• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.11
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• pp.1012-1019
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• 2000

A proficiency test is one of programs which Korea Research Institute of Standards and Science(KRISS), as national metrology institute, is putting in operation for the mutual recognition arrangement. The Fluid Flow Group of KRISS evaluated the measurement capability for liquid flowmeter calibrator of the national calibration and test organizations. The uncertainty of national standard system was estimated in accordance with Guide to The Expression of Uncertainty in Measurement (ISO), and the turbine flowmeter, which was used for the round-robin test as a reference flowmeter, was characterized. The round-robin tests with the turbine flowmeter package were carried out in 1995 and 1999. The test results of the organizations and those of KRISS agreed within $\pm0.2$%. It is found thus that the organizations have the traceability of the national standard for liquid flow measurement.

• Journal of Sensor Science and Technology
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• v.4 no.1
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• pp.43-50
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• 1995

We measured the traceability error for nine high temperature calibration service centers including KRISS through the round-robin test. In this test the type S thermocouple, which used as a calibration standard thermometer commonly, was accommodated as a test thermocouple. Intercomparison data of three institutions were coincident with KRISS's data within ${\pm}0.5^{\circ}C$, which was the calibration uncertainty of the type S thermocouple, but the remaining six institution's data were deviated from the assigned uncertainty level. Deviation of the intercomparison data increased gradually according to the increase of the test temperature. and the maximum difference was so large as about $2.0^{\circ}C$ at the highest test temperature, gold point. In this study we found the traceability error of high temperature calibration service center for a high temperature standard was within $2.0^{\circ}C$.

• Proceedings of the Korean Information Science Society Conference
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• 2002.04a
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• pp.496-498
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• 2002

이동 에이전트는 네트워크 내에서 스스로 이동하면서 사용자 또는 다른 개체 대신 행동할 수 있는 컴퓨터 프로그램을 말하며 이동 에이전트가 적용될 수 있는 응용 분야로는 전자 상거래, 정보 검색, 병렬 처리, 네트워크 관리 등이 있다. 이러한 응용 분야에서 이동 에이전트가 작업을 수행하기 위해 이동할 때 작업 시간을 고려한 후 적절한 방법으로 목표 노드를 선택한다면 전체적인 작업 처리 시간은 단축되어 시스템의 성능은 향상될 것이다. 본 논문에서는 이동 에이전트의 목표 노드 선택 방법을 정적인 노드 선택법, 동적인 노드 선택법, 단순 순회 법으로 구분하고 이동 에이전트의 작업 시간에 따라 세 가지 방법을 적용하여 수행 성능을 측정하고 결과를 통해서 이동 에이전트의 작업 시간에 따라 적절한 노드 선택법을 사용할 때 전체적인 성능이 향상되는 것을 알 수 있었다.

• Journal of the Korean Society for Heat Treatment
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• v.14 no.5
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• pp.275-281
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• 2001

To improve the reliability of hardness test results, Rockwell hardness round robin test was carried out for 10 laboratories. The test condition was the same with the ISO(International Standards Organization) standards. Korea Research Institute of Standards and Science(KRISS) supplied the hardness standard blocks and an indenter to laboratories for the measurement. The participating laboratories measured hardness of the specified areas on the blocks for 6 times with their own indenter as well as common indenter, respectively, and reported the results to KRISS. The result showed that quite large amount of the differences came from the indenter and it is necessary to change indenter with better quality for improved reliability in hardness measurement.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.32 no.9
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• pp.712-719
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• 2008

Light Oil Flow Standard System(LOFSS), as a national oil flow standard system, in Korea Research Institute of Standards and Science(KRISS) was developed for oil flowmeter calibration, and the expanded uncertainty of flow quantity determination was estimated within 0.04 %. In order to improve the reliability of the LOFSS measurement, a proficiency test was carried out in the flow range of 20 and $240\;m^3/h$ (Reynolds number $20,000{\sim}900,000$). A turbine flowmeter was used as a transfer package in round robin test. The water flow standard system of KRISS, the pipe prover of the national calibration and test organization and the master meter calibrator of the turbine flowmeter supplier, which used the different working fluid respectively, were compared with the turbine flowmeter measurement. The maximum difference of measurement was 0.15 % between the LOFSS and the pipe prover. The En numbers of the each system measurement were evaluated at the same Reynolds number. It was found that the En numbers were less than 1 in the comparison, which means the procedures of the uncertainty estimation of the each calibrators were reasonable and reliable.

• The KIPS Transactions:PartD
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• v.12D no.2 s.98
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• pp.259-266
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• 2005

Recently data centric routing or application dependent routing protocols are emerged in mobile ad hoc networks. In this paper, we propose a routing method for query processing in MANET(Mobile Ad hoc NETwork) environment, called road-based query routing, with consideration on real time traffic information of large number of vehicles. In particular, we focus on the method that process arrival time dependent shortest path query in MANET without a central server on the road networks. The main idea of our approach lies in a routing message that includes query predicates based on the road connectivity and on data gathering method in real time from vehicles on the road by ad-hoc network. We unify route discovery phase and data delivery(query processing) phase in our mechanism and reduce unnecessary flooding messages by pruning mobile nodes which are not on the same or neighboring road segments. In order to evaluate the performances of the proposed method, we established a model of road networks and mobile nodes which travel along the roads. The measurement factor is the number of nodes to whom route request is propagated according to each pruning strategy. Simulation result shows that road information is a dominant factor to reduce the number of messages.

• The Journal of the Convergence on Culture Technology
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• v.10 no.3
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• pp.845-849
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• 2024

Currently, rail surface defects are increasing due to the aging of urban railway rails, but in the detailed guidelines for track performance evaluation established by the country, rail surface damage is inspected with the naked eye of an engineer and with simple measuring tools. It is very important to discover defects in the rail surface through periodic track tours and visual inspection. However, evaluating the severity of defects on the rail surface based on the subjective judgment of the inspector has significant limitations in predicting damage inside the rail. In this study, the characteristics of cracks inside the rail due to rail surface damage were studied. In field measurements, rail surface damage was selected, old rail samples were collected in the acceleration and braking sections, and a scanning electron microscope (SEM) was used to evaluate the rail surface damage was used to analyze the crack characteristics. As a result of the analysis, the crack mechanism caused by the running train and the crack characteristics of the acceleration section where cracks occur at an angle rising toward the rail surface were experimentally proven.

• Journal of the Korean Society for Nondestructive Testing
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• v.19 no.4
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• pp.300-313
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• 1999

비파괴검사 기술의 레벨 향상과 안정화를 통한 시간적 재현성이 있는 비파괴검사 결과의 확보를 위해서는 비파괴검사 기술자의 자격 인정 및 인증(nondestructive testing qualification and certification of personnel)제도의 확립이 매우 중요하다. 비파괴검사 결과에 대한 유효성은 비파괴검사을 실시하는 사람의 능력이나 비파괴검사에 대한 책임을 지고 있는 사람의 능력에 크게 의존한다. 1974년부터 원자력 선진국들이 중심이 되어 수행된 PISC 프로그램(program for inspection of steel components) 및 EPRI 등에서는 순회시험 (piping inspection round-robin: PIRR trial) 결과 기존 비파괴검사 방법은 모의 시험편에 있는 상당히 큰 결함도 탐지하지 못하거나 정확한 결함크기를 측정하는데 실패한 경우가 있으며, 검사자의 기량 또는 신체조건에 상당한 차이가 있는 것으로 나타났다[1]. 국제표준화기구(ISO)의 비파괴검사 기술자의 기량인정 및 인증에 대한 국제규격안 DIS(draft international standard) 9712에서는 비파괴검사를 기획 실시 감독 감시 평가를 하기 위한 적절한 이론적 및 실무적 지식을 필요로 하는 기술자의 능력을 평가하고, 문서화하는 방법을 제공하는 절차를 제시하고 있다. 국제표준화기구에 의한 비파괴검사 기술자의 기량인정 및 인증에 대한 국제통합을 추진하는 동기는 제 3자에 의한 체계적인 인증시스템을 가지고 있지 않은 나라와 새로운 NDT 방법에 대해서 인증제도를 적용할 때 세계적인 공통성을 갖도록 유도하기 위함이다. 현재, 우리나라 비파괴검사 기술자의 기술자격 인증제도는 국가기술자격법에 의거하여 한국산업인력공단에서 주관하여 기술사, 기사, 산업기사, 기능사로 구분하여 실시하고 있다. 국제표준화기구의 비파괴검사 기술자의 자격과 인증에 대한 국제 통합화(안)[2]이 거의 마무리 단계에 있고 일본을 비롯한 많은 나라가 국제규격을 기초로 한 새로운 인증제도를 발족시켜 거의 시행 단계에 있다. 반면 국내에서는 한국비파괴검사학회(KSNT)에서 비파괴검사 기술자의 자격인정 및 인증제도의 개선방향이 제시된 바 있고 [3], 표준화위원회에서 나름대로 준비를 하고 있으나 아직 구체적인 실천단계에와 있지 못하다. 본 고에서는 최근 대폭수정 보완된 ISO/DIS 9712 국제규격(안)을 회원들에게 소개하고, 우리나라의 향후 대응방안에 관한 회원 여러분의 의견 수렴에 도움을 주고자 ISO/DIS 9712(1997)를 번역하여 제공한다.

• The Journal of the Convergence on Culture Technology
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• v.10 no.1
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• pp.585-590
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• 2024

In this study, rail surface defects are increasing due to the aging of urban railway rails, but in the detailed guidelines for track performance evaluation established by the country, rail surface damage is inspected with the naked eye of engineers and simple measuring tools. With the recent enactment of the Track Diagnosis Act, a large budget has been invested and the volume of rail diagnosis is rapidly increasing, but it is difficult to secure the reliability of diagnosis results using labor-intensive visual inspection techniques. It is very important to discover defects in the rail surface through periodic track tours and visual inspection. However, evaluating the severity of defects on the rail surface based on the subjective judgment of the inspector has significant limitations in predicting damage inside the rail. In this study, the rail internal crack characteristics due to rail surface damage were studied. In field measurements, rail surface damage locations were selected, samples of various damage types were collected, and the rail surface damage status was evaluated. In indoor testing, we intend to analyze the correlation between rail surface defects and internal defects using a electron scanning microscope (SEM). To determine the crack growth rate of urban railway rails currently in use, the Gaussian probability density function was applied and analyzed.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.48 no.2
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• pp.16-27
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• 2011

Embryo is a very early stage of the development of multicellular organism such as animals and plants. It is an important research target for studying ontogeny because the fundamental body system of multicellular organism is determined during an embryo state. Researchers in the developmental biology have a large volume of embryo image databases for studying embryos and they frequently search for an embryo image efficiently from those databases. Thus, it is crucial to organize databases for their efficient search. Hierarchical clustering methods have been widely used for database organization. However, most of previous algorithms tend to produce a highly skewed tree as a result of clustering because they do not simultaneously consider both the size of a cluster and the number of objects within the cluster. The skewed tree requires much time to be traversed in users' search process. In this paper, we propose a method that effectively organizes a large volume of embryo image data in a balanced tree structure. We first represent embryo image data as a similarity-based graph. Next, we identify clusters by performing a graph partitioning algorithm repeatedly. We check constantly the size of a cluster and the number of objects, and partition clusters whose size is too large or whose number of objects is too high, which prevents clusters from growing too large or having too many objects. We show the superiority of the proposed method by extensive experiments. Moreover, we implement the visualization tool to help users quickly and easily navigate the embryo image database.