• Journal of The Korean Society of Grassland and Forage Science
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• v.19 no.1
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• pp.81-88
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• 1999

A field experiment with 200, 400 and $600kg{\cdot}N/ha/year$ application levels was carried out to study the nitrate nitrogen accumulation and forage yield of sorghum sudangrass hybrid(Xtragraze II) at Iksan College Farm in 1995. The nitrate nitrogen contents were increased by the application of nitrogen and decreased as the plant matured, then the accumulation of nitrate nitrogen started from 200kg application, and exceeded the safe level of ruminants at the level of 400kg application during the whole growing period. In the early stage of growth, nitrate nitrogen contents of sorghum sudangrass hybrid were increased by rainfall during the dry season, but these contents are almost kept constantly at the low level in the later stage of growth. Accumulation of nitrate nitrogen in the morning had a greater tendency than that of the afternoon. A sum exceeding $200kg{\cdot}N$ does not necessarily result in increase the amount of nitrate nitrogen in sorghum sudangrass hybrid.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.26 no.3
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• pp.257-262
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• 1981

Field experiment with 0, 100, 200, 400, and 800 kg-N/ha-year application levels was carried out to study the nitrogen response in the early stage of orchardgrass pasture establishment at College Fann, SNU, in 1979 and 1980. Both the highest dry matter yield and maximum percent of N recovery were obtained at the same level of 200 kg-N/ha in the year of seeding. but those of the next year were obtained at 400 kg-N/ha level. Leaf area indices (LAI) and net assimilation rates (NAR) during each regrowth periods as well as total nitrogen contents of forage at each cutting time increased with applied N in both years. The maximum crop growth rate (CGR) over two years was estimated to be obtained when LAI reached to about 5. The accumulation of NO_3 -N in forage started from 400kgㆍN/ha application in 1980. and exceeded the safe level for ruminants at the level of 800 kg-N/ha.

• Research in Plant Disease
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• v.12 no.3
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• pp.294-297
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• 2006

Leafy lettuce(Lactuca sativa L.) is one of the most important vegetable crops in Korea, cultivated throughout the year in greenhouses. During the autumn of 2005, powdery mildew of lettuce that is a new disease caused by Podosphaera fusca occurred in several plantings grown in plastic houses near Suwon in central Korea. Further survey on commercial fields of the plant in central and southern Korea revealed its widespread occurrence and severe losses. Infections occur on upper part of mature leaves often cause leaf distortions, withering, and reduced vigor and growth. Among 184 greenhouses surveyed 121 were infested by the disease and 52 showed over 10% infection rate. Yields were greatly reduced by the disease reaching only 59% compared to healthy plants. About 60% leaves of infected plant were not marketable and fresh weight of the leaves was 73.6% compared to healthy leaves. Total yield of the greenhouses infested by the disease ranged from $100{\sim}140kg$, while it was 260 kg in a non-infested greenhouse at one time harvest. Since the disease represents a threat to safe cultivation of leafy lettuce in Korea, environmentally-friend control strategies should be urgently developed.

• Geomechanics and Engineering
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• v.20 no.1
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• pp.1-7
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• 2020

In structures excavated in rock mass, load progressively increases to a level and remains constant during the construction. Rocks display different elastic properties such as E_i and ʋ under different loading conditions and this requires to use the true values of elastic properties for the design of safe structures in rock. Also, rocks will undergo horizontal and vertical deformations depending on the amount of load applied. However, under constant loads, values of E_i and ʋ will vary in time and induce variations in the behavior of the rock mass. In some empirical equations in which deformation modulus of the rock mass is taken into consideration, elastic parameters of intact rock become functions in the equation. Hence, the use of time dependent elastic properties determined under constant loading will yield more reliable results than when only constant elastic properties are used. As well known, rock material will play an important role in the deformation mechanism since the discontinuities will be closed due to the load. In this study, E_i and ʋ values of intact rocks were investigated under different constant loads for certain rocks with high deformation capabilities. The results indicated significant time dependent variations in elastic properties under constant loading conditions. E_i value obtained from deformability test was found to be higher than the E_i value obtained from the constant loading test. This implies that when static values of elastic properties are used, the material is defined as more elastic than the rock material itself. In fact, E_i and ʋ values embedded in empirical equations are not static. Hence, this workattempts to emerge a new understanding in designing of safer structures in rock mass by numerical methods. The use of time-dependent values of E_i and ʋ under different constant loads will yield more accurate results in numerical modeling analysis.

• Journal of The Korean Society of Grassland and Forage Science
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• v.14 no.2
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• pp.76-81
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• 1994

This experiment was carried out to select the best adaptable varieties of Tall fescue in mountainous pastures of Taekwalyon area. The evaluation was based on the data of varietial differences in the dry weight of plant@W) and yield components of the 2nd growth. Nine varieties of Tall fescue examined were Barcel, Barvetia, Demeter, Enforcer, Forager, Fuego, Johnstone, Safe and Stef. And, the final cutting times were Sept. 30 ($C_1$), Oct.14 ($C_2$),Oct. 28 ($C_3$), and Nov. 11($C_4$). The reults were summarized as follows: 1. Barcel and Forager with many tillers per plant(NT) showed a high dry weight of plant@W) of the 2nd growth. 2. The dry weight of plant(DW) of the 2nd growth indicated significantly positive correlation with the number of tillers per plant(NT), but there was not significant correlation with the dry weight of tiller(WT). 3. The maximum dry weight of plant@W) of the 2nd growth was obtained at $C_3$(28 Oct.). 4. The dry weight of the 2nd growth showed an inverse relations with the dry weight of the 1st growth as affected by various final cutting time in growth period of autumn.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.6
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• pp.84-91
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• 2002

Temperature distribution in the GTD111 turbine blade used in power plaints is calculated by heat transfer analysis. Linear stress analysis of the turbine blade is also carried out under thermal loads and centrifugal forces. The numerical results of steady state heat transfer analysis slow that high temperature distribution occurs at the leading edge and tip section of the blade. The thermal stress result indicates that the equivalent stress at the tip of the pressure surface is higher than other sections of the blade. Maximum centrifugal stresses without the thermal effect occurs at the front of the fir tree. From the thermal-centrifugal stress analysis, maximum equivalent stress occurs at the fir tree. Stresses applied by the thermal loads and centrifugal forces are less than the yield stress. The GTD111 turbine blade is safe to be used in the power plants.

• Journal of The Korean Society of Grassland and Forage Science
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• v.13 no.3
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• pp.203-212
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• 1993

This experiments were carried out to estimate the optimum final cutting date in autumn and the selection of highly adaptable varieties in mountainous pastures of Taekwalyong area. The evaluations were based on the data of varietal differences of dry weight of plant(DW) and yield components of the 1st cutting as affected by various final cutting dates of last autumn. Nine varieties of tall fescue Barvetia, Fuego. Demeter, Safe. Barcel, Forager, Johnstone, Enforcer and Stef. were used and 4 final cutting date of autumn were $C_1$, cut on 30 Sept. $C_2$, on 14 Oct. $C_3$, on 28 Oct. and $C_4$. on 11 Nov.. respectively. The results obtained were as follows: I . Between the dry weight of plant(DM) and yield components of 1st cutting were different by various final cutting dates of autumn. The dry weight of plant(DW) was significantly positive correlated with heading characteristics of the 1st cutting in earlier cuttings($C_1- C_3$) of autumn, but there was not significant correlated with heading characteristics of the 1st cutting in the latest cutting($C_4$) of autumn. 2. The variety of Forager with heavier weight of heading tiller(HTW) and dry weight of tiller(WT) showed the highest dry weight of plant(DW) of the 1st cutting in earlier cuttings($C_1-C_3$) of autumn, whereas the variety of Barcel with high number of tillers per plant(NT) showed a high dry weight of plant(DW) of the 1st cutting in the latest cutting($C_4$) of autumn. 3. Optimum final cutting date and critical period of mountainous pastures in Taekwalyong area were estimated in late September($C_1$) and middle October($C_2$), sespectirety. 4. The dry weight of plant(DW) of the 1st cutting was significantly negative correlated with final cutting dates in growth period of autumn.

• Journal of Convergence for Information Technology
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• v.10 no.11
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• pp.177-184
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• 2020

The objective of this study was to investigate the effect of cold-pressed flaxseed oil through the roasting temperature (unroasted and roasted at 150℃ and 200℃) and time (10 and 20 min) on the chemical changes. Cold-pressed flaxseed oil extraction yield was calculated with respect to the roasted process and total phenolic content, fatty acid composition, and volatile compound were analyzed. The extraction yield was increased in the roasted oil compared to the unroasted oil. Total phenolic content was significantly higher in oil from the roasted at 150℃ for 20 min compared to other roasting condition. Fatty acid composition was not affected by the extraction process. The content of aldehyde, ketone, furan, and pyrazine was higher than in the roasted at 200℃ compared to the unroasted and roasted at 150℃. These findings suggest that cold-pressed flaxseed oil extracted from the roasted at 150℃ for 20 min may be considered acceptable for safe extraction process.

• Journal of the Korean Institute of Gas
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• v.11 no.2 s.35
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• pp.55-59
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• 2007

This paper presents the strength safety of a LPG cylinder, which is fabricated by a steel sheet forming and a welding technology. The strength safety of a cylinder is guaranteed by analyzing a stress distribution of a LPG cylinder structure using a finite element method. The FEM computed results indicate that the hydraulic test gas pressure of $31kg/cm^2$ generates a concentrated local stress near the upper round end plate, which exceeds the yield strength of a LPG cylinder. Thus, the current hydraulic test pressure may be rechecked and revised because this pressure increases the fatigue failure and decreases the lift of the pressure vessel. The normal operation and sealing gas pressures such as $9kg/cm^2\;and\;18.6kg/cm^2$ are relatively safe for a steel LPG cylinder.

• Journal of Chest Surgery
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• v.56 no.5
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• pp.336-345
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• 2023

Background: The objective of this study was to demonstrate the safety, efficacy, and feasibility of intraoperative monitoring of the recurrent laryngeal nerves during thoracoscopic and robotic 3-field esophagectomy. Methods: This retrospective analysis details our initial experience using intraoperative nerve monitoring (IONM) during minimally invasive 3-field esophagectomy. Data were obtained from a prospectively maintained database and electronic medical records. The study included all patients who underwent minimally invasive (video-assisted thoracic surgery/robotic) transthoracic esophagectomy with neck anastomosis. The patients were divided into those who underwent IONM during the study period and a historical cohort who underwent 3-field esophagectomy without IONM at the same institution. Appropriate statistical tests were used to compare the 2 groups. Results: Twenty-four patients underwent nerve monitoring during minimally invasive 3-field esophagectomy. Of these, 15 patients underwent thoraco-laparoscopic operation, while 9 received a robot-assisted procedure. In the immediate postoperative period, 8 of 24 patients (33.3%) experienced vocal cord paralysis. Relative to a historical cohort from the same institution, who were treated with surgery without nerve monitoring in the preceding 5 years, a 26% reduction was observed in the nerve paralysis rate (p=0.08). On follow-up, 6 of the 8 patients with vocal cord paralysis reported a return to normal vocal function. Additionally, patients who underwent IONM exhibited a higher nodal yield and a decreased frequency of tracheostomy and bronchoscopy. Conclusion: The use of IONM during minimally invasive 3-field esophagectomy is safe and feasible. This technique has the potential to decrease the incidence of recurrent nerve palsy and increase nodal yield.