• Proceedings of the KIPE Conference
• /
• 2019.07a
• /
• pp.50-52
• /
• 2019

Dynamic resistance equalization is a viable technique to balance SOC of cells in a parallel-connected battery configuration due to high equalization performance, simplicity and low-cost. However, an inappropriate design of the equalization resistor can degrade the equalization performance and increase the power loss. This paper proposes an optimization process to design the equalization resistors to minimize power loss and equalization error. The simulation results show that the optimally designed resistor significantly enhance the performance in comparison with the conventional fixed-resistor equalization.

• Journal of Korean Society of Environmental Engineers
• /
• v.32 no.4
• /
• pp.357-362
• /
• 2010

Electricity can be directly generated from organic matter even wastewaters using a microbial fuel cell. To achieve high power in MFCs, finding factors decreasing activation and Ohmic losses is very important. In this study we determined activation loss at the anode and cathode and Ohmic loss using the current interruption technique in a H-type MFC. Activation loss at the cathode was four times higher that that of anode activation loss even if pt-coated carbon (0.5 $mg/cm^2$;10%Pt) was used as the cathode. Ohmic loss determined using current interruption technique (1146 ${\Omega}$) was almost same as the internal resistance (1167 ${\Omega}$) measured using AC impedance. The sum of activation losses at the anode and cathode was the same as the value of activation loss of the cell.

• The Korean Journal of Pain
• /
• v.22 no.2
• /
• pp.163-166
• /
• 2009

The superiority of air versus saline for identifying the epidural space remains unestablished. Epidural anesthesia using a loss of resistance technique (LORT) with air is associated with increasing complications of dural puncture-induced headaches and neurological and hemodynamic changes. Here, we described a case of pneumocephalus with a large amount of air that was accompanied by severe headache and nuchal and chest pain occurring after epidural block using LORT with air for combined spinal-epidural anesthesia.

• The Korean Journal of Pain
• /
• v.10 no.2
• /
• pp.254-257
• /
• 1997

Ganglion impar lies immediately anterior to the sacrococcygeal junction and blockade of the ganglion is used to treat anorectal and perineal pain. Although the technique introduced by Plancarte et at is widely practised, the bent needle is sometimes difficult to position precisely and patients find the procedure painful. We modified this approach of block of ganglion impar by positioning the needle into the sacrococcygeal junction and using the loss of resistance technique. With the patient in the lateral position, a skin wheal was raised at 1-1.5cm below the sacral hiatus. Twenty-three gauge short needle was directly placed into the sacrococcygeal junction with aid of fluoroscopic guidance. From 1 cm behind the anterior margin of the vertebral body in lateral view, we used the loss of resistance technique to confirm the retroperitoneal space. We found this modified approach easier to perform during six blocks for three patients with anorectal or perineal pain. Our modified approach through the sacrococcygeal junction may provide opportunity for wider administration of this procedure because of its simple technique, reduced pain during procedure and decreased risk of infection.

• Proceedings of the KIPE Conference
• /
• 2018.11a
• /
• pp.36-38
• /
• 2018

As the battery capacity requirement increases, battery cells are connected in a parallel configuration. However, the sharing current of each battery cell becomes unequal due to the imbalance between cell's impedance which results the mismatched states of charge (SOC). The conventional fixed-resistance balancing methods have a limitation in battery equalization performance and system efficiency. This paper proposes a battery equalization method based on dynamic resistance technique, which can improve equalization performance and reduce the loss dissipation. Based on the SOC rate of parallel connected battery cells, the switches in the equalization circuit are controlled to change the equivalent series impedance of the parallel branch, which regulates the current flow to maximize SOC utilization. To verify the method, operations of 4 parallel-connected 18650 Li-ion battery cells with 3.7V-2.6Ah individually are simulated on Matlab/Simulink. The results show that the SOCs are balanced within 1% difference with less power dissipation over the conventional method.

• The Korean Journal of Pain
• /
• v.23 no.4
• /
• pp.247-253
• /
• 2010

Background: Epidural anesthesia is widely used to provide pain relief, whether for surgical anesthesia, postoperative analgesia, treatment of chronic pain, or to facilitate painless childbirth. In many cases, however, the epidural catheter is inserted blindly and the indwelling catheter position is almost always uncertain. Methods: In this study, the loss-of-resistance technique was used and an imaging agent was injected through the indwelling epidural anesthesia catheter to confirm the position of its tip and examine the migration rate. Study subjects were patients scheduled to undergo surgery using general anesthesia combined with epidural anesthesia. Placement of the epidural catheter was confirmed postoperatively by injection of an imaging agent and X-ray imaging. Results: The indwelling epidural catheter was placed between upper thoracic vertebrae (n = 83; incorrect placement, n = 5), lower thoracic vertebrae (n = 123; incorrect placement, n = 5), and lower thoracic vertebra-lumbar vertebra (n = 46; incorrect placement, n = 7). In this study, a relatively high frequency of incorrectly placed epidural catheters using the loss-of-resistance technique was observed, and it was found that incorrect catheter placement resulted in inadequate analgesia during surgery. Conclusions: Although the loss-of-resistance technique is easy and convenient as a method for epidural catheter placement, it frequently results in inadequate placement of epidural catheters. Care should be taken when performing this procedure.

• The Korean Journal of Pain
• /
• v.24 no.1
• /
• pp.44-47
• /
• 2011

We report a case of failed epidural anesthesia despite successful identification of the epidural space, loss of resistance technique, hanging drop method and drip infusion. This case evaluated the use of computed tomography to confirm epidural catheter position, which showed the catheter accidentally positioned at the T2 lamina. Because epidural anesthesia can even after successful procedure using standardized techniques such as loss of resistance, we recommend performing the procedure under fluoroscopic guidance to improve success rate and patient safety.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.63 no.2
• /
• pp.107-112
• /
• 2014

To cope with the ever increasing electric power demands in metropolitan areas, a greater underground cable transmission capacity is required. In general, it must be determined whether the temperature in the tunnel maintains the maximum allowable temperature. In order to improve this point, it is used to the loss factor. But, for economic cooling, it is problem to use such loss factor in this country. In this study, based on the load factor in this country, technique for calculating the loss factor has been presents. The suggested method has been tested in a sample section using the computer and the results have shown the usefullness of the suggested method.

• Journal of the Korean Society of Industry Convergence
• /
• v.23 no.5
• /
• pp.853-863
• /
• 2020

As the battery ages, the internal resistance of the battery increases, so the loss due to the internal resistance increases at the same charging current, causing the battery temperature to rise, which further accelerates battery aging. Therefore, it is necessary to optimize the charging conditions according to the aging of the battery or the current charge amount, and to accurately estimate this, estimation of the parameters of the equivalent circuit is most important. This paper proposes a new measurement technique that can measure the internal resistance of a battery by analyzing a specific high frequency voltage and current applied to the battery. In addition, in order to test the validity of the proposed measurement technique, the current charging amount was estimated based on the measured internal resistance, and the terminal voltage of the constant current charging mode was automatically set and operated. As a result, good results were obtained regardless of the battery voltage. If this equipment is installed in the charging device, it is believed that it will be of great help in the stability management of the aging reusable battery.

• Journal of the Korean Wood Science and Technology
• /
• v.49 no.1
• /
• pp.82-92
• /
• 2021

Nakdong technique is an unfamiliar scorching treatment using an iron heated in a kiln over 1000℃. It is a typical convention in Asian countries to treat Nakdong on the surface of paulownia species. The scorching treatment changes the surface characteristics as well as the color of the wood. This study focused on the effects of functional features such as water resistance, anti-mold, anti-termite, and sound improvement because this treatment is usually used on paulownia wood-bodied musical instruments surface. It took 28'57" for Nakdong-iron treated surface to absorb a droplet of water. The absorbance time of iron treated surface was longer than that of torch treated one. There was no noticeable effect on the anti-mold test. On the anti-termite test, there was nearly 3% more mean mass loss on the torch samples than controlled and iron treated ones. In examining the sound radiation coefficient before and after Nakdong treatment, the Nakdong-iron treated surface showed an increase in the average value of 1.2 m4/kg s, which means that it has sound quality improvement. Through this research, the Nakdong technique results are expected to be used as basic-data for further research and give a practical idea for using the traditional treatment method on the wood surface.