• 대한간호학회지
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• 제36권8호
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• pp.1295-1300
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• 2006

Purpose. The purposes of this methodologic paper are to (1) describe theoretical background in conducting research across different cultures; (2) address measurement issues related to instrument administration; and (3) provide strategies to deal with measurement issues. Methods. A thorough review of the literature was conducted. A theoretical background is provided, and examples of administering instrument in studies are described. Results. When applying an instrument to different cultures, both equivalence and bias need to be established. Three levels of equivalence, i.e., construct equivalence, measurement unit equivalence, and full score comparability, need to be explained to maintain the same concept being measured. In this paper, sources of bias in construct, method, and item are discussed. Issues related to instrument administration in a cross-cultural study are described. Conclusion. Researchers need to acknowledge various group differences in concept and/or language that include a specific set of symbols and norms. There is a need to question the philosophical and conceptual appropriateness of an assessment measure that has been conceptualized and operationalized in a different culture. Additionally, testing different response formats such as narrowing response range can be considered to reduce bias.

• 한국분무공학회지
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• 제27권2호
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• pp.84-93
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• 2022

To implement carbon-neutrality in transportation sectors until 2050, hydrogen is considered a promising fuel for internal combustion engines because hydrogen does not contain carbon itself. Although hydrogen does not emit CO₂ emission from its combustion process, the low energy density in a volume unit hinders the adoption of hydrogen. Therefore, the understanding of hydrogen jet behavior and measurement of equivalence ratio must be conducted to completely implement the high-pressure hydrogen direct injection. The main objective of this research is feasibility test of hydrogen local equivalence ratio measurement by laser-induced breakdown spectroscopy (LIBs). To visualize the macroscopic structure of hydrogen jet, high-speed schlieren imaging was conducted. Moreover, LIBs has been adopted to validate the feasibility of hydrogen local equivalence ratio measurement. The hydrogen injection pressure was varied from 4 MPa to 8 MPa and injected in a constant volume chamber where the ambient pressure was 0.5 MPa. The increased injection pressure extends the vertical penetration of hydrogen jet. Due to the higher momentum supply when the injection pressure is high, the hydrogen has easily diffused in all directions. As the laser trigger timing has delayed, the low hydrogen atomic emission was detected due to the longer mixture formation time. Based on equivalence ratio measurement results, LIBs could be applied as a methodology for hydrogen local equivalence ratio measurement.

• 대한기계학회논문집
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• 제18권4호
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• pp.1064-1071
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• 1994

There are three active radicals which become to the scale of flame diagnostics at the flame front. They are OH, CH and $C_2$ radical. For this, optical measurement system which could monitor simultaneously the luminous waves of three radicals, was constructed. These were analyzed statistically into the cross correlation, coherence and phase. Through such an statistical treatment, combustion characteristics was investigated at the primary zone of gas turbine combustor. The local equivalence ratio was predicted with the ratio of luminuous intensity between CH and $C_2$ radical. This result was matched up to the equivalence ratio calculated from gas composition within 5% error. In general, equivalence ratio was said to be 1.0 at flame front, but it could be increased up to about 1.2 depending on the degree of swirl intensity in case of changing properly the air amount of primary zone.

• 한국정밀공학회지
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• 제11권2호
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• pp.95-103
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• 1994

The purpose of this paper is to provide the experimenters who use the oblique incidence ultrasonic method for anisotropic elastic constants measurement eith some useful relations. In particular, the equivalence of the times of flight by the energy ad phase velocities, which is key to the oblique incidence method, is proved explicitly. This equivalence greatly simplifies the analysis of immersion measurement results. In oredr to correctly measure the transit time of an immersed sample using the oblique incidence, the receiving transducer should be shifted laterally, and an expression in given for this shift. A method for determining all nine elastic constants of an orthotropic material is briefly described and the measurement results are listed for SiC particulate reinforced A1 matrix composites.

• 한국수학교육학회지시리즈A:수학교육
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• 제57권2호
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• pp.179-196
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• 2018

The purpose of this study was to investigate the measurement equivalence and to suggest application ways in teaching aptitude and personality test results for pre-service mathematics teachers between a graduate school of education and a college of education. This study analyzed the scores of the teaching aptitude and personality test of 36 pre-service mathematics teachers enrolled in a graduate school of education and 111 pre-service mathematics teachers in a college of education by performing a multivariate generalizability analysis. The main results were as follows. First, graduate's pre-service mathematics teachers had a higher level of teaching aptitude and personality than that of college's pre-service mathematics teachers based on the total scores. In addition, graduate's pre-service mathematics teachers had higher levels of teaching aptitude and personality than those of college's pre-service mathematics teachers except for a creativity application domain based on the sub-domain scores. Second, cognitive domains were measured more precisely but affective domains were measured less precisely for graduate's pre-service mathematics teachers than for college's pre-service mathematics teachers. Third, regardless of school levels, Cronbach's ${\alpha}$ values, which might be overestimated by applying the classical test theory, were higher than dependability coefficients. Fourth, this study showed a somewhat negative result in ensuring the measurement equivalence for a problem solving exploration domain. However, regardless of school levels, this study indicated that the overall measurement was generally reliable on composite scores. Based on these results, it was confirmed that multivariate generalizability methodologies' approach can be useful for exploring the measurement equivalence issues. Finally, this study suggests how to utilize the results of the test, how to apply a multivariate generalizability analysis for detecting the measurement equivalence, and how to develop future research based on limitations.

• 대한기계학회논문집 C: 기술과 교육
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• 제5권2호
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• pp.105-113
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• 2017

한국인정기구(KOLAS)는 아시아태평양인정협의체(APLAC)에 소속되어 있으며, 측정 결과를 SI 단위로 소급하고 이를 유지시키기 위해 교정기관 인정제도를 운영하고 있다. 2016 년 6 월 현재, 22 개의 기관이 KOLAS 물유량 분야 교정기관으로 지정되어 있다. 이 중 12 개 KOLAS 교정기관들이 한국계량측정협회(KASTO)가 2015 년에 주관한 물유량 숙련도 시험(PM2015-08)에 참가했다. 이번 숙련도 시험은 KOLAS 교정기관들의 교정측정능력(CMC)을 고려하여 3 가지의 유량 범위($3.6m^3/h{\sim}12m^3/h$, $40m^3/h{\sim}80m^3/h$, $40m3/h{\sim}200m^3/h$)에서 실시되었다. 숙련도 시험의 목적은 참가기관들의 CMC 가 기준시험소(KRISS)의 CMC 와 비교하여 측정동등성이 성립하는지 여부를 판단하기 위한 것이다. 측정동등성은 측정동등성지수(number of equivalence; $E_n$)를 산출하여 평가했다. ${\mid}E_n{\mid}$ < 1 일 때, 측정동등성이 확립된다고 판단했다. 이번 시험에서 12 개 KOLAS 교정기관 모두 기준시험소와 측정동등성이 성립함을 확인했다.

• 한국분무공학회지
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• 제3권4호
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• pp.35-42
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• 1998

Laser Raman scattering method has been applied to measure equivalence ratio of methane/air and propane/air mixture in constant volume combustion chamber. We used high power KrF excimer laser$(\lambda=248nm)$ and a high gain ICCD camera to capture low intensity Raman signal. Raman shifts and Ram cross-sections of $H_2,\;O_2,\;N_2,\;CO_2,\;CH_4\;and\;C_3H_8$ were measured precisely. Our results showed an excellent agreement with other groups. Mole fraction measurement of $O_2\;and\;N_2$ from air showed that $O_2\;:\;N_2$ = 0.206 : 0.794. We used constant volume combustion chamber and gas injector which is operated at $5\sim10barg$. Methane and propane are used as a fuel. 50 Raman signal are obtained and ensemble averaged for measurement of equivalence ratio. Our measured results showed that the equivalence ratio of fuel/air mixture is reasonable at ${\pm}5%$ error range.

• 센서학회지
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• 제32권6호
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• pp.447-454
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• 2023

The Korea Laboratory Accreditation Scheme (KOLAS) operates accreditation programs for ensuring measurement traceability with the International System (SI) of Units - the highest calibration standard that measurements can be tested against. As of September 2023, there are 70 KOLAS-accredited laboratories in the Republic of Korea that specialize in humidity calibration. Among them, 32 KOLAS laboratories, along with one laboratory not affiliated with KOLAS, participated in the proficiency test (PM 2023-11) for relative humidity transducers in 2023. This proficiency test was conducted within a relative humidity range of 20-90% at a temperature of approximately 20 ℃, taking into consideration the calibration and measurement capability (CMC) of the participating laboratories. The primary objective of the proficiency test was to establish the measurement equivalence between each participating laboratory and the reference laboratory, by calculating the number of equivalence (En). When |En| was less than 1, the measurements from the participating and reference laboratory were equivalent. Out of the 33 participating laboratories, 32 successfully met this criterion and passed the proficiency test.

• 한국연소학회지
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• 제10권1호
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• pp.7-12
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• 2005

The surface flames in perforated ceramic burner are experimentally characterized to investigate the effects of equivalence ratio and heating rate. The results show that the surface flames are classified into green, red radiant and blue surface flame as the decrease of equivalence ratio. Each flame is maintained very stable at the specified equivalence ratio and represents the same flame characteristics at any orientation of ceramic burner. Particularly the blue surface flame is found to be very stable at very lean equivalence ratio at 7000kcal/hr to 20000kcal/hr heating rates. And the exhausted NOx measurement shows that blue surface flame represents the lowest NOx emission regardless of the location of burner since it sustains very stable at lean mixture ratio.

• 대한기계학회논문집B
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• 제25권10호
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• pp.1311-1317
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• 2001

To investigate only the effects of the stratified mixture distribution on initial flame propagation and combustion characteristics, the instantaneous equivalence ratio in the spark plug gap and combustion pressure were measured simultaneously In a constant volume chamber, To induce the stratified propane-air mixture distribution near the spark plug, counter-flow typed mixture injection system was used under the constant mean equivalence ratio $\Phi$$\_$mean/= 1.0 The instantaneous equivalence ratio was measured by a single-shot Raman scattering with narrow-band KrF excimer laser. The measuring error was within the limit of $\pm$ 3.5% provided that the proposed method was applied to the measured Raman signals. Judging from mass fraction burned derived from the measured pressure, the optimum combustion characteristics were shown under the condition that the local equivalence ratio in the spark plug was near 1.28$\pm$0.04, and these characteristics were more remarkable at the initial stage of combustion.