• 설비공학논문집
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• 제24권1호
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• pp.1-8
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• 2012

Recently, the needs of system performances such as working speed and processing accuracy in machine tools have been increased. Especially, the speed increment generates harmful heat at both moving part of the machine tools and handicrafts. The heat is a main drawback to progress accuracy of the processing. Hence, a cooler system to control temperature is inevitable for the machine tools. In general, two representative control schemes, hot-gas bypass and variable speed control of a compressor, have been adopted in the water cooler system. In this paper, comparisons of system performances according to the control schemes in a cooler for machine tools were conducted in detail. Each proportional-integral feedback controller for the two different control systems is designed. The system performances, especially the temperature control accuracy and coefficient of performance which is a criterion of energy saving, were mainly analyzed through various experiments using 1RT water cooler system with different two types of control scheme. These evaluations will provide useful information to choose suitable water cooler system for the engineers who design controllers of the cooler system for machine tools.

• 한국측량학회지
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• 제30권6_1호
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• pp.511-518
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• 2012

비측정용 카메라를 이용하여 근거리 사진측량을 수행하기 위해서는 카메라 캘리브레이션이 필요하며 근거리 사진측량의 특성상 캘리브레이션은 정밀 기준점의 설치, 다수의 영상획득, 정밀 좌표측정과 더불어 많은 시간이 소요된다. 따라서 본 연구에서는 실제 캘리브레이션 필드를 대상으로 기준점의 개수, 배치, 사진조합에 따른 오차를 분석하여 효율적인 캘리브레이션 방법을 모색하는 연구를 수행하였다. 기준점의 기복과 사진 조합의 관계가 측량 정확도에 미치는 영향, 그리고 기준점 수와 모델링하고자 하는 내부표정요소 개수에 의한 측량 정확도 등을 분석하여 효율적인 조합을 도출하고자 하였다. 마지막으로, 도출된 조합을 기반으로 한 현장 셀프캘리브레이션에 의한 측량 결과를 실험실 셀프 캘리브레이션 결과와의 측량 정확도와 비교했을 때 반 픽셀의 이내의 차이를 보여 동일한 정확성을 달성할 수 있음을 확인할 수 있었고, 지반변형과 같은 응용분야의 정밀 측정에 충분히 활용 가능함을 알 수 있었다.

• 한국생산제조학회지
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• 제22권3호
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• pp.408-413
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• 2013

Micro-features such as grooves and lenses, which perform optical functions in flat displays, should be manufactured with a good form accuracy because this is directly related to their optical performance. As the size of the display increases, it is very difficult to maintain a high relative accuracy because of the inherent geometric errors such as the waviness of a large-area plate. In this paper, the optical effect of these geometric errors is investigated, and surface-referenced micro-grooving to measure and compensate for such geometric errors on line is proposed to improve the form accuracy of the micro-grooves. A PZT-based fast depth adjustment servo system is implemented in the tool holder to maintain a uniform groove depth in reference to the wavy surface. Through experiments, the proposed method is shown to be an efficient way to produce high-quality micro- grooves on a wavy die surface.

• 제어로봇시스템학회논문지
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• 제8권7호
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• pp.573-577
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• 2002

A tape feeder of a SMD(Surface Mount Device) mounter is a device that sequentially feeds electronic components on a tape reel to the pick-up system of the mounter. As components are getting much smaller, feeding accuracy of a feeder becomes one of the most important factors for successful component pick-up. Therefore, it is critical to keep the feeding accuracy to a specified level in the assembly and production of tape feeders. This paper describes a tape feeder inspection system that was developed to automatically measure and inspect feeding accuracy using machine vision. It consists of a feeder base, an image acquisition system, and a personal computer. The image acquisition system is composed of CCD cameras with lens, LED illumination systems, and a frame grabber inside the PC. This system loads up to six feeders at a time and inspects them automatically and sequentially. The inspection software was implemented using Visual C++on Windows NT with easily usable GUI. Using this system, we can automatically measure and inspect the quality of all feeders in production process by analyzing the measurement results statistically.

• 한국정밀공학회지
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• 제19권12호
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• pp.163-170
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• 2002

The quality of a precision product, in general, relies on the accuracy and precision of its manufacturing and inspection process. In many cases, the level of precision in the manufacturing and inspection system is also dependent on the positioning capability of tool with respect to the work piece in the process. Recently the positioning accuracy level has reached to the level of submicron and long range of motion is required. For example, for 1 GDARM lithography, 20nm accuracy and 300mm stroke needs. This paper refers to the lithography stage especially to fine stage. In this study, for long stroke and high accuracy, the dual servo system is proposed. For the coarse actuator, LDM (Linear DC Motor) is used and for fine one VCM is used. In this study, we propose the new structure of VCM for the fine actuator. It is 3 axis precision positioning stage for an aligner system. After we perform the optimal design of the stage to obtain the maximum force, which is related to the acceleration of the stage to accomplish throughput of product. And we controlled this fine stage with TDC. So we obtained 50nm resolution. So later more works will be done to obtain better accuracy.

• 대한간호학회지
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• 제37권1호
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• pp.125-134
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• 2007

Purpose: The study aimed to identify the effects of a newborn care education program on newborn care confidence and behavioral accuracy of primiparas in a postpartum care center. Method: This was a quasi-experimental study with a non-equivalent control group non-synchronized design. Subjects were 29 primiparas selected from a postpartum care center in D and P hospitals in Ulsan. The intervention was a newborn care education program which was composed of education with a booklet, demonstration, watching a video, and verbal encouragement. The outcome variables were newborn care confidence and behavioral accuracy. Data was collected from Feb. 1 to Mar 22 in 2005 with self-administered questionnaires and observation by researchers. Data was analyzed using the $X^2-test$, Fisher's exact test, t-test and ANCOVA. Result: The experimental group showed significantly higher score changes between the pre-test and post-test in confidence and behavioral accuracy than the control group. Conclusion: The newborn care education program showed positive effects on newborn care confidence and behavioral accuracy of primiparas in a postpartum care center. Therefore, we recommend that this program should be applied in postpartum care centers.

• 한국공작기계학회논문집
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• 제17권2호
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• pp.90-96
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• 2008

A pneumatic system was proposed to evaluate displacement accuracy of the pneumatic actuator without external load and to analyze capability of integration of the proposed valve system. The proposed pneumatic system consisted of a combination of pneumatic valves, two proximity sensors, and a programmable logic controller(PLC). The position controller is based on the PLC controller connected with the proximity sensors. Displacement accuracy of the pneumatic cylinder stroke was tested by varying air pressures of the supply and discharge-side and strokes of the pneumatic cylinder. The displacement accuracy of the pneumatic cylinder stroke increased as the supply and discharge side of air pressure increased at the stroke length of 133mm. Also the displacement accuracy increased as the stroke length increased with a fixed supply and discharge side of air pressure of the pneumatic cylinder as 3.5 and $4.5kg/cm^2$, respectively. The most accurate displacement of the pneumatic cylinder(i.e., standard deviation of 0.01 mm) was obtained at the supply and discharge side of air pressure of 4.0 and $5.0kg/cm^2$, respectively, and strokes of 170 and 190 mm among arbitrarily selected supply and discharge side air pressures and strokes.

• 제어로봇시스템학회논문지
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• 제18권8호
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• pp.713-718
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• 2012

Lumber spine range of motion has been used to measure of physical and functional impairment by various tools from a ruler to 3D kinematic devices. However, pre-existing tools have problems in either movement or accuracy and reliability limitations. Accurate devices are limited by fixed space whereas simple devices are limited in measuring complex movements with less accuracy. In order to solve the location, movement and accuracy limitations at once, we have developed a novice measurement device equipped with accelerometer sensor and gyroscope sensor for getting three-dimensional information of motion. Furthermore, Kalman filter was applied to the algorithm to improve accuracy. In addition, RF wireless communication was added for the user to conveniently check measured data in real time. Finally, the measurement method was improved by considering the movement by a reference point. An experiment was conducted to test the accuracy and reliability of the device by conducting a test-retest reliability test. Further modification will be conducted to used the device in various joints range of motion in clinical settings in the future.

• 한국전산구조공학회논문집
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• 제29권2호
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• pp.123-130
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• 2016

선박 건조 시장의 요구를 맞추기 위하여 신속한 건조의 목표로 노력하고 있는 조선소가 선박 정도관리에 대한 요구가 갈수록 높아지고 있다. 선박 건조 공정에서 생산성의 향상과 생산 주기의 단축을 위하여 선박 부재의 정도평가를 전 주기에서 수행해야 하는 것은 중요하다. 선박의 품질을 높이기 위하여 조선소에서 블록의 정도제어를 수행하는 것은 선박의 건조 주기를 단축할 수 있을 뿐만 아니라 건조 비용도 줄일 수 있다. 선박 블록의 정도를 제어하는 중심은 선박 블록 통합 정도관리 시스템을 만들어야 한다. 이 시스템은 "Non-allowance Shipbuilding"의 목표로 정도관리의 총괄성, 블록 정도의 향상, 정도 관리 과정의 표준화 등이 이루어져야 한다. 일반적으로 정도관리를 수행하는 관리자가 광파측정기를 이용하여 선박 블록의 접합면에 있는 주요 포인트(vital point)를 측정하고 수집하지만 무거운 계측장비를 가지고 블록의 정도관리를 수행하는 것은 불편할 뿐만 아니라 시간도 오래 걸린다. 본 논문에서는 선박 블록의 정도관리 시간을 단축할 수 있는 포인트 클라우드 기반으로 3차원 레이저 스캐너를 이용한 선박 블록 탑재 전에 오차예측 방법을 제안하였다. 이 방법은 ICP(iterative closest point) 알고리즘으로 측정된 포인트 클라우드와 설계된 점들의 비교 작업을 수행한 다음에 허용범위 내의 오차를 만족하는 지를 판단한다.

• Spatial Information Research
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• 제16권4호
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• pp.401-410
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• 2008

본 연구에서는 우리나라의 측지기준점의 개선에 대하여 소개하였다. 개선의 내용은 기준점의 구조와 정확도에 중점을 두어 설명하였으며, 구조의 경우 3차원 기준점으로 변화하면서 정확도, 포함 정보, 그리고 기준점의 위계에 대하여 서술하였다. 정확도의 개선은 위성측지 기술의 발달과 정밀지오이드를 기반을 주 내용으로 하고 있으며, 기준점의 개념은 위치뿐 만 아니라 중력, 환경정보와 같은 다양한 공간정보를 포함하여 전반적인 정보의 분석이 가능한 점이 강조되었다. 또한 RFID와 CDMA 기술을 이용한 공간정보의 효율성과 신속성을 소개하였다. 이러한 모든 노력으로 한국의 측지망은 보다 정확하고 다양한 공간정보를 효율적으로 전달할 수 있을 것이라 판단되며 이러한 개선이 측지 기준점의 역할과 미래의 방향에 큰 영향을 미칠 것으로 기대된다.