• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 2002년도 Proceedings
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• pp.373-375
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• 2002

4D CT is a dynamic volume imaging system of moving organs with an image quality comparable to conventional CT, and is realized with continuous and high-speed cone-beam CT. In order to realize 4D CT, we have developed a novel 2D detector on the basis of the present CT technology, and mounted it on the gantry frame of the state-of-the-art CT-scanner. In the present report we describe the design of the first model of 4D CT-scanner as well as the early results of performance test. The x-ray detector for the 4D CT-scanner is a discrete pixel detector in which pixel data are measured by an independent detector element. The numbers of elements are 912 (channels) ${\times}$ 256 (segments) and the element size is approximately 1mm ${\times}$ 1mm. Data sampling rate is 900views(frames)/sec, and dynamic range of A/D converter is 16bits. The rotation speed of the gantry is l.0sec/rotation. Data transfer system between rotating and stationary parts in the gantry consists of laser diode and photodiode pairs, and achieves net transfer speed of 5Gbps. Volume data of 512${\times}$512${\times}$256 voxels are reconstructed with FDK algorithm by parallel use of 128 microprocessors. Normal volunteers and several phantoms were scanned with the scanner to demonstrate high image quality.

• Journal of Biosystems Engineering
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• 제26권5호
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• pp.423-430
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• 2001

The purpose of this study is to develop high-speed rotary tillage system for a power tiller by improving the rotary blade and the power train of transmission. Mechanical structure of gear train of rotary drive of conventional power tiller was simplified so that power can be transmitted directly from second shaft to tilling speed change shaft by rotating freely the transfer gear which changes the direction of rotation of shafts using needle bearing installed into middle shaft. A new gear train suitable for the single-edged rotary blade and high-speed rotary drive was developed with the rotational speed of rotary shaft faster than 7.5% at 1st-speed and 1.4% at 2nd-speed the one of conventional system by changing the numbers of teeth of gears of middle shaft, tilling speed change shaft and PTO shaft. Using the developed gear train for high-speed rotary drive, field tests were performed to compare tillage performances by the developed single-edged blade and by the conventional double-edged blade. The results showed that the performances by the single-edged blade compared with the one by the double-edged blade was improved about 18% in field capacity, about 34% in fuel consumption, and 9.4% in soil crushing ratio. Therefore, it may be concluded that tillage performance by the single-edged blade was improved compared to the one by the conventional blade. Evaluation of the developed system consisting of single-edged blade and gear train for high-speed rotary drive in field revealed that tillage performance of the developed system was similar to the one of field test conducted using the system consisting of single-edged blade and gear train for rotary drive of conventional power tiller However, considering the higher cone index of the upland field where evaluation was carried out compare to the one of the ordinary paddy field, it may be concluded that tillage performance of the developed rotary tilling system better than the one of conventional system.

• 한국식품과학회지
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• 제23권4호
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• pp.437-441
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• 1991

원심식 박막증발기를 이용해 마늘착즙을 증발 농축하면서 급액속도가 증발표면에서의 액의 흐름상태와 운전 특성에 미치는 영향에 대해서 조사하였다. 급액속도 $25{\sim}125kg/h$의 운전 조건하에서 증발표면에서의 이론적인 박막의 두께는 $0.52{\sim}0.89mm$ 그리고 체류시간은 $1.77{\sim}6.75$초로 계산되었다. 한편 Reynolds number로 판단해 볼 때 증발표면에서의 마늘착즙의 흐름은 대체로 층류로 여겨졌다. 일정한 증기 및 증발온도 조건하에서 농축비는 급액속도가 증가함에 따라 감소한 반면 증발속도와 총괄열전달계수는 어느 일정한 값까지 증가하다가 감소하는 경향을 나타내었다. 그리고 급액속도 $25{\sim}125kg/h$(증발온도 $40^{\circ}C$, 증기온도 $95{\sim}120^{\circ}C$, 급액의 초기농도 $32^{\circ}Brix$)에서 농축비는 $1.04{\sim}2.04$, 총괄열전달계수는 $3,074.33{\sim}17,614.70kJ/m^{2}{\cdot}h{\cdot}^{\circ}C$ 였다.

• 한국방사선학회논문지
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• 제7권3호
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• pp.175-179
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• 2013

파노라마와 CBCT 같은 회전하는 방사선 발생장치에서 방사선작업종사자와 보호자의 적절한 피폭 방어 대책을 알아보고자 위치에 따른 방사선 조사선량을 비교 분석하였다. 사용된 장치로는 파노라마 DP-90-P PAX-500(Vatech, Korea)와 CBCT DCT-90-P IMPLAGRAPHY Dental CT system (Vatech, Korea)을 사용하였다. 조사선량 측정기는 Ion chamber model 2026과 Reader기 20X5-60E를 사용하였다. 촬영조건은 임상에서 사용하는 인자와 동일하게 설정하였다. 실험결과 파노라마는 검사가 처음 시작하는 A지점이 81${\mu}R$ 으로 가장 높게 나왔고, 검사가 끝나는 D점이 53${\mu}R$ 으로 가장 낮게 나왔다. CBCT의 경우는 검사가 끝나는 D지점이 1,021${\mu}R$ 으로 가장 높게 나왔고, 검사가 시작하는 A지점이 809.67${\mu}R$ 으로 가장 높게 측정되었다. 부득이하게 보호자나 방사선작업종사자가 환자를 잡고 검사해야 할 경우에는 피폭선량이 가장 많은 지점을 피해서 X선관이 회전하기 시작하는 지점과 끝나는 지점의 가운데 위치해야 할 것이다. 그리고 장비의 특성상 기계의 반대편이며, 환자의 측면에서 지지하는 것보다 후방에서 지지하는 것이 가장 안전할 것이고, 적절한 방호기구를 착용해야 할 것이다.