• 한국산학기술학회논문지
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• 제22권1호
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• pp.37-44
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• 2021

수소연료전지차(FCEV)는 전기를 자체 생산하는 연료전지를 동력원으로 하고 있으며 기존 기계식 레귤레이터의 출구압은 시스템 사양에 의해 제작 시점에서 고정되며 순간적인 수소 공급량에 의한 출구압 강하가 발생하는 경우 수소의 공급유량이 부정확해지는 문제가 있다. 본 연구에서는 기존에 존재하는 1단 기계식 감압 레귤레이터를 보완하기 위한 2단 감압 레귤레이터의 형상 설계 및 재질 선정을 수행하였다. 2단계 감압을 통한 맥동과 느린 응답을 보상하고 고압 편차 문제를 해결하기 위해 감압 유닛의 접촉면 형상을 가공성을 고려하여 설계하였다. 기밀성 측면에서 TPU의 변형량은 최대 15.82% 작은 변위량을 보였으며, 재질 선정에서는 2단 감압에 보편성을 확보하고 다양한 수소 연료 공급시스템에 적용 가능한 전자식 솔레노이드를 고려하여 자성체를 선정하고 적절한 도금 종류를 검증하기 위한 수소 취성 및 내식성 평가를 실시하였다. 시편의 표면 부식은 Cr 도금의 경우에서만 발생되지 않았으며, 인장 시험을 통해 부식과정간 연신율을 비교하였을 때, 2% 이내의 차이를 확인하였다.

• 한국임상수의학회지
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• 제38권3호
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• pp.143-146
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• 2021

A 2-year-old intact female Maltese dog was presented with generalized involuntary tremors and nystagmus without regular direction. The dog was conscious the whole time while it was trembling. Its involuntary tremors were alleviated at rest or during sleep. Magnetic resonance imaging (MRI) revealed asymmetric hydrocephalus and caudal occipital malformation. In cerebrospinal fluid (CSF) analysis, a trace of protein was found and total nucleated cell count (TNCC) was slightly increased. However, infectious pathogens were not found. In complete blood count, there was a mild leukocytosis. After the patient received anticonvulsants (midazolam, phenobarbital, KBr), diuretics (furosemide) with an anti-inflammatory drug (prednisolone, 0.5 mg/kg PO bid), and a proton-pump inhibitor (omeprazole), it showed no improvement. The patient was tentatively diagnosed with corticosteroid responsive tremor syndrome. So the anticonvulsants and diuretics were discontinued and the dose of prednisolone was increased to an immunosuppressive dose (1 mg/kg PO bid). After administering the immunosuppressive dose of prednisolone, the patient did not show nystagmus. Its tremors were much alleviated. However, they did not disappear. Five weeks later, the patient showed gradual improvement but still was trembling when moving around. Nine weeks later, its tremors were similar to before. So diazepam (0.3 mg/kg PO sid) was added to the treatment. After that, its tremors were alleviated more. Prednisolone and diazepam were maintained for about five months, with tapering of the dose of prednisolone (until 0.5 mg/kg PO sid). About 7 months later after the treatment was started, the dog was trembling rarely except when it was excited. Therefore, diazepam was discontinued. This case describes a refractory white dog shaker syndrome successfully managed with long-term administration of a steroid and diazepam.

• 대한의용생체공학회:의공학회지
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• 제41권6호
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• pp.228-234
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• 2020

Superparamagnetic iron oxide nanoparticles (SPIONs) are approved by the Food and Drug Administration (FDA) in the United States. SPIONs are used in magnetic resonance imaging (MRI) as contrast agents and targeted delivery in nanomedicine using external magnet sources. SPIONs act as an artificial peroxidase (i.e., nanozyme), and these reactions were highly stable in various pH conditions and temperatures. In this study, we report a nanozyme ability of the clustered SPIONs (CSPIONs) synthesized by the oil-in-water (O/W) method and coated with biocompatible poly(lactic-co-glycolic acid) (PLGA). We hypothesize that the CSPIONs can have high sensitivity toward H2O2 derived from the reaction between a fixed amount of glucose and glucose oxidase (GOX). As a result, CSPIONs oxidized a 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) diammonium salt (ABTS) commonly used as a substrate for hydrogen peroxidase in the presence of H2O2, leading to a change in the color of the substrate. We also utilized a colorimetric assay at 417 nm using various glucose concentrations from 5 mM to 1.25 μM to validate β-D-glucose detection. This study demonstrated that the absorbance value increases along with increasing the glucose level. The results were highly repeated at concentrations below 5 mM (all standard deviations < 0.03). Moreover, the sensitivity and limit of detection were 1.50 and 5.44 μM, respectively, in which CSPIONs are more responsive to glucose than SPIONs. In conclusion, this study suggests that CSPIONs have the potential to be used for glucose detection in diabetic patients using a physiological fluid such as ocular, saliva, and urine.

• Pediatric Infection and Vaccine
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• 제29권1호
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• pp.54-60
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• 2022

살모넬라 수막염은 소아청소년에서 흔하지 않은 병이나 심각한 신경학적 합병증을 일으킬 수 있다. 영아, 특히 3개월 미만의 연령과 악성 종양, 말라리아 감염, 인체면역결핍바이러스 감염과 같은 면역 저하 상태는 살모넬라 수막염의 위험인자로 알려져 있다. 본 증례에서는 고열과 구토, 의식 변화를 주소로 내원한 이전 특이병력 없던 건강한 8세 여아의 살모넬라 수막염 증례를 소개한다. 환자의 뇌척수액에서 D군 살모넬라가 배양되었으며, 뇌 자기공명영상 소견은 정상이었다. 면역 글로불린 수치와 림프구 수는 정상 범위였고, 차세대 염기서열 분석에서 원발성 면역결핍 질환을 일으키는 유전자 변이는 검출되지 않았다. 3세대 세팔로스포린 투약으로 환자의 증상은 빠르게 호전되었으며 합병증이나 후유증은 발생하지 않았다. 비장티푸스 살모넬라균은 면역이 정상인 소아에서 수막염을 일으킬 수 있으며 조기에 항생제를 투여하면 성공적으로 치료할 수 있다.

• 대한의용생체공학회:의공학회지
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• 제44권1호
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• pp.53-63
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• 2023

There have been many studies from the genetic system to physical activity and emotional expression such that there are gender differences. The purpose of this study was to determine how the structural characteristics of cortical thickness differ between males and females. This study used data from the Human Connectome Project (HCP). To analyze age-specific sexual dimorphisms of cortical thickness, selected 8-80 year old subjects were divided into five detailed age range groups according to each criterion. A total of 1,700 individual brain MRI T1 data were registered in stereotaxic space for analysis and classified into white matter (WM), gray matter (GM), and cerebro-spinal fluid (CSF). For surface-based analysis, the WM/GM surface was reconstructed from a spherical polygon model with 40962 vertices per hemisphere, and each vertex was extended to the GM/CSF boundary. Cortical thickness was then measured between each vertex using the t-link method. In the statistical analysis, intracranial volume was used as a covariate to exclude the effect of the difference in brain size of each individual, and the result of using age as a covariate was added to confirm the age effect within each group. Gender differences in cortical thickness had significant results by group. This may be an index to explain diseases with sexual dimorphism in prevalence or become a basis for explaining the characteristics of each sex that appear in behavior, personality, and aging. Therefore, the results of our study could be a criterion for age classification in future studies and for understanding 'normal' sexual dimorphism.

• Pediatric Infection and Vaccine
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• 제29권3호
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• pp.173-178
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• 2022

Streptococcus intermedius는 입안, 상부 호흡기, 위장관 등에 정상 상재균 중 하나로 존재하는 그람 양성 산소내성 혐기성 알균이다. 면역저하나 심장질환자에서 외상 또는 침습적 치료 후에 발생하는 기회 감염의 원인이 될 수 있다. 저자들은 최근 침습적 치료나 외상 등 특이 과거력이 없이 건강했던 7세 소아에서 S. intermedius에 의해 발생한 엉덩관절 화농 관절염을 경험하였기에 보고하고자 한다. 환자는 내원 3주전부터 왼쪽 엉덩관절 통증이 있었으며, 본원 내원 당일부터 발열이 발생하였다. 엉덩관절 자기공명영상에서 왼쪽 엉덩관절의 급성 화농 관절염으로 진단한 후 수술적 배농을 시행하였고, 혈액과 흡인 관절액에서 S. intermedius가 배양되었다. 수술 후 2주간의 ceftriaxone 정맥주사 후 3주간의 amoxicillin 경구 항생제로 치료한 후 재발없이 안정된 상태를 보이고 있다.

• Tribology and Lubricants
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• 제39권4호
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• pp.133-138
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• 2023

This paper presents a discussion on lubricating oil filters. The maintenance of lubricating oil filters can improve the performance of mechanical systems and extend the service life of the lubricating oil. Therefore, the effective management of the lubricating oil can extend the service life of the machine and reduce maintenance costs. A representative method for managing lubricating oil is filtering the lubricating oil using a lubricant filter. However, effectively managing a lubricating oil using a lubricant filter requires an understanding of the related knowledge. In this paper, we present the definition, classification, characteristics, specifications, performance, and self-cleaning function of lubricating oil filters. The lubricant filters are classified based on the filter material, filtering method, filtering location, and amount of filtered fluid. Cellulose and glass fiber materials are conventionally used as materials for lubricant filters, and recently, metal materials, which show excellent durability, are being increasingly adopted. The filtering methods can be classified into physical, chemical, magnetic, and electric field methods, and the lubricant filters can be classified according to their location in the lubrication system. The beta ratio and efficiency of the lubricant filter can be determined based on the performance of the filter. Finally, there are many products or technologies that add a self-cleaning function to the filter to remove foreign substances or contaminants for efficient management.

• Journal of Korean Neurosurgical Society
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• 제66권1호
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• pp.82-89
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• 2023

Objective : Rathke's cleft cysts (RCCs) are nonneoplastic cysts. Most of them are asymptomatic and stable; when symptomatic, RCCs are surgically fenestrated and drained. However, the outcomes remain unclear. The authors evaluated the outcomes of RCC decompression. Methods : Between 2004 and 2019, 32 RCCs were decompressed in a single tertiary institution. The clinical characteristics, intraoperative findings, postoperative complications, and endocrinological and surgical outcomes were retrospectively reviewed. Patients who underwent sequential imaging at least twice and at least 12 months after surgery were included in the analysis. Results : Patients' mean age was 40.8±14.9 years, and 62.5% were women. The mean follow-up duration was 62.3±48.6 months. In 21 patients (65.6%), no residual cysts were identified on postoperative magnetic resonance imaging. Of the 18 patients with preoperative visual field defects, 17 (94.4%) experienced postoperative visual improvement. Postoperative complications included endocrinological deterioration in 11 patients (34.4%), permanent diabetes insipidus in 11 (34.4%), infection in four (12.5%), intrasellar hemorrhage in three (9.4%), and cerebrospinal fluid leak in two (6.3%). Follow-up images revealed cyst recurrence in nine patients (28.1%), an average of 20.4 months after surgery; in three patients, the cysts were symptomatic, and resection was repeated. Multivariable analysis revealed that postoperative endocrinological deterioration was the only independent factor associated with cyst recurrence (p=0.028; hazard ratio, 6.800). Conclusion : Our findings showed that although only cyst fenestration for decompression was performed to preserve pituitary function, more pituitary dysfunction occurred than expected. Besides, the postoperative hormonal deterioration itself acted as a risk factor for cyst recurrence. In conclusion, surgery for RCC should be more careful.

• 한국임상수의학회지
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• 제40권1호
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• pp.56-61
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• 2023

A 5-month-old female domestic short-haired cat presented with a history of seizure episodes for two months following an animal bite injury to the head. There were no remarkable findings on physical and neurological examination or blood analysis. Computed tomography revealed a fracture of the left parietal bone with an inward displacement of the bone fragment while magnetic resonance imaging revealed an enlarged temporal horn of the left lateral ventricle and a pseudomeningocele compressing the adjacent cerebral parenchyma. Subsequently, cerebrospinal fluid analysis results were normal. The patient was diagnosed with traumatic brain injury (TBI), with subsequent post-traumatic hydrocephalus (PTH) and pseudomeningocele. Despite treatment with phenobarbital and levetiracetam, seizures were not sufficiently controlled. Craniectomy for bone fragment removal and duraplasty were performed after a week. The patient then returned to normal condition with no further seizure activity. On repeated MRI two months after discharge, the hydrocephalus of the lateral ventricle and pseudomeningocele were enlarged; however, the patient maintained a good clinical status without any neurological signs. To the best of our knowledge, PTH and intracranial pseudomeningoceles have not yet been reported in cats. PTH and pseudomeningocele are among the complications of TBI and may not have any significant relevance with the clinical signs in this case. Thus, to broaden our knowledge about PTH and pseudomeningocele in cats, we describe serial changes in the clinical findings of this cat over the treatment period.

• Journal of Korean Neurosurgical Society
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• 제65권3호
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• pp.479-488
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• 2022

Objective : The surgical management of trigeminal neuralgia (TN) caused by petrous apex meningioma (PAM) is still a challenge because of the lesion's deep location and the surrounding complex structures. The authors describe the intradural anterior transpetrosal approach (ATPA) and its effect on the treatment of TN secondary to PAM. Methods : A retrospective analysis of 15 patients with TN secondary to PAM who underwent surgery via the intradural ATPA was conducted. The key techniques, which included drilling off the petrosal apex (PA) and opening the upper wall of Meckel's cave (MC), are described in detail. Results : Total removal of the tumor and complete pain relief (Barrow Neurological Institute I) were achieved in all 15 patients without significant morbidity. Five patients developed new facial numbness postoperatively, which disappeared within three months after surgery. The postoperative magnetic resonance imaging showed temporal lobe swelling in three patients, but no clinical symptoms. One patient had cerebrospinal fluid leakage and was managed with bed rest and temporary lumbar drainage. One patient had an intracranial infection and was treated with antibiotics. By the last follow up, no patients had pain relapse or/and tumor recurrence. It is worth noting that the vascular compression at the root of the trigeminal nerve was found in one patient during the operation. Conclusion : Our experience suggests that drilling off the PA and opening the upper wall of the MC are key elements for a good outcome of the treatment of TN secondary to PAM. The intradural ATPA has the advantages for both tumor resection and pain relief.