• Journal of agricultural medicine and community health
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• v.48 no.1
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• pp.28-40
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• 2023

Objectives: This study aimed to identify the level of self-assessment of life satisfaction and various factors related to the life satisfaction of Korean physicians. Methods: This study is a secondary data analysis using the 2016 Korean physician survey Korean Physician Survey(KPS) data collected by the Research Institute for Healthcare Policy of the Korean Medical Association. The member database(DB) of the Korean Medical Association was used for sampling and the target population was formed and surveyed by using stratified quota sampling. A questionnaire was sent by E-mail as an online survey method and was conducted for a total of 7 weeks from November 21, 2016 to January 8, 2017. The final number of respondents was 8,564 (response rate 13.8%). In this study, a total of 7,228 physicians, excluding residents and public health doctors who are currently treating patients directly, were studied. Factors affecting the life satisfaction of physicians were analyzed using ordinal logistic regression analysis. Results: The physical factors positively related to the life satisfaction of physicians were those who were in their 60s, female, and thought they had good health status. As for psychological factors, stress was low. As for economic factors, satisfaction with income was high. As for social factors, the physicians lived with their families and were satisfied with the time they could spend with them. Also, the physicians were satisfied with the social respect they received as a doctors. Conclusions: Based on the results of this study, it is thought that a multifaceted approach is needed to increase the life satisfaction of physicians.

• Journal of Korean Port Research
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• v.6 no.2
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• pp.65-92
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• 1992

The Korean central government has not appreciate the full extent of the impact of seaports on the national economy. As a consequence port investment has not been given sufficient priority and capacity has failed to keep pace with demand. The principal reason for this failure is the fact that the linkages (or relationships) of the port transport industry with other sectors have not been quantified and fully appreciated. To overcome this dificiency this paper developed a port input-output model to determine the economic impact of the port industry on the national economy. This impact study was conducted by analysing the impact of the Korean port industry upon the national economy from the macroeconomic viewpoint, and identifying the spreading effects of port investments upon the nation's economy. The analysis of the economic impact of the port industry suggests that its contribution to the Korean economy is substantial. What the model shows is, in quantifiable terms, there are the strong economic linkages between the port industry and the other sectors of the national economy. The contribution of the port industry to the Korean economy was summarised in the Conclusion section.

• Journal of The Korean Society of Grassland and Forage Science
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• v.43 no.1
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• pp.28-34
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• 2023

This experiment was carried out to determine effects of seed rate of native grasses, called native summer forage crops (NSFC), on their growth characteristics and yields in no-tillage paddy fields in central provinces. NSFC cultivation was performed according to the agricultural guidelines of the Rural Development Administration (RDA) during 2020 to 2022. Echinochloa crusgalli 'Jeju native', Setaria viridis 'Korean native type', Digitaria sanguinalis 'Korean native type') were sown by various seed rate in the experimental field (3m × 4m plot) of Department of Animal Resources Development, Seonghwan-eup, Cheonan, Korea in late-May or early-June for 3 years and harvested in middle-September. Dry matter yields (DMY) in Echinochloa crusgalli and Setaria viridis increased as increasing seed rate. DMY in 40 kg ha^-1 of Echinochloa crusgalli was the highest and DMY in 60 kg ha^-1 of Setaria viridis was the highest. However, All treatments of Digitaria sanguinalis showed similar DMY. Yields of NSFC were the order of Echinochloa crusgalli (9,681~11,092 kg ha^-1) > Digitaria sanguinalis (8,311~9,023 kg ha^-1) >etaria viridis (3,145~4,749 kg ha^-1). The contents of crude protein in NSFC were the order of Digitaria sanguinalis > Echinochloa crusgalli > Setaria viridis. The contents of ADF and NDF in NSFC were the order of Echinochloa crusgalli > Digitaria sanguinalis > Setaria viridis. As shown in above results, we suggest that introduction of NSFC is one of the most important skills in order to stably increase yields of forage crops for utilization of the double cropping system in no-tillage paddy fields.

• Journal of Life Science
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• v.32 no.3
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• pp.202-209
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• 2022

The green alga Chlamydomonas reinhardtii, a unicellular haploid eukaryote, has long been used by researchers and industries as a cell factory to produce high value-added microalgae substances using genetic modification. Microalga K01, presumed to be Chlamydomonas, was isolated from 12 freshwater samples from the Chungcheong and Jeolla regions to replace C. reinhardtii, an introduced species currently used in most basic and industrial research. The isolated K01 strain was identified as C. reinhardtii through morphological and phylogenetic studies of the 18S rDNA gene sequence (NCBI accession number KC166137). The growth and lipid content of the isolated C. reinhardtii K01 were compared with three wild and four mutant strains in TAP medium, and it was found that the K01 strain could produce 1.74×10⁷ cells/ml by the third day of culture. The growth rate of C. reinhardtii K01 was 1.5 times faster than UTEX2244, which showed the highest number of cells (1.20×10⁷ cells/ml) among the compared strains. The lipid content of the isolated C. reinhardtii K01 (20.67%) was similar to those of the wild strains, although the fatty acid oleate C18:1 was not detected in the isolated strain but was identified in the seven others. The cell density of the isolated strain increased to 0.87 g/l during a six-day culture in BG11 medium, where nitrate (NaNO₃) was introduced as a nitrogen source, while the seven acquired strains showed almost no cell proliferation.

• The Journal of Engineering Geology
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• v.32 no.1
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• pp.113-126
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• 2022

The tectonic history of the Chukchi Abyssal Plain in the Amerasia Basin, Arctic Ocean, has not been fully explored due to the harsh conditions of sea ice preventing detailed observation. Existing models of the tectonic history of the region provide contrasting interpretation of the timing of formation of the crust (Mesozoic to Cenozoic), crust type (from hyper-extended continental crust to oceanic crust), and formation process (from parallel/fan-shaped rifting to transformation faulting). To help determine the age of the oceanic crust, the geothermal gradient was measured at three stations in the south of abyssal plain at depth of 2,160-2,250 m below sea level. Heat flow measurement stations were located perpendicular to the spreading axis over a 40 km-long transect. In-situ thermal conductivity measurement, corrected by the laboratory test, gave observed marine heat flows of 55 to 61 mW/m². All measurements were taken during Arctic expeditions in 2018 (ARA09C expedition) and 2021 (ARA12C expedition) by the Korean ice-breaking research vessel (IBRV) Araon. Given the assumption of oceanic crust, the results correspond to formation in the Late Cretaceous (Mesozoic). The inferred age supports the hypothesis of formation activated by the opening of the Makarov Basin during the Late Mesozoic-Cenozoic. This would make it contemporaneous with rifting of the Chukchi Border Land immediately east of the abyssal plain. The heat flow data indicate the base of the gas hydrate stability zone is located 332-367 m below the seafloor, this will help to identify the gas hydrate-related bottom simulating reflector in the future seismic survey, as already identified on the Chukchi Plateau. Further geophysical surveys, including heat flow measurements, are required to increase our understanding of the formation process and thermal mantle structure of the abyssal plain.

• Journal of Korea Water Resources Association
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• v.56 no.1
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• pp.53-62
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• 2023

Recently, due to the influence of climate change, the occurrence of damage to heavy rain is increasing around the world, and the frequency of heavy rain with a large amount of rain in a short period of time is also increasing. Heavy rains generate a large amount of outflow in a short time, causing flooding in the downstream part of the mountainous area before joining the small and medium-sized rivers. In order to reduce damage to downstream areas caused by flooding, it is very important to calculate the outflow of mountainous areas due to torrential rains. However, the sewage network flooding analysis, which is currently conducting the most analysis in Korea, uses the time and area method using the existing data rather than calculating the rainfall outflow in the mountainous area, which is difficult to determine that the soil characteristics of the region are accurately applied. Therefore, if the rainfall is analyzed for mountainous areas that can cause flooding in the downstream area in a short period of time due to large outflows, the accuracy of the analysis of flooding characteristics that can occur in the downstream area can be improved and used as data for evacuating residents and calculating the extent of damage. In order to calculate the rainfall outflow in the mountainous area, the rainfall outflow in the mountainous area was calculated using MIKE SHE among the MIKE series, and the flooding analysis in the downstream area was conducted through MIKE 21 FM (Flood model). Through this study, it was possible to confirm the amount of outflow and the time to reach downstream in the event of rainfall in the mountainous area, and the results of this analysis can be used to protect human and material resources through pre-evacuation in the downstream area in the future.

• Analytical Science and Technology
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• v.19 no.3
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• pp.263-271
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• 2006

The levels of total PCBs, Co-PCBs and PCDD/Fs in the transformer insulation oil samples obtained using GC/ECD and HRGC/HRMS were ranged from N.D. to 77.3 ppm, from 0.0863 to 2.49 ppm and from N.D. to 0.00241 ppm, respectively. In terms of WHO-TEQ values, Co-PCBs and PCDD/Fs were ranged from 23.3 to 600 pgTEQ/g and from N.D. to 128 pgTEQ/g, respectively (${\Sigma}Co$-PCBs+PCDD/Fs concentration was calculated 24.4~728 pgTEQ/g). Although, the contribution of PCDD/Fs was below 12% in total TEQ concentration, it is suggested contamination of PCDD/Fs in transformer insulation oils. Among 10 samples, 4 samples showed higher concentration than 2 ppm (specific waste criterion of Korea) and Aroclor 1242, 1248, 1254 and 1260 was detected in samples as a single or mixture of Aroclor. It was shown reliable relationship between concentration of Co-PCBs and those of PCDD/Fs (p<0.003), however, was not shown between production year of transformer and concentration of PCBs. The distribution pattern of Co-PCB congeners showed that the ratios of mono-ortho substituted congeners were higher than non-ortho substituted congeners. Among that, PCB-118 congener was predominant. In addition, the OCDD congener was predominated in PCDD/Fs congeners as above 53%. Moreover, the congener pattern of Co-PCBs was similar to that of Aroclor as well as ambient air, which suggested that PCBs volatilization from transformer insulation oil affected the pattern of Co-PCBs in ambient air.

• Korean Journal of Poultry Science
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• v.50 no.2
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• pp.91-99
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• 2023

This study aimed to develop a high-productivity breed of Korean native Samgye chicken. We evaluated the production performance of six Korean native chicken combinations (KNC-SCYC, SCYD, SDYC, SDYD, SYYC, SYYD) and GSP-Hanhyup Korean native chickens, with Baeksemi chickens used as a control group. The performance test was conducted from hatching to 7 weeks of age on 756 chickens, and we measured survival rate, body weight, shank length, feed utility, and carcass yield. The overall survival rate was nearly 100% for all strains. However, body weight showed significant differences between strains at all ages (P<0.01), with Baeksemi weighing 863.8±76.9 g, GSP-Hanhyup weighing 804.7±72.5 g, and KNC-combinations weighing 543.0±61.8 g at 5 weeks of age. The duration needed to reach 850 g was estimated to be 34.5 days for Baeksemi, 37.5 days for GSP-Hanhyup, and 45.8-48.8 days for KNC-combinations. Carcass yield percentage was highest for KNC-SYYD combination at 63.3%, followed by Baeksemi at 60.4%, and GSP-Hanhyup at 56.1%. Shank length at 850 g body weight was 7.6 cm for KNC-SYYD combination, 7.8 cm for Baeksemi, and 8.0 cm for GSP-Hanhyup. The feed conversion ratio at 850 g body weight was 1.81 for Baeksemi, 2.17 for GSP-Hanhyup, and 2.27 for KNC-SCYC combination. Our results suggest that the KNC-SYYD combination and GSP-Hanhyup breed have the potential to be used in Samgye production due to their moderate growth performance, higher carcass yield, and shorter shank length, despite their lower growth productivity and feed efficiency when compared to Baeksemi.

• Korean Journal of Poultry Science
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• v.50 no.3
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• pp.133-141
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• 2023

We conducted a 5 × 5 diallel cross-combination test using 1,060 chickens from pure lines of Korean Rhode-C, -D, Korean Leghorn-F, -K, and Korean Native Yellowish-brown chicken (KNC-Y) to develop a new Korean native chicken layer breeder. The laying performance and combining ability, including livability, body weight, age of first egg-laying, hen-day egg production, and egg weight, were analyzed. The livability from birth to 48 weeks was 72.1±24.0%, with the highest observed in the YC and the lowest in the DK combination (P<0.01). The YC combination exhibited the highest general combining ability (GCA), while the YD combination showed the highest specific combining ability (SCA). Regarding body weight, combinations involving Leghorn showed lighter weights compared to combinations with Rhode and KNC-Y (P<0.01). Additionally, the offspring from the KNC-Y combination reached sexual maturity earlier than those from the Rhode combination. The hen-day egg production was 70.7±12.0%, with the highest seen in the CK combination at 86% (P<0.01). The effects of GCA and SCA on hen-day egg production were similar, with the SCA being highest in the YD combination and the GCA being highest in the Rhode-C. Significant differences in egg weight were observed among the combinations, with the eggs from Rhode and Leghorn combinations being heavier than those from combinations with KNC-Y (P<0.01). In conclusion, the YC and YD combinations, characterized by excellent livability, are highly desirable paternal strains, while the CF and CK combinations, with excellent laying performance and moderate egg weight, are preferred maternal strains for Korean native chicken layer breeders.