마이크로 컨트롤러를 이용한 지능구조물의 진동제어시스템 개발

황재혁,홍의표,이원석,최용훈 한국항공대학교 항공우주산업기술연구소 2003 航空宇宙産業技術硏究所 硏究誌 Vol.13 No.-

본 논문에서는 유연구조물의 진동을 제거하기 위하여 압전 세라믹(PZT)을 감지기와 작동키로 이용하였다. 진동을 제거하기 위한 제어 방법은 위치 되먹임 제어와 속도 되먹임 제어 두가지 방법을 사용하였다. 위치 되먹임 제어는 구조물의 각 지점의 위치를 감지해 내고 이를 역으로 걸어 주는 것이고 속도 되먹임 제어는 유연부착물의 각 지점에서의 속도에 대한 정보를 역으로 걸어 주는 것이다. 즉, 압전 감지기의 감지 전압을 이용해서 속도 되먹임 제어를 할 수 있다. 적용된 두 제어 방법 모두 개회로일 때 보다 좋은 성능을 나타내었다. 그러나 위치 되먹임 제어가 스필오버(spill-over)가 심했고 속도 되먹임 재어보다 정착시간(Settling Time)이 더 길었다. 본 실험에서는 속도 되먹임 제어가 적은 에너지로도 위치 되먹임 제어보다 좋은 성능을 보였다. 제어시스템을 구축하기 위해서 마이크로 컨트롤러를 사용한 제어보도를 설계하고 제작하였다. 제어 보드에 사용된 마이크로 컨트롤러는 Intel 80c196ke를 사용하였으며 마이크로 컨트롤러의 A/D, D/A 기능을 보완하기 위해서 A/D, D/A 보드를 제작하였으며, 사용자 편의와 원거리 제어를 위해서 사용자 보드를 제작하였다. 본 실험에서 제작한 제어 보드는 본 실험에 쓰인 외괄보 뿐만 아니라 압전 세라믹을 이용한 모든 구조물의 능동진동제어에 쓰인 수 있도록 제작되었다.

상악 유전치의 치근단 병소로 인한 만곡 영구전치

지혁준,최병재,이제호 대한소아치과학회 2001 大韓小兒齒科學會誌 Vol.28 No.1

치아만곡은 조직-형태분화기에 나타나는 치아형태의 이상으로 석회화된 부위와 미석회화된 부위간의 장애로 인해서 치관 및 치근 모두에서 발생하는 기형이며, 상악 절치에서 호발하며 매복 가능성이 높다고 보고되었다. 만곡의 원인으로는 유치의 외상, 치배의 이소성 발육, 낭종이 있으며 그외에 otodental syndrome, 쇄골두개이골증에서 보고되었다. 본 증례는 치아우식증으로 인해서 발생된 치근단병소가 치아만곡을 유발할 수 있는 원인이 될 수 있다고 생각하였기에 이에 보고하는 바이다. Dilaceration is a tooth abnormaly occuring in the histo-morphodifferention stage resulting from disturbance between the uncalcified and already calcified portion that affects both the crown and root. The involved tooth is usually the maxillary central incisor and it also shows high prevalence of impaction. The cause of dilaceration can be either from the trauma of the primary tooth, ectopic development of the tooth germ or from cysts. And it is also found in some cases of Otodental syndrome, Hurler syndrome, Cleidocranial dysostosis. The purpose of this study is to show that periapical lesions caused by dental caries can be another factor in causing dilacerations.

한약과 양약의 약물상호작용에 관한 연구(제1보) : Nicardipine과 청혈단의 상호작용 Effects of CHUNGHYULDAN on the Pharmacokinetics and Pharmacodydnamics of Nicardipine in Rats

김남재,진성민,최혁재,주수만,송보완,김종우 한국병원약사회 2002 병원약사회지 Vol.19 No.4

The influence of single and repeated oral pretreatment of CHUNG-HYUL-DAN(CHD). a widely used Korean traditional herbal medicines prescribed for hypertension and hyperlipidemia, on the pharmacokinetics and pharmacodynamics of a calcium channel blocker, nicardipine after oral administration of nicardipine was investigated in rats. The single pretreatment of CHD significantly increased area under the plasma concentration-time curve(AUC_(0-8h), but did not influence the time to reach the maximum peak plasma concentration(T_(max)), the maximum peak plasma concentration(C_(max)), terminal elimination half-life(t_(1/2) or the elimination rate constant(λ) for nicardipine. And, C_(max) and AUC_(0-8h) for nicardipine were significantly increased by with 1-week repeated pretreatment with CHD, but the other parameters were not significantly different from those of control. Also, the extent of the lowering effect of nicardipine on blood pressure in rats was significantly increased after oral administration of nicardipine with single and repeated oral pretreatment with CHD. These results indicated that single and 1-week repeated oral pretreatment with CHD should inhibit the metabolism of nicardipine in rats.

Pulsed Radiofrequency Neuromodulation Treatment on the Lateral Femoral Cutaneous Nerve for the Treatment of Meralgia Paresthetica

Choi, Hyuk-Jai,Choi, Seok-Keun,Kim, Tae-Sung,Lim, Young-Jin The Korean Neurosurgical Society 2011 Journal of Korean neurosurgical society Vol.50 No.2

We describe a rare case of pulsed radiofrequency treatment for pain relief associated with meralgia paresthetica. A 58-year-old female presented with pain in the left anterior lateral thigh. An imaging study revealed no acute lesions compared with a previous imaging study, and diagnosis of meralgia paresthetica was made. She received temporary pain relief with lateral femoral cutaneous nerve blocks twice. We performed pulsed radiofrequency treatment, and the pain declined to 25% of the maximal pain intensity. At 4 months after the procedure, the pain intensity did not aggravate without medication. Pulsed radiofrequency neuromodulation treatment on the lateral femoral cutaneous nerve may offer an effective, low risk treatment in patients with meralgia paresthetica who are refractory to conservative medical treatment.

New lesions detected within resection specimen by intraoperative ultrasound(IOUS) during hepatic resection for hepatocellular carcinoma(HCC) : IOUS findings and pathologic correlation

Hyuk Jai Jang,Jae Hong Ahn,Gun Moo Choi,Nam Kyu Choi,Jin Ho Kwak,Ji Hoon Kim,Chan Wook Kim,Myoung Sik Han 대한외과학회 2010 대한외과학회 학술대회 초록집 Vol.2010 No.11

Investigation of the transition between glow and streamer discharges in atmospheric air

Choi, Jai Hyuk,Lee, Tae Il,Han, Inho,Baik, Hong Koo,Song, Kie Moon,Lim, Yong Sik,Lee, Eung Suok IOP Pub ; American Institute of Physics 2006 Plasma sources science & technology Vol.15 No.3

<P>Generally, the parameter <I>p</I> · <I>d</I> (pressure × gap distance) in dielectric barrier discharge (DBD) controls the electrical breakdown and also the plasma characteristics. We investigated the optimum plasma transition <I>p</I> · <I>d</I> by controlling the pressure. To find the transition <I>p</I> · <I>d</I> (<I>p</I> · <I>d</I><SUB>tr</SUB>) condition, optical emission spectroscopy (OES) was used to measure emission spectra from the DBD. All <I>p</I> · <I>d</I> data were normalized by the second positive system of nitrogen molecules, the wavelength of which was 337.1 nm. Then we compared the relative intensities of species generated during the discharge by OES analysis. Species selected for comparison were the first negative system (FNS) of nitrogen molecules (391.4 nm) and atomic oxygen spectra (777.1 nm). Experimental results showed that relative intensities were almost constant as <I>p</I> · <I>d</I> decreased, but at specific <I>p</I> · <I>d</I> data, the intensity started to increase. The increase in FNS of nitrogen molecules means not only an increase in electron energy but also a change in the plasma mode, streamer to glow transition. In the case of DBD using alumina with 1 mm thickness applied ac power, the plasma transition occurred at the 1 Torr cm condition.</P>

Radiosurgical Techniques and Clinical Outcomes of Gamma Knife Radiosurgery for Brainstem Arteriovenous Malformations

Choi, Hyuk Jai,Choi, Seok Keun,Lim, Young Jin The Korean Neurosurgical Society 2012 Journal of Korean neurosurgical society Vol.52 No.6

Objective : Brainstem arteriovenous malformation (AVM) is rare and radiosurgical management is complicated by the sensitivity of the adjacent neurological structures. Complete obliteration of the nidus is not always possible. We describe over 20 years of radiosurgical procedures for brainstem AVMs, focusing on clinical outcomes and radiosurgical techniques. Methods : Between 1992 and 2011, the authors performed gamma knife radiosurgery (GKRS) in 464 cerebral AVMs. Twenty-nine of the 464 patients (6.3%) reviewed had brainstem AVMs. This series included sixteen males and thirteen females with a mean age of 30.7 years (range : 5-71 years). The symptoms that led to diagnoses were as follows : an altered mentality (5 patients, 17.3%), motor weakness (10 patients, 34.5%), cranial nerve symptoms (3 patients, 10.3%), headache (6 patients, 20.7%), dizziness (3 patients, 10.3%), and seizures (2 patients, 6.9%). Two patients had undergone a previous nidus resection, and three patients had undergone a previous embolization. Twenty-four patients underwent only GKRS. With respect to the nidus type and blood flow, the ratio of compact type to diffuse type and high flow to low flow were 17 : 12 and 16 : 13, respectively. In this series, 24 patients (82.8%) had a prior hemorrhage. The mean target volume was 1.7 $cm^3$ (range 0.1-11.3 $cm^3$). The mean maximal and marginal radiation doses were 38.5 Gy (range 28.6-43.6 Gy) and 23.4 Gy (range 18-27 Gy), and the mean isodose profile was 61.3% (range 50-70%). Results : Twenty-four patients had brainstem AVMs and were followed for more than 3 years. Obliteration of the AVMs was eventually documented in 17 patients (70.8%) over a mean follow-up period of 77.5 months (range 36-216 months). With respect to nidus type and blood flow, the obliteration rate of compact types (75%) was higher than that of diffuse types (66.7%), and the obliteration rate of low flow AVMs (76.9%) was higher than that of high flow AVMs (63.6%) (p<0.05). Two patients (6.9%) with three hemorrhagic events suffered a hemorrhage during the follow-up period. The annual bleeding rate of AVM after GKRS was 1.95% per year. No adverse radiation effects or delayed cystic formations were found. Conclusion : GKRS has an important clinical role in treatment of brainstem AVMs, which carry excessive surgical risks. Angiographic features and radiosurgical techniques using a lower maximal dose with higher isodose profiles are important for lesion obliteration and the avoidance of complications.

Clinical Outcomes of Pulsed Radiofrequency Neuromodulation for the Treatment of Occipital Neuralgia

Choi, Hyuk-Jai,Oh, In-Ho,Choi, Seok-Keun,Lim, Young-Jin The Korean Neurosurgical Society 2012 Journal of Korean neurosurgical society Vol.51 No.5

Objective : Occipital neuralgia is characterized by paroxysmal jabbing pain in the dermatomes of the greater or lesser occipital nerves caused by irritation of these nerves. Although several therapies have been reported, they have only temporary therapeutic effects. We report the results of pulsed radiofrequency treatment of the occipital nerve, which was used to treat occipital neuralgia. Methods : Patients were diagnosed with occipital neuralgia according to the International Classification of Headache Disorders classification criteria. We performed pulsed radiofrequency neuromodulation when patients presented with clinical findings suggestive occipital neuralgia with positive diagnostic block of the occipital nerves with local anesthetics. Patients were analyzed according to age, duration of symptoms, surgical results, complications and recurrence. Pain was measured every month after the procedure using the visual analog and total pain indexes. Results : From 2010, ten patients were included in the study. The mean age was 52 years (34-70 years). The mean follow-up period was 7.5 months (6-10 months). Mean Visual Analog Scale and mean total pain index scores declined by 6.1 units and 192.1 units, respectively, during the follow-up period. No complications were reported. Conclusion : Pulsed radiofrequency neuromodulation of the occipital nerve is an effective treatment for occipital neuralgia. Further controlled prospective studies are necessary to evaluate the exact effects and long-term outcomes of this treatment method.

Hemifacial Spasm Developed after Contralateral Vertebral Artery Ligation

Choi, Hyuk-Jai,Lee, Sung-Ho,Choi, Seok-Keun,Rhee, Bong-Arm The Korean Neurosurgical Society 2012 Journal of Korean neurosurgical society Vol.51 No.1

Although the mechanism of hemifacial spasm (HFS) is not yet well established, vascular compression of the facial nerve root exit zone and hyperexcitability of the facial nucleus have been suggested. We report a case of HFS in the setting of coinciding intracranial hemorrhage (ICH) of the pons and proximal ligation of the contralateral vertebral artery (VA) for the treatment of a fusiform aneurysm of the distal VA and discuss the possible etiologies of HFS in this patient. A 51-year-old male with an ICH of the pons was admitted to our hospital. Neuroimaging studies revealed an incidental fusiform aneurysm of the right VA distal to the origin of the posterior inferior cerebellar artery. Eight months after proximal ligation of the VA the patient presented with intermittent spasm of the left side of his face. Pre- and post-ligation magnetic resonance angiography revealed an enlarged diameter of the VA. The spasm completely disappeared after microvascular decompression.

latrogenic bile duct injury associated with anomalies of the right hepatic sectional ducts

Hyuk Jai Jang,Jin Ho Kwak,Gun Moo Choi,Nam Kyu Choi,Chan Wook Kim,Ji Hoon Kim,Myoung Sik Han 대한외과학회 2010 대한외과학회 학술대회 초록집 Vol.2010 No.11