• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 1993년도 추계학술대회 논문집
• /
• pp.83-88
• /
• 1993

Recently, the analysis of microcutting with submicrometer depth of cut is tried to get a more high quality surface product, but to get a valuable result another method instead of conventional finite element method must be considered because finite elment method is impossible for a very small focused region and mesh size. As the altermative method, Molecular Dynamics or Statics is suggested and acceoted in the field of microcutting, indentation and crack propagation. In this paper using Molecuar Dynamics simulation, the phenomena of microcutting with subnanometer chip thickness is studied and the cutting mechanism for tool edge configuration is evaluated. As the result of simulation the atomistic chip formation is achieved.

• 전자공학회논문지A
• /
• 제28A권11호
• /
• pp.880-886
• /
• 1991

Multi-layered chip inductors were prepared with good magnetic properties by sintering Ni-Zn-Cu ferrites at a lower temperature. A slurry with 49.5mol%Fe$_{2}O_{3}$, 20.5mol% ZnO, 20mol% NiO and 10nol% CuO was cast into tapes with 60-100\ulcorner of thickness with a doctor blade techniques. The tapes were screen-pronted with 100% silver electrodes, layered and pressed at 250kg/cm$^{2}$ and then sintered ant 900$^{\circ}C$ for 2h. Inductance with internal electrodes printed 5, 10, and 15 turns showed 4.9, 15 and 24$\mu$, respectively, at 1MHz.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2001년도 춘계학술대회 논문집
• /
• pp.1042-1047
• /
• 2001

A mechanistic model is developed to predict the thrust force and cutting torque of drilling process including wear. A mechanistic oblique cutting force model is used to develop the drilling force model. The cutting lips are divided into small elements and elemental forces are calculated by multiplying the specific cutting pressure with the elemental chip area. The specific cutting pressure is a function of chip thickness, cutting velocity, rake angle and wear. The total forces are then computed by summing the elemental forces. Measured cutting forces are in good agreement with the simulated cutting forces.

• 한국윤활학회:학술대회논문집
• /
• 한국윤활학회 1998년도 제28회 추계학술대회
• /
• pp.343-349
• /
• 1998

A modeling of machined geometry and cutting force was proposed for the case of round shape machining, and the effects of internally machined profile are analyzed and its realiability was verified by the experiments of roundness tester, especially in boring operation in lathe. Also, harmonic cutting force model was proposed with the parameter of specific cutting force, chip width and chip thickness, and in this study, we can see that bored workpiece profile was also mapped into cutting force signal with this model. In general, we can calculated the theoretical lobe profile with arbitrary multilobe. But in real experiments, the most frequently measured numbers are 3 and 5 lobe profile in experiments. With this results, we can predict that these results may be applied to round shape machining such as drilling, boring, ball screw and internal grinding operation with the same method.

• 한국전자파학회:학술대회논문집
• /
• 한국전자파학회 2001년도 종합학술발표회 논문집 Vol.11 No.1
• /
• pp.77-81
• /
• 2001

This paper proposed a novel chip type ceramic dielectric antenna by using the advanced meander line technique that the radiational metals are formed on the face of ceramic dielectric(8 ${\times}$ 4 ${\times}$ 1.5 mm, alumina) and both facses of substrate(1.0 mm thickness, FR-4). The performance of the antenna model has a good agreements between measurements and computed results. Resultly, it has a 10 dB return-loss bandwidth(2.4～2.4835 GHz) and 1.7 dBi measured radiation gain for Bluetooth application. The proposed antenna model can overcome the problems of the radiation gain from the small antenna's size.

• Journal of Mechanical Science and Technology
• /
• 제18권3호
• /
• pp.357-369
• /
• 2004

The purposes of the paper are to analyze the fracture phenomenon by delamination and cracking when the encapsulant of plastic IC package with polyimide coating shows viscoelastic behavior under hygrothermal loading in the IR soldering process and to suggest more reliable design conditions by the approaches of stress analysis and fracture mechanics. The model is the plastic SOJ package with the polyimide coating surrounding chip and dimpled diepad. On the package without cracks, the optimum position and thickness of polyimide coating to decrease the maximum differences of strains at the bonding surfaces of parts of the package are studied. For the model delaminated fully between the chip and the dimpled diepad, C(t)-integral values are calculated for the various design variables. Finally, the optimal values of design variables to depress the delamination and crack growth in the plastic IC package are obtained.

• 한국기계가공학회지
• /
• 제5권3호
• /
• pp.29-35
• /
• 2006

Various types of elliptical motions are generated by PZT mechanism which is composed of two parallel piezoelectric actuators. Elliptical vibration cutting(EVC) is obtained by attaching single crystal diamond cutting tool to the mechanism, and V-grooving for Brass and Aluminum is carried out by applying the EVC. It is experimentally observed that the cutting force in the process of the EVC reduces compared to the ordinary non-vibration cutting, which is due to the decrease of undeformed chip thickness and frictional force between the tool and chip. Ultrasonic elliptical vibration cutting(UEVC) suppresses burr formation and decreases cutting force still more, so UEVC makes it possible to enhance the shape accuracy of machined surface.

• 한국마이크로전자및패키징학회:학술대회논문집
• /
• 한국마이크로전자및패키징학회 2002년도 추계기술심포지움논문집
• /
• pp.49-53
• /
• 2002

The Sn-Cu eutectic solder bump formation ($140{\mu}{\textrm}{m}$ diameter, $250{\mu}{\textrm}{m}$ pitch) by electroplating was studied for flip chip package fabrication. The effect of current density and plating time on Sn-Cu deposit was investigated. The morphology and composition of plated solder surface was examined by scanning electron microscopy. The plating thickness increased with increasing time. The plating rate increased generally according to current density. After the characteristics of Sn-Cu plating were investigated, Sn-Cu solder bumps were fabricated on optimal condition of 5A/dm$^2$, 2hrs. Ball shear test after reflow was performed to measure adhesion strength between solder bump and UBM (Under Bump Metallization). The shear strength of Sn-Cu bump after reflow was higher than that of before reflow.

• 한국정밀공학회지
• /
• 제12권4호
• /
• pp.135-142
• /
• 1995

Recently, the analysis of microcutting with submicrometer depth of cut is tried to get a more high quality surface product, but to get a valuable result another method instead of conventional finite element method must be considered because finite element method is impossible for a very small focused region and mesh size. As the alternative method, Molecular Dynamics or Statics is suggested and accepted in the field of microcutting, indentation and crack propagation. In this paper using Molecular Dynamics simulation, the phenomena of microcutting with subnanometer chip thickness is studied and the cutting mechanism for tool edge configuration is evaluated. As the result of simulation the atomistic chip formation is achieved.

• Journal of Animal Science and Technology
• /
• 제48권3호
• /
• pp.401-414
• /
• 2006

젖소 거세우의 육질을 개선시키기 위하여 조사료원으로서 대나무(잎과 가지포함)를 암모니아 처리 볏짚 급여수준에 대하여 4 수준(0, 30, 40, 50%)으로 나누어 체중 300kg 부터 700kg 까지 급여하면서, 증체량, 사료섭취량, 사료효율, 경제성, 소화율 및 도체특성에 미치는 영향을 조사하여 다음과 같은 결과를 얻었다. 일당증체량은 대나무 30% 급여수준은 암모니아 볏짚 급여구와 차이가 없었으나 대나무 40%와 50% 급여구는 일당증체량이 감소하였다. 농후사료섭취량은 조사료중의 대나무 급여수준에 의하여 처리구간에 큰 차이가 없었다. 조사료 섭취량은 대나무 급여수준이 높아질수록 약간씩 증가하는 경향이었다. 총 사료섭취량은 대나무 급여수준 간에 차이가 없었다. 사료효율은 대나무 30% 급여수준은 암모니아 처리 볏짚 급여구와 차이가 없었으나 대나무 40% 및 50% 수준에서는 나빠졌다. 경제성에 미치는 영향을 보면 조수익에서는 대나무 30% 급여구가 암모나아 볏짚 급여구에 비하여 약 13% 높았으나, 대나무 40%와 50% 급여구는 조수익이 낮았다. 건물, 조지방, 조단백질, 가용무질소물 및 조회분 소화율은 대나무 30% 급여구와 암모니아 처리 볏짚 급여구간에 차이가 없었으나, 조섬유 소화율은 암모니아 처리 볏짚 급여구가 대나무 급여구 보다 높았고, 대나무 급여수준 간에는 차이가 없었다. 도체율과 등지방두께는 처리구간에 차이가 없었으나 배 최장근 단면적은 대나무의 급여수준이 증가할수록 점차적으로 좁혀졌다. 육량등급은 처리구간에 같은 B 등급이었다. 육색, 지방색, 조직감, 성숙도 및 근내지방도도 처리구간에 차이가 없었고, 육질등급은 처리구간에 2 등급이었다. 그러므로 본 연구에 의하면 젖소 수소는 거세를 시키고 조사료로서 암모니아 볏짚을 급여하면서 대나무(잎과 줄기포함)를 파쇄하여 30% 정도 대체 급여하면 젖소 거세우의 소득 향상을 위해 바람직하다고 사료된다.