• Journal of the Korean Chemical Society
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• v.61 no.4
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• pp.143-150
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• 2017

Countercurrent oxidation process (COP) was developed and evaluated for treatment of highly concentrated PCB containing insulating oil. The PCB content in insulating oil taken from Haksanmetal company was found to be 1,512 ppm. The COP utilizes a self-sustained flame which propagates itself in a direction counter to the oxygen flow. The flame removes PCBs adsorbed in activated carbon and, at the same time, regenerates activated carbon. The flame temperature was determined from both mass loss of activated carbon and the relative ratio of CO and $CO_2$ exhausted during COP, and showed that its temperature lied in the range of $650-850^{\circ}C$. Removal efficiency of PCBs was achieved above 99.99% for 5% of insulating oil loaded activated carbon with 1 COP in weight ratio. Also, the same removal efficiency was acquired for 60% of insulating oil loaded activated carbon with three consecutive COP. In addition, specific surface area of activated carbon during COP was recovered to almost similar value of virgin activated carbon. It proved that the COP was much effective in removing high concentration of PCBs in insulating oil easily and affordably.

• Proceedings of the Botanical Society of Korea Conference
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• 2000.04a
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• pp.23-23
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• 2000

• Journal of the Korean Applied Science and Technology
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• v.37 no.2
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• pp.224-231
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• 2020

The purpose of this study was to analyze the effect of ankle joint taping treatment on lower extremity joint and center of pressure(COP) factors during the Uchi-mata. Twenty college judo athletes (age, 20.9 ± 0.8 years; height, 168.6 ± 7.4cm; weight, 73.5 ± 11.6kg; body mass index, 25.7 ± 2.6kg/㎡) participated, and two types before and after ankle joint taping treatment when the during the Uchi-mata was exhibited under conditions, the angle and COP factors of the support leg joints were analyzed to show the following results. At the time of E2 (t = 2.411, p = .027) E4 (t = 2.388, p = .029), the ankle joint angle was statistically less after the treatment than before the taping treatment, and E2 (t = -2.343, p = .032) At E3 (t = -4.531, p = .000), the angle of the hip joint was statistically large. And after the ankle joint taping treatment, the medial/lateral COP movement after the ankle joint taping treatment was statistically large in the P3 phase of throwing the opponent (t = 2.670, p = .016), and the anterior/posterior COP movement showed a statistically small number in the P1 phase where the opponent was tilted (t = 2.846, p = .011). Therefore, it was suggested that judo athletes who use thighs as a special technique should be used considering the movement function of the support joint and the range of movement of the COP caused by tapping of the ankle joint.

• Journal of Energy Engineering
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• v.24 no.4
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• pp.124-129
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• 2015

An experimental study was performed estimating COP(Coefficient of Performance) of air-conditioning cycle using inverter scroll compressor with and without $Al_2O_3$ nano particle. All experiments were done for various compressor speeds from 1000~4000 rpm and used the inverter controller called CANDY to change the compressor rpm. The air-conditioning cycle components in the apparatus were used as same with components of YF hybrid car. To estimate the COP, this study measured the temperature and pressure at inlets and outlets of compressor, condenser, and evaporator. And also measured the compressor input power using Powermeter. Through the experiments, the maximum error to estimate COP was shown about ${\pm}6.09%$ at 3500rpm. The COP of refrigeration cycle with $Al_2O_3$ nano-particle was similar with that of the base cycle without nano-particle between 1000~3000 rpm of the compressor speed. But, This study showed that the COP of the cycle with $Al_2O_3$ over 3000 rpm of the compressor speed was higher than that of the base cycle due to the higher heat transfer rate increased in the evaporator from the higher oil flow rate inside the cycle as well known. Those results can be used the basic and fundamental data to design the air-conditioning cycle using inverter scroll compressor with $Al_2O_3$ nano particle.

• Korean Journal of Applied Biomechanics
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• v.22 no.1
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• pp.55-63
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• 2012

The purpose of this study was to investigate the balance differences between skilled players and less-skilled players during Hakdariseogi motion of Keumgang Poomsae in Taekwondo. To achieve the study goal, total of 10 Taekwondo athletes; 5 skilled players(S, body mass: $67.0{\pm}5.7$ kg, height: $174.0{\pm}4.8$ cm, age: $20.0{\pm}2.0$ yrs) and 5 less-skilled players(LS, body mass: $73.0{\pm}4.9$ kg, height: $176.4{\pm}6.1$ cm, age: $20.8{\pm}1.3$ yrs) participated in this study. A three-dimensional motion analysis with 8 infrared cameras and one force plate whose sampling frequency as 30 Hz and 300 Hz, respectively, were performed. Participants' motion were divided into three phases which were preparation phase(P1), performing phase(P2) and maintaining phase(P3). The range and velocities of COP, the range and RMS of ground reaction torque and displacement between COM and center of BOS of each phase were computed. In this study, at P1 and P3 which were double and single stance, respectively, the range and M-L velocities of COP revealed significantly higher in LS compared with those of S(p<.05). At P2 which was single stance, LS indicated significantly higher in range of COP and ground reaction torque, and M-L velocities of COP than those of S(p<.05). The significantly shorter displacement between COM and center of BOS, however, was found in LS compared with that of S(p<.05). The results from our study indicated that S revealed more stable performance and a better posture control ability during performing Hakdariseogi motion.

• Journal of Biomedical Engineering Research
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• v.28 no.5
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• pp.628-635
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• 2007

We studied the effect of vibratory stimulations of different leg muscles, tibialis anterior(TA) and triceps surae(TS), and plantar zones in ten healthy subjects during 1) quiet standing, 2) forward lean of body, 3) backward lean of body, 4) right lean of body, and 5) left lean of body. The experiments were performed on the force platform. The effect of vibration were measured by monitoring the area of COP(Center of pressure) sway. The subjects wore a vibratory stimulation system on foot and ankles and were given the instruction not to resist against the applied perturbations. The results show that all vibratory stimulations to lower limb muscles and plantar zones reduced the COP sway area. This reduction of the COP sway area occurred also in partial vibratory stimulations during quiet standing. In forward lean of body, vibratory stimulations to TA reduced the COP sway area. During backward lean of body, vibratory stimulations to TS reduced the COP sway area. When the subject was tilted right, vibratory stimulations to left plantar zone reduced the COP sway area. During left lean of body, vibratory stimulations to right plantar zone reduced the COP sway area. Thus, the influence of vibratory stimulations to leg muscle and plantar zones differed significantly depending on the lean of body. We suggest that the vibration stimuli from leg muscles and plantar zones could be selectively used to help maintaining postural balance stable.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.8
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• pp.1789-1794
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• 2009

In the present study, the cooling performance characteristics on environment changes of A/C applied fin-tube and PF heat exchangers were experimentally investigated. Capacity and COP on an air velocity, an indoor/outdoor temperature and an indoor/outdoor relative humidity were obtained. Fin types of PF heat exchanger were a triangler and squarer form. The experimental data for the three kinds of heat exchangers were measured using the air-enthalpy calorimeter. Performance of PF A/C was more excellent than that of a fin-tube A/C. Also, the performance of PF-2 A/C with the squarer fin was more excellent than that of PF-1 A/C with the triangler fin. As the air velocity, the indoor temperature and the indoor relative humidity increase, capacity and COP increase. And as outdoor temperature increases, capacity and COP decrease. But, the performance change on the outdoor relative humidity was insignificant.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.7
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• pp.828-833
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• 2014

In this paper, the performance characteristics for newly developed ejector refrigeration system, which is that the part of saturated vapor from liquid-vapor separator after ejector expansion process is entrained in ejector, and the saturated liquid flows in the evaporator and compressed with the rest of vapor in separator, is studied. The reasons of the performance improvement of refrigeration system are that the refrigeration capacity is increased due to quality reduction after iso-entropic expansion process by ejector and the compression work is reduced because of the relatively high pressure of vapor refrigerant before compression process. The comparison results of the ejector system entraining expansion gases with the present residential freezer show that the COP increases to 27.8% maximum in case of the pressure drop to 65% of high pressure of freezer, and to 40.1% for 75% pressure drop of refrigerant R401A. The COP improvement rate with 20%~60% pressure lift in diffuser of ejector is only 2.6%~3%.

• Journal of Korean Foot and Ankle Society
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• v.24 no.1
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• pp.14-18
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• 2020

Purpose: Chronic ankle instability is a very common abnormality of the ankle, but there is still controversy regarding its evaluation criteria. The stress view has difficulties in reflecting the patient's symptoms and treatment progress. Therefore, this study examined the relationship between the center of pressure (COP) measured by a pedobarograph and the symptoms of the patient. Materials and Methods: Thirty patients with chronic ankle instability from February to August 2018 were included. Each patient was surveyed with the foot and ankle outcome score (FAOS). The COP was measured with a foot pressure scanner, and the travel distance and ellipse area of the COP were calculated. Each patient was measured on one foot and on two feet with his or her eyes closed and open. The relationship between the COP measurement and FAOS score was analyzed using the Pearson correlation coefficient. Results: The participants were consisted of 21 male and nine female, with a mean age of 30 years, mean weight of 72 kg, and mean foot size of 259 mm. With the eyes open, the correlation coefficient between the FAOS and travel distance of the affected side was -0.394 (p<0.05) and that between the FAOS and the ellipse area of the affected side was -0.425 (p<0.05). On the other hand, no significant correlations were found between the travel distance and ellipse area of the affected side when patients closed their eyes. Conclusion: Measurement of the COP using foot pressure scanner could evaluate objectively patients with chronic ankle instability, with measurements in patients with their eyes open being more significant. Based on the findings of this study, an analysis of the COP with the patients with their eyes open and standing on one foot may help determine the management strategy and assess the progress of the patients.

• Journal of Institute of Convergence Technology
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• v.1 no.2
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• pp.29-32
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• 2011

In this paper, we will introduce the overview of new project dealing how to increase of refrigeration cycle COP using nano-fluids, CuO, TiO2, Al2O3, that are used on similar previous studies. Recently many studies were performed to show the effect of nano-fluids at refrigeration cycle. But, the reason was not cleared yet. In general, the flow phenomena at the evaporator were guessed to be mixed with the partial pool boiling condition and the flow boiling condition from the previous results not published yet. So, we hope that the COP increase of refrigeration cycle will be verified and showed through this project.