Hyung-Man Cho

Semiempirical Analysis of Time-Dependent Elementary Polarizations in Electrochemical Cells

A systematic semiempirical way to analyze the variation in dc polarization with the operating time of electrochemical energy conversion devices is suggested. This includes the differentiation of the constituents of the total cell impedance, followed by the estimation of the time-dependent elementary contributions to the total polarization with the help of the theoretical analysis of an equivalent circuit. This unique method enables us to design high power energy conversion devices and, at the same time, effectively diagnose the power degradation of a cell. A comparative analysis of a fresh cell with an aged cell and the effect of temperature on polarization are exemplified. In particular, time-dependent contributions of elementary polarizations have been quantitatively suggested in each case with a strategy for the design of the materials. From this approach, power degradation after repeated battery cycling was ascribed to a rise in polarization due to the interfacial charge-transfer resistance of the cathode. Furthermore, the charge-transfer resistance of the cathode proved to be the most important factor in high rate battery discharging at ambient and low operating temperatures.

Bilateral optic neuritis associated with scrub typhus.

Scrub typhus is an acute febrile illness caused by Orientia tsutsugamushi and is transmitted to humans through the bite of the larval form of a mite [1]. This disease can cause not only dysfunction in multiple organs such as lung, heart, liver or spleen but also damage in the central or peripheral nervous system [1], either or both of which result in various neurological symptoms [2]. However, optic neuritis has not been previously reported as a clinical manifestation of scrub typhus. We describe a case of bilateral optic neuritis associated with scrub typhus. An 8-year-old boy presented to a local hospital with fever, chills, myalgia and diffuse rash for 1 week. He was noted to have an eschar on the right upper region of his body (Fig. 1a). Laboratory testing showed an antibody titer for O. tsutsugamushi of 1:5120, highly suggestive of scrub typhus. Fever, chills and myalgia rapidly resolved after doxycycline treatment. Two weeks later, he was transferred to our hospital because he developed loss of vision in the bilateral eyes. On examination, visual acuity was 20/200 in the right eye with sluggish pupillary reflex and no light perception in the left without reaction to light. Gadolinium enhanced T1-weighted MRI of the orbit showed enhancement of the bilateral optic nerves, indicative of bilateral optic neuritis (Fig. 1b). Ophthalmoscopy revealed marked edema of the bilateral optic discs (Fig. 1c and d). Routine complete blood count, serum biochemistry profiles, angiotensin-converting enzyme test, autoimmune antibody screening and chest radiography results were normal. Cerebrospinal fluid analysis was unremarkable. Cultures for bacteria, fungi and tuberculous bacillus and polymerase chain reaction for mycoplasma, mumps virus, varicella zoster virus, herpes simplex virus, cytomegalovirus, Epstein Barr virus, Hantaan virus, Leptospira and murine typhus in cerebrospinal fluid were negative. He was treated with intravenous methylprednisolone 800 mg for 5 days, followed by a tapering course of oral prednisolone. Visual acuity completely improved 3 months after receiving the steroid therapy. To our knowledge this is the first case of optic neuritis following infection with scrub typhus. Although the precise mechanism cannot be drawn from this case, the occurrence of bilateral optic neuritis at a convalescent period of scrub typhus suggests that the most probable mechanism is post-infectious inflammatory reaction as in acute disseminated encephalomyelitis [3,4]. Since infectious causes including viral, bacterial, protozoal, fungal and rickettsial disease may also lead to optic neuritis [5], extensive testing for infectious etiology should be performed to identify the relevant pathogen. In our case, the clinical course of delayed onset 3 weeks after the initial symptoms and favorable response to the steroid therapy without additional doxycycline administration may support a post-infectious etiology based on immune response, rather than optic nerve inflammation through direct infection. Scrub typhus can give rise to a wide spectrum of neurological manifestations such as meningoencephalitis, parkinsonism, transverse myelitis, demyelinating polyneuropathy, abducens or facial nerve palsy [2]. This case may allow us to add optic neuritis as a possible neurological complication of scrub typhus.

Design and Implementation of Sunlight-LED Dimming Control System for Sunlight Illuminating System

본 논문에서는 태양광 조명시스템에서 LED의 조도를 제어함으로써 실내로 출력되는 조명의 밝기를 일정하게 유지할 수 있는 태양광-LED 디밍 제어시스템을 개발한다. 광센서로 측정된 태양광의 세기에 따라 LED에 입력되는 전류의 크기를 조절하여 LED의 조도를 제어함으로써 태양광과 LED의 총 조도를 일정하게 유지한다. LED 디밍 제어 방식으로 일정한 출력 파장을 유지하는 장점이 있는 펄스 폭 변조(PWM) 방식을 채택한다. PWM 듀티비와 발생전류 사이의 비선형성을 보상하여 요구되는 LED 조도를 나타내는 지령 전압과 출력되는 LED 구동전류의 관계를 선형화함으로써 태양광 세기의 변화에도 실내의 밝기를 일정하게 제어한다. 태양광 직접 조명 장치를 이용한 실험을 통해 개발된 디밍 제어시스템의 성능을 검증한다.

Oculographic analysis of nystagmus in orthostatic vertigo

WCN 2013 No: 738 Topic: 36 Other Topic Viral meningitis triggers anti-NMDA receptor encephalitis C. Treepong, T. Termglinchan, M. Apiwattanakul. Department of Neurology, Prasat Neurological Institute, Bangkok, Thailand Background: Anti-NMDA receptor encephalitis is recognized increasingly in the past few years. Like other autoimmune diseases, environmental factors such as infection can precipitate autoimmune disease. Objective: To review clinical course of the patient who had viral meningitis with subsequently developed anti-NMDA receptor encephalitis. Patients and methods: A case report of twenty-seven year old priest who was admitted at Prasat Neurological Institute during 12th November to 14th December 2012. Results: A 27 year-old priest developed fever and nuchal rigidity for 2 weeks before arrival. Neurological examination showed neck stiffness, but fully consciousness. CSF analysis demonstrated pleocytosis 380 cells (lymphocytic predominate) with slightly elevated protein, but normal glucose. PCR for herpes was positive for Human herpesvirus type 7. During the course of intravenous acyclovir treatment, he was improved. But later on he developed acute psychosis, body stiffening with limb dystonia, dysautonomia and altered mental status respectively. MRI brain revealed abnormal signal at left posterior thalamus and left amygdala. EEG showed moderately severe diffuse encephalopathy. NMDA-receptor antibody was detected in CSF. The intravenous methylprednisolone and plasma exchange were started concurrently. Oral prednisolone and symptomatic treatment were continued. He was discharged after one month and his clinical full recovery after 1 month follow up. Conclusion: Human herpesvirus type 7 caused viral meningitis and trigger anti-NMDA receptor encephalitis. doi:10.1016/j.jns.2013.07.2110 Abstract WCN 2013 No: 747 Topic: 36 Other Topic Oculographic analysis of nystagmus in orthostatic vertigo WCN 2013 No: 747 Topic: 36 Other Topic Oculographic analysis of nystagmus in orthostatic vertigo J.-H. Choi, J.-D. Seo, H.-J. Cho, S.-H. Kim, J.-H. Bae, K.-D. Choi. Department of Neurology, Pusan National University Yangsan Hospital, Yangsan, Republic of Korea; Department of Neurology, Pusan National University Hospital, Republic of Korea; Department of Neurology, Dong-A University Hospital, Republic of Korea; Department of Neurology, Dae-Dong Hospital, Busan, Republic of Korea Background and objective: To elucidate objective vestibular dysfunction and the mechanisms of orthostatic vertigo. Materials and methods: Thirty-three consecutive patients with orthostatic dizziness/vertigo and profound orthostatic hypotension (OH) were recruited. Profound OH was defined that systolic BP falls of ≥30 mm Hg occurs within 3 min after standing and is sustained for at least 2 min during head-up tilt test. Eye movements were recorded during two orthostatic challenging test, the Schellong and Squatting–standing test. Results: All patients developed vertigo during orthostatic challenging test. Associated symptoms included blurred vision (45%), fainting (42%), and tinnitus (15%). Ten of 33 (30%) patients developed nystagmus during orthostatic challenging test with a latency of several seconds. Five of them showed mixed downbeat and horizontal nystagmus with or without torsional component, while the remaining four had pure downbeat nystagmus. In one patient, pure horizontal nystagmus and prominent downbeat nystagmus mixed with horizontal and torsional component appeared alternatively at a few second intervals. There were no significant differences in the mean drop of the BP between patients with or without nystagmus, but the patients with nystagmus had less longer duration of orthostatic vertigo than in patients without nystagmus (1.1 ± 1.6 vs 11.0 ± 9.7 mon, p b 0.001). Conclusions: The present study demonstrates that OH can give rise to true vestibular vertigo, which may be due to transient ischemia of the peripheral labyrinth or the central cerebellum based on the objective eye movement recording. The nystagmus in longstanding OH might have disappeared due to central adaptation by repetitive orthostatic vertigo. doi:10.1016/j.jns.2013.07.2111 Abstract WCN 2013 No: 741 Topic: 36 Other Topic A novel KRAS gene mutation of Noonan syndrome with severe peripheral nerve hypertrophy WCN 2013 No: 741 Topic: 36 Other Topic A novel KRAS gene mutation of Noonan syndrome with severe peripheral nerve hypertrophy Y. Ando, T. Kawakami, M. Morita, Y. Aoki, Y. Matsubara, I. Nakano. Department of Neurology, Jichi Medical University, Shimotsuke Tochigi, Japan; Department of Neurology, Oyama Municipal Hospital, Oyama Tochigi, Japan; Department of Medical Genetics, Tohoku University School of Medicine, Sendai Miyagi, Japan We reported a female case of Noonan syndrome (NS) with the significant peripheral nerve hypertrophy. Because her gait disturbance gradually deteriorated and the nerve conduction velocity was obviously reduced, we firstly thought she had Charcot–Marie–Tooth disease. But, she did not have the mutation of PMP22 gene. The NS with peripheral neuropathy was comparatively reported as the merger with neurofibromatosis (NF). Cafe au lait spots and skin tumors, which are characteristic in NF cases, were not seen in our case. The RAS/MAPK syndrome including NS, a Cardio-Facio-Cutaneous (CFC) syndrome, Costello syndrome and so on is proposed as a comprehensive concept of the congenital malformation diseases by the molecular abnormality of RAS/MAPK pathway in recent years. A novel KRAS gene mutation (c.211TNG, p.Y71D) was identified in our case. There was a previous report the KRAS gene mutation (c.211TNC, p.Y71H) in CFC syndrome case with peripheral nerve disorder. We think that the KRASmutation “p.Y71D”, “p.Y71H”may be related to peripheral nerve disorder closely. In addition, the peripheral nerve disorder is the phenotype of NS, CFC syndrome, and furthermore RAS/ MAPK syndrome. doi:10.1016/j.jns.2013.07.2112 Abstracts / Journal of the Neurological Sciences 333 (2013) e579–e628 e605