• Journal of Korean Neurosurgical Society
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• v.39 no.1
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• pp.20-25
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• 2006

Objective : The authors analyze prospectively the result of transcranial doppler[TCD] in normal pressure hydrocephalus and compared its cerebral blood flow parameters to radionuclide cerebrospinal fluid[CSF] flow study, postoperative brain computed tomography[CT] findings and clinical outcome, and studied the relationship between cerebral hemodynamics and clinical performance. Methods : Twenty five patients with hydrocephalus undertook pre- and post-operative TCD but only preoperative CSF flow study was performed. Mean flow velocity[Vm], pulsatility index[PI] and resistance index[RI] were assessed through TCD and changes in ventricle size and cortical gyral atrophy were checked through brain CT. Results : Postoperative hydrocephalus showed an increase in Vm[ACA P=0.037, MCA P=0.034], decrease in PI[ACA P=0.019, MCA P=0.017] and decrease in RI [ACA P=0.017, MCA P=0.021] compared to preoperative TCD parameters in the postoperative improvement group. In the postoperative improvement group, postoperative TCD parameters correlated with CSF flow study grade [Vm : $R^2=-0.75$, PI : $R^2=0.86$, RI : $R^2=0.78$] and ventriculocranial ratio change correlated with PI change [$R^2=0.73$]. The convexity gyral atrophy and initial TCD parameters showed close relationship to outcome. Conclusion : PI and RI can be used as an indicator of post operative prognosis, and with the addition of CSF flow study values, can also be used as a tool to predict pre-op and post-op patient status and successful shunt surgery.

• Transactions of Materials Processing
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• v.20 no.5
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• pp.369-376
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• 2011

A non-quadratic anisotropic strain rate potential was introduced as a conjugate potential of the yield stress potential Yld2000-2d to describe anisotropic behavior of sheet metals, in particular, aluminum alloy sheets under plane stress state. This strain-rate potential takes into account the anisotropic yield stresses and R-values measured along the directions measured at 0, 45 and 90 degrees from the rolling direction, as well as the balanced biaxial yield stress and strain-rate ratio. The convexity of the strain-rate potential was completely proven. The strain-rate potential was applied for two anisotropic aluminum alloy sheets, AA6022-T4 and AA2090-T3. The results verified that the strain rate potential properly described the anisotropic behavior of aluminum alloy sheets and was closely conjugate of Yld2000-2d under the plane stress state.

• Journal of Korean Neurosurgical Society
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• v.60 no.6
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• pp.723-729
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• 2017

Objective : Acute subdural hematoma (ASDH) is generally considered a condition that should be managed surgically. However, some patients initially receive conservative treatment, a subset of whom require surgical intervention later. This study aimed to evaluate the predictors of delayed surgical intervention in ASDH patients who are initially managed conservatively. Methods : From January 2007 to December 2015, 842 patients diagnosed with ASDH were treated at our institution. Among them, 158 patients with convexity ASDH were initially treated conservatively. Patients were divided into a delayed surgery group and a conservative group. Demographic characteristics, past medication and medical histories, and radiological and laboratory data were collected by retrospective chart review. Independent risk factors were identified with univariate and multivariate analyses. Results : Twenty-eight patients (17.7%) underwent delayed surgical intervention. Their mean age was 69.0 years, and 82.1% were male. Hypertension, diabetes mellitus, and heart disease prevalence and use of anti-platelet agents did not significantly differ from the conservative group. However, age (p=0.024), previous cerebral infarction history (p=0.026), increased maximal hematoma thickness (p<0.001), midline shifting (p=0.001) and accompanying subarachnoid hemorrhage (p=0.022) on initial brain computed tomography (CT) scan, low hemoglobin level (p<0.001), high leukocyte count (p=0.004), and low glucose level (p=0.002) were significantly associated with delayed surgical intervention. In multivariate analysis, increased maximal hematoma thickness (odds ratio [OR]=1.279, 95% confidence interval [CI] 1.075-1.521; p=0.006), low hemoglobin level (OR=0.673, 95% CI 0.467-0.970; p=0.034), and high leukocyte count (OR=1.142, 95% CI 1.024-1.272; p=0.017) were independent risk factors for delayed surgical intervention. Conclusion : Due to the high likelihood of delayed surgical intervention among minimal ASDH patients with a thicker hematoma on initial brain CT, lower hemoglobin level, and higher leukocyte count, these patients should receive more careful observation.

• The korean journal of orthodontics
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• v.31 no.3 s.86
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• pp.301-309
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• 2001

Because many of patients seeking orthodontic treatment worry about the facial appearance and their chief motivation for orthodontic treatment is facial esthetics, it is critical to understand the influence of gender or culture on the evaluation of profile esthetics. The purpose of this study was to find out any influence of gender or culture on judging good facial profile. 4 different groups were asked to evaluate 133 facial profiles to test the influence of gender or culture on judging good facial profiles. Those 4 groups consisted of 10 Korean males, 10 Korean females, 10 Korean American males, and 10 Korean American females. 2 evaluation systems were introduced, absolute and relative. Soft tissues of selected good profile group were analyzed and statistic analysis was performed. Conclusions were as follows 1. Inter-evaluator difference for judging good facial profile was statistically significant, even if there was general agreement for the best profile among 40 raters. 2. Gender difference under the same cultural environment was not significant statistically. 3. The same ethnic groups with different cultural background showed statistically different preference on judging good Profile. 4. Good facial profile group had their own characteristics compared to remaining group in several soft tissue measurements which were vertical facial ratio, soft tissue facial convexity, and antero-posterior relative lip position.

• The korean journal of orthodontics
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• v.23 no.4 s.43
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• pp.455-474
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• 1993

Degenerative joint disease(DJD) has hun known as one of the diseases which affect the middleor old-aged people. But as orthodontists are getting interested in the adult orthodontics, it is not rare for them to meet the open-bite patients with the TMJ DJD in their clinics. The purpose of this article is to investigate the cephalometric characteristics of the open-bite cases with TMJ DJD. Twelve TMJ DJD patients($15.1\~39.5$ years old) were selected from the patients who visited Department of Orthodontics, Seoul National University Hospital. Cephalograms were taken and means from 60 measurements were compared by t-test with those of the fifty four healthy adults($20.0\~26.7$ years old) who have normal occlusion and TMJ. In this study male and female are compared respectively, for in the normal samples 26 measurements showed significant differences between the male and the female. The results and conclusions axe as follows: 1 In DJD group, ANB and Angle of convexity decreased, which means the retruding of the mandible. The interincisal angle was smaller than that of the normal group. The means of the overbite were -2.1mm in male and -3.0mm in female, and the means of the overjet were 5.6mm in male and 6.7mm in female. The profile was similar to that of Angle's Class II div.1 open-bite. 2. SN-GoMe and FMA increased in DJD but SN-PP and FH-PP did not show any significant difference. In TMJ DJD open-bite cases, the bony structure lower than the palatal plane seemed to play an important role in developing open-bite. 3. In DJD group, PH-ArGo, SArGo and Y-sxis angle increased significantly, but genial angle showed no significant difference. The means of hか were 50.1mm in male and 40.2mm in female, which were significantly smaller than those of the normal(56.5mm in male, 50.9mm in female). These findings seemed to indicate the posterior rotation of mandible resulted from the shortening of the ramus height. 4. Anterior faical height(AFH), upper anterior facial height(UAFH) and lower anterior facial height (LAEH) of DJD showed no significant increase as compared with those of the noraml group. There was no significant difference in the ratio of upper anterior facial height to lower anterior facial height(UAFH/LAFH). But, lower posterior facial height(LPFH) was significantly smaller than that of the normal group. 5. It was thought that the peculiar profile of the TMJ DJD open-bite was resulted from the posterior rotation of mandible as the ramus became short following the degerative destruction of of the condylar head and neck.

• The korean journal of orthodontics
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• v.49 no.1
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• pp.3-11
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• 2019

Objective: The purpose of this study was to investigate the influence of heritability on the craniofacial soft tissue cephalometric characteristics of monozygotic (MZ) twins, dizygotic (DZ) twins, and their siblings (SIB). Methods: The samples comprised Korean adult twins and their siblings (mean age, 39.8 years; MZ group, n = 36 pairs; DZ group, n = 13 pairs of the same gender; and SIB group, n = 26 pairs of the same gender). Thirty cephalometric variables were measured to characterize facial profile, facial height, soft-tissue thickness, and projection of nose and lip. Falconer's method was used to calculate heritability (low heritability, $h^2$ < 0.2; high heritability, $h^2$ > 0.9). After principal components analysis (PCA) was performed to extract the models, we calculated the intraclass correlation coefficient (ICC) value and heritability of each component. Results: The MZ group exhibited higher ICC values for all cephalometric variables than DZ and SIB groups. Among cephalometric variables, the highest ${h^2}_{(MZ-DZ)}$ and ${h^2}_{(MZ-SIB)}$ values were observed for the nasolabial angle (NLA, 1.544 and 2.036), chin angle (1.342 and 1.112), soft tissue chin thickness (2.872 and 1.226), and upper lip thickness ratio (1.592 and 1.026). PCA derived eight components with 84.5% of a cumulative explanation. The components that exhibited higher values of ${h^2}_{(MZ-DZ)}$ and ${h^2}_{(MZ-SIB)}$ were PCA2, which includes facial convexity, NLA, and nose projection (1.026 and 0.972), and PCA7, which includes chin angle and soft tissue chin thickness (2.107 and 1.169). Conclusions: The nose and soft tissue chin were more influenced by genetic factors than other soft tissues.

• Investigative Magnetic Resonance Imaging
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• v.4 no.2
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• pp.100-106
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• 2000

Purpose : To evaluate the usefulness of cerebral blood flow measurement applied to perfusion weighted image with short-scan time single shot gradient echo-planar technique in measuring cerebral blood volume(rCBV) of normal rabbits. Materials and methods : With 2.1-3.6 kg weighted rabbits, image is acquired when they are in supine position in children positioner. Perfusion weighted image is acquired to 44 seconds per 1 second successively. After 4 seconds later, Gd-DTPA 2ml are injected into int. jugular vein with 2 ml per second and normal saline is also injected after that. Same technique is applied 2 times per 30 minites in same rabbit. After Image is obtained in two part of cerebral cortex at vertex, convexity, in one of basal ganglia with choosing about $3-5{\textrm{mm}^2}$ areas. Curve of signal intensity changes in time sequence is drawn. After this images are transmitted by PC and software IDL, regional cerebral blood volume is measured with imaging processing program made by us. Results : With 22 of 24 rabbits, satisfactory 1-2 signal intensity versus time curve is made. Cerebral blood capacity and contrast media stay time (ST) is measured in two cerebral cortex and basal ganglia refering in parietal cerebral cortex. Mean focal cerebral blood flow capacity ratio in cortex was $0.97{\pm}0.35$ and in basal ganglia, $0.99{\pm}0.37$, mean contrast media stay time in cortex was $9.83{\pm}1.63$ sec and in basal gaiglia, $9.42{\pm}1.14$ sec, but there was no statistically significant difference between two areas ($\rho$=0.05). Conclusion : In cerebral cortex and basal ganglia, there is no difference in mean focal blood volume and mean contrast stay time. Therefore, PWI is useful in cerebral blood flow and early diagnosis, prognosis of cerebral ischemic disease. Hereafter, it is helpful in analysing cerebral blood flow changes with comparison difference in rCBV between normal tissue and ischemic tissue, and that with DWI finding in infarcted patient.