• Proceedings of the Korea Information Processing Society Conference
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• 2002.04a
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• pp.139-142
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• 2002

본 논문은 이 기종간의 표준 압축형식을 변환하는데 있어 실시간 변환이 가능하도록 하며 프레임의 특성을 이용하여 압축률을 좀 더 높여 보는데 그 목적을 두고 있다. 이 기종간의 표준 압축형식 변환으로 MPEG2에서 H.263으로의 변환을 시도하였다. MPEG2에서 H.263으로 변환 시 압축률을 높이기 위한 분석결과 MPEG2 의 P 프레임내 인트라 매크로블록이 H.263 의 P 프레임의 인트라 매크로블록 수보다 많다는 것을 알 수 있었다. 따라서 본 논문에서는 P 프레임의 압축률을 높이기 위하여 P 프레임내의 인트라 매크로블륵 변환 과정에 움직임 예측과정을 삽입하고 움직임 예측 과정의 복잡도를 줄이기 위하여 Guided 탐색 방법을 사용하여 MPEG2 P 프레임에 생성된 인트라 매크로블록의 개수를 줄일 수 있다는 것을 제안하였다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2022.06a
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• pp.54-57
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• 2022

본 논문에서는 심층 신경망 기반 점진적 다계층 오디오 코덱의 비트 전송률 효율 향상을 위한 엔트로피 모델 기반 양자화 방식을 제안한다. 최근 심층 신경망을 이용하여 전통적인 신호 처리 이론 기반의 상용 오디오 코덱들을 대체하기 위한 오디오 압축 및 복원 시스템에 관한 연구가 활발하게 이루어지고 있다. 그러나 아직은 기존 상용 코덱의 성능에 도달하지 못하고 있으며 특히 종단 간 오디오 압축 모델의 경우, 적은 정보량으로 높은 품질을 얻기 위해서는 부호화기의 양자화 구조를 개선하는 것이 필수적이다. 본 연구에서는 기존에 제안된 종단 간 오디오 압축 모델 중 하나인 점진적 다계층 오디오 코덱의 벡터 양자화기를 엔트로피 모델 기반 양자화기로 대체하고 전송률-왜곡 트레이드오프 관계를 활용하여 전송률을 다양한 형태로 조절할 수 있음을 보임으로써 엔트로피 모델 기반 양자화기 도입의 타당성을 검증한다.

• Progress in Medical Physics
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• v.22 no.1
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• pp.52-58
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• 2011

Our goal is to assess the suitability of a glass dosimeter on detection of high-energy electron beams for clinical use, especially for radiation therapy. We examined the dosimetric characteristics of glass dosimeters including dose linearity, reproducibility, angular dependence, dose rate dependence, and energy dependence of 5 different electron energy qualities. The GD was irradiated with high-energy electron beams from the medical linear accelerator andgamma rays from a cobalt-60 teletherapy unit. All irradiations were performed in a water phantom. The result of the dose linearity for high-energy electron beams showed well fitted regression line with the coefficient of determination; $R^2$ of 0.999 between 6 and 20 MeV. The reproducibility of GDs exposed to the nominal electron energies 6, 9, 12, 16, and 20 MeV was ${\pm}1.2%$. In terms of the angular dependence to electron beams,GD response differences to the electron beam were within 1.5% for angles ranging from $0^{\circ}$ to $90^{\circ}$ and GD's maximum response differencewas 14% lower at 180o. In the dose rate dependence, measured dose values were normalized to the value obtained from 500 MU/min. The uncertainties of dose rate were measured within ${\pm}1.5%$ except for the value from 100 MU/min. In the evaluation of the energy dependence of the GD at nominal electron energies between 6 and 20 MeV, we obtained lower responses between 1.1% and 4.5% based on cobalt-60 beam. Our results show that GDs have a considerable potentiality for measuring doses delivered by high-energy electron beams.

• Journal of Korean Ophthalmic Optics Society
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• v.5 no.1
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• pp.7-11
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• 2000

The anti-reflective anti-static (ARAS) optical film is designed using absorbent materials such as ITO, $TiN_xW_y$, Ag by Essential Macleod program. [air ${\mid}TiN_xW_y{\mid}SiO_2{\mid}$ glass] two layer shows wide-band AR coating in the wavelength range of 450~700 nm. The reflectivity, transmittance of this coating are below 0.5%, about 75%, respectively. [air $SiO_2{\mid}TiO_2{\mid}SiO_2{\mid}$, ITO glass] layer can adjust reflectance of below 0.5% with above 97% transmittance. In the [air ${\mid}SiO_2{\mid}TiO_2{\mid}SiO_2{\mid}$ Ag glass] layer, the transmission can be controlled at above 96% with reflectance of 1~2%.

• Proceedings of the Korea Society for Industrial Systems Conference
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• 1998.03a
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• pp.89-92
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• 1998

압연철판의 생산라인에 있는 카메라에 입력되는 영상정보를 Image Frame Grabber를 이용하지 않고 Video Overlay Board를 사용하여 라인에 입력되는 압연철판을 분석하여 외곽선을 가로지른 선분의 길이가 기준에 준할 때 정확한 절단정보를 발생시킴으로 기존에 사용해온 작업자의 대략적인 지식을 이용한 절단에서 발생되는 압연 철판의 손실을 최소화시키며 불량률을 줄인다. 그리고 발생되는 정보를 DB화시킴으로 생산품의 정확한 재고량을 관리하는 시스템을 개발한다.

• Information and Communications Magazine
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• v.32 no.12
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• pp.38-44
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• 2015

국내 철도 지선 구간에서는 열차 운행 빈도와 승객 이용률이 저조하여, 기존 열차제어시스템의 유지보수 비용을 최소화하고 운영 효율성을 향상시킬 필요성이 대두되었다. 이에 따라 고가의 지상신호 제어장치 대신 차상에서 선로변 시설물을 무선으로 제어하고자 하는 차상중심 열차제어시스템이 개발 중이다. 본고에서는 차상중심 열차제어시스템의 개념과 운영을 위한 고려 사항 및 현재 개발 동향을 살펴본다.

• Journal of the Institute of Convergence Signal Processing
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• v.17 no.1
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• pp.32-39
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• 2016

Intelligent Transport Systems (Intelligent Transportation System: ITS) is a system for inducing a flow of ideal car for using the most advanced technology, it is determined the status of the road, and take appropriate action. In order to be measured at various time points, and is managed, the information about the traffic situation is used image using a computer mainly. The image processing using a computer, it is an easy way to collect parameters of the various traffic in real time, technology has developed more and more. Vehicle detection of transport parameters of intelligent transportation system is a very important technology basically. Therefore, technology detection method using car background images and the contour line extraction method using an edge is used, however, problems have been raised on the accuracy of the detection rate.

• Radiation Oncology Journal
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• v.16 no.3
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• pp.337-345
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• 1998

Purpose : To obtain the uniform dose at limited depth to entire surface of the body, the dose characteristics of degraded electron beam of the large target-skin distance and the dose distribution of the six-dual electron fields were investigated Materials and Method : The experimental dose distributions included the depth dose curve, spatial dose and attenuated electron beam were determined with 300 cm of target-skin distance (TSD) and full collimator size (35*35 $cm^2$ on TSD 100 cm) in 4 MeV electron beam energy. Actual collimated field size of 105 cm * 105 cm at the distance of 300 cm could include entire hemibody. A patient was standing on step board with hands up and holding the pole to stabilize his/her positions for the six-dual fields technique. As a scatter-degrader, 0.5 cm of acrylic plate was inserted at 20 cm from the body surface on the electron beam path to induce ray scattering and to increase the skin dose. Results : The full width at half maximum(FWHM) of dose profile was 130 cm in large field of 105*105 $cm^2$ The width of $100\pm10\%$ of the resultant dose from two adjacent fields which were separated at 25 cm from field edge for obtaining the dose unifomity was extended to 186 cm. The depth of maximum dose lies at 5 mm and the 80$\%$ depth dose lies between 7 and 8 mm for the degraded electron beam by using the 0.5 cm thickness of acrylic absorber. Total skin electron beam irradiation (TSEBI) was carried out using the six dual fields has been developed at Stanford University. The dose distribution in TSEBI showed relatively uniform around the flat region of skin except the protruding and deeply curvatured portion of the body, which showed excess of dose at the former and less dose at the latter. Conclusion : The percent depth dose, profile curves and superimposed dose distribution were investigated using the degraded electron beam through the beam absorber. The dose distribution obtained by experiments of TSEBI showed within$\pm10\%$ difference except the protruding area of skin which needs a shield and deeply curvatured region of skin which needs boosting dose.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.3
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• pp.843-854
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• 2013

This paper presents experimental research work for the evaluation of ultimate flexural behaviors of prestressed concrete beams with a corroded tendon. In order to evaluate the effects of loss of prestress or loss of tendon area on the ultimate flexural strength of prestressed concrete beams, static load tests are conducted using five prestressed concrete beams. After exposing prestressing tendons in two test beams using 25mm drill bit, the exposed tendons were corroded using an accelerating corrosion equipment to simulate loss of tendon area. During the tests, steel strains, concrete strains and displacements at the center of test beams were measured, and acoustic emission measurements were conducted to detect wire fractures. Based on the test results, evaluation method for predicting flexural strength of prestressed concrete beams with corroded tendons is investigated. In addition, evaluation methods for predicting the existence of corroded tendons in post-tensioned prestressed concrete beams at service loads are discussed.

• Journal of Sensor Science and Technology
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• v.9 no.4
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• pp.274-280
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• 2000

This paper deals with an experimental study to apply commercial semiconductors to measure radiation dose rate for gamma ray. Since the low cost, small size, high efficiency and ruggedness of silicon photodiodes make them attractive photodetectors, they coulde be effectively used in measuring any radiation such as gamma ray. Most PN photodiodes show that the reverse current increases when the light is increased. Therefore the depletion region of them have influence on the reverse current, so we choose silicon PIN photodiodes with large depletion region. In order to detect radiation dose rate and then, to apply in developing any gamma ray dosimeter, some examinations and experiments were performed to PIN photodiodes in this work. Two kinds of PIN photodiodes, such as NEC's PH302 and SIEMENS's BPW34, were tested in a Co-60 gamma irradiation facility with a semiconductor parameter analyzer. As a result, we found that such PIN photodiodes present good linearity in diode current characteristics with dose rate. Therefore silicon PIN photodiodes could be suitably used in designing gamma ray dosimeters.