• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.17 no.2
• /
• pp.127-137
• /
• 2019

Zr electrorefining is demonstrated herein using Zirlo tubes in a chloride-fluoride mixed molten salt in the presence of $AlF_3$. Cyclic voltammetry reveals a monotonic shift in the onset of metal reduction kinetics towards positive potential and an increase in intensity of the additional peaks associated with Zr-Al alloy formation with increasing $AlF_3$ concentration. Unlike the galvanostatic deposition mode, a radial plate-type Zr growth is evident at the top surface of the salt during Zr electrorefining at a constant potential of -1.2 V. The diameter of the plate-type Zr deposit gradually increases with increasing $AlF_3$ concentration. Scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDX) and X-ray photoelectron spectroscopy (XPS) analyses for the plate-type Zr deposit show that trace amount of Al is incorporated as Zr-Al alloys with different chemical compositions between the top and bottom surface of the deposit. Addition of $AlF_3$ is effective in lowering the residual salt content in the deposit and in improving the current efficiency for Zr recovery.

• Journal of agriculture & life science
• /
• v.52 no.6
• /
• pp.27-36
• /
• 2018

Recently, the demand for new cultivar of oriental mustard(Brassica juncea) is increased as the consumption of oriental mustard has increased dramatically in the market due to Kimchi is attracting the world's attention. However, absence of seed supply system can cause many problems including inbreeding depression due to self seed production, deterioration of the seed purity and heterogeneity of commercial seed. To establish the $F_1$ variety breeding system of oriental mustard, pure line and inbred lines were screened from inbreeding genetic resources. Male-sterile line was also selected from breeding combinations for the quality improvement of mustard. The combining ability from(Indojasai ${\times}$ Goheungdamyang) combinations and isolation line of(MS910 ${\times}$ Japan red mustard 8 ${\times}$ Ganghwa mustard 9) was highest, thus these lines were selected as parental lines. PCR(Polymerase Chain Reaction) and gene sequence analysis revealed that the genes related to CMS(orf263, orf220, and orf288) were distributed in mitochondria. The isolated lines from this study also showed good performance in yield test and farmhouse prove test.

• Korean Journal of Environment and Ecology
• /
• v.35 no.2
• /
• pp.115-125
• /
• 2021

This study surveyed the population ecology of Acheilognathus chankaensis (Pisces: Acheilognathinae) in the vicinity of the Churyeongcheon (Stream) and Seomjingang (River) in Jeonbuk, Korea, from February 2006 to May 2007. The survey found the habits mainly in the slow-flowing waters having sand, mud, and gravel bottoms. Age groups estimated by the standard length-frequency distribution of the population indicated that the one-year-olds were 30-46 mm long, the two-year-olds were 47-58 mm long, the three-year-olds were 59-68 mm long, and the four-year-olds were longer than 69 mm. The gonadosomatic index (GSI) and the ratio of ovipositor length/standard length were the highest in March (♀: 12.9%, ♂: 5.0%) and in April (46.3%), respectively. The ratio of mature egg diameters that were 1.6 mm was highest in May (13.2%). The comprehensive analysis of spawning characteristics showed that the spawning season was from March to June with water temperatures in 11.5-22.5℃, and the sex ratio of female:male was 1:1.13. The fecundity in the ovaries and the number of mature eggs were 318±174.5 (50~583) and 220±139.2 (50~406), respectively. The size of the mature eggs was 2.04±0.110 mm on the long axis and 1.55±0.100 mm on the short axis for the study period. Gut contents of A. chankaensis were mainly phytoplankton such as the genera Fragilaria, Synedra, Navicular, Cymbella (Bacillariophyceae), and Cosmarium (Chlorophyceae).

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.22 no.1
• /
• pp.275-284
• /
• 2021

Survival analysis was used to analyze whether there is a difference in the effect of leverage on corporate failure according to the firm size. A total of 25,250 (year-company) companies listed on the Korea Stock Exchange and KOSDAQ market from 1999 to 2019 were analyzed. First, the increase in leverage generally acts as a factor that increases the possibility of corporate failure. On the other hand, the increase in the trade payable ratio lowered the possibility of failure of the company. The increase in corporate trade payable was perceived as a factor in reducing the possibility of corporate failure because it was considered the active development of business activities or active use of interest-free debt rather than leading to an increase in corporate risk. Second, a higher leverage ratio and trade payable ratio in large firms lowered the possibility of corporate failure. In the SMEs, all types of leverage increases are a factor that increases corporate failure. Overall, the effect of leverage on corporate failure differs according to the size of the company.

• Knowledge Management Research
• /
• v.22 no.2
• /
• pp.247-268
• /
• 2021

Investors mainly use PER and PBR among financial ratios for valuation and investment decision-making. I conduct an analysis of two basic financial ratios from a statistical perspective. Financial ratios contain key accounting numbers which reflect firm fundamentals and are useful for valuation or risk analysis such as enterprise credit evaluation and default prediction. The distribution of financial data tends to be extremely heavy-tailed, and PER and PBR show exceedingly high level of kurtosis and their extreme cases often contain significant information on financial risk. In this respect, Extreme Value Theory is required to fit its right tail more precisely. I introduce not only GPD but exGPD. GPD is conventionally preferred model in Extreme Value Theory and exGPD is log-transformed distribution of GPD. exGPD has recently proposed as an alternative of GPD(Lee and Kim, 2019). First, I conduct a simulation for comparing performances of the two distributions using the goodness of fit measures and the estimation of 90-99% percentiles. I also conduct an empirical analysis of Information Technology firms in Korea. Finally, exGPD shows better performance especially for PBR, suggesting that exGPD could be an alternative for GPD for the analysis of financial ratios.

• Korean Journal of Environment and Ecology
• /
• v.35 no.3
• /
• pp.285-293
• /
• 2021

This study was conducted to elucidate spawning period characteristics and early life development of eight barbel loach, Lefua costata (Balitoridae) at the Jusucheon stream, Okgye-myeon, Gangneung-si, Gangwon-do, Korea between January and December in 2018. The spawning period was estimated to be from May to August, considering the change in the gonad-somatic index, the appearance of young fry, and frequency distribution in egg diameter. It was a multi-spawning type. The gender ratio was 1:0.79 with 1,117 females and 879 males collected. The egg size was 0.24-0.93 mm, with mature and immature eggs found during the spawning period. The size of mature eggs was 0.71±0.02 mm, and the average number of fecundity was 1,786±818 (n=31). Observation of the egg development showed that the fertilized eggs were the sticky, gray, segregated, and demersal type with 0.76±0.03 mm in diameter. The hatching of the embryos began at about 34 hours (hatching rate 50%) after fertilization underwater temperature of 25℃. The average length of the newly hatched pre-larvae was 2.7±0.11 mm. The average length of pre-larvae at 4 days after hatching was 4.5±0.16 mm, and the yolk sac was completely absorbed and entered the post-larvae stage. At 20 days after hatching, the average length of post-larvae was 11.5±0.67 mm, and their fin rays were formed before they transitioned to the juvenile stage. At 100 days after hatching, the average length reached 49.8±2.60 mm, and the appearance and the lateral sideband patterns were similar to those of the adult fish.

• Journal of Korea Water Resources Association
• /
• v.55 no.5
• /
• pp.383-392
• /
• 2022

The restoration of the Nakdong River estuary is one of the most important projects of the Ministry of Environment, Republic of Korea. A real-scale experiment of gate operation was executed from 2019 to 2020, and a pilot operation was performed in 2021. The gate of Nakdong River Estuary Barrier (NEB) is supposed to be continuously opened based on the experiment results. Many critical decisions should be made immediately during the experiment based on the real-time measured data and numerical analysis considering the seawater inflows. The decision-making sequence was made systematically with the accurate estimation of seawater inflow. The estimation of seawater inflow is the main research objective and the equations of seawater inflow were developed, reflecting the structural characteristics of NEB. The inflow equations were developed in two forms, overflow and underflow. ADCP (Acoustic Doppler Current Profiler) was used to measure seawater inflow, check the accuracy of the developed equations, and derive the flow coefficient. The comparison error of the developed equations was about 3% compared to the measured data.

• Journal of Bio-Environment Control
• /
• v.31 no.4
• /
• pp.366-375
• /
• 2022

The monitoring of electricity consumption using Internet of Things (IoT) technology is attracting attention as a technology to reduce operation costs of smart farms. In this study, we propose a method to apply a real-time electrical consumption monitoring system (the e-Gauge system) and utilization of the collected data real-time while a melon-producing smart farm is in operation. For this purpose, the electrical consumption data for the individual smart-farm facilities such as boilers, nutrient distribution systems, automatic controllers, circulation fans, boiler controllers, and other IoT-related utilities were collected during three months of melon cultivation period. By using the monitoring results, the electrical energy consumption pattern was analyzed as an example, and necessary considerations needed to optimally utilize the measurement data were suggested. This paper will be useful in lowering the technological implementation barriers for new researchers to build a electrical consumption monitoring system and reducing trial and errors in the usage of the generated data.

• Journal of the Korean Applied Science and Technology
• /
• v.40 no.3
• /
• pp.374-384
• /
• 2023

Universities that previously targeted in 20s have recently diversified their operation methods, founding purposes, and target. With a significant decrease in the school-age population relative to the number of universities, universities are making their best efforts to secure new students and minimize student attrition. In this study, an online survey was conducted to empirically examine the effects of motivation for major selection and sense of belonging on learning persistence intention among students in beauty-related departments at 2-year and 4-year general universities and cyber universities. The collected data from 119 students at general universities and 113 students at cyber universities were analyzed using SPSS 28. The key findings can be summarized as follows: For general universities, motivation for major selection did not have a significant effect on learning persistence intention, but sense of belonging had a significant positive effect. Additionally, an interaction effect was observed, indicating that as the sense of belonging increased, extrinsic motivation significantly increased learning persistence intention. For cyber universities, intrinsic motivation and sense of belonging among motivations for major selection had a significant positive effect on learning persistence intention, while the moderating effect of sense of belonging in the relationship between motivation for major selection and learning persistence intention was not significant. In summary, for general universities, the factor that influenced students' learning persistence intention was a sense of belonging to the university, while for cyber universities, intrinsic motivation played a significant role. These findings are expected to provide meaningful insights and data for universities to develop effective policies for preventing student attrition.

• Korea Trade Review
• /
• v.42 no.5
• /
• pp.43-69
• /
• 2017

The study examined moderating role of thinking style about causality in the relationship between the perceived brand globalness(PBG) and the brand evaluation. Thinking style about causality is divided into interactionism and dispositionism. Individualism culture shows a tendency of thinking style about causality to dispositionism, and collectivist cultures shows a tendency for interactionism. We conducted a survey on Korean college students who represent collectivist cultures and foreign students from countries of individualistic culture and analyzed data through structural equation modeling. Analysis result showed that the higher the respondents perceived PBG, the higher they perceived brand quality, brand quality, and brand price. However, it showed that PBG has greater positive effects on perceived brand quality and perceived brand reputation among Korean students than students from individualistic cultures. On the other hand, the effects of PBG on perceived brand price did not show any significant difference between Korean students and students from individualist cultures. Thus, we can conclude that thinking style about causality plays a moderating role in the relationship between PBG and perceived brand quality and brand reputation, while it does not do so between PBG and perceived brand price.