• Korean Journal of Agricultural Science
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• v.10 no.2
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• pp.292-309
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• 1983

This study is intended to find out the degree of compaction in field compaction, with soil type, the thickness of soil layer and the number of roller passing through the field density test and the field C. B. R. test by comparing vibration and non-vibration compactions. The results in this study are summarized as follows. 1. When the number of roller passing is few, it shows that the efficiency of the compaction by vibratory compaction is greater than that by non-vibratory compaction, the difference of the compaction ratio between vibratory and non-vibratory compaction is decreased according as the number of roller passing is more frequent. 2. Mechanizing on a large scale it is possible for a large equipment to be able to reach the point of A-1 compact ion method with three to five times of roller passing. To provide for mechanizing on a larger scale it is advisable to fix the standard by the D-2 compaction method. 3. As dry-density increases, the C. B. R. value increases, but the increasing ratio of C. B. R. value showed greater in vibrating compacting. 4. According as the number of roller passing increases, the increasing tendency of the C. B. R. Value is slow and the difference of the C. B. R. value between vibration and non-vibration compaction is large, the C. B. R. value showed greater about 20% in vibration compaction than in non-vibration compaction. 5. In C-5 soil type, with increasing the thickness of compaction, the degree of compaction is decreased. When the thickness of compaction is increased from 20cm to 30cm, the degree of compaction is decreased slowly, while the thickness of the compaction is increased from 30cm to 40cm the degree of compaction is decreased remarkably. Therefore it is advisable to compact the ground under the thickness of 30cm.

• Korean Journal of Agricultural Science
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• v.14 no.2
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• pp.358-372
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• 1987

This study was performed to obtain data which can be applied to use of water-proof mortars. The data was based on the properties of water-proof mortars depending upon various mixing ratios to compare those of cement mortar. The water-proof agents used were retard and accelerate type which are being used as mortar structures. The water-proof agents, mixing ratios of cement to fine aggregate were 1:1, 1:2, 1:3 and 1:4. The results obtained were summarised as follows; 1. The results of flow test, water-cement ratio was increased with the increasing of mixing ratio. 2. The permeability were increased in poorer mixing ratio and higher water pressure. 3. The bulk density was decreased with the increasing of mixing ratio, and compressive and tensile strength were increased with increasing of the bulk density. 4. At 1:1 mixing ratio, the highest strengths were showed and strengths were decreased with the increasing of mixing ratio. 5. The absorption rates were increased in- poorer mixing ratio 6. The correlation between W/C, permeability, bulk density, compressive strength and absorption rate were highly significant as a straight line, respectively.

• Korean Journal of Agricultural Science
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• v.11 no.2
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• pp.233-243
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• 1984

The present study was carried out to determine the changes of the sex hormone levels in serum throughout the estrous cycle and the gestation period on the Landrace gilts. The blood samples were taken from the vein of six gilts. LH, FSH, prolactin, progesterone, $estradiol-17{\beta}$ and cortisol in serum were analyzed by the radioimmunoassay methods. The results obtained on this study were summarized as follows; 1. The age at puberal estrus was 179.5 days, the weight at puberal estrus was 88.2kg, the length of estrous cycle was 21.3days, the gestation length was 114days and the litter size was 9.5 head in the Landrace gilts. 2. During the estrous cycle, the serum LH and prolactin concentrations were below 1.56mIU/ml and 2.4ng/ml, respectively, under the limit of detection of the assay. The FSH concentrations ranged from 1.50 to 2.20mIU/ml for day 6~15 after the estrus and they were below 1.25mIU/ml from day 3 to day + 3, with day 0 being the first day of the estrus. 3. Progesterone concentrations were 1.90ng/ml at day 0 of the estrus and increased about 13.1ng/ml at day 3 of the estrus, and reached peak levels at day 9. $Estradiol-17{\beta}$ concentrations were below 27.2pg/ml throughout the luteal phase, and reached about 27.2pg/ml at day 0 and day 18. Cortisol concentrations reached peak levels at dey 0 and ranged from 24.65 to 28.57ng/ml throughout the luteal phase. 4. During the gestation period, the concentrations of LH, FSH and prolactin ranged of 3.10~4.37mIU/ml, 1.30~1.80mIU/ml and 2.60~6.70ng/ml, respectively. 5. Progesterone concentrations declined from 38.90~16.85ng/ml throughout the pregnancy to 1.90ng/ml at the time of parturition. $Estradiol-17{\beta}$ concentrations increased from 27.20pg/ml at 15 days after the pregnancy to 620.17pg/ml at the time of parturition. Cortisol concentrations reached peak levels at the time of parturition and ranged from 13.58 to 22.31ng/ml throughout the pregnancy.

• Korean Journal of Agricultural Science
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• v.11 no.2
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• pp.223-232
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• 1984

The influences of some factors involved in removing glucose from egg white by the glucose oxidase system be fore drying were investigated. And the properties between foams prepared from raw and enzyme-treat ed egg white was compared. The results obtained we re summarized as follows; 1. The dianisidine method was found to be suitable for the measurement of egg white glucose in the range up to 100ug/ml. 2. The optimal pH of glucose oxidase activity on glucose was found to be a bout 5.0, and thats activity was most stable in the pH range of about 4.0~5.0 when that enzyme was treat ed for 30 minute at $50^{\circ}C$. 3. The optimal temperature for glucose oxidase reaction on glucose was found to be about $20^{\circ}C$, and that enzyme activity was s table up to $50^{\circ}C$. 4. The removing rate of glucose from egg white with glucose oxidase was influenced by the enzyme concentration, pH and oxygen addition, and the react ion time of the desugarization was about 10 hour sunder the conditions of 0.5% hydrogen peroxide, pH 7.0 and $26^{\circ}C$. 5. All of the each egg white treated with glucose oxidase, glucose oxidase+pancreatin, glucose oxidase+trypsin showed highly foaming ability than that of natural egg white(control), but thats foam stability, on the contrary, was reversed.

• Korean Journal of Agricultural Science
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• v.14 no.2
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• pp.272-285
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• 1987

In order to obtain the data for the effective separation and purification of lysozyme from egg white, optimal conditions for the homogenization of egg white and lysozyme activities of some fresh hen eggs were examined. The recovery and purity of lysozyme isolated by the direct crystallization method, the adsorption with Bentonite and the batch method with Duolite were also investigated. The results obtained were summarized as follows; 1. On the homogenization of egg white, optimal stirring time and stirring rate for the measurement of the lysozyme activities were found to be 10 min. and 2,000 rpm respectively. 2. On the activities of lysozyme in the fresh hen eggs, the activities of W. Leghorn was greater than that of R. Island or Ogol fowl, and the activities of the thick white was a little greater than that of the thin white. 3. The residual lysozyme activities of the hen eggs stored at $4^{\circ}C$ was greater than that of the ones stored at $25^{\circ}C$ or $-20^{\circ}C$ over the storage periods. 4. Hen egg lysozyme recrystallized three times by the method of direct crystallization showed the recovery of 64.3% and the increase of 29 fold in specific activities. 5. By the adsorption method with bentonite, lysozyme in the egg white was adsorbed to 95.7%, and the elution rate of the ones adsorbed was 89.1%, and the increase in specific activities was 13 fold. 6. In the experiment exploying duolite as an adsorbent, Jysozyme in the egg white was obtained with the bound rate of 97%, the recovery rate of 84.8%, and was purified by 30fold.

• Korean Journal of Agricultural Science
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• v.14 no.2
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• pp.263-271
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• 1987

The cyclical trend and seasonal variations of chestnut prices have been analyzed to find out the chestnut price fluctuation in Korea during 1966-1985. The optimum prices, production, and plantation area for the next twenty five years (1986-2010) have been forcasted by the derived equation models. The results of study can be summarized as follows: 1. The chestnut prices were increased by 14.67 percent per annum during 1966-1972, an d decreased by 9.24 percent during 1973-1985, due to the excessive production of chestnut. 2. The chestnut prices showed the lowest price during the harvesting season, especially in October (89.1), and highest in July (109.1). Seasonal fluctuation of chestnut prices were 0.0837 (C.V value) during 1966-1975, and 0.0706 during 1976-1985. Such a seasonal fluctuation of chestnut prices tends to be even with the passage of time. 3. The equation model of predicted chestnut prices was derived as follows : PR=117788.088 - 7.60 TC/Pop + 6.585 GNP/Pop The chestnut prices will be the lowest in 1988, but increased rapidly thereafter. 4. The equation model of optimum chestnut production was derived as follows : $${\ell}n\;PD/Pop=-8.5147-0.8267{\ell}n\;PR+3.3063{\ell}n\;GNP/Pop$$ To maintain optimum chestnut prices according to this model, chestnut production should be 133,000 ton for 1988, and 1,899,000 ton for 2010. 5. Optimum chestnut plantation area will be 4,000 ha in 1988, and thereafter total plantation area will be up to 57,400 ha in 2010.

• Korean Journal of Agricultural Science
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• v.14 no.2
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• pp.318-328
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• 1987

The results of experiment to review the optimum pasteurization condition for the raw milk produced in Korea by using UHT procedure of $100-145^{\circ}C$, the changes in chemical composition, microbiological aspects and the keeping quality of the heat treated milk are summarized as follows: 1. In UHT milk sterilized at $100-145^{\circ}C$, the pH value decreased from 6.55 to 6.33 but protein, fat, lactose and ash did not show significance changes while casein nitrogen and non-protein nitrogen increased but non-casein nitrogen and filterable nitrogen decreased. 2. Calcium content decreased gradually from 119.8 mg/100 g of raw milk to 75.75 mg/100 g at $145^{\circ}C$ as the heat treatment increased and vitamin C decreased rapidly from 1.37 mg/100 ml to 0.82 mg/ 100 ml while artificial digestibility increased from 14.07% of raw milk to 26.0% as the heat treatment increased. 3. As the heat treatment increased, microorganism counts decreased to $0.5{\times}10^2/ml$ and were not found above $135^{\circ}C$ - coliforms and psychrotrophic bacteria from $100^{\circ}C$ thermoduric bacteria, thermophiles, mould and yeast from $125-130^{\circ}C$. Heat treatment above $135^{\circ}C$ showed 100% sterilization effect. 4. The result of preservation test for heat treated milk did not show any significant changes in titratable acidity and general composition at $4^{\circ}C$, $25^{\circ}C$ and $37^{\circ}C$ up to 15 days. Viable bacteria counts, coliforms and psychrotrophic bacteria were not found but loss of vitamin and increase in viable bacteria counts appeared after 20 days.

• Korean Journal of Agricultural Science
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• v.15 no.2
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• pp.153-163
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• 1988

This experiment was carried out to obtain the thermophilic fungus producing amylase and to investigate properties of the amylase. The selected strain, L-11 was obtained from soil in the vicinity of a hot spring and identified as Mocor sp.. And then the conditions for enzyme production in wheat bran cultures and properties of the crude enzyme were investigated. Furthermore, the enzyme was purified and the characteristics of purified enzyme were studied. The results obtained were as follows: 1. On the wheat bran medium added 80-100% water, amylase was effectively produced by the selected strain, L-11 for 48 hrs incubation at $50^{\circ}C$. 2. When the crude enzyme solution of the strain L-11 was passed through DEAE-Sephadex A-50 column chromatography, two peaks having amylase activity were obtained, and one peak was that of the main enzyme (enzyme of B peak). 3. The purified enzyme (enzyme of B peak) was recognized as single protein band on polyacrylamide disc gel electrophoresis. 4. In the hydrolysis reaction of soluble starch by the enzyme of main amylase, oligosaccharides produced at early stage were maltose and maltotriose mainly and procedure of the reaction maltose amount of maltose and glucose was increased. 5. The strain L-11 was recognized as a special strain producing ${\alpha}-amylase$ mainly and scarcely glucoamylase. 6. The optimum pH, optimum temperature, pH stability, and temperature stability of ${\alpha}-amylase$ were pH 4.0, $60-65^{\circ}C$, pH 4.0-9.0, and below$70^{\circ}C$.

• Korean Journal of Agricultural Science
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• v.10 no.2
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• pp.334-344
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• 1983

This study was conducted to investigate the variables affecting the performance of hammer mills by the theoretical and dimensional analysis, and evaluate the power requirements of hammer mills for farm use in Korea. From the theoretical analysis, 16 variables affecting the performance of hammer mills were defined. In order to develop the mathematical relationships among the variables, the dimensional analysis was made for power requirements and $12{\pi}$ parameters were obtained. For the evaluation of the power requirements of hammer mills, approximate rates of grinding for 1HP, 3HP, 5HP, 6HP, 8HP, and 10HP were analyzed. Then, the fineness of grinding recommendation and average feeding rate of grain for livestock which is native cattle, dairy cattle, beef cattle, swine, broilers, and layers, were estimated. Finally number of livestock feeding shelled corn and barley were estimated from the above for one hour's hammer mill operation having the various power requirements. From this study it is known that 5HP is considered as an enough power for feed grinding of any kinds of livestock of Korean farm, as far as the grinding capacity is concerned.

• Korean Journal of Agricultural Science
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• v.11 no.2
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• pp.207-217
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• 1984

Seasonal growth performances or root collar diameter and seedling height of Quercus acutissima. Q. mongolica and Q. variabilis were measured at regular intervals of 10 or 15 days after the treatments of some combinations of soil water regime ${\times}$ fertilization. The treatments of soil water regime and fertilization Influenced on the growth performances of seedlings differently with one another in course of time lapse. The growth performances revealed highly significant differences between soil water regimes, between fertilizations and between their interactions after unlike time lapses by species. The effects of soil water regime were exhibited in retard compared with those of fertilization, and to be different outstandingly in the treatments of N or N+P+K fertilization. The limit of soil water potential influencing critically on the growth performances might be estimated to be in -3~-6 bar in all the species. The growth responses were significantly different between N or N+P+K treatment and P or K treatment or control in all the species, and the treatment effects represented more great differences in moist soil water regime than in dry soil water regime. The interactions of soil water regime ${\times}$ fertilization were revealed s lowly with time lapse in all the treatments. The statistical differences of growth responses of root collar diameter according to the treatments were observed in earlier stage compared with those of seedling height. By comparison of the growth responses of the species studied, Q. variabilis and Q. mongolica seemed to be more resistant to moisture stress than Q. acutissima.