• Structural Engineering and Mechanics
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• v.28 no.3
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• pp.335-352
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• 2008

Continuous operation of test and measurement is a new operating technique in the petroleum exploitation, which combines perforation with test and measurement effectively. In order to measure the original pressure of stratum layer exactly and prevent testing instrument from being impaired or damaged, a suitable shock absorber is urgently necessary to research. Based on the attempt on the FEM analysis and experiment research, a new shock absorber is designed and discussed in this paper. 3D finite element model is established and simulated accurately by LS-DYNA, the effect and the dynamic character of the shock absorber impact by half sinusoidal pulse force under the main lobe frequency are discussed both on theoretics and experiment. It is shown that the new designed shock absorber system has good capability of shock absorption for the impact load.

• Clinical and Experimental Pediatrics
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• v.50 no.8
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• pp.726-731
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• 2007

This review describes the wide spectrum of paroxysmal events during sleep in infancy and childhood. The differential diagnosis between sleep-related non-epileptic paroxysmal events and epileptic seizures is difficult in special occasions. The nocturnal frontal lobe seizure and of the more common nonepileptic paroxysmal events during sleep are described. The main differentiating features characterizing parasomnias are: onset in early childhood, rare episodes of long duration, relatively lower frequency per night, absence of stereotypy, gradual disappearance of older age. Video-polysomnography is the gold standard to diagnosing and differentiating parasomnias from nocturnal frontal lobe seizures.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.4
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• pp.637-642
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• 2020

In this study, the SLB(Sidelobe Blanking)/BLB(Blacklobe Blanking) design of the VHF band radar using the low-frequency band having a relatively larger beam width than the S-band or X-band radar. The antenna of the VHF band has a relatively large beam width, so it is reflected from the side lobe. If the reflected target signal is not processed into sidelobe, the false alarm rate of the radar increases by recognizing it from the main lobe signal. This method of SLB blocking is the elimination of the side lobe signal in the front of the array antenna using the central radiating element of the array antenna, and the blocking of side lobe signal from the antenna rear through BLB receiver block. After completed the radar implementation, The function of blocking of side lobe signals was confirmed through the system unit test by Simulated signal generator. Through this study, it will be used in the implementation of the side-lobe blocking technology of the array antenna for low-frequency band radar with large antenna size and beam width in the future.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.04a
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• pp.816-820
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• 2011

A method for increasing the difference of side-lobe level in spherical microphone array is presented. In array signal processing, it is known that narrow interval between sensors can increase the difference between main lobe and side-lobe of array response which eventually increase the source recognition capability. Recent commercial array being used, however, have shown certain limitation in using the number of sensors due to its costs and geometrical size of array. To overcome this problem, we have adapted MEMS sensors into spherical microphone array. To check out the improvement, two different types of spherical microphone array were designed. One array is composed with 32 regular instrument microphones and the other one is 85 MEMS sensors. Simulation and experiments were conducted on a sinusoidal noise source with two arrays. The time history data were analyzed with spherical harmonic decomposition and beamforming technique. 85 MEMS sensors array showed the improved side-lobe level suppression by more than 4 dB above the frequency content of 2 kHz compared to 32-sensor array.

• Journal of the Optical Society of Korea
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• v.18 no.5
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• pp.449-452
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• 2014

We present a multi-tap microwave photonic filter with high selectivity through applying time-to-frequency mapping and optical frequency comb shaping techniques. When arranged in the time-to-frequency mapping stage, by a Fourier transform, the deviation of the optical taps to the target profile is significantly reduced while maintaining the apodization profile, resulting in high sidelobe suppression in the filters. By applying a simple time-to-frequency mapping stage to the conventional optical frequency combs, we demonstrate a substantially enhanced (>10dB) sidelobe suppression, resulting in filter lineshapes exhibiting a significantly high (>40dB) main lobe to sidelobe suppression ratio. These results highlight the potential of the technique for implementation in various passband filters with high sidelobe suppression.

• The Journal of the Acoustical Society of Korea
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• v.15 no.1
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• pp.71-80
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• 1996

Characteristics of sleeve-gun arrays installed on the R/V Onnuri were analyzed and compared with survey data. In the case of cluster array, the beam width in the frequency range up to 814Hz is constant as $179.5^{\circ}$, and rapidly narrows in the frequency range of 814-1631Hz. However, in the case of long and wide arrays, as the frequency increases, the beamwidth decreases. The optimal frequency is 69Hz. the main lobe of vertical inclination has its maximum amplitude at phase angle $0^{\circ}$. The optimal frequency of cluster array which produces little side lobe is less than 1631Hz, and those of long and wide arrays are less than 108Hz. As a result, the cluster array produces a good source for high-resolution seismic survey, while the long and wide arrays are suitable for the survey of deep structures. The final high-resolution seismic section with cluster array was compared with that of long and wide arrays.

• The Journal of the Acoustical Society of Korea
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• v.35 no.6
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• pp.452-465
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• 2016

In this study, the structure of a concave annular array transducer was optimized to generate high intensity focused ultrasound for medical therapeutic application. The transducer has a phased array structure composed of several concentric channels that have 40 mm as the radius of curvature. We derived theoretical equations to analyze the sound field of the transducer and verified the validity of the equations by comparing the results calculated by the equations with those from finite element analyses. We also checked the possibility of dynamic focusing at around the geometric focal point. Further, the level of a grating lobe occurring at an unwanted position in the transducer sound field was confirmed to be reducible through the relation between the number of channels and the frequency of the transducer. Hence, the structure of the transducer was optimized to place the main lobe within a specific range from the zenith while systematically reducing the level of the maximum sidelobe including the grating lobe. The designed structure showed the performance better than that targeted at all the focal points.

• Journal of radiological science and technology
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• v.6 no.1
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• pp.91-102
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• 1983

The study was carried out on 468 cases among total 4,347 cancer cases which was confirmly diagnosed as malignant neoplasms at Yonsei Center Hospital, appended to Yonsei University, during 10 years from January 1, 1971 to December 31, 1980. The results of this study are as follows: 1. Total malignant neoplasm cases treated with radiation were 4,347, 1,685 of whom were males, and 2,662 females(male to female ratio was 1:1.58). 2. Lung cancer were 10.8% of total malignant neoplasm cases(468 cases), 391 cases for the male and 77 cases for the female. So, average the male to female ratio was 8:1 and cases of the male were much more. 3. The age distribution of lung cancer cases was from 27 to 82 years old. The highest age distribution was $50{\sim}59$ for males(37.9%) and $60{\sim}69$ for females(41.6%) ; 77.1% of total lung cancer cases were over 50 years old. 4. In regard to stages, the distribution of the third stage was highest(49.3%). That of the first stage was much higher during the last period(11.8%) than the first period(2.7%), and that of the fourth stage was much lower during the last period (7.8%) than the first period(21.1%). 5. In regard to pathological type, the distribution was 51.3% for squamous cell carcinoma, 29.3% for undifferentiated cell cercinoma, 12.2% for adenocarcinoma, and 7.2% for bronchoalveolar cell carcinoma in order of frequency. In regard to adenocarcinoma, the male to female ratio was 1:3.7 and cases of the female were much more. 6. In regard to tumor location, the distribution of tumor location in the right-left lobe was 59.1% in the right lobe, 33.6% in the left lobe, and 7.3% in the both lobes in order of frequency. And that of tumor location in the upper and lower lobes was all higher in the upper lobe ; especially, that of the right upper lobe was highest(31.2% of total cases). 7. For the main symptom, coughing was highest(64%), 50% for hemoptysis, and 41% for dyspnea.

• Proceedings of the KOR-BRONCHOESO Conference
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• 1978.06a
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• pp.5.1-5
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• 1978

Since Ikeda in traduced flexible fiberoptic bronchoscope in 1968, use of bronchoscopy was expanded rapidly. Wide use of flexible bronchoscopy enabled us to get tissue diagnosis with more ease and safety. Authors analyzed 71 cases of tissue biopsy of 233 bronchoscopies from June '76 to. Jan. '78 and concluded as following : 1. 233 bronchoscopies af 20 Month duration, cases which needed tissue biopsy were 71 cases (30.5%). 2. Chief complaints af above cases are coughing, dyspnea, sputum, chest pain, hemoptysis in frequency. 3. Biopsy sites were as following in frequency: Rt.upper lobe, Lt. main bronchus, Lt. upper lobe, Rt. main bronchus, Lt. lower lobe. 4. The final diagnosis of biopsied cases were cancer 80%, tuberculosis 15%, and malignant mesothelioma, anthracosis, aspergillosis, were one case each. 5. Among 57 case of lung cancer, biopsy confirmed cases were 36 cases (63%). 6. Pathologic finding of 36 case of Biopsy confirmed lung cancer was as following: Squamous cell ca : 64% Anaplastic ca : 25% Adeno ca : 2.8% Unclassified: 2.8% 7. Bronchographies were done in 36cases (51%), one quarter of cases before biopsy, and three quarters of cases after biopsy. 8. Cytology was requested in 76% of cases with following results; PAP class V 15%, class IV 7.5%, class III 1.8%.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.10
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• pp.31-38
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• 1994

In this paper, the leaky wave readiation characteristics of a microstrip rectangular patch array is presented. The reflection and transmission characteristics are analyzed using the equivalent transmission line method. Since the leaky wave is generated from the periodic array, using the Floquet'theorem, leaky wave frequency range is predicted and confirmed by the measured reflection and transmission characterstics of the array. A 17 element microstrip patch array at X-Band is designed and tested. Teh scattering Characteristics show good agreement woth those obtained from the equivalent transmission line analysis. The radiatio characteristics at 10GHz using this method show about 3${\circ}$ shift in main lobe angle compared with measured results.