• 대한기계학회논문집B
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• 제31권6호
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• pp.539-546
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• 2007

An experimental study was performed to investigate the characteristics of chemiluminescence in a radiant burner, varying the excess air ratio from 0.91 to 1.67 at firing rate 80.5 to 134.2 kW/m2 on $OH^*,\;CH^*,\;{C_2}^*$ in LNG-Air premixed flames. The signals from electronically excited states of $OH^*,\;CH^*,\;{C_2}^*$ were detected using a Intensified Couple Charged Detector (ICCD) camera. The measurements of exhausted emission were made to investigate the correlation between chemiluminescence and emissions. The chemiluminescence intensity was increased with increase of firing rate like characteristics of $NO_x$ emission. $NO_x$ also increased with increase of firing rate and excess air ratio. It is found that offset of firing rate is more dominant excess air ratio $NO_x$ emission. The maximum chemiluminescence intensity occurs near the stoichiometric excess air ratio or lean conditions in case of high firing rate and the maximum intensity occurs rather than rich conditions in case of relatively low firing rate. Amount of $NO_x$ emission is maximum at near stoichiometric excess air ratio, which is chemiluminescence intensity is maximum.

• 한국초등수학교육학회지
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• 제21권1호
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• pp.215-241
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• 2017

본 연구에서는 비와 비율을 지도에 대한 교사의 이해 정도를 알아보기 위하여 비와 비율 지도에 대한 교사의 교수학적 내용 지식(PCK)을 질문지와 면담을 통해 분석하였다. 연구 결과, PCK의 내용 측면에 있어서 교사는 비와 비율의 개념을 정확하게 이해하고 실생활 맥락과 연계해서 비와 비율을 지도할 필요가 있으며, PCK의 교수 방법 및 평가에 대한 지식의 관점에서 비와 비율에 대한 교수 목표를 강화하고 교수 방법에 있어서도 활동 중심으로 바뀔 수 있도록 교사들의 PCK를 강화할 필요가 있다. 그리고 학생 이해 지식의 관점에서 교사의 PCK는 교사의 설명 이외에 오류 지도 방법을 다양화하고 정의적 측면을 수업에 연계할 수 있도록 해야 한다. 마지막으로 수업 상황에 대한 지식의 관점에서 교사는 주체적 관점에서 교과서 활동을 재구성하고, 활동의 특성에 맞게 수업 집단을 다양화 할 필요가 있다. 본 연구 결과는 설문과 면담을 통한 비와 비율에 대한 교사의 PCK가 실제 수업과 어떠한 연관성을 갖고 있는지에 대한 추후 연구를 제안한다.

• Advances in materials Research
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• 제13권2호
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• pp.129-140
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• 2024

This study evaluates the ratio of Toluene di-isocyanate (TDI) functional group isocyanate (NCO) to the binder functional hydroxyl group (OH) in HTPB/AP/Al-based propellants on their mechanical properties, flow rate, and viscosity to determine the limitations of NCO/OH in the composition of solid propellants. The propellants consisted of hydroxyl-terminated polybutadiene (HTPB) polyurethane (PU), aluminum (Al) and tri-modal ammonium perchlorate (AP). The tri-modal AP consisted of 30% of coarse AP, 30% of medium AP, and 8% of fine AP. The ratio of NCO/OH varies from 0.73 to 0.85, with two binder percentages of 10.5% and 12%. An increase in NCO/OH ratio with 10.5% binder provided 20%, 95%, and 8 to 9% increments in UTS, modulus, and hardness, respectively. However, the propellant elongation, density, and flow rate decreased by 170%, 0.2%, and 11-12%, respectively. Viscosity increased 20% based on initial hour reading. The 12% binder provides 27%, 47%, and 5~6% an increment of UTS, modulus and hardness respectively. However, the propellant elongation, density, and flow rate decreased by 47%, 0.17% and 27%, respectively. The viscosity increased 30% based on initial hour reading. This study suggests the NCO/OH value of 0.77 and 10.5~11% binder content in propellant based on the mechanical properties, flow rate, and viscosity for better processing and pot life.

• 보건의료산업학회지
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• 제9권4호
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• pp.197-206
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• 2015

Objectives : This study presents comparison results of the correlations between ODA grants and health indicators among 23 countries in Asia. Methods : Data from 2005~2013 were collected through the World Development Indicator (WDI) provided by the World Bank (WB). The health-related variables used in this study included the maternal mortality ratio, infant mortality rate under five, infant mortality rate, incidence of tuberculosis, and prevalence of AIDS. Results : Based on the results, there were positive correlations between ODA grants and health indicators, which means that the overall ODA grants would drop when the health indicators improved. As for differences in the health indicators by income groups among the countries, there were differences in the maternal mortality ratio, infant mortality rate under five, infant mortality rate, and overall ODA grants. The maternal mortality ratio, infant mortality rate under five, and infant mortality rate were lower in the order of upper middle, lower middle, and poorest income countries. Conclusions : The findings raise a need for the integrated and horizontal development of Goals 4, 5 and 6 of MDGs in the ODA projects of health sector in the future.

• 한국초등수학교육학회지
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• 제14권3호
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• pp.769-788
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• 2010

본 연구는 우리나라 초등학교 수학 교과서와 미국 MIC 교과서의 비와 비율 관련 단원을 전반적인 비교와 구체적인 비교로 특징을 분석하였다. 이를 바탕으로 교육과정과 비와 비율 관련단원 내용의 문제점과 시사점을 찾아 수학과 교육과정 및 교과서 개발, 수학 학습지도 방법 개선의 기초 자료를 제공하는 데 그 목적을 둔다.

• 대한수학교육학회지:수학교육학연구
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• 제18권3호
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• pp.309-333
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• 2008

본 연구에서는 비와 비율의 교수 학습과 관련된 선행 연구를 고찰하고, 현행 초등학교 교과서의 문제점을 분석하였다. 선행 연구 고찰과 현행 교과서의 문제점 분석을 토대로 교과서를 새롭게 재구성하였으며, 재구성된 교과서를 활용하여 실제 교수 학습을 실시하고 그 과정에서 나타난 재구성 교과서의 적절성과 한계, 학생들의 비와 비율 개념화 과정 등을 확인하였다. 현행 교과서와 다르게, 본 연구의 재구성 교과서에서는 비율, 백분율과 비의 값, 비로 지도 순서를 바꾸었으며, 이는 적절한 것으로 확인되었다. 또한 재구성 교과서에서는 상대 비교와 절대 비교, 가법적 사고와 승법적 사고 등을 다루었으며, 이는 학생들의 비와 비율 개념 이해에 도움을 주는 것으로 확인되었다. 한편, 재구성 교과서에 제시된 다양한 맥락들 중에서 일부 맥락은 학생들의 인지적 혼란을 야기하는 것으로 확인되었다.

• 한국농공학회지
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• 제39권6호
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• pp.67-79
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• 1997

The perpose of this study was to suggest the experimental characteristic of the Cherepnov Water Lifter following the drain mode. The Cherepnov Water Lifter(CWL), which is powered by the potential energy of water, can be set to operate automatically when the water m a tank is drained. In this study, a CWL is constructed in the valve drain controlling mode(VCM) and the siphon drain controlling mode(SCM), and a pressure transducer is installed. It was found that, in the VCM, intake flow volume is proportional to both delivery flow volume and drain flow volume. In the SCM, intake flow volume is proportional to drain flow volume, and the average delivery rate is proportional to both efficiency and the water utilization ratio. Also, in the VCM, the water utilization ratio is 35~49%, efficiency is 62~9O%, average delivery rate is 12.8~81.2$cm^3$/s, and the average drain rate is 14.O~91.5c$cm^3$/s. On the contrary in the SCM, the water utilization ratio is 1.7~38%, efficiency is 3~58%, average delivery rate is 3.1 ~69.2$cm^3$/s, and the average drain rate is shown as 114.5~ 183$cm^3$/s. As a result of the water utilization ratio, efficiency, average delivery rate, and average drain rate are compared, the VCM is found to be superior and the more economical mode. However, the VCM requires manpower and electricity to operate the electronic machinery involved, while the SCM requires no manpower or electricity at all. An economic evaluation of these differences will be necessary in the future. Also, in the SCM, studies to improve water utilization ratio and efficiency, to find the optimum height of the siphon for decreasing the average drain rate, and to determine the radius of curvature of throat have to be conducted in advance, since a large flow rate is drained during the priming action of the siphon.

• The Korean Journal of Physiology
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• 제5권2호
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• pp.15-27
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• 1971

Physiological analysis of the physical exercise was made on 9 subjects performing mountain climbing. The course between two points (256 and 516 meters altitude) was 1,300 meters in distance and difference of vertical height was 260 meters making the mean grade of 20%. In the field, the heart rates during uphill or downhill walk were recorded by EKG radio-telemetry. In the laboratory, oxygen consumption was obtained by the recorded heart rates, using individual heart rate vs oxygen consumption diagram obtained by treadmill test. the following results were obtained. 1. Uphill walk time was 36.5 minutes, and during this period the mean heart rate was 149.0 heats/min and peak heart rate was 169.2 beats/min. The total heart beats during the uphill walk was 5.433 beats. 2. The ratio of individual mean heart rate during the uphill walk to the maximal heart rate distributed between 66.6% and 98.3%, and the mean of the total group was 83.1%. The ratio of peak heart rate of uphill walk to the maximal heart rate was 94.5% in the group. Thus uphill walk of a 20% grade mountain course was an exhaustive exercise. 3. Oxygen consumption during uphill walk was 2.22 l/min (ranged between 1.79 and 2.70 l/min) and the ratio of this to the resting oxygen consumption was 8.31. The peak value of oxygen consumption during uphill walk was 2.73 l/min and the ratio of this to the resting oxygen consumption was 10.39. 4. Energy expenditure during uphill walk showed a mean of 11.1 kcal/min and the peak expenditure rate was 13.6 kcal/min. The total energy expenditure during 36.5 minutes of uphill walk was 396 kcal. 5. In downhill walk, the time was 31.7 minutes, mean heart rate was 118.4 (ranged between 100.1 and 142.7) beats/min, and the peak heart rate was only 129.4 beats/min. The ratio of mean heart rate to the maximal heart rate was 66.3%. Total heart beats during downhill walk was 3,710 beats. The ratio of downhill oxygen consumption to the resting consumption was 5.70. The rate of energy expenditure was 7.5 kcal/min, and the total onery expenditure during the 31.7 minutes of downhill walk was 228 kcal. 6. The effect of training was manifest in the uphill walk and not in the downhill walk. After training in mountain course walk, i) the uphill time was shortened, ii) mean heart rate increased, iii) time vs heart rate curve became smooth and showed less frequent zig-zag, i.e., the depth of trough on the curve decreased and the magnitude was less than 10 beats. In non-trained subject the depth of trough on the curve was greater than 50 beats and appeared more frequently. 7. Mountain climbing is a good health promotion exercise. For the promotion of health the reasonable amount of uphill mountain walk exercise in a 20% grade course is a walk for 40 or 50 minutes duration once a week.

• 생태와환경
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• 제52권2호
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• pp.171-177
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• 2019

Smart farm is a breakthrough technology that can maximize crop productivity and economy through efficient utilization of space regardless of external environmental factors. This study was conducted to investigate the optimal growth and physiological conditions of Chinese matrimony vine (Lycium chinense) with LED light sources in a smart farm. The light source was composed of red+blue and red+blue+white mixed light using a LED system. In the red+blue mixed light, red and blue colored LEDs were mixed at ratios of 1:1, 2:1, 5:1, and 10:1, with duty ratios varied to 100%, 99%, and 97%. The experimental results showed that the photosynthetic rate according to the types of light sources did not show statistically significant differences. Meanwhile, the photosynthetic rate according to the mixed ratio of the red and the blue light was highest with the red light and blue LED ratio of 1:1 while the water use efficiency was highest with the red and blue LED ratio of 2:1. The photosynthetic rate according to duty ratio was highest with the duty ratio of 99% under the mixed light condition of red+blue+white whereas the water use efficiency was highest with the duty ratio of 97% under the mixed light of red+blue LED. The results indicate that the light source and light quality for the optimal growth of Lycium chinense in the smart farm using the LED system are the mixed light of red+blue (1:1) and the duty ratio of 97%.

• 대한예방의학회:학술대회논문집
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• 대한예방의학회 1994년도 교수 연수회(역학)
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• pp.158-163
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• 1994

Slightly elevated urinary albumin excretion rate (microalhuminuria) is a marker of early diabectic nephropathy, but it is unclear if the established definition of microalbuminuria ($20-200{\mu}g/min$) is correct for children and adolescents. We investigated th.: albumin excretion rate, albumin/creatinine ratio and urinary albumin concentration in 150 healthy schoolchildren and adolescents to (a) obtain a reterence value for albumin excretion rate, (b) relate albumin excretion to pubertal stages and (c) evaluate albumin/creatinine ratio and morning albumin concentration as screening methods for elevated albumin excretion rate. Albumin concentration was measured by immunoturbidimetry in timed overnight urine samples. The albumin excretion showed a skewed distribution (geometric mean $3.2{\mu}g/min$, 95 percentile ($15.1{\mu}g/min$). In girls. a peak in the albumin excretion rate was found at the pubertal stage 4 (Tanner) and in boys at stage 5. Albumin/creatinine ratio of 2.5 mg/mmol as a screening level for elevated albumin excretion ($15{\mu}g/min$) showed a high positive (0.88) and negative (0.99) predictive value.