• 대한기계학회논문집A
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• 제29권11호
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• pp.1542-1550
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• 2005

This paper presents the numerical procedure for calculating non-uniform residual stresses based on relieved displacements obtained from incremental hole drilling. The relationship between the in-plane displacement produced by introducing a blind hole and the corresponding residual stress is established. Finite element calculations are described to evaluate the relieved coefficients required for the determination of non-uniform residual stresses. Validity of the proposed method has been tested through three axisymmetric test examples and two three-dimensional examples. As a result of . simulation on the test examples, it is found that this numerical procedure is well adopted to measuring non-uniform residual stress in the full hole depth range of the hole diameter from the surface. The accuracy of the hole drilling method with displacement measurement is discussed, comparing tile method with strain measurement

• 한국정밀공학회지
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• 제25권1호
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• pp.79-84
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• 2008

For the precision measurement of industrial products, the location of holes inside the products, if they exist, are often selected as feature points. The measurement of hole location would be performed by vision and laser-vision sensor. However, the usage of those sensors is limited in case of big change of light intensity and reflective shiny surface of the products. In order to overcome the difficulties, we have developed a hole displacement measuring device using contact-type displacement sensors (LVDTs). The developed measurement device attached to a robot measures small displacement of a hole by allowing its X-Y movement due to the contact forces between the hole and its own circular cone. The developed device consists of three plates which are connected in series for its own function. The first plate is used for the attachment to an industrial robot with ball-bush joints and springs. The second and third plates allow X-Y direction as LM guides. The bottom of the third plate is designed that various circular cones can be easily attached according to the shape of the hole. The developed system was implemented for its effectiveness that its measurement accuracy is less than 0.05mm.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 추계학술대회 논문요약집
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• pp.180-180
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• 2003

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.127-130
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• 2004

For the quality control of the industrial products, an automatic hole measuring system has been developed. The measurement device allows X-Y movement due to contact forces between a hole and its own circular cone and the device is attached to an industrial robot. Its measurement accuracy is about 0.04mm. This movement of the plate is measured by two LVDT sensor system. But this system using the LVDT sensors is restricted by high cost and precision of measurement and correspondence of environment so particularly, a vision system with CCD-Camera is discussed in this paper for the above mentioned purpose. The device consists of two of two links jointed with hinge pins basically and, they guarantee free movement of the touch prove attached on the second link in the same plane. These links are returned to home position by the spring plungers automatically after each process for the next one. On the surface of the touch prove, it has a circular white mark for camera recognition. The system detect and notify the center coordinate of capture mark image through the image processing. Its measuring accuracy has been proved to be about $\pm$0.01mm through the repeated implementation over 200 times. This technique will shows the advantage of touch-indirect image capture idea using cone-shaped touch prove in various symmetrical shaped holes particulary, like tapped holes, chamfered holes, etc As a result, we attained our object in a view of the accuracy, economical efficiency, and functionality

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.1195-1198
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• 2003

Micro former has been known as a useful tool for machining micro parts. It makes micro holes automatically with punches, a hole-shape die and material by rotation of crank shaft synchronously. Micro displacement in micro forming affects on the performance of machining because micro forming size is similar with its mechanical displacement. Therefore, the measurement of this micro displacement is essential to be guaranteed to obtain high forming precision in the whole machine as well as its devices. This paper addresses the development of a laser interferometer to measure micro displacement for a micro former. The laser interferometer is able to measure micro displacement during a few micro seconds with non-contact. For the experiment, a laser probe is installed on the optical table with optical devices and a micro displacement generating device. The velocity decoding board is also added to calculate doppler shift frequency directly. Finally simple experiments are conducted to confirm its functional operation.

• 한국정밀공학회지
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• 제33권2호
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• pp.121-128
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• 2016

The mechanical jointing method is very important in the machine parts and structure. They are used by the bolts and rivet because it is very convenient to replace the parts and the structure. However, the mechanical jointing methods using the bolt and rivet needed the open hole. The machine parts life cycle is reduced because this open hole created the stress concentration. Therefore, the measurement methods are needed to evaluate phenomenon of the stress concentration. This paper discusses the development of the measurement algorithm using the digital image correlation methods to measure the strain distribution of the open hole. To implement the measurement algorithm using the DIC, the LabVIEW 2010 programming tool was used. To measure the strain distribution of the open hole, the tensile specimens having an open hole are made by using the aluminum 6061-T6. To secure the reliability of measurement result using the DIC, the DIC measurement results and FEM analysis results were compared.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 춘계학술대회 논문집 디스플레이 광소자분야
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• pp.96-99
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• 2003

본 논문에서는 수치 해석 방법을 이용하여 $In_{x}Ga_{1-x}N/GaN$ (x=0.06~0.1) 양자우물 구조의 에너지 준위를 계산하였다. InGaN 벌크 샘플(bulk sample)의 PL(photoluminescence) 데이터로부터 bowing factor를 결정한 후 InGaN의 유효 에너지 밴드갭을 계산하였고, InGaN/GaN 양자우물 구조의 전도대와 가전자대의 오프셋(offset)을 0.67/0.33으로 정하였다. 다음으로, 양자화 효과에 의한 에너지 변위와 압전장(piezoelectric field)을 제외한 양축 압축 변형(biaxial compressive strain)에 의한 에너지 변위를 고려하여 기저준위 전자와 heavy hole(le-1hh)간의 천이 에너지를 계산하였다. 계산된 천이 에너지는 PL로 측정한 천이 에너지에 비해 약 9~15 meV 크게 관찰되었는데, 이것은 InGaN/GaN 양자우물 계면에 발생하는 압전장 때문인 것으로 생각된다.

• 대한정형외과학회지
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• 제55권1호
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• pp.71-77
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• 2020

목적: 요추부 척추관 협착증에서의 후방 감압술 시 극간인대 및 극상인대의 보존이 술 후 척추 불안정성의 예방에 미치는 영향에 대하여 밝히고자 했다. 대상 및 방법: 2014년 3월부터 2017년 3월까지 요추부 척추관 협착증에서 후방 감압술을 시행하고 1년 이상 추시관찰한 83명의 환자를 후향적으로 연구하였다. 대상자들을 수술의 종류에 따라 포트홀 감압술을 시행한 56명의 환자는 그룹 A로, 후궁 아전절제술을 시행한 27명의 환자는 그룹 B로 분류하였다. 임상적 결과를 평가하기 위해 Oswestry disability index (ODI), 요통과 방사통에 대한 시각통증점수(visual analogue scale, VAS), 신경성 간헐적 파행(neurogenic intermittent claudication, NIC) 전 보행거리가 수술 전후로 측정되었다. 영상의학적 결과를 평가하기 위해 수술 전 및 수술 후 매 6개월마다 직립상태에서 측면 및 굴곡-신전 단순 방사선 사진을 촬영해 전위 정도(slip percentage), 역동적 전위 정도(dynamic slip percentage), 각변위(angular displacement), 역동적 각변위(dynamic angular displacement)를 측정하였다. 결과: ODI (그룹 A에서 28.1에서 12.8로 호전; 그룹 B에서 27.3에서 12.3으로 호전), 요통에 대한 VAS (그룹 A에서 7.0에서 2.6로 호전; 그룹 B에서 7.7에서 3.2로 호전), 방사통에 대한 VAS (그룹 A에서 8.5에서 2.8로 호전; 그룹 B에서 8.7에서 2.9로 호전), 그리고 NIC 전 보행 거리(그룹 A에서 118.4 m에서 1,496.2 m로 증가; 그룹 B에서 127.6 m에서 1,481.6 m로 증가)는 두 그룹 모두에서 호전되었다. 다른 영상의학적 결과들에서 유의한 차이가 없었던 반면 역동적 각변위는 술 후 두 그룹간에 유의한 차이를 보였다(그룹 A에서 6.2°에서 6.7°로 증가; 그룹 B에서 6.5°에서 8.4°로 증가; p-value=0.019). 결론: 요추부 척추관 협착증에서의 후방 감압술시 극간인대 및 극상인대를 포함한 후방 인대의 제거는 술 후 역동적 각변위의 증가를 초래하며 후방 인대를 보존하는 포트홀(port-hole) 감압술을 통해 이를 예방할 수 있다.

• 한국정밀공학회지
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• 제21권7호
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• pp.145-152
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• 2004

This paper proposed efficient manufacturing system using the OMM (on-machine measurement) system. The OMM system is software based 3D modeler for inspection on machine and it is interfaced tool machine with RS232C. The software is composed of two inspection modules that one is touch probe operating module and the other is laser displacement sensor operating module. The module for touch probe has need of inspection feature that extracted it from CAD data. Touch probe moves to workpiece by three operating modes as follows: manual, general and automatic mode. The operating module of laser displacement sensor is used inspection for profile and very small hole. An Advantage of this inspection method is to be able to execute on-line inspection during machining or after it. The efficiency of proposed system which can predict and definite the machining errors of each process is verified, so the developed system is applied to inspect the mold-base(cavity, core).

• 한국지반공학회논문집
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• 제39권6호
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• pp.21-30
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• 2023

현장타설말뚝의 연암 근입부의 단위주면마찰력을 산정하는 방법 중 암반 벽면거칠기에 의한 산정 방법이 있다. 현장타설말뚝의 굴착 시공 시 암반 굴착공에 거칠기 장치를 설치하고 벽면 거칠기 모양을 측정하고 그 결과를 이용하여 주면마찰력을 산정하는 것이다. 본 연구에서는 암반벽면의 거칠기를 직접 측정한 결과와 하중전이 시험결과를 비교분석하여 거칠기시험에 의한 단위주면마찰력을 말뚝의 발생 변위에 대응하는 단위 주면마찰력으로 변환할 수 있도록 저감계수 R_f = -0.14n + 1.48(여기서, n은 하중전이시험에서 도출된 발생변위 δ를 말뚝직경 D로 나눈 변위비)을 제안하였다.