• Korean Journal of Applied Biomechanics
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• v.27 no.2
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• pp.149-155
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• 2017

Objective: The purpose of this study was to investigate the effects of three visual conditions (eyes opened, eyes closed, and wearing of a head mounted display [HMD]) on single-leg standing through kinematics and kinetic analysis. Method: Twelve college students (age: $24.5{\pm}2.6years$, height: $175.0{\pm}6.4cm$, weight: $69.2{\pm}5.1kg$) participated in this study. The study method adopted three-dimensional analysis with six cameras and ground reaction force measurement with one force plate. The analysis variables were coefficient of variation (CV) of the center of body mass, head movement, ground reaction force, and center of pressure, which were analyzed using one-way analysis of variance with repeated measures according to visual conditions. Results: In most cases, the results of this study showed that the CV was significantly higher in the order of HMD wearing, eyes closed, and eyes opened conditions. Conclusion: Our results indicated that body sway was the largest in the HMD wearing condition, and the risk of falling was high owing to the low stability.

• Korean Journal of Head & Neck Oncology
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• v.34 no.1
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• pp.33-36
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• 2018

Hyalinizing trabecular tumor (HTT) of the thyroid gland is a rare neoplasm and only less than 100 cases have been reported so far. It is characterized by hyalinizing stroma with trabecular growth pattern and has an indolent clinical course. Because of its histologic features, it is frequently misdiagnosed as papillary or medullary carcinoma in fine needle aspiration cytologic findings. The tumor is benign or low malignant potential and thyroid lobectomy is recommended for adequate treatment. We recently experienced a case of thyroidal HTT in a 57-year-old man, who presented with a right thyroid nodule that was suspicious of papillary carcinoma in aspiration cytology. We report the unique and rare disease entity with brief literature review.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.2
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• pp.93-98
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• 2008

We investigated the effect of process temperature on removal rate and non-uniformity based on single head kinematics in oxide CMP. Generally, it has been known that the temperature profile directly transfers to the non~uniformity of removal rate on the wafer, which has similar tendency with the sliding distance of wafer. Experimental results show that platen velocity is a dominant factor in removal rate as well as average temperature. However, the non-uniformity does not coincide between process temperature and removal rate, due to slurry accumulation and low deviation of temperature. Resultantly, the removal rate is strongly dependent on the rotational speed of platen, and its non -uniformity is controlled by the rotational speed of polishing head. It means lower WIWNU (With-in-wafer-non-uniformity) can be achieved in the region of higher head speed.

• Journal of Clinical Otolaryngology Head and Neck Surgery
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• v.29 no.2
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• pp.321-326
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• 2018

Warthin's tumor is the second most common benign tumor of the parotid gland, which consists of epithelial and lymphoid components. Malignant change is known to be extremely rare. In Korean literature, only a case of low grade adenocarcinoma arising from Warthin's tumor was reported. For squamous cell carcinoma, there has never been reported in Korea. The authors report a case of squamous cell carcinoma arising from Warthin's tumor in a 77-year-old male, who was treated with primary resection. The patient is well without any recurrence or metastasis after 15 months of follow-up.

• Korean Journal of Head & Neck Oncology
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• v.38 no.2
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• pp.1-5
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• 2022

Due to the low incidence and histologic diversity of salivary gland cancer, analyzing the incidence of salivary gland cancer is necessary to understand the macroscopic aspects. We intend to investigate the international trend of the reported incidence rate of salivary gland cancer. Using the Korea Central Cancer Registry data, the domestic change in the incidence rate was examined. As a result, a significant increasing trend was confirmed, consistent with the United States and Japan trends. The etiology of the change is unclear, and various factors that may influence the direction are reported. Additional research is needed to understand the pathophysiology of salivary gland cancer, and further efforts are required to understand salivary gland cancer.

• Journal of Korean Neurosurgical Society
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• v.65 no.3
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• pp.385-396
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• 2022

Abusive head trauma (AHT) in infants, especially acute subdural hematoma, has an extremely poor outcome. The most decisive and important finding is the appearance of a widespread low-density area on head computed tomography. This phenomenon was traditionally thought to be caused by cerebral ischemia. However, many other pathophysiological abnormalities have been found to be intricately involved. Recent studies have found that status epilepticus and hyperperfusion injures are the major causes. Another serious problem associated with AHT is cardiopulmonary arrest (CPA). Many infants are reported to visit to the hospital with CPA, and its pathophysiology has not been fully elucidated. This paper examines the background of these pathological conditions and associated factors and elucidate the pathophysiological mechanisms resulting in poor outcomes in AHT. In addition to the intensity of assault on the head, the peculiar pathophysiological characteristics in infants, as well as the social background specific to child abuse, are found to be associated with poor outcome.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.7 s.238
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• pp.784-794
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• 2005

In the very low specific speed range ($n_s=0.24$ < 0.25, non-dimensional), the efficiency of centrifugal pump designed by a conventional method is very low in common. Therefore, positive-displacement pumps have long been used widely. Recently, since the centrifugal pumps are becoming higher in rotational speed and smaller in size, there expects to develop a new centrifugal pump with a high performance to replace the positive-displacement pumps. The purpose of this study is to investigate the internal flow characteristics of a very low specific speed centrifugal pump and to examine the effect of internal flow pattern on pump performance. The results show that the theoretical head definition of semi-open impeller should be revised by the consideration of high slip factor in the semi-open impeller, and the leakage flow through the tip clearance results in a large effect on the impeller internal flow. Strong reverse flow at the outlet of semi-open impeller reduces the absolute tangential velocity considerably, and the decreased absolute tangential velocity increasese the slip factor with the reduction of theoretical head.

• The Korean Journal of Pain
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• v.5 no.1
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• pp.117-120
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• 1992

Non traumatic aseptic necrosis of the head of the femur is well documented with respect to its clinical roentgenographic and pathological aspect, but not with respect to etiology. A number of reports have associated various diseases and conditions with necrosis of the femoral head. Prominent among these are alcoholism, steroid therapy and hemostatic disorder. The increased incidence of avascular necrosis of bone associated with long-term corticosteroid therapy has aroused much interest. The pathogenesis of cortisone-induced avascular necrosis is as yet unproved. But cortisone-induced fatty liver with hyperlipidemia, leading to systemic embolization of fat and avascular necrosis of bone has much experimental support. We present a case of bilateral avascular necrosis of the femur head following several epidural steroid injections in a 30 year old male patient who had low back pain with radiation to both legs for 1 year and who had Cushinoid appearance for several months. One week later, he had a total replacement of both hip operation.

• Journal of the Korean Society of Propulsion Engineers
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• v.14 no.5
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• pp.92-100
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• 2010

Combustion stability rating tests of 75-tonf-class thrust chamber for technology demonstration were carried out at a low pressure. Two kinds of mixing heads were used in this study. One of them has injectors of 631 and the other has injectors of 721. Mixing head with injectors of 631 showed a self-oscillation instability at the chamber pressure of 30 bar. Mixing head with injectors of 721 showed that a high frequency combustion stability was maintained under the same pressure and the same mass flow rate. But mixing head with injectors of 721 generated a self-oscillation instability at the chamber pressure of 20 bar and it was found that stability boundary region was changed due to the configuration of a mixing head from these results.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.19 no.2
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• pp.133-135
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• 2008

Background and Objectives: The voice changes can occur in peritonsillar abscess and the labeling of this changes as a "muffled voice". The aim of this study was to investigate the changes in acoustic feature of voice before and after treatment in patients with peritonsillar abscess. Materials and Method: 12 patients with peritonsillar abscess were enrolled in the study. Acoustic analysis on sustained Korean vowels /a/, /i/ and /u/ were performed before and after treatment. Results: In patients with peritonsillar abscess, the first formant frequency (F1) and second formant frequency (F2) of /a/ were decreased. There was tendency of articulation of back-low vowel /a/ as back-high vowel /u/. F1 of /i/ and /u/ were increased, while F2 were decreased. There was tendency of articulation of front-high vowel /i/ as back-low vowel /a/. The third, forth, fifth formant frequency (F3, F4, F5) of /a/, /i/ and /u/ were decreased although statistically not significant. Conclusion: The anatomical and functional changes of oropharynx by peritonsillar abscess can cause changes in resonance and speech quality. We suggest that these changes could be the cause of 'muffled voice' in patients of peritonsillar abscess.