• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.10a
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• pp.400-403
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• 2022

This paper propose a GPU-based N-body collision detection algorithm using LBVH (Linear Bounding Volume Hierarchy) technique. This algorithm introduces a new modified Morton code scheme where the codes use an information about how much each body takes a space in the screen space. This scheme improves the GPU sorting performance of the N-Body because it culls out invisible objects in natural manner. Through the experiments, we verifies that the proposed algorithms can have at least 15% performance improvement over the existing methods

• International Journal of Fluid Machinery and Systems
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• v.9 no.1
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• pp.47-55
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• 2016

The portable hydraulic turbine we previously developed for open channels comprises an axial flow runner with an appended collection device and a diffuser section. The output power of this hydraulic turbine was improved by catching and accelerating an open-channel water flow using the kinetic energy of the water. This study aimed to further improve the performance of the hydraulic turbine. Using numerical analysis, we examined the performances and flow fields of a single runner and a composite body consisting of the runner and collection device by varying the airfoil and number of blades. Consequently, the maximum values of input power coefficient of the Runner D composite body with two blades (which adopts the MEL031 airfoil and alters the blade angle) are equivalent to those of the composite body with two blades (MEL021 airfoil). We found that the Runner D composite body has the highest turbine efficiency and thus the largest power coefficient. Furthermore, the performance of the Runner D composite body calculated from the numerical analysis was verified experimentally in an open-channel water flow test.

• Tribology and Lubricants
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• v.39 no.2
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• pp.35-42
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• 2023

Bearing is a mechanical component that supports loads and transmits rotation. As the application of high-value-added products such as semiconductors, aviation, and robots have recently become diverse and more precise, an accurate bearing performance prediction and evaluation technology is required. Bearing performance evaluation can be divided into evaluations based on bearing theory and on numerical analysis. An evaluation based on numerical analysis is a technique that has been highlighted because the problems that remained unsolved owing to time problems can be solved through recent developments in computers. However, current studies have the disadvantage of not considering the essential changes over time and bearing rotation. In this study, bearing performance evaluation based on rigid body dynamic analysis considering rotation and load over time is performed. Rigid body dynamic analysis is performed for deep groove ball bearing to calculate the load applied by the ball. The reliability of the analysis is verified by comparing it with the results calculated using bearing theory. In addition, rigid body dynamic analysis is performed for automotive wheel bearings to calculate the contact angle and load applied by the ball for cases where axial load and radial load are applied, respectively. The effect of rotation and load over time is evaluated from these results.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.2566-2569
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• 2003

An alternative optimal control law formulation is introduced and compared with two different control law, a conventional linear quadratic regulator and the control law based on game theory. This formulation eliminates the undesired modes of the system by the projection of a controller onto the subspace orthogonal to that of the bad modes. In conventional LQR control law, the control performance can be improved only by using proper weighting matrices in performance index, normally, with high cost. The control law formulation by game theory may provide various ways to obtain the desired performance. The control law modified by the elimination of bad modes provides efficient ways to get rid of an undesired performance since it eliminates the exact modes which cause the bad control performance.

• Journal of Korean Institute of Industrial Engineers
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• v.27 no.1
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• pp.95-102
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• 2001

The design of automobile body assembly line is one of essential parts for improving the process performance. The major objective of this research is to develop a performance evaluation model for automobile assembly line using a closed queueing network(CQN) and simulation method. In this study we used a two-step approach to compute the performance of the assembly line : first, we used CQN model considering assembly line equipments and the line operating time under the assumption of no failure, and second we used a well-known simulator FACTOR/AIM. Finally we implemented this model on a K automobile company and we have shown the sample results of automobile body assembly line.

• Korean Journal of Applied Biomechanics
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• v.16 no.1
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• pp.55-63
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• 2006

The purpose of this study is to prove the kinematical characteristics of Deff motion, the high bar performance, in terms of flying phases so that we can provide basic sources for improving gymnastic performance. To do this, we selected and analyzed the performance of two athletes who did Deff motion in the high bar competition of male artistic gymnastic in the 22nd Universiade 2003 Daegu. We drew the conclusions from the kinematical factors that were came out through analyzing three-dimensional cinematography of the athletes' movements, by using a high speed video camera. To make a successful performance, a performer releases the bar at a height of a high bar vertically and at a height of 82cm horizontally, and the flying performance should be made without moving forward, as maintaining the proper balance, in order to rise over 118cm high during the flying phase. When the performer is releasing the bar, an increase of the vertical speed in the center of the body and extension of a knee joint and a hip joint contribute to increasing a flying height. And when the moving body is twisted, leaning to left side is caused by the winding movement of a knee joint, which causes an unstable bar grasp. To grasp the bar stably, just before releasing the performer should gain propulsive force from twisting rotation through increasing the speed of shoulder rotation. And before the peak point, the performer should make sure of a body rotation distance over $164^{\circ}$ so that he or she can do an aerial rotary performance smoothly. When grasping the high bar, the center of the body should be above the bar and the angle of shoulder rotation should be maintained close to $540^{\circ}$ simultaneously. he high point performance(S1) has more speed on an ascending phase and less speed on a descending phase than the low point performance (S2). At the peak point, both the rotation angle of the body and that of the shoulder in high point performance are big as well. In conclusion, it is shown that a performer can make a jump toward the high bar easily with the body straight because the performer can hold the upper part of the body erect early in a descending phase.

• Asian-Australasian Journal of Animal Sciences
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• v.5 no.3
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• pp.469-473
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• 1992

Data on the birth weight, 8 week body weight and ewe body weight of an unselected random mating Romney Marsh sheep flock are analyzed to study the influence of various environmental factors. The average birth weight of lambs was 5.06 kg. Sex of lamb, birth type and dam age contributed significant variation in lamb birth weight (p < 0.05). Males were significantly heavier than females (p < 0.05) and singles were significantly heavier than multiples (p < 0.05) at birth. Birth weight of lamb increased with the progress of dams' age. The overall average 8 week body weight of lambs was 20.84 kg. Effect of birth weight, sex, birth type and dam age was significant on 8 week body weight of lamb. Eight week body weight increased with the increase of lamb birth weight (b=1.285 kg). Ewes' body weight taken before tupping was affected by ewes' age, year of performance and their weight at birth. It was concluded that performance data on lamb birth weight, 8 week body weight and ewe body weight should be corrected for the above relevantly significant environmental factors in any genetic calculation in the United Kingdom Romney March sheep.

• Asian-Australasian Journal of Animal Sciences
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• v.29 no.10
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• pp.1451-1457
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• 2016

A comparative study was performed to investigate the efficacy of KiFAY as a feed additive on performance parameters, thyroid, and pancreatic hormone levels in broilers. Ninety birds (Vencobb 400) were randomly divided into three groups viz., Control (no DL-methionine supplementation), Treatment1 (containing added DL-methionine) and Treatment 2 (containing KiFAY and without DL-methionine supplementation). The performance parameters (weekly body weight, body weight gain, feed intake, and feed consumption ratio) were recorded and calculated during the whole study of 4 weeks. Analyses of insulin and insulin-like growth factor (IGF 1), triiodothyronine (T3), thyroxine (T4) and thyroid stimulating hormone (TSH) were performed at the end of the study. The results show that birds on supplementation of KiFAY performed significantly (p<0.001) better than other treatments. The weekly body weight, body weight gain, feed in-take and feed consumption ratio improved in KiFAY treated birds. The study found an increase in insulin and IGF1 levels (p<0.001) in KiFAY compared with the other treatments. Serum T3, T4, and TSH levels in the Treatment 2 were higher than other treatments (p<0.001). The KiFAY supplementation was able to improve performance with associated responses at a hormonal level in broilers.

• Physical Therapy Korea
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• v.26 no.4
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• pp.20-28
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• 2019

Background: The wall squat exercise has been recommended for strengthening of the lower extremity muscles with maintaining lumbar lordosis. Although squat has been studied to be related to lower extremity extensor strength, the relationship between wall squat and lower extremity extensor strength unclear. Because squat and wall squat are biomechanically different, study on the relationship is needed. Objects: The purpose of this study was to determine the lower extremity extensor strength associated with wall squat performance. Methods: 74 healthy volunteers were recruited to participate in this study. The volunteers were measured hip and knee extensors strength and then performed wall squat exercise for maximum count. Results: We found significant relationships between wall squat performance and hip extensor strength normalized by body weight, knee extensor strength normalized by body weight and the composite value. In a regression analysis, hip extensor strength normalized by body weight explained 29% of the variation in wall squat performance in males and 35% in females. Conclusion: These results demonstrate that hip extensor strength normalized by body weight is critical to wall squat performance in both sexes.

• Asian-Australasian Journal of Animal Sciences
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• v.15 no.10
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• pp.1502-1506
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• 2002

This experiment was conducted to evaluate the effects of the broiler's genotype ($G_t$) and ambient temperature ($T_a$) on performance and core body temperature ($T_core$) of broiler chicks. A factorial arrangement of two $G_t$ (Hubbard and ISA J57 chicks) and two $T_a$ (moderate, $23{\pm}0.5^{\circ}C$ and hot, $33{\pm}0.5^{\circ}C$) were used in this study. Performance data (body weight gain, feed intake and feed:gain ratio) were determined weekly for six weeks. Chicks' $T_core$ was measured using a biotelemetric system between Weeks five and six. Results showed that body weight gain and feed intake were significantly high, and feed:gain ratio was significantly low for Hubbard chicks compared to those of ISA J57 chicks. High $T_a$ significantly reduced weight gain and feed intake. Furthermore, the reduction in body weight gain and feed intake under the hot $T_a$ was more pronounced for Hubbard chicks than those of the ISA J57 chicks resulting in significant $G_t$ by $T_a$ interaction. Chicks grown under moderate $T_a$ had significantly lower $T_core$ than those grown under hot $T_a$. The $T_core$ of the Hubbard chicks was significantly lower than that of the ISA J57 at the moderate $T_a$ while under the hot $T_a$, the magnitude of the change in $T_core$ was more pronounced in Hubbard chicks than that of ISA J57; this resulted in a significant $G_t$ by $T_a$ interaction. The results of this study indicate that chicks with higher potential for growth under thermo-neutral temperature are more susceptible to heat stress than chicks with lower potential for growth. This maybe due, at least in part, to their lower body $T_core$ under moderate temperature and to the lesser ability of these fast growing chicks to regulate their $T_core$ when exposed to heat stress, as was clearly shown on these birds' performance.