• Journal of Veterinary Clinics
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• v.33 no.6
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• pp.351-355
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• 2016

This study was conducted to investigate reasons for culling of Chungcheong dairy herds and to investigate the relationships between cow parity, interval from calving to culling, or season and culling reasons. Lactation data from 826 cows on 9 dairy farms from 2013 to 2015, including reasons for culling, dates of birth, last calving, and culling, were analyzed. The overall culling rate was 29.8% (246/826), with mammary problems (23.2%) being the most prevalent reason for culling, followed by infertility (14.2%) and downer cow syndrome (11.0%). The culling rate varied among farms (18.8-43.1%, p < 0.05), but was greater in parity $4{\leq}(40.7%)$ than parities 1, 2, or 3 (17.9-23.6%), whereas the rate was less frequent during mid lactation (21.1%) than in early (36.2%) or late (42.7%) lactation. Moreover, the culling rate was greater during summer (35.8%) than other seasons (20.3-23.2%). Mammary problems, downer cow syndrome, and metabolic disorders were the more common reasons for culling during early lactation, whereas infertility was predominant during late lactation. Our data show that the culling rate in Chungcheong dairy herds was associated with cow parity, interval from calving to culling, and season, with the main reasons for the removal of cows from dairy herds being mammary problems, infertility, and downer cow syndrome.

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.9
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• pp.1214-1218
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• 2004

Data on 958 Karan Fries (KF) and 780 Karan Swiss (KS) cows, born during 1974 to 1992 at National Dairy Research Institute, Karnal were evaluated for causes of culling and their impact on milk performance and herd strength. Causes of culling were classified as voluntary culling (low milk yield) and involuntary culling (other than milk yield). The milk yield of cows was evaluated inretrospectively by estimating expected breeding value (EBV) on the basis of first lactation yield (FLY) and all available lactation yield (ALY). The culling rate of KF cows over the years varied from 10.89 (1988) to 33.92% (1991) with an overall average of 20.96% and in KS from 19.91 (1984) to 33.74% (1989) with an overall average of 25.01%. Reproductive disorders, teat and udder problems, low milk production, health and locomotive disorders were the major reasons of culling accounted respectively for 5.56, 4.97, 4.61, 3.18 and 2.24% of herd strength in KF cows. The corresponding causes of culling were 6.20, 6.26, 7.69, 1.49 and 2.67% of herd strength in KS cows. The involuntary culling of cows accounted for 82.4% in K F and 76.1% in KS cows of total culling. The average annual disposal rate in KF and KS was 26 and 30% whereas annual replacement rate was 24 and 26% respectively. The EBV of involuntary culled cows on the basis of FLY and ALY was 3,111 and 3,515 kg in KF; and 2,669 and 2,940 kg in KS cows respectively. The EBV of selected cows on the basis of FLY and ALY was 3,242 and 3,549 kg in KF and 2,893 and 3,245 kg in KS cows respectively. The average breeding value of involuntary culled cows was not significantly different from selected cows in both the herds. The high rate of involuntary culling of potential cows might be major factor responsible for declined performance and size in these herds. The results indicated that higher genetic gain (2.14% of herd average in KF and 3.49% of herd average in KS) could be obtained by restricting the involuntary culling (50% of total culling) through improved management practices and increasing replacement rate.

• IEMEK Journal of Embedded Systems and Applications
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• v.9 no.2
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• pp.61-66
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• 2014

Temporal disappearance of weather phenomena effect is frequently observed in flight simulator when large volume of terrain data are processed. This problem was solved by employing culling scheme at static ratio in the existing scheme. However, since this approach causes the irregular rendering speed according to volume of data, it is necessary to develop a new culling scheme to maintain steady rendering speed by adjusting the culling ratio dynamically. In this paper, we propose a new culling scheme to make use of distance of the visibility to determine culling ratio depending on volume of terrain data. The experimental results show that rendering speed is preserved by the proposed scheme without affecting the visuality at rendering the scene and weather phenomena effect together.

• Proceedings of the Korean Information Science Society Conference
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• 2002.04b
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• pp.640-642
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• 2002

본 논문에서는 게임엔진에서 쓰이는 Culling System 종류인 BSP, 포털, PVS에 대한 기본 개념과 각각의 장단점을 설명하였다. 그리고 상용게임엔진에서의 Culling System을 비교하고 여러게임엔진에서 어떤 Culling System이 사용되는지를 논술한다.

• Korean Journal of Computational Design and Engineering
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• v.8 no.2
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• pp.75-83
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• 2003

In this paper, OSP(Octal Space Partitioning) tree is proposed for the real time culling of infinite sets of geometries in interactive Virtual Environment applications. And MSVBSP(Modified Shadow Volume BSP) tree is suggested for the occlusion culling. Experimental results show that the OSP and MSVBSP tree are efficiently implemented in real time rendering of interactive geometries.

• Journal of the korean veterinary medical association
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• v.15 no.2
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• pp.73-84
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• 1979

The detailed culling cases of dairy cattles by diseases are surveyed in the northern parts of Gyounggi-do for a year of 1976 and the results are as follows: 1. The total rates of culling cases are $3.47\~5.64\%$. 2. The culling rates by disease

• The KIPS Transactions:PartA
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• v.15A no.1
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• pp.1-8
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• 2008

An occlusion culling method, one of visibility culling methods, excludes invisible objects or triangles which are covered by other objects. As it reduces computation quantity, occlusion culling is an effective method to handle complex scenes in real-time. But an existing common occlusion culling method, such as hardware occlusion query method, sends objects' data twice to GPU and this causes processing overheads once for occlusion culling test and the other is for rendering. And another existing hardware occlusion culling method, VCBP, can test objects' visibility quickly, but it neither test bounding volume nor return test result to application stage. In this paper, we propose a single pass occlusion culling method which uses temporal and spatial coherency, with effective occlusion culling hardware architecture. In our approach, the hardware performs occlusion culling test rapidly with cache on the rasterization stage where triangles are transformed into fragments. At the same time, hardware sends each primitive's visibility information to application stage. As a result, the application stage reduces data transmission quantity by excluding covered objects using the visibility information on previous frame and hierarchical spatial tree. Our proposed method improved maximum 44%, minimum 14% compared with S&W method based on hardware occlusion query. And the performance is increased 25% and 17% respectively, compared to maximum and minimum performance of CHC method which is based on occlusion culling method.

• IEMEK Journal of Embedded Systems and Applications
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• v.10 no.2
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• pp.73-79
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• 2015

Dynamic culling scheme is usually implemented to handle overhead caused by rendering the massive large-scale terrain data in flight simulator. However, existing culling scheme without considering altitude is not suitable for flight simulator due to additional computational overhead. To solve this problem, in this paper, we propose hybrid approach by applying two dynamic culling schemes depending on altitude. In addition, we remove unnessary computational overhead by creating different z-map resolution when aircraft changes its altitude. The proposed scheme is implemented with open graphic library and tested with real terrain data. Through the experimental results, we can recognize the improved rendering speed about 8 to 73 percents as compared to existing scheme.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.8
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• pp.89-96
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• 2007

In this paper, we designed 3D graphics rasterizer with a culling and clipping for the efficient 3D graphics accelerator. The proposed rasterizer is implemented for the mobile system and process frustum culling, back face culling, Y-axis clipping and X-axis clipping. The rasterzier consists of triangle setup, edge walk and span process unit. Each unit of rasterzier is designed with a culling and clipping. It supports goraud shading with 16 bits depth values and 16 bits color values. The estimated performance of proposed rasterizer is 52M pixels per second.

• Korean Journal of Computational Design and Engineering
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• v.8 no.2
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• pp.65-74
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• 2003

For virtual reality, virtual manufacturing system, or simulation based design, we need to visualize very large and complex 3D models which are comprising of very large number of polygons. To overcome the limited hardware performance and to attain smooth realtime visualization, there have been many researches about algorithms which reduce the number of polygons to be processed by graphics hardware. One of these algorithms, occlusion culling is a method of rejecting the objects which are not visible because they are occluded by other objects, and then passing only the visible objects to graphics hardware. Existing occlusion culling algorithms have some shortcomings such as the required long preprocessing time, the limitation of occluder shape, or the need for special hardware implementation. In this study, an efficient occlusion culling algorithm is proposed. The proposed algorithm reads and analyzes Z-buffer of graphics hardware using Microsoft DirectX, and then determines each object's visibility. This proposed algorithm can speed up visualization by reading Z-buffer using DirectX which can access hardware directly compared to OpenGL, by reading only the region to which each object is projected instead of reading the whole Z-Buffer, and the proposed algorithm can perform more exact visibility test by using simplified model instead of using bounding box. For evaluation, the proposed algorithm was applied to very large polygonal models. And smooth realtime visualization was attained.