• Radiation Oncology Journal
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• 제13권2호
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• pp.199-203
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• 1995

Purpose: To evaluate the dose under lung block as a function of depth and the effectiveness of a block as a function of block width. Materials and Methods : Field size of mantle field was $22.8{\times}32.4cm^2.$ Dose distribution of the mantle field was measured with two dimensional water phantom system. To analyze the effectiveness of the lung block. central axis plane, 5cm off-axis plane, and 10cm off-axis plane were studied. Results: The dose under the lung block was recorded with maximum at the depth between 5cm and 10cm. In the central axis plane, dosimetric block width was $10-15\%$ less than physical block width. In the 5cm off-axis plane, dosimetric block width was $4-9\%$ less than physical block width. In the 10cm off-axis plane, dosimetric block width was $2\%$ less than physical block width. Conclusion: Depth dependence of the dose under the lung block was founded. Also, block width dependence of the lung block was founded. To induce the accurate relation between the physical block width and the 'effective' block width, it needs more detailed understanding of the variables involved.

• 대한기계학회논문집B
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• 제32권10호
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• pp.776-783
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• 2008

The object of this paper is to study on the thermal performance of a micro channel water block for computer CPU cooling. The effects of liquid flow rate, micro channel width and height on the thermal performances of water block are investigated experimentally. The water block was fabricated Al and machined with a micro milling. The water block consisted of rectangular micro channels 0.5 to 0.9 mm width and 1.5 to 4.5 mm height. The experiments were conducted using deionized water, over a liquid flow rate ranging from 0.2 to 2.0 kg/min. The base temperature and thermal resistance decrease with increasing of liquid flow rate. The increase of a channel height is more effective on the thermal resistance than the decrease of a channel width. At the flow rate of 0.7 kg/min, input power of 100 W, the base temperature and thermal resistance of sample 6 is $33^{\circ}C$ and $0.13\;^{\circ}C/W$ respectively.

• 한국의학물리학회지:의학물리
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• 제5권2호
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• pp.45-48
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• 1994

방사선 치료분야에서 Conformal Therapy에 이용되는 Multileaf Collimator(MLC) leaf 폭 분포에 관한 연구를 하였다. 이미 방사선 치료를 받은 303명 환자의 1169 치료 조사면 차폐 블럭 사용빈도 유형을 조사하여 block 사용빈도가 잦은 곳은 leaf 폭을 좁게 배치하고, 사용빈도가 성긴 곳은 leaf 폭을 두껍게 배치하였다. 전체 leaf 폭 평균은 0.8 cm이되, 실제 차폐 블럭 사용빈도가 높은 부위(치료중심에서 3-6 cm)에서는 MLC leaf 폭이 0.5-0.6 cm의 치료 효과를 볼 수 있도록 불균일 leaf 폭 분포를 갖는 MLC를 고안하였다.

• 전자공학회논문지
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• 제52권2호
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• pp.119-124
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• 2015

본 논문은 광원 라인폭이 spectral amplitude coding (SAC) OCDMA 시스템에 미치는 영향을 구하였다. q와 m값에 따라 다양한 코드를 구현할 수 있으므로 symmetric balance incomplete block design(BIBD) 코드를 분석에 사용하였다. 그 결과 입력파워가 큰 경우 ($P_{sr}=-10dBm$) 이상적인 BIBD 코드가 비이상적인 BIBD 코드보다 더 좁은 광원 라인폭이 요구되었다. 그러나 입력파워가 작은 경우 ($P_{sr}=-25dBm$)에는 그 반대로 비이상적인 BIBD 코드가 이상적인 BIBD 코드보다 더 좁은 광원 라인폭이 필요했다.

• 구강회복응용과학지
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• 제22권2호
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• pp.161-171
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• 2006

Endosseous implants have restored normal function and dental health to many patients. When implants were introduced as an effective treatment modality, their efficacy was limited by the amount of available bone. Today, various grafting procedures can surgically create bone width and volume. Implants can be placed in more ideal locations for successful prosthetic reconstruction. The use of autogenous bone grafts represents the "gold standard" for bone augmentation procedures. Either intraoral or extraoral sites may be considered for donor sites. Alveolar ridge augmentation using autogenous bone block, can be done during implant placement or staged with implant placement, after bone graft healing. In the staged technique, a better implant positioning and the use of wide diameter implants are possible. Alveolar ridge augmentation using autogenous block graft is a predictable way of treatment, for the atrophic alveolar ridge before implant placement. The cases presented in this article clinically demonstrate the efficacy of using a autogenous block graft in generating effective new bone fill for dental implant placement.

• Advances in concrete construction
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• 제5권5호
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• pp.451-468
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• 2017

The problem of reducing the self-weight of reinforced concrete structures is very important issue. There are two approaches which may be used to reduced member weight. The first is tackled through reducing the cross sectional area by using voids and the second through using light weight materials. Reducing the weight of slabs is very important as it constitutes the effective portion of dead loads in the structural building. Eleven slab specimens was casted in this research. The slabs are made one way though using two simple supports. The tested specimens comprised three reference solid slabs and eight styropor block slabs having (23% and 29%) reduction in weight. The voids in slabs were made using styropor at the ineffective concrete zones in resisting the tensile stresses. All slab specimens have the dimensions ($1100{\times}600{\times}120mm$) except one solid specimens has depth 85 mm (to give reduction in weight of 29% which is equal to the styropor block slab reduction). Two loading positions or cases (A and B) (as two-line monotonic loads) with shear span to effective depth ratio of (a/d=3, 2) respectively, were used to trace the structural behavior of styropor block slab. The best results are obtained for styropor block slab strengthened by minimum shear reinforcement with weight reduction of (29%). The increase in the strength capacity was (8.6% and 5.7%) compared to the solid slabs under loading cases A and B respectively. Despite the appearance of cracks in styropor block slab with loads lesser than those in the solid slab, the development and width of cracks in styropor block slab is significantly restricted as a result of presence a mesh of reinforcement in upper concrete portion.

• Radiation Oncology Journal
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• 제13권4호
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• pp.391-396
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• 1995

목적 : 컴퓨터의 발달에 힘입어 3-D Conformal Radiotherapy(3-D CRT)가 가능하게 되었고 3-D CRT를 위해서는 다엽콜리메이터(MLC)가 필수적인 장치이다. 이에 본 저자들은 MLC 사용시 반그림자(Penumbra)의 크기와 그 특성을 알아보고 기존의 합금납(lead alloy block)을 사용할 때의 반그림자와 차이를 비교 분석하여 임상에서 다엽콜리메이터(MLC)의 이용에 도움이 되고자 본 연구를 계획하였다. 방법 : MLC와 합금납의 반그림자를 측정하기 위해 6MV 와 10MV 에너지의 방사선을 이용하여 필름선량분석을 시행하였다. 필름에 각에너지의 dmax와 10cm 두께의 폴리스탈린 판톰을 올려 놓고 측정하였고, MLC의 종단면과 조사면의 y축과 이루는 각도를 변화시키면서 Effective penumbra($20{\%}-80{\%}$)와 $10{\%}-90{\%}$ 반그림자를 측정하였다. 결과 : MLC의 각도가 0o에서 75o로 증가함에 따라 반그림자의 크기가 증가 하였고, 반그림자 영역에서 등선량곡선의 부채살모양이 심화 되었다. dmax에서 보다 10cm 깊이에서 반그림자의 크기가 약간 증가하였고, 에너지가 증가 하면서 약간 반그림자가 커지는 경향성만 보였다. 합금납을 사용할 경우의 반그림자보다 MLC를 사용할경우 최대 4.8mm가 더 크게 측정되었다. 결론 : 3-D CRT를 시행함에 있어서 반그림자 영역에서는 기존의 합금납 차폐물을 대신하여 MLC를 사용하여도 무방하리라는 결론을 얻을 수 있었다.

• 한국주거학회논문집
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• 제25권1호
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• pp.23-32
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• 2014

This research progressed space evaluation test with 3D simulation for exterior space of detached housing area among the Seoul spaces of child sex offense in 2010. Based on changing analysis on natural surveillance by spatial changes of each physical element, the purpose is to suggest effective construction planning measure for preventing child sex offense. The results of research are as follows. First, natural surveillance of space's height differences and width differences were compared and analyzed. As the result, footpath shows that stairs of slope didn't make lots of effects on visual block, not block of spatial moving, because of the difference of stair height. Also, in case of parking space, visual connection with footpath is expanded when designing pilotis rather than heightening floor height, so activities of exterior people could be seen more easily. Therefore, natural surveillance was higher. Second, natural surveillance of architectural elements by changes of footpath' width was compared and analyzed. As the result, openness of footpath should be secured rather than openness of architectural element. And, planning autonomy of architectural form could be more expanded when securing openness of footpath.

• Computers and Concrete
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• 제32권4호
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• pp.351-363
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• 2023

Reducing the self-weight of reinforced concrete structures problem is discussed in this paper by using two types of self-weight reduction, the first is by using lightweight coarse aggregate (crushed brick) and the second is by using styropor block. Experimental and Numerical studies are conducted on (LWAC) lightweight aggregate reinforced concrete slabs, having styropor blocks with various sizes of blocks and the ratio of shear span to the effective depth (a/d). The experimental part included testing eleven lightweight concrete one-way simply supported slabs, comprising three as reference slabs (solid slabs) and eight as styropor block slabs (SBS) with a total reduction in cross-sectional area of (43.3% and 49.7%) were considered. The holes were formed by placing styropor at the ineffective concrete zones in resisting the tensile stresses. The length, width, and thickness of specimen dimensions were 1.1 m, 0.6 m, and 0.12 m respectively, except one specimen had a depth of 85 mm (which has a cross-sectional area equal to styropor block slab with a weight reduction of 49.7%). Two shear spans to effective depth ratios (a/d) of (3.125) for load case (A) and (a/d) of (2) for load case (B), (two-line monotonic loads) are considered. The test results showed under loading cases A and B (using minimum shear reinforcement and the reduction in cross-sectional area of styropor block slab by 29.1%) caused an increase in strength capacity by 60.4% and 54.6 % compared to the lightweight reference slab. Also, the best percentage of reduction in cross-sectional area is found to be 49.7%. Numerically, the computer program named (ANSYS) was used to study the behavior of these reinforced concrete slabs by using the finite element method. The results show acceptable agreement with the experimental test results. The average difference between experimental and numerical results is found to be (11.06%) in ultimate strength and (5.33%) in ultimate deflection.

• 대한전자공학회논문지
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• 제26권2호
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• pp.147-154
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• 1989

Custom VLSI 칩의 설계에 있어서 임의의 폭과 높이를 갖는 직사각형 마크로 블럭을 효과적으로 배치하는 것은 칩의 면적과 신호 지연시간을 줄이기 위하여 매우 중요하다. 이 논문에서는 시뮬레이티드 어닐링을 사용하여 마크로 블럭을 전체적으로 최적 배치하기 위한 방법과, 시뮬레이티드 어닐링 과정이 끝난 후에 남아있는 직사각형 블럭들 사이의 중첩을 제거하는 효율적인 알고리듬을 제안하였다. 최소한의 배선영역을 확보하기 위해 각 블럭을 4방향으로 확장한 후에, 확장된 블럭들을 최대한 밀집되도록 배치하였다. 이 방법을 MV10000/UNIX 컴퓨터에서 C언어로 프로그램 하였으며 50개와 160개의 블럭으로 구성된 회로에 적용한 결과 좋은 배치를 얻을 수 있었다. 또한 최종 배치에 큰영향을 주는 파라미터에 대한 조사를 하였다.