• Research in Plant Disease
• /
• v.8 no.4
• /
• pp.199-206
• /
• 2002

It was investigated on the relationship of the rice blast epidemics and the real-time meteorological factors, at the experimental paddy field in 1997. Weather factors(temperature, relative humidity, irradiation, precipitation, the direction of wind, wind speed, soil temperature and leaf-wetness, etc) were measured by using the automated weather station. The most influenced weather factor to blast epidemics, was the average max-temp($R^2$= 0.95) during 10 days before leaf blast epidemics, while the least thing was wind speed($R^2$= 0.24). The most potential weather factors correlated with the blast epidemics were T-ave(average temperature), T-max(maximum temperature), RH(Relative Humidity) and RD(Relative Humidity > 90% hrs). A statistics model(the regression equation) of the blast epidemics with the potential weather factors, was established as tallows ; Y = -3410.91 - 23.91 $\times$ T-ave ＋ 28.56 $\times$ T-max ＋ 41.0 $\times$ RH - 3.75 $\times$ RD, ($R^2$= 0.99). (T-ave >= 19$^{\circ}C$, T-max - T-ave >= 5.2$^{\circ}C$ and RH% >= 90.4%). According to the fitness test($\chi$$^2$) of the model, the observed blast disease severity was quite close to those expected.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.24 no.1
• /
• pp.1-8
• /
• 1991

Population dynamics of Matted sole Limanda yokohamae($G{\"{U}}NTHER$) in Tokyo bay, Japan has been studied by virtual population analysis (VPA) for multi cohort and experimental fishing. Based on the biological data, the present parameters of the Limanda yekohamae stock at the Tokyo bay, Japan were estimated as follows: natural mortality coefficient(M) were 0.313 for male and 0.250 for female, terminal fishing mortality coefficient(F) were 2.190 for male, and 0.798 for female, rate of exploitation(E) was $30\%\;to\;50\%$. From the result of virtual population analysis for multi cohort, the population size were estimated from 3,5000,000 to 9,200,000 fishes, according to the result of experimental fishing, estimated stock size were 2,400,000 to 8,700,000 fishes. Stock size difference of the two methods were about two times in 1987, however, other years has been showed from 0.8 to 1.5 times. Both method has been showed same increase and decrease tendency of the c. p. u. e. and catches. From the isopleth diagram plot by Beverton and Holt's yield per recruit, the catches could be increase two times for female, 1.3 times for male than present aspects by the fishing management. And further, as reducing fishing effort, extension of mesh size and rising the length at first caputre, are reasonable in order to manage the stock at the optimum level.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.10
• /
• pp.174-180
• /
• 2020

This paper presents the development of a tacho generator that is applicable to a DC motor for anti-aircraft weapon systems. In general, devices such as tacho generators and resolvers are used as feedback devices for controlling DC motors. A tacho generator with a wide operating temperature range was developed, which has robust characteristics against shock loads and vibrations according to the operational characteristics of anti-aircraft weapon systems. The target specifications were set based on the requirements of the tacho generator currently in operation. A rotor coupled to the shaft of the motor and a stator coupled to the housing of the motor were then designed and manufactured. The inductance was 31.0 mH, the terminal resistance was 147.7 ohms, and the rotational measurement factor was satisfactory under both normal operation and operating conditions after the maximum speed for the standard of 9.500 ± 0.475 V/krpm. In addition, the environmental suitability of the applied equipment was confirmed through the rate of change in unit temperature, and it was found that the temperature characteristics were all within 0.03 %/℃.

• Journal of Korean Society of Forest Science
• /
• v.87 no.2
• /
• pp.286-299
• /
• 1998

This study was conducted to do a comparative analysis of hunting system in 16 OECD(Organization for Economic Co-operation and Development) countries. Hunting is one of the most advanced types for developing natural resources, esp. wildlife, which is one of major products from forest. There are two types of hunting system ; Revier and/or License System, around most countries which have traditional advanced hunting and higher hunter population. Licence system, which is chosen in Korea, is less efficient ways of hunting for maximizing economical value and wildlife management than Revier system does. Adopting better system for much more efficient economical condition from hunting in Korea in a future is a ultimate goal in this study. The first step for the goal is an analysis of these two system among 16 OECD countries ; United State, Japan, Germany, France, etc. Comparative researches in hunting regulations such as number of hunters, hunter ratio to population, hunting bags, game species, seasons, ammunition and hunting permit are a next step for adopting developed hunting system in Korea. Korea has a smallest hunter ratio to population (1/2,463) among 16 OECD centuries and economical value lead by hunting is estimated still very low. Revier system is a popular one in most OECD countries except United State, Japan, etc, which is useful for wildlife management and maximizing economical value of hunting. And usually rifles are permitted for big game hunting. Hunting examination and/or insurance are compulsory for achieving hunting permit. Depend on game species, yearly hunting bag and season are constructed in most OECD countries.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.18 no.12
• /
• pp.762-767
• /
• 2017

This paper presents an analysis for improving the power transfer capability in transmission lines caused by the movable load charging of electric vehicles (EVs). EVs are expected to be used more widely and replace gas fuel vehicles in the near future due to the shortage of fossil fuels and for environmental preservation. Movable load charging of EVs could lead to the convergence of transferred power flow and overloading conditions in transmission lines in a specific area of a power system, which is conventionally based on estimated fixed load capability. To analyze these conditions, the New England Test System was divided into four regions based on the load characteristics, and different charging scenarios were considered. In these scenarios, the regional power load was highly increased to 31% based on the standard charging capacity of an EV. As a solution to the overloading problem of transmission lines, a TCSC was installed serially on the overloaded line to directly control the transferred power under limited line capability (100% load capability). The simulation showed that the application of a few TCSCs could efficiently and economically control the line capability problem caused by movable load charging of EVs.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.14
• /
• pp.111-115
• /
• 1973

This experiment was carried out to study the effects of planting density and amount of fertilizer applied on the morphological, physiological and physical characteristics of barley culm. The results are summarized as follows: 1. Heavy application of fertilizer increased the diameter of the inside and outside thickness of culm, dry weight per unit culm, culm length, spike weight and number of per hill. 2. Thined planting density increased lodging resistance. But lodging resistance in sparse-planted plot of$20{\times}$ 20cm was almost the same as that in the plot of $15{\times}$ 15cm. 3. In the heavy fertilized plot weight of culm at breaking, bending moment of culm atbreaking, secondary moment of inertia and section modulus increased more than those in the standard fertilized one. As a result heavy application of fertilizer gave high lodging resistance. On the other hand thined planting density increased the above-mentioned physical characters of culm. 4. In the case of dense planting lodging index became higher in standard fertilized plot, but in the case of sparse planting over 10 x 10cm there were no significant differences in lodging index as affected by amount of fertilizer applied and planting density. 5. Grain yield was increased by heavy application of fertilizer and proper planting density was $5{\times}$ 5cm or $10{\times}$10cm for the safe maximum yield.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.14
• /
• pp.117-121
• /
• 1973

This experiment was conducted to study the effects of nitrogen top-dressed at the different growth stages on the morphological and physical characteristics of barley culm. The results obtained are summarized as follows: 1. By top-dressing of nitrogen in March, each internode length from the third to the fifth internode was shortened, and total fresh weight of the top, dry weight per unit culm, inside or outside culm diameter and thickness of culm were increased. Therefore these characteristics related to lodging indicated the beneficial changes for lodging resistance by top-dressing of nitrogen in March. 2. Both weight of culm at breaking and bending moment of culm at breaking, expressing lodging resistance of culm, were increased in the plots of nitrogen top-dressed in March. Accordingly lodging resistance became higher by top-dressing of nitrogen in March. 3. Both section modulus and secondary moment of inertia, expressing bending stiffness of culm, were increased by top-dressing of nitrogen in March. Accordingly lodging index, expressing comprehensive lodging resistance, became low by top-dressing of nitrogen in March. 4. Both spike weight and grain yield were increased by top-dressing of nitrogen in March. Consequently we came to the conclusion that the suitable top-dressing time of nitrogen was in March.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.19 no.2
• /
• pp.137-143
• /
• 2016

The sedimentary environment and sediment were surveyed at the West-Northern site of Chagwi-do nearby Jeju Island for the design of the embedded suction anchor system of 10 MW-class floating wave-offshore wind hybrid power generation system. According to the classification scheme of Chough et al.[2002], the echo type of the seismic profiles using the chirp III was classified. As a results, the center and west-northern area of survey site were proved to be type I-3 where subbottom layer with thickness 5~15 m exists under the flat seafloor. On the other hands, the east-southern area were regarded to be type I-1, I-2 and III-1 where seafloor reflection is much stronger than type I-3. Also, the physical tests (unit weight, moisture content, grain size, liquid limit, specific gravity) were performed with samples taken from 8 fixed locations. It is found that the sand (SP), the sand blended with silt (SM) and the mixture of SP-SM are distributed uniformly on the survey area.

• The Journal of Engineering Geology
• /
• v.20 no.1
• /
• pp.35-45
• /
• 2010

The soil tests have been performed on the specimens obtained from about 1,150 sites including landslides and non-landslides areas in natural terrains for last 10 years. Based on the results of those tests, the average soil properties are estimated and the simple equations for estimating permeability are proposed according to geologic conditions. The average permeability in Granite and Mudstone sites is higher than other sites and the content of silt and clay in Mudstone and Gneiss sites is higher than other sites. The correlation analysis and the regression analysis were performed to estimate the coefficient of permeability according to geological conditions. As the result of the correlation analysis, the coefficient of permeability is selected as a dependent variable, and the silt and clay contents, the water contents and the dry unit weights are selected as independent variables. As the result of the regression analysis, the silt and clay contents and the void ratio were involved commonly in the linear regression equations according to geological conditions. To verify the proposed the linear regression equations, the measured result of the coefficient of permeability at other sites was compared with the result predicted with the proposed equations. As the result of comparison, there were a little bit different between them for some data. However the difference was relatively small. Therefore, the linear regression equations for estimating the coefficient of permeability according to geological conditions may be applied to Korean soils. However, these equations should be verified and corrected continuously to improve the accuracy.

• Journal of the Korean Wood Science and Technology
• /
• v.12 no.4
• /
• pp.12-18
• /
• 1984

Soaking treated in 20% aqueous solutions of $(NH_4)_2SO_4$, $NH_4H_2PO_4$, $(NH_4)_2HPO_4$, $Na_2B_4O_7-H_3BO_3$(60:40) and Minalith, the mixed salts for 9 hrs. the wet 3.5mm meranti (Parashorea spp.) plywoods were press-dried at 90, 120 and $150^{\circ}C$ and put to static bending test to examine the influence of redrying temperature on the strength of fire-retardant treated plywoods ill flexure. While water-soaking treatment (control) showed serious reduction in Stress at proportional limit, MOE, MOR, Work per unit volume at $150^{\circ}C$, all the fire-retardant treatments maintained bending strength even at $150^{\circ}C$ and showed rather increased values in case of some chemicals. In view of drying rate and maintenance of strength, the most pertinent platen temperature was $150^{\circ}C$ and Borax-Boric acid was the predominant fire-retardant in this study.