• Journal of the Korea Institute of Military Science and Technology
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• v.16 no.3
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• pp.373-381
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• 2013

In this paper, the effects of phase noise on the radar system were analyzed in terms of 3 point of view. The impact(s) on the compressed pulse waveform, the FMICW(Frequency Modulated Interrupted Continuous Wave) radar performance and the receiver sensitivity were investigated. From the investigation, it was indicated that the phase noise over 10 kHz offset frequency makes the side lobe level of compressed pulse worse. Also it was founded that the FMICW radar performance, especially at the noise level of range profile, is related to the phase noise. Finally, the investigation showed that the phase noise at local oscillator affects the receiver sensitivity.

• Korean Journal of Remote Sensing
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• v.33 no.4
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• pp.437-444
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• 2017

Since land pixels often generate false alarms in ship detection using Synthetic Aperture Radar (SAR), land masking is a necessary step which can be processed by a land area map or water database. However, due to the continuous coastline changes caused by newport, bridge, etc., an updated data should be considered to mask either the land or the oceanic part of SAR. Furthermore, coastal concrete facilities make noise signals, mainly caused by side lobe effect. In this paper, we propose two methods. One is a semi-automatic water body data generation method that consists of terrain correction, thresholding, and median filter. Another is a dynamic land masking method based on water database. Based on water database, it uses a breadth-first search algorithm to find and mask noise signals from coastal concrete facilities. We verified our methods using Sentinel-1 SAR data. The result shows that proposed methods remove maximum 84.42% of false alarms.

• Journal of Korean Neurosurgical Society
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• v.42 no.5
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• pp.410-412
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• 2007

Pleomorphic xanthoastrocytoma (PXA) has been considered as a low grade tumor of adolescents and young adults. Although this tumor often shows cystic component, the hemorrhage within the cyst is extremely rare. The authors report a rare case of cystic PXA with a hemorrhage within the cyst and the mural nodule in the left frontal lobe. A 64-year-old male presented with a week history of the right side hemiparesis. After gross total resection of the tumor, the patient was fully recovered from neurological deficit. It is suggested that this typically benign tumor could be presented with hemorrhage, causing a rapid neurological deterioration. Prompt surgical intervention, especially total removal of the tumor can provide an excellent functional recovery.

• Journal of Korean Neurosurgical Society
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• v.40 no.2
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• pp.131-134
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• 2006

The cerebral vasospasm after clipping surgery of unruptured aneurysm is uncommon. A 44-year-old man with unruptured left middle cerebral artery[MCA] aneurysm had clipping surgery. From the third postoperative day, he presented with drowsy mentality, dysphasia and right hemiparesis. Computed tomographic scans showed low density area in frontotemporal lobe and midline shift. Transfemoral cerebral angiography revealed severe vasospasm in supraclinoid internal carotid artery, anterior cerebral artery, and MCA on the operative side. We performed left frontotemporoparietal craniectomy and hypertensive-hypervolemic therapy. He recovered without neurological deficits but for dysphasia. Neurosurgeon should be alert to the possibility of vasospasm after clipping surgery even in case of unruptured cerebral aneurysm.

• Journal of Veterinary Clinics
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• v.16 no.2
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• pp.478-481
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• 1999

A 8 years old male Pomeranian weighing 4 kg was referred because of coughing of 4 months' duration. Heart sounds and cardiac apex beat were showed more intense on the right side. On radiographic views, loss of normal line of the diaphragm, gas-containing intestines and stomach in thoracic cavity, and right displacement of heart were observed. Ultrasonography revealed that liver located adjacent to the heart. Although the dog died due to severe respiratory disorder in surgical procedure, in thoracic and abdominal surgery, a large defect was found in the left and right ventral muscular portion and left central tendon of the diaphragm, extending from the esophageal hiatus to rib. Left and right cranial lobe of liver, small intestines, stomach and spleen were herniated in the thoracic cavity. Because of the size and chronicity of the defect in the diaphragm, closure was impossible with an abdominal muscle graft.

• Journal of electromagnetic engineering and science
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• v.2 no.1
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• pp.28-33
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• 2002

The LHCP circularly polarized antenna operating at DBS band is developed by employing the sequential-rotation technique in which each subarray is comprised the three truncated-corner patch square element. Antenna designed with sequentially-related technique whose M=3, p=2 has the effect of improved axial-ratio bandwidth, cross-polarization etc. And it is proved that the degradation of radiation pattern can be reduced significantly by minimizing the radiation loss of feeding line structure. Antenna designed shows extremely low side lobe level of below - 25 dB in the diagonal plane and cross-polarization level of below -20 dB in the all plane. And these performances comply with the array antenna specification for DBS.

• Proceedings of the IEEK Conference
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• 2002.07b
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• pp.723-726
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• 2002

This paper describes the design, fabrication, and measurement of a sequential-rotation microstrip-array antenna for the Electronic Toll Collection System (ETCS). The ETCS is made possible by using roadside equipment with radiation pattern that can accurately pinpoint the designated communication area, without interference from other lanes. The sequential-rotation microstrip-array antenna was applied to the absorber to reduce the side lobe level (SLL). Results showed that the antenna yields a return loss at a center frequency of -20.675 dB, an axial ratio of 1.15 dB, and a gain of 20.26 dBi.

• ETRI Journal
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• v.29 no.4
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• pp.452-456
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• 2007

Very compact 4-channel 200-GHz-spacing external cavity lasers (ECLs) were fabricated by hybrid integration of reflection gratings and superluminescent laser diodes on a planar lightwave circuit chip. The fifth-order gratings as reflection gratings were formed using a conventional contact-mask photo-lithography process to achieve low-cost fabrication. The lasing wavelength of the fabricated ECLs matched the ITU grid with an accuracy of ${\pm}0.1$ nm, and optical powers were more than 0.4 mW at the injection current of 80 mA for all channels. The ECLs showed single mode operations with more than 30 dB side lobe suppression.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.964-967
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• 2001

Aspherical lens with the higher numerical aperture has been needed in the optical storage device to increase the recording density on the disk. However, high numerical aperture means the large slope angle at the clear aperture of the lens. Therefore, the measurement and manufacturing technique including the lens molding process for the slope angle should be developed. In this paper, the evaluation technique was described for the optical performance of the aspherical lens. Aspherical form error brings about the wavefront error and the side lobe of the beam intensity profile. A schematic diagram of the aspherical lens manufacturing was drawn to explain the aspherical form error compensation. Finally, form error of the aspherical lens was defined and plotted using the raw data of the Formtalysurf.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.1
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• pp.57.1-57.1
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• 2017

As an upgrade we report the current ASTE ultra-wideband corrugated horn design. The length of the feedhorn gets shortened from 12.5 mm to 11 mm, and it shows better side lobe level at the far-field patterns compared with the previous design. We looked into possible quasi-optical solution to match the feedhorn beam to the optics of the current ASTE telescope, starting from frequency-independent solution using two ellipsoidal mirrors to which wideband performance of the feedhorn naturally fits. We used a commercial physical optics package (GRASP) with an user-defined optimizer to give physical constraints to evaluated optical designs for highest efficiency.