• Journal of the Korean Geotechnical Society
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• v.22 no.5
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• pp.5-12
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• 2006

In this study a series of tests (bench scale test) are carried out for increasing the strength of clayey soil by EK-Injection method. In addition, the effects of strength increase in the treated sample are measured by operating the vane shear test device during 25 days at 5 days intervals in order to estimate the effect of ground improvement caused by diffusion. Also, the effects of strength increase in the treated sample are measured by operating the vane shear test device to estimate the effect by treatment durations (5, 10, 15, 20, 25). The test results show that the strength increase was developed approximately 2 to 7 times in comparison to initial shear strength, and outstanding strenfth increase was created as much as 7 times while injecting the sodium silicate and phosphoric acid in anolyte and catholyte. In addition, the measured shear strength with the influence of diffusion and reduction of water-content had a tendency to converge in constant value in proportion to elapsed time. As a result of this study, strength increment developed by the influence of EK-Injection and diffusion rather than the reduction of water-content was 1000% high on average. In case of changes of treatment duration, strength increment developed by the influence of treatment durations rather than the reduction of water-content was 3 to 4 times high on average.

• Journal of Digital Convergence
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• v.20 no.3
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• pp.231-240
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• 2022

This study empirically analyzed the effect of complex commercial facilities on the price of nearby apartments in a Hedonic price model. The spatial range of this study was the walking area of H Department Store located in Pangyo among the second new towns suburb of Seoul, and the time range was 2020. The dependent variable was the real transaction price of the apartment, and independent variable were the characteristics of the housing, the characteristics of the complex, and the characteristics of the region. As a result of the analysis, the area of exclusive use space, the transaction floor, and the highway accessibility had a positive effect on the price of the apartment, and the elapsed year had a negative effect on the price of the apartment. However, the size of the apartment had little effect on apartment prices, and the distance from the complex commercial facilities was shown to be related to apartment prices, indicating that apartment prices declined as it moved away from the complex commercial facilities. Therefore, this is much more influential than the influence of distance from subway stations on apartment price. This confirms that the effect factors of apartment prices and the size of their influence appear differently in the new town area and the existing metropolitan area.

• Journal of Marine Life Science
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• v.1 no.1
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• pp.50-55
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• 2016

Glucose was continuously increased as time was elapsed under the temperature at 6℃ and 4℃. NH₃ was significantly increased at 4℃. AST was increased as temperature and salinity were decreased which indicated that it was affected by temperature, salinity and interaction of temperature×salinity. ALT was significantly increased as temperature was decreased. Free amino acid contents, excluding aspartic acid, threonine, serine and glycine were increased as temperature was decreased. This decreasing tendency was also observed when salinity was decreased. Taurine, aspartic acid, glutamic acid and arginine were significantly increased as salinity was decreased, while glycine, alanine, methionine, tyrosine, and histidine were decreased as salinity was decreased. The result of this study suggested that transport condition to minimize the stress is considered in the range of 30~34 psu, 8~10℃.

• The Journal of the Acoustical Society of Korea
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• v.28 no.3
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• pp.198-207
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• 2009

Distribution of cavitation bubbles relative to change of the sound speed and attenuation in the water was estimated using acoustic signal from 20 to 300 kHz in two cases that cavitation bubbles exist and do not exist. To study generation and extinction property of cavitation bubble, bubble distribution was estimated in three cases: change of rotation speed (3000-4000 rpm), surface area of blade ($32-98\;mm^2$) and elapsed time (30-120 sec). As a result, the radii of the generated bubbles ranged from 10 to $60{\mu}m$, and bubble radius of $10-20{\mu}m$ and $20-30{\mu}m$ was accounted for 45 and 25% of the total number of cavitation bubbles, respectively. And generation bubble population correlated closely with the rotating speed of the blades but did not correlate with the surface area of blade. It was observed that 80% of total bubble population disappeared within 2 minutes. Finally, acoustic data of bubble distribution was compared with optical data.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.5
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• pp.161-168
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• 2008

The freeze-thaw deterioration and chloride attack, which are the typical degradation factors for durability of marine concrete, are significantly affected by pore structures in terms of penetration and diffusion. These pore structures of concrete are closely related to the types and amount of AE agent, used to guarantee the resistance of freeze-thaw deterioration, and the elapsed time before concrete pouring. This paper evaluates the durability of concrete based on the results of tests on cylinder specimens and core specimens from mock-up members with different air content of 4~6% and 8~10%, respectively. According to the test results, the air content of hardened concrete is 2.5~5.2% at 7 days and 2.4~5.1% at 28 days. These air contents are about half of the initial values just after the concrete mixing. Judging from the amount of scale after the freeze-thaw test completed, air content of 8~10% is slightly more beneficial against the deterioration of concrete than air content of 4~6%. Meanwhile, the core specimens from mock-up members exhibit somewhat unfavorable freeze-thaw deterioration and chloride migration characteristic compared with the cylinder specimens tested in the laboratory under the same mixing condition, as to show 106% in freeze-thaw test and 160% in chloride diffusion coefficient test, respectively.

• The Journal of Korean Academy of Prosthodontics
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• v.47 no.2
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• pp.108-118
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• 2009

Statement of problem: Volume stability, microstructure reproducibility and fluidity along with compatibility with dental stone must be in consideration in order to use tissue conditioner as a material for functional impression. There are few studies concerning the influence of time factor in oral condition on surface roughness of the stone and optimal retention period in the oral cavity considering such changes in surface roughness. Purpose: The purpose of this study was to find out the influence of various kinds of tissue conditioner, its powder/liquid ratio and immersion time on surface roughness of the stone. Material and methods: Materials used in this study were the three kinds of tissue conditioners(Coe-Comfort, Visco-Gel, Soft-Liner) and were grouped into three: group R-mixed with standard powder/liquid ratio that was recommended by the manufacturers, group M-mixed with 20% more powder, group L-mixed with 20% less powder. Specimens were made with the size of 20 mm diameter and 2 mm width. Each tissue conditioner specimens were subdivided into 5 groups according to the immersion time(0 hour, 1 day, 3 days, 5 days, 7 days), completely immersed into artificial saliva and were stored under $37^{\circ}C$. Specimens of which the given immersion time elapsed were taken out and were poured with improved stone, making the stone specimens. Surface roughness of the stone specimens was measured by a profilometer. Results: Within the limitation of this study, the following results were drawn. 1. Major influencing factor on surface roughness of the stone model made from tissue conditioner was the retention period(contribution ratio($\rho$)=62.86%, P<.05) of the tissue conditioner in oral cavity to make functional impression. 2. In case of Coe-Comfort, higher mean surface roughness value of the stone model with statistical significance was observed compared to that of Soft-Liner and Visco-Gel as immersion time changes(P<.05). 3. In case of group L(less), higher mean surface roughness value of the stone model with statistical significance was observed compared to that of R(recommended) and M(more) group as immersion time changes(P<.05). Conclusion: We may conclude that as the retention period of time in oral cavity influences surface roughness of the stone model the most and as the kind of tissue conditioner and its P/L ratio may influence also, clinician should well understand the optimal retention period in oral cavity and choose the right tissue conditioner for the functional impression, thus making the functional impression with tissue conditioner usefully.

• 한국유가공학회:학술대회논문집
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• 2002.11a
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• pp.23-40
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• 2002

This study was conducted to investigate the quality changes of the UHT(ultra-high temperature), LTLT(law temperature long time) and HTST(high temperature short time) treated milk samples by storage conditions for 6 months from August 2000 to February 2001. The UHT treated milk samples collected from 3 plants(A, B and C) were stored at l0$^{\circ}$C and room temperature(dark and light exposure) for 6 months, and the LTLT and HTST treated milk samples(D and E) were also stored for 30 days. The UHT pasteurized milk of A, B and C plant was treated at 130$^{\circ}$C for 2-3s, 133$^{\circ}$C for 2-3s and 135$^{\circ}$C for 4s, respectively. The UHT sterilized milk of A and B plant was treated at 140$^{\circ}$C for 2-3s and 145$^{\circ}$C for 3-4s, respectively. The LTLT milk of D plant was treated at 63$^{\circ}$C for 30 mins, and the HTST milk of E plant was treated at 72$^{\circ}$C for 15s. All of the raw milk samples collected from storage tank in 5 milk plants were showed less than 4.0 X 10$^5$cfu/ml in standard plate count, and normal level in acidity, specific gravity, and component of milk. Preservatives, antibiotics, sulfonamides and available chloride were not detected in both raw and heat treated milk samples obtained from 5 plants. One(10%) of 10 UHT pasteurized milk samples obtained from B plant and 2 (20%) of 10 from C were not detected in bacterial count after storage at 37$^{\circ}$C for 14 days, but all of the 10 milk samples from A were detected. No coliforms were detected in all samples tested. No bacteria were also detected in carton, polyethylene and tetra packs collected from the milk plants. A total of 300 UHT pasteurized milk samples collected from 3 plants were stored at room(3$^{\circ}$C ${\sim}$ 30$^{\circ}$C) for 3 and 6 months, 11.3%(34/300) were kept normal in sensory test, and 10.7%(32/300)were negative in bacterial count. The UHT pasteurized milk from A deteriorated faster than the UHT pasteurized milk from B and C. The bacterial counts in the UHT pasteurized milk samples stored at 10$^{\circ}$C were kept less than standard limit(2 ${\times}$ 10$^4$ cfu/ml) of bacteria for 5 days, and bacterial counts in some milk samples were a slightly increased more than the standard limit as time elapsed for 6 months. When the milk samples were stored at room(3$^{\circ}$C ${\sim}$ 30$^{\circ}$C), the bacterial counts in most of the milk samples from A plant were more than the standard limit after 3 days of storage, but in the 20%${\sim}$30%(4${\sim}$6/20) of the milk samples from B and C were less than the standard limit after 6 months of storage. The bacterial counts in the LTLT and HTST pasteurized milk samples were about 4.0 ${\times}$ 10$^3$ and 1.5 ${\times}$ 101CFU/ml at the production day, respectively. The bacterial counts in the samples were rapidly increased to more than 10$^7$ CFU/ml at room temperature(12$^{\circ}$C ${\sim}$ 30$^{\circ}$C) for 3 days, but were kept less than 2 ${\times}$ 10$^3$ CFU/ml at refrigerator(l0$^{\circ}$C) for 7 days of storage. The sensory quality and acidity of pasteurized milk were gradually changed in proportion to bacterial counts during storage at room temperature and 10$^{\circ}$C for 30 days or 6 months. The standard limit of bacteria in whole market milk was more sensitive than those of sensory and chemical test as standards to determine the unaccepted milk. No significant correlation was found in keeping quality of the milk samples between dark and light exposure at room for 30 days or 6 months. The compositions of fat, solids not fat, protein and lactose in milk samples were not significantly changed according to the storage conditions and time for 30 days or 6 months. The UHT sterilized milk samples(A plant ; 20 samples, B plant ; 110 samples) collected from 2 plants were not changed sensory, chemical and microbiological quality by storage conditions for 6 months, but only one sample from B was detected the bacteria after 60 days of storage. The shelflife of UHT pasteurized milk in this study was a little longer than that reported by previous surveys. Although the shelflife of UHT pasteurized milk made a significant difference among three milk plants, the results indicated that some UHT pasteurized milk in polyethylene coated carton pack could be stored at room temperature for 6 months. The LTLT and HTST pasteurized milk should be sanitarily handled, kept and transported under refrigerated condition(below 7$^{\circ}$C) in order to supply wholesome milk to consumers.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.35 no.2
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• pp.161-169
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• 1999

This paper describes the swimming and escaping behavior of amber fish, Seriola aureovittata released in the first bag net of the setnet and observed with telemetry techniques. The setnet used in experiment is composed of a leader, a fish court with a flying net and two bag nets having ramp net. The behavior of the fish attached an ultrasonic depth pinger of 50 KHz is observed using a prototype LBL fish tracking system. The 3-D underwater position ofthe fish is calculated by hyperbolic method with three channels of receiver and the depth of pinger. The results obtained are as follows: 1. The fish released on the sea surface was escaped down to 15 m depth and rised up to near the sea surface during 5 minutes after release. The average swimming speed of the fish during this time was 0.87 m/sec. 2. The swimming speed of the fish is decreased slowly in relation to the time elapsed and the fish showed some escaping behavior forward to the fish court staying 1 to 7 m depth layer near the ramp net. The average speed of the fish during this time was 0.52 m/sec. 3. During 25 minutes after beginning of hauling net, the fish showed a faster swimming speed than before hauling and an escaping behavior repeatedly from the first ramp net to the second one in horizontal. In vertical, the fish moved up and down between the sea surface and 20 m depth. After this time, the fish showed the escaping behavior forward to fish court after come back to the first ramp net in spite of the hauling was continued. It is found that the fish was escaped from the first ramp net to the fish court while the hauling was carried out. The average speed of the fish after beginning of hauling was 0.72 m/sec which increased 38.5 ％ than right before the hauling and showed 0.44 to 0.82 m/see of speed till escaping the first bag net. The average swimming speed during observation was 0.67 m/sec (2.2 times of body length).

• Korean Journal of Poultry Science
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• v.20 no.3
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• pp.133-140
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• 1993

A study was conducted to investigate the concentrations of Ca, P and ash in metatarsal bone of broiler chicks exposed to UV light in different Interval. Day-old Hubbard broiler chicks (199＝10 control＋3 irradiation interval $\times$ 9 elapsed time $\times$ 7 replicate) were fed vitamin D3 deficient diet for 3 wk in a windowless subdued-light room and exposed to 297 nm UVB light by 0.068 mJ/$\textrm{cm}^2$ three times In 0, 12 or 24 h interval. The metatarsal bones were taken at 0, 6, 12, 18, 24, 48, 96, 144 or 240 h after last irradiation, separated from adhering tissue, ether extracted, dried and ashed. The Ca concentration was measured by atomic absorption spectrophotometry and P by ammonium metavanadate colorimetry. When the birds were continuously exposed to UVB light for 30 min without interval, the Ca content in metatarsus increased gradually according to the time after irradiation and reached the highest value 16.75% at 240 h after exposure. The P content also increased gradually until 144 h, where it was 9.75%. The ash content in metatarsus increased continuously until 240 h, the final time in this research, where 42.75% was shown. As 10 min three times irradiation in 12 h interval was applied to the chicks, the metatarsal Ca presented a small peak(13.31%) at 12 h after irradiation and a large peak(16.91%) at 144 h. P content showed a small peak(7.18%) at 12 h and a large level(8.34%) at 240 h. Ash content increased continuously until 240 h, where it was 46.53%. The small peaks in Ca and P concentration were thought to be derived from preirradiation at 12 and 24 h before final irradiation for 10 min. When 24 h interval system was treated, the peak value of Ca content(24.18%) occurred earlier(96 h) than those in 0 and 12 h interval systems. P content also showed the maximum value at 96 h(7.29%). Ash content presented an increasing trend until 240 h, where 45.75% was appeared. In respecting the method of UVB irradiation, the peak value of Ca content in metatarsus appeared earlier in 24 h interval system than in other systems. Meanwhile the ash contents in metatarsus of birds exposed to UVB light in 12 and 24 h interval procedures were higher than those in 0 h interval one. Therefore, it was concluded that a daily 10 min irradiation of UVB light would be desirable for increasing the Ca and ash content in metatarsus of brolier chicks.

• The Korean Journal of Ecology
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• v.17 no.3
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• pp.299-310
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• 1994

Intraspecific clonal interactions have important influences on a population structure of the cellular slime mold (CSM). This study was to investigate whether or not evolutionary change in a population could be induced by clonal competition, and to elucidate how various clones in a population evolve in a homogeneous environment of laboratory culture. The characteristic clones of Polysphondylium pallidum which had different resource consumption rates (RCR) and mating types I and II were selected for study. Investigation was conducted for 4 experimental time interval $(T_0-T_4)$; one experimental time interval took almost 10-14 days from inoculation to havest of fruiting bodies. Two sets of 50 clones were cultured from 50 clones at To, and RCR variations of the population were compared between $(T_0\;and\;T_4)$ for each set of clones. Each clone of the CSM had a diverse resource consumption rate, or growth rate, in a homogeneous and limited Cerophyl agar plate despite the passage of 48-56 generations from the beginning of the experiment. Diverse clones with different growth rate could coexist in one site of the homogeneous agar plate as well as heterogeneous soil microenvironment. When there was high clonal diversity of RCR, a clone in a population had high chances to encounter other clones with resultant increased clonal competition. In one set, 26 of 37 clones of mating type I were changed to mating type Il for the 4 experimental time intervals, which indicated that the rate of competitive exclusion among clones during total experiment from $(T_0\;to\;T_4)$ was 0.703. In another set, 31 of 37 clones of mating type I were changed to mating type II , having the rate of competitive exclusion 0.838. The frequency of each of mat~ng types changed by 0.93-1.29% in each successive generation. The competitive exclusion among clones occurred by 1.26-1.75% when approximately $2.6{\times}10^8$ bacterial cells were provided as food and thereafter one generation of myxamoebae of CSM elapsed at room temperature. This finding implicated that in the vegetative state of P, pallidurn there was 1.26-1.75% probabil~ty of evolutionary change per generation changing from one clone to another clone.