• 대한기계학회논문집B
• /
• 제35권7호
• /
• pp.709-715
• /
• 2011

대칭익형 단면에 미세한 피치각의 차이를 가지는 두 개의 로터 블레이드의 끝에서 발생하는 와류들의 상호 간섭을 관측하기 위하여 2차원 LDV를 활용하여 끝와류의 회전속도 성분과 축방향속도 성분들을 후류시기에 따라서 측정하였다. 선행 블레이드는 끝와류 축방향 성분이 정규분포를 나타내는 상사성을 위배한 반면, 후행 블레이드는 회전속도 성분이 복합와류를 나타내는 Vatistas' n=2 모형의 상사성을 위배하는 것으로 관찰되었다. 또한, 후류시기 200~240도 근방에서 두 끝와류의 궤적이 근접되어 상호 간섭을 나타내는 것으로 밝혀졌으며 이 시기 동안 후행블레이드의 와류이완 현상이 발생하는 것으로 확인이 되었다. 이러한 후류 간섭은 관절형 허브를 가지는 로터에서도 발생될 것으로 예측된다.

• Imaging Science in Dentistry
• /
• 제47권4호
• /
• pp.261-267
• /
• 2017

Purpose: Analyzing different patterns of maxillary sinus septa in cone-beam computed tomography (CBCT) images and predicting maxillary sinus membrane perforations. Materials and Methods: In this cross-sectional study, CBCT images of 222 patients ranging from 20 to 81 years old were evaluated. One hundred fifty-two patients (93 females and 59 males) who had maxillary sinus septa in axial views were included in this study. Cross-sectional images were used to determine classifications of sinus septa and the risk of membrane perforation using a method modified from Al-Faraje et al. Variables of sex, age, and dental status were considered. Chi-squared and Kruskal-Wallis tests were used for data analysis(P<.05). Results: In this study, 265 maxillary sinus septal patterns were found. The mean age of the patients was $44.1{\pm}14.7$ years old. The Class I and VII-div II patterns had the greatest and least prevalence, respectively. Furthermore, there was a significant relationship between the location of septa and the frequency of membrane perforation risk (P<.05). In this study, the relationship of different patterns of septa with dental status did not differ significantly (P>0.05). Conclusion: A higher prevalence of moderate risk of membrane perforation in the molar region relative to the premolar region was observed. Furthermore, maxillary sinus septa occur most frequently in the molar region, demonstrating the importance of paying attention to this region during sinus lift surgery. This study did not show any relationship between tooth loss and the presence of septa.

• 전자공학회논문지S
• /
• 제35S권6호
• /
• pp.66-71
• /
• 1998

본 연구에서 피부계통의 진단에 이용될 수 있는 고해상도 영상진단기를 개발하였으며 개발된 영상진단기는 sector scanning 방식으로서 A-mode, B-mode, M-mode의 80${\mu}m$ 축방향, 250${\mu}m$ 축방향 해상도로 $5mm {\times} 5mm$의 인체 단면 영상을 초당 20frame으로 나타낸다. 이 영상장치는 대부분의 피부학(dermatology) 계통의 질환에 그 병리학적인 연구에 이용될 수 있을 뿐만 아니라 안과(ophthalmology)나 치과(odontology) 계통의 병리학적인 판단에도 도움을 줄 수 있다고 생각되며 또한 피부미용(dermato-cosmetology)을 위한 분야에도 응용 가능하다.

• 대한핵의학회지
• /
• 제30권1호
• /
• pp.47-55
• /
• 1996

Progressive supranuclear palsy (PSP) is a parkinson-plus syndrome characterized clinically by supranuclear ephthalmoplegia, pseudobulbar palsy, axial rigidity, bradykinesia, postural instability and dementia. Presence of dementia and lack of cortical histopathology suggest the derangement of cortical function by pathological changes in subcortical structures in PSP, which is supported by the pattern of behavioral changes and measurement of brain metabolism using positron emission tomography. This study was done to examine whether there are specific changes of regional cerebral perfusion in PSP and whether there is a correlation between severity of motor abnormality and degree of changes in cerebral perfusion. We measured regional cerebral perfusion indices in 5 cortical and 2 subcortical areas in 6 patients with a clinical diagnosis of PSP and 6 healthy age and sex matched controls using $^{99m}Tc$-HMPAO SPECT. Compared with age and sex matched controls, only superior frontal regional perfusion index was significantly decreased in PSP (p<0.05). There was no correlation between the severity of the motor abnormality and any of the regional cerebral perfusion indices (p>0.05). We affirm the previous reports that perfusion in superior frontal cortex is decreased in PSP. Based on our results that there was no correlation between severity of motor abnormality and cerebral perfusion in the superior frontal cortex, nonmotoric symptoms including dementia needs to be looked at whether there is a correlation with the perfusion abnormality in superior frontal cortex.

• Investigative Magnetic Resonance Imaging
• /
• 제25권2호
• /
• pp.109-117
• /
• 2021

Purpose: To investigate the reliability of CT and MRI for quantitative and qualitative analyses of lumbar paraspinal muscle fatty infiltration (PSFI) and correlation of PSFI with intervertebral disc pathology. Materials and Methods: Lumbar spine CT and MRI of 36 subjects were reviewed retrospectively. Two observers independently outlined lumbar paraspinal muscles at each mid-intervertebral disc level. Paraspinal muscles on CT and MRI were graded according to the Goutallier grading system (GGS). The area, mean value, and standard deviation (SD) of the Hounsfield unit (HU) were obtained. Intervertebral discs were assessed on axial image of T2WI at each level. Correlations between qualitative and quantitative data and intervertebral disc pathology, age, and sex were evaluated. Results: Inter- and intra-observer agreements for results of GGS on MRI were substantial (κ = 0.79) and moderate (κ = 0.59), respectively. Inter- and intra-observer agreements for results of GGS on CT were almost perfect (κ = 0.88) and substantial (κ = 0.66), respectively. Quantitative measurements of HU showed almost perfect inter- and intra-observer reliabilities (κ = 0.82 and κ = 0.99, respectively). There were statistically significant correlations between intervertebral disc pathology and PSFI at L1-2, L2-3, and L4-5 levels on MRI and at L1-2 and L3-4 levels on CT. Age showed significant correlation with results of GGS at all levels on CT and MRI. Conclusion: This study showed that GGS results and HU measurements could be useful for evaluating PSFI because they showed correlations with intervertebral disc pathology results at certain levels.

• Journal of Korean Biological Nursing Science
• /
• 제24권1호
• /
• pp.17-25
• /
• 2022

Purpose: To determine the prognostic role of muscle area and muscle radiation attenuation in the erector spinae (ES) and multifidus (MF) muscles in patients undergoing gastrectomy. Methods: Patients with stage I-III gastric cancer undergoing gastrectomy were retrospectively enrolled in this study. Clinicopathologic characteristics were collected and analyzed. Both paraspinal muscle index of ES/MF muscles (PMI_EM) and paraspinal muscle radiation attenuation in the same muscles (PMRA_EM) were analyzed at the 3rd lumbar level using axial computed tomographic images. Cox regression analysis was applied to estimate overall survival (OS) and disease-free survival (DFS). Results: There was only a weak correlation between PMI_EM and PMRA_EM (r= 0.28). Multivariate Cox regression revealed that PMRA_EM, but not PMI_EM, was an important determinant of survival. PMRA_EM along with age, tumor-node-metastasis (TNM) stage, perineural invasion, and serum albumin level were significant determinants of both OS and DFS that constituted Model 1. Harrell's concordance index and integrated area under receiver operating characteristic curve were greater for Model 1 than for Model 2 (consisting of the same covariates as Model 1 except PMRA_EM) or Model 3 (consisting of only TNM stage). Conclusion: PMRA_EM, but not PMIEM, was an important determinant of survival. Because there was only a weak correlation between PMI_EM and PMRA_EM in this study, it was presumed that they were mutually exclusive. Model 1 consisting of age, TNM stage, perineural invasion, serum albumin level, and PMRA_EM was greater than nested models (i.e., Model 2 or Model 3) in predicting survival outcomes.

• 대한골관절종양학회지
• /
• 제2권1호
• /
• pp.111-115
• /
• 1996

Benign osteoblastoma, a rare tumor which forms osteoid and woven bone, represents 3% of benign and 1% of all primary bone tumors. It can involve anywhere in the axial skeleton, which is most common in the spine (34%). But the lesion of the calcaneus is extremely rare. The ratio of males to females is 2:1, with 80 percent of the patients being under thirty years of age. Pain is the most common symptom and rarely pathologic fracture. Osteoblastoma is a benign tumor but has a high recurrence rate after intracapsular malignant change. Therefore, choice of surgical procedure is the 'enbloc' resection. Authors have experienced a case of osteoblastoma developed in calcaneus. The treatment was wide resection and triple arthrodesis. We have reported here the case in which osteoblastoma occured in calcaneus of the right foot.

• 대한기계학회논문집B
• /
• 제24권10호
• /
• pp.1343-1350
• /
• 2000

The evolutionary structure of tip vortices has been investigated with a two-dimensional LDV system for a plain and a slotted blade, respectively. To analyze the effect of slots which bypasses a part of main stream into the tip face, velocity profiles, vortex sizes, their displacements and turbulence intensities during one revolution of the rotor were measured by the phase averaging process. For the comparison of circumferential velocity components of the plain blade and the slotted blade, the peak values of the slotted blade were lower than those of the plain blade, and axial velocity components of the slotted blade were considerably larger than those of the plain blade. The slotted rotor blade enlarged the core size and made the vortex delayed compared with those of the plain blade at the same wake ages. Turbulence profiles had peaks inside the core radii and decayed gradually in the radial direction of vortex coordinate. Also, using a quasi 3-D LDV measurement technique the budget of turbulence kinetic energy was analyzed in radial direction of the vortex core.

• 대한인간공학회지
• /
• 제24권4호
• /
• pp.47-53
• /
• 2005

This study aim to investigate the effects of supply of oxygen enhances cerebral activation through increased activation in the brain and using a 3 Tesla fMRI system. Five volunteers (right handed, average age of 21.3) were selected as subjects for this study. Oxygen supply equipment that provides 30% oxygen at a constant rate of 15L/min was given using face mask. A 3 Tesla fMRI system using the EPI BOLD technique, and three-pulse sequence technique get of the true axial planes scanned brain images. The author can get the perfusion images of the brain by oxygen inhalation with susceptibility contrast EPI sequence at the volunteers. Complex movement consisted of a finger task in which subjects flexed and extended all fingers repeatedly in union, without the fingers touching each other. Both task consisted of 96 phases including 6 activations and rests contents. Post-processing was done on MRDx software program by using cross-correlation method. The result shows that there was an improvement in performance and also increased activation in several areas in the oxygen method. These finding demonstrates that while performing cognitive tasks, oxygen administration was due to increase of cerebral activation.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• 제39권1호
• /
• pp.35-40
• /
• 2013

Osteochondroma is a common benign tumor of the axial skeleton, especially in the distal metaphysis of the femur and the proximal metaphysis of the tibia, that can occur on the facial skeleton (albeit rarely). Osteochondroma is differentiated from chondroma, osteochondromatosis and osteoma. Osteochondroma shows an irregular radiopaque lesion and chondromatic area surrounded by the osteoma. When it develops in the long bone, it has a marked tendency to occur at 10 to 20 years of age and ceases with the end of pubertal growth. However, when it develops in the mandibular condyle, it is prevalent in the third decade and continuous to develop. Tumors that develop in the long bone have a predilection for men, but tumors in the mandible have a predilection for women. In osteochondroma of the mandibular condyle, clinical features presented include occlusal changes, facial asymmetry, headaches, pain and joint noise on the temporomandibular joint, mouth opening limitations, and jaw deviation at the involved site. The first choice of treatment for the massive osteochondroma is surgical removal. A 70-year-old female patient with an osteochondroma on her right mandibular condyle visited our clinic. We surgically removed the mass with favorable results. It is presented here along with a review of literature on osteochondroma.