• Nuclear Engineering and Technology
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• v.7 no.2
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• pp.95-106
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• 1975

A comparative study has been carried out on three silicon solar cell samples through their current-voltage (I-V) characteristics and their efficiencies. One sample is an ion-implanted cell made by our laboratory, and the other two samples are the dopant-diffused cells made by a foreign maker. The experiments have shown that both the properties of junction formation and the efficiency of each sample depend highly on the I-V characteristic of each p-n junction. The cause of incomplete properties in the ion-implanted sample has been clarified through this comparative study to be due to the various reasons such as slightly deficient surface impurity concentrations, defects induced by both the radiation and the foreign impurities, and insufficient ohmic contacts at the electrodes. The conversion efficiency of the ion-implanted sample can be figured out to be 4.2% whereas those of the other samples to be 14.3% and 8.3%, respectively.

• The Korean Journal of Pain
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• v.19 no.2
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• pp.146-151
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• 2006

Background: Spinal cord stimulation is a well-established method for the management of several types of chronic and intractable pain. This form of stimulation elicits a tingling sensation (paresthesia) in the corresponding dermatomes. The goal of this study was to establish a correlation between the spinal levels of the implanted epidural electrodes and the paresthesia elicited due to stimulation of the neural structures. Methods: Thirty five patients, who received trial spinal cord stimulation, were evaluated. After the insertion of the lead to the selected position, the areas of paresthesia evoked by stimulation were evaluated. Results: Seventy-one percent of cases showed paresthesia in the shoulder area when the tip of the electrode was located between the C2⁣-C4 levels. At the upper extremities, paresthesia was evoked in 86⁣-93% of cases, regardless of the location of the electrode tip within the cervical spinal segments. The most common tip placement of the leads eliciting hand stimulation was at the C5 level. The most common level of electrode tip placement eliciting paresthesia of the anterior and posterior thigh and the foot were at the T7-⁣T12, T10⁣-L1 and T11-⁣L1 vertebral segments, respectively. Conclusions: Detailed knowledge of the patterns of stimulation induced paresthesia in relation to the spine level of the implanted electrodes has allowed the more consistent and successful placement of epidural electrodes at the desired spine level.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.314-314
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• 2012

The dilute magnetic semiconductors (DMS) have been developed to multi-functional electro-magnetic devices. Specially, the Si based DMS formed by ion implantation have strong advantages to improve magnetic properties because of the controllable effects of carrier concentration on ferromagnetism. In this study, we investigated the deep level states of Fe- and Co-ions implanted Si wafer during rapid thermal annealing (RTA) process. The p-type Si (100) wafers with hole concentration of $1{\times}10^{16}cm^{-3}$ were uniformly implanted by Fe and Co ions at a dose of $1{\times}10^{16}cm^{-2}$ with an energy of 60 keV. After RTA process at temperature ranges of $500{\sim}900^{\circ}C$ for 5 min in nitrogen ambient, the Au electrodes with thickness of 100 nm were deposited to fabricate a Schottky contact by thermal evaporator. The surface morphology, the crystal structure, and the defect state for Fe- and Co- ion implanted p-type Si wafers were investigated by an atomic force microscopy, a x-ray diffraction, and a deep level transient spectroscopy, respectively. Finally, we will discuss the physical relationship between the electrical properties and the variation of defect states for Fe- and Co-ions implanted Si wafer after RTA.

• Journal of Chest Surgery
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• v.16 no.1
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• pp.115-120
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• 1983

We implanted pacemakers using screw-in sutureless myocardial electrode in 40 patients between February, 1980 and November, 1982 at Seoul Nation University Hospital. Mean age of total patient who received the pacemaker implantation was 39.9 years, but excluding the patient who received the open heart surgery, mean age was 49.3 years. Cause of pacemaker implantation was complete A-V block in 13 patients, symptomatic sick sinus syndrome in 12 patients, complete A-V block after open heart surgery in 12 patients, second degree A-V block with dizziness in one patient, and atrial fibrillation with slow ventricular response in two patients. In thirty nine cases, electrodes were implanted by subxiphoid approach, on the diaphragmatic surface of right ventricle. I n one case, electrode was implanted through the left anterior thoracotomy. Acute stimulation threshold, measured in 35 patients, varied from 0.1 to 2.5 mA [mean 0.85 mA.], and R-wave amplitude [sensitivity], measured in 19 patients, varied from 2.9 mV to 11.5 mV [mean 7.6 mV]. There was no hospital death. The postoperative complications included wound seroma in two patients [5%], wound hematoma in three patients [7.5%], and pacing failure in one patient [2.5%]. The subxiphoid implantation of the pacemaker using sutureless myocardial lead was valuable in obtaining safe, reliable and long-term impulse generation.

• The Korean Journal of Pain
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• v.19 no.1
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• pp.123-126
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• 2006

Spinal cord stimulation (SCS) has been used since 1967 for refractory chronic pain. SCS has recently undergone a variety of technical modifications and advances, and it has been applied in a variety of pain conditions. SCS has been most commonly applied for those patients with chronic back and leg pain and failed back surgery syndrome (FBSS). The clinical hallmark of FBSS is chronic postoperative pain. The pain pattern varies and the pain may show an axial or radicular distribution. Chronic intractable pain after FBSS is difficult to treat. This report describes our experience with treating chronic pain in two patients who suffered from FBSS with a spinal cord stimulator. A permanent spinal cord stimulator was implanted after a successful trial of stimulation with temporarily implanted electrodes. After 5 months of follow-up, the two patients had satisfactory improvement of their pain.

• Journal of Chest Surgery
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• v.14 no.2
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• pp.168-174
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• 1981

Since cardiac pacemaker was first totally implanted by Chardack, Gage and Greatbatch [1966], the electrical circuity of the cardiac pacemaker has been improved, modified, and refined. The problem of transvenous electrodes, however, is still remained; this may be due to electrode displacement, exit and/or entrance block, lead fracture and insulation defects. In permanent cardiac pacing, Irreversible loss of function of the transvenous electrode catheter eventually requires insertion of new lead. Authors now report one case that disclosed easy displacement of electrode tip in early phase of implantation and then two years and five months later, malfunctioning electrode could not be withdrawn from the cardiovascular system because it has become firmly enclosed by fibrous tissue along its course from the vein tract to the right ventricle. Under such circumstances, the electrode catheter tip was left in tricuspid annulus after being sutured at its entrance and burying the loop of lead in generator pocket. New other one electrode was then reimplantation through left external jugular vein.

• The Korean Journal of Physiology and Pharmacology
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• v.2 no.6
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• pp.687-693
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• 1998

This study was performed to examine the mean arterial pressure and nociceptive jaw opening reflex after microinjection of glutamate into the amygdala in freely moving rats, and to investigate the mechanisms of antinociceptive action of amygdala. Animals were anesthetized with pentobarbital sodium (40 mg/kg, ip). A stainless steel guide cannula (26 gauge) was implanted in the amygdala and lateral ventricle. Stimulating and recording electrodes were implanted into each of the incisor pulp and anterior digastric muscle. Electrodes were led subcutaneously to the miniature cranial connector sealed on the top of the skull with acrylic resin. After 48 hours of recovery from surgery, mean arterial pressure and digastric electromyogram (dEMG) were monitored in freely moving rats. Electrical shocks (200 ${\mu}sec$ duration, $0.5{\sim}2$ mA intensity) were delivered at 0.5 Hz to the dental pulp every 2 minutes. After injection of 0.35 M glutamate into the amygdala, mean arterial pressure was increased by $8{\pm}2$ mmHg and dEMG was suppressed to $71{\pm}5%$ of the control. Injection of 0.7 M glutamate elevated mean arterial pressure by $25{\pm}5$ mmHg and suppressed dEMG to $20{\pm}7%$ of the control. The suppression of dEMG were maintained for 30 minutes. Naloxone, an opioid receptor antagonist, inhibited the suppression of dEMG elicited by amygdaloid injection of glutamate from $28{\pm}4\;to\;68{\pm}5%$ of the control. Methysergide, a serotonin receptor antagonist, also inhibited the suppression of dEMG from $33{\pm}5\;to\;79{\pm}4%$ of the control. However, phentolamine, an ${\alpha}-adrenergic$ receptor antagonist, did not affect the suppression of dEMG. These results suggest that the amygdala can modulate both cardiovascular and nociceptive responses and that the antinociception of amygdala seems to be attributed to an augmentation of descending inhibitory influences on nociceptive pathways via serotonergic and opioid pathways.

• The Korean Journal of Physiology and Pharmacology
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• v.2 no.3
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• pp.307-312
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• 1998

This study was performed to investigate the mechanism of central analgesic effects of antidepressants. Thirty four male rats were anesthetized with pentobarbital sodium (40 mg/kg, ip). A stainless steel guide cannula and a PE tube (PE10) were implanted into the lateral ventricle and cisterna magna area. Stimulating and recording electrodes were implanted into the incisor pulp and anterior digastric muscle. Electrodes were led subcutaneously to the miniature cranial connector sealed on the top of the skull with acrylic resin. The jaw opening reflex was used in freely moving rats, and antidepressants were administered intracisternally in order to eliminate the effects of anesthetic agents on the pain assessment and evaluate the importance of the central action site of antidepressants. After 48 hours of recovery from surgery, digastric electromyogram (dEMG) of freely moving rats was recorded. Electrical shocks (200 ${\mu}sec$ duration, 0.5-2 mA intensity) were delivered at 0.5 Hz to the dental pulp every 2 minute. Intracisternal administration of $15\;{\mu}g$ imipramine suppressed dEMG elicited by noxious electrical stimulation in the tooth pulp to $76{\pm}6%$ control. Intracisternal administration of $30\;{\mu}g$ desipramine, nortriptyline, or imipramine suppressed dEMG remarkably to $48{\pm}2,\;27{\pm}8,\;or\;25{\pm}5%$ of the control, respectively. Naloxone, methysergide, and phentolamine blocked the suppression of dEMG produced by intracisternal antidepressants from $23{\pm}2\;to\;69{\pm}4%,\;from\;32{\pm}5\;to\;80{\pm}9%,\;and\;from\;24{\pm}6\;to\;77{\pm}5%$ of the control, respectively. These results indicate that antidepressants produce antinociception through central mechanisms in the orofacial area. Antinociception of intracisternal antidepressants seems to be mediated by an augmentation of descending pain inhibitory influences on nociceptive pathways.

• The Korean Journal of Pain
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• v.34 no.2
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• pp.156-164
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• 2021

Several types of pain occur following spinal cord injury (SCI); however, neuropathic pain (NP) is one of the most intractable. Invasive and non-invasive brain stimulation techniques have been studied in clinical trials to treat chronic NP following SCI. The evidence for invasive stimulation including motor cortex and deep brain stimulation via the use of implanted electrodes to reduce SCI-related NP remains limited, due to the small scale of existing studies. The lower risk of complications associated with non-invasive stimulation, including transcranial direct current stimulation (tDCS) and repetitive transcranial magnetic stimulation (rTMS), provide potentially attractive alternative central neuromodulation techniques. Compared to rTMS, tDCS is technically easier to apply, more affordable, available, and potentially feasible for home use. Accordingly, several new studies have investigated the efficacy of tDCS to treat NP after SCI. In this review, articles relating to the mechanisms, clinical efficacy and safety of tDCS on SCI-related NP were searched from inception to December 2019. Six clinical trials, including five randomized placebo-controlled trials and one prospective controlled trial, were included for evidence specific to the efficacy of tDCS for treating SCI-related NP. The mechanisms of action of tDCS are complex and not fully understood. Several factors including stimulation parameters and individual patient characteristics may affect the efficacy of tDCS intervention. Current evidence to support the efficacy of utilizing tDCS for relieving chronic NP after SCI remains limited. Further strong evidence is needed to confirm the efficacy of tDCS intervention for treating SCI-related NP.

• Proceedings of the KOSOMBE Conference
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• v.1991 no.05
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• pp.28-30
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• 1991

A visual prosthesis for the blind based upon electrical stimulation of the visual cortex requires the development of an array of electrodes. To establish design specifications for such an electrode array, we have conducted psychophysical experiments with normally sighted subjects wearing a portable 'phosphene' simulator. The simulator consists of a small video camera, a monitor masked by an opaque perforated film, and optical lenses. The visual angle subtended by the masked monitor is $1.7^{\circ}$ or less. We measured visual acuity and reading rate as a function of the number of pixels and their spacing. Our results indicate that a phosphene image produced by 600 electrodes implanted in a $1\;cm^2$, area near the foveal projection on the visual cortex should provide a limited but useful visual sense for the profoundly blind.