a sequence of elemental images are not enough to remove the directional correlation between elemental images. The proposed method effectively sequences the elemental images from an integral image by the 2D referencing technique and compresses them using the multi-frame referencing of H.264/AVC. The proposed 2D referencing technique selects the optimal reference image according to vertical, horizontal, and diagonal correlation between elemental images. Experimental results show that compression with the sequence of elemental images presents better coding efficiency than that of still image compression. Moreover, the proposed 2D referencing technique is superior to the 1D scanning methods in terms of the objective performance and visual quality.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.42 no.5
• /
• pp.607-616
• /
• 2022

Corrosion and degradation of reinforced structures due to abnormal climates and natural disasters further accelerate the aging of structures. Coping with the decrease in structure performance, many old structures are being repaired and reinforced with low-weight and high-strength materials such as glass fiber composite material (GFRP). To further contribute, this paper focus on a more economical and eco-friendly material, basalt fiber composite (BFRP), which provide a more effective lateral constraint effect for seismic reinforcement. The main variables considered in this study are the curing temperature during the manufacturing of BFRP and the material characteristics of the target concrete member. The lateral constraint reinforcement effect was investigated through the evaluation of the performance of normal concrete and those with improved durability through fiber reinforcement. The reinforcement effect was 3.15 times for normal concrete and 3.72 times for fiber reinforced concrete, and the difference in reinforcement effect due to the improvement of the durability characteristics of the compression member was not significant. Lastly, the performance of the BFRP was compared with the results of the GFRP reinforcement from the previous study. The effect of the BFRP reinforcement was 1.18 times better than that of the GFRP reinforcement.

• Magazine of the Korea Concrete Institute
• /
• v.7 no.2
• /
• pp.146-154
• /
• 1995

I n this paper, an experimental research was carried out to investigate the confinement effect of spiral reinforcements in concrete column specimens subjected to t.he concentric axial corn pressive loads. Main variables were the compressive strengths of concrete of 27.2, 62.4 and 81.2 MPa, and the spacings of spirals of 120, 60, 40, 30, 25 and 20mm. and the yield strengths of spir als of 451 and 1375MPa, respectively. For the same volumetric ratio and yield strength of spir als, it was shown that the strength increment of confined concrete was almost same regardless of the strength of unconfined concrete, however, the axial stram at maximum stress was decreas ed with increasing of the compressive strength of unconfined concrete.