• Journal of Korean Neurosurgical Society
• /
• v.62 no.6
• /
• pp.712-722
• /
• 2019

Objective : Although magnetic resonance guided focused ultrasound (MRgFUS) has been used as minimally invasive and effective neurosurgical treatment, it exhibits some limitations, mainly related to acoustic properties of the skull barrier. This study was undertaken to identify skull characteristics that contribute to optimal ultrasonic energy transmission for MRgFUS procedures. Methods : For ex vivo skull experiments, various acoustic fields were measured under different conditions, using five non-embalmed cadaver skulls. For clinical skull analyses, brain computed tomography data of 46 patients who underwent MRgFUS ablations (18 unilateral thalamotomy, nine unilateral pallidotomy, and 19 bilateral capsulotomy) were retrospectively reviewed. Patients' skull factors and sonication parameters were comparatively analyzed with respect to the cadaveric skulls. Results : Skull experiments identified three important factors related skull penetration of ultrasound, including skull density ratio (SDR), skull volume, and incidence angle of the acoustic rays against the skull surface. In clinical results, SDR and skull volume correlated with maximal temperature (Tmax) and energy requirement to achieve Tmax (p<0.05). In addition, considering the incidence angle determined by brain target location, less energy was required to reach Tmax in the central, rather than lateral targets particularly when compared between thalamotomy and capsulotomy (p<0.05). Conclusion : This study reconfirmed previously identified skull factors, including SDR and skull volume, for successful MRgFUS; it identified an additional factor, incidence angle of acoustic rays against the skull surface. To guarantee successful transcranial MRgFUS treatment without suffering these various skull issues, further technical improvements are required.

• Animal Systematics, Evolution and Diversity
• /
• v.37 no.3
• /
• pp.205-211
• /
• 2021

This study investigates the morphological and skull characteristics of the Siberian weasel Mustela sibirica quelpartis from the Jeju Island, South Korea. A total of 26 roadkill specimens (22 males and 4 females) were collected from October 2012 to April 2016. All collected specimens were examined for morphological characteristics, but only 19 specimens (16 males and 3 females) were in a good enough condition to process for skull measurements. This study showed no significant differences in ear length between male and female (p>0.05), and significant differences were found in head-body length, tail length (TL), and hind-food length (p<0.05). Both the male and female of M. s. quelpartis were larger in its external characteristics except for TL than M. s. coreanus living in the mainland of South Korea. M. s. quelpartis males have a smaller skull size than their female counterparts. In general, both male and female M. s. quelpartis showed external characteristics in line with the Island Rule. The findings of this study are important in order to shed more light on the evolutionary mechanism of small mammals living on the Jeju Island.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.13 no.2
• /
• pp.49-54
• /
• 2014

Skull Melted 3.2YSZ has good physical properties and does not undergo low temperature degradation. Due to these excellent physical and mechanical properties, Skull Melted 3.2YSZ has been studied for use in dental implants. In this study, a ø2.2mm Initial Twist Drill was made using Skull Melted 3.2YSZ; the drilling characteristics were compared with those of the traditional SUS420J drill. The experimental results indicate that the Skull Melted 3.2YSZ drill requires similar thrust forces and has a slightly higher temperature.

• Korean Journal of Veterinary Research
• /
• v.34 no.4
• /
• pp.705-714
• /
• 1994

This study was carried out to identify the craniometric characteristics of the skull of Korean native goat. The results were as follows; The skull index, cranial index, facial index, right orbital index and left orbital index were $55.86{\pm}2.14$, $59.97{\pm}3.68$, $107.03{\pm}5.71$, $92.22{\pm}4.54$and $90.47{\pm}5.48$, respectively. The ratio of facial length to cranial length was 1:1.15 and the ratio of length of cranial base to palatal length was 1:1.35. The skull length was more correlated to the facial length than to the cranial length(p<0.01). The skull width was more correlated to the width between foramina supraorbitales than to the width between foramina infraorbitales. It also showed negative correlation to the medial width between bases of processus cornualis but positive correlation to the lateral width between bases of processus cornualis(p<0.01). The width between tips of both horns showed high positive correlation to the medial width between processus cornualis, but negative correlation to the lateral width(p<0.01).

• Journal of Korean Neurosurgical Society
• /
• v.30 no.1
• /
• pp.54-59
• /
• 2001

Objectives : With the advancement of a social life, the pediatric head injuries(PHI) occur greater than ever. Since the PHI differs from adult head injury with regards to mechanism of trauma, prognosis, and mortality, it is important to identify the characteristics of the PHI for its proper treatments and prognosis. Methods : For this study, a series of 365 PHI patients under 15 years of age who were admitted to our hospital, were evaluated from January 1991 to December 1996. The clinical variable studied were age, sex, Glasgow coma score(GCS), causes of trauma, diagnosis, symptoms, associated injuries and Glasgow outcome score (GOS). The characteristics of PHI were evaluated according to presentations of skull fractures, intracranial hemorrhages, associated injuries, GCS at admission and GOS. Results : Mean age of the studied patients was 6.51 years of age. The majority of PHI patients were under the 7 years of age(66.7%). The ratio of male to female was 2.2:1. Seasonally, PHI occurred more frequently during March to August(61.6%). The main causes of the injuries were accidental falls and traffic accidents(47.1% and 46.3%). One hundred ninety seven(54%) patients suffered from skull fractures and 110(30.1%) patients were developed intracranial hemorrhages and acute epidural hematomas(17.8%) which were the most common intracranial hemorrhages. There was statistical significance between skull fractures and intracranial hemorrhage (p=0.032) and between GCS and GOS(p=0.001). However, there was no statistical significance between skull fractures and intracranial hemorrhage(epidural hematomas, subdural hematomas, and intracerebral, intraventricular and subarachnoid hemorrhage)(p=0.061, 0.251 and 0.880). Also there were no significance of prognosis between under the seven and over the 8 years of age(p=0.349). Conclusions : The core management for PHI is prevention from its occurrences. However, when unexpected accident occurs, early diagnosis and treatment for PHI by through examination for associated injuries and other damages even if there is no skull fracture are essential in managing patient's outcome.

• Korean Journal of Materials Research
• /
• v.19 no.2
• /
• pp.115-118
• /
• 2009

The use of dolomite refractories has increased during the past several years in the manufacturing of clean steel during the stainless steelmaking process. However, at the same time, the use of dolomite refractories has led to what is known as the skull formation. In the present work, to understand the skull formation, the wetting characteristics of dolomite substrates by liquid Fe-19wt%Cr-10wt%Ni alloys in various oxygen partial pressures were initially investigated at 1753K using the sessile drop technique. For comparison, the wetting characteristics of alumina substrates were investigated with the same technique. It was found that the wetting index, (1+$cos{\theta}$), of dolomite is approximately 40% higher compared to those of alumina. In addition, the oxygen partial pressure to generate the surface oxide, which may capture the liquid metal on the refractory surface, for dolomite is much lower than that for alumina. From this study, it was concluded that the use of dolomite is much more closely associated with the skull formation compared to the use of alumina due to the stronger wettability and the surface oxide formation at a lower oxygen partial pressure of dolomite.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.13 no.1
• /
• pp.72-77
• /
• 2014

3.2YSZ melted by the 'skull melting' method has good physical properties and does not undergo low-temperature degradation. Due to its excellent physical and mechanical properties, skull-melted 3.2YSZ has been developed as a dental implant material. In this study, a porous, resin-bonded diamond wheel was created and its grinding characteristics were compared with those of traditional nonporous wheels using skull-melted 3.2YSZ. The experimental results indicate that the porous, resin-bonded diamond wheel requires less grinding force and power. In addition, the porous, resin-bonded diamond wheel requires a greater degree of roughness.

• Journal of the Korean Society of Radiology
• /
• v.13 no.5
• /
• pp.765-771
• /
• 2019

Noise in skull X-ray imaging is inevitable, which reduces imaging quality and diagnostic accuracy and increases errors due to the nature of digital imaging devices. Increasing the dose can attenuate noise, but that could lead to big problems with higher exposure dose received by patients. Thus, noise reduction algorithms are actively being studied at low doses to solve dose problems and reduce noise at the same time. Wiener filter and median filter have been widely used, with the disadvantages of poor noise reduction efficiency and loss of much information about imaging boundary. The purpose of this study is to apply total variation (TV) algorithm to skull X-ray imaging that can compensate for the problems of previous noise reduction efficiency to assess quantitatively and compare them. For this study, skull X-ray imaging is obtained using various kVp and mAs using the skull phantom using the X-ray device of Siemens. In addition, contrast to noise ratio (CNR) and coefficient of variation (COV) are compared and measured when noisy image, median filter, Wiener filter and TV algorithm were applied to each phantom imaging. Experiments showed that when TV algorithms were applied, CNR and COV characteristics were excellent under all conditions. In conclusion, we've been able to see if we can use TV algorithm to improve image quality and CNR could be seen to increase due to the decrease in noise as the amount of increased mAs. On the other hand, COV decreased as the amount of increased mAs, and when kVp increased, noise was reduced and the transmittance was increased, so COV was reduced.

• Journal of Korean Neurosurgical Society
• /
• v.30 no.1
• /
• pp.89-94
• /
• 2001

Skull or brain metastasis from thyroid carcinoma is rare. Between Jan. 1993. and Jan. 2000. the authors experienced 7 cases of skull(4 cases) or brain(3 cases) metastasis from thyroid carcinoma. Clinical characteristics, radiologic findings and pathologic features were analyzed retrospectively. Among 4 cases of skull metastasis, 3 cases were follicular carcinoma and one was papillary carcinoma with follicular variant. All cases of brain metastasis were papillary carcinoma. We treated the patients by combination with surgical resection, radioactive iodine therapy and radiation therapy. Characteristics of skull or brain metastasis from thyroid carcinoma is reviewed with a pertinent literature.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.16 no.4
• /
• pp.141-148
• /
• 2006

Skull melting method can be a good candidate for growing oxide single crystals with high quality and for mass production because of its low production costs and high yield through recycling of crust. In this study, rutile single crystals were frown by the skull melting method and ingot characteristics with the variation of different growth conditions has been investigated. Conditions for high quality rutile ingot growth were used for producing cold-crucible size of ${\Phi}12cm{\times}H14cm$, capacity of 3000 pF tank condenser, work frequency of 2.84 MHz, melt-dwelling time of 9hrs and growing speed of 2 mm/h.