• Magazine of the Korean Society of Agricultural Engineers
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• v.14 no.1
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• pp.2535-2548
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• 1972

Instead of fertilizing the lands they moved to find other fertile lands and lived a feudal life agriculture and various machincs played a main role in the land reclamation. The best method of land clearing, the time and capacity in the operation and the effect of growing crops should systematically analized prior to the time of 3rd Five-year Economic Development(1972-1976) in order to cultivate 210,000ha of wasteland or the modernization of our country. The present study was investigated to find out a new working-system of mechanical land clearing and development of fertile soil. The results are as follows: 1) The first stage of productive power increases when weeds were mixed soil in the land clearing work in order to supply organic materials and to make soil swollen instead of burning or just removing. 2) The equipments such as bulldozers, harrows, power tillers and so on should be prepared in order to do a systematic work in the land clearing. 3) The work of pulling-up roots is dependent upon the forms of roots spreading under the ground. The work of the pulling-up of the straight roots was most difficult. But before the roots are pulling-up we do not know the forms of roots. 4) The cutting of soil from upside to under side land clearing method (II) Spent 6 hr 7 min 43 sec per 1 Danbo in doing land clearing and control method spent 4 hr 52 min 30 sec per 1 Danbo in doing land cearing. No significant difference could be found between II treatment type and I treatment type. 5) The volume of soil carried by bulldozer $270.38m^3$ per 1 Danbo in I type and in II type, $368.58m^3$ per 1 Danbo or about 36% increased in II type then in I type. But that is not a significant difference when considering the whole productive power of soil. 6) The land clearing of terrace by bulldozers cannot escape making the embankment slope of about $45^{\circ}$, and 25.3% should be decreased in the area. It is recommended to make use of the embankment slope by planting grass for cows. 7) The time of retary tilling increased 2.3 times or 1 hr 42 min 22 sec per 1 Danbo compared to the timesrequired in the harrowing. Because it mixed the Organic matter on ground and the harrowing of subsoil. 8) The havest of pasture growing on the land reclamation in natural slope is as follows. (a) The none fertilizers with reclaimed block of productivity decresed 1/10 than that of the farmland. Therefore the none fer tilizing in the cultivated pasture is unprofitable. (b) The havest of the manured IV treatment block was the best not only in the kinds of fertilizers but also in the kinds of pasture grass.

• Magazine of the Korean Society of Agricultural Engineers
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• v.17 no.1
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• pp.3627-3641
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• 1975

The Government is trying to increase total food grain yield to meet national self sufficiency by means of increasing unit yield as well as extending crop land, and this year he set the target of 321,000 hectare of forest to clear for cropping. This study was carried to investigate the most efficient method of clearing hillock by bulldozer, and successful method to develope yielding potential of newly cleared land in short term. Since the conventional land clearing method is just earth leveling and root removing neglecting top soil treatment, the growth of crop was poor and farmer tends not to care the land. The top-soil-furrowing method is applied through out this study, that is advantageous especially for the land having shallow top soil and low fertility like Korean forest. In this study, various operating method were tried to find out most efficient method separately in connection with the land slope less than 25 percent and over, and several fertilizing methods to develop yielding potential. The results are as follows; 1) For the natural land slope utilization method, applicable to the land having less than 25 percent slope, reverse operating was more efficient than using forward gear of bulldozer. The operating time was 3 hour 32 minutes and 36 seconds using forward gear was 2 hour 32 minutes and 30 seconds for reverse gear operation per 1,000 square meter. 2) Bulldozer having angle blade adjustment needed 7hr 15min. for constructing of terrace per 10a compaire with the one having angle & tilt adjustment needed 6hr 4min for same operations. Specially there is significant difference for operation time of first period (earth cutting) such as bulldozer having angle blade adjustment needed 3hr 56min compaired with the one having angle & tilt adjustment 3hr 59min. In construction of terrace, the bull-dozer having tilting and angle blade adjustment was most suitable and performed efficiently. 3) For the fertilizer application treatment, the grass (Ladino clover) yield in first year was almost same as ordinary field's in the plot applied(N.P.K+lime+manure) while none fertilizer plot showed one tenth of it, and (N.P.K.+lime) applied plot yielded on third. 4) The effect of different land clearing method to yield showed significant difference between each treatment especially in the first year, and the conventional method was the lowest. In the second year, still conventional terracing plot yielded only half of ordinary field while the other plots showed as same as ordinary field's. 5) The downward top soil treatment plot showed most rapid improvement in soil structure during one year physio chemically, it showed increase in pH rate and organic composition, and the soil changed gradually from loam to sand-loam and the moisture content increased against the pF rate, and it gives good condition to grow hay due to the increase of field water capacity with higher available water content. 6) Since the soil of tested area was granite, the rate of soil errosion was increased about 2 to 5 percent influencing in soil structure more sand reducing clay content, and an optimum contour farming method should be prepared as a counter measure of errosion.

• Journal of Embryo Transfer
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• v.16 no.1
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• pp.35-40
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• 2001

Artificial insemination (AI) with frozen or cooled semen is widely used in commercial fields of cattle and pig. Little is known about characteristics of canine sperm after freezing or cooling. For both practical and commercial goal, the canine semen treated with cooling and freezing should be carried out to exam the fundamentals, including sperm motility, survivability and fertilizing capacity. The aim of this study, thus, was to identify the effects of extended exposure to 4$0^{\circ}C$ on canine semen by motility, survivability, acrosomal changes following different duration. Fifteen ejaculates collected by digital manipulation twice per week from 3 dogs (Shih-Tzu) were divided to 16 aliquots after adding Tris-egg yolk (TE) buffer formulated by our laboratory, and cooled from 37 to 4$^{\circ}C$, by ramp rate of 0.6$^{\circ}C$/min. Each sample was evaluated by their motility, survivability and the acrosomal status at 0h (control), 2h, 12h and 1 d~10 d, respectively. The motility of spermatozoa was graded to 6 levels using the modified method of Seager. The survivability of sperm was assessed using an epifluorescence microscope after Fert/Light (Mole-cular Probes Inc.) staining. To estimate the proportion of the spermatozoa of intact acrosome, 200 spermatozoa were assessed in randomly selected fields, using epifluorescence microscope after FITC/PSA (Sigma) staining. At 2 h after cooling, the motility of most spermatozoa were assessed to be grade 0 and 1. At 12 h, high number of sperm were in grade 0 to 1, however, it was significantly (P<0.05) lower than that of 2 h. From 1 d to 4 d, ~50% of sperm was assessed to grade 0 to 1. On day 7, a little sperm were in grade 0 to 1. No sperm showed motility on day 10. Sperm motility was rapidly reduced by the percent of 10% of grade 0 to 1. From 2 h to 6 h, the number of live sperm was 90% and the sperm chilled for 10 days lived>50%. Acrosomal intact of spermatozoa exposed to 4$^{\circ}C$ for 2 h was 51%, supposed the sperm of control was 100%. Our results suggest that 1) this is easy to transfer and preservation for short periods 2) AI can be used by semen chilled for 6-Day.

• Korean Journal of Soil Science and Fertilizer
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• v.41 no.1
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• pp.18-25
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• 2008

Pseudomonas sp. PRGB06, a bacterial strain isolated from diamondback moth (Plutella xylostella) gut, was examined for its plant growth promotion and biofertilizing traits. The bacteria growth was observed under various conditions of carbon sources, temperature, pH and salt concentrations. In addition, the mechanisms of antagonism and phosphate solubilization were investigated. The bacterial strain PRGB06, grew well using most of the tested carbon sources. The best growth was observed at $30^{\circ}C$ and pH 7. The inhibition of the pathogenic fungi was likely due to the volatile antifungal metabolite and ammonia gas produced by the bacteria. A significant positive relationship was found between the phosphate solubilization and acid production. When inoculated with PRGB06 in vitro and in gnotobiotic condition, red pepper and maize showed increase in root length, seedling vigor and dry bio-mass.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.15
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• pp.69-75
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• 1974

This experiment was conducted to investigate the influence of different amount of nitrogen and deficiency of soil moisture on yield components of soybean. Soybean were seeded on 1/2000a wagner pot. Deficiency of soil moisture was treated at each growth atage of soybean. 1.In case of deficiencyt of soil moisture at the flowering time in the plot of non-nitrogen(NO D3), the growth duration of soybean was shortened about three to four days. 2. The leaf area was greatly affected by the influence of both treatments till 49days after germinating. 3.The increase of stem height, stem doameter,number of branches and lengeh of the branches came to an end about 70 days after seeding. These growing condition of tje soybean were lowest the plot of No D$_1$,in which the frowth of the soybeans were poor at the early stage. 4.The number of pods was not increased by the increase of fertilizing nitrogenous fertilizer. The number of pods was much decreased by the influence of soil mousture deiciency, and under this condition, the proportion of main stem pods and two or three grain pods was high. 5.The 3rd and 4h nodes and the 10th to 12th nodes from bottom had more pods than the other nodes had, but of the plants had grown well, they had more pods on the 3rd and 4th nodes, but if the plants had grown poorly, they had more pods on the 10th to 12th nodes. 6.The content of protein in the soybean was low at the plit of N。D$_4$which had not heavy weight of 100 grains, and the content of oil in the soybean was low in the plot in which each plant had a small number of grains.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.37 no.6
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• pp.499-505
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• 1992

This experiment was carried out to find out the optimum application method of slow-release fertilizer under different soil textures, clay loam(Deogpyeong series), sandy loam (Gangseo series) in the southern region(Milyang, Kyeongnam) of Korea. The fertilizers used were Chosun slow-release fertilizer(silicate latex coated fertilizer: N-P$_2$O$_{5}$-K$_2$O=18-12-13) and Meister 15 (thermoplastic resin coated fertilizer : N-P$_2$O$_{5}$-K$_2$O=14-14-14). The two whole basal application methods such as side band placement at transplanting time of rice plant(cv.Donghaebyeo) and incorporation with soil as basal were tested. The released amount of ammonium nitrogen from the soils for 4 days submerged was 95ppm in sandy loam and 60ppm in clay loam. The greenish degree of rice leaf was higher at the whole plow layer placement method than the others. The nitrogen efficiencies of the fertilizers were Meister 15 > convention > Chosun in order and between the application methods were similiar. The growth status was better at the whole plow layer placement application method of Meister 15 regardless of soils and seedling ages. The ripening ratio was increased at slow-release fertilizer application, and between application methods, whole plow layer placement was lower because of lodging damage. The yield in clay loam soil showed a significant difference between the ferilizers, but there were slight differences between the application methods and fertilizers in sandy loam soil. As a result, the slow-release fertilizer, Meister 15, applied at the whole layer showed a good rice growth and seemed a plausible fertilizing method.

• Journal of Aquaculture
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• v.19 no.3
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• pp.166-172
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• 2006

Induced androgenesis, a form of artificial parthenogenesis is an important tool for the generation and use of genetically isogenic or clonal fish strain. An optimized protocol for the genetic inactivation of mud loach (Misgurnus mizolepis) oocytes (i.e. production of androgenetic haploid) was developed using UV-irradiation. Various dose levels of UV significantly affected the fertilizing capacity of the eggs, hatchability of embryos and incidence of haploidy. Based on the extensive examinations of treatment conditions on embryo viability and haploid incidence, the optimum dose level of UV irradiation was turned out to be $10,800ergs/mm^2$ with 56.9% of hatching success and 94.6% of haploidy. The overall yield of putative androgen under optimized treatment condition was more than 50% out of total eggs inseminated. The success of androgenetic reproduction of haploid genome was verified by flow cytometry and PCR amplification of transgene that is exclusive to either one of parental sexes. However, a small portion $(8\sim11%)$ of presumed androgenetic haploid larvae was proven to contain residual DNA fragment(s) from maternal parent.

• Applied Microscopy
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• v.34 no.1
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• pp.43-50
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• 2004

In this study, we examined effects of environmental endocrine disruptor bisphenol A on the reproduction of Xiphophorus maculatus. We exposed the males of X. maculatus to the bisphenol A adjusted to the various concentrations such as 100 ppb, 200 ppb, 400 ppb and 800 ppb for 3 months for the experimental groups and then inbreeded with normal females that was not any treated. We counted the number of second generation for confirmation of fertilizing ability of first generation. Also, we observed the ratios of female and male, the abnormality and mortality, and spermatogenesis of the second generation was exposed to bisphenol A for 6 months. As the result, the number of fry in the second generation was $11.50{\pm}2.22$ in 100 ppb, $6.40{\pm}2.76$ in 200 ppb, $5.70{\pm}1.34$ in 400 ppb and $3.70{\pm}2.11$ in 800 ppb at the experimental groups while it was $19.00{\pm}3.02$ at the control group which was not treated with bisphenol A. This result showed that the experimental groups exhibited a decreasing tendency according to the increase of bisphenol A concentration comparing with the control group. The ratio of female and male of the second generation had no relations with the concentration of bisphenol A, and the ratios of abnormality and mortality were 0%. The spermatogenesis of experimental groups was normal in 800 ppb as well as 100 ppb, 200 ppb, 400 ppb after even 6 months.

• Clinical and Experimental Reproductive Medicine
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• v.25 no.2
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• pp.171-177
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• 1998

The combination of testicular sperm extraction (TESE) with ICSI can achieve normal fertilization and pregnancy rate and is effective method in obstructive and non-obstructive azoospermic patients. But, when pregnancy was not occurred, repeated testicular biopsies are not evitable. Therefore, in this study, we observed the survival rate of testicular spemratozoa and spermatozoa extracted from the seminiferous tubules after cryopreserved-thawed used for next IVF cycle with ICSI. In a total of 23 cases, obstructive azoospermia was 17 cases and non-obstructive azoospermia was 6 cases. In obstructive azoospermia, after thawing, motile spermatozua was observed in 13 cases (76.5%). The fertilization rate with 2PN was 67.6% and 5 pregnancies (29.4%) were achieved. In non-obstructive azoospermia, motile spermatozoa was observed in 2 case (33.3%) after thawing. The fertilization rates with 2PN was 53.7% and 3 pregnancies (50.0%) were achieved. A comparison of the results of motile spermatozoa after thawed testicular spermatozoa and spermatozoa extracted from the thawed seminiferous tubule section were 3 cases (60.0%) and 12 cases (66.6%), respectively. The fertilization and pregnancy rates of thawed testicular spermatozoa and spermatozoa extracted from the thawed seminiferous tubule section were 69.4% and 20.0%, 62.5% and 38.8%, respectively. Conclusively, thawed testicular spermatozoa and spermatozoa extracted from the thawed seminiferous tubule section can achieve normal fertilization and pregnancy and cryopreservation of testicular spermatozoa and seminiferous tubule may avoid repetition of testicular biopsies in azoospermic patients in whom the only source of spermatozoa is the testis.

• The Korean Journal of Zoology
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• v.39 no.4
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• pp.437-446
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• 1996

The courtship and fighting behaviors and the sexual dimorphism of the salamander Hynohius leechil were studied. The parameters, snout vent length, body length (from snout to tail tip), and proportion of snout vent length to body size were larger in the female than the male. Five physical parameter in males were significantly correlated with one another, body length, snout vent length, head width, tail vent length, and tall depth, while all, except tail depth, were significantly correlated in females. Sexual behavior of H. leechIl involved external fertilization and consisted of three stages, identifying the female, aifrading the female, and insemination. The identification stage consisted of a positive advance by the male toward the female and display of snout contact. The male attracted the female with chin rubbing, tail undulation, smelling, and digging displays. The insemination process consisted of four phases, amplex, separating egg sacs from the female's cloacal, fertilizing eggs, and post fertilization. liighting behaviors were quite simple. The attacking male would generally bite the opposite male's upper chin or hind limbs and then shakes his head two or three times. The bitten male, which in most cases was of a dissimilar body size, quicidy escaped from the attacking male. After fighting, winning male usually displayed rapid tail undulation.