• Proceedings of the Korea Contents Association Conference
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• 2016.05a
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• pp.265-266
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• 2016

This study aimed to examine the effects of mental practice on normal persons' balance ability. Thirty subjects that participated in the experiment were randomly assigned to an experimental group of 15 subjects and a control group of 15 subjects. Both the experimental group and the control group underwent balance training conducted in a sitting position on a gym ball for 20 minutes per time, five times per week for four weeks and the experimental group additionally underwent mental practice for 10 minutes before balance training. After the intervention, balance measuring equipment (Good Balance, Metitur, Finland) was used to quantitatively measure balance ability. Significant differences in the post-training gains in variable of Medial-lateral, Index of balance function, Time were observed between the experimental group and the control group (p<0.05). Both Application of mental practice with balance training aimed at improving balance ability is considered to have positive effect.

• Transactions of The Korea Fluid Power Systems Society
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• v.6 no.4
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• pp.24-32
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• 2009

For a design of on/off solenoid actuator for valve actuating, designer must have the experimental knowledge as well as general electromagnetic formulas to design object. It is possible for theoretical knowledge to do the out-line design, but it is impossible to optimal design without experimental knowledge which only can be achieved through many repeated experiments. In addition, in present on/off type solenoid actuator field, the smaller, lightening, lower consumption power, high response time are effected as the most important design factor. So, experimental knowledge is more needed for optimal design of solenoid actuator. In this study, we derived the governing equations for optimal design of on/off solenoid actuator for valve actuating and developed a design program composed electromagnetic theories and experimental parameter values for inexperienced designers. And we proved the propriety of this program by experiments.

• Journal of Internet Computing and Services
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• v.25 no.1
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• pp.109-121
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• 2024

In various manufacturing processes such as textiles and automobiles, when equipment breaks down or stops, the machines do not work, which leads to time and financial losses for the company. Therefore, it is important to detect equipment abnormalities in advance so that equipment failures can be predicted and repaired before they occur. Most equipment failures are caused by bearing failures, which are essential parts of equipment, and detection bearing anomaly is the essence of PHM(Prognostics and Health Management) research. In this paper, we propose a preprocessing algorithm called SWT-SVD, which analyzes vibration signals from bearings and apply it to an anomaly transformer, one of the time series anomaly detection model networks, to implement bearing anomaly detection model. Vibration signals from the bearing manufacturing process contain noise due to the real-time generation of sensor values. To reduce noise in vibration signals, we use the Stationary Wavelet Transform to extract frequency components and perform preprocessing to extract meaningful features through the Singular Value Decomposition algorithm. For experimental validation of the proposed SWT-SVD preprocessing method in the bearing anomaly detection model, we utilize the PHM-2012-Challenge dataset provided by the IEEE PHM Conference. The experimental results demonstrate significant performance with an accuracy of 0.98 and an F1-Score of 0.97. Additionally, to substantiate performance improvement, we conduct a comparative analysis with previous studies, confirming that the proposed preprocessing method outperforms previous preprocessing methods in terms of performance.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.1
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• pp.413-419
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• 2011

Diagnosis X-ray equipment localized at 1950's but it is developed suddenly at 1960's with demand together. Manufacture of Diagnostic X-ray equipment is controled by the KS regulation and the Ministry of Health and Welfare because of hazardous element etc. exposure by radiation. Most of diagnostic X-ray equipment ware single phase and three phase full-wave rectification but from 1980's it transforms it was exchanged in inverter type X-ray equipment. Inverter type X-ray equipment produces approximately 50~80% more average photon intensity then single phase full-wave rectification and the accuracy is high. But from a clinic it dose not use because expensive therefor the efficiency improvement of single phase full-wave rectification is necessary. We produced single phase full-wave rectification X-ray equipment control unit, high tension transformer, filament heating transformer, rectification circuit, high tension cable and others and evaluated efficiency, in result which is excellent compare with Rule of Safety Management and KS regulation.

• Journal of Ecology and Environment
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• v.38 no.3
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• pp.293-305
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• 2015

In order to understand the mechanisms of conversion between different algal dominance, an experiment was performed in a greenhouse from 22 June to 10 July 2011. The experiment included a treatment group subjected to three instances of nutrient enrichment and a control with no nutrient enrichment. The initial water was dominated by Ankistrodesmus of Chlorophyta. The average water temperature at 08:30 h and 14:00 h during the experiment was $31.6^{\circ}C$ and $34.6^{\circ}C$, respectively. The results showed that the total nitrogen (TN), total phosphorus (TP), dissolved total nitrogen (DTN), dissolved total phosphorus (DTP), and soluble reactive phosphorus (SRP) concentrations in the treatment were significantly higher than in the control (P < 0.05). However, the TN/TP and DTN/DTP in the control was higher than in the treatment (P < 0.05). The dominant algae in the control did not change during the experiment, while the dominant algae in the treatment switched to Planktothrix of Cyanophyta on day 9. The chlorophyll a (Chl-a), wet weight of all algae, wet weight of Cyanophyta, and percentage of Cyanophyta in the control were all significantly lower than in the treatment (P < 0.05). Amounts of zooplankton, especially rotifers, were present at the end of the experimental period. The density of rotifers between the control and treatment was not significantly different (P > 0.05), while the copepod density in the treatment was higher than in the control (P < 0.05). We conclude that green algae dominance quickly switches to cyanobacteria dominance after nutrient enrichment in a greenhouse with elevated temperature.

• Journal of Power Electronics
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• v.15 no.3
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• pp.660-669
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• 2015

This paper presents a control scheme with a focus on the combination of phase disposition pulse width modulation (PDPWM) and DC capacitor voltage control for a chopper-cell based modular multilevel converter (MMC) for the purpose of eliminating the time-consuming voltage sorting algorithm and complex voltage balancing regulators. In this paper, the convergence of the DC capacitor voltages within one arm is realized by charging the minimum voltage module and discharging the maximum voltage module during each switching cycle with the assistances of MAX/MIN capacitor voltage detection and PDPWM signals exchanging. The process of voltage balancing control introduces no extra switching commutation, which is helpful in reducing power loss and improving system efficiency. Additionally, the proposed control scheme also possess the merit of a simple executing procedure in application. Simulation and experimental results indicates that the MMC circuit together with the proposed method functions very well in balancing the DC capacitor voltage and improving system efficiency even under transient states.

• The Transactions of the Korean Institute of Power Electronics
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• v.22 no.1
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• pp.82-88
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• 2017

This study proposes a new topology for the performance test of a valve consisting of a modular multilevel converter (MMC)-based static synchronous compensator (STATCOM). The conventional valve performance test equipment requires high-voltage AC source of several kV rating because the number of submodules to be tested in a valve should be at least six or eight. However, the power source of the proposed scheme is DC and not AC source. The DC power source voltage range of the proposed test circuit is from several volts to several tens of volts. Therefore, the size and cost for the performance test equipment can be reduced considerably compared with the conventional method. The proposed scheme satisfies the requirements of the IEC 62927 standard. Simulations are conducted for a valve of 50[MVA] MMC-based STATCOM. Experimental results with a scale-downed setup show the validity of the proposed performance test topology.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.18 no.4
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• pp.472-479
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• 2011

Purpose: The purpose of this study was to develop guidelines for cleaning of enteral nutrition bags by comparing the level of equipment contamination according to cleaning and disinfection methods. Method: This study was a true-experimental study, with 60 cases in total. Twenty cases each were randomly assigned to tepid water, detergent and brush, and disinfectant groups. The period of the experiment was March to April 2010, and enteral nutrition was given for 1 houre, 3 times a day at 7AM, noon, and 7PM for seven days. Enteral nutrition bags were cleaned after each feeding according to assigned cleaning and disinfection method followed by microbial cultures on 4th and 8th day before the 7AM feeding. Results: After 3 days of feeding and cleaning, the level of contamination of bags was not significantly different among the three groups. After seven days, the level of contamination was significantly lower when bags were cleaned with detergent and brush or with disinfectant compared to cleaning with tepid water. Conclusion: In cases where enteral nutrition bags are reused for example, in home care settings, studying findings indicate that cleaning bags using detergent and brush or disinfectant is an effective way to prevent contamination of bags.

• Journal of Advanced Marine Engineering and Technology
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• v.30 no.1
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• pp.42-49
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• 2006

In this research. the diesel cycle was thermodynamically interpreted to evaluate the possibility of high efficiency by converting diesel engines to the high expansion diesel cycle, and general cycle features were analyzed after comparing these two cycles. Based on these analyses. an experimental single cylinder a long stroke with high expansion-diesel engine. of which S/B ratio was more than 3, was manufactured. After evaluating the base engine through basic experiments, a diesel engine was converted into the high expansion diesel engine by establish VCR device and VVT system Accordingly, the high expansion diesel cycle can be implemented when the quantity of intake air is compensated by supercharge and the effective compression ratio is maintained at its initial level through the reduction of the clearance volume. In this case, heat efficiency increased by $5.0\%$ at the same expansion-compression ratio when the apparent compression ratio was 20 and the fuel cut off ratio was 2. As explained above, when the atkinson cycle was used for diesel cycle, heat efficiency was improved. In order to realize high expansion through retarding the intake value closing time, the engine needs to be equipped with variable valve timing equipment, variable compression ratio equipment and supercharged pressure equipment. Then a high expansion diesel cycle engine is realized.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.4
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• pp.415-424
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• 2004

Cooling the electronic equipment is one of the major focal points of the design process and the key to successful product launch. The two-phase loop thermosyphone which is a good candidate among many available options was investigated fur cooling of the high power amplifiers. The system is composed of evaporator which contains 6 parallel cold plates, fan cooled condenser, gas-liquid separator, and interconnecting tubes. Experiments were performed for several refrigerant charging values, hs and as a experiment result, the optimum charging value fur this system was proposed. In order to optimize the system design, the operating cycle pressure and inlet/outlet temperatures of evaporator and condenser are measured and analyzed. The effect of the three parameters such as flow rate and temperature of condenser cooling air, and thermal load on the evaporator are investigated. The lower the operating pressure and the cycle temperatures are also better to prevent the leakage of the system. The system invesigated in this paper can be directly used for cooling of a real unmanned wireless communication station.