• Journal of Biosystems Engineering
• /
• v.5 no.1
• /
• pp.51-57
• /
• 1980

It is desirable to increase the diameter of rice bundle harvested by Japanese reaper binder recently introduced into Korean farmers , since it is too small for stalking in the field for preliminary drying prior to threshing operation which is dominant procedure in rice harvesting . Accordingly, this study was conducted to analyze the effect of the size of rice-bundle on the performance of binder and self-feeding thresher. The results are summarized as follows : 1. The diameter of rice-bundle could be increased from $\phi$80-98 to $\phi$105.0-125.4 while the number of rice bundles per 10 a were reduced to 1200 from 1600. The time required for harvesting 10 a of rice was 81 minutes in small size bundles and 84 minutes in large size bundles and no statistical difference was obtained. 2 .The grain loss due to discharge and cutting were slightly increased with large size bundle compared to the small size but no statistical difference was obtained. The precision of operation and drying rate was not significantly different between small and large size bundles. 3. The unthreshed losses were the same between large and small sizes of rice bundles when self-feeding thresher was used. When 8 PS engine was used , continuous operation was possible for small size bundles , but 1.5seconds of time interval was necessary for large size buldles. 4. The consumption of binding twine was reduced to 603 from 820 meters with the larger bundles , and the labour requirement for stalking rice bundles in the field was also reduced to 1.83 form 2.50 man-hour per 10 a Therefore, harvesting cost can be reduced up to 26.5 percent by increasing the bundle size.

• Asian-Australasian Journal of Animal Sciences
• /
• v.11 no.1
• /
• pp.65-70
• /
• 1998

To understand the caused for poor response to superovulation in water buffalo compared to crossbred cows, follicular events, before start of superovulation, during superovulation and after superovulation were compared. Follicular development was monitored a day before start of superovulation, daily upto superestrus and on the day of flushing. A real time B mode diagnostic instrument equipped with a linear array, 5 MHz transducer was used in five crossbred cows and five Murrah buffaloes. Crossbred cows yielded significantly (p < 0.01) higher number of corpora lutea than buffaloes (21 vs 10). The mean number of small size (2 to 5 mm); medium size (6 to 9 mm) and large size $({\geq}10mm)$ follicles, a day before start of superovulation were almost similar or even slightly higher in buffalo. Though initial shift in the mean number of follicles was higher in buffalo than cow, yet, from Day 2 to Day 3 of the treatment, the average increase in medium (3.2 vs 1.2) and large size (5.0 vs 2.0) follicles was higher in cows than buffaloes. The mean number of medium and large size follicles was 9.8 and 14.4 in cows and 6.4 and 7.6 in buffaloes. On the day of flushing, the number of large size follicle was more in buffaloes than cows, indicating the ovulation problem in this species. The major conclusion from this investigation was that, a day before start of superovulatory treatment, the number of small and medium size follicles was slightly higher in buffaloes, even then superovulatory response was better in cows, due to shift, recruitment and passage of follicles from smaller size to larger size from Day 2 of treatment. Ovulation problem in buffaloes was also responsible for lower superovulatory responses as revealed by the presence of higher number of large size follicles on the day of flushing.

• Journal of the Korean Society of Safety
• /
• v.34 no.3
• /
• pp.28-35
• /
• 2019

Dry water is a core-shell structured powder which comprises a very fine water core covered with hydrophobic silica particles. Recently, the dry water has attracted attention as a new type of fire extinguishing agents. However, characteristics of the dry water as a fire extinguishing agent have not been revealed until now. To our best knowledge, this is the first work to uncover effects of particle size of the dry water on the fire extinguishing performance. Pristine dry water, which has heterogeneous particle size distribution, was carefully separated by sieving method into three fractions which were a small size (ca. $110{\mu}m$) fraction, a medium size (ca. $220{\mu}m$) fraction and a large size (ca. $400{\mu}m$) fraction. Microscopic observations confirmed the effective separation of dry water's particle size. In extinguishing tests of wood cribs fire, the medium size dry water showed most excellent fire extinguishing performance, as compared to other dry waters having small (ca. $110{\mu}m$) and large (ca. $400{\mu}m$) particle size. The good performance of the medium size (ca. $220{\mu}m$) dry water may be attributed to the balance between cooling effect of the water core and smothering effect of the silica particles. It is also revealed that small size dry water has poor flowability than large size dry water.

• Korean Journal of Materials Research
• /
• v.16 no.10
• /
• pp.633-638
• /
• 2006

Silica powders with spherical shape and narrow size distribution were prepared by large-scale ultrasonic spray pyrolysis applying the droplet classification apparatus. On the other hand, silica powders prepared by large-scale ultrasonic spray pyrolysis without droplet classification apparatus had broad size distribution. Droplet classification apparatus used in this paper applied the principles of cyclone and dispersion plate with small holes. The droplets formed from the ultrasonic spray generator applying the droplet classification apparatus had narrow size distribution. The droplets with fine and large sizes were eliminated by droplet classification apparatus. The optimum flow rate of the carrier gas and diameter of the hole of the dispersion plate were studied to reduce the size distribution of the silica powders prepared by large-scale ultrasonic spray pyrolysis. The size distribution of the silica powders prepared by large-scale ultrasonic spray pyrolysis at the optimum preparation conditions was 0.76.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.7 no.2
• /
• pp.29-36
• /
• 1987

In most of the structural members with initial cracks, the strength tends to decrease as the member size increases. This phenomenon is known as size effect. Among the structural materials of glass, metal or concrete, etc., concrete represents the size effect even without initial crack. According to the previous size effect law, the concrete member of very large size can resist little stress. Actually, however, even the large size member can resist some stress if there is no initial notch. This means that the fracture mechanism of very small or very large size member follows strength criterion, but the medium size member follows non-linear fracture mechanics (NLFM). In this study, the empirical models which are derived based on nonlinear fracture mechanics are proposed according to the regression analysis with the existing test data of large size specimens for uni-axial compression test, splitting tensile test and shear test of reinforced concrete beams.

• Journal of the Korean Ceramic Society
• /
• v.30 no.5
• /
• pp.365-372
• /
• 1993

Variation of dielectric constant in PMN-Pyrochlore diphasic mixtures were investigated with grain size of pyrochlore phase. Size of pyrochlore phase was controlled by the numbers of calcining and sedimentation method during powder processing. When grain size of pyrochlore phase is large in the sintered specimen, dielectric constant slowly decreased with increase of amount of pyrochlore phase. On the contary, grain size of pyrochlore phase is small, dielectric constant drastically decreased. It was thought that small sized pyrochlore grains more easily surrounded high dielectric phase (perovskite PMN) than large ones with addition of pyrochlore phase.

• Journal of the Korean Institute of Telematics and Electronics B
• /
• v.33B no.7
• /
• pp.107-115
• /
• 1996

The average distortio of the vector quantizer is calcualted using a probability function F of the input source for a given codebook. But, since the input source is unknown in geneal, using the sample vectors that is realized from a random vector having probability function F, a time-average opeation is employed so as to obtain an approximation of the average distortion. In this case the size of the smple set should be large so that the sample vectors represent true F reliably. The theoretical inspection about the approximation, however, is not perfomed rigorously. Thus one might use the time-average distortion without any verification of the approximation. In this paper, the convergence characteristics of the time-average distortions are theoretically investigated when the size of sample vectors or the size of codebook gets large. It has been revealed that if codebook size is large enough, then small sample set is enough to obtain the average distortion by approximatio of the calculated tiem-averaged distortion. Experimental results on synthetic data, which are supporting the analysis, are also provided and discussed.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2004.05a
• /
• pp.575-580
• /
• 2004

The latest equipment automatic Intelligence of digital base done large size equipment appear in succession. That run by voltage electric current(mA, mV, ${\mu}A,\;{\mu}V$) that outline is microscopic of action of accuracy large size equipment of this digital base is bulk. Have received influence that is great in river electric field by installment that use computer. Most of domestic working voltage from service entrance extra-high voltage and working voltage of commercial frequency 60Hz working voltage 220V that use our country outside 1 country in interior of 22.900V for semiconductor use computer use digital installment of appliance as well as various smalls of digital base, middle, large size that safety is these fine voltage electric current that is not enough direct admonition hundred vast damage give can. Also, already act in surge circle and impulse transient phenomena such as several thousands, myriads, strong bit error more than billions time to digital fine electronic circuit by mistake use of using electric facility system of system electric power.

• Animal Systematics, Evolution and Diversity
• /
• v.14 no.1
• /
• pp.51-57
• /
• 1998

Thirty one morphometric characters of striped field mice(Apodemus agrarius) from eight localities in Korea were analyzed by multivariate methods in order to confirm taxonomic status of specimens from Wando island. Two subgroups were recognized: a small-size form from six localities (Mt. Taebaek, Mt. Weolak, Cheongju, Mt. Chiri, Kunsan, and Jin isoland) and a large-size form from Wando island and Cheju island. It is confirmed that the small-size form from six localities is A. a. coreae, as described by Thomas(1908), and that the large-size form from Cheju island is A. a. chejuensis, as named by Johnson and Jones (1955). Furthermore, it is confirmed that large-size specimens from Wando island is and Cheju island. It is confirmed that the small-size form from six localities is A. a coreae, as described by Thomas(1908), and that the large-size form from Cheju island is A. a. chejuensis, as named by Johnson and Jones(1955). Furthermore, it is confirmed that large-size specimens from Wando island is subspecies A. a. chejuensis, as suggested by koh (1989). In future, analyses with specimens from islands in southern coasts are necessary to clarify the taxonomic status of Apodemus agrarius in Korea.

• Journal of Ecology and Environment
• /
• v.41 no.8
• /
• pp.223-234
• /
• 2017

Background: Spatial structure of plants in a population reflects complex interactions of ecological and evolutionary processes. For dioecious plants, differences in reproduction cost between sexes and sizes might affect their spatial distribution. Abiotic heterogeneity may also affect adaptation activities, and result in a unique spatial structure of the population. Thus, we examined sex- and size-related spatial distributions of old-growth forest of dioecious tree Torreya nucifera in extremely heterogeneous Gotjawal terrain of Jeju Island, South Korea. Methods: We generated a database of location, sex, and size (DBH) of T. nucifera trees for each quadrat ($160{\times}300m$) in each of the three sites previously defined (quadrat A, B, C in Site I, II, and III, respectively). T. nucifera trees were categorized into eight groups based on sex (males vs. females), size (small vs. large trees), and sex by size (small vs. large males, and small vs. large females) for spatial point pattern analysis. Univariate and bivariate spatial analyses were conducted. Results: Univariate spatial analysis showed that spatial patterns of T. nucifera trees differed among the three quadrats. In quadrat A, individual trees showed random distribution at all scales regardless of sex and size groups. When assessing univariate patterns for sex by size groups in quadrat B, small males and small females were distributed randomly at all scales whereas large males and large females were clumped. All groups in quadrat C were clustered at short distances but the pattern changed as distance was increased. Bivariate spatial analyses testing the association between sex and size groups showed that spatial segregation occurred only in quadrat C. Males and females were spatially independent at all scales. However, after controlling for size, males and females were spatially separated. Conclusions: Diverse spatial patterns of T. nucifera trees across the three sites within the Torreya Forest imply that adaptive explanations are not sufficient for understanding spatial structure in this old-growth forest. If so, the role of Gotjawal terrain in terms of creating extremely diverse microhabitats and subsequently stochastic processes of survival and mortality of trees, both of which ultimately determine spatial patterns, needs to be further examined.