• 한국터널지하공간학회 논문집
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• 제16권6호
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• pp.585-597
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• 2014

본 연구에서는 받음각이 $45^{\circ}$인 경우에 대해 사각이 $0^{\circ}$와 $6^{\circ}$이고 S/d비가 1.3~12사이인 시험조건에 대해 슬림 코니컬커터를 사용하여 선형절삭시험동안 발생하는 커터작용력을 측정하였다. 각 시험조건에서 커터작용력인 연직력, 절삭력, 구동력을 측정하였고 그 측정결과의 평균값을 사용하여 분석을 실시하였다. 커터관입깊이가 깊어질수록 비에너지가 감소하였고 커터관입깊이에 따른 커터작용력의 변화는 사각이 $6^{\circ}$인 경우가 작게 나타났다. 이와 같은 결과로부터 사각이 $6^{\circ}$인 경우가 $0^{\circ}$인 경우에 비해 장비설계측면에서 효과적인 것으로 판단된다. 또한 $F_c/F_n$은 사각이 $6^{\circ}$일 때가 $0^{\circ}$인 경우에 비해 작게 나타났다. 그러나 사각이 있을 경우 구동력의 증가가 나타날 수 있으므로 이에 대한 고려가 필요하다.

• 대한기계학회논문집A
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• 제27권8호
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• pp.1309-1316
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• 2003

The general dicing process cuts a semiconductor wafer to lengthwise and crosswise direction by using a rotating circular diamond blade. But products with inferior quality are produced under the influence of several parameters in dicing process such as blade, wafer, cutting water and cutting conditions. Moreover we can not apply this dicing method to GaN wafer, because the GaN wafer is harder than the other wafer such as SiO2, GaAs, GaAsP, and AlGaAs. In order to overcome this problem, development of a new dicing process and determination of dicing parameters are necessary. This paper describes a new wafer dicing method using fixed diamond scriber and precision servo mechanism and determination of several parameters - scribing depth, scribing force, scriber inclined angle, scribing speed, and factor for scriber replacement - for a new dicing machine using scriber.

• 한국정밀공학회지
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• 제20권2호
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• pp.218-225
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• 2003

The general dicing process cuts a semiconductor wafer to lengthwise and crosswise direction by using a rotating circular diamond blade. However, inferior goods may be made under the influence of several parameters in dicing process such as blade, wafer, cutting water and cutting conditions. Moreover we can not apply this dicing method to a GaN wafer, because the GaN wafer is harder than other wafers such as SiO$_2$, GaAs, GaAsP, and AlGaAs. In order to overcome this problem, development of a new dicing process and determination of dicing parameters are necessary. This paper describes determination of several parameters - scribing depth, scribing force, scriber inclined angle, scribing speed, and factor for scriber replacement - for a new dicing machine using a scriber.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.164-167
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• 2002

The general dicing process cuts a semiconductor wafer to lengthwise and crosswise direction by using a rotating circular diamond blade. But inferior goods are made under the influence of several parameters in dicing process such as blade, wafer, cutting water and cutting conditions. Moreover we can not applicable this dicing method to GaN wafer, because the GaN wafer is harder than the other wafer such as SiO$_2$, GaAs, CaAsP, and AlCaAs. In order to overcome this problem, development of a new dicing process and determination of dicing parameters are necessary. This paper describes determination of several parameters - scribing depth, scribing force, scriber inclined angle, scribing speed, and factor for scriber replacement - for a new dicing machine using scriber.

• 한국운동역학회지
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• 제26권4호
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• pp.433-441
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• 2016

Objective: The purpose of this study was to understand the injury mechanism and to provide quantitative data to use in prevention or posture correction training by conducting kinematic and kinetic analyses of risk factors of lower extremity joint injury depending on the change of direction at different angles after a landing motion. Method: This study included 11 men in their twenties (age: $24.6{\pm}1.7years$, height: $176.6{\pm}4.4cm$, weight: $71.3{\pm}8.0kg$) who were right-leg dominant. By using seven infrared cameras (Oqus 300, Qualisys, Sweden), one force platform (AMTI, USA), and an accelerometer (Noraxon, USA), single-leg drop landing was performed at a height of 30 cm. The joint range of motion (ROM) of the lower extremity, peak joint moment, peak joint power, peak vertical ground reaction force (GRF), and peak vertical acceleration were measured. For statistical analysis, one-way repeated-measures analysis of variance was conducted at a significance level of ${\alpha}$ <.05. Results: Ankle and knee joint ROM in the sagittal plane significantly differed, respectively (F = 3.145, p = .024; F = 14.183, p = .000), depending on the change of direction. However, no significant differences were observed in the ROM of ankle and knee joint in the transverse plane. Significant differences in peak joint moment were also observed but no statistically significant differences were found in negative joint power between the conditions. Peak vertical GRF was high in landing (LAD) and after landing, left $45^{\circ}$ cutting (LLC), with a significant difference (F = 9.363, p = .000). The peak vertical acceleration was relatively high in LAD and LLC compared with other conditions, but the difference was not significant. Conclusion: We conclude that moving in the left direction may expose athletes to greater injury risk in terms of joint kinetics than moving in the right direction. However, further investigation of joint injury mechanisms in sports would be required to confirm these findings.

• 한국통신학회논문지
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• 제19권1호
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• pp.120-130
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• 1994

전자기기 생산시 기관에 부품을 장착하고 기판 뒷면의 리드선을 절단할 때, 현재까지는 회전절단기를 사용했었는데, 이 방법에서는 한쪽 방향에서만 힘을 가하여 절단함으로써 접촉불량의 한 원인이 되곤 했다. 특히 양면에 부품을 장착하는 경우나 유연한 기관이나 정밀을 요구하는 경우, 부품의 리드선이 매우 굵은 경우에는 사람의 손으로 일일이 절단해야 했다. 그래서 로봇팔을 이용하여 니퍼로 절단하는 방법이 도입되기 시작하였는데, 절단할 리드선의 위치를 하나하나 입력시켜 주어야 했다. 본 논문에서는 여러 방향에서 입력되는 정면도로써 절단할 리스선의 좌표를 구해 내는 방법을 제안하고, 시뮬레이션과 실험을 통하여 실현가능성을 확인하였다. 저가의 감시용 CCD카메라를 이용하여 실험한 결과 88.81%가 1mm이하의 오차를 가졌는데, 적응성 공기압니퍼를 이용한 경우 절단이 가능한 범위ㅣ내이었다. 더욱 정밀한 카메라 및 측정환경을 갖춘다면 본 논문에서 제안하는 방법으로 매우 정밀하게 측정이 가능하리라 사료된다.

• 한국기계가공학회지
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• 제21권2호
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• pp.137-143
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• 2022

Composite materials, being light-weight and of high mechanical strength, are increasingly used in various industries such as the aerospace, automobile, sporting-goods manufacturing, and ship-building industries. Recently, manufacturing of composite materials using 3D printers has increased. 3D-printed composite materials are made in free-form and adapted for end-use by adjusting the fiber content and orientation. However, research on the machining of 3D printed composite materials is limited. The aim of this study is to develop a machine learning method to select machining conditions for machining of 3D-printed composite materials. The composite material was composed of Onyx and carbon fibers and stacked sequentially. The experiments were performed using the following machining conditions: spindle speed, feed rate, depth of cut, and machining direction. Cutting forces of the different machining conditions were measured by milling the composite materials. PCA, a method of machine learning, was developed to select the machining conditions and will be used in subsequent experiments under various machining conditions.

• 대한조선학회논문집
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• 제31권1호
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• pp.121-132
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• 1994

본 연구에서는 선저보강판부재의 좌초시 손상거동특성을 규명하기 위하여 시리즈 실험을 수행하였다. 즉, 강체웨지가 선저보강판을 연직방향에서 준정적으로 진입할 때 여러가지 파라메타 즉 1) 판의 종횡비, 2)웨지각도, 3)판두께, 4)웨지형상 및 5)종 횡보강재의 변화에 따른 시리즈 실험을 수행하고, 좌초시 선저보강판의 좌초하중-진입량 관계와 흡수에너지-진입량 관계 등에 관한 파라메타들의 영향을 분석하였다.

• 한국정밀공학회지
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• 제13권7호
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• pp.158-166
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• 1996

In this study, a flexible disk grinding process is applied in order to produce high precision product. A new model was developed considering feed motion along horizontal and vertical direction. Different types of feed speed variation was tested with respect to distinct process stages in order to achieve flat surface. It was observed that highest order polynomial form for both horizontal and vertical feed speed variation among the proposed categories produced surface close to flat one. Disk deflection trend during the process was visualized confirming the proposed scheme. Cutting force and VRR(volume removal rate) was observed as an aid to process planning.

• 대한치과기공학회지
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• 제9권1호
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• pp.51-55
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• 1987

One of the primary advantages of acrylic resin teeth is their ability to bond chemically to the denture base resins. Fracture od acrylic resin teeth from a maxillary denture, however, is not uncommon. Bonding failures have been attributed to faulty boil-out procedures that fail to eliminate all traces of wax from the ridge lap surfaces of the teeth and to contamination of the ridge lap surface by careless application of tinfoil substitute. Attempts to increase the strength of the bond between acrylic resin teeth and heat-cured denture base resin include grinding the glossy ridge lap surface (in fluid system), painting the ridgelap surface of the teeth with monomer-polymer solution, and cutting retention grooves in the ridge lap surface of the teeth. This latter method has been tested by applying a tensile force in a labial direction to the incisal part of the lingual surface of the acrylic resin teeth. A progressive shear compressive load was applied at an angle to the lingual surface of acrylic resin teeth bonded to denture base acrylic resin. No statistically singificant advantage was derived by preparing retention grooves of different shapes in the ridgelap surface of the denture teeth.