• 한국의학물리학회지:의학물리
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• 제10권2호
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• pp.83-88
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• 1999

목적 : 금속박막과 고체 팬텀이 선량 분포와 선량 측정에 미치는 영향을 연구하기 위하여 TLD 실험을 행하였다. 본 연구의 목적은 주어진 고체 팬텀 환경 내에서 TLD 기판 위에 놓인 금속박막의 build-up 효과와 깊이선량 분포를 알아보고자 하였다. 대상 및 방법 : 측정은 TLD 기판과 같은 면적 (3.2 $\times$ 3.2 $\textrm{mm}^2$)의 금속박막을 LiF TLD-100 위에 얹어서 행하였다. 여러 종류 (주석, 구리, 금) 의 다양한 두께 (0.1, 0.15, 0.2, 0.3 mm)를 가진 금속박막 중에 한 개를 TLD 기판 위에는 얹어서 각 각의 흡수선량을 측정하였다. 금속박막을 얹은 TLD 기판을 사용하여 고체 팬텀에서의 표면홉수선량과 최대 build-up 영역에서 흡수선량을 측정하였다. 결과 : 금속박막을 이용한 TLD 기판의 경우 표면흡수선량이 증가하였고, 물에 대한 금속의 등가 두께에 따른 표면흡수선량 곡선에는 build-up 이 뚜렷이 관측되었다. 최대 build-up 영역에서 관측한 흡수선량 측정값은 금속박막을 없지 않은 TLD의 경우보다 약 8% 에서 13% 정도의 보다 작은 값을 나타내었다. 결론 : TLD 선량 측정 시 금속 박막 법은 깊이에 따른 흡수선량 뿐 만 아니라 피부 표면으로부터 약 4.2mm 깊이까지의 홉수선량의 build-up 에 관련 정보를 의료진에 제공할 수 있으며, 금속박막을 얹은 TLD에 관한 실험 결과는 피부 특정 영역에서의 bolus 의 결정에 도움이 될 것으로 사료됨.

• 한국정밀공학회지
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• 제6권2호
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• pp.40-46
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• 1989

Recently, the researches on cutting the new material have been done for development of aerospace industrial engineering. Especially, titanium ally is well known as heat resisting, antiwear, anticorrosion and difficult-to-machine materials. Many studies on the analysis of shear angle have been done for improving productivity in cutting these materials. In case of titanium alloy, the saw-toothed type of chip which has wave surface of a triangular form, an eccentric from of a continuous type of chip that is produced in the cutting process, was checked. Nakayama supposed that a maximum shear strewss plane and the shear crack in the free surface made an angle of $45^{\circ}$ .deg. , but it's usually much larger than that. In this paper, the author analyzed the shear conditions of the cutting process in the quick-stopping device with the help SEM-photographs, and measured the hypotenuse angle directly in the photographs of the chips. In conclusion, the author tried to find the shear angle in the cutting process with the saw-toothed chip and compared it with the shear angles which can be calculated from the theories established by others. The results obtained are as follows. 1. In case of the saw-toothed chips, the equivalent cutting ratio can be calculated by using the chip thickness to two-thirds of ramp height. 2. The theory of Ernst-Merchant is not applicable to the titanium and its alloys which does not fractured in accordance with the theory of maximum shear stress. 3. When we cut the titanium alloys which produced the saw-toothed chips, the shear angle can be found with the theories of Rowe-Spick, P.K. Wright and the measurement of hypotenuse angle.

• 한국ITS학회 논문지
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• 제2권2호
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• pp.65-72
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• 2003

본 연구를 통하여 MMC(Microwave Micro Cell)를 위한 무선 중계 시스템과 ITS용 무선장비등에 사용 될 수있는 6단의 하이브리드 전력증폭기를 설계 및 제작하였다. 전력 증폭기 각단의 능동소자는 bare chip 형태의 Hetero-junction Power FET를 이용하였으며, $\varepsilon_{r}$=9.9, 15-mil 두께의 알루미나기판을 사용하여 제작하였다. 측정 결과 시스템의 순방향 주파수인 17.6GHz - 17.gGEU에서 33.2~36.5dB의 소신호 이득과 33.0$\~$34.0dBm까지의 출력전력을 얻었고, 역방향 주파수인 19.0GHt$\~$19.2GHz에서 36.0$\~$37.0dB의 소신호 이득을 출력전력은 33.0$\~$34.5dBm을 얻었다.

• 한국전자파학회논문지
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• 제24권6호
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• pp.595-601
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• 2013

본 논문에서는 CMOS 공정을 사용한 밀리미터파 대역 온-칩 다이폴 안테나의 최적화된 설계를 제안한다. CMOS 공정을 사용한 안테나에서 가장 큰 단점은 기판의 높은 유전율과 손실로 인하여 공기 중 방사 효율이 낮다는 것이다. 이를 극복하기 위한 방법으로 공기 중의 방사 영역 증가와 안테나와 반사체의 거리 최적화가 필요하다. 80 GHz에서 16.5 %의 효율과 22.3 %의 대역폭을 가지는 다이폴 안테나의 최종 설계에서 공기 중 방사 영역을 넓히기 위한 방법으로 기판 각도, 칩 가장자리-다이폴 사이 거리를 변화시켰으며, 안테나와 반사체 사이의 거리를 최적화하기 위한 방법으로 기판 두께와 안테나-접지면 사이 거리를 조절하며, 설계 환경이 안테나의 효율에 미치는 영향을 체계적으로 분석하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 춘계학술대회 논문집
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• pp.907-911
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• 2000

In this study, a modified model for prediction of cutting force components in down end milling process is presented. Using this cutting force components of 4-tooth endmills with various helix angles have been predicted. Predicted values of cutting force components are well coincide with the measured ones. As helix angle increases overlapping effects of the active cutting edges increase and as a result the amplitudes of cutting force components decrease.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2000년도 춘계학술대회논문집 - 한국공작기계학회
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• pp.3-7
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• 2000

In this study, a modified model for prediction of cutting force components in up end milling process is presented. Using this cutting force components of 4-tooth endmils with various helix angles have been predicted. Predicted value of cutting force components are well coincide with the measured ones. As helix angle increases overlapping effects of the active cutting edges increase and as a result the amplitudes of cutting force components decrease and the specific cutting energy consumed also decreases

• 한국생산제조학회지
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• 제5권3호
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• pp.58-65
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• 1996

This thesis is concerned with the study on the characteristics of the cutting resistance occurring in finish machining of hardened steels such as carbon tool steel and alloy tool steel by a ceramic tool with nose radius. For the purpose, the shape of cutting cross-section made at nose part of the tool was analyzed geometrically and the wear mechanism on the flank face of the ceramic tool is investigated. In order to investigate the characteristics of cutting resistance two categories of cutting conditions are suggested, along with geometrical analysis. One category includes the conventional cutting parameters such as feed and depth of cut, another containing new cutting parameters of thickness of cut and width of cut etc. Thickness of cut width of cut and area of undeformed chip section formed by the condition of engagement between workpiece and cutting tool are determined as the function of feed, depth of cut and nose radius of cutting too, And an effective approach angle is determined by depth of cut and nose radius.

• 한국가구학회지
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• 제11권2호
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• pp.67-72
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• 2000

Some physical characteristics as thickness swelling, heat conduction, and bending properties of composite hoards made of waste wood chip and charcoal were measured. Wood-charcoal composite boards of three types and cement board were prepared for this study as shown in Table 1, Keeping duration of strawberries in the boxes($25cm{\times}25cm{\times}25cm$) manufactured with the boards was also examined. Thickness swelling and bending properties(MOR and MOE) of board B and C were lower than those of board A. Among the wood-charcoal composite boards except cement board, there were no differences in heat conduction(mm/sec.). Strawberries in the box with board C were kept longer duration in fresh condition than that with cement board. From the results, it is suggested that wood-charcoal composite boards can be used for eco-material.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제55권4호
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• pp.199-203
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• 2006

This paper presents an ASER (Accelerated Soft Error Rate) integral model. The model is based on the facts that the generated EHP/s(electron hole pairs) are diminished after some residual range of the incident alpha particle, where residual range is a function of the incident angle and the capping layer thickness over the semiconductor junction. The ASER is influenced by the flux of the alpha particles, the junction area ratio, the alpha particle incident angle when the critical charge is same as the collected charge, and the sizes of the alpha source and the chip. The model was examined with 8M static RAM samples. The measured ASER data showed good agreement with the calculated values using the model. The ASER decreased exponentially with respect to the operational voltage. As the capping layer thickness increases up to $16{\mu}m$, the ASER increases, and after that thickness, the ASER decreases. The ASER increased as the depth of BNW increased from $0{\mu}m\;to\;4{\mu}m$. and then saturated. The ASER decreased as the node capacitance increased from 2fF to 5fF.

• Design & Manufacturing
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• 제14권4호
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• pp.58-64
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• 2020

Lately, the development of the semiconductor industry has led to the miniaturization of electronic devices. Therefore, semiconductor wafers of very thin thickness that can be used in Multi-Chip Packages are required. There is active research on the backgrinding process to reduce the thickness of the wafer. The backgrinding process polishes the backside of the wafer, reducing the thickness of the wafer to tens of ㎛. The equipment that performs the backgrinding process requires ultra-precision. Currently, there is no full auto backgrinding equipment in Korea. Therefore, in this study, ultra-precision backgrinding equipment was designed. In addition, finite element analysis was conducted to verify the equipment design validity. The deflection and structural stability of the backgrinding equipment were analyzed using finite element analysis.