• 동력기계공학회지
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• 제14권1호
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• pp.40-46
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• 2010

This paper shows the development process for measuring three-dimensional flow velocity components in a web-browser. The system is developed in an embeddable C/C++ interpreter Ch and Ch-CGI toolkit. The interface for the web-based measurement system consists of a set of web HTML files and Ch files for CGI. All of data in web browser are passed to Ch-CGI script to generate the output of new HTML file. PC-Server and PC-Client can submit measurement parameters and receive the text/graphical results each other. PC-Client can control the test equipment by using a parameters that received from PC-Server. It also can pass the test results between the web-based measurement system. In summary, the designed measurement system is evaluated, the outputs shown well on the web browser.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.391-395
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• 2002

This paper described about the ultra-precision profile measurement of aspheric surfaces using contact probing technique. A contact probe has been designed as a sensing device to obtain measuring resolutions in nanometer regime utilizing a leaf spring mechanism and a capacitive-type sensor. The contact probe is attached on the z-axis during measurement while aspheric objects are supported on the single point diamond turning machine(SPDTM). The machine xz-axis motions are monitored by a set of two orthogonal plane mirror type laser interferometers. Experimental results show that the contact probing technique developed of On-machine Measurement System in this investigation is capable of providing a repeatability of 20 nanometers with a $\pm$20 uncertainty of 300 nanometers.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2003년도 유체기계 연구개발 발표회 논문집
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• pp.107-114
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• 2003

The influence of property difference in refraction index on micro PIV measurement of two-fluid flow in a microchannel was analyzed. The difference of measurement planes in two fluids would bring misunderstanding of the physics. The objective-imaging system for two-fluid flow measurement was presented, and the condition for measurement of valid velocity profile across two-fluid interface was derived. A micro PIV experimental system was set up to measure two-fluid flow inside a Y-shape microchannel. Under the conditions, three cases of two-fluid flow of glycerol solutions at different concentration (${\phi}$), e.g., (${\phi}=0\;and\;{\phi}=0.2,\;{\phi}=0.1\;and\;{\phi}=0.5,\;{\phi}=0\;and\;{\phi}=0.6$, were measured. Close agreement of experimental and numerical results was found.

• Wind and Structures
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• 제16권2호
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• pp.137-156
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• 2013

A wind tunnel test of a scaled-down model and field measurement were effective methods for elucidating the aerodynamic behavior of a chimney under a wind load. Therefore, the relationship between the results of the wind tunnel test and the field measurement had to be determined. Accordingly, the set-up and testing method in the wind tunnel had to be modified from the field measurement to simulate the real behavior of a chimney under the wind flow with a larger Reynolds number. It enabled the results of the wind tunnel tests to be correlated with the field measurement. The model surface roughness and different turbulence intensity flows were added to the test. The simulated results of the wind tunnel test agreed with the full-scale measurements in the mean surface pressure distribution behavior.

• 정보처리학회논문지:컴퓨터 및 통신 시스템
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• 제4권1호
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• pp.15-22
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• 2015

멀티셋에서 중복을 제외한 서로 다른 원소의 수를 추정하는 것은 네트워크 트래픽 측정 분야에서 매우 잘 알려진 문제이며, 많은 알고리즘들이 제안되었다. 최근에는 선형 카운팅 기법(Linear Counting)에 기반해서 매우 작은 메모리만을 이용해서 멀티셋의 크기를 추정하는 알고리즘이 개발되었다. 너무 많은 데이터를 처리하기 어려운 경우 전체 데이터를 처리하지 않고, 패킷의 일부를 샘플링해서 사용하는데, 이 샘플링은 일반적으로 정확도에 부정적인 영향을 주는 것으로 알려져있다. 하지만, 이 논문에서는 멀티셋의 크기를 추정하는데 있어서 CSE를 이용하는 경우 샘플링이 정확도와 측정 범위의 측면에서 오히려 전수조사를 하는 MCSE보다 더 좋은 결과를 낼 수 있음을 보였다. 이를 입증하기 위해 수학적 분석, 실제 데이터를 이용한 실험을 수행하고, CSE, MCSE 그리고 CSES를 비교하였다.

• 한국기계가공학회지
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• 제14권2호
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• pp.51-58
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• 2015

In this study, we developed an automated non-contact thickness measurement machine that continuously and precisely measures the thickness and warp of a PCB product using a laser sensor. The system contains a measurement part to measure the thickness in real time automatically according to the set conditions with an alignment supply unit and unloading unit to separate OK and NG products. The measurement machine was utilized to evaluate the performance at each step to minimize measurement error. At the zero setting for the initial setup, the standard deviation of the 216 samples was determined to be $5.52{\mu}m$. A measurement error of 0.5mm and 1.0mm as a standard sample in the measurement accuracy assessment was found to be 2.48% and 2.28%, respectively. In the factory acceptance test, the standard deviation of 1.461mm PCB was measured as $28.99{\mu}m$, with a $C_{pk}$ of 1.2. The automatic thickness measurement machine developed in this study can contribute to productivity and quality improvement in the mass production process.

• Journal of Electrical Engineering and Technology
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• 제10권2호
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• pp.474-486
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• 2015

This paper proposes a multi-objective optimal placement method of Phasor Measurement Units (PMUs) in large electric transmission systems. It is proposed for minimizing the number of PMUs for complete system observability and maximizing measurement redundancy of the buses, simultaneously. The measurement redundancy of the bus indicates that number of times a bus is able to monitor more than once by PMUs set. A high level of measurement redundancy can maximize the system observability and it is required for a reliable power system state estimation. Therefore, simultaneous optimizations of the two conflicting objectives are performed using a binary coded firefly algorithm. The complete observability of the power system is first prepared and then, single line loss contingency condition is added to the main model. The practical measurement limitation of PMUs is also considered. The efficiency of the proposed method is validated on IEEE 14, 30, 57 and 118 bus test systems and a real and large- scale Polish 2383 bus system. The valuable approach of firefly algorithm is demonstrated in finding the optimal number of PMUs and their locations by comparing its performance with earlier works.

• 과학교육연구지
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• 제41권3호
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• pp.480-498
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• 2017

본 연구는 측정 영역의 문제해결 과정에서 나타나는 초등학교 6학년 학생의 오류를 분석하였다. 초등 5~6학년군의 내용에서 학생들이 어려워하는 부분에 대한 오류를 분석함으로써 학생들의 성취기준 도달을 도울 수 있는 교수 학습에서의 시사점을 도출하고자 하였다. 첫째, 문제를 해결할 수 있는 충분한 시간을 학생들에게 제공했음에도 불구하고 풀이과정을 바르게 쓰지 못한 학생이 문항에 따라 약 30~60%에 이르렀다는 점은 학생들이 측정 영역의 일부에서 어려움을 겪고 있음을 시사한다. 둘째, 단위 사이의 관계에 대한 불충분한 이해 등 측정 단위에 대한 학생들의 이해가 낮은 것을 확인하였다. 셋째, 학생들은 삼각형에서 밑변이 정해지면 그에 따라 높이가 결정되고 이로부터 삼각형의 넓이를 구하는 여러 개의 식을 도출할 수 있다는 것에 대한 이해가 낮은 것으로 나타났다.

• 한국산학기술학회논문지
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• 제19권2호
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• pp.86-89
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• 2018

본 논문은 일상 생활스포츠의 일환으로 누구라도 쉽고 편하게 단거리 육상기록 측정을 할 수 있는 4레인 무선 구간기록 측정 시스템에 적용된 기술을 소개한다. 무선 육상경기 기록측정 시스템은 출발점의 스타트 버튼과 음성안내 스피커, 주자의 도착을 탐지하는 발판 스위치, 시작점과 도착점간의 지그비 통신, 구간기록을 계산하고 그 결과를 디스플레이하는 컨트롤보드 및 전광판 등으로 구성된다. 구간기록은 시작점의 스피커를 통한 레디-셋-고(총성) 음성 안내방송 시점과 결승점 발판 스위치의 주자 도착 탐지 시간의 차로 계산되며, 출발선의 지그비 통신노드는 시작스위치 탐지 시각을 자신의 내부시간을 기준으로 무선을 통하여 도착점의 통신노드로 전송하기 때문에 출발과 도착 통신노드간의 시간동기화가 구간기록 측정의 정밀도를 좌우한다. 이 논문에서 소개한 무선 구간 기록 측정 시스템은 10ms의 시간정밀도를 목표로 하고 있으며, 기존 전문 상용화시스템의 1ms의 시간정밀도와 다르게 일상 생활스포츠용으로 개발하여 비용이 상당히 저렴하며 기존의 수동 측정 방식을 사용한 경우보다 더 간편하게 기록 정보를 획득할 수 있다는 장점이 있다.

• 수산해양기술연구
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• 제22권1호
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• pp.41-48
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• 1986

Ifis recommended that the injection rate should be accurate and reliable in the input data of the performance simulation in diesel engine. Matsuoka Sin improved W. Bosch's injection ratio measurement system. Matsuoka Sin reduced length of the test pipe and set the orifice. However, it was not measured accurately to measure the injection ratio due to reflection wave. In the present thesis, the improved measurement system with combination of the conventional W. Bosch type injection ratio measurement system and Matsuoka Sin type corrected W. Bosch type was practically made. The location of orifice and throttle valve was modified and set one more back pressure valve in order to reduce the effect of reflection wave. The results according to injection condition of multi-hole nozzle are following: 1. Measurement error of injection ratio measurement system in this thesis was $\pm$ 1 %, therefore, its reliability was good. 2. The form of injetion ratio is changed from trapezoidal shape to triangle shape with increase of revolution per minute when injection amount is constant. 3. In the case of constant rpm, the initial injection ratio is almost constant regardless of the amount, meanwhile the injection period becomes longer with increase of the amount. 4. The injection pressure of nozzle isn't largely influenced with injection ratio in the case of constant injection amount and rpm, otherwise the initial injection amount is increased by 3-4% when the injection pressure is low. 5. The injection ratio isn't nearly influenced with back pressure.