• Journal of Drive and Control
• /
• v.21 no.3
• /
• pp.20-27
• /
• 2024

This study aimed to evaluate the impact of mechanizing onion harvesting on labor reduction and work efficiency in Shinan Area. The mechanized harvesting system comprised a stem cutter, digging harvester, and collector. The field tests showed that the average residual stem length after using the stem cutter was 13.22±5.01 cm, with a stem cutting ratio of 91.3% and a damage ratio of 0%. The digging harvester achieved a digging ratio of 100% and a damage ratio of 1.2%, while the collector's damage ratio was 4.1%, loss ratio was 2.7%, and debris mixing ratio was 3.2%. The total working capacity of the mechanized system was 2.3 h/10a, significantly reducing 97.2% of labor time compared to manpower. These results indicate that the mechanization of onion harvesting can effectively reduce labor costs and increase work efficiency. Future research should include performance verification in various environments and an economic analysis of the mechanized system.

• Food Science of Animal Resources
• /
• v.26 no.4
• /
• pp.454-463
• /
• 2006

This study was carried out to investigate the effects of addition of green tea extract material with or without nitrite (0.02 g) on the quality characteristics and reduced nitrite content of emulsion-type sausages during 4 weeks of storage at $4^{\circ}C$. The treatments were; non-added nitrite and green tea extract (0, added nitrite and non-added green tea extract (T1), added nitrite and 0.2% green tea extract (T2), added nitrite and 0.5% green tea extract (T3), and added nitrite and 1% green tea extract (T4). The lightness $(L^*)$ of sausage containing nitrite and green tea extract together were significantly lower than control and T1 (p<0.05). The redness $(a^*)$ of sausage containing only nitrite (T1) and, nitrite and green tea extract at 1% (T4) were significantly higher than control (p<0.05). The total expressible fluid (%) of sausage containing nitrite and green tea extract were significantly lower than control (p<0.05). Cohesiveness of sausage containing green tea extract were significantly lower than control (p<0.05) at 2 and 4 weeks storage period. Addition of nitrite and green tea extract decreased the TBARS values (p<0.05). It was also found that natural extract (green tea) treatments decreased TBARS formation more than only added nitrite (Tl) (p<0.05). The changes of total plate count and coliform plate count were increased during storage time. The total plate count of T1 was higher at 4 weeks of storage period, while the coliform plate count was higher in control at 2 and 4 weeks of storage period compare to other treatments. The residual nitrite content was decreased during storage time in all treatment except control and the effectiveness of decreasing ability was higher with increasing green tea extract.

• Tuberculosis and Respiratory Diseases
• /
• v.46 no.1
• /
• pp.17-24
• /
• 1999

Background : A sizable percentage of tuberculous pleurisy patients are known to have residual pleural thickening(RPT) despite adequate anti-tuberculous chemotherapy. But, the predictive factors related to the development of RPT is not well known. Therefore, we studied to determine which factors are related to the development of RPT after completion of therapy. Methods: By retrospective review of medical records, fifty-eight patients initially diagnosed as having tuberculous pleurisy between March 1995 and January 1998 were separated into two groups : 27 patients in group 1 had RPT on simple chest radiography, while 31 patients in group 2 had no RPT after 6 month of anti-tuberculous chemotherapy. The clinical characteristics, radiologic findings and pleural fluid findings of the two group were compared at the time of diagnosis and during the course of therapy. Results: 47% of patients had RPT after 6 month of chemotherapy, and RPT was more common in man than in women(54% vs 29%, p=0.092). In group 2 patients, complete resorption of pleural lesion occurred rather late stage of therapy(1-2 month: 26%, 3-4 month: 29%, 5-6 month: 45%). Group 1 patients had increased percentage of loculated pleural lesion(26 % vs 19%) and increased white blood cell and lymphocyte count, lactate dehydrogenase level in pleural fluid ($3527\pm5652$ vs $2467\pm2201$/ml, $2066\pm2022$ vs $1698\pm1835$/ml and $1636\pm1143$ vs $1441\pm923$IU/mL respectively) than group 2 at the time of diagnosis, but statistically insignificant. Duration of symptom prior to treatment, size of pleural effusion, presence of parenchymal lung lesion, level of total protein, glucose and adenosine deaminase(ADA)activity in pleural fluid were similar in both group. Conclusion: 53% of tuberculous pleurisy patients showed slow but complete resorption of pleural lesion after 6 month of chemotherapy. But, no clinical, radiological and pleural fluid findings are predictive for the development of RPT.

• Korean Journal of Agricultural Science
• /
• v.14 no.1
• /
• pp.98-133
• /
• 1987

The mechanical and rheological properties of agricultural materials are important for engineering design and analysis of their mechanical harvesting, handling, transporting and processing systems. Agricultural materials, which composed of structural members and fluids do not react in a purely elastic manner, and their response when subjected to stress and strain is a combination of elastic and viscous behavior so called viscoelastic behavior. Many researchers have conducted studies on the mechanical and rheological properties of the various agricultural products, but a few researcher has studied those properties of rice plant, and also those data are available only for foreign varieties of rice plant. This study are conducted to experimentally determine the mechanical and the rheological properties such as axial compressive strength, tensile strength, bending and shear strength, stress relaxation and creep behavior of rice stems, and grain detachment strength. The rheological models for the rice stem were developed from the test data. The shearing characteristics were examined at some different levels of portion, cross-sectional area, moisture content of rice stem and shearing angle. The results obtained from this study were summarized as follows 1. The mechanical properties of the stems of the J aponica types were greater than those of the Indica ${\times}$ Japonica hybrid in compression, tension, bendingand shearing. 2. The mean value of the compressive force was 80.5 N in the Japonica types and 55.5 N in the Indica ${\times}$ Japonica hybrid which was about 70 percent to that of the Japonica types, and then the value increased progressively at the lower portion of the stems generally. 3. The average tensile force was about 226.6 N in the Japonica types and 123.6 N in the Indica ${\times}$ Japonica hybrid which was about 55 percent to that of the Japonica types. 4. The bending moment was $0.19N{\cdot}m$ in the Japonica types and $0.13N{\cdot}m$ in the Indica ${\times}$ Japonica hybrid which was 68 percent to that of the Japonica types and the bending strength was 7.7 MPa in the Japonica types and 6.5 MPa in the Indica ${\times}$ Japonica hybrid respectively. 5. The shearing force was 141.1 N in Jinju, the Japonica type and 101.4 N in Taebaeg, the Indica ${\times}$ Japonica hybrid which was 72 percent to that of Jinju, and the shearing strength of Taebaeg was 63 percent to that of Jinju. 6. The shearing force and the shearing energy along the stem portion in Jinju increased progressively together at the lower portions, meanwhile in Taebaeg the shearing force showed the maximum value at the intermediate portion and the shearing energy was the greatest at the portion of 21 cm from the ground level, and also the shearing strength and the shearing energy per unit cross-sectional area of the stem were the greater values at the intermediate portion than at any other portions. 7. The shearing force and the shearing energy increased with increase of the cross-sectional area of the rice stem and with decrease of the shearing angie from $90^{\circ}$ to $50^{\circ}$. 8. The shearing forces showed the minimum values of 110 N at Jinju and of 60 N at Taebaeg, the shearing energy at the moisture content decreased about 15 percent point from initial moisture content showed value of 50 mJ in Jinju and of 30 mJ in Taebaeg, respectively. 9. The stress relaxation behavior could be described by the generalized Maxwell model and also the compression creep behavior by Burger's model, respectively in the rice stem. 10. With increase of loading rate, the stress relaxation intensity increased, meanwhile the relaxation time and residual stress decreased. 11. In the compression creep test, the logarithmic creep occured at the stress less than 2.0 MPa and the steady-state creep at the stress larger than 2.0 MPa. 12. The stress level had not a significant effect on the relaxation time, while the relaxation intensity and residual stress increased with increase of the stress level. 13. In the compression creep test of the rice stem, the instantaneous elastic modulus of Burger's model showed the range of 60 to 80 MPa and the viscosities of the free dashpot were very large numerical value which was well explained that the rice stem was viscoelastic material. 14. The tensile detachment forces were about 1.7 to 2.3 N in the Japonica types while about 1.0 to 1.3 N in Indica ${\times}$ Japonica hybrid corresponding to 58 percent of Japonica types, and the bending detachment forces were about 0.6 to 1.1 N corresponding to 30 to 50 percent of the tensile detachment forces, and the bending detachment of the Indica ${\times}$ Japonica hybrid was 0.1 to 0.3 N which was 7 to 21 percent of Japonica types. 15. The detachment force of the lower portion was little bigger than that of the upper portion in a penicle and was not significantly affected by the harvesting period from September 28 to October 20. 16. The tensile and bending detachment forces decreased with decrease of the moisture content from 23 to 13 percent (w.b.) by the natural drying, and the decreasing rate of detachment forces along the moisture content was the greater in the bending detachment force than the tensile detachment force.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.33 no.1
• /
• pp.1-12
• /
• 2021

To investigate the effect of freshwater discharge on the seawater circulation in the semi-closed harbor, a 3-D hydrodynamic model was applied to the International Ferry Terminal (IFT). The model run is conducted for 45 days (from May 15 to June 30, 2020), and the reproducibility of the model for time-spatial variability of current velocity and salinity was verified by comparison with model results and observation data. There are two sources of freshwater towards inside of the IFT: Han River and water reservoir located in the eastern part of IFT. In residual current velocity results, the two-layer circulation (the seaward flow near surface and the landward flow near bottom)derived from the horizontal salinity gradient in only considering the discharge from a Han River is more developed than that considering both the Han River and water reservoir. This suggests that the impact of freshwater from the reservoir is greater in the IFT areas than that from a Han River. Additionally, the two-layer circulation is stronger in the IFT located in southern part than Incheon South Port located in northern part. This process is formed by the interaction between tidal current propagating into the port and freshwater discharge from a water reservoir, and flow with a low salinity (near 0 psu) is delivered into the IFT. This low salinity distribution reinforces the horizontal stratification in front of the IFT, and maintains a two-layer circulation. Therefore, local sources of freshwater input are considered to estimate for mass transport process associated with the seawater circulation within the harbor and It is necessary to perform a numerical model according to the real-time freshwater flow rate discharged.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.13 no.1
• /
• pp.56-66
• /
• 2008

Subtidal surface currents are derived from HF radar measurements in the Saemangeum coastal ocean of the Yellow sea in July 2002 and from September to November 2004. The surface current field is analyzed to examine the effect of wind, river plume and coastline change on the spatial distribution and temporal variation of the surface currents. In July 2002, average wind speed was 0.5 m/s and freshwater discharge from the Keum River was $0.88{\times}10^7\;ton/day$. Temporal mean currents ($\overline{U}$) flow to the northwest with speed of $7{\sim}10\;cm/s$ near the Keum River estuary, to the west as fast as 13 cm/s near the opening gap of the Saemangeum $4^{th}$ dyke, and to the northwest off the Gogunsan-archipelago. This flow pattern is a result of the Keum River plume dispersal and tide-residual currents from the opening gap of the Saemangeum $4^{th}$ dyke. Time series of spatially-averaged current (<$U-\overline{U}$>) direction is highly (r=0.98) correlated with wind direction. From September to November 2004, the opening gap of the Saemangeum $4^{th}$ dyke was closed, northwesterly wind blew with speed of 2.5 m/s on average and the Keum River discharge was $1.19{\times}10^7\;ton/day$. Temporal mean current field ($\overline{U}$) has weak surface flow in most of the coastal ocean and relatively strong currents flow to the southwest with speed of 10 cm/s along the shape coastline of the Gogunsan-archipelago and the Saemangeum $4^{th}$ dyke. The strong flow is generated by the prevailing northwesterly wind which pushes the Keum River plume toward the Saemangeum $4^{th}$ dyke. The residual currents from the opening gap of the Saemangeum $4^{th}$ dyke disappeared and correlation coefficient between time series of spatially-averaged current () direction and the wind direction is 0.69.