• Nuclear Engineering and Technology
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• v.53 no.4
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• pp.1284-1288
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• 2021

In this work, we propose and design a GaN-based diode with a p-doped GaN (p-GaN) multi-well structure for high efficiency betavoltaic (BV) cells. The short-circuit current density (J_SC) and opencircuit voltage (V_OC) of the devices were investigated with variations of parameters such as the doping concentration, height, width of the p-GaN well region, well-to-well gap, and number of well regions. The J_SC of the device was significantly improved by a wider depletion area, which was obtained by applying the multi-well structure. The optimized device achieved a higher output power density by 8.6% than that of the conventional diode due to the enhancement of J_SC. The proposed device structure showed a high potential for a high efficiency BV cell candidate.

• Journal of Soil and Groundwater Environment
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• v.15 no.1
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• pp.39-49
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• 2010

Drilling at unconsolidated layer can make the aquifer disturbed and reduce a productivity of groundwater well. Surge block and air surging were applied to a pumping well located in Jeungsan-ri, Changnyung-gun, to improve a well efficiency by removing clogging and fine-grained slime. Two experimental log-linear equations, $y_1=-0.1769\;ln(x_1)+0.4960$ and $y_2=-84.3358\;ln(x_2)+512.8162$, were proposed in this site, in which $x_1$ and $x_2$ are the number of surging event, $y_1$ is the amount of slime, and $y_2$ is a recovery time of groundwater level after air surging. Well loss exponent (P) decreased after surging, from 3.422 to 1.439, and the groundwater inflow from aquifer happened in all directions around a well with gradually increasing the homogeneity in a local aquifer's hydraulic property. It was revealed that long-term well development should be done in the pumping well which is located in unconsolidated sediments to increase a well productivity.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.34 no.5
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• pp.43-50
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• 2018

The temperature of underground water generally remains constant regardless of the season. therefore, it is possible to get plenty of energy if we use characteristics of underground water for both cooling and heating. This study evaluates efficiency of real size coaxial and U-tube type complex geothermal system which is combined with underground water well. This study also evaluates relative efficiency/adaptability through comparison with existing geothermal systems(vertical closed loop system, open loop system(SCW)). The heat exchange capacity of complex geothermal system according to temperature difference between circulating water and underground water shows very high significance by increasing proportionally. The temperature change of underground water according to injection energy, shows very high linear growth aspect as injection thermal volume heightens. As a result of evaluation of heat exchange volume between complex geothermal system and comparative geothermal system, coaxial type has 26.1 times greater efficiency than comparative vertical closed type and 2.8 times greater efficiency than SCW type. U-tube type has 26.5 tims greater efficiency than comparative vertical closed type and 2.8 times greater than SCW type as well. This means complex geothermal system has extremely outstanding performance.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1993.10a
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• pp.217-226
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• 1993

As results of not selecting and using farm well pump properly , it's running regime is far away from high efficient zone and running efficiency of farm well pump is lower. The paper analyses unhealthy tendencies of technical state of diving-electric pump, deep well and centrifugal pump which are commonly used in our country. The paper also summarizes several technical innovation plans to raise efficiency : stage change plan, diameter change plan, speed change plan and synthetic technical innovation . Each plan gives a detailed introduction of designing and construction manners, through practical measuring , the synthetic efficiency of innovated well pumps raise above 30 percent. Economic benefit is evident.

• Nuclear Engineering and Technology
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• v.50 no.3
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• pp.462-469
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• 2018

The background spectrum of a $3^{{\prime}{\prime}}{\times}3^{{\prime}{\prime}}$ NaI(Tl) well-type scintillation SILENA detector was measured without shielding, in 6 cm thick lead shielding, and with 2 mm thick electrolytic copper covering the detector inside the lead shielding. The relative remaining background of the lead shield lined with copper was found to be ideal for low-level environmental radioactive spectroscopy. The background total count rate in the (20-2160 KeV) was reduced 28.7 times by the lead and 29 times by the Cu + Pb shielding. The effective reduction of background (1.04) by the copper mainly appeared in the energy range from X-ray up to 500 KeV, while for the total energy range the ratio is 1.01 relative to the lead only. In addition, a strong relation between the full-energy peak absolute efficiency and the detector well height was found using gamma-ray isotropic radiation point sources placed inside the detector well. The full-energy peak efficiency at a midpoint of the well (at 2.5 cm) is three times greater than that on the detector surface. The energy calibrations and the resolution of any single energy line are independent of the locations of the gamma source inside or outside of the well.

• Journal of environmental and Sanitary engineering
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• v.5 no.1
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• pp.83-92
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• 1990

Adapting two step aeration system to a waste water treatment of W-paper manufactory as Full-Scale Plants, we drew a following conclusion from its practical working. 1. Because BOD removal efficiency was 20% in A-Stage, 90% in B-Stage and total removal efficiency was 97%. It worked treatment plant well and was suitable for effluent water standard as well. Because COD removal efficiency was 42% in A-stage, 71% in B-stage and the total removal efficiency was 94% COD control was possible in effluent water quality. 2. Treatment efficiency according to a load capacity was average 20% in 1.401 BOD kg/m3/d load of A-Stage and average 90% in 0.273 BOD kg/$\textrm {m}^3$ / d load of B-Stage. 3. Treatment efficiency according to a ratio of F/M was 2.657--5.024 kg BOD/kg MLSS/d in A-Stage and BOD removal efficiency was 16-261 in the same stage. The ratio of F/M was 0.068-0.094 kg BOD /kg MLSS/d and BOD removal efficiency ratio was 85-94%. Therefore treatment efficiency could be kept stably and volume of aeration tank could be reduced wholly. 4. Treatment efficiency according to MLSS appeared BOD 20%. COD 42%, in A-Stage and removal efficiency appeared BOD 90%, COD 71% in B-Stage. They were suitable for plan condition. 5. Because of working of complemented treatment plant by AB-Process. 20,000,000 Won a month was saved than the ordinary working cost. Therefore, it was assumed that invested cost could be recollected in 19 months or so consequently.

• Current Optics and Photonics
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• v.2 no.5
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• pp.468-473
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• 2018

We investigate the temperature dependence of efficiency droop in InGaN/GaN multiple-quantum-well (MQW) blue light-emitting diodes (LEDs) in the temperature range from 20 to $80^{\circ}C$. When the external quantum efficiency (EQE) and the wall-plug efficiency (WPE) of the LED sample were measured as injection current and temperature varied, the droop of EQE and WPE was found to be reduced with increasing temperature. As the temperature increased from 20 to $80^{\circ}C$, the droop ratio of EQE was decreased from 16% to 14%. This reduction in efficiency droop with temperature can be interpreted by a temperature-dependent carrier distribution in the MQWs. When the carrier distribution and radiative recombination rate in MQWs were simulated and compared for different temperatures, the carrier distribution was found to become increasingly homogeneous as the temperature increased, which is believed to partly contribute to the reduction in efficiency droop with increasing temperature.

• The Journal of the Korea Contents Association
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• v.12 no.2
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• pp.232-242
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• 2012

The purpose of this study was to analyze the multiple regression between the psychological well-being, Empathy ability Scale and Job Efficiency at relationship among on Teacher's job satisfaction among elementary, middle, high the whole country. It aims to find a method that can improve teacher's job satisfaction. The subjects for this study were 308 teacher's composed of 196 out of elementary school teachers, 62 out of middle school teachers and 50 out of high school nation wide. The result and discussion are as follows:First, if we take a look teacher's psychological well-being, Empathy ability Scale and Job Efficiency autonomy and school administration, compensation system, personal growth and school administration, compensation system, working environment, purpose of life and school administration, positive interpersonal relationships, self acceptance among subordinate variables of psychological well-being, empathy ability scale, job efficiency of teachers at are all relevant to of subordinate variables except compensation system. Second, as a result of the multiple regression analysis, the significant variables which affect teacher's job satisfaction are ranked in the order of human relationships, self acceptance, emotional factors. whole all variables are not significant.

• Journal of Families and Better Life
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• v.26 no.6
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• pp.71-82
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• 2008

The purpose of this study was to identify factors affecting the purchases of well-being tea drinks based on the analysis of demographic characteristics, well-being oriented consumer behaviors, and consumer consciousness toward well-being tea drinks. The subjects of this study were undergraduates and graduate students in Seoul. The findings were summarized as follows: 1. Well-being oriented consumer behavior patterns were categorized in three factors; non-dietary life, selective dietary life, and regular/temperate behavior and consumer consciousness toward well-being tea drinks were categorized in two factors; habit/ familiarity and health/ economical efficiency. 2. Multiple regression analysis was used for finding out factors affecting the purchases of well-being tea drinks; independent variables were demographic characteristics(sex, monthly average family income and the amount of personal expenditure), well-being oriented consumer behavior factors and consumer consciousness factors toward well-being tea drinks. Weekly purchase frequency of well-being tea drinks was defined as a dependent variable. As a result, the purchases of well-being tea drinks were influenced in order of regular/temperate behavior, the consciousness of health/ economical efficiency, the amount of personal expenditure and the consciousness of habit/ familiarity. Especially, regular/temperate behavior negatively affected the purchases of well-being tea drinks.

• Korean Journal of Agricultural Science
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• v.44 no.3
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• pp.424-439
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• 2017

This study was undertaken to examine the profit efficiency and its determining factors, the investment opportunity, and the challenges of shea butter producers in the northern region of Ghana. The methods employed in this research were the Stochastic Profit Frontier (SPF) model, gain-cost and investment return analyses, as well as Kendall's W statistic using primary data collected from 120 purposively-selected respondents. Results from the analysis indicated that profit efficiency was positively influenced by sex, household size, marital status, educational level, transportation cost, store rent, and price of shea nut with a gain in profit efficiency of 58.5%. The investment analysis demonstrated a net gain per person of $8,077 equivalent to GH₵ 28,270 Ghanaian cedi (GH₵) using 2016 exchange rate (GH₵ 3.5 = $1). Among the challenges identified, the poor quality of shea nuts was the most prioritised challenge with 72.8% agreement among the respondents. Based on these findings, it was recommended that proper training and education, as well as improvement in shea nut quality, should be promoted to improve the profit efficiency of shea butter producers.