• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.988-991
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• 1996

The purpose of this thesis is to develop methods of designing robust LQR/LQG controllers for time-varying systems with real parametric uncertainties. Controller design that meet desired performance and robust specifications is one of the most important unsolved problems in control engineering. We propose a new framework to solve these problems using Linear Matrix Inequalities (LMls) which have gained much attention in recent years, for their computational tractability and usefulness in control engineering. In Robust LQR case, the formulation of LMI based problem is straightforward and we can say that the obtained solution is the global optimum because the transformed problem is convex. In Robust LQG case, the formulation is difficult because the objective function and constraint are all nonlinear, therefore these are not treatable directly by LMI. We propose a sequential solving method which consist of a block-diagonal approach and a full-block approach. Block-diagonal approach gives a conservative solution and it is used as a initial guess for a full-block approach. In full-block approach two LMIs are solved sequentially in iterative manner. Because this algorithm must be solved iteratively, the obtained solution may not be globally optimal.

• The Korean Journal of Pain
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• v.25 no.1
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• pp.38-42
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• 2012

Chronic pelvic pain is a common problem with variable etiology. The sympathetic nervous system plays an important role in the transmission of visceral pain regardless of its etiology. Sympathetic nerve block is effective and safe for treatment of pelvic visceral pain. One of them, the inferior hypogastric plexus, is not easily assessable to blockade by local anesthetics and neurolytic agents. Inferior hypogastric plexus block is not commonly used in chronic pelvic pain patients due to pre-sacral location. Therefore, inferior hypogastric plexus is not readily blocked using paravertebral or transdiscal approaches. There is only one report of inferior hypogastric plexus block via transsacral approach. This approach has several disadvantages. In this case a favorable outcome was obtained by using coccygeal transverse approach of inferior hypogastric plexus. Thus, we report a patient who was successfully given inferior hypogastric plexus block via coccygeal transverse approach to treat chronic pelvic pain conditions involving the lower pelvic viscera.

• The Korean Journal of Pain
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• v.33 no.2
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• pp.144-152
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• 2020

Background: Hemidiaphragmatic paralysis, a frequent complication of the brachial plexus block performed above the clavicle, is rarely associated with an infraclavicular approach. The costoclavicular brachial plexus block is emerging as a promising infraclavicular approach. However, it may increase the risk of hemidiaphragmatic paralysis because the proximity to the phrenic nerve is greater than in the classical infraclavicular approach. Methods: This retrospective analysis compared the incidence of hemidiaphragmatic paralysis in patients undergoing costoclavicular and supraclavicular brachial plexus blocks. Of 315 patients who underwent brachial plexus block performed by a single anesthesiologist, 118 underwent costoclavicular, and 197 underwent supraclavicular brachial plexus block. Propensity score matching selected 118 pairs of patients. The primary outcome was the incidence of hemidiaphragmatic paralysis, defined as a postoperative elevation of the hemidiaphragm > 20 mm. Factors affecting the incidence of hemidiaphragmatic paralysis were also evaluated. Results: Hemidiaphragmatic paralysis was observed in three patients (2.5%) who underwent costoclavicular and 47 (39.8%) who underwent supraclavicular brachial plexus blocks (P < 0.001; odds ratio, 0.04; 95% confidence interval, 0.01-0.13). Both the brachial plexus block approach and the injected volume of local anesthetic were significantly associated with hemidiaphragmatic paralysis. Conclusions: The incidence of hemidiaphragmatic paralysis is significantly lower with costoclavicular than with supraclavicular brachial plexus block.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.109-112
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• 1997

In this note, we investigate a noniterative design method of an observer-based robust H$\_$2/ controller in the presence of structured real parameter uncertainty by applying Riccati approach based on the guaranteed cost function. Motivated by the numerical difficulty of the problem, we try to develop a simple design method named as block-diagonal approach, which can be solved by the LMIs method. By assuming the block-diagonal structure of Riccati solution, the original problem can be derived into two sequentially decoupled optimization problems as LQG control problem. The proposed method seems to be numerically efficient in obtaining a feasible compensator.

• The Korean Journal of Pain
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• v.25 no.1
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• pp.43-46
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• 2012

The superior hypogastric plexus block (SHPB) is used for treating pelvic pain, especially in patients with gynecological malignancies. Various approaches to this procedure have been reported due to the anatomic obstacles of a high iliac crest or large transverse process of the $5^{th}$ lumbar vertebra. Here, we report a new technique of superior hypogastric plexus block using a unilateral single-needle approach to block the bilateral superior hypogastric plexus with a Tuohy needle and epidural catheter. We have confidence that this new technique can be another option in performing the SHPB when the conventional bilateral approach is difficult to perform.

• ETRI Journal
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• v.40 no.2
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• pp.266-274
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• 2018

In error-prone wireless environments, it is difficult to realize video coding systems that are robust to various types of data loss. In this paper, a novel motion-vector refinement approach is presented for video error concealment. A traditional boundary-matching approach is exploited to reduce blocky effects along the block boundary. More specifically, a downhill simplex approach is combined with a boundary-matching approach to fine-tune the motion vectors, reducing the blocky effects along the prediction unit block boundary, and minimizing the computational cost. Extensive simulations are performed, and the results obtained verify the robustness and effectiveness of the proposed approach.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.8
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• pp.317-323
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• 2017

This study was conducted to investigate the differences in magnetic resonance imaging (MRI) findings after lumbar epidural nerve block using the transforaminal approach and the interlaminar approach in patients with low back pain. This study was an observational analysis study of abnormal findings of MRI after epidural nerve block. This study included 78 patients who underwent MRI at approximately 24 h after lumbar epidural nerve block at a pain clinic of a university hospital between January 2007 and December 2016. Among patients who received epidural nerve block, 36 used the interlaminar approach and 42 used the transforaminal approach. The incidence of patients with abnormal changes in MRI findings was higher among patients using the interlaminar approach (53%) than those using the transforaminal approach (7%). Abnormal MRI findings included epidural air or fluid, needle tracks, and soft tissue changes, with epidural air being the most frequent abnormal finding (72%). We recommend use of the transforaminal approach to reduce the possibility of misreading or difficulty in interpretation of images of patients who underwent MRI at approximately 24 h after lumbar epidural nerve block. Practitioners should consider the possibility of abnormal findings such as epidural air on MRI in cases of epidural nerve block using the interlaminar approach.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.24 no.3
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• pp.243-291
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• 2020

In this paper, multi-block generalized backward differentiation methods for numerical solutions of ordinary differential and differential algebraic equations are introduced. This class of linear multi-block methods is implemented as multi-block boundary value methods (MB₂ VMs). The root distribution of the stability polynomial of the new class of methods are determined using the Wiener-Hopf factorization of a matrix polynomial for the purpose of their correct implementation. Numerical tests, showing the potential of such methods for output of multi-block of solutions of the ordinary differential equations in the new approach are also reported herein. The methods which output multi-block of solutions of the ordinary differential equations on application, are unlike the conventional linear multistep methods which output a solution at a point or the conventional boundary value methods and multi-block methods which output only a block of solutions per step. The MB₂ VMs introduced herein is a novel approach at developing very large scale integration methods (VLSIM) in the numerical solution of differential equations.

• Smart Media Journal
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• v.6 no.2
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• pp.9-14
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• 2017

A packet loss in wireless environments causes a severe degradation of video quality in video communications. In this paper, a novel video error concealment algorithm is presented by combining boundary errors and a block reliability measure. The block reliability measure decides the reliability of a block by checking residual errors of a block. In the proposed approach, a motion vector of a missing unreliable block in an inter coded frame is obtained initially based on the motion vector of the same block in the reference frame. Furthermore, if the block in the reference frame is unreliable according to the reliability measure, a new motion vector is decided based on block boundary errors around the initial motion vector. According to our simulations, the proposed approach shows promising results for error concealment in error-prone wireless environments.

• The Korean Journal of Pain
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• v.13 no.2
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• pp.202-207
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• 2000

Background: Superior hypogastric plexus block has been advocated as a useful technique for the treatment of cancer related pelvic pain. The aim of this study was to evaluate the effect of neurolytic trans-intervertebrodiscal superior hypogastric plexus block for pelvic cancer pain. Methods: Twenty-eight patients with gynecologic, colorectal or genitourinary cancer who suffered intractable pain were studied. We performed superior hypogastric plexus block by trans-intervertebrodiscal approach at L5/S1 level under the C-arm fluoroscopic guide unilaterally or bilaterally. Ten ml of 100% dehydrated alcohol was injected through each needle. We evaluated the change of visual analog pain score (VAS; 0~100 mm) and daily dose of oral morphine sulphate at the time of pre-block and 7 days after the block. Results: Fourteen patients (50%) had satisfactory pain relief (VAS<30) while five patients (18%) had moderate pain control (VAS 30~60). The remaining nine patients (32%) had mild or little pain relief (VAS>60) and their daily oral morphine doses were above 160 mg. Additional pain control method may be needed for those patients who received high dose of opioid before neurolytic block. Conclusions: We conclude trans-intervertebrodiscal neurolytic superior hypogastric plexus block was effective in relieving pelvic cancer pain. Neurolytic block, earlier stage, may provide better effects for more comfortable life at the end stage for cancer patients.