• Journal of Electrical Engineering and Technology
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• v.11 no.6
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• pp.1582-1589
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• 2016

In this paper the integration of Distributed Generation (DG) in radial distribution system is investigated by computing the optimal site and size of DG to be placed. An analytical expression based on equivalent current injection has been derived by utilizing topological structure of radial distribution system to find optimal size of DG to minimize losses. In the presented formulation, the optimal DG placement is obtained without repeatedly computing the load flow. The proposed formulation can be used to find the optimal size of all types of DGs namely Type-I, Type-II, Type-III and Type-IV DGs. The investigations are carried out on IEEE 33-bus and 69-bus radial distribution systems. The optimal DG placement results into reduction in active and reactive power losses and improvement in voltage profile of the buses.

• Clinical Endoscopy
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• v.56 no.1
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• pp.65-74
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• 2023

Background/Aims: Gastric varices (GV) are present in 25% of cirrhotic patients with high rates of rebleeding and mortality. Data on endoscopic ultrasound (EUS)-guided treatment in severe liver disease (model for end stage liver disease sodium [MELD-Na] >18 and Child-Turcotte-Pugh [CTP] C with GV) are scarce. Thus, we performed a retrospective comparison of endoscopic glue injection with EUS-guided therapy in cirrhotic patients with large GV. Methods: A retrospective study was performed in the tertiary hospitals of India. A total of 80 patients were recruited. The inclusion criteria were gastroesophageal varices type 2, isolated gastric varices type 1, bleeding within 6 weeks, size of GV >10 mm, and a MELD-Na >18. Treatment outcomes and complications of endoscopic glue injection and EUS-guided GV therapy were compared. Results: In this study, the patients' age, sex, liver disease severity (CTP, MELD-Na) and clinical parameters were comparable. The median number of procedures, injected glue volume, complications, and GV obturation were better in the EUS group, respectively. On subgroup analysis of the EUS method (e.g., direct gastric fundus vs. paragastric collateral [PGC] coil placement), PGC coil placement showed decreased coil requirement, less injected glue volume, decreased luminal coil extrusion, and increased successful GV obturation. Conclusions: EUS-guided treatment is more efficient and safer, and requires a smaller number of treatment sessions, as compared to endoscopic treatment in severe liver disease patients with large GV. Furthermore, PGC coil placement increases the complete obliteration of GV.

• The Korean Journal of Pain
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• v.19 no.1
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• pp.51-55
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• 2006

Background: A cervical transforaminal steroid injection is an effective therapeutic modality for radiculopathy of a herniated cervical disc or a cervical foraminal stenosis. However, there is some debate regarding the safety of the transforaminal approach under C-arm guidance compared with the posterior interlaminar approach. We report a new technique for cervical transforaminal steroid injection guided by MDCT. Methods: Patients presenting with radiating pain on their shoulder or arm were diagnosed using CT or MRI of a cervical herniated disc or a foraminal stenosis. Each patient whose symptoms were compatible with the image scan was enrolled in this study. They received a cervical transforaminal steroid injection under CT guidance, and the effectiveness and complications of this technique were evaluated over a 2-month period. Results: According to the CT scan, none of the participants had an internal jugular vein or a carotid artery invasion during the procedure. No vertebral artery injection was noted, and no patient developed a hematoma after the injection. The VAS score had improved significantly by 2, 4 and 8 weeks after the injection. Conclusions: While a conventional C-arm guided cervical transforaminal steroid injection does not appear to differentiate between the major vessels and structures in images, a CT guided approach is a more useful and safer technique for the precise placement of a needle.

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

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.50 no.1
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• pp.41-48
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• 2024

Objectives: Botulinum toxin type A (BTX), a powerful neurotoxin, can be an effective treatment choice for diverse muscular disorders and can reduce abnormal muscle activities. Abnormal movements of the mandible can be caused by involuntary and uncontrolled contractions of the lateral pterygoid muscle (LP) in various pathological situations. Previous reports have shown that BTX can reduce abnormal contractions of the LP. However, needle placement into the LP for BTX injection requires skill, experience, and sufficient anatomical knowledge. To place the needle precisely into the LP, ultrasonography (USG) can be used as an effective needle-guidance modality. USG is a non-invasive imaging modality able to create real-time images without any potential risks, including radiation exposure. Patients and Methods: The patients who had been performed USG-guided BTX injection into the LP using an intraoral approach were included in this study with a literature review and case presentations. Using the USG, four patients received BTX injections to treat recurrent temporomandibular dislocation and oromandibular dystonia resulting from involuntary LP activity. Result: Involuntary movements of the mandible were improved successfully in all patients, and showed satisfactory results without significant complication. Conclusion: The intraoral approach could prevent potential complications during needle placement. USG-guided BTX injection is an effective, convenient, and safe method that provides real-time imaging without unnecessary pain to the patient.

• Journal of the Korea Society for Simulation
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• v.9 no.2
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• pp.51-61
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• 2000

In recent years, significant advances in computers and communication technologies have made multimedia services feasible. As a result, various queueing models and cost models on architecture and data placement for multimedia server have been proposed. However, most of these models do not evaluate dependability of systems. In the design phase of a system, simulation is an important experimental means for performance and dependability analysis. Fault injection simulation has been used in evaluation of dependability metric. In this paper, we develop fault injection simulation model to analyze dependability of parallel video servers. In addition, we evaluate reliability and MTTF(Mean Time To Failure) of systems by using the simulator.

• The Korean Journal of Pain
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• v.28 no.2
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• pp.122-128
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• 2015

Background: Caudal epidural injections have been commonly performed in patients with low back pain and radiculopathy. Although caudal injection has generally been accepted as a safe procedure, serious complications such as inadvertent intravascular injection and dural puncture can occur. The present prospective study was designed to investigate the influence of the depth of the inserted needle on the success rate of caudal epidural blocks. Methods: A total of 49 adults scheduled to receive caudal epidural injections were randomly divided into 2 groups: Group 1 to receive the caudal injection through a conventional method, i.e., caudal injection after advancement of the needle 1 cm into the sacral canal (n = 25), and Group 2 to receive the injection through a new method, i.e., injection right after penetrating the sacrococcygeal ligament (n = 24). Ultrasound was used to identify the sacral hiatus and to achieve accurate needle placement according to the allocated groups. Contrast dyed fluoroscopy was obtained to evaluate the epidural spread of injected materials and to monitor the possible complications. Results: The success rates of the caudal injections were 68.0% in Group 1 and 95.8% in Group 2 (P = 0.023). The incidences of intravascular injections were 24.0% in Group 1 and 0% in Group 2 (P = 0.022). No intrathecal injection was found in either of the two groups. Conclusions: The new caudal epidural injection technique tested in this study is a reliable alternative, with a higher success rate and lower risk of accidental intravascular injection than the conventional technique.

• The Korean Journal of Pain
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• v.21 no.1
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• pp.57-61
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• 2008

Background: Shoulder joint injection is currently performed under fluoroscopic or computed tomography scan guidance. We performed this study to determine if an ultrasound guided shoulder joint injection through rotator cuff interval would have clinical usefulness. Methods: A total of 17 volunteers [12 women, 5 men; mean age 28 yr (23-32 yr)] received shoulder joint injection under multilinear ultrasound (5-10 MHz). Volunteers were positioned supinely on a table with their arm in a neutral position. The anterior shoulder region of the patient was sterilized using povidone iodine. A 24 gauge needle was introduced and directly visualized in real time as it passed obliquely from the skin surface to the inferior space of the biceps tendon. If there was little or no resistance to the injection, a contrast media (omnipaque) was injected and checked fluoroscopically. Results: Ultrasound guided shoulder joint injection through rotator cuff interval was successful in all cases. The average time taken for the procedure was $27.5{\pm}16.5sec$. The vertical distance from skin to the inferior space of the biceps tendon was $1.6{\pm}0.4cm$ and the distance of needle from the skin to the inferior space of biceps tendon was $2.8{\pm}0.6cm$. The procedure was well tolerated by all volunteers. Conclusions: Ultrasound guided shoulder joint injection through rotator cuff interval is an effective, rapid, and easy-to-perform injection technique. Ultrasound guided injection enables exact needle placement and avoids the use of both ionizing radiation and iodinated contrast material.

• The Korean Journal of Pain
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• v.20 no.1
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• pp.26-30
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• 2007

Background: Epidural steroid injections (ESI) are a common treatment for spinal disorders. Previous research has shown that aspiration of the syringe is not a sensitive test for placement of an intravascular needle. Serious complications have been reported from injection of steroids and local anesthetics into the vascular space. In addition to safety concerns, the efficacy may decline with partial injection outside the desired epidural location. We hypothesized that incidence of vascular problems is increased in patients who undergo spine surgery compared with the patients who don't undergo spine surgery. We investigated the incidence of vascular problems during lumbosacral transforaminal ESI and we compared the difference of vascular problems between the patients who undergo spinal surgery and those patients who don't undergo spinal surgery. Methods: Two hundreds and three patients were consecutively recruited and they received 299 fluoroscopically guided lumbosacral transforaminal ESIs. Injection of contrast was performed under live dynamic fluoroscopy with using digital substraction analysis. The observed uptake pattern was classified into one of three categories: flashback, aspirated, and positive contrast with negative flashback and aspiration. Results: The vascular incidence rate was 20.4%. Transforaminal ESIs performed at S1 had avascular incidence rate of 27.8% compared with 17.7% for all the other lumbar injection sites. The sensitivity of spontaneous observation of blood in the needle hub or blood aspirate for predicting an intravascular injection in lumbar transforaminal ESIs was 70.4%. Conclusions: There is a high incidence of intravascular problems when performing transforaminal ESIs, and this is significantly increased in patients with previous spine surgery. Using a flash or blood aspiration to predict an intravascular injection is not sensitive therefore; a negative flash or aspiration is not reliable. Fluoroscopically guided procedures without contrast confirmation are prone to instill medications intravascularly. This finding confirms the need for not only fluoroscopic guidance, but also for contrast injection instillation when performing lumbosacral transforaminal ESIs, and especially for patients with previous spine surgery.

• The Korean Journal of Pain
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• v.6 no.2
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• pp.265-269
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• 1993

Subdural block is a rare but well recognized complication of epidural anesthesia. The placement of local anesthetics into the subdural space can lead to potentially life-threatening conditions. A healthy 46-year-old women underwent total abdominal hysterectomy under continuous lumber epidural anesthesia. The technical procedure for continuous epidural catheterization went smoothly without a single problem. However, signs of high epidural block such as apnea, cranial nerve paralysis and pupil dilatation developed gradually, about 20 minutes after the epidural injection of 2% lidocaine 20 ml through the epidural catheter. Such extensive segmental block can only be explained as the result of injection into subdural space even if it was not confirmed radiologically.