• Journal of Periodontal and Implant Science
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• 제48권2호
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• pp.84-91
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• 2018

Purpose: The purpose of this study was to visualize and identify peri-implant bone defects in optical coherence tomography (OCT) images and to obtain quantitative measurements of the defect depth. Methods: Dehiscence defects were intentionally formed in porcine mandibles and implants were simultaneously placed without flap elevation. Only the threads of the fixture could be seen at the bone defect site in the OCT images, so the depth of the peri-implant bone defect could be measured through the length of the visible threads. To analyze the reliability of the OCT measurements, the flaps were elevated and the depth of the dehiscence defects was measured with a digital caliper. Results: The average defect depth measured by a digital caliper was $4.88{\pm}1.28mm$, and the corresponding OCT measurement was $5.11{\pm}1.33mm$. Very thin bone areas that were sufficiently transparent in the coronal portion were penetrated by the optical beam in OCT imaging and regarded as bone loss. The intraclass correlation coefficient between the 2 methods was high, with a 95% confidence interval (CI) close to 1. In the Bland-Altman analysis, most measured values were within the threshold of the 95% CI, suggesting close agreement of the OCT measurements with the caliper measurements. Conclusions: OCT images can be used to visualize the peri-implant bone level and to identify bone defects. The potential of quantitative non-invasive measurements of the amount of bone loss was also confirmed.

• 대한기계학회논문집A
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• 제38권12호
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• pp.1351-1358
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• 2014

본 논문은 차량 제동 시 발생하는 소음의 원인을 해석적으로 예측하고, 본 실험실에서 제작한 브레이크 다이나모 메터를 이용하여 실험적으로 검증하였다. 압력 변화에 따른 브레이크 시스템에 대한 주파수 응답 시험 및 유한 요소 해석(FEM)을 실시하여 캘리퍼 및 디스크의 수직 모드(Out-of-plane)의 시스템 주파수를 추적하였다. 이를 제동 시 발생한 스퀼 소음의 주파수와 비교해본 결과 스퀼 주파수는 캘리퍼 및 패드의 변위를 갖는 시스템 모드임을 확인하였다. 또한 유한 요소 해석을 이용한 복소수 고유치 해석 결과 패드의 회전변위를 발생시키는 캘리퍼 모드가 음의 마찰곡선 기울기와 연동하여 불안정하게 됨을 확인하였다.

• 비파괴검사학회지
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• 제35권4호
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• pp.245-250
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• 2015

MoC(motor on caliper)를 이용한 자동차 브레이크 시스템이 장착되었을 때 도로 조건에 의해 발생하는 진동으로 래틀 소음 발생 가능성을 검증하기 위하여, 무향실에서 가진기(quiet shaker)를 이용하여 차량상태와 동일한 진동을 인가하면서 소음을 동시에 측정하여 실제 운행 중에 발생하는 MoC 래틀 소음을 재현하였다. 소음 발생 조건 및 원인을 파악하는 신호 처리 방법을 제안하였다. 원리 시험을 통해서 충돌되는 두 부품 간의 고유 진동수를 확인하고, 소음이 발생할 때의 음압/진동 신호의 임팩트성 소음에 대해 주파수 성분을 분석하여 소음 발생 빈도에 영향을 줄 수 있는 인자를 찾는 방법을 제안하였다. 더불어 래틀 소음을 분석하기 위한 FFT 주파수 분석을 실시하고 장단점을 분석하였으며, 단점을 보완하기 위한 프로니 분석 방법에 대해서 실제 두 가지 다른 브레이크 시스템의 내구 테스트 결과에 적용하여 효율성을 입증하였다.

• Imaging Science in Dentistry
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• 제46권2호
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• pp.93-101
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• 2016

Purpose: The objective of this study was to investigate the effect of varying resolutions of cone-beam computed tomography images on the accuracy of linear measurements of edentulous areas in human cadaver heads. Intact cadaver heads were used to simulate a clinical situation. Materials and Methods: Fiduciary markers were placed in the edentulous areas of 4 intact embalmed cadaver heads. The heads were scanned with two different CBCT units using a large field of view ($13cm{\times}16cm$) and small field of view ($5cm{\times}8cm$) at varying voxel sizes (0.3 mm, 0.2 mm, and 0.16 mm). The ground truth was established with digital caliper measurements. The imaging measurements were then compared with caliper measurements to determine accuracy. Results: The Wilcoxon signed rank test revealed no statistically significant difference between the medians of the physical measurements obtained with calipers and the medians of the CBCT measurements. A comparison of accuracy among the different imaging protocols revealed no significant differences as determined by the Friedman test. The intraclass correlation coefficient was 0.961, indicating excellent reproducibility. Inter-observer variability was determined graphically with a Bland-Altman plot and by calculating the intraclass correlation coefficient. The Bland-Altman plot indicated very good reproducibility for smaller measurements but larger discrepancies with larger measurements. Conclusion: The CBCT-based linear measurements in the edentulous sites using different voxel sizes and FOVs are accurate compared with the direct caliper measurements of these sites. Higher resolution CBCT images with smaller voxel size did not result in greater accuracy of the linear measurements.

• 음성과학
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• 제8권3호
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• pp.161-172
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• 2001

Ankyloglossia (tongue-tie) limits movement of the tongue connected with feeding and has adverse impacts on both dental health and speech. For the patients with ankyloglossia, surgical intervention is recommended as primary treatment. This study suggests the efficient tool in determining indicatory factors for frenulotomy by quantifying Maximum Lingual Length-Protrusion (MLL-P) with boley gauge, and as a preliminary study, to show the measurement results with normal children using the tool. The subjects were 61 normal children, and the distance (MLL-P) between mandibular central incisor and tongue tip during tongue protrusion was measured with a boley gauge (Digimatic $Caliper^{(R)}$). The results of this study can be summarized as follows: (1) The mean value of MLL-P (N=61 normal children) was 21.44 mm, (2) The mean value of MLL-P was 20.69 mm in males (N=33) and 21.91 mm in females (N=28). There was no statistically significant difference between males and females, (3) The mean value of MLL-P was 19.34 mm, 21.19 mm, 22.33 mm, 22.61 mm for measurement of 3-, 4-, 5- and 6-year-old children, respectively, and (4) The mean value of MLL-P showed statistically significant difference between 3- and 5-year-old children, between 3- and 6-year old children.

• Tribology and Lubricants
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• 제27권5호
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• pp.269-274
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• 2011

The purpose of this paper is to study and analyze the improvement method for the failure examples including the vehicle brake system in actual field. It was verified that the indicator plate of pad wear scratched the brake disk because of wearing after displacement of non- identification parts pad. The caliper of other vehicle was installed with brake system verified the phenomenon produced groove in center point because of one side wear when the pad was not fully contacted with the rub disk by other action surface pressure and pad action condition. It verified that the crack phenomenon fatigue was produced by brake thermal deformation because of decreasing the thickness by grinding to modify the non-uniformed wear of brake disk. It verified that the friction sound was produced by the friction phenomenon because of non-uniformed contact of lining and an alien substance with inner of the drum and lining braking by crack phenomenon with brake drum surface.

• 한국자동차공학회논문집
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• 제16권1호
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• pp.166-174
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• 2008

Recently, the automotive industry has been developing rapidly. With the progress parts of the automobile components need high quality and the reliability. Among them, braking unit is essential device, and acquire the reliability through the performance test of brake. This study was aimed to design the performance-test-bench to measure the drag torque which has effect on caliper in braking unit. In this progressive technology, it is vital importance to use hydraulic and pneumatic, and to combine test bench with instrumentation engineering technology. This system to construct the design of hydraulic and pneumatic circuit, interface technique between sensors and personal computer, data acquisition and display design, and integrated control are very important technology. Moreover, reliable data are obtained through vacuum system and hydraulic and pneumatic system by using of booster and brake master cylinder which are actually applied to automobile. Then, data signal detector sensors for speed, pressure and torque is attached on this system. Therefore, in this study, we designed a performance-test-bench by and we also made an total control system using personal computer which is more progressive and flexible method than existing PLC control.

• 한국자동차공학회논문집
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• 제25권1호
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• pp.19-27
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• 2017

In this paper, a simulator hardware and control design for an electronic parking brake (EPB) are proposed for emergency vehicle braking when the hydraulic break and anti-lock brake systems (ABS) fail to function. EPB systems are designed specifically for park braking and are usually installed on the rear wheels. However, in an emergency situation when all vehicle brake systems fail, the EPB can be utilized to stop the vehicle and track the target slip ratio as the ABS. This paper analyzed the non-linear EBP of the type of motor on caliper (MoC) based on experiments. A simulator hardware is also designed to validate the performance of the designed EPB controller in terms of braking distance and performance in tracking the target slip ratio. Through the experimental analysis, it is confirmed that a sliding mode controller can be applied on a non-linear EPB to track the target slip ratio.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 춘계학술대회논문집
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• pp.607-612
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• 2004

Disc brake noise continues to be a major concern throughout the automotive industry despite efforts to reduce its occurrence. Eliminating vibrations during braking is an important task for both vehicle passenger comfort and reducing the overall environmental noise levels. There are several classes of disc brake noise, the major ones being squeal, judder, groan, and moan. In this study, analytical model for moan noise of rear disk brake is investigated. Modeling of the disc brake assembly to take account of the effect of different geometrical and contact parameters is studied through the use of multi-body model. The contact stiffness of the caliper and torque member plays an important role in controlling brake vibration. Therefore, a suitable material pair at the caliper/body contact has been made. An ADAMS model of a rear disc brake system was integrated with a flexible suspension trailng arm from MSC/NASTRAN. A fully non-linear dynamic simulatin of brake system behavior, containing rigid and flexible bodies, was performed for a Prescribed set of operating conditions. Simulation results were validated using data from vehicle experimental testing.

• Journal of Mechanical Science and Technology
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• 제17권5호
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• pp.629-636
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• 2003

This paper introduces the developed geometry PIG (Pipeline Inspection Gauge), one of several ILI (In-Line Inspection) tools, which provide a full picture of the pipeline from only single pass, and has compact size of the electronic device with not only low power consumption but also rapid response of sensors such as calipers, IMU and odometer. This tool is equipped with the several sensor systems. Caliper sensors measure the pipeline internal diameter, ovality and dent size and shape with high accuracy. The IMU (Inertial Measurement Unit) measures the precise trajectory of the PIG during its traverse of the pipeline. The IMU also provide three-dimensional coordination in space from measurement of inertial acceleration and angular rate. Three odometers mounted on the PIG body provide the distance moved along the line and instantaneous velocity during the PIG run. The datum measured by the sensor systems are stored in on-board solid state memory and magnetic tape devices. There is an electromagnetic transmitter at the back end of the tool, the transmitter enables the inspection operators to keep tracking the tool while it travels through the pipeline. An experiment was fulfilled in pull-rig facility and was adopted from Incheon LT (LNG Terminal) to Namdong GS (Governor Station) line, 13 km length.