• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.4
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• pp.117-122
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• 2018

A large-capacity three-phase system air conditioner recently includes an inverter circuit to reduce power consumption. The inverter circuit uses a DC voltage that comes from DC-link power capacitor with the function of rectifying, which means AC voltage to DC voltage using a diode. An electrolytic capacitor is generally used to satisfy the voltage ripple and current ripple conditions of a DC-link power capacitor used for rectifying. Reducing the capacitance of the capacitor decreases the size, weight, and cost of the circuit. This paper proposes an algorithm to reduce the input ripple current by combining the minimum point estimation phase locked loop (PLL) phase control and the average voltage d axis current control technique. When this algorithm was used, the input ripple current decreased by almost 90%. The current ripple of the DC-link capacitor decreased due to the decrease in input ripple current. The capacitor capacity can be reduced but the electrolytic capacitor has a heat generation problem and life-time limitations because of its large equivalent series resistance (ESR). This paper proposes a method to select a film capacitor considering the current ripple at DC-link stage instead of an electrolytic capacitor. The capacitance was selected considering the voltage limitation, RMS (Root Mean Square) current capacity, and RMS current frequency analysis. A $1680{\mu}F$ electrolytic capacitor can be reduced to a $20{\mu}F$ film capacitor, which has the benefit of size, weight and cost. These results were verified by motor operation.

• Journal of Digital Contents Society
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• v.19 no.8
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• pp.1585-1592
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• 2018

Due to un-balancing weight allocation on the wheelchair the existing wheelchair system are faced with the risk of flipping or falling when a wheelchair goes up to a hill. In to order to be safer during riding the wheelchair, in this paper, we proposed a real-time new solution using the integrated Gyro Sensor and Tilt Sensor for controlling the balance. Because the typical property of wheelchair is for the special user who meets the difficulty in moving on foot the maintain the balance of wheel-chair systems have become important and helpful. In our method, we calculate the seat angle using information from Tilt Sensor. However, due to the law of inertia when a wheelchair is moving there is a deviation in the output value of Tilt Sensor. Therefore, we have to optimize the value of the angle by utilizing the acceleration that is the output of the Gyro Sensor. We took the advantages by using the combination of Gyro and Tilt sensors. Moreover, we also solved the consumption issue of the whole system. Through various experimentations with usage of ZigBee sensor module, the power consumption for the balancing system is reduced significantly.

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.2
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• pp.351-356
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• 2008

Cerebral palsy, a range of non-progressive syndromes of posture and motor impairment, is a common cause of disability in childhood. Self-injurious behavior(SIB) is deliberate harm to the body without suicidal intend, often involving repetitive actions that cause tissue damage. One of the most common orofacial self-injurious behavior is chewing tongue, lip or oral mucosa. This kind of SIB in children is not common in normal children. High occurrence rates are observered in cases of syndromatic, mentally retarded children, and children with congenital disease. Various methods such as behavior modification, behavior control by drugs, body restraints, application of dental appliance, surgery and extraction of teeth have been suggested to control those self-injurious behavior. Using mouthguard as one of dental applainaces is the most conservative and appropriate method in terms of reducing oral self-injurious habits and protection of tissue. This case report describes a child with cerebral palsy who presented with self-injurious ulceration of lip and buccal mucosa. A modified mouthguard was effective in preventing self-injurious oral trauma in a child with cerebral palsy.

• The Journal of Korean Academy of Sensory Integration
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• v.19 no.1
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• pp.54-68
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• 2021

Objective : This study aimed to analyze and classify the task-oriented training methods used to improve the daily lives of children with cerebral palsy. Methods : The search period from January 2008 to August 2020, and the CINAHL, MEDLINE and PubMed was databases were used. A total of 18 studies was selected, and the PICO method was applied to conduct the systematic review. The training methods were then classified according to task, practice, and feedback as strategies to learn or to exercise control based on prior research. Results : Of the selected studies, 13 reported significant results in the area of motor skills, two of which related to Activities of Daily Living. Discrete and closed were the most common forms of task, and the most used types of practice were whole, part, and blocked, in that order. Finally, feedback was not specifically provided in most studies, followed by extrinsic feedback. Conclusion : Based on this review, task-oriented training for children with cerebral palsy can be made more effective in clinical practice in the future through the systematic selection of techniques that promote exercise control and the presentation of specific methods.

• Journal of Practical Agriculture & Fisheries Research
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• v.17 no.1
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• pp.57-71
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• 2015

This study was conducted to develop the fertigation system with a peristaltic hose pump and brushless DC motor. The fertigation system was consisted of sensor, main controller, motor control unit, peristaltic pump, water supply pump, control panel, and filter. The peristaltic pump discharges liquid by squeezing the tube with rollers. Rollers attached to the external circumference of the rotor compresses the flexible tube. The fluid is contained within a flexible tube fitted inside a circular pump casing. The developed fertigation system has no mixing tank but instead injects directly a concentrated nutrient solution into a water supply pipe. The revolution speed of the peristaltic pump is controlled by PWM (Pulse width modulation) method. When the revolution speed of the peristaltic pump was 300rpm, the flow rate of the 3.2, 4.8, 6.3mm diameter tube was 202, 530, 857mL/min, respectively. As increasing revolution speed, the flow rate of the peristaltic pump linearly increased. As the inner diameter of a tube larger, a slope of graph is more steep. Flow rate of three roller was more than that of four roller. Flow rate of a norprene tube with good restoring force was more than that of a pharmed tube. As EC sensor probe was installed in direct piping in comparison with bypass piping showed good performance. After starting the system, it took 16~17 seconds to stabilize EC. The maximum value of EC was 1.44~1.7dS/m at a setting value of 1.4dS/m. The developed fertigation system showed ±0.06dS/m deviation from the setting value of EC. In field test, Cucumber plants generally showed good growth. From these findings, this fertigation system can be appropriately suitable for fertigation culture for crops.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.48 no.4
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• pp.63-70
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• 2011

In this paper, we proposed a method for estimating energy expenditure using the unfixed axis of the accelerometer. Most studies adopted waist-placement because of the fact that the waist is close to the center of mass of a whole human body. But we adopted pocket-placement, which is capable of using unfixed axis of sensor, that is more convenient than conventional methods. To evaluate the proposed method, 28 male subjects performed walking and running on a motor driven treadmill. All of subject put on the indirect calorimeter and fixed accelerometer, then data were simultaneously measured during exercise. The regression analysis was performed using the test group(n=20) and the regression equation was applied to the control group(n=8). A strong linear relationship between energy expenditure and unfixed accelerometer signal was found. Futhermore, the coefficient of determination was significantly reliable($R^2$=0.98) and showed zero of p-value. The error of energy expenditure estimation between indirect calorimeter and two types of accelerometer was 15.0%(fixed) and 17.0%(unfixed) respectively. These results show the possibilities that the unfixed accelerometer can be used in estimating the energy expenditure during exercise.

• Journal of Biomedical Engineering Research
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• v.25 no.6
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• pp.479-487
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• 2004

Biopotential signals have been used as command in systems using electrical stimulation of motor nerves to restore movement after an injury to the central nervous system (CNS). In order to use the voluntary EMG (electromyography) among the biopotentials as a control signal for the electrical stimulation of the same muscle for CNS injury patients, it is necessary to remove M-wave of having high magnitude from raw data. We designed an optimal filter for removing the M-wave and preserving the voluntary EMG and showed that the optimal filter is eigen filter. We also proved that the previous method using the prediction error filter(PEF) is a suboptimal filtering in the sense of preserving the voluntary EMG. On basis of the data obtained from a model for M-wave and voluntary EMG and from actual CNS injury patients, with false-positive rate analysis, the proposed adaptive filter showed a very promising performance in comparison with previous method.

• Tuberculosis and Respiratory Diseases
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• v.43 no.4
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• pp.590-599
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• 1996

Background : Bronchial artery embolization has been established as an effective means to control hemoptysis, especially in patients with decreased pulmonary function and those with advanced chronic obstructive pulmonary disease. We evaluated the effect of arterial embolization in immediate control of massive hemoptysis and investigated the clinical and angiographic characteristics and the course of patients with reccurrent hemoptysis after initial succeseful embolization. Another purpose of this study was to find predictive that cause rebleeding after bronchial artery embolization. Method : We reviewed 47 cases that underwent bronchial artery embolization for the management of massive hemoptysis, retrospectively. We analyzed angiographic findings in all cases before bronchial artery embolization and also reviewed the angiographic findings of patients that underwent additional bronchial artery embolization for the control of reccurrent hemoptysis to find the clauses of rebleeding. Results : 1) Underlying causes of hemoptysis were pulmonary tuberculosis(n=35), bronchiectasis(n=5), aspergilloma(n=2), lung cancer(n=2), pulmonary A-V malformation(n=1), and unknown cases(n=2). 2) Overal immediate success rate was 94%(n=44), an6 recurrence rate was 40%(n=19). 3) The prognostic factors such as bilaterality, systemic-pulmonary artery shunt, multiple feeding arteries and degree of neovascularity were not statistically correlated with rebleeding tendency (p value>0.05). 4) At additional bronchial artery embolization, Revealed recannalization of previous embolized arteries were 14/18cases(78%) and the presence of new deeding arteries was 8/18cases(44%). 5) The complications(31cases, 66%) such as fever, chest pain, cough, voiding difficulty, paralytic ileus, motor and sensory change of lower extremity, atelectasis and splenic infarction were occured. Conclusion : Recannalization of previous embolized arteries is the major cause of recurrence after bronchial artery embolization. Despite high recurrence rate of hemoptysis, bronchial artery embolization for management of massive hemoptysis is a effective and saute procedure in immediate bleeding control.

• Journal of Chest Surgery
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• v.41 no.4
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• pp.405-416
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• 2008

Background: Spinal cord ischemic injury during thoracic and thoracoabdominal aortic surgeries remains a potentially devastating outcome despite using various methods of protection. Neuronal voltage-dependent sodium channel antagonists are known to provide neuroprotection in cerebral ischemic models. This study was designed to compare the neuroprotective effects of phenytoin with those of hypothermia in a rabbit model of spinal cord ischemia. Material and Method: Spinal cord ischemia was induced in New Zealand white rabbits by means of infrarenal aortic cross clamping for 25 minutes. Four groups of 8 animals each were studied. The control group and the hypothermia group received retrograde infusion of saline only ($22^{\circ}C$, 2 mL/min); the normothermic phenytoin group and the hypothermicphenytoin group received retrograde infusion of 100 mg of phenytoin at different rectal temperatures ($39^{\circ}C$ and $37^{\circ}C$, respectively) during the ischemic period. The neurologic function was assessed at 24 and 72 hours after the operation with using the modified Tarlov criteria. The spinal cords were harvested after the final neurologic examination for histopathological examination to objectively quantify the amount of neuronal damage. Result: No major adverse effects were observed with the retrograde phenytoin infusion during the aortic ischemic period. All the control rabbits became severely paraplegic, Both the phenytoin group and the hypothermia group had a better neurological status than did the control group (p < 0.05). The typical morphological changes that are characteristic of neuronal necrosis in the gray matter of the control animals were demonstrated by means of the histopathological examination, whereas phenytoin or hypothermia prevented or attenuated these necrotic phenomena (p < 0.05). The number of motor neuron cells positive for TUNEL staining was significantly reduced, to a similar extent, in the rabbits treated with phenytoin or hypothermia. Phenytoin and hypothermia had some additive neuroprotective effect, but there was no statistical significance between the two on the neurological and histopathological analysis. Conclusion: The neurological and histopathological analysis consistently demonstrated that both phenytoin and hypothermia may afford significant spinal cord protection to a similar extent during spinal cord ischemia in rabbits, although no significant additive effects were noticed.

• KIPS Transactions on Computer and Communication Systems
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• v.9 no.11
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• pp.265-272
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• 2020

In the research of brain computer interface (BCI) technology, one of the big problems encountered is how to deal with some people as called the BCI-illiteracy group who could not control the BCI system. To approach this problem efficiently, we investigated a kind of spectral EEG characteristics in the prior resting state in association with BCI performance in the following BCI tasks. First, spectral powers of EEG signals in the resting state with both eyes-open and eyes-closed conditions were respectively extracted. Second, a convolution neural network (CNN) based binary classifier discriminated the binary motor imagery intention in the BCI task. Both the linear correlation and binary prediction methods confirmed that the spectral EEG characteristics in the prior resting state were highly related to the BCI performance in the following BCI task. Linear regression analysis demonstrated that the relative ratio of the 13 Hz below and above the spectral power in the resting state with only eyes-open, not eyes-closed condition, were significantly correlated with the quantified metrics of the BCI performance (r=0.544). A binary classifier based on the linear regression with L1 regularization method was able to discriminate the high-performance group and low-performance group in the following BCI task by using the spectral-based EEG features in the precedent resting state (AUC=0.817). These results strongly support that the spectral EEG characteristics in the frontal regions during the resting state with eyes-open condition should be used as a good predictor of the following BCI task performance.