• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1991.04a
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• pp.17-22
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• 1991

최근 기계장치로부터 발생하는 소음을 감소시키는 새로운 방법으로서, 능동 적으로 소음을 제어하는 방법에 대한 연구가 활발히 진행되고 있다. 이것은 원하지 않는 소음을 그 신호의 역위상을 갖는 부가음을 이용하여 능동적으 로 감쇠시키는 방법으로서, 저주파수 대역에서 비효율적인 수동적인 방법인 소음기둥에 대한 대안으로 많은 학자들의 관심의 대상이 되어 왔다. 초기에 는 소음을 줄이기 위해 요구되는 여러가지 음향요소의 전달함수를 제어하는 데 대한 불가능성으로 인해 능동 소음제어에 대한 실질적인 발전이 지연되 어 왔으나 최근 마이크로 컴퓨터를 비롯한 전자공학의 발전으로 인해 적응 신호처리 분야가 등장하게 되었으며, 음향계의 소음을 원하는 수준까지 제어 하는 능동 소음제어의 실시간 구현이 가능하게 되었다. 그 중에서도 음이 1 차원적으로 전파한다고 볼 수 있는 길이가 긴 덕트구조물에서의 능동 소음 제어는 가장 기본적이며 현실적으로 자동차 배기계나 냉동.공조설비에 있어 서 실용적으로 적용할 수 있는 문제임 만큼 많은 연구가 이루어지고 있다. 이러한 능동 소음제어 방법을 음향계에 적용하였을 때, 부가적인 음을 발생 하는 제어용 스피커로 인해 입력마이크로폰으로의 음향궤환이 존재하고 이 에 따라 제어계가 불안정해질 수 있으며, 또한 변환기의 사용으로 인한 부가 적인 전달함수가 존재하므로 이에 대한 중요한 의미를 갖고 고려하여야 한 다. 본 연구에서는 적응 필터링 이론에 의한 소음원의 입력신호에 대한 최적 한 예측으로써 부가음을 발생시키고, 입력신호 및 제어된 출력신호간의 차인 오차를 최소화 시키도록 하는 오차적응제어법을 이용한 능동소음 제어 방법 을 제시하였다. 이와 아울러 제어계의 환경변화에 따른 파라메타의 변화에 적응적으로 응답이 가능해야 하는 적응 소음제어 시스템에서, 음향궤환과 함 께 필히 고려해야 하는 부가적인 전달함수의 영향을 고려한 능동 소음제어 에 대해 연구하였다. 경량화 추세에 따라 지반이나 케이싱이 경량이거나 유연하여 회전축과 동적으로 연성된 경우 회전축-베어링-지반으로 이루어진 2중구조의 회전축 계 동특성을 해석할 수 있는 프로그램을 개발하므로서 회전 기계류의 진동 전반에 걸친 문제점에 대한 그 원인과 현상을 명확히 분석하여 국내의 전기 계류의 보다 신뢰성있는 설계 및 제작자료를 확보하는데 기여할 수 있게 하 였다.존의 small molecular Gd-chelate에 비해 매우 큼을 알 수 있었다. MnPC는 간세포에 흡수된 후 담도계로 배출되는 간특이성 조영제임을 확인하였다. 장비 내에서 반복 시행한 평균값의 차이는 대체적으로 유의한 차이가 없었으나, 다른 장비에서 반복 시행한 장비간의 사이에는 유의한 차이가 있는 경우가 더 많았다. 따라서 , MRS 검사를 소뇌나 뇌교의 어떤 절환에 적용하기 전에 각 장비 마다 정상 기준치를 반드시 얻은 후에 이상여부를 판 정하는 것이 필수적이라고 생각된다.EX> 이상이 적절한 진단기준으로 생각되었다. $0.4{\;}\textrm{cm}^3$ 이상의 좌우 부피차를 보이는 모든 증례에서 육안적으로도 해마위축이 뚜렷이 나타났다. 결론 : MR영상을 이용한 해마의 부피측정은 해마경화증 환자의 진단에 있어 육안적인 MR 진단이 어려운 제한된 경우에만 실제적 도움을 줄 수 있는 보조적인 방법으로 생각된다.ofile whereas relaxivity at high field is not affected by τS. On the other hand, the change in τV does not affect low field profile but strongly in fluences on both inflection fie이 and the maximum relaxivity value. The results shows a fluences on both inflection field

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.6
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• pp.1506-1514
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• 2015

In this paper, we proposed a forest fires prediction and detection system. It could provide a situation of fire prediction and detection methods using context awareness sensor. A fire occurs wide range of sensing a fire in a single camera sensor, it is difficult to detect the occurrence of a fire. In this paper, we propose an algorithm for real-time by using a temperature sensor, humidity, Co2, the flame presence information acquired and comparing the data based on multiple conditions, analyze and determine the weighting according to fire in complex situations. In addition, it is possible to differential management of intensive fire detection and prediction for required dividing the state of fire zone. Therefore we propose an algorithm to determine the prediction and detection from the fire parameters as an temperature, humidity, Co2 and the flame in real-time by using a context awareness sensor and also suggest algorithm that provide the path of fire diffusion and service the secure safety zone prediction.

• The Journal of the Korea Contents Association
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• v.7 no.4
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• pp.234-240
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• 2007

The purpose of this paper was to architecture optimal model of the scooped swing in high bar. The scooped swing was modeled to the double pendulum and was simulated with the Lagrange's equation of motion. Lagrange's method based on a energy approaching method was implemented as a equation of motion. The subject was a national man-gymnast(age 18yrs, height 153 cut mass 48 kg) and the high bar of SPIETH company was used to measure the scooped swing. Qualisys system(six MCU-240 cameras, QTM software)was used to capture data for imaging analysis. The solution of a model and data processing were solved in Mathematica5.0. The results were as follows: First model value of maximum bar displacement was longer than experimental value, that is, 0.02 m. Second, both angular pattern of segment1(HAT) had a increasing curve but curve patterns had a different concave and convex me. Third the experimental value of maximum angular angle of segment2(total leg) had larger than model value, that is, $4^{\circ}$. Conclusively, model parameters were quasi-optimized to obtain a quasi-match between simulated and actual performances. It hopes to simulate a human model by means of integrating musculoskeletal and neuromuscular system in the future study.

• Journal of the Korean Association of Geographic Information Studies
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• v.9 no.3
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• pp.146-155
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• 2006

A handful of previous studies have attempted to integrate socioeconomic data and remotely sensed data for urban quality of life assessment with their spatial dimension in a zonal unit. However, such a zone-based approach not only has the unrealistic assumption that all attributes of a zone are uniformly spatially distributed throughout the zone, but also has resulted in serious methodological difficulties such as the modifiable areal unit problem and the incompatibility problem with environmental data. An alternative to the zone-based approach can be a pixel-based approach which gets its spatial dimension through a pixel. This paper proposes a pixel-based approach to linking remotely sensed data with socioeconomic data in GIS for urban quality of life assessment. The pixel-based approach uses dasymetric mapping and spatial interpolation to spatially disaggregate socioeconomic data and integrates remotely sensed data with spatially disaggregated socioeconomic data for the quality of life assessment. This approach was implemented and compared with a zone-based approach using a case study of Fulton County, Georgia. Results indicate that the pixel-based approach allows for the calculation of a microscale indicator in the urban quality of life assessment and facilitates efficient data integration and visualization in the assessment although it costs an intermediate step with more processing time such as the disaggregation of zonal data. The results also demonstrate that the pixel-based approach opens up the potential for the development of new database and increased analytical capabilities in urban analysis.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.4
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• pp.43-54
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• 2007

This paper presents design and verification of a face detection hardware for real time application. Face detection algorithm detects rough face position based on already acquired feature parameter data. The hardware is composed of five main modules: Integral Image Calculator, Feature Coordinate Calculator, Feature Difference Calculator, Cascade Calculator, and Window Detection. It also includes on-chip Integral Image memory and Feature Parameter memory. The face detection hardware was verified by using S3C2440A CPU of Samsung Electronics, Virtex4LX100 FPGA of Xilinx, and a CCD Camera module. Our design uses 3,251 LUTs of Xilinx FPGA and takes about 1.96${\sim}$0.13 sec for face detection depending on sliding-window step size, when synthesized for Virtex4LX100 FPGA. When synthesized on Magnachip 0.25um ASIC library, it uses about 410,000 gates (Combinational area about 345,000 gates, Noncombinational area about 65,000 gates) and takes less than 0.5 sec for face realtime detection. This size and performance shows that it is adequate to use for embedded system applications. It has been fabricated as a real chip as a part of XF1201 chip and proven to work.

• Korean Journal of Remote Sensing
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• v.31 no.2
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• pp.101-110
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• 2015

Synthetic Aperture Radar Interferometry (InSAR) is affected by various noise source such as atmospheric artifact, orbital error, processing noise etc.. Especially, one of the dominant noise source for long-wave SAR system, such as ALOS PALSAR (L-band SAR satellite) is the ionosphere effect because phase delays on radar pulse through the ionosphere are proportional to the radar wavelength. To avoid misinterpret of phase signal in the interferogram, it is necessary to detect and correct ionospheric errors. Recently, a MAI (Multipler Aperture SAR Interferometry) based ionospheric correction method has been proposed and considered one of the effective method to reduce phase errors by ionospheric effect. In this paper, we introduce the MAI-based method for ionospheric correction. Moreover we propose an efficient method that apply the method over non-coherent area using directional filter. Finally, we apply the proposed method to the ALOS PALSAR pairs, which include the west sea coast region in Korea. A polynomial fitting method, which is frequently adopted in InSAR processing, has been applied for the mitigation of phase distortion by the orbital error. However, the interferogram still has low frequency of Sin pattern along the azimuth direction. In contrast, after we applied the proposed method for ionospheric correction, the low frequency pattern is mitigated and the profile results has stable phase variation values within ${\pm}1rad$. Our results show that this method provides a promising way to correct orbital and ionospheric artifact and would be important technique to improve the accuracy and the availability for L-band or P-band systems.

• Radiation Oncology Journal
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• v.20 no.4
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• pp.391-395
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• 2002

Purpose : To confirm the accuracy of the radiation dose at the isocenter by the standard linear accelerator-based stereotactic radiosurgery technique which was developed at Seoul National University Hospital. Materials and Methods : Radiation dosimetry was undertaken during standard 5-arc radiosurgery using 6 MV X-ray beam from CL2100C linac. The treatment head was attached with circular tertiary collimators of 10 and 20 mm diameter. We measured the absorbed dose at the isocenter of a multi-purpose phantom using two kinds of detector : a 0.125 co ionization chamber and a silicon diode detector. Results : The dose differences at each arc plane between the planned dose and the measured dose at the isocenter raged from $-0.73\%\;to\;-2.69\%$ with the 0.125 cc ion chamber, and from $-1.29\%\;to\;-2.91\%$ with the diode detector during radiosurgery with the tertiary collimator of 20 mm diameter. Those with the 10-mm tertiary collimator ranged from $-2.39\%\;to\;-4.25\%$ with the diode. Conclusion : The dose accuracy at the isocenter was ${\pm}3\%$. Therefore, further efforts such ws modification in processing of the archived image through DICOM3.0 format are required to lessen the dose difference.

• Korean Journal of Microbiology
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• v.37 no.2
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• pp.130-136
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• 2001

The killing effects of two types(one-phase reactor and two-phase reactor) of UV-TiO$_2$photocatalytic system on the microorganisms have been studied. The UV-lamp which emits maximum 39 watts at 254 nm was prepared in these system. Three types of $TiO_2$ coating method were adopted. One type is thin film coated form on the quartz tube in the reactor and another one is surface rough coated form on the glass bead. The other one is $TiO_2$-mixed alginate bead form. UV irradiation was carried out for 1 min. In case of one phase reactor, the bactericidal efficiencies of E. coli by $TiO_2$-coated quartz tube and $TiO_2$-coated glass bead were 63.2% and 89.9%, respectively. In the air-bubbling system, the bactericidal efficiency was 95%, however, the efficiency decreased to 90.6% in the non-bubbling system. In the $TiO_2$-mixed alginate bead system, bactericidal efficiency was 86%. When $H_2O$$_2$ was treated (10, 15, 20, and 25 mg/ι) to the $TiO_2$-coated glass bead reactor, bactericidal efficiency significantly increased according to the concentration of $H_2$$O_2$. Two phase reactor showed more elevated efficiency. E. coli was more sensitive to the reaction than S. cerevisiae.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.8
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• pp.56-63
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• 2010

This work proposes a 12b 100MS/s 0.13um CMOS pipeline ADC for battery-powered mobile video applications such as DVB-Handheld (DVB-H), DVB-Terrestrial (DVB-T), Satellite DMB (SDMB), and Terrestrial DMB (TDMB) requiring high resolution, low power, and small size at high speed. The proposed ADC employs a three-step pipeline architecture to optimize power consumption and chip area at the target resolution and sampling rate. A single shared and switched op-amp for two MDACs removes a memory effect and a switching time delay, resulting in a fast signal settling. A two-step reference selection scheme for the last-stage 6b FLASH ADC reduces power consumption and chip area by 50%. The prototype ADC in a 0.13um 1P7M CMOS technology demonstrates a measured DNL and INL within 0.40LSB and 1.79LSB, respectively. The ADC shows a maximum SNDR of 60.0dB and a maximum SFDR of 72.4dB at 100MS/s, respectively. The ADC with an active die area of 0.92 $mm^2$ consumes 24mW at 1.0V and 100MS/s. The FOM, power/($f_s{\times}2^{ENOB}$), of 0.29pJ/conv. is the lowest of ever reported 12b 100MS/s ADCs.

• Korean Journal of Optics and Photonics
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• v.29 no.1
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• pp.19-27
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• 2018

A change in object distance would generally change the magnification of an optical system. In this paper, we have proposed and designed a double-Gauss optical system with a fixed magnification and image surface regardless of any change in object distance, according to moving the lens groups a little bit to the front and rear of the stop, independently parallel to the direction of the optical axis. By maintaining a constant size of image formation in spite of various object-distance changes in a projection system such as a head-up display (HUD) or head-mounted display (HMD), we can prevent the field of view from changing while focusing in an HUD or HMD. Also, to check precisely the state of the wiring that connects semiconductor chips and IC circuit boards, we can keep the magnification of the optical system constant, even when the object distance changes due to vertical movement along the optical axis of a testing device. Additionally, if we use this double-Gauss optical system as a vision system in the testing process of lots of electronic boards in a manufacturing system, since we can systematically eliminate additional image processing for visual enhancement of image quality, we can dramatically reduce the testing time for a fast test process. Also, the Gaussian bracket method was used to find the moving distance of each group, to achieve the desired specifications and fix magnification and image surface simultaneously. After the initial design, the optimization of the optical system was performed using the Synopsys optical design software.