• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1998년도 추계학술대회
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• pp.167-168
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• 1998

The purpose of this study is to verify the biomechanical characteristics of the custom-made(our) pedicle screws which are designed the different types of shape, pitch, and profile. The results of experiments for our pedicle screw were summarized. 1) The screw of larger outer diameter showed greater holding strength. 2) The holding strength of cylindrical shaped screw was superior to that of conical shaped screw. 3) The holding strength of buttress shape of thread profile showed superior to that of V-shape. 4) The pull out and holding strength of our pedicle screws was superior to that of commercialized screw (Diapason and CD) which is widely used.

• Archives of Pharmacal Research
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• 제18권5호
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• pp.314-319
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• 1995

Antacid granules were prepared by agglomeration and powder method in high speed agitation type granulator. The copmositions of the test antacids were sodium bicarbonate nad magnesium carbonate nad a coating material was powder of polyvinylacetal diethyl-aminocacetate (AEA) and an additive material was talc powder. The dissolution characteristics of base from the antacid granules were investigated to evaluate neutralization capacity of hydrochloric profile of base and neutralization behavior, the following results were obtained : The prepared granules showed a pH-dependent dissolution pattern of a base. The dissolution profile of a base was varied with addition of talc powder as well as coating amount of AEA. The relationship between the ratio of dissolution retarded time for 20% and 10% AEA. The relationship between the ratio of dissolution retarded time for 20% AEA coated granules $\theta_{20}/\theta_{10}$ and the diameter reduction of the granules was explained by the rate process of neutralization of hydrochloric acid.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2002년도 추계학술대회 논문집
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• pp.462-467
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• 2002

New methods for screw and spline production has been developed recently by Japan and other developed countries in the basis of Rolling Dies work to cut down the production cost. These methods give us high precision of the products. But we in Korea mostly import Dies for manufacturing forming products. It is thought that if we don't develop our own technology for Rolling Dies, we will have to spend much money for importing Forming concerned equipments. In this paper, we designed the rolling dies based on the diameter of material and calculated the proper number of teeth of gear to establish desirable method for Rolling dies. And the result is shown after manufacturing Involute spline with the rolling dies.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1999년도 춘계학술대회 논문집
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• pp.240-244
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• 1999

This paper deals with the establishment of the cutting direction on inclined plane by using ball end mill. Ball-end milling is widely used for free form surface die and mold. In these machining, the cutting parts vary because the tool tip is hemisphere shaped. The cutting characteristics, such as cutting force, surface roughness and surface profile are varied according to the variation of cutting directions. The effective tool diameter was calculated on different tilt angles and tool-path. Tool life and cutting characteristics were estimated on variation of cutting directions in the same cutting speed. In this paper, the optimal cutting direction which can be applied 3-D sculpture surface cutting is suggested.

• International Journal of Railway
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• 제6권4호
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• pp.148-154
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• 2013

This article has tried to review the maximum contact stresses in the contact area of the wheel and rail as a result of lateral movement of the wheel on rail by taking advantage from Hertz theory. Since wheel movement on rail is accompanied by lateral movement due to wheel profile conisity, so the contact point of wheel and rail is not constant and the contact stresses are therefore changeable in every single moment. Since the shape of rail profile and rail inclination, wheel diameter and the mechanical properties of the wheel and rail are effective on the stresses of contact area, these parameters have been studied by applying Hertz theory. This article aims to calculate the contact stresses in different parts on the wheel surface by using Hertz theory.

• International Journal of Ocean Engineering and Technology Speciallssue:Selected Papers
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• 제3권1호
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• pp.40-48
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• 2000

The term "deep holes" is used to describe the machining of holes with a relatively large length to diameter ratio. The main feature of BTA deep hole drilling is the stabilization of cutting force necessary for the self guidance of the drill head. An additional feature is the cutting tool edges that are unsymmetrically placed on the drill head. There is an increasing necessity to predict the hole geometry and other dynamic stability behavior of deep hole drilling guidance. In this study, the effects of BTA deep hole drilling conditions on the hole profile machined piece are analyzed using domain analysis technique. The profile of deep hole drilled work piece is related to cutting speed, feed rate, chip flow, tool wear, and so on. This study deals with the experimental results obtained during the BTA drilling on SM45C, SM55C carbon steels and SCM440 steels under various cutting conditions, and these results are compared with analytical evaluations.aluations.

• 분석과학
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• 제10권5호
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• pp.357-361
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• 1997

Griemm 형태의 글로우방전셀을 상업용 사중극자 ICP-MS에 장착시켜 다층박막의 표면 분석을 시도하였다. 지름이 2.0mm인 양극과 적절한 실험 최적 조건을 사용한 결과 ${\mu}m$ 두께의 여러층들을 30여 분 이내에 분석할 수 있었다. Cu-Ni 및 Fe-Ni의 다층막을 GDMS로 분석한 결과 10nm정도의 분해능이 가능하였으며, 이는 바닥이 평평한 crater를 얻을 수 있는 실험조건에서 측정하였기 때문이다.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2004년도 유체기계 연구개발 발표회 논문집
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• pp.572-577
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• 2004

This paper presents numerical study on the performance improvement of the sirocco fan in a range hood. The performance of sirocco fan means a higher flowrate, a higher static pressure and a lower required motor power in a fixed geometry constraint. Various impeller geometric parameters, such as blade profile, blade diameter, blade thickness profile and blade exit angle, were investigated by numerically and the results were compared with each other to know the effects on the performance. In this approach, the volute geometry were fixed with the original shape. The numerical results show that the blade profile with airfoil shape and small exit blade thickness increases the performance. The blade exit angle shows optimum angle within a varied range. The efficiency of the optimized exit angle was about $10\%$ higher than the base blade exit angle and the static pressure was about $28\%$ higher at the flow coefficient 0.22.

• Nuclear Engineering and Technology
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• 제48권1호
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• pp.200-210
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• 2016

The neutron radiography reactor (NRAD) is a 250 kW Mark-II Training, Research, Isotopes, General Atomics (TRIGA) reactor at Idaho National Laboratory, Idaho Falls, ID, USA. The East Radiography Station (ERS) is one of two neutron beams at the NRAD used for neutron radiography, which sits beneath a large hot cell and is primarily used for neutron radiography of highly radioactive objects. Additional fuel elements were added to the NRAD core in 2013 to increase the excess reactivity of the reactor, and may have changed some characteristics of the neutron beamline. This report discusses characterization of the neutron beamline following the addition of fuel to the NRAD. This work includes determination of the facility category according to the American Society for Testing and Materials (ASTM) standards, and also uses an array of gold foils to determine the neutron beam flux and evaluate the neutron beam profile. The NRAD ERS neutron beam is a Category I neutron radiography facility, the highest possible quality level according to the ASTM. Gold foil activation experiments show that the average neutron flux with length-to-diameter ratio (L/D) = 125 is $5.96{\times}10^6n/cm^2/s$ with a $2{\sigma}$ standard error of $2.90{\times}10^5n/cm^2/s$. The neutron beam profile can be considered flat for qualitative neutron radiographic evaluation purposes. However, the neutron beam profile should be taken into account for quantitative evaluation.

• 한국정밀공학회지
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• 제11권6호
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• pp.28-41
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• 1994

An efficient algorithm is proposed to select the proper tools and generate their paths for NC rough cutting of dies and molds with sculptured surfaces. Even though a milling process consists of roughing, semi-finishing, and finishing, most material is removed by a rough cutting process. Therfore it can be said that the rough cutting process occupy an important portion of the NC milling process, and accordingly, an efficient rough cutting method contributes to an efficient milling process. In order work, the following basic assumption is accepted for the efficient machining. That is, to machine a region bounded by a profile, larger tools should be used in the far inside and the region adjacent to relatively simple portion of the boundary while smaller tools are used in the regions adjacent to the relatively complex protion. Thus the tools are selected based on the complexity of the boundary profile adjacent to the region to be machined. An index called cutting path ratio is proposed in this work as a measure of the relative complexity of the profile with respect to a tool diameter. Once the tools are selected, their tool paths are calculated starting from the largest to the smallest tool.