• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.363-363
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• 2017

The NPK are known as macro elements that affect crop growth and yield. In 1989, Cambodia Agricultural Research and Development Institute (CARDI) gave a recommendation rate of fertilizer on rice production based on soil types. This recommended rate of NPK seems however relatively low as compared to farmers' practices nowadays and the amount in the neighboring countries. The CARDI recommended rate for Prateah Lang soil type is 50kg N, 25kg P2O5, 25kg K2O ha-1 while recent farmers' practice rates are 55 - 64kg N, 24 - 46kg P2O5, 30kg K2O ha-1. However, the overuse of chemical fertilizer will lead to un-preferable plant growth, insect pest, disease and economic yield. Thus, we examined the effect of different NPK application rates on the growth and yield components in Prateah Lang soil type in Takeo province to investigate appropriate rates for improving rice productivity with economic efficiency. This study was conducted from July to November during wet season in 2013. A multi-locational trial with 6 treatments (T0 - T5) of NPK rates in 5 locations (trial 1 - 5) with 3 replications was conducted. The different combinations of NPK application were employed from 0, 50, 60, 80, 100, 120kg N ha-1, 0, 25, 30 45, 60kg P2O5 ha-1 and 0, 15, 25, 30, 45kg K2O ha-1. Urea, DAP and KCl were used for fertilization. Split application was employed [basal: 20% of N, 100% of P and K, top dressing-1st: 40% of N (30DAT), 2nd: 40% of N (PI stage)]. Three-week-old seedlings of var. Phka Rumdoul were transplanted with 2 - 3 seedlings hill-1 with $20cm{\times}20cm$ spacing. Plant length, tiller number at the maximum tillering stage and yield components were measured. The different rates of NPK application affected some yield components. The panicle number per hill was the most important key component followed by the spikelet number per panicle. However, the other parameters such as the filled grain percentage and 1000 grains weight had small effect or weak relation with the yield. Although the panicle number per hill had a significantly positive correlation with the stem number per hill, it was not correlated with the percentage of productive culms. The variation in the grain yield among the 5 trials was small and the difference was not significant. Although the yield tended to be higher at higher N and P application, there was no significant difference above 60kg N and 30kg P2O5. The yield was the highest at 15, 30 and 45kg K2O followed by 25kg K2O. The relationships between N, P and the stem number per hill were significantly linear positive, though it was not linear between K and the stem number. From these results, to increase rice productivity in the target area, farmers' effort to increase N and P input rather than CARDI recommendation up to 60kg N and 30kg P2O5 will be sufficient considering economic efficiency. Besides, the amount of K application should be reconsidered.

• Journal of the Korean Society of Safety
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• v.14 no.1
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• pp.208-215
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• 1999

The creep behavior of a rapidly solidified and consolidated Al-9.45wt%Fe-4.45wt%Cr alloy were investigated in the stress range 40 to 115 MPa and temperature range 300(0.53Tm) to 441$^{\circ}C$(0.66Tm). It is of use to available aerospace and automobile industries for the improved performance of materials used at high temperature. Because Al alloys with improved creep resistance offer the potential for lower weight and reduced costs in aerospace and automobile components (e.g., structural members and engine parts) through the replacement of heavier and more costly materials, the safety in use at high temperature is good. The alloy is characterized by high stress exponents and activation energies for creep, which are greatly dependent on the stress and temperature. Because the creep stress is seen to cause a strongly significant enhancement of coarsening, the coarsening rate of the dispersed particles in all crept specimens is faster than that in isothermally annealed specimens. Dislocations connecting dispersoids are observed more cofrequently in crept specimens with higher stress and lower temperature. The creep strain rates in the power law creep regime were found to be predicted much better by the Shorty and Rosler/Arzt equation with the inclusion of a threshold stress and dislocation detachment mechanism. The dispersoids in this alloy were acting a source of void nucleation that finally leaded to ductile fracture within the grain so called intergranular. Each void was initiated, grown and failed at the dispersoids in the aluminium matrix. Grain boundary accommodation of the slip produced, which result in initiation of the void and then final transgranular fracture. Therefore, it was confirmed that these dispersoids played an important role in the fracture mechanism by the formation of $Al_{13}Fe_4$, $Al_{13}Cr_2$ and $Al_2O_3$.

• Progress in Superconductivity and Cryogenics
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• v.16 no.4
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• pp.21-25
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• 2014

In order to develop 2nd generation (2G) high-temperature superconducting (HTS) wires as commercial products, it is necessary to perform a high speed investigation of their superconducting performance. Room-temperature and non-contact optical scanning tools are necessary to verify the microstructure of the superconducting materials, the current flow below the critical temperature, and the critical current density. In this paper, we report our results of an inspection of the electrical transport properties of coated conductors. The samples that we used in our study were highly qualified rare-earth based coated conductors produced via co-evaporation, and $SmBa_2Cu_3O_{7-y}$ (SmBCO) was the superconducting materials used in our studies. A film grown on IBAD-MgO templates shows larger than 400 A/cm at 77 K and a self-field. The local transport properties of the films were investigated by room-temperature imaging by thermal heating. The room-temperature images show structural inhomogeneities on the surface of the films. Bolometric response imaging via low-temperature bolometric microscopy was used to construct the local current mapping at the surface. These results indicate that the non-uniform regions on the surface disturb the current flow, and laser scanning images at room-temperature and at a low-temperature suggest a correlation between the structural properties and transport properties. Thus this method can be effective to evaluate the quality of the coated conductors.

• YAKHAK HOEJI
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• v.29 no.1
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• pp.32-38
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• 1985

The anthelmintic substance of the roasted fruits of Prunas mume against Clonorchis sinensis was isolated and its structure was identified by chemical and physical methods. The results obtained from the experiments are as follows: 1) The methanol extract of the roasted fruits of P. mume was fractionated into four parts: petroleum ether, ethyl ether, ethyl acetate and water soluble part. Among these, etherial fraction was found to have strong wormicidal effect on liberated metacercaria of Clonorchis sinensis. 2) From the etherial fraction, the wormicidal substance was isolated by silica gel, polyamide and sephadex column chromatography and identified to be 5-hydroxymethylfurfural (5-HMF) by chemical and spectral data. 3) 5-HMF was synthesized and administered to the rabbits infected with C. sinensis. On the 2nd day after administration, the EPG (eggs per gram in feces) reached to the maximal value. Among the adult worms isolated from the bile duct of the treated animal, 84% of worms were damaged morphologically. 4) The content of 5-HMF in the fruits of P. mume which were roasted in an oven at $90-110^{\circ}C$ for 52 hours and that in the fresh fruits was evaluated by HPLC. The content of 5-HMF was 0.8% in the roasted fruits and 0.02% in the fresh ones.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.1071-1074
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• 2008

In this study, the behavior of dredged soil was measured by repeated tide and analyzed the change of settlements and cone penetration resistance by centrifuge model about dredged soil of Kunsan-Janghang site that maximum tidal range is 7.4m. Consequently the settlements of dredged soil by repeated tide in the 2nd month was 0.489 m. After 12th month, the total settlements was 0.524 m in the model. It meaned the settlements of dredged soil by repeated tide in the 2th month was 80% of the settlements. Also, with the lapse of time, cone penetration resistance increased centrifuge model test for catching the strength change of dredged soil by repeated tide. After 10th month, there were not almost changes. cone penetration resistance in 10th month was measured more 3.5~5.6 times than that in its early stages. Also, with the lapse of time, cone penetration resistance increased almost linearly. And, when we surveyed the relation between cone penetration resistance and time, as depth increased, cone penetration resistance rose.

• Current Optics and Photonics
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• v.1 no.4
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• pp.402-411
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• 2017

Combined LIBS-Raman spectroscopy has been widely studied, due to its complementary capabilities as an elemental analyzer that can acquire signals of atoms, ions, and molecules. In this study, the classification of polymorphs was performed by laser-induced breakdown spectroscopy (LIBS) to overcome the limitation in molecular analysis; the results were verified by Raman spectroscopy. LIBS signals of the $CaCO_3$ polymorphs calcite and aragonite, and $CaSO_4{\cdot}2H_2O$ (gypsum) and $CaSO_4$ (anhydrite), were acquired using a Nd:YAG laser (532 nm, 6 ns). While the molecular study was performed using Raman spectroscopy, LIBS could also provide sufficient key data for classifying samples containing different molecular densities and structures, using the peculiar signal ratio of $5s{\rightarrow}4p$ for the orbital transition of two polymorphs that contain Ca. The basic principle was analyzed by electronic motion in plasma and electronic transition in atoms or ions. The key factors for the classification of polymorphs were the different electron quantities in the unit-cell volume of each sample, and the selection rule in electric-dipole transitions. The present work has extended the capabilities of LIBS in molecular analysis, as well as in atomic and ionic analysis.

• Journal of Electrical Engineering and Technology
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• v.13 no.3
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• pp.1166-1172
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• 2018

Degradation due to delamination occurs frequently in the high temperature superconductors (HTS) coil of rotating machines made with 2nd generation (2G) HTS wire, and the authors have observed other similar cases. Since an HTS field coil for a rotating machine is required to have stable current control and maintain a steady state, co-winding techniques for insulation material and epoxy resin for shape retention and heat transfer improvement are applied during coil fabrication. However, the most important limiting factor of this technique is delamination, which is known to be caused by the difference in thermal expansion between the epoxy resin and 2G HTS wire. Therefore, in this study, the experimental results of mixing the ratio of epoxy resin and alumina ($Al_2O3$) filler were applied to the fabrication of small and large test coils to solve the problem of degradation. For the verification of this scheme, eight prototypes of single pancake coils with different shapes were fabricated. They showed good results. The energization and operation maintenance tests of the stacked coils were carried out under liquid neon conditions similar to the operation temperature of an MW-class rotating machine. In conclusion, it was confirmed that the alumina powder mixed with epoxy resin in an appropriate ratio is an effective solution of de-lamination problem of 2G HTS coil.

• Journal of The Korean Society of Grassland and Forage Science
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• v.14 no.4
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• pp.257-263
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• 1994

The experiment was canied out to investigate the effects of cutting frequencies (3, 4 and 5 cuts per year) in relation to fertilization of mineral nitrogen on crude protein yield and the contents of crude protein and acid detergent fibre in orchardgms(Dacty1is glomerata L.). Tne results are as follows : 1. The content of crude protein increased according to the increase in cutting frequency and showed the highest in the 1st cut in all treatments. At 4 and 5 cutting frequencies per year, the content of crude protein increased in a large extent according to the increased fertilization of mineral nitrogen. However at 3 cutting frequency, the content of cmde protein appeared higher for no application of mineral nitrogen than for the treatments with fertilization. 2. 'Ihe content of acid detergent fibre(ADF) was considerably reduced at 4 and 5 cutting frequencies and in all treatments, the lowest were recorded in the 1st cut or in the last cut. At 3, 4 and 5 cutting frequencies, the highest ADF were shown in the 2nd cut, 3rd cut and 3rd cut respectively. However, the general trend was that the content of ADF was greatly reduced according to increased level of mineral nitrogen fertilization. 3. The yeild of cmde protein was the highest at 5 cutting frequency(l.2 ton DMIha) and it indicated that the yield of cmde protein increased in accordance to the increase in fertilization of mineral nitrogen and cutting frequency. 4. In all treatments, positive correlation(p<0.001) between the yeilds of crude protein and annual dry matter yield appeared. Negative correIation(p

• Journal of the Korean Society of School Health
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• v.23 no.2
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• pp.246-255
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• 2010

Purpose: This study is based on an experimental research program designed to evaluate the before and after states of a control group that undertook a series of smoking prevention education sessions. Methods: The research was undertaken between June 2 and July 22, 2008. Students from two public elementary schools in Uiwang City took part in the study. 76 students from one of the schools (School 'W') were designated as the experimental group and 89 students from the other school (School 'O') were allotted to the control group. During the research period, the experimental group held 10, 40 minute discussions on the subject of smoking prevention. The control group had no such sessions and no information was given. The data was collected in 3 stages, firstly after initial study preparation, secondly after five sessions and thirdly after ten sessions. The data was analysed using the SPSS/WIN 12.0 program. Results: First, there was a presumption that the experiment group would have a greater knowledge about the effects of smoking than the control group. This was supported by the data analysis results (F=41.79, p =.000). Second it was presumed that the experiment group would have a more informed attitude to smoking than the control group. This was supported by the data analysis results (F=6.917, p =.009). Third, there was the presumption that the experiment group would have a greater knowledge of the effects of smoking after ten sessions than they would five sessions. This was supported by the data analysis results (F=56.911, p =.000, Scheffe=3rd> 2nd>1st). Fourth, the presumption held that the experimental group would have a more informed attitude to the effects of smoking after ten sessions than they did five. This was supported by the data analysis results (F=14.607, p =000, Scheffe=3rd>2nd>1st). Conclusion: The results appear to show that the elementary school students who participated in the smoking prevention sessions had an increased knowledge of the risks and had also formed a more negative attitude towards smoking. On the basis of the findings of this study, I would suggest that there are benefits in developing learner-centered smoking prevention programs and other related media. Also, smoking prevention discussions should be included in the regular curricula relating to health education.

• Economic and Environmental Geology
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• v.55 no.4
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• pp.317-338
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• 2022

Physicochemical characteristics and evaluation were studied by subdividing the concretes, bricks and earth pipes on the site of the Japanese Ministry of General Affairs in Joseon Dynasty, known as modern architecture, into three periods. Concretes showed similar specific gravity and absorption ratio, and large amounts of aggregates, quartz, feldspar, calcite and portlandite were detected. Porosity of the 1907 bricks were higher than those of 1910 and 1950 bricks. All earthen pipe is similar, but the earlier one was found to be more dense. Bricks and earthen pipes are dark red to brown in color within many cracks and pores, but the matrix of the earthen pipe is relatively homogeneous. Quartz, feldspar and hematite are detected in bricks, and mullite is confirmed with quartz and feldspar in earthen pipes, so it is interpreted that the materials have a firing temperature about 1,000 to 1,100℃. Concretes showed similar CaO content, but brick and earthen pipe had low SiO₂ and high Al₂O₃ in the 1907 specimen. However, the materials have high genetic homogeneity based on similar geochemical behaviors. Ultrasonic velocity and rebound hardness of the concrete foundation differed due to the residual state, but indicated relatively weak physical properties. Converting the unconfined compressive strength, the 1st extended area had the highest mean values of 45.30 and 46.33 kgf/cm², and the 2nd extended area showed the lowest mean values (20.05 and 24.76 kgf/cm²). In particular, the low CaO content and absorption ratio, the higher ultrasonic velocity and rebound hardness. It seems that the concrete used in the constructions of the Japanese Ministry of General Affairs in Joseon Dynasty had similar mixing characteristics and relatively constant specifications for each year. It is interpreted that the bricks and earthen pipes were through a similar manufacturing process using almost the same raw materials.