• Journal of Preventive Medicine and Public Health
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• 제31권4호
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• pp.644-665
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• 1998

This study was conducted to evaluate the health hazards and to develop early diagnostic methods of the manganism in experienced welders and to know the meaning of signal intensities on the brain Magnetic Resonance images. It was carried out from December 1996 to february 1997 with 277 male welders, the duration of welding was at least 5 years or more. The study was consisted of a questionnaire, physical examination and measurements of blood & urine manganese concentrations. Brain Magnetic Resonance imaging was done on 19 study subjects by random sampling. As the duration of welding increases, the positive rates of clinical symptoms, neurological examinations and blood manganese concentrations were also increased. However, physical examinations and urine manganese concentrations were not statistically significant with the duration of welding. Authors couldn't observe any Parkinsonism-like diseases. There were statistically significant correlations between duration of welding and blood manganese concentration(r=0.16, p<0.01). There were not statistically significant correlations between duration of welding and urine manganese concentrations (r=0.06). There were statistically significant correlations between blood & urine manganese concentration(r=0.34, p<0.01). By viewing brain Magnetic Resonance images, 13 welders(68.4 %) among 19 welders were found to have signal intensities. The positive rates of clinical symptoms, physical examinations, neurological examinations and blood & urine manganese concentrations were not statistically different between those with signal intensities and those without signal intensities. We would like to suggest that some non-specific clinical symptoms and neurological signs are correlated with the duration of welding but any Parkinsonism-like diseases had not been observed with these welders. Next we suggest that the high signal intensities on TlWI of brain Magnetic Resonance images are not the sign of manganese intoxication but the sign of manganese deposition.

• Journal of Korean Neurosurgical Society
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• 제38권2호
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• pp.102-106
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• 2005

Objective : The purposes of this study are to evaluate the efficacy of en bloc open-door laminoplasty and to investigate the validity of various factors as prognotic indicators in patients with multisegmental spondylotic myelopathy and ossification of posterior longitudinal ligament[OPLL]. Methods : The authors reviewed 43 cases in whom laminoplasty were performed for cervical myelopathy between January 2000 and December 2002. Clinical symptoms and results were evaluated using the Japanese Orthopaedic Association[JOA] scale. The recovery rate was calculated and then assessed for prognostic factors such as preoperative JOA scores, ages, history of previous trauma, duration of symptoms and signal change in cord on T2-weighted magnetic resonance Image. Results : In cervical stenosis, canal widening of antero-posterior diameter and dimension after laminoplasty is 4.16mm, $87.43mm^2$ and in OPLL is 6.20mm, $117.61mm^2$. In all cases there wasn't neurologic deterioration, mild postoperative complications developed in seven cases. Four patient had a limitation of range of neck motion and the other one showed kyphotic change and another two showed C5 radiculopathy. The recovery rate of JOA score in cervical stenosis and OPLL was 62% and 68% respectively. Duration of symptoms, the severity[preoperative JOA score], and signal change in cord on T2-weighted magnetic resonance image had close relationship to the clinical outcomes. Conclusion : Unilateral en bloc laminoplasty is simultaneous expansile and decompressive method. And preoperative JOA score, symptom duration and high signal intensity on T2-weighted magnetic resonance image can be used to predict prognosis.

• 한국자기공명학회논문지
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• 제10권1호
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• pp.46-58
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• 2006

With a simple pulse sequence ($\pi/2$-{gradient, duration T}-acquisition) in solution NMR, detected signal has slowly grown up to percents of the equilibrium magnetization. The source of this unusual resurrection of dephased magnetization after a crushed gradient is cross-correlated effects of radiation damping and the distant dipolar field, which has been demonstrated by a numerical simulation and theoretical analysis.

• 한국자기공명학회논문지
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• 제24권2호
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• pp.59-65
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• 2020

Nitrogen-Vacancy (NV) center in diamond has been an emerging versatile tool for quantum sensing applications. Amongst various applications, nano-scale nuclear magnetic resonance (NMR) using a single or ensemble NV centers has demonstrated promising results, opening possibility of a single molecule NMR for its chemical structural studies or multi-nuclear spin spectroscopy for quantum information science. However, there is a key challenge, which limited the spectral resolution of NMR detection using NV centers; the interrogation duration for NV-NMR detection technique has been limited by the NV sensor spin lifetime (T₁ ~ 3ms), which is orders of magnitude shorter than the coherence times of nuclear spins in bulk liquid samples (T₂ ~ 1s) or intrinsic ¹³C nuclear spins in diamond. Recent studies have shown that quantum memory technique or synchronized readout detection technique can further narrow down the spectral linewidth of NMR signal. In this short review paper, we overview basic concepts of nanoscale NMR using NV centers, and introduce further developments in high spectral resolution NV NMR studies.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.128.2-128
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• 2001

Since pulse energization can improve the performance of Electrostatic Precipitator(ESP) for high resistivity dusts, high voltage micro-pulse generators, 70kV 140usec duration pulses for instance, are commonly developed by LC resonance for most pulse powered ESPs. Consisting of discharge electrodes and collecting electrodes, ESP has its own capacitance like a capacitor. ESP's capacitance affects the LC resonance phenomenon with resonance inductor and capacitor of micro-pulse power supply, engineers should acquire the value of their ESP to design for proper power supply design. In this study, we describe the ESP's capacitance measuring device which has the same topology with our new developed micro-pulse power supply. In this microcontroller based capacitance measuring equipment, ESP's capacitance can be calculated easily through ...

• Journal of Korean Neurosurgical Society
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• 제40권3호
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• pp.169-174
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• 2006

Objective : This study was conducted to examine the correlation between clinical outcomes and the size of the syrinx in post-operative magnetic resonance imaging[MRI] and symptom duration. Methods : The authors investigated twelve patients who underwent various operations for syringomyelia from January 1995 to December 2003. The authors retrospectively analyzed medical records. pre- and post-operative MRI findings, features and durations of symptoms, and the method of surgical treatments. The clinical outcomes were assessed on Prolo scale at 6 months of post-operative period. Results : Neurologic symptoms did not promptly disappear after the shrinkage of syrinx, but post-operative MRI demonstrated most patients showed reductions in the size of the syrinx. There is no statistical relationship between clinical improvements and decrements of the syrinx size. However, patients who underwent surgical treatment within 2 years from the symptom onset had more favorable outcome than those who had operations after 2 years from the onset of symptoms. Conclusion : Change in the size of the syrinx in post-operative MRI is not directly proportional to favorable clinical outcomes. However, symptom duration before surgical treatment has considerable impact on the clinical outcomes.

• 한국지반공학회논문집
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• 제32권8호
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• pp.5-14
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• 2016

싱크홀 발생의 주요 원인인 하수관거 배면의 공동 탐지를 위해 비파괴검사 방법 중 하나인 충격반향법을 적용한 실내 모형 실험을 수행하였다. 콘크리트 하수관의 모의를 위해 얇은 두께의 콘크리트 평판 시험체를 제작하였고 주변지반은 모래로 조성하였으며 공동의 모사를 위해 스티로폼 박스를 모래에 매립하였다. 콘크리트 판 배면이 공동인 경우와 완전히 모래에 밀착된 경우로 나누어 실험이 진행되었으며 일정한 타격 강도의 유지를 위해 새롭게 제작된 타격 장치를 사용하여 획득 자료의 신뢰성을 높였다. 측정된 반사파는 고속 푸리에 변환과 국소 푸리에 변환을 사용하여 주파수 특성 및 시간 특성을 분석하였다. 그 결과, 푸리에 스펙트럼의 형상으로는 공동의 유무를 판별할 수 없는 것으로 나타났다. 본 연구에서는 공진 시간이라고 명한 새로운 지표를 제안하였다. 이는 공진 주파수가 일정 강도를 초과하는 지속 시간으로 정의하였다. 공진 시간은 공동의 유무를 효과적으로 예측하는 것으로 나타났다. 나아가 공동유무를 구분할 수 있는 공진 시간을 제시하였다. 실제 현장 조건에서의 검증과 보다 광범위한 적용성의 확보를 위해 다양한 지반 조건에 대한 추가 실험과 실제 하수관에 대한 현장 실험 등을 진행할 예정이다.

• Investigative Magnetic Resonance Imaging
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• 제19권2호
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• pp.99-106
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• 2015

Purpose: To investigate factors influencing the evaluation of background parenchymal enhancement (BPE) at follow-up breast magnetic resonance imaging (MRI) after adjuvant endocrine therapy. Materials and Methods: One hundred twelve women with breast cancer and MRI of the contralateral unaffected breast before and after endocrine therapy were identified. Two readers in consensus performed blinded side-by-side comparison of BPE (minimal, mild, moderate, and marked) before and after therapy with categorical scales. Age, body mass index, menopausal status, treatment regimen (selective estrogen receptor modulator or aromatase inhibitor), chemotherapy, follow-up duration, BPE at baseline MRI, MRI field strength before and after therapy, and recurrence were analyzed for their influences on decreased BPE. Results: Younger age, premenopausal status, treatment with selective estrogen receptor modulator, MRI field strength, and moderate or marked baseline BPE were significantly associated with decreased BPE. In multivariate analysis, MRI field strength and baseline BPE showed a significant association. Conclusion: MRI field strength and baseline BPE before and after therapy .were associated with decreased BPE at post-therapy, follow-up MRI.

• Investigative Magnetic Resonance Imaging
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• 제25권2호
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• pp.81-92
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• 2021

The role of neuroimaging in patients with acute ischemic stroke has been gradually increasing. The ultimate goal of stroke imaging is to make a streamlined imaging workflow for safe and efficient treatment based on optimized patient selection. In the era of multimodal comprehensive imaging in strokes, imaging based on computed tomography (CT) has been preferred for use in acute ischemic stroke, because, despite the unique strengths of magnetic resonance imaging (MRI), MRI has a longer scan duration than does CT-based imaging. However, recent improvements, such as multicoil technology and novel MRI acceleration techniques, including parallel imaging, simultaneous multi-section imaging, and compressed sensing, highlight the potential of comprehensive MR-based imaging for strokes. In this review, we discuss the role of stroke imaging in acute ischemic stroke management, as well as the strengths and limitations of MR-based imaging. Given these concepts, we review the current MR acceleration techniques that could be applied to stroke imaging and provide an overview of the previous research on each essential sequence: diffusion-weighted imaging, gradient-echo, fluid-attenuated inversion recovery, contrast-enhanced MR angiography, and MR perfusion imaging.

• 대한족부족관절학회지
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• 제23권4호
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• pp.183-188
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• 2019

Purpose: Bone contusion is usually treated with conservative therapy for 3 months. Bone contusion around knee and hip joints has been extensively reported on, but there are scant reports on this condition in foot and ankle joints. This study evaluated the nature, characteristics and location of bone contusion around foot and ankle joints to enlighten clinicians on how to better treat this disease entity. Materials and Methods: We classified bone contusion of the 76 patients into three types (102 sites; 47 ankle sprains, 18 traffic accidents, 11 falls) according to the Costa-Paz system with employing magnetic resonance imaging (MRI), and the study then analyzed the common sites and areas of occurrence according to the mechanism of injury and duration of pain after first conducting conservative therapy. Results: Of the 76 patients (102 sites) on the MRI, 43 case (42.2%) for talus, 19 cases for distal tibia, and 12 cases for calcaneus were involved. The classification, according to the Costa-Paz system, was Type I, 51 cases; Type II, 32 cases; and Type III, 19 cases. The duration of pain after conservative treatment was 12.15±2.17 weeks for Type I, 14.5±2.15 weeks for Type II, and 21.0±3.8 weeks for Type III. Conclusion: The most common location of post-traumatic bone contusion around both the foot and ankle is the talus, distal tibia, and calcaneus. The most common type of injury noted on MRI is a diffuse signal with change of the medullary component (Type I), In cases of bone contusion extending to a subjacent articular surface or disruption or depression of the normal contour of the cortical surface (Types II, III), the patients' pain appears to last longer. Thus, it is necessary to consider a longer period of conservative treatment in cases of Types II and III bone contusion because the patients' pain may last longer than 3 months.