• Tribology and Lubricants
• /
• v.34 no.6
• /
• pp.235-240
• /
• 2018

Superlubricity refers to the lubrication phenomenon that occurs when the friction coefficient is lower than 0.01. In recent years, this phenomenon has received a significant amount of attention because it can greatly contribute to the reduction of economic and environmental losses caused by friction and wear. In the case of acid lubricants, only ceramic materials can be used for superlubricity, and it takes a long running-in period to enter the superlubricity regime. In this work, we investigated the superlubricity effect of vitreous enamel coating on SUS304. We also examined the running-in period of vitreous enamel coating under phosphoric acid lubricant condition with respect to surface treatments. Drying and polishing methods were used to treat the vitreous enamel coating on the specimen. The friction experimental results revealed that superlubricity could be achieved with vitreous enamel coating. It was also found that the drying and polishing methods can significantly reduce the running-in period and improve the wear properties of vitreous enamel coating. In particular, the polishing method shortened the running-in period by approximately 99% and reduced the wear rate by approximately 99%, compared to nontreated vitreous enamel coating.

• Journal of Broadcast Engineering
• /
• v.20 no.6
• /
• pp.950-962
• /
• 2015

This paper analyzes the effect of the number of viewers and the number of running screens in the theater, genres of the movies and holdback period on the number of purchases movie VOD contents. In this paper, we deals with the 169 movies VOD consumption data which the digital cable TV subscribers purchased during the third quarter of 2013. As a result of the research, the average number of VOD purchases per each movie is 2,540. Regression analysis proves that the number of running screens and the holdback period are statistically playing a role of significance in movie VOD purchases. But the number of viewers in the theaters is not of significance. By genres, the result is shown as in this order: SF/fantasy 8,401 > dramas 4,011 > comedies 2,011 > action 1,789 > animation 1,138 > love story/melo 1,119 > horror/thriller 770 > erotic movies 636.

• Journal of Photoscience
• /
• v.9 no.2
• /
• pp.9-12
• /
• 2002

Circadian rhythms can be seen in a variety of physiological functions in insects. Light is a powerful zeitgeber not only synchronizing but also modulating the rhythm to adjust insect's temporal structure to seasonal changes in the environmental cycle. There are two general effects of the length of light phase within 24 hr light cycles on the circadian rhythms, i.e., the modulation of free-running period and the waveform. Since the photoperiodic modulation of the free-running period is induced even in the clock mutant flies, per$\^$s/, the free-running period is not fully determined genetically. In crickets, the ratio of activity (a) and rest phase (p) under the constant darkness (DD) is clearly dependent on the photoperiod under which they have been kept. When experienced the longer photoperiod it becomes smaller. The magnitude of change in a/p-ratio is dependent on the number of cycles they experienced. The neuronal activity of the optic lobe in DD shows the a/p-ratio changing with the preceding photoperiod. These data suggest that a single circadian pacemaker stores and maintains the photoperiodic information and that there is a system that accumulates the effects of single photoperiod to cause greater effects.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
• /
• v.7 no.1
• /
• pp.59-64
• /
• 2011

Feasibility study on energy saving system by utilizing exhausted heat from subway, which is one of the unused energy, was carried out. General heat source system using absorption chiller-heater was used for comparing to the energy saving system, and payback period method using initial cost and running cost of two systems, was used to perform economic estimation. Payback period was about ten years, and this period might be shortened if nation's economic support enact.

• Proceedings of the KSME Conference
• /
• 2008.11a
• /
• pp.882-887
• /
• 2008

In this paper, the dependency of energy efficiency on the walking/running pattern and the walking/running period is analyzed though simulations of walk, trot and gallop. A quadruped animal has its own original features in the walking pattern and the walking period for adaptation to the environment. The robot model used in the simulations has three active joints and one passive spring-loaded joint at each leg, which is based on the actual quadruped robot, HUNTER (Hanyang UNiversity TEtrapod Robot), developed in the lab. Also included is the dependency of energy efficiency on the walking period in trot.

• Physical Therapy Rehabilitation Science
• /
• v.11 no.1
• /
• pp.58-65
• /
• 2022

Objective: The purpose of this study was to investigate the effect of visual feedback bicycle training on running performance, maximal oxygen uptake and quadriceps muscle strength. Design: A randomized controlled trial. Methods: Fifteen healthy adult men with no musculoskeletal or nervous system disease and capable of bicycle training were included. After the pretest, subjects were randomly assigned to visual feedback bicycle training group and general fixed bicycle training group. Both groups were trained two times a week for three weeks, each week for a fixed time and number of repetitions, followed by a six week washout period and then crossing the training method. visual feedback bicycle training provides visual feedback of heart rate in real time using a monitor and a heart rate meter during bicycle training, and general fixed bicycle training performed general bicycle training without visual feedback. After training, each item was measured using a wearable technology, gas analyzer, isokinetic equipment. Results: The results of this study was significant differences in running performance, maximal oxygen uptake and quadriceps muscle strength in visual feedback bicycle training group (p<0.05). The differential effect was found between visual feedback bicycle training group and general fixed bicycle training group in running performance, maximal oxygen uptake, and quadriceps muscle strength (p<0.05). Conclusions: This study suggested that that visual feedback bicycle training can be applied as a useful training method to improve running performance, maximal oxygen uptake and quadriceps muscle strength.

• The Korean Journal of Physiology
• /
• v.11 no.1
• /
• pp.33-36
• /
• 1977

The object of the present study is to examine the effect of physical training during early growth of life on body weight gain and physical performance. Early weaned (2 weeks after birth) male mice were divided into control and training group-and experimental period was divided into growing period (from 1st week to 6th weeks after weaning) and adult period (from 7th weeks to 9th weeks after weaning). Physical training was. given on a small animal treadmill with a speed of 34.3m/min and $19^{\circ}C$ slope and both groups of body weight gain and maximal running time on the treadmill were determined. The results obtained are summarized as follows; 1. Body weight gain was lesser in training group than control group and the difference was. statistically significant at 1, 2.5, 5.7 weeks of training period. 2. Maximal running time of training group was found to be longer than that of control group at 6th (p<0.01), 8th (p<0.001) and 9th weeks. (p<0.01). From the above results, it may be concluded that if physical training is started in early growth of life, there might be an improvement of physical performance.

• Journal of Nutrition and Health
• /
• v.33 no.8
• /
• pp.794-801
• /
• 2000

The purpose of this study is to determine the effects of the aerobic exercise type on macronutrient self-selection. Male Sprague-Dawley rats were placed on a macronutrient self-selection diet for 4 weeks. For this purpose, mixed feeds were prescribed for the rats while they were forced to swim and run for 4 weeks. Animals were either swimming exercise or treadmill running exercised at 20m/min(60min/day). Cumulative daily energy and macronutrient intake were determined during this period. The running exercise group gained weight much more than the control group, while the swimming exercise group lost weight less than the control group. Such findings suggests that the former group took more feed. On the other hand, the dietary efficiency of the control group was higher, which implies that no physical exercise would result in a higher dietary efficiency. And there was significant difference of total dietary and calorie intakes among the three groups, Although insignificant in statistical means, it was found that the running group took feed most, which is attributable to the homeostasis requiring the supplementation of the calorie lost by exercise. Also, the running exercise group took the protein and carbohydrate most. while the control group took fat most. The decrease of fat intake by the running exercise group suggests the possibility that the in-body enzymes should adapt themselves to the changing in-body condition caused by the endurance exercise. In contrast, it is conceived that the more intake of the carbohydrate may be attributable to the need of supplementing the nutrient lost by the endurance exercise. As discussed above, the endurance exercise group took carbohydrate and protein and less fat than control group. In particular, it was found that the amount of feed intakes was affected much by types, intensity and duration of the exercises. All in all, such findings would apply to human beings. Now can increase the intakes of carbohydrate and decrease the intake of fat through an effective running exercise program and thereby, change our dietary patterns to the benefit of our body and simultaneously, prevent and adult\\`s diseases by decreasing the in % body fat level.(Korean J Nutrition 33(8) : 794-801, 2000)

• Wind and Structures
• /
• v.11 no.2
• /
• pp.137-152
• /
• 2008

This paper discusses engineering aspects of the rear-flank downdraft that was recorded near Lubbock, Texas on 4 June 2002, and produced a gust wind speed nearly equal to the design value (50-year return period) for the region. The general characteristics of the storm, and the decomposition of the time histories into deterministic 'running mean' and random turbulence components are discussed. The fluctuating wind speeds generated by the event can be represented as a dominant low-frequency 'running mean' with superimposed random turbulence of higher frequencies. Spectral and correlation characteristics of the residual turbulence are found to be similar to those of high-frequency turbulence in boundary-layer winds. However, the low-frequency components in the running-mean wind speeds are spatially homogeneous, in contrast to the low-frequency turbulence found in synoptic boundary-layer winds. With respect to transmission line design, this results in significantly higher 'span reduction factors'.

• Tribology and Lubricants
• /
• v.22 no.3
• /
• pp.149-154
• /
• 2006

This paper presents the braking friction and wears on the rubbing surfaces of a friction pad-disk brake. In this study, four friction disk specimens are sampled from unused and used disks in which are taken from the disk brake system when the friction induced vibration and noise problems have been occurred during a braking period at a running period of 10,000 km, 20,000 km, and 30,000 km in random. The experimental results indicate that the tribological characteristics of an unused disk brake shows equal and stable as a friction coefficient and temperature distributions during a braking friction/wear test period including a total friction mode from the start to running periods. But the used disk brake shows unstable and uneven friction modes between an outside and inside rubbing surfaces of a disk brake in terms of a friction coefficient and wears. This may lead to a friction induced friction vibration and noise problems of a used disk brake.