• Proceedings of the KIEE Conference
• /
• 1998.07e
• /
• pp.1656-1658
• /
• 1998

This paper deals with a measurement system of a distance between lightning strokes and observatory station and spectrum analysis of electric fields radiated from lightning discharges. The distance measurement system, which consists of a loop type magnetic field sensor, a microphone and one chip microprocessor, is connected to a personal computer through RS232 port to acquire and process the data. This system is to use a difference of propagation velocity between an electromagnetic wave and a sonic wave produced by lightning discharge. Also, an electric field waveform and a frequency spectrum were investigated by an electric field measurement system with a hemisphere antenna and a spectrum analyzer with a biconical antenna and a log-periodic antenna, respectively. The results would be used as a basic reference to protect the power systems and electric circuits from lightning overvoltages.

• Investigative Magnetic Resonance Imaging
• /
• v.19 no.4
• /
• pp.248-251
• /
• 2015

Hemangioblastomas are angioblastic tumors of the central nervous system. Cerebellar hemangioblastomas are traditionally classified into two morphologic types-cystic and solid. Cystic hemangioblastomas are associated with peritumoral edema, but solid hemangioblastomas are not. We report a case of solid cerebellar hemangioblastoma with massive peritumoral edema. An 83-year-old female visited our hospital due to a sudden headache. Five years ago, she had been admitted to our hospital with similar headache and diagnosed with cerebellar hemangioblastoma. Follow-up brain MRI 5 years later showed an increased size of a homogeneous enhancing mass with aggravated peritumoral edema in the left lower cerebellar hemisphere. Cerebral angiography showed a highly vascularized mass in the cerebellum, which was compatible with a solid-type hemangioblastoma.

• Journal of Korean Neurosurgical Society
• /
• v.39 no.4
• /
• pp.300-302
• /
• 2006

"Stunning" represents prolonged contractile depression of any muscular component after alleviation of severe ischemia, as shown in reperfusion following acute myocardial ischemia or ischemic stroke. Clinically, it presents with no or delayed recovery past to thrombolytic therapy but its pathogenic mechanism is not fully uncovered yet. We describe a unique case of a 63-year-old woman, who was undertaken endovascular coiling for the aneurysms, deteriorated several hours later without known cause, and showed delayed clinical improvement over the next 3 days following thrombolysis. Immediate post-thrombolysis magnetic resonance imaging scan showed no apparent abnormality except for high signal intensity within the corresponding hemisphere. Reversible but delayed nature of " brain stunning" can be explained by these images and it seems to be caused by a certain type of reperfusion injury.

• Proceedings of the KIEE Conference
• /
• 1996.07c
• /
• pp.1867-1869
• /
• 1996

In this paper, in order to obtain the statistic information for parameters of electric and magnetic field waveforms associated with lightning discharges, the electric and magnetic fields produced by lightning discharges in the summer of 1995 were measured by a hemisphere-type electric field sensor and a loop-type magnetic field sensor, which were installed at the campus of Inha University in Inchon. The signals of the electric and magnetic fields were continuously recorded by a transient digitizer having a resolution of 12 bit and a memory capacity of 5000 point. Negative lightning discharges are produced very more than positive lightning discharges in the summer of Korea. The 10 to 90 % rise time of electric and magnetic fields was 2 $2\;{\sim}\;10\;{\mu}s$. And the zero-crossing time of electric field was $15\;{\sim}\;25\;{\mu}s$, whereas that of magnetic field was $20\;{\sim}\;30\;{\mu}s$.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.11 no.6
• /
• pp.1006-1014
• /
• 2000

Hemisphere type Luneberg lens antenna with a reflector(frequency : 9.375 GHz, -3 dB beam width 6$^{\circ}$, diameter 30.3 cm(about 10 A), which is miniaturized and lightweightized by attaching a reflector on a section of half the Luneberg lens antenna, is designed and fabricated on the basis of Luneberg lens antenna from which easy beam pointing is acquired only by movement of 1st radiator. Measurement shows -3dB beamwidth is 6.1$^{\circ}$ in case of E-plane and 5.5$^{\circ}$ in case of H-plane. These are good agreements with expected value. Gain of this antenna is 26dBi(Aperture efficiency for uniform distribution : $\pi$ = 44.97%) which is greater than that of 1st radiator(Rectangular microstrip antenna) by 20.4 dB. And, after calculating the approximated pattern of the 1st radiator, far-field pattern, whose source is the second aperture source farmed from the approximated pattern of the 1st radiator is computed. Comparing this far-field pattern with the expected pattern, a (relatively) good agreement is observed. Circular polarization Luneberg lens antenna is also manufactured by making 1st radiator so that it has the characteristics of LHCP and RHCP radiation. The results are as followings : -3 dB beamwidth 5.8$^{\circ}$ , side lobe level -15.3 dB, isolation between LHCP and RHCP radiation 2543, axial ratio 2 dB bandwidth about 1.4 GHz(14.9%).

• Journal of Korean Neurosurgical Society
• /
• v.54 no.5
• /
• pp.405-410
• /
• 2013

Objective : The objective of this study was to investigate changes in the posterior cranial fossa in patients with symptomatic Chiari malformation type I (CMI) compared to a control group. Methods : We retrospectively reviewed clinical and radiological data from 12 symptomatic patients with CMI and 24 healthy control subjects. The structures of the brain and skull base were investigated using magnetic resonance imaging. Results : The length of the clivus had significantly decreased in the CMI group than in the control group (p=0.000). The angle between the clivus and the McRae line (p<0.024), as the angle between the supraocciput and the McRae line (p<0.021), and the angle between the tentorium and a line connecting the internal occipital protuberance to the opisthion (p<0.009) were significantly larger in the CMI group than in the control group. The mean vertical length of the cerebellar hemisphere (p<0.003) and the mean length of the coronal and sagittal superoinferior aspects of the cerebellum (p<0.05) were longer in the CMI group than in the control group, while the mean length of the axial anteroposterior aspect of the cerebellum (p<0.001) was significantly shorter in the CMI group relative to control subjects. Conclusion : We elucidate the transformation of the posterior cranial fossa into the narrow funnel shape. The sufficient cephalocaudal extension of the craniectomy of the posterior cranial fossa has more decompression effect than other type extension of the craniectomy in CMI patients.

• Journal of Fashion Business
• /
• v.14 no.1
• /
• pp.57-75
• /
• 2010

This study is done in Shanghai area by sample survey of female college students in their lower 20s. Through direct contact survey, this study collected and analyzed information on figure to understand feature of breasts and measurements of body to provide base information to improve product of brassiere for adult female in China. Data was analyzed by using SPSSWIN 13.0 Program and SAS 9.0. 1. From a result of factor analysis on 40 items of measures to derive the components of the shape of the breast, 6 factors were derived such as the factors to show the obesity of the bust, to show the ratio of the upper and lower area of the lower bust, droop and volume, to show the internal shape and broadness of the bust, to show the location and vertical size of the bust, to show the protrusion of the bust and the eternal shape of the bust. 2. From a result of classification on the shape of the breast of the Chinese women in their early 20s, 4 types were selected. Type 1 is the protrusion type that a woman has a broad drooped breast due to the development in the upper and lower parts of the chest as well as the highest height, a high degree of obesity in the bust part, big volume and much protrusion. Type 2 is the hemisphere type that the degree of obesity in the breast is second to Type 1 and a breast is located at a region higher than Type 1 as the degree of obesity in the breast is secondly highest, the lower part of the bust is bigger than the Type 1 and the degree of being broad and drooped is second to Type 1. Type 3 is the cone type with a breast of being drooped and broad a little bit and a certain degree of a volume. Type 4 is the flat type with the smallest value in the item that shows the obesity of the bust area and with the smallest value in the R$\ddot{o}$hrer index to have the small and slender body type for the bust area, which is somewhat flat due to a low slope at the internal side of the bust.

• Atmosphere
• /
• v.33 no.1
• /
• pp.49-59
• /
• 2023

Blocking refers to a class of weather phenomena appearing in the mid and high latitudes, whose characteristics are blocked airflow of persistence. Frequently found over the Pacific and Atlantic regions of the Northern Hemisphere, blocking affects severe weather in the surrounding areas with different mechanisms depending on the type of blocking patterns. Along with lots of studies about persistent weather extremes focusing on the specific types of blocking, a new categorization using Rossby wave breaking has emerged. This study aims to apply this concept to the classification of blockings over the Pacific and examine how different wave breakings specify the associated cold weather in the Korean peninsula. At the same time, we investigate a strongly developing ridge around the Pacific by designing a new detection algorithm, where a reversal method is modified to distinguish ridge-type blocking patterns. As result, Kamchatka blocking (KB) and strong ridge over the Central Pacific are observed the most frequently during 20 years (2001~2020) of the studied period, and anomalous low pressures with cold air over the Korean Peninsula are accompanied by blocking events. When it considers the Rossby wave breaking, cyclonic wave-breaking is dominant in KB, which generates low-pressure anomalies over the Korean Peninsula. However, KB with anticyclone wave breaking appears with the high-pressure anomalies over the Korean Peninsula and it generates the warm temperature anomaly. Lastly, the low-pressure anomalies are also generated by the strong ridge over the Central Pacific, which persists for approximately three days and give a significant impact on cold surge on the Korean Peninsula.

• The Research Journal of the Costume Culture
• /
• v.14 no.5
• /
• pp.840-849
• /
• 2006

Breast volume has been approximately estimated under the assumption that the shape of breast is a corn. However, women's breast is more like a bulged bag in reality. In this paper, three methods of breast volume estimation were compared to find out the more accurate method. The shape of the breast is assumed as a hemisphere in the first estimation method and a corn in the second one. In the third method, arc along the cross sectional shape of breast was utilized in the calculation. Comparisons among the methods were made using the actual 3D volume measurement of thirty seven women's breast. As results, the third method was the best one for the normal breast type, especially for the lower part of the breast ($R^2=0.74$) which is the crucial design parameter of the brassiere. Assumption of the shape of breast as a corn was reasonably acceptable when the breast is sagged. It was expected that when women wore brassiere, the accuracy of the third method would increase more, since the shape of breast becomes more symmetrical.

• Journal of Korean Neurosurgical Society
• /
• v.42 no.2
• /
• pp.149-152
• /
• 2007

Authors report a very rare case of primary Hodgkin's lymphoma limited to the cerebellum. A 64-year-old female patient presented with headache, nausea, and vomiting. Magnetic resonance imaging of the brain revealed a nodular enhancing mass in the left cerebellar hemisphere. Tumor was removed totally with retromastoid suboccipital approach. Diagnosis was Hodgkin's lymphoma of mixed cellularity type, consisting of a dense mixed inflammatory infiltrate containing scattered large atypical mononuclear Hodgkin's cell and multinucleated Reed-Sternberg cells. Systemic work-up for the Hodgkin's lymphoma was followed with negative result. Postoperative radiation therapy was given and the patient is disease-free at 16 months after the operation.