• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 합동 추계학술대회 논문집 정보 및 제어부문
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• pp.399-402
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• 2002

In this study, we constructed a four-channel impedance measurement system including a two-channel goniometer to analyze human arm movement. Impedances and joint angles were simultaneously measured for wrist and elbow movements. As the impedance changes resulting from wrist and elbow movements depended heavily on electrode placement, we determined the optimal electrode configurations for those movements by searching for high correlation coefficients, large impedance changes, and minimum interferences in ten subjects (age: 29+6). Our optimal electrode configurations showed very strong relationships between the wrist joint angle and forearm impedance (correlation coefficient = 0.95+0.04), and between the elbow joint angle and upper arm impedance (correlation coefficient = -0.98+0.02). Although the measured impedances changes of the wrist (1.1+1.5 ohm) and elbow (-5.0+2.9 ohm) varied among individuals, the reproducibilities of wrist and elbow impedance changes of five subjects were 5.8+1.8 % and 4.6+1.4 % for the optimal electrode pairs, respectively. We propose that this optimal electrode configuration would be useful for future studies involving the measurement of accurate arm movements by impedance method.

• Korean Journal of Radiology
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• 제24권8호
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• pp.761-771
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• 2023

Objective: To investigate the association among the electrode placement method, electrode type, and local tumor progression (LTP) following percutaneous radiofrequency ablation (RFA) for small hepatocellular carcinomas (HCCs) and to assess the risk factors for LTP. Materials and Methods: In this retrospective study, we enrolled 211 patients, including 150 males and 61 females, who had undergone ultrasound-guided RFA for a single HCC < 3 cm. Patients were divided into four combination groups of the electrode type and placement method: 1) tumor-puncturing with an internally cooled tip (ICT), 2) tumor-puncturing with an internally cooled wet tip (ICWT), 3) no-touch with ICT, and 4) no-touch with ICWT. Univariable and multivariable Cox proportional-hazards regression analyses were performed to evaluate the risk factors for LTP. The major RFA-related complications were assessed. Results: Overall, 83, 34, 80, and 14 patients were included in the ICT, ICWT, no-touch with ICT, and no-touch with ICWT groups, respectively. The cumulative LTP rates differed significantly among the four groups. Compared to tumor puncturing with ICT, tumor puncturing with ICWT was associated with a lower LTP risk (adjusted hazard ratio [aHR] = 0.11, 95% confidence interval [CI] = 0-0.88, P = 0.034). However, the cumulative LTP rate did not differ significantly between tumor-puncturing with ICT and no-touch RFA with ICT (aHR = 0.34, 95% CI = 0.03-1.62, P = 0.188) or ICWT (aHR = 0.28, 95% CI = 0-2.28, P = 0.294). An insufficient ablative margin was a risk factor for LTP (aHR = 6.13, 95% CI = 1.41-22.49, P = 0.019). The major complication rates were 1.2%, 0%, 2.5%, and 21.4% in the ICT, ICWT, no-touch with ICT, and no-touch with ICWT groups, respectively. Conclusion: ICWT was associated with a lower LTP rate compared to ICT when performing tumor-puncturing RFA. An insufficient ablation margin was a risk factor for LTP.

• 전기학회논문지
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• 제58권2호
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• pp.422-429
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• 2009

Meridian which used as the basic theory of acupuncture treatment, is an important functional connection system of acupuncture point in oriental medicine. Yangdorak and EAV have lack of precision because of using 2-electrode method, occurring high non-uniformed current density and electrode contact status on electrode placement spot. Therefore we implemented a meridian impedance measurement system for measuring meridian impedance using 4-electrode method. In order to confirm the precision of developed system, we made an constant current characteristic experiment using standard resistor. As a results of clinical study with 18 subjects, the meridian impedance showed that reproductivity and repeatability of HT7 acupuncture point are $0.515[k{\Omega}]{\pm}0.000$(mean${\pm}$standard deviation) and $0.515[k{\Omega}]{\pm}0.002$, respectively. And reproductivity and repeatability of PC7 are $0.521[k{\Omega}]{\pm}0.000$ and $0.521[{\Omega}]{\pm}0.001$ respectively. The proposed system was stable and reliable. Therefore this study proved AC impedance method to valid in measuring meridian impedance, and also verified precision and repeatability of the proposed meridian impedance measurement system. The proposed system will serve as more effective method of measuring meridian phenomena as a bioelectric signal in clinical practice.

• 대한의용생체공학회:의공학회지
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• 제9권1호
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• pp.31-36
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• 1988

A personal computer-based brain map is described which will display a gray scale maps showing the distribution of signals derived from the electrical activity of the brain such as EEG or EP This topographic brain mapping system has a flexibility which describe the electrode number and placement mapping onto any shaped space and generate a brain maps by incoorporated the data acquisition and processing software with conventional EEG machine.

• The Korean Journal of Pain
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• 제9권1호
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• pp.183-186
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• 1996

When medical therapy fail to relieve pain at tolerable level for patients confirmed with trigeminal neuralgia, presence of mass lesion excluded, surgery is indicated. Innumerable surgical strategies have been attempted for the treatment of trigeminal neuralgia but only four have proven appropriate: (1)stereotactic radiofrequency gasserian ganglionotomy, (2) percutaneous glycerol gangliolysis, (3) percutaneous microcompression, (4) microvascular decompression. Radiofrequency thermocoagulation of the gasserian ganglion stems from the efforts of Sweet. This technique is the surgical treatment of choice around the world for surgical treatment for trigeminal neuralgia. Since 1986, over 14,000 cases have been reported utilizing this technique. To improve the treatment method further, an electrode with a flexible curved tip has been developed for easier and more precise electrode placement and lesion production during the thermocoagulation of gasserian ganglion. This operation was performed recently on three patients at Hallym University Hospital. using a curved tip electrode. Complete relief of pain was achieved for all patient. However, some complications were noted.

• 생물정신의학
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• 제27권2호
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• pp.42-57
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• 2020

Electroconvulsive therapy (ECT) is indicated for various mental disorders (e.g., major depressive disorder, schizophrenia, and bipolar disorder) and the behavioral and psychological symptoms of dementia in elderly patients. Furthermore, ECT is a useful first-line treatment in emergency and crisis situations such as suicide risk, violent behavior, catatonia, and food refusal, which are more frequent in elderly patients. ECT is also effective in the treatment of the motor symptoms of neurological disorders, such as Parkinson's disease and Huntington's disease. Due to the high risk of various physical diseases, the comorbid physical conditions of elderly patients should be individually controlled to optimize ECT treatment. Compared to young adults, in elderly patients the seizure threshold is higher, the seizure duration is shorter, and the anesthetic dose is lower. On the contrary, the response rate in the elderly is both faster and higher. Considering potential cognitive decline and the prevention of further deterioration of cognitive function in elderly patients, in the absence of significant comorbidities, twice weekly sessions and right unilateral electrode placement with a lower seizure threshold and less cognitive effect are preferred to bilateral electrode placement, which has a high risk of adverse cognitive effects. After an acute course of ECT, continuation and maintenance of ECT, combined with prescription of therapeutic drugs, may prevent possible relapse or recurrence of mental disorders. In conclusion, ECT can be used to treat mental disorders in elderly adults, with safety and effectiveness comparable to that in young adults.

• 대한임상검사과학회지
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• 제45권4호
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• pp.170-179
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• 2013

There is a correct way to avoid any sequale in the central motor area during neurosurgery procedures. A clear way to find the circumference of the central sulcus, central motor, and sensory areas by giving cortical electrical stimulation to the central motor area immediate after surgery is proposed. Looking at patients who underwent brain surgery September 2009 to July 2013, the central sulcus and speech areas around the central area of the brain was investigated, using the practices of either a localized brain map check or a direct cortical electrical stimulation test. Brain maps localized around the surgical site through functional movement or speech areas were identified. Accurate tests done during surgery without damage to motor neurons or after surgery were conducted smoothly. Although successful brain map test localization can be accomplished, there are some factors that can interfere. The following phenomena can reverse the phase: (1) the first sensory / motor in the case of patients severe nerve damage; (2) placement of the electrode on top of the vessel; (3) presence of a brain tumor near the brain cortex; (4) use of anesthesia if patient cooperation is difficult; and (5) location of the electrode position and stimulus is inappropriate.

• The Korean Journal of Physiology
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• 제1권2호
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• pp.181-184
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• 1967

Hypothalamus is one of the most important center regulating voluntary and involuntary function of the body. We studied on the blood glucose and eosinophilic responses induced by electrical hypothalamic stimulation using stereotaxic apparatus. Blood glucose was measured according to Somogyi Nelson method and circulating eosinophil was counted with Hinkleman Stain. For the histological confirmation of electrode placement frozen sections were cut along electrode tract and stained with Hematoxylin-Eosin. The results obtained were as follows: 1. Anterior hypothalamic stimulation mostly leads to hypoglycemia but in some cases lead to hyperglycemia. 2. Hypothalamic stimulation leads to eosinopenia in majority cases. 3. There is no relationship between eosinopenia and hyperglycemia. 4. It appears that sympathetic and pararympathetic areas are not separate part but it coincides each other.

• The Korean Journal of Pain
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• 제19권2호
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• pp.244-248
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• 2006

Radiofrequency lesioning is a valuable tool for third occipital headache. Relative to most neural targets, a radiofrequency lesion is very small. Reliable pre-operative diagnosis of the nociceptive source is critical, as inappropriately placed lesions will not modulate pain. Knowledge of the anatomical courses of nerves and extremely precise electrode placement are required for accurate lesioning. This report describes our experience with RF lesioning in the treatment of chronic pain in two patients who suffered from third occipital headaches. In one patient, satisfactory improvement of the pain was observed after 10 months of follow up.

• Korean Journal of Radiology
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• 제20권4호
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• pp.580-588
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• 2019

Objective: To evaluate the impact of energy and access methods on extrahepatic tumor spreading and the ablation zone in an ex vivo subcapsular tumor mimic model with a risk of extrahepatic tumor spreading. Materials and Methods: Forty-two tumor-mimics were created in bovine liver blocks by injecting a mixture of iodine contrast material just below the liver capsule. Radiofrequency (RF) ablations were performed using an electrode placed parallel or perpendicular to hepatic surface through the tumor mimic with low- and high-power protocols (groups 1 and 2, respectively). Computed tomography (CT) scans were performed before and after ablation. The presence of contrast leak on the hepatic surface on CT, size of ablation zone, and timing of the first roll-off and popping sound were compared between the groups. Results: With parallel access, one contrast leak in group 1 (1/10, 10%) and nine in group 2 (9/10, 90%) (p < 0.001) were identified on post-ablation CT. With perpendicular access, six contrast leaks were identified in each group (6/11, 54.5%). The first roll-off and popping sound were significantly delayed in group 1 irrespective of the access method (p = 0.002). No statistical difference in the size of the ablation zone of the liver specimen was observed between the two groups (p = 0.247). Conclusion: Low-power RF ablation with parallel access is proposed to be effective and safe from extrahepatic tumor spreading in RF ablation of a solid hepatic tumor in the subcapsular location. Perpendicular placement of an electrode to the capsule is associated with a risk of extrahepatic tumor spreading regardless of the power applied.