• Journal of Korean Institute of Industrial Engineers
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• v.7 no.1
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• pp.5-11
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• 1981

In the case of numerical implementation, the exact solution method for the M/M/s system where customers demand multiple server use [2] reveals limitations, if a system has large number of servers or types of customers. This is due to the huge matrices involved in the course of the calculations. This paper offers an approximation scheme for such cases. Capitalizing the characteristics of the service rate curve of the system, this method approximates the service rate as a piecewise linear function. With the service rates obtained from the linear function for each number of customers n (n=0. 1. 2,$\cdots$), ${\mu}(n)$, steady-state probabilities and measures of performance are found treating this system as an ordinary M/M/s system. This scheme performs well when the traffic intensity of a system is below about 0.8. Some numerical examples are presented.

• Phonetics and Speech Sciences
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• v.10 no.4
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• pp.1-10
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• 2018

This study introduces an automated Praat script allowing optimal formant analysis for children's vowels. Using Burg's algorithm in Praat, formants can be extracted by setting the maximum formant value and the number of formants. The optimal formant setting was determined by identifying the two conditions, F1 and F2, with minimum standard deviations. When applying the optimal formant setting determined by the script, the results of normality tests were not significant among all vowels except /e/ for the maximum formant value, and among the vowels /a/, /e/, /i/, /o/, /u/ and /ʌ/ for the number of formants. This indicates that when analyzing the formants of children's vowel sounds, the unilateral application of a parameter setting (the maximum formant value and the number of formants) to all vowels is problematic. The performance of the optimal formant setting script was evaluated along with 3 different algorithm in order to determine whether it properly extracts formants for children's vowels. To this end, Korean monophghongs of 6-year-old children were collected and the Praat scripts were applied to the data. Resultant Formant plots and statistical analysis showed that optimum_script and qtone_script, which links to the perceptual unit, performed very well in formant extraction compared to the remaining 2 scripts.

• Journal of the Korean Mathematical Society
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• v.6 no.1
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• pp.47-50
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• 1969

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.1 no.4
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• pp.305-312
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• 1989

Laminal natural convection heat transfer in the annulus between isothermal horizontal non-circular cylinders is studied by solving the Navier-Stokes and energy equation using an elliptic numerical procedure. Results are obtained to determine the effects of the diameter ratio($D_o/D_i$) and Rayleigh number on heat transfer. The diameter ratio is varied from 1.5 to 13.0 at Pr=0.7, H/L=1.5 and $10^3{\leqslant}Ra_L{\leqslant}4{\times}10^4$. It is found that the diameter ratio causes a more significant on the local heat transfer coefficient of lower semi-circular cylinder and plate than upper semi-circular cylinder. The mean Nusselt number increases as the diameter ratio and Rayleigh number increase, and is higher than that of the circular annulus with a same wetted perimeter.

• Journal of Aquaculture
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• v.9 no.4
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• pp.345-351
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• 1996

Mass production of resting egg of the rotifer, Brachionus plicatilis was carried out in 1 $m^3$ tank for L-type rotifer and in 1 $m^3$ and 4 $m^3$ tank for S-type rotifer. L-type rotifer was fed on concentrated Chlorella + baker's yeast and only baker's yeast for 15 days. S-type rotifer was fed on concentrated Chlorella in 1 $m^3$ tank for 7 days and frozen Chlorella + baker's yeast in 4 $m^3$ for $6\~8$ days. Total number of resting egg and number of resting egg from $10^8$ rotifers and 1 g dry weight diet for L-type rotifer fed on Chlorella + baker's yeast were $54.5{\times}10^6$ eggs, $30.5{\times}10^6$ eggs and $100{\times}10^3$ eggs, respectively. These were higher than those of rotifer fed on baker's yeast only. Total number of resting egg and number of resting egg from $10^8$ rotifers and 1 g dry weight diet for S-type rotifer fed on concentrated Chlorella in 1 $m^3$ tank were $50\~104{\times}10^6$ eggs, $47\~82{\times}10^6$ eggs and $136\~260{\times}10^3$ eggs, respectively. In 4 $m^3$ tank with frozen Chlorella + baker's yeast, these were $149\~567{\times}10^6$ eggs, $36\~123{\times}10^6$ eggs and $131\~338{\times}10^3$ eggs, respectively. This result suggests that S-type rotifer are better than L-type rotifer for the mass production of resting egg of the Korean rotifer.

• Korean Journal of Animal Reproduction
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• v.27 no.4
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• pp.339-347
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• 2003

The purpose of this study was to investigate the development of bovine nuclear transfer (NT) embryos cultured in serum-free conditions. Bovine NT embryos cultured in various culture conditions were compared blastocyst development, total cell number and apoptosis using TUNEL assay. In experiment 1, blastocyst rates of NT embryos were significantly higher (P<0.01) in FBS (22.0％) and BSA (26.6％) groups than in PVA (6.3％) group. Total cell number was significantly higher in FBS (78.4$\pm$19.4) and BSA (90.9$\pm$29.1) groups than in PVA group (46.0$\pm$0.0). Apoptotic cell number was significantly fewer in FBS (3.1$\pm$1.4) and BSA (1.7$\pm$1.4) groups than in PVA group (7.0$\pm$20.0) However, all of results were not different between the FBS and BSA group. In experiment 2, blastocyst rates of NT embryos were significantly higher (P<0.05) in fatty acid free-BSA (FAF-BSA) group (26.8％) than in fraction V-BSA group (11.2％). Total cell number were somewhat higher in FAF-BSA group (89.8$\pm$30.7) than in fraction V-BSA group (88.1$\pm$19.3). Apoptotic cell number were somewhat fewer in FAF-BSA (1.7$\pm$1.5) group than in fraction V-BSA group (4.2$\pm$2.9). These findings suggest that serum free condition were effective for the in vitro development of bovine NT embryos. Therefore, we concluded that fatty acid free-BSA has beneficial effect in development bovine NT embryos and can be use as a serum substitute.

• Journal of Preventive Medicine and Public Health
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• v.12 no.1
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• pp.38-42
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• 1979

The objectives of this study were to identify the determinants of the 1. Home visiting activities by FHWs 2. Utilization of village Family Health Workers(FHWs) 3. Attitudes towards FHWs 4. Knowledge about FHW's activities] among housewives in the Kang Wha Community Health Project area This study was analysed by using path analysis Exogenous variables were 1. Distance between the housewives' houses and that of their local FHW 2. Duration of work of each FHW as FHW in her village 3. Number of preschool children in the households Endogenous variables were 1. Home visiting frequency to each household by FHW 2. Knowledge about FHW's activities 3. Attitude towards FHWs 4. Utilization of FHW] by the housewives The results were as follows: The shorter the distance between client's and FHW's house, the higher the number of preschool children in the household, and the longer the duration of work of FHW as FHW, the higher is the number of her household visits in a given time span. The more frequently the FHW visits a household and the higher the knowledge about FHW's activities in the household, the more positive is the attitude of the housewives to the FHW and the more frequently she visits and utilizes the FHW on her own initiative.

• The Research Journal of the Costume Culture
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• v.3 no.1
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• pp.65-82
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• 1995

The purpose of this research is to grasp the factors behind a mother's behavior in purchasing baby's clothes and to investigate how her purchasing behavior is affected by the baby's age, sex, rank, her age, her educational background, her place of residence, her occupation, the number of children's and family's monthly income. for this purpose, questionnaires were used and personal interviews with 481 mothers who bring up from newborns to two-year-old babies in Seoul ere conducted. Through this research, some facts have been found as follows. 1. Mother's behavior in purchasing baby's clothes are affected by baby's variables such as the baby's age, sex and rank, particularly it is much affected by baby's rank. 2. Mother's behavior in purchasing baby's cloths are affected by mother's variables such as the mother's age, educational background, place of residence, occupation, the number of children's and family's monthly income. Particularly it is much affected by mother's educational background and family's monthly income.

• Journal of Power System Engineering
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• v.10 no.3
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• pp.17-22
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• 2006

Surface modifications like rib-roughening and displaced insert devices like the twisted tape are commonly used in applications such as compact heat exchangers and cooling systems. In this paper, regionally averaged heat transfer distributions in square channels with twisted tape inserts and with twisted tape inserts plus interrupted ribs are respectively investigated. The square ribs are arranged to follow the trace of the twisted tape and along the flow direction defined as axial interrupted ribs. Each wall of the square channel is composed of isolated aluminum sections. Regionally averaged Nusselt number and channel averaged Nusselt number in turbulent air flows are presented for Reynold numbers from 8,900 to 29,000. We have obtained the following conclusions from the experimental study: 1) The local Nusselt number in the two-sided heated case is higher than that in the four-sided heated condition. 2) In the 4 heating wall channel with twisted tape inserts, Nusselt number based on bottom wall temperature is enhanced by 1.2 - 1.6 times if adding the axial interrupted ribs on the bottom wall only. 3) The twisted tape with interrupted ribs under the two-sided heating condition produces the highest heat transfer coefficient.

• The Journal of the Korean Society for Microbiology
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• v.18 no.1
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• pp.11-21
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• 1983

Various investigations have been carried out to elucidate the causative relationship between specific oral bacterial species and dental caries since it was first demonstrated that selected streptococoal species produced dental caries in germfree rats when fed a high-sucrose diet. Now, S. mutans is considered to play an important role in the development of dental caries in animals and humans, and only a limited number of species of bacteria other than S. mutans are occasionally found to be cariogenic in experimental animals. In this regard, association of the number of S. mutans in approximal plaque with caries experience (DMFT) was studied from 137 Korean school children($10{\sim}11$ year old). Biotypes of the collected strains of S. mutans were determined, and their relationship with caries status was also examined. The following results were emerged from the study. 1. S. mutans was detected in the plaques of all children. 2. Statistically significant positive correlation(r=0.445, p<0.001) was found between the caries experience(DMFT) and the number of S. mutans in approximal plaques. 3. The number of S. mutans were significantly higher(p<0.001) in plaques removed from carious surface than from sound surface. 4. The most frequent biotype was biotype I(78.8%), followed by IV(33.1%) and V(09.5%). Biotype II was isolated in the plaque of two children(1.7%) only. 5. There was no apparent relation of specific biotypes to carious status.