• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.11 no.2
• /
• pp.250-261
• /
• 1999

Based on a set of performance plots relating the design variables to the imposed conditions, an easy-to-use and versatile design procedure for chevron-type multipass plate heat exchangers is developed. In order for the present procedure to cover multipass with unequal passes and non-unity ratio of heat capacity rate, each stream number of transfer unit is adopted as the basic design variable instead of the exchanger number of transfer unit. It is found that there exists a unique relation between the stream and exchanger number of transfer units regardless of the chevron angle and the plate length. In addition, for a given value of the pressure drop the heat transfer area per unit mass flow rate can be expressed in terms of the stream number of transfer unit only. These two relationships in the form of simple plots constitute the framework of design. The sample results in comparison with the available data indicate that the present procedure includes the previous ones as a subset, and that every design method is affected essentially by the selection of specific correlations for the heat transfer coefficient and the friction factor.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.8 no.2
• /
• pp.1193-1199
• /
• 1966

More stable and higher yields in rice paddy depend mainly upon an adequately balanced supply of water for higher yield. Rice paddy is supplied naturally by rainfall but inevitably requires artificial supplenental irrigation for higher yields. Even though it may be true that the water requirement of rice plants is generally higher than those of other crops, the submerged condition is not necessarily required for rice. The moisture requirements of rice vary according to its growing stages and it is possible to increse the irrigation efficiency by means of lessening the loss due to percolation and evapolation in the field. This experiment was conducted on the effect of the various amount of water supply and different irrigation periods for yield and yield components, and was carried out to find out the most suitable irrigation method and to increase the irrigation efficiency for higher yields in rice paddy. Randomized block design with 3 replications was employed where the 3 levels of the amount of irrigation water; (120% moisture contents), unirrigated (90~100%) and more un irrigated candition (80~90% moisture content), and levels of the various irrigation periods; usual, initial, intermediate and final periods, being treated. The results obtained in this experiment are as follows: 1. As for the physical and chemical and soil properfies, and other characteristics, there are no differences among the treatments enough to be effective for the growth of rice plants. 2. Culm length was measured after harvest as shown in table 2. 3. Difference of the amount of irrigation water did not change the culm length and ear length, however it also indicated more apparent increase in final treatment plots thatn that of usual. 3. No difference in the number of ears and number of ears pers per hill was founded treatments both in the difference of water supply and in the various irrigation periods. 4. There is no difference in the maturing rate and 1000 grains weight. 5. The number of panicles and grains and more increased in 80~100% moisture contents soil than those of 120%. and it shows in un irrigated plots, more irrigated plots and control plots in turn. Other wise according to the period\ulcorner of irrigation the trend is appeared in turn initial, usual, final and intermediate treatments.6. Yield as shown in table 7. 8 was more increased in unirrigated plots(90~IOO% moisture content) than the control plots (120% moisture content) by up to 8.2% and also 3. 2% in more unirrigated plots than that of control by periods is shown: usual plots final, initial, inter mediate treatment plots in turn. 7. The above resutts lead to the conclusion that no remarkable, differences in yields and soil properties are made by the unirrigation. However, it is apparent that this treatment has .some advantages in the points that one could spare the amount of water supply for irrigation with more increase in yield. In addition, a higher temperature and a brisk oxygen supply would be possible throug h this treatments. Accordingly, these treatment would be a more reasonable and economical cultivation method of rice for the better harvest.

• Korean Journal of Environment and Ecology
• /
• v.12 no.3
• /
• pp.279-289
• /
• 1998

To monitor vegetation structure of evergreen broad-leaved forest, twenty plots were set up at Wando Arboretum in 1996. Twenty plots were divided into ten experimental plots and control plots. A few evergreen broad-leaved species were planted after selective cutting at ten experimental plots. Dominant species of twenty plots were Quercus acuta, Q. acuta and Carpinus tschonoskii, Pinus densiflora, etc.. Vegetation structure of the experimental plots showed seral stage of succession from P. densiflora community or deciduous broad-leaved forest to Q. acuta community. Dominant species of the experimental plots were changed to Q. acuta or P. densiflora after selective cutting. And a number of species and individuals, coverages etc. were increased at shrub and ground cover layer after treatment.

• Journal of the Semiconductor & Display Technology
• /
• v.12 no.4
• /
• pp.9-13
• /
• 2013

Lapping is a very complicated and random process resulting from the variation of abrasive grains in its sizes and shapes and from the numerous factors having an effect on the process quality. This paper presents a study of a $2^4$ full factorial experimental design and analysis to optimize surface quality in lapping operation. The optimization of the factors to obtain minimum surface roughness was carried out by incorporating effect plots, main effect plots, interaction plots, analysis of variance(ANOVA), surface plots, and contour plots. The statistical design experiments, designed to reduce the total number of experiments required, indicated that, within the selected conditions, all the parameters influenced at a significance level of 5%. In addition, some of the possible interactions between these parameters also influenced the lapping process, especially those that were of third order. A regression model was suggested and fitted the experimental data very well.

• The Korean Journal of Applied Statistics
• /
• v.22 no.6
• /
• pp.1153-1165
• /
• 2009

There are many traditional statistical tests for randomness. We can consider recurrence plots as an exploratory graphical tool for evaluating randomness.

• The Korean Journal of Applied Statistics
• /
• v.23 no.2
• /
• pp.285-293
• /
• 2010

The traditional methods for evaluating response surface designs are alphabetic optimality criteria. These single-number criteria such as D-, A-, G- and V-optimality do not completely reflect the prediction variance characteristics of the design in question. Alternatives to single-numbers summaries include graphical displays of the prediction variance across the design regions. We can suggest the animated quantile plots as the animation of the quantile plots and use these animated quantile plots for comparing and evaluating response surface designs.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.61 no.2
• /
• pp.119-123
• /
• 2016

This study was conducted to evaluate the effect of plant number per hill (PNH) on growth and yield of foxtail millet in drained paddy fields. Crop growth, development, and yield in the field were examined for 2 years to assess the efficiency of proposed cropping system. The greatest culm length of 138 and 148 cm in the first and the second year, respectively, at the harvest stage was observed in plots with one plant per hill. The greatest culm diameter of 7.79 and 7.67 mm in the first and second year, respectively, was measured in plots with one plant per hill. The greatest tiller number of foxtail millet in plots with one plant per hill was 2.9 and 2.7 in the first and the second year, respectively. However, there was no significant difference between plots with four and five plant per hill. Among the measured yield components, the spike length and seed number per spike were one plant per hill in both years. The highest grain yield of foxtail millet ($324kg{\cdot}10a^{-1}$ and $333kg{\cdot}10a^{-1}$ in the first and second year, respectively) was obtained from plots with two plants por hill, followed by plots one, three, four, and five plants per hill.

• Korean Journal of Organic Agriculture
• /
• v.16 no.4
• /
• pp.455-469
• /
• 2008

A research was conducted to investigate the effect of treatment of woody charred materials such as wood vinegar, charcoal, and mixture of wood vinegar and charcoal on the growth and components of tomato and chinese cabbage. The effect of treatment of woody charred materials on the growth and components of tomato the research findings are as follows. The total number of soil microorganisms increased in the groups treated with woody charred materials compared with the control. The fruit number, fruit length, fruit diameter, fruit weight, hardness and sugar contents of tomato did not show significant difference in all plots treated with woody charred materials, but the plot treated with wood vinegar + charcoal showed relatively higher values in general. Vitamin C contents were shown higher in the plots treated with woody charred materials than the control, and among the treatment plots. The effect of treatment of woody charred materials on the growth and components of chinese cabbage the research findings are as follows. The soil chemical components did not change before and after the treatment of woody charred materials. The total number of soil microorganisms increased in the treatment plots compared with the control, The leaf length, leaf width, inner leaf number, plant weight, and head weight of Chinese cabbage treated with woody charred materials were in general larger than the control. Among the treatment plots, the plot treated with wood vinegar + charcoal showed slightly higher values. The contents of minerals in chinese cabbage such as Ca, Fe, K, Mg and Mn were higher in the treatment plots than the control.

• The Korean Journal of Ecology
• /
• v.18 no.4
• /
• pp.471-481
• /
• 1995

The weed population dynamics as affected by contrasting conventional tillege (CT) and no-tillage (NT) practices with a minimum herbicide application was studied in Athens, Georgia, U.S.A. Common chickweed (Stellaria media) was the most common spring weed while johnsongrass (Sorghum halepense), sicklepod (Cassia obtusifolia), and pigweed (Amaranthus retroflexus) accounted for 89∼97％ of net production during summers of 1983 and 1984. Total weed production in summer of 1984 was 2∼5 times greater than that of 1983. Weed production was greater in NT plots than in CT plots in summer of 1983, but reverse was the case in summer of 1984. In spring, net production in NT plots was greater than that in CT plots, especially, in 1985. Species diversity was consistently higher in NT plots, but in the wet summer of 1984 the pattern was different, with higher diversity in CT plots. Weed species diversity was higher in the spring rye crop than in the summer grain sorghum crop. The larger but less diverse weed populations in summer of 1984 indicated that these populations experienced competitive exclusion. Under the favorable summer moisture conditions the three dominant species grew so vigorously and quickly as to exclude many less common species that were able to survive under the drier conditions in 1983. The three dominant species not only excluded other weeds in 1984 but also greatly reduced crop production. The perennial johnsongrass was equally successful, or even more so, in CT plots as in NT plots. Plowing did not kill johnsongrass rhizomes but tended to break them up, thus increasing the number of individual plants that appear after the plowing. It means that johnsongrass was not controlled by the plowing. In summer of 1983, a moderate amount of weedy growth was maintained with a minimum amount of gerbicide application in NT and CT plots. It is possible that a small mixed weed population would be beneficial by providing cover for predatory and parasitic arthropods, and by reducing soil temperature and moisture losses.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.25 no.2
• /
• pp.23-30
• /
• 1980

Experiments were conducted to know N, P, and K top dressing effects on yield and other agronomic characters of rice plants grown in 5-year differently fertilized soils. Four levels of nitrogen, 0, 1.2, 2.4, and 3.6kg/10a, were applied 32 days before heading in 5-year non-fertilized and PK applied plots. Four levels of P_2 $O_{5}$ and K_2 O of 0, 4, 8 and 12kg/l0a were applied 40 days before heading in 5-year NK and NP applied plots, respectively. 1. Heading was delayed by seven days in 5-year non-fertilized and PK applied plots compared to NK, NP, or NPK applied plots where nitrogen was applied as basal. However, in 5-year non-fertilized and PK applied plots heading was delayed from 1 to 4 days as amounts of nitrogen top dressing increased. Phosphorus and potassium did not affect heading date of rice plants. 2. In 5-year non-fertilized plot grain yield increased as amounts of nitrogen top dressing increased up to 2.4kg/l0a due to both increased number of panicles per hill and spikelets per panicle. However, in 5-year PK applied plot amounts of nitrogen top dressing did not affect grain yield; the number of panicle per hill increased, but the percentage of ripened grains and grain weight tended to decrease as nitrogen levels increase. 3. The number of panicle/maximum tillers ratio in percentage increased markedly as amounts of nitrogen top dressing increased in 5-year non-fertilized and PK applied plots with maximum value of 130% on the basis of maximum tillers at vegetative stage. 4. Top dressing of phosphorus and potassium did not affect yield and other agronomic characters in NK and NP applied plots.