• Journal of Power Electronics
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• v.14 no.6
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• pp.1208-1216
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• 2014

Mismatch between switching frequency and circuit parameters often occurs in industrial applications, which would lead to instability phenomena. The bifurcation behavior of $V^2$ controlled buck converter is investigated as the pulse width modulation period is varied. Nonlinear behavior is analyzed based on the monodromy matrix of the system. We observed that the stable period-1 orbit was first transformed to the period-2 bifurcation, which subsequently changed to chaos. The mechanism of the series of period-2 bifurcations shows that the characteristic eigenvalue of the monodromy matrix passes through the unit circle along the negative real axis. Resonant parametric perturbation technique has been applied to prevent the onset of instability. Meanwhile, the extended stability region of the converter is obtained. Simulation and experimental prototypes are built, and the corresponding results verify the theoretical analysis.

• Korean Journal of Veterinary Research
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• v.58 no.2
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• pp.111-114
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• 2018

A 6-year-old female domestic short hair cat presented with acute onset of vomiting, anorexia, lethargy, and tachypnea. The cat was apparently healthy prior to presentation without history of trauma. On diagnostic imagings, the entire stomach and spleen were detected in the thoracic cavity. An emergent celiotomy was performed, and a type-4 hiatal hernia was confirmed; the stomach, spleen, pancreas, and duodenum were herniated through the esophageal hiatus. It was corrected using phrenicoplasty, esophagopexy, and left-sided gastropexy and there was no recurrence 16 months after surgery. This is the first case report of an idiopathic type-4 hiatal hernia in a cat.

• Advanced Composite Materials
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• v.16 no.3
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• pp.223-244
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• 2007

This study experimentally and numerically investigated the tensile damage progress in stitched laminates. In particular, it focused on the effects of stitching on the damage progress. First, we experimentally confirmed that ply cracks and delamination appeared under load regardless of stitching. We then performed damage-extension simulation for stitched laminates using a layer-wise finite element model with stitch threads as beam elements, in which the damage (ply cracks and delamination) was represented by cohesive elements. A detailed comparison between observation and the simulated results confirmed that stitching had little effect on the onset and accumulation of ply cracks. Furthermore, we demonstrated that the stitch threads significantly suppressed the extension of the delamination.

• Journal of Korean Neurosurgical Society
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• v.47 no.3
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• pp.213-216
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• 2010

Spontaneous intracerebral hemorrhage (ICH) is a common condition that often leads to death or disability. Accurate prediction of the outcome and decisions regarding the treatment of ICH patients are important issues. We report a case of thalamic hemorrhage with an intraventricular hemorrhage that was suddenly migrated into the third and fourth ventricles in its entirety 8 hours after symptom onset. To our knowledge, this case is the first report of spontaneous migration of thalamic ICH into ventricles, and we suggest a possible mechanism for this case with a brief review of the literature.

• Archives of Craniofacial Surgery
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• v.17 no.4
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• pp.225-228
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• 2016

The entrapment of intracranial air from the check valve system results in a tension pneumocephalus. It should be distinguished from simple pneumocephalus because they are intracranial space-occupying masses that can threaten life. Communicating hydrocephalus is a serious and frequent complication of post-traumatic head injury. Head injury is one of the most common causes in etiopathogenesis of communicating hydrocephalus. Here, we describe a case of a 65-year-old man who developed communicating hydrocephalus after a post-traumatic tension pneumocephalus. To the best of our knowledge, this is the first reported case of communicating hydrocephalus developed after a post-traumatic tension pneumocephalus. Although the exact pathogenic mechanisms underlying the cascade following trauma remain unclear, communicating hydrocephalus after a tension pneumocephalus could be considered a possible complication.

• Journal of the Korean Home Economics Association
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• v.32 no.5
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• pp.97-108
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• 1994

This study attempted to explore the parents' parental satisfaction in Korea. Subjects who were selected nationwidely consisted of 1237 parents with children of the kindergarten and primary school. Parental Satisfaction Scale was used to examine the related variables pertaining to parental satisfaction. The results yielded the following conclusions; 1) The period of the transition to parenthood was too short. The mean interval between marriage and first child birth was 14.4 months. 2) Whereas fathers experienced greater parental role fulfillment than mother did mothers' employment status was not correlated with parental satisfaction. 3) Number and gender of the child and parent's educational attainment were related to parental satisfaction. However age at parental onset was not found as the related variable.

• Journal of the Korean Home Economics Association
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• v.49 no.9
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• pp.59-72
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• 2011

This study examined whether there are underlying latent classes of growth trajectories of maternal depression in the Korean population. Data from the first phase of the Panel Study of Korean Children (PSKC) of the Institute of Child Care and Education (KICCE) were used for this study. The final sample of participants included 1,471 mothers, who completed three interviews: at birth, at one month, and at four months. A two-class model consisting of depression (12.3%) and non-depression (87.7%) was considered the best-fitting solution using Mplus 3.13. The changes in postnatal depression in the Korean population within four weeks after childbirth, which is the period of "postpartum onset", seem to be important. Logistic regression analysis showed that duration of breast-feeding and planned pregnancy effects were significantly associated with trajectory class membership.

• The Journal of Korean Physical Therapy
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• v.21 no.1
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• pp.57-63
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• 2009

Purpose: We determined the recruitment pattern of lumbar elector spinalis, gluteus maxims, inner and outer hamstring muscle during trunk flexion and extension. Methods: Thirty healthy subjects(male; 15, female; 15) without low back pain and other problems in lower extremities participated in this study. To measure the recruitment pattern, the onset times of electromyographic activity of the muscles were recorded during trunk flexion and return(extension) to standing position. Results: The medial and lateral hamstring muscle was activated first, next elector spinalis, the last, gluteus maximus in trunk flexion. In trunk extension to standing position, the order of recruitment was similar to trunk flexion although the frequency is different. There were different between male and female in flexion and extension movement. Conclusion: The recruitment order of lumbar extensor and hip extensors in trunk flexion and extension will provide database in evaluation and intervention of lower back pain and lumbo.pelvic rhythm disorder.

• Annals of Clinical Neurophysiology
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• v.7 no.2
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• pp.138-140
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• 2005

Strumpell, in 1880, was the first to describe familial case of spastic paraplegia characterized by progressive weakness and spasticity of the lower limbs with little or no involvement of the upper extremities. This syndrome is heterogeneous in inheritance, age of onset, severity and associated signs. We present one family with autosomal dominant hereditary spastic paraplegia (HSP) due to SPG4 (spastin) gene mutation which is confirmed by genomic DNA isolated from peripheral blood.

• Annals of Clinical Neurophysiology
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• v.7 no.1
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• pp.31-33
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• 2005

Segmental zoster paresis (SZP) is a clinically rare complication of herpes zoster. But it has not been reported that acute cerebral motor cortical infarction coincidentally occurred in SZP. A 86-year-old woman was admitted due to pain, tingling sensation, and weakness of left arm. She had an acute onset of pain and tingling sensation in left arm at first day, shoulder weakness at second day, and multifocal vesicles at fourth day. Deep tendon reflexes of left arm were decreased than right. Electromyography showed an axonal polyneuropathy at superior trunk level of left brachial plexus. Median and ulnar sensory evoked potential tests were normal. Brain MRI showed a high signal in right primary motor cortex on diffusion weighted image. We report a case of acute cerebral motor cortical infarction coincidentally occurred in SZP.