• 제어로봇시스템학회:학술대회논문집
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• 1986.10a
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• pp.128-133
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• 1986

설비진단에 응용되는 신호처리의 기법으로는 파워스펙트럼, 바이스펙트럼, 켑스트럼 등이 사용되었다. 파워스펙트럼은 이론적인 면과 계산과정 그리고 신호처리에서의 적용방법등이 잘 알려져서 성공적으로 사용되어져 왔다. 특히 음향분야에서는 여러가지 응용기술이 개발되어 실제계에 적용되고 있으며 계측장비도 파워스펙트럼 해석법에 알맞게 개발되어져 왔다. 파워스펙트럼해석법을 사용하여 진동계를 구성하는 각 요소들의 고유진동수와 진동계 전체를 나타내는 진동파들의 주파수성분 간의 관계에 의하여 진동의 원인 및 소음원 등을 추정하는 것이 가능하다. 그러나 파워스펙트럼은 일반적으로 정상적인 신호를 갖는 진동계에 대한 해석 일 때는 그 이론과 실제가 잘 일치하지만, 진동계 자체가 항시 임의의 주파수를 갖고서 움직일 때 그 해석에는 다음과 같은 문제점이 생긴다. 첫째, 불규칙한 진동계에서는 규칙적인 진동계보다 잡음의 영향을 많이 받기 때문에 실제로 잡음이 진동계의 고유주파수 부근에 있을 경우에는 파워스펙트럼해석으로는 불가능한 경우가 있다. 둘째, 진동파 중에 포함되어 있는 위상이라는 중요한 정보가 없다. 셋째, 시간지연에 따른 진동계의 정확한 정보를 얻을 수 없다. 이상에서 볼 때 파워스펙트럼해석법은 한계가 있음을 알 수 있다. 따라서 본 논문은 바이스펙트럼이라는 해석법을 사용하여 정상과정에서 비정상과정으로 시간지연에따라 변하는 진동계 또는 정상적인 진동계의 저주파에서의 상호간섭 정도 및 위상관계를 관찰함으로써 파워스펙트럼과 비교하여 바이스펙트럼해석법의 타당성을 검토한다. 바이스펙트럼의 실제적인 계산방법은 P. J. Huber가 세가지 접근 방법을 제안했는데 시간영역에서의 평균화를 행하여 계산하는 법, 연속된 기록들을 평균화하는 것, 주파수 영역에서의 평균화를 행하는 것 등이 있다. 본 논문에서는 FFT를 먼저 행하고 파워스펙트럼과 바이스펙트럼 및 바이코히어런스를 구하였다. 그러나 바이스펙트럼해석법은 수치해석적인 면에서 볼 때 파워스펙트럼해석법에 비하여 미약한 점이 많고 통계학적인 그 의미가 확실하게 알려져 있지 않기 때문에 본 논문에서는 시뮬레이션을 통하여 그 물리적 의미를 규명하고져 한다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.1
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• pp.148-158
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• 2011

As critical infrastructure, bridges play an indispensable role in facilitating the distribution of goods. When bridges reach their end of useful life or get damaged by natural disasters such as earthquakes or storms, they have to be removed and reconstructed. When bridges in service need to be reconstructed, user costs occur from vehicle detours and traffic congestions, and social costs occur from noise and dust during construction periods. However, these user and social costs are not considered during reconstruction and the evaluation methods of those costs are vague. Thus, there is lack of appropriate bridge types that consider these costs. Therefore, this paper identifies the social overhead costs that occur during bridge reconstruction, which is also called, users' socioeconomic values. Next, it proposes a method to evaluate user costs during bridge reconstruction, and appraises the method. User costs are evaluated based on traffic information, social and material volumes including the bridge's daily traffic volume, peak hours, detour distance and time. In addition, time delay costs due to traffic operational costs and bridge reconstruction are also taken into consideration.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.6
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• pp.9-15
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• 2018

According to the development and use of self-consolidating concrete in field, interest in material properties of early-age concrete is rising. Setting time with hydration process of cement is one of significant indicator to evaluate the early-age material properties of concrete, various nondestructive methods including penetration resistance measurement have been proposed to estimate setting time. This study performed an experimental approach to evaluate setting time delay in mortar adding superplasticizer using electrical resistivity measurement. For this purpose, total nine types of mortar samples were prepared, and its electrical resistivity was monitoring during 24h after mixing. From the experimental result, rising time of electrical resistivity was used to evaluate setting delay of mortar, and penetration resistance was also measured for comparison. In addition, dynamic elastic modulus and compressive strength of 1day mortar were measured to investigate a possibility the use of electrical resistivity measurement for evaluation of early-age material properties.

• Journal of Korean Orthopaedic Sports Medicine
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• v.1 no.1
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• pp.75-78
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• 2002

Avulsion of the hamstring tendon from the ischial tuberosity is common in many sports, especially with younger athletes. The injury results from a sudden forceful flexion of the hip joint when the knee is extended and the hamstring muscles powerfully contracted. Early diagnosis and surgical repair with reattachment of avulsed muscles to the ischial tuberosity restore function and correct deformity. But, a delay in the diagnosis and treatment leads to a poor result functionally and clinically. Complication, such as heterotopic ossification and failure of the fixation, etc., were reported following a surgical procedure for this injury. However, sciatic nerve injury has not been reported in the literature. We report our experience of a sciatic nerve palsy after surgery that was performed three months after that the initial injury.

• Childhood Kidney Diseases
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• v.7 no.2
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• pp.239-244
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• 2003

$^{99m}Tc-MAG3$ Scintigraphic Scan is sensitive at depicting focal parenchymal abnormalities and can be used for the measurement of overall renal function. We experienced a 12-year-old girl presenting with fever and flank pain. On the ultrasonogram and post-voiding delayed image of $^{99m}Tc-MAG3$ scintigraphic scan, severe right cortical atrophy and hydronephrosis with vesicoureteral reflux were detected. We could demonstrate the reflux nephropathy by these two diagnostic work-up without conventional voiding cystourethrography.

• Clinical and Experimental Pediatrics
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• v.50 no.9
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• pp.868-874
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• 2007

Purpose : We performed this study to investigate the perinatal and developmental features of the patients with congenital myotonic dystrophy (CDM) confirmed by the molecular genetic method and the clinical characteristics of their mother, and to identify the relation between the number of CTG repeats and the clinical severity.Methods : A retrospective review of the medical records and the results of the dystrophia myotonica protein kinase (DMPK) gene test was done for the patients who were confirmed as CDM through gene analysis from January 2001 to September 2006. Results : All of the eight patients (male 2, female 6) showed moderate to severe degree of perinatal distress and feeding difficulty associated with profound hypotonia. Three patients had the history of polyhydramnios and two patients had equinovarus deformity. The developmental milestones were delayed in all patients, which improved gradually with age. All of their mothers demonstrated myotonic symptoms and typical myopathic face. The number of CTG repeats in DMPK gene analysis ranged 1,000-2,083, and there was no significant correlation between the number of CTG repeats and the time of walking alone. Conclusion : All patients with CDM presented with severe hypotonia in perinatal period, and developmental delay thereafter, which were improved with age. All of their mothers manifested myotonic symptoms with typical myopathic face, and the identification of such features greatly contributed to the diagnosis of the patients. The number of CTG repeats had no significant influence on the motor development.

• Clinical and Experimental Pediatrics
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• v.48 no.10
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• pp.1132-1138
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• 2005

Purpose : The mucopolysaccharidoses (MPSs) are a heterogeneous group of lysosomal storage disorders. They are caused by a deficiency of the enzymes involved in the degradation of glycosaminoglycans. Early recognition is important because recombinant enzyme replacement therapy is now available for MPS. We studied the clinical characteristics of 80 MPS children with the object of determining the epidemiological, clinical and radiological features in Korean MPS children. Methods : Diagnosis of MPS was confirmed by skin fibroblast enzyme analysis in 80 patients between February 1995 and December 2004. Charts were retrospectively reviewed for clinical and radiological findings, as well as for intelligence and speech evaluations. Results : Hunter syndrome (MPS type II) was the most prevalent type, appearing in 51/80 cases (64 %), followed by Sanfilippo syndrome (MPS III-18%), Hurler syndrome (MPS I-15%), and Morquio syndrome (MPS IV-4%). The average age at diagnosis was 5.5 years (range 1 to 20), and the male-to-female ratio was 4.7 : 1. Typical radiographic changes were observed in 45/54 cases (83%). Mitral regurgitation was the most common cardiac defect. Moderate to profound mental retardation and hearing loss were present in 14/35 cases (56%) and 33/38 cases (82%), respectively. Four MPS II patients had bone marrow transplantation, with mixed outcomes. Five MPS I patients are currently on enzyme replacement therapy. Conclusion : Our study showed a high proportion of MPS II cases (64%), which may represent population variability. By studying the clinical features of these patients, we hope to alert pediatricians of the warning signs of MPS.

• Clinical and Experimental Pediatrics
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• v.49 no.1
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• pp.76-81
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• 2006

Purpose : This study evaluated the clinical characteristics of brain tumors in children according to their location, the parental delay and the doctor's delay between the onset of symptoms and the diagnosis of a pediatric brain tumor. In addition, this study compared the relationship between the pre-diagnostic symptomatic interval and the tumor location. Methods : A retrospective study was undertaken of 45 children with primary brain tumors admitted to Inha Hospital from July, 1986 to June, 2004. A diagnosis of the tumor location was made using brain MRI. Results : The male to female ratio was 1 : 0.67. The median age at diagnosis was 6.0 years in supratentorial tumors, 7.0 years in infratentorial tumors. Twenty four cases(53.3 percent) were located in the supratentorial area, 21 cases(46.6 percent) were located in the infratentorial area. The distribution of supratentorial tumors were 14(58.3 percent) in the cerebral hemisphere and temporal lobe, seven (29.1 percent) in the suprasellar area, and three(12.5 percent) in the pineal gland and posterial lateral ventricle. The distributions of the infratentorial tumors were 12(57.1 percent) in the cerebellar vermis and fourth ventricle, four(19.1 percent) in the brain stem, and five(23.8 percent) in the cerebellar hemisphere. The most common initial symptom was seizure(37.5 percent) in the supratentorial tumor and headache(38.0 percent) in infratentorial tumors. The median pre-diagnostic symptomatic interval (PSI) was 21 days(range 0-240 days). The median PSI with a parental delay in supratentorial tumor was six days(range 1-240 days), and 30 days(range 1-40 days) in the infratentorial tumor. We immediately diagnosed most cases after visiting the hospital. There was no significant relationship between the tumor location and the pre-diagnostic symptomatic interval. Conclusion : The most common symptom of supratentorial tumors and infratentorial tumors was seizure and headache, respectively. Although, the median pre-diagnostic symptomatic interval was shorter than in previous studies, a detailed medical history and a correctly interpreted neurological examination should lead to an earlier diagnosis of pediatric brain tumors.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.6
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• pp.152-161
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• 2014

In this paper, a multi-node real-time diagnostic and management system based on zigbee sensor network is proposed, which is to monitor and diagnose multiple nodes as well as to control the data generated from the various multiple sensors collectively. The proposed system is designed to transmit the collected wireless and wired data to the server for monitoring and controling efficiently the condition for multi-nodes by taking the corresponding actions according to the analysis. The system is implemented to make it possible to manage the sensor data by classifying them, of which data are issued from the clustered sources with a number of the remote sensors. In order to evaluate the performance of the proposed system, we measure and analyze both the transmission delay time according to the distance and the data loss rate issued from multiple sensors. The results shows that the proposed system has a good performance.

• Journal of The Korean Society of Inherited Metabolic disease
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• v.14 no.2
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• pp.178-181
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• 2014

Hunter syndrome (mucopolysaccharidosis type II, MPS II) is a X-linked lysosomal storage disease caused by a deficiency in the lysosomal enzyme, iduronate-2-sulfatase (IDS), leading to accumulation of glycosaminoglycans within lysosomes of many organs and tissues. Since the enzyme replacement therapy was approved and available in the treatment of MPS I, II, VI, early diagnosis and early therapy can bring the better prognosis of disease and the better quality of life in patients. We described a 2.5 year old child presented with frequent otitis media and developmental delay including speech impairment, who was diagnosed as Hunter syndrome with IDS NM_000202.5:c. 263G>A(p.Arg88His) mutation.